Resveratrol: From the folks who brought you Nilotinib

 

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Recently the results of a small clinical study looking at Resveratrol in Alzheimer’s disease were published. Resveratrol has long been touted as a miracle ingredient in red wine, and has shown potential in animal models of Parkinson’s disease, but it has never been clinically tested.

Is it time for a clinical trial?

In today’s post we will review the new clinical results and discuss what they could mean for Parkinson’s disease.


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From chemical to wine – Resveratrol. Source: Youtube

In 2006, there was a research article published in the prestigious journal Nature about a chemical called resveratrol that improved the health and survival of mice on a high-calorie diet (Click here for the press release).

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Title: Resveratrol improves health and survival of mice on a high-calorie diet.
Authors: Baur JA, Pearson KJ, Price NL, Jamieson HA, Lerin C, Kalra A, Prabhu VV, Allard JS, Lopez-Lluch G, Lewis K, Pistell PJ, Poosala S, Becker KG, Boss O, Gwinn D, Wang M, Ramaswamy S, Fishbein KW, Spencer RG, Lakatta EG, Le Couteur D, Shaw RJ, Navas P, Puigserver P, Ingram DK, de Cabo R, Sinclair DA.
Journal: Nature. 2006 Nov 16;444(7117):337-42.
PMID: 17086191          (This article is OPEN ACCESS if you would like to read it)

In this study, the investigators placed middle-aged (one-year-old) mice on either a standard diet or a high-calorie diet (with 60% of calories coming from fat). The mice were maintained on this diet for the remainder of their lives. Some of the high-calorie diet mice were also placed on resveratrol (20mg/kg per day).

After 6 months of this treatment, the researchers found that resveratrol increased survival of the mice and insulin sensitivity. Resveratrol treatment also improved mitochondria activity and motor performance in the mice. They saw a clear trend towards increased survival and insulin sensitivity.

The report caused a quite a bit of excitement – suddenly there was the possibility that we could eat anything we wanted and this amazing chemical would safe us from any negative consequences.

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Source: Nature

That report was proceeded by numerous studies demonstrating that resveratrol could extend the life-span of various micro-organisms, and it was achieving this by activating a family of genes called sirtuins (specifically Sir1 and Sir2) (Click herehere and here for more on this).

Subsequent to these reports, there have been numerous scientific publications suggesting that resveratrol is capable of all manner of biological miracles.

Wow! So what is resveratrol?

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Do you prefer your wine in pill form? Source: Patagonia

Resveratrol is a chemical that belongs to a group of compounds called polyphenols. They are believed to act like antioxidants. Numerous plants produce polyphenols in response to injury or when the plant is under attack by pathogens (microbial infections).

Fruit are a particularly good source of resveratrol, particularly the skins of grapes, blueberries, raspberries, mulberries and lingonberries. One issue with fruit as a source of resveratrol, however, is that tests in rodents have shown that less than 5% of the oral dose was observed as free resveratrol in blood plasma (Source). This has lead to the extremely popular idea of taking resveratrol in the form of wine, in the hope that it could have higher bioavailability compared to resveratrol in pill form. Red wines have the highest levels of Resveratrol in their skins (particularly Mabec, Petite Sirah, St. Laurent, and pinot noir). This is because red wine is fermented with grape skins longer than is white wine, thus red wine contains more resveratrol.


EDITOR’S NOTE: Sorry to rain on the parade, but it is important to note here that red wine actually contains only small amounts of resveratrol – less than 3-6 mg per bottle of red wine (750ml). Thus, one would need to drink a great deal of red wine per day to get enough resveratrol (the beneficial effects observed in the mouse study described above required 20mg/kg of resveratrol per day. For a person weighting 80kg, this would equate to 1.6g per day or approximately 250 750ml bottles). 

We would like to suggest that consuming red wine would NOT be the most efficient way of absorbing resveratrol. And obviously we DO NOT recommend any readers attempt to drink 250 bottles per day (if that is even possible). 

The recommended daily dose of resveratrol should not exceed 250 mg per day over the long term (Source). Resveratrol might increase the risk of bleeding in people with bleeding disorders. And we recommend discussing any change in treatment regimes with your doctor before starting.


So what did they find in the Alzheimer’s clinical study?

Well, the report we will look at today is actually a follow-on to published results from a phase 2/safety clinical trial that were reported in 2015:

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Title: A randomized, double-blind, placebo-controlled trial of resveratrol for Alzheimer disease.
Authors: Turner RS, Thomas RG, Craft S, van Dyck CH, Mintzer J, Reynolds BA, Brewer JB, Rissman RA, Raman R, Aisen PS; Alzheimer’s Disease Cooperative Study.
Title: Neurology. 2015 Oct 20;85(16):1383-91.
PMID: 26362286          (This article is OPEN ACCESS if you would like to read it)

The researchers behind the study are associated with the Georgetown research group that conducted the initial Nilotinib clinical study in Parkinson’s disease (Click here for our post on this).

The investigators conducted a randomized, placebo-controlled, double-blind, multi-center phase 2 trial of resveratrol in individuals with mild to moderate Alzheimer disease. The study lasted 52 weeks and involved 119 individuals who were randomly assigned to either placebo or resveratrol 500 mg orally daily treatment.

EDITOR’S NOTE: We appreciate that is daily dose exceeds the recommended daily dose mentioned above, but it is important to remember that the participants involved in this study were being closely monitored by the study investigators.

Brain imaging and samples of cerebrospinal fluid (the liquid within which the brain sits) were collected at the start of the study and after completion of treatment.

The most important result of the study was that resveratrol was safe and well-tolerated. The most common side effect was feeling nausea and diarrhea in approximately 42% of individuals taking resveratrol (curiously 33% of the participants blindly taking the placebo reported the same thing). There was also a weight loss effect between the groups, with the placebo group gaining 0.5kg on average, while the resveratrol treated group lost 1kg on average.

The second important take home message is that resveratrol crossed the blood–brain barrier in humans. The blood brain barrier prevents many compounds from having any effect in the brain, but it does not stop resveratrol.

The investigators initially found no effects of resveratrol treatment in various Alzheimer’s markers in the cerebrospinal fluid. Not did they see any effect in brain scans, cognitive testing, or glucose/insulin metabolism. The authors were cautious about their conclusions based on these results, however, as the study was statistically underpowered (that is to say, there were not enough participants in the various groups) to detect clinical benefits. They recommended a larger study to determine whether resveratrol is actually beneficial.

While exploring the idea of a larger study, the researchers have re-analysed some of the data, and that brings us to the report we want to review today:

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Title: Resveratrol regulates neuro-inflammation and induces adaptive immunity in Alzheimer’s disease.
Authors: Moussa C, Hebron M, Huang X, Ahn J, Rissman RA, Aisen PS, Turner RS.
Journal: J Neuroinflammation. 2017 Jan 3;14(1):1. doi: 10.1186/s12974-016-0779-0.
PMID: 28086917       (This article is OPEN ACCESS if you would like to read it)

In this report, the investigators conducted a retrospective study re-examining the cerebrospinal fluid and blood plasma samples from a subset of subjects involved in the clinical study described above. In this study, they only looked at the subjects who started with very low levels in the cerebrospinal fluid of a protein called Aβ42.

Amyloid beta (or Aβ) is the bad boy/trouble maker of Alzheimer’s disease; considered to be critically involved in the disease. A fragment of this protein (called Aβ42) begin clustering in the brains of people with Alzheimer’s disease and as a result, low levels of Aβ42 in cerebrospinal fluid have been associated with increased risk of Alzheimer’s disease and considered a possible biomarker of the condition (Click here to read more on this).

The resveratrol study investigators collected all of the data from subjects with cerebrospinal fluid levels of Aβ42 less than 600 ng/ml at the start of the study. This selection criteria gave them 19 resveratrol-treated and 19 placebo-treated subjects.

In this subset re-analysis study, resveratrol treatment appears to have slowed the decline in cognitive test scores (the mini-mental status examination), as well as benefiting activities of daily living scores and cerebrospinal fluid levels of Aβ42.

One of the most striking results from this study is the significant decrease observed in the cerebrospinal fluid levels of a protein called Matrix metallopeptidase 9 (or MMP9) after resveratrol treatment. MMP9 is slowly emerged as an important player in several neurodegenerative conditions, including Parkinson’s disease (Click here to read more on this). Thus the decline observed is very interesting.

This re-analysis indicates beneficial effects in some cases of Alzheimer’s as a result of taking resveratrol over 52 weeks. The researchers concluded that the findings of this re-analysis support the idea of a larger follow-up study of resveratrol in people with Alzheimer’s disease.

Ok, but what research has been done on resveratrol in Parkinson’s disease?

Yes, good question.

One of the earliest studies looking at resveratrol in Parkinson’s disease was this one:

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Title: Neuroprotective effect of resveratrol on 6-OHDA-induced Parkinson’s disease in rats.
Authors: Jin F, Wu Q, Lu YF, Gong QH, Shi JS.
Journal: Eur J Pharmacol. 2008 Dec 14;600(1-3):78-82.
PMID: 18940189

In this study, the researchers used a classical rodent model of Parkinson’s disease (using the neurotoxin 6-OHDA). One week after inducing Parkinson’s disease, the investigators gave the animals either a placebo or resveratrol (at doses of 10, 20 or 40 mg/kg). This treatment regime was given daily for 10 weeks and the animals were examined behaviourally during that time.

The researchers found that resveratrol improved motor performance in the treated animals, with them demonstrating significant results as early as 2 weeks after starting treatment. Resveratrol also reduced signs of cell death in the brain. The investigators concluded that resveratrol exerts a neuroprotective effect in this model of Parkinson’s disease.

Similar results have been seen in other rodent models of Parkinson’s disease (Click here and here to read more).

Subsequent studies have also looked at what effect resveratrol could be having on the Parkinson’s disease associated protein alpha synuclein, such as this report:

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Title: Effect of resveratrol on mitochondrial function: implications in parkin-associated familiarParkinson’s disease.
Authors: Ferretta A, Gaballo A, Tanzarella P, Piccoli C, Capitanio N, Nico B, Annese T, Di Paola M, Dell’aquila C, De Mari M, Ferranini E, Bonifati V, Pacelli C, Cocco T.
Journal: Biochim Biophys Acta. 2014 Jul;1842(7):902-15.
PMID: 24582596                     (This article is OPEN ACCESS if you would like to read it)

 

In this study, the investigators collected skin cells from people with PARK2 associated Parkinson’s disease.

What is PARK2 associated Parkinson’s disease?

There are about 20 genes that have been associated with Parkinson’s disease, and they are referred to as the PARK genes. Approximately 10-20% of people with Parkinson’s disease have a genetic variation in one or more of these PARK genes (we have discussed these before – click here to read that post).

PARK2 is a gene called Parkin. Mutations in Parkin can result in an early-onset form of Parkinson’s disease. The Parkin gene produces a protein which plays an important role in removing old or sick mitochondria.

Hang on a second. Remind me again: what are mitochondria?

We have previously written about mitochondria (click here to read that post). Mitochondria are the power house of each cell. They keep the lights on. Without them, the lights go out and the cell dies.

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Mitochondria and their location in the cell. Source: NCBI

You may remember from high school biology class that mitochondria are bean-shaped objects within the cell. They convert energy from food into Adenosine Triphosphate (or ATP). ATP is the fuel which cells run on. Given their critical role in energy supply, mitochondria are plentiful and highly organised within the cell, being moved around to wherever they are needed.

Another Parkinson’s associated protein, Pink1 (which we have discussed before – click here to read that post), binds to dysfunctional mitochondria and then grabs Parkin protein which signals for the mitochondria to be disposed of. This process is an essential part of the cell’s garbage disposal system.

Park2 mutations associated with early onset Parkinson disease cause the old/sick mitochondria are not disposed of correctly and they simply pile up making the cell sick. The researchers that collected the skin cells from people with PARK2 associated Parkinson’s disease found that resveratrol treatment partially rescued the mitochondrial defects in the cells. The results obtained from these skin cells derived from people with early-onset Parkinson’s disease suggest that resveratrol may have potential clinical application.

Thus it would be interesting (and perhaps time) to design a clinical study to test resveratrol in people with PARK2 associated Parkinson’s disease.

So why don’t we have a clinical trial?

Resveratrol is a chemical that falls into the basket of un-patentable drugs. This means that big drug companies are not interested in testing it in an expensive series of clinical trials because they can not guarantee that they will make any money on their investment.

There was, however, a company set up in 2004 by the researchers behind the original resveratrol Nature journal report (discussed at the top of this post). That company was called “Sirtris Pharmaceuticals”.

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Source: Crunchbase

Sirtris identified compounds that could activate the sirtuins family of genes, and they began testing them. They eventually found a compound called SRT501 which they proposed was more stable and 4 times more potent than resveratrol. The company went public in 2007, and was subsequently bought by the pharmaceutical company GlaxoSmithKline in 2008 for $720 million.

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Source: Xconomy

From there, however, the story for SRT501… goes a little off track.

In 2010, GlaxoSmithKline stopped any further development of SRT501, and it is believed that this decision was due to renal problems. Earlier that year the company had suspended a Phase 2 trial of SRT501 in a type of cancer (multiple myeloma) because some participants in the trial developed kidney failure (Click here to read more).

Then in 2013, GlaxoSmithKline shut down Sirtris Pharmaceuticals completely, but indicated that they would be following up on many of Sirtris’s other sirtuins-activating compounds (Click here to read more on this).

Whether any of those compounds are going to be tested on Parkinson’s disease is yet to be determined.

What we do know is that the Michael J Fox foundation funded a study in this area in 2008 (Click here to read more on this), but we are yet to see the results of that research.

We’ll let you know when we hear of anything.

So what does it all mean?

Summing up: Resveratrol is a chemical found in the skin of grapes and berries, which has been shown to display positive properties in models of neurodegeneration. A recent double blind phase II efficacy trial suggests that resveratrol may be having positive benefits in Alzheimer’s disease.

Preclinical research suggests that resveratrol treatment could also have beneficial effects in Parkinson’s disease. It would be interesting to see what effect resveratrol would have on Parkinson’s disease in a clinical study.

Perhaps we should have a chat to the good folks at ‘CliniCrowd‘ who are investigating Mannitol for Parkinson’s disease (Click here to read more about this). Maybe they would be interested in resveratrol for Parkinson’s disease.


ONE LAST EDITOR’S NOTE: Under absolutely no circumstances should anyone reading this material consider it medical advice. The material provided here is for educational purposes only. Before considering or attempting any change in your treatment regime, PLEASE consult with your doctor or neurologist. SoPD can not be held responsible for actions taken based on the information provided here. 


The banner for today’s post was sourced from VisitCalifornia

A new theory of Parkinson’s disease

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The great American baseball legend, Yogi Berra, once said: “In theory, there is no difference between theory and practice. But in practice, there is.”

Silly as it reads, there is a great deal of truth to that statement.

In science, we very quickly chase after a particular theory as soon as a little bit of evidence is produced that supports it. Gradually, these theories become our basic understanding of a situation, until someone points out the holes in the theory and we have to revise it.

A new theory of Parkinson’s disease has recently been proposed. In today’s post we will review what the theory is suggesting and what evidence there is to support it.


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“I still say it’s only a theory”. Source: NewYorker

In the age of ‘alternative facts’, it is always important to remember that we don’t know as much as we think we do. In fact, much of our modern world still relies on a kind of faith rather than actual ‘facts’. For example, we take a particular type of medicine, because it has worked for some people in the past, not because it will definitely make us better.

And the same applies to our understanding of neurodegenerative conditions, like Parkinson’s disease. Based on all the evidence we have collected thus far, we have theories of how Parkinson’s disease may be progressing. But there are always exceptions to the rule, and these force us to refine or reconsider our theories.

Recently a refinement to our theory of Parkinson’s disease has been suggested.

Who has suggested it?

This is Prof Ole Isacson.

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Source: Crunchbase

He’s a dude.

He is is a Professor of Neurology at Harvard Medical School, and Chief Scientific Officer of the Neuroscience Research Unit and Senior Vice President at the pharmaceutical company Pfizer.

And this is Dr Simone Engelender.

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Source: Rappaport

She’s awesome as well.

She is Associate Professor of Molecular Pharmacology at the Rappaport Family Institute for Research in the Medical Sciences in Haifa, Israel.

Together they have proposed a new theory of Parkinson’s disease that has the research community talking:

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Title: The Threshold Theory for Parkinson’s Disease.
Authors: Engelender S, Isacson O.
Journal: Trends Neurosci. 2017 Jan;40(1):4-14.
PMID: 27894611

The new theory proposes that Parkinson’s disease may actually be a ‘systemic condition’ (that is, affecting cells everywhere at the same time), but the clinical features – such as motor issues – only appear as certain thresholds are passed in the affected populations of neurons in the brain.

What does that mean?

Wait a minute. Let’s start at the beginning.

Before discussing what the new theory suggests, shall we first have a look at what the old theories proposed?

Ok, what did the old theory propose?

This is Prof Heiko Braak:

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Source – Memim.com

He’s pretty cool too. Nice guy.

Many years ago, Prof Braak – a German neuroanatomist – sat down and examined hundreds of postmortem brains from people with Parkinson’s disease.

He had collected brains from people at different stages of Parkinson’s disease – from just after being diagnosed to having had the condition for decades – and he was looking for any kind of pattern that might explain where and how the disease starts. His research led to what is referred to as the “Braak stages of Parkinson’s disease” – a six step explanation of how the disease spreads up from the brain stem and into the rest of the brain (Click here to read more about this).

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The Braak stages of PD. Source: Nature

Braak’s results also led him to propose that Parkinson’s disease may actually begin in the brain stem (which connects the brain to the spinal cord) and the disease slowly works it’s way up into the brain.

That is the ‘ascending’ theory of Parkinson’s disease.

This idea has been further adapted by Braak and others with the discovery of Parkinson’s disease features in the gut (we have discussed this in previous posts – Click here and here to read those posts).

But how does the disease actually spread?

Good question.

The spread of the condition is believed to be due to the protein alpha synclein being passed between cells in some manner. This idea stemmed from the analysis of the brains of people with Parkinson’s disease who received cell transplantation therapy in the 1980-90’s. After those people passed away (due to natural causes), their brains were analysed and it was discovered that some of the cells in the transplants (1-5%) have Lewy bodies in them (Lewy bodies are one of the hallmarks of Parkinson’s disease, dense circular clusters of proteins including alpha synuclein). This suggests that the disease is passed on to the healthy transplanted cells in some way.

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Photos of neurons from the post-mortem brains of people with Parkinson’s that received transplants. White arrows in the images above indicate lewy bodies inside transplanted cells. Source: The Lancet

So the research community has been working with the idea of an ‘ascending’ theory of Parkinson’s disease, and the spreading of the condition via the passing of alpha synuclein from cell to cell. And this theory has been fine,…

Why do I feel like there’s a ‘but’ coming?

Because there is a ‘but’ coming.

And it’s a big BUT.

But as Prof Isacson and Dr Engelender point out there are some holes in this theory.

Some big holes.

For example, in a 2008 study of 71 postmortem brains from people with Parkinson’s disease, 47% of the cases did not fit the predicted ‘Braak theory’ spread of alpha synuclein, and 7% of those cases did not have any cell loss in the dorsal motor nucleus (one of the first sites of damage in the Braak theory – Click here to read more).

Ok, so the theory is not perfect…what are Prof Isacson and Dr Engelender proposing instead?

They suggest that alpha synuclein accumulation starts at about the same time in nerve cells throughout the body, but the different groups of nerve cell differ in how much toxicity they can handle.

Some of these groups of cells can handle a lot (and more than half of the cells need to be lost before clinical features begin to appear), while others have a lower ‘threshold’ (only a few cells need to die before symptoms appear).

Prof Isacson and Dr Engelender argue that the nerve cells around the gut, for example, have a lower reserve (or total number), and, therefore, symptoms related to the gut become more obvious sooner as those cells die off or become less efficient. This lower threshold is in contrast to the more well known cell loss of the dopamine producing neurons in the midbrain, where approximately 50-70 percent of the dopamine neurons disappear before the classical motor features of Parkinson’s start to appear. Their theory suggests that this part of the brain has a larger reserve, and thus higher threshold.

Hence the reason why this is being called the ‘threshold theory’.

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Some groups of cells may have a higher threshold in Parkinson’s disease. Source: Cell

Some cells may have a low threshold and only require a few cells to be lost before the clinical features associated with those cells begin to appear. These symptoms would obviously appear earlier than those features associated with a high threshold population of cells, which required substantial loss before symptoms appear.

This idea would explain differing results seen in research findings regarding, for example, vagotomies (the cutting of the vagus nerve to the gut – click here to read more about this). This new theory would suggest that the procedure might not have any impact at all on lowering the risk of Parkinson’s disease.

Both scientists insist that searching for treatments that slow or block the aggregation of alpha synuclein is still necessary.

“Instead of studying how proteins move from one neuron to another and searching for compounds that prevent the ‘spread’ of aggregated alpha-synuclein, we need to study why alpha-synuclein accumulates within neurons and how these neurons die in the disease, and search for compounds that prevent the general neuronal dysfunction,” – Dr Engelender

(Source: Science Daily)

So are there any problems with this new theory?

The new theory is a very interesting idea and deserves consideration. It solves some of the problems with the “ascending theory” discussed further above. But it also faces some of the same problems that the ascending theory has to deal with.

For example, in one large autopsy study which investigated 904 brains, the investigators blindly collected all of the brains that had alpha synuclein present in the groups of neurons that are affected in Parkinson’s disease (eg. the dorsal motor nucleus of vagus, substantia nigra, and/or basal forebrain nuclei.). They found that alpha synuclein was observed in 11.3% (or 106 cases). But when the researchers then looked at the clinical notes associated with those cases, only 32 (30%) had been diagnosed with a neurodegenerative disorder. The rest had demonstrated no clinical features.

Another study found that 8.3% of the aged control brains had alpha synuclein present in them. In addition, the presence of alpha synuclein is not specific to Parkinson’s disease – approximately 50% of people who die with Alzheimer’s disease have been found to have Lewy bodies. These results suggest that alpha synuclein aggregation can be present in both healthy and diseased brains. But if this is so, what role is alpha synuclein playing in Parkinson’s disease?

(You see the sort of problems we are dealing with in research when trying to come up with a theory of how something complicated is actually working?)

What does it all mean?

The central job of a scientist is to test hypotheses.

A hypothesis is a true or false statement (for example, hypothesis: the sun will come up tomorrow – easy to test as the sun either will or won’t come up; the statement is either true or false). In building one hypothesis on top of another hypothesis, we develop theories about how the world around us works.

Sometimes our hypotheses can unwittingly take us in a particular direction, depending on different variables. The danger in this process (one which must be met with discipline and control procedures) is that one can start to look for results that support a hypothesis or theory. It is a very human characteristic to become blind to any evidence to the contrary.

A new theory of Parkinson’s disease has been proposed. It suggests that rather than the condition starting in one location and progressively moving higher into the brain, Parkinson’s disease may actually start everywhere and it is the varying levels of tolerance between different types of cells that determines which cells die first.

It is certainly a new take of the available evidence and the research community is considering it. It will be interesting to see what kind of feedback results from this article, and we will post updates on that feedback as they become available.


The banner for today’s post was sourced from Sott

A yeast model of Parkinson’s disease

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When I say the word ‘yeast’, you might think of making bread or beer.

One does not automatically think of Parkinson’s disease.

But yeast has actually been incredibly useful in enhancing our understanding of the genetics of Parkinson’s disease, and may well now provide us with novel treatments for the condition. In today’s post we will discuss how yeast research is leading the way for Parkinson’s disease.


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Prof Susan Lindquist. Source: WallStreetJournal

It was with sadness that we heard about the passing of Prof Susan Lindquist in October last year. She was truly a pioneer in the field of molecular biology. In addition to advancing our understanding of gene functioning in degenerative diseases like Parkinson’s disease and Alzheimer’s, she also started a company, Yumanity, which is currently testing new drugs to tackle these conditions. Hopefully her legacy will have enormous impact for the millions of people around the world struggling with these conditions.

And that legacy all started with a bold (some even called it ‘crazy’) idea.

It involved yeast.

What is yeast?

Quite possibly the earliest domesticated species, yeast is a single-celled microorganism, traditionally classified as a member of the fungus kingdom. The evolutionary lineage of yeast dates back hundreds of millions of years old and there are at least 1500 species of yeast (Source: Wikipedia).

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The cellular structure of yeast. Source: Biocourseware

More importantly, yeast is one of the most centrally important model organisms used in modern biological research, representing one of the most thoroughly researched organisms in the world.

We know more about the biology of yeast than we do about ourselves!

And this statement is made further evident as researchers use yeast to produce the world’s first synthetic organism (an organism for which the genome has been designed or engineered). By the end of 2017, the Synthetic Yeast 2.0 consortium plans to have produced a new form of yeast in which all 16 chromosomes will have been made in the lab (for more on this, read this STAT article).

Why do scientists like studying yeast?

The main reason is that yeast cells are very similar to human cells, but they grow a lot faster (human cells on average divide a rate of about once every 12 hours, while yeast cells divide every two hours). Yeast is similar to human cells in that it has all of the eukaryote structures, including a nucleus, cytoplasm, and mitochondria (eukaryote meaning a cell with a nucleus).

Yeast has played a fundamental role in many major scientific discoveries since the early 1900s. In 1907, German scientist Edward Buchner won the Nobel Prize in Chemistry for research involving yeast extract and fermentation. Ninety one years later (2006), Roger D. Kornberg won the same prize for his work on DNA transcription using yeast.

Yeast was the first eukaryote to have its genome (DNA) fully sequenced (in 1996). Yeast is literally leading the way in biological research.

So what has this got to do with Parkinson’s disease?

This is where Prof Susan Lindquist comes into the story.

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Source: Youtube

In the early 2000s, she suggested the idea of using yeast to look at neurodegenerative conditions like Parkinson’s disease. It was a wild concept. Talking to the New York Times in 2007, she said “Even people in my laboratory thought we were crazy to try to study neurodegenerative diseases with a yeast cell. It’s not a neuron”.

But they persevered and in 2003 they published this research report in the journal Science:

yeast

Title: Yeast genes that enhance the toxicity of a mutant huntingtin fragment or alpha-synuclein.
Authors: Willingham S, Outeiro TF, DeVit MJ, Lindquist SL, Muchowski PJ.
Journal: Science. 2003; 302(5651):1769-72.
PMID: 14657499

In this study, the researchers conducted a genome-wide screens of mutant genes in yeast to identify genes that enhanced the toxic effects of the mutant huntingtin gene or alpha-synuclein protein. That is to say, they randomly mutated (made un-operational) just one gene per yeast cell, and these yeast cells either had the mutant huntingtin gene (which causes the neurodegenerative condition of Huntington’s disease) or too much alpha synuclein (which causes protein clumping in the yeast cells). Using this approach, they could determine which genes were responsible for increasing the negative effects of the mutant huntington gene or the alpha synuclein protein.

Of the 4850 yeast genes that the researcher mutated (and can we just point out that that is A LOT of work!!!), 52 were identified that exaggerated the affect of the mutant huntingtin gene and 86 increased sensitivity to alpha-synuclein (curiously, only one mutant gene resulted in increased sensitivity to both).

When they looked at the known functions of 86 genes that were increasing the sensitivity to alpha synuclein, the researchers found that most of them were involved in the processes of lipid metabolism (the synthesis and degradation of lipids) and vesicle-mediated transport (this occurs at the tips of neural branches – where alpha synuclein is located). Alpha synuclein is known to be involved with lipid metabolism (Click here and here for more on this). This reenforced the belief with the researchers that yeast could be used to assess disease relevant pathways – this study gave them the ‘proof of concept’.

In addition, the majority of the genes had human ‘orthologs’ (genes in different species that evolved from a common ancestral gene), meaning that the findings of yeast studies could potentially be translated to higher order creatures, like humans. The researchers concluded that they had found cell autonomous genes that are relevant to Parkinson’s disease.

With the publication of this work, people in Prof Lindquist’s lab were probably thinking the idea wasn’t so crazy anymore.

And this first publication led to many more, such as this report which was published in the same journal in 2006:

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Title: Alpha-synuclein blocks ER-Golgi traffic and Rab1 rescues neuron loss in Parkinson’s models.
Authors: Cooper AA, Gitler AD, Cashikar A, Haynes CM, Hill KJ, Bhullar B, Liu K, Xu K, Strathearn KE, Liu F, Cao S, Caldwell KA, Caldwell GA, Marsischky G, Kolodner RD, Labaer J, Rochet JC, Bonini NM, Lindquist S.
Journal: Science. 2006 Jul 21;313(5785):324-8.
PMID: 16794039      (This article is OPEN ACCESS if you would like to read it)

In this study, the researchers doubled the amount of alpha synuclein that yeast cells produce and they observed that the cell stopped growing and started to die. They then looked at the earliest cellular events following theover production of alpha synuclein and they noticed that there was a blockage in the endoplasmic reticulum (ER)-to-Golgi vesicular trafficking.

Yes, I know what you are going to ask: What is ER-to-Golgi vesicular trafficking?

The endoplasmic reticulum (or ER) is a network of tubules connected to the nucleus. It is involved in the production of proteins and lipids, which are then transported to the Golgi apparatus which then modifies them, sorts them and and packs them into small bags called vesicles. These vesicles can then be taken to the cell membrane where the proteins are released to do their jobs.

ergolgi

The ER to Golgi pathway. Source: Welkescience

Now the fact that too much alpha synuclein was blocking this pathway was interesting, but the researchers wanted to go further. They conducted another genome-wide screens of genes in yeast to identify genes that could rescue this blockage – BUT this time, instead of mutating genes, the researchers randomly over produced one protein (and there was 3000 of them!!!) in each cell. Because the overproduction of alpha synuclein kills the yeast cells, all the researchers had to do was wait until the end of the experiment and determine which protein was over produced in the surviving cells.

And this led them to a protein called RAB1.

RAB1 is a protein that is critical to the transportation of proteins in cells. The researchers next tested the ability of RAB1 to rescue dopamine cells in Drosophila (flies), Caenorhabditis elegans (microscopic worms), and cell culture models of Parkinson’s disease and they found that it was able to rescue the cells in all three cases. While this result was very interesting, it also provided full validation of the approach that Prof Lindquist and her colleagues were taking using yeast cells to find new therapies for neurodegenerative conditions, like Parkinson’s disease.

But Prof Lindquist and her colleagues didn’t stop there.

Over the next decade numerous research reports were published taking advantage of this approach, including these two reports which appeared back-to-back in the journal Science:

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Title: Identification and rescue of α-synuclein toxicity in Parkinson patient-derived neurons.
Authors: Chung CY, Khurana V, Auluck PK, Tardiff DF, Mazzulli JR, Soldner F, Baru V, Lou Y, Freyzon Y, Cho S, Mungenast AE, Muffat J, Mitalipova M, Pluth MD, Jui NT, Schüle B, Lippard SJ, Tsai LH, Krainc D, Buchwald SL, Jaenisch R, Lindquist S.
Journal: Science. 2013 Nov 22;342(6161):983-7.
PMID: 24158904

And:

lindq2

Title: Yeast reveal a “druggable” Rsp5/Nedd4 network that ameliorates α-synuclein toxicity in neurons.
Authors: Tardiff DF, Jui NT, Khurana V, Tambe MA, Thompson ML, Chung CY, Kamadurai HB, Kim HT, Lancaster AK, Caldwell KA, Caldwell GA, Rochet JC, Buchwald SL, Lindquist S.
Journal: Science. 2013 Nov 22;342(6161):979-83.
PMID: 24158909

In these reports, Prof Lindquist and colleagues tested whether some of the proteins that had come up in their various screens could actually have positive benefits in human cells, specifically induced pluripotent stem (iPS) cells (which we have discussed before – click here to read that post). The researchers grew brains cells (neurons and glial cells) from the iPS cells derived from people who suffered from Parkinson’s disease with dementia. These cells exhibited a number of features that indicated that they were not healthy. From their yeast screens, the researchers identified a protein called Nedd4 that reversed the pathologic features in these neurons.

Nedd4 is an E3 ubiquitin-protein ligase, which is a protein involved in the removal of old or damaged proteins from a cell. It is part of the garbage disposal process. Importantly, Nedd4 has been shown to label alpha synuclein for disposal (Click here to read more about this) and it is also present in Lewy Bodies – the circular clusters of proteins present in the brains of people with Parkinson’s disease. Importantly, it is a ‘druggable’ target. Nedd4 has been considered a therapeutic target for cancer (Click here to read more on this).

More recently (and following the passing of Prof Lindquist) the group has published two research reports back-to-back in the journal Cell Systems:

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Title: Genome-Scale Networks Link Neurodegenerative Disease Genes to α-Synuclein through Specific Molecular Pathways.
Authors: Khurana V, Peng J, Chung CY, Auluck PK, Fanning S, Tardiff DF, Bartels T, Koeva M, Eichhorn SW, Benyamini H, Lou Y, Nutter-Upham A, Baru V, Freyzon Y, Tuncbag N, Costanzo M, San Luis BJ, Schöndorf DC, Barrasa MI, Ehsani S, Sanjana N, Zhong Q, Gasser T, Bartel DP, Vidal M, Deleidi M, Boone C, Fraenkel E, Berger B, Lindquist S.
Journal: Cell Syst. 2017 Jan 25. pii: S2405-4712(16)30445-8.
PMID: 28131822        (This article is OPEN ACCESS if you would like to read it)

And:

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Title: In Situ Peroxidase Labeling and Mass-Spectrometry Connects Alpha-Synuclein Directly to Endocytic Trafficking and mRNA Metabolism in Neurons.
Authors: Chung CY, Khurana V, Yi S, Sahni N, Loh KH, Auluck PK, Baru V, Udeshi ND, Freyzon Y, Carr SA, Hill DE, Vidal M, Ting AY, Lindquist S.
Journal: Cell Syst. 2017 Jan 25. pii: S2405-4712(17)30002-9.
PMID: 28131823

In these reports, Prof Lindquist and colleagues systematically mapped out molecular pathways underlying the toxic effects of alpha-synuclein. They applied their yeast derived 332 genes that impact alpha-synuclein toxicity, and linked them to multiple Parkinson’s-associated genes and druggable targets, using software called TransposeNet.

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Source: Cell

The investigators then validated some of the connections in human iPS cells derived from people with Parkinson’s disease, confirming that some of the Parkinson’s disease-related genetic interactions observed in yeast are ‘conserved’ (that is maintained across evolution) to humans. And these findings fully vindicated Prof Lindquist’s ‘crazy’ idea of using yeast cells to investigate neurodegenerative disease.

In the second report, the researchers identified 225 proteins in close physical proximity to alpha-synuclein in neurons using a new technique (called ascorbate peroxidase (APEX) labeling – let’s just say it’s complicated, but if you’d like to read more about it, Click here). Many of those 225 proteins were well known to the researchers being involved with activities in vesicles and synaptic terminals, where alpha synuclein is often found. But the researchers also found microtubule-associated proteins (including tau) rubbing shoulders with alpha-synuclein, as well as proteins involved with mRNA binding, processing, and translation (which they were not expecting). Thus, not only has Prof Lindquist’s yeast model of Parkinson’s disease provided us with novel therapeutic targets, but also opened new avenues of research related to alpha synuclein functioning.

 

And there is now a ‘yeast’ biotech company?

It is called Yumanity.

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Yumanity. Source: ScientificAmerican

Started in December 2014, with $45 million in funding, Yumanity is focused on determining new targets for neurodegenerative conditions in yeast cells, testing those new targets in human cells, and then moving towards clinical trials with the best candidates. To date, they have not announced any clinical trial candidates, but they working on compounds that are targeting the NEDD4 pathway in Parkinson disease (discussed above). We will be watching this company with great interest.

So what does it all mean?

Back in the early 2000s, Prof Lindquist and her team asked a simple but strange question:

Can we use our knowledge of yeast genetics to study neurodegeneration?

We now know that the answer is ‘yes’. The small single cell organism that most of us associate with baking and beer, shares enough genetics with us that we can use it as an assay for investigating molecular pathways involved with diseases of the brain. And in the not so distant future, this simple little organism may be providing us with new treatments and therapies for those diseases.

As we suggested at the start of this post, Prof Lindquist has left an amazing legacy. If Yumanity can move a new drug into clinical trials for Parkinson’s disease, it will only further strengthen that legacy.

Susan Lee Lindquist – June 5, 1949 to October 27, 2016


The banner for today’s post was sourced from NewEuropeans

The Journal of Parkinson’s disease – special issue

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Our policy at the SoPD is not to advertise or endorse commercial products or services. This is to avoid any ethical or conflict of interest situations.

Every now and then, however, we see something that we believe will be of interest and value to the Parkinson’s community…aaand we bend our policy rule book.


Today the Journal of Parkinson’s disease released a “200 years of Parkinson’s disease” OPEN ACCESS special issue of their journal which highlights some of the major discoveries in the field of Parkinson’s disease research.

Critically, the articles provide insights into how the discoveries were made, and they are written by some of the biggest names in the Parkinson’s research community (many of whom were actually there when the discoveries were made).

The issue has articles dealing with topics including:

Click here to see all of the articles in this special issue.

We fully recommend readers take advantage of this OPEN ACCESS issue and learn about how some of these great discoveries were made.

Happy reading.


Full disclosure: The Journal of Parkinson’s disease is a product of IOS Press. The SoPD has not been approached by or made any offers to IOS Press or anyone at the Journal of Parkinson’s disease. We merely thought that the material in this particular OPEN ACCESS issue would be of interest to our readers.


The banner for today’s post was sourced from the Journal of Parkinson’s disease

The red headed mice of Boston

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Recently scientists have found a possible link in the curious relationship of red hair, melanoma and Parkinson’s disease.

It involves red headed mice (not a typo – you read that correctly).

In today’s post we will discuss the new research and explain what it means for Parkinson’s disease.


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Red or ginger hair. Source: theLocal

We have previously discussed the curious association between red hair and Parkinson’s disease (Click here for that post).

We have also previously discussed the curious association between melanoma and Parkinson’s disease (Click here for that post).

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Melanoma. Source: Wikipedia

Basically, people with red hair are more vulnerable to Parkinson’s disease that dark haired people, and people with a history of melanoma (skin cancer) are more likely to develop Parkinson’s disease than people with no history.

And given that people with red hair are generally more vulnerable to melanoma that dark haired people, you can understand why scientists have recently been very interested in this curious triangle of seemingly unrelated biological features.

Recently, however, scientists in Boston (USA) have provided evidence that the genetic mutation which causes red hair and increases the risk of melanoma, might also make the brain more vulnerable to Parkinson’s disease.

Red hair is caused by a genetic mutation?

Before we answer this question: the word ‘mutation’ carries a negative connotation thanks to it’s use in popular media and films. In biology, researchers prefer to use the word genetic ‘variation’. And EVERYONE has variations. They are what makes each of us unique. A father will pass on many of his own genetic variations to his son, but there will also be 50-100 spontaneous variations. And this is how, red hair can sometimes pop up in a family with little history of it.

Ok, so red hair is caused by a genetic variation?

Yes.

Red hair, which occurs naturally in 1–2% of the general population (though there are some regional/geographical variation), results from one of several genetic variations. Approximately 80% of people with red hair have a variation in a gene called melanocortin-1 receptor (or MC1R). Another gene associated with red hair is called HCL2 – ‘Hair colour 2’.

So what did the researchers find?

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Title: The melanoma-linked “redhead” MC1R influences dopaminergic neuron survival.
Authors: Chen X, Chen H, Cai W, Maguire M, Ya B, Zuo F, Logan R, Li H, Robinson K, Vanderburg CR, Yu Y, Wang Y, Fisher DE, Schwarzschild MA.
Journal: Ann Neurol. 2016 Dec 26. doi: 10.1002/ana.24852. [Epub ahead of print]
PMID: 28019657

In their study, the researchers have investigated mice that carry a mutation of the MC1R gene (thus inactivating the gene – and yes, these mice have red/ginger fur!). They noticed that the mice displayed a progressive decline in their locomotor activity, moving around significantly less than non-red furred control mice at 8 months of age. The MC1R mutant mice also displayed a reduction in the number of dopamine producing neurons in the brain, when compared to the non-red furred controls (dopamine a chemical in the brain that helps to regulate movement).

The MC1R mutant mice were more vulnerable to toxin induced models of Parkinson’s disease (both 6OHDA and MPTP), but (most interestingly) when the researchers used a substance that binds to MC1R and initiates a response (an MC1R agonist called BMS-470539) they found that this treatment improved the survival of the dopamine producing cells in the brain.

The researchers are now seeking to further understand how the loss of MC1R renders the dopamine cells more vulnerable, and follow up the finding that MC1R agonists are neuroprotective.

Has there ever been any other evidence to suggest that MC1R is neuroprotective?

No. To our knowledge this is the first evidence that targeting MC1R could be a novel therapeutic strategy in a brain related condition (there has been some evidence of MC1R activation having beneficial effects in other parts of the body – click here for more on this).

And there are some indications as to how this positive effect could be working:

nurr1-2
Title: Melanocortin-1 receptor signaling markedly induces the expression of the NR4A nuclear receptor subgroup in melanocytic cells.
Authors: Smith AG, Luk N, Newton RA, Roberts DW, Sturm RA, Muscat GE.
Journal: J Biol Chem. 2008 May 2;283(18):12564-70.
PMID: 18292087

In this study, the researchers found that activating MC1R increases the levels of a protein called NR4A2 (or Nurr1). Nurr1 is a protein involved in the development and maintenance of dopamine producing neurons, and numerous recent studies have suggested that it is neuroprotective for these cells as well (Click here to read more on this).

So what does it all mean?

For some time there has been a curious link between people with red hair, melanoma and Parkinson’s disease. Now researchers in Boston have provided new evidence that the link exists, but they have also highlighted a new pathway via which novel therapies for Parkinson’s disease might be researched and developed.  Not a bad day at the office.


The banner for today’s post was sourced from Fancy mice

Phase II trial launched for Nilotinib

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Big news today from Georgetown University with the announcement that they will be starting a phase II trial for the cancer drug Nilotinib.

Click here to read the press release.

In this post we will discuss what has happened thus far and what the new trial will involve.


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Georgetown University (Washington DC). Source: Wallpapercave

In October 2015, researchers from Georgetown University announced the results of a small clinical trial at the Society for Neuroscience conference in Chicago.

It is no understatement to say that the results of that study got the Parkinson’s community very excited.

The study (see the abstract here) was a small clinical trial (12 subjects; 6 month study) that was aiming to determine the safety and efficacy of a cancer drug, Nilotinib (Tasigna® by Novartis), in advanced Parkinson’s Disease and Lewy body dementia patients. In addition to checking the safety of the drug, the researchers also tested cognition, motor skills and non-motor function in these patients and found 10 of the 12 patients reported meaningful clinical improvements.

In their presentation at the conference in Chicago, the investigators reported that one individual who had been confined to a wheelchair was able to walk again; while three others who could not talk before the study began were able to hold conversations. They suggested that participants who were still in the early stages of the disease responded best, as did those who had been diagnosed with Lewy body dementia.

The study involved the cancer drug Nilotinib.

What is Nilotinib?

Nilotinib (pronounced ‘nil-ot-in-ib’ and also known by its brand name Tasigna) is a small-molecule tyrosine kinase inhibitor, that has been approved for the treatment of imatinib-resistant chronic myelogenous leukemia (CML). That is to say, it is a drug that can be used to treat a type of leukemia when the other drugs have failed. It was approved for this treating cancer by the FDA in 2007.

How does Nilotinib work?

The researchers behind the study suggest that Nilotinib works by turning on autophagy – the “garbage disposal machinery” inside each neuron. Autophagy is a process that clears waste and toxic proteins from inside cells, preventing them from accumulating and possibly causing the death of the cell.

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The process of autophagy. Source: Wormbook

Waste material inside a cell is collected in membranes that form sacs (called vesicles). These vesicles then bind to another sac (called a lysosome) which contains enzymes that will breakdown and degrade the waste material.

The investigators believe that nilotinib may be helping in Parkinson’s disease, by clearing away the waste building up in cells – allowing the remaining cells to function more efficiently.

This is great, so what happened in 2016?

That’s a great question.

First, the results of the study being published (Click here to read those results). Second, the U.S. Food and Drug Administration (FDA) reviewed Georgetown’s investigational new drug application (IND) for nilotinib in Parkinson’s disease, and they informed the Georgetown University investigators that a new clinical trial could proceed.

But after that, there were whispers of issues and problems behind the scenes.

Back in August we wrote a post about the Phase II trial being delayed due to disagreements about the design of the study (Read that post by clicking here). Two separate research groups emerged from those disagreements (Georgetown University researchers themselves and a consortium including the Michael J Fox Foundation). Click here for the STAT website article outlining the background of the issues, and click here for the Michael J Fox Foundation statement regarding the situation. The Georgetown University team have a lot of leverage in this situation as they control the patent side of things (Click here to see the patent).

We are not sure what has happened since August, but the Georgetown University team has now announced that they are going to go ahead with a phase II trial to look at safety and efficacy of nilotinib in Parkinson’s disease.

What do we know about the new trial?

At the moment the details are basic:

The design of the study involves two parts:

In the first part of the study, one third of the participants receiving a low dose (150mg) of nilotinib, another third receiving a higher dose (300mg) of nilotinib and the final third will receive a placebo drug (a drug that has no bioactive effect to act as a control against the other two groups). The outcomes will be assessed clinically at six and 12 months by investigators who are blind to the treatment of each subject. These results will be compared to clinical assessments made at the start of the trial. (We are not sure if brain imaging – for example, a DATscan – will be included in the assessment, but it would be useful)

In the second part of the study, there will be a one-year open-label extension trial, in which all participants will be randomized given either the low dose (150mg) or high dose (300mg) of nilotinib. This extension is planned to start upon the completion of the first part (the placebo-controlled trial) to evaluate nilotinib’s long-term effects. (We are a little confused by this study design with regards to efficacy, but determining the safety issues of using nilotinib long term is important to establish).

We are not clear on how many subjects will be involved in the study or what the criteria for eligibility will be. All we can suggest is that if you are interested in finding out more about this new study, you can sign up here to receive more information as it becomes available.

 – – – – – – – – – – – – – –

Summing up, this is welcomed news for the Parkinson’s community as we will finally be able to determine if nilotinib is having positive effects in Parkinson’s disease. There have been some concerns raised that the effects of the drug in the first clinical study may have been the result of removing additional Parkinsonian treatments during the study (Click here for more on this). This new study will hopefully help to clarify things.

And fingers crossed provide us with a useful new treatment for Parkinson’s disease.


The banner for today’s post was sourced from William-Jon

New kiwi research in Parkinson’s disease

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I really didn’t expect to be writing about Parkinson’s research being conducted in New Zealand again so quickly, but yesterday a new study was published which has a few people excited.

It presents evidence of how the disease may be spreading… using cells collected from people with Parkinson’s disease.

In today’s post we will review the study and discuss what it means for Parkinson’s disease.


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The South Island of NZ from orbit. Source: Sciencenews

We may have mentioned the protein Alpha synuclein once or twice on this blog.

For anyone familiar with the biology of Parkinson’s disease, alpha synuclein is a major player. It is either public enermy no.1 in the underlying pathology of this condition or else it is the ultimate ‘fall guy’, left standing in the crime scene holding the bloody knife.

Remind me, what is alpha synuclein?

Alpha synuclein is an extremely abundant protein in our brains – making up about 1% of all the proteins floating around in each neuron (one of the main types of cell in the brain).

In healthy brain cells, normal alpha synuclein is typically found just inside the surface of the membrane surrounding the cell body and in the tips of the branches extending from the cell (in structures called presynaptic terminals which are critical to passing messages between neurons).

And why is alpha synuclein important in Parkinson’s disease?

Genetic mutations account for 10-20% of the cases in Parkinson’s disease.

Five mutations in the alpha-synuclein gene have been identified which are associated with increased risk of Parkinson’s disease (A53T, A30P, E46K, H50Q, and G51D – these are coordinates for locations on the alpha synuclein gene). Rare duplication or triplication of the gene have also been associated with  Parkinson’s disease.

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The structure of alpha synuclein protein – blue squares are mutations. Source: Mdpi

So genetically, alpha synuclein is associated with Parkinson’s disease. But it is also involved at the protein level.

In brains of many people with Parkinson’s disease, there are circular clumps of alpha synuclein (and other proteins) that collect inside cells. These clumps are called Lewy bodies. They are particularly abundant in areas of the brain that have suffered cell loss.

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A lewy body (brown with a black arrow) inside a cell. Source: Cure Dementia

No one has ever seen the process of Lewy body formation, so all we can do is speculate about how these aggregates develop. Currently there is a lot of evidence supporting the idea that alpha synuclein can be passed between cells. Once inside the new cell, the alpha synuclein helps to seed the formation of new Lewy bodies, and this is how the disease is believed to progress.

Mechanism of syunuclein propagation and fibrillization

The passing of alpha synuclein between brain cells. Source: Nature

Exactly how alpha synuclein is being passed between cells is the topic of much research at the moment. There are many theories and some results implicating methods such as direct penetration, or via a particular receptor. Perhaps even by a small package called an exosome being passed between cells (see image above).

How this occurs in the Parkinson’s disease brain, however, is unknown.

And this (almost) brings us to the kiwi scientists.

Last years, a group of Swiss scientists demonstrated that alpha synuclein could be passed between cells via ‘nanotubes’ – tiny tubes connecting between cells. The outlined their observations and results in this article:

switzerland
Title: Tunneling nanotubes spread fibrillar α-synuclein by intercellular trafficking of lysosomes.
Authors: Abounit S, Bousset L, Loria F, Zhu S, de Chaumont F, Pieri L, Olivo-Marin JC, Melki R, Zurzolo C.
Journal: EMBO J. 2016 Oct 4;35(19):2120-2138.
PMID: 27550960

The researchers who conducted this study were interested in tunneling nanotubes.

Yes, I know, ‘What are tunneling nanotubes?’

Tunneling nanotubes (also known as Membrane nanotubes or cytoneme are long protrusions extending from one cell membrane to another, allowing the two cells to share their contents. They can extend for long distances, sometimes over 100 μm – 0.1mm, but that’s a long way in the world of cells!

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Tunneling nanotubes (arrows). Source: Wikipedia (and PLOSONE)

Previous studies had demonstrated that tunneling nanotubes can pass different infectious agents (HIV for example – click here to read more on this), supporting the idea that these structures could be a general conduit by certain diseases could be spreading.

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A tunneling nanotube between two cells. Source: Pasteur

In their study the Swiss researchers found that alpha synuclein could be transferred between brain cells (grown in culture) via tunneling nanotubes. In addition, following that process of transfer, the alpha synuclein was able to induce the aggregation (or clumping) of the alpha synuclein in recipient cells.

A particularly interesting finding was that alpha synuclein appeared to encourage the appearance of tunneling nanotubes (there were more tunneling nanotubes apparent when cells produced more alpha synuclein). And the alpha synuclein that was being transferred was being passed on in ‘lysosomal vesicles’ – these are the rubbish bags of the cell (lysosomal vesicles are used to take proteins away for degradation).

Paints a rather insidious picture of the ‘ultimate fall guy’ huh!

And that image was made worse by the results published by the kiwis last night:

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Title: α-synuclein transfer through tunneling nanotubes occurs in SH-SY5Y cells and primary brain pericytes from Parkinson’s disease patients
Authors: Dieriks BV, Park TI, Fourie C, Faull RL, Dragunow M, Curtis MA.
Journal: Scientific Reports, 7, Article number: 42984
PMID: 28230073                    (This article is OPEN ACCESS if you would like to read it)

In their study, the New Zealand scientists extended the Swiss research by looking at cells collected from people with Parkinson’s disease. The researchers took human brain pericytes, which were derived from the postmortem brains of people who died with Parkinson’s disease.

And before you ask: pericytes are cells that wrap around the cells lining small blood vessels. They are important to the development of new blood vessels and maintaining the structural integrity of microvasculature.

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A pericyte (blue) hugging a blood vessel (red). Source: Xvivo

Pericytes contain alpha synuclein precipitates like those seen in neurons, and the kiwi scientists demonstrated that pericytes too can transfer alpha synuclein via tunneling nanotubes to neighbouring cells – representing a non-neuronal method of transport.

They also found that the transfer through the tunneling nanotubes can be very rapid – within 30 seconds – and the transferred alpha synuclein can hang around for more than 72 hours, suggesting that it is difficult for the receiving cell to dispose of. The researchers did note that the transfer through tunneling nanotubes occurred only in small subset of cells, but that this could explain the slow progression of Parkinson’s disease over time.

What does it all mean?

In order for us to truly tackle Parkinson’s disease and bring it under control, we need to know how this slowly progressing neurodegenerative condition is spreading. Some researchers in New Zealand have provided evidence involving cells collected from people with Parkinson’s disease that indicates one method by which the disease could be passed from one cell to another.

Tiny tunnels between cells, allowing material to be shared, could explain how the disease slowly progresses. The scientists observed the Parkinson’s associated protein alpha synuclein being passed between cells and then hanging around for more than a few days.

This method of transfer was made more interesting because the New Zealand researchers reported that non-neuronal cells (Pericytes, collected from people with Parkinson’s disease) could also form tunneling nanotubes. This observation raises questions as to what role non-neuronal cells could be playing in Parkinson’s disease.

This line of questions will obviously be followed up in future research, as will efforts to determine if tunneling nanotubes are actually present in the human brain or simply biological oddities present only in the culture dish. Demonstrating nanotubes in the brain will be difficult, but it would provide us with solid evidence that this method of disease transfer could be a bonafide cause of disease spread.

We watch with interest for further work in this area.


FULL DISCLOSURE: The author of this blog is a kiwi… and proud of it. He is familiar with the researchers who have conducted this research, but has had no communication with them regarding the publishing of this post. He simply thought that the results of their study would be of interest to the Parkinson’s community.


The banner for today’s post was sourced from Pinterest

How pigs are helping with Parkinson’s disease

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A biotech company in Australasia got the green light for the next round in a clinical trial two weeks ago.

Their product: tiny cylinders filled with pig cells.

Their mission: to treat Parkinson’s disease with the regenerative healing properties of naturally occurring cells.

In today’s post we will look at what the company is doing and what will happen next.


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Source: ProactiveInvestors

We have been contacted by several readers asking for a post on the press release last week regarding the clinical trial being conducted by Living Cell Technologies Limited (LCT).

Two weeks ago LCT received approval to commence the treatment of 6 patients in their third group of subjects in a Phase IIb clinical trial of NTCELL® for Parkinson’s disease, at Auckland City Hospital in New Zealand (Click here for the press release).

The company completed treatment of all six patients in ‘group 2’ of the Phase IIb clinical trial of NTCELL for Parkinson’s disease at the end of 2016. Four patients in the trial had 40 NTCELL microcapsules implanted into the putamen on each side of their brain, and two patients had sham surgery with no NTCELL implanted. They now have approval to repeat this in a third group of subjects.

What do we know about the company?

Founded in 1999, the initial goal of the company was to develop regenerative cell therapies. This goal was to be achieved by transplanting cells from Auckland Island pigs into humans.

The first disease considered for this approach was type 1 diabetes, which is now being pursued by a joint venture company in the US while LCT focuses its attention on Parkinson’s disease.

What are NTCELL microcapsules?

NTCELL is an a tiny capsule, that contains choroid plexus cells (taken from pigs). The capsule is made of a semi permeable membrane that allows all of the good chemicals and nutrients (that the cells are producing) to escape into the surrounding environment. At the same time it doesn’t let the cells escape, nor does it allow negative elements into the capsule. In addition, the bodies immune system can’t get at the foreign cells and remove them due to the membrane surrounding the capsule.

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An example of encapsulated cells. Source: LEN

These capsules can be transplanted into the brain of people with neurodegenerative conditions, providing the brains of those individuals with the benefits of supportive chemicals and nutrients.

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A brain scan of NTCELL capsules transplanted in the human brain. Source: LCT

Interesting, but what are choroid plexus cells?

Believe it or not, there are some empty spaces inside your brain. Spaces where there are no brain cells (neurons).

These spaces are called the ‘ventricles‘.

In the human brain there are 4 basic divisions of the ventricles as you can see in the image below (the ventricles are the yellow space):

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The ventricles and choroid Plexus in the human brain (red coloured regions). Source: PhysRev

The ventricles are filled up with a solution called cerebrospinal fluid. Cerebrospinal fluid is very similar to the liquid portion of blood (or plasma – if you remove the cells from blood, it’s called plasma), except that cerebrospinal fluid is nearly devoid of protein. It is actually made from plasma, but it only contains 0.3% of plasma proteins and about 2/3 of the glucose of blood.

The choroid plexus cells are one of the primary sources of production for the cerebrospinal fluid. That production is actually great – total volume of cerebrospinal fluid in the the average human being turns over almost 4 times per day. Choroid plexus cells can be found in all 4 divisions of the ventricular system (the choroid plexus cells are indicated with red/brown colouring in the image above).

And, um… why pigs?

The choroid plexus cells are sourced from a unique herd of pigs that have been designated pathogen-free. They were originally sourced from the remote sub-Antarctic Auckland Islands, where they have been running around in isolation since 1807.

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The not-so-tropical Auckland Islands, south of NZ. Source: Sciblogs

That isolation has made them ‘pathogen free’ – basically there is a reduced likelihood of endogenous infectious agents (eg. porine (pig) retrovirus (or PERVs)) in the cells – which is a good thing when you are planning to stick something in the brain.

What research has been done on NTCELL?

Firstly, regarding the capsules, the company published this report in 2009:

capsules

Title: Encapsulated living choroid plexus cells: potential long-term treatments for central nervous system disease and trauma.
Authors: Skinner SJ, Geaney MS, Lin H, Muzina M, Anal AK, Elliott RB, Tan PL.
Journal: J Neural Eng. 2009 Dec;6(6):065001.
PMID: 19850973

In this study, the company looked at the utility of the capsules in rodent brains. One important aspect that they wanted to address was how well the cells survive inside the capsules when placed in the brain. They found that the capsules effectively protected the cells from the host immune system, and they survived for the length of the 6 months study without causing any adverse effects.

The capsules were retrieved from the brains of the rats at the end of the study and the viability of cells was analysed. The researchers found that there was no difference in the production of nutrients from the cells in the capsules at 4 months post implantation, but they did see a decrease of 33% at 6 months. In addition, the number of cells decreased to approximately 40% of the pre-implantation values at 6 months.

We are unsure whether the capsules have been altered for the clinical trial.

The researchers followed this research up in 2013 by publishing this paper:

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Title: Recovery of neurological functions in non-human primate model of Parkinson’s disease bytransplantation of encapsulated neonatal porcine choroid plexus cells.
Authors: Luo XM, Lin H, Wang W, Geaney MS, Law L, Wynyard S, Shaikh SB, Waldvogel H, Faull RL, Elliott RB, Skinner SJ, Lee JE, Tan PL.
Journal: J Parkinsons Dis. 2013 Jan 1;3(3):275-91. doi: 10.3233/JPD-130214.
PMID: 24002224       (This article is OPEN ACCESS if you would like to read it)

The researchers wanted to test the capsules in non-human pre-clinical trials. For this purpose they induced Parkinson’s disease in 15 monkeys using the neurotoxin MPTP, waited 10 weeks and then implanted their capsules. Six monkeys were implanted with the NTCELL capsules, 6 were implanted with empty capsules, and 3 received no capsules. The animals were then tested out to 24 weeks post implantation.

The behavioural response was dramatic. Most of the primates with the NTCELL capsules demonstrated positive behavioural benefits by 2 weeks post implantation (becoming statistically significant by 4 weeks), while the controls and empty capsule groups exhibited no behavioural recovery at all across the entire 24 weeks.

In addition to behavioural benefits, the investigators found significantly more dopamine neurons in the brains of the monkeys implanted with the NTCELL capsules when compared to the controls.

These findings were used by the company to justify moving towards clinical trials in humans.

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Source: Healthline

And what do we know about the clinical trial for Parkinson’s disease?

A Phase I/IIa NTCELL clinical trial for the treatment of Parkinson’s disease was completed in June 2015. It was an open label investigation of the safety and clinical effect of NTCELL in 4 people who had been diagnosed with Parkinson’s disease for at least five years.

The trial “met the primary endpoint of safety” and “reversed progression of the disease two years after implant” (as measured by the Unified Parkinson’s Disease Rating Scale (UPDRS)). The NTCELL implantation was well tolerated, with “no adverse events considered to be related to NTCELL”. The results of the trial have not been published, but the press release can be found here.

The results from that trial were used to justify and design a larger Phase IIb trial.

What does Phase IIb mean?

Phase II studies, which are designed to address clinical efficacy and biological activity, can be divided into IIA or IIB, and while there is no stated definition for these labels it is generally agreed that:

  • Phase IIA studies are usually pilot studies designed to demonstrate clinical efficacy or biological activity (‘proof of concept’ studies);
  • Phase IIB studies look to find the optimum dose at which the drug shows biological activity with minimal side-effects (‘definite dose-finding’ studies) – (Source: Wikipedia).

The goal of this Phase IIb LCT clinical study is to “confirm the most effective dose of NTCELL, define any placebo component of the response and further identify the initial target Parkinson’s disease patient sub group”.

A total of 18 patients under 65 years old are taking part in the trial being conducted at Auckland Hospital and Mercy Ascot Hospital in New Zealand. The company will have to wait 26 weeks until after the last patient is implanted to know whether it has been successful in meeting regulator’s conditions on quality, safety, and efficacy. At the 26 weeks mark, the subjects that received the placebo (empty capsules) will be given the NTCELL capsules.

If the current Phase IIb trial is successful, Living Cell Technologies Limited will be looking to “apply for provisional consent to treat paying patients in New Zealand and launch NTCELL® as the first disease modifying treatment for Parkinson’s disease, in 2017” (Source: Ltcglobal). We will wait to see the results of the current study before passing judgement on whether this situation is likely, though it does seem premature given that by the end of the phase IIb trial only 20 people with Parkinson’s disease will have received the NTCELL treatment. A larger phase III trial may be required. Alternatively, if the results of the current trial are truly spectacular, the company may be able to propose a Phase IV style of trial (also called a ‘post-marketing surveillance’ trial) which would allow them to market their product, but they would be required to maintain a strict program of safety surveillance and ongoing technical analysis of the treatment.

Are other companies trying to do something similar?

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Source: NSgene

Another company, NSgene (in Denmark) has a similar sort of experimental product called NsG0301 which is encapsulated human cells that express the neuroprotective protein, GDNF. NsG0301 is still in preclinical testing however, with the Michael J Fox Foundation helping the company to get the clinical trials started.

Sounds very interesting, but what does it all mean?

So in summary, the biotech company LCT have been given permission to continue with their phase II clinical trial which involves placing tiny capsules which contain cells that release beneficial nutrients into the brains of people with Parkinson’s disease. The company will be blind to which individuals are receiving the capsules with cells in them or empty capsules. They should know later in the year if the trials is successful.

One positive feature of this idea is that immune-suppressant treatments are not required as they are with other forms of transplantation therapies. This means that the patient doesn’t need to take medication which stops the immune system from attacking the foreign cells, because the cells are protected by the capsule membrane. Such medication can leave subjects with reduced immune system responses to illness and thus vulnerable.

Having said that, we are a little concerned that the NTCELL product has not been tested thoroughly enough in Parkinson’s disease for the company to be proposing it for commercial use later this year. For example, the phase I open label results could easily be the result of the placebo effect in practise (as all 4 participants knew they were receiving the capsules. This issue could be resolved with DATscan brain imaging of the first 4 subjects (in the phase I trial).

In addition, we would be interested to know how long the cells inside the capsules keep producing cerebrospinal fluid and other beneficial nutrients once inside the human brain. The rodent study (reviewed above) suggested reductions in production from the cells after just 6 months.

While the NTCELL capsules have been tested in many different models of neurological conditions (see the LCT’s publication page for more on this), the company suffered a set back in 2014 when they retracted one of their key pieces of research which demonstrated the use of NTCELL in a rodent model of Parkinson’s disease (Click here for more on this). The study in question was conducted by LCT between 2007 – 2009, and the results were published in The Journal of Regenerative Medicine in 2011. The study was retracted, however, because “the efficacy conclusions in the publication cannot be confirmed”.

To be fair, the company requested the retraction themselves – which is to their credit – and as a precautionary measure LCT placed a hold on any further patient recruitment in their Phase I/IIa clinical study that was underway at the time. But with this study retracted, the published preclinical research for NTCELL in Parkinson’s disease is largely limited to the primate study reviewed above (we are happy to be corrected on this).

We will be intrigued to see the results of the phase II trial, and (if all goes well) whether the New Zealand regulators will be happy for the product to be made commercially available. Depending on the results, they may request further studies. It will definitely be interesting to follow up long-term the 20 subjects who will have received the NTCELL product by that time.

We watch and wait.


FULL DISCLOSURE: Living Cell Technologies Limited (LCT) is an Australasian biotechnology company that is publicly listed on the ASX and NSgene is a privately owned company. Under no circumstances should investment decisions be made based on the information provided here. In addition, SoPD has no financial or beneficial connection to either company. We have not been approached/contacted by either company to produce this post. We are simply presenting this information here following requests from our readers and because we thought the science of what the company is doing might be of interest to other readers. The author of this blog is associated with an individual contracted by LCT, but that individual did not request nor was not made aware of this post before publication. 


The banner for today’s post was sourced from the Planner

Confirmation about that gut feeling?

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Very interesting results published last week regarding the bacteria in the intestinal system of people with Parkinson’s disease.

This is an important piece of research because the gut is increasingly being seen as one of the potential start sites for Parkinson’s disease.

In today’s post we will review the results and discuss what they mean.


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Bacteria in the gut. Source: Huffington Post

Before you go to bed tonight, contemplate this:

The human gut hosts tens of trillions of microorganisms, including at least 1000 species of bacteria (which is a guess-timate as we are not really sure how many species there are).

And whenever you feel like you are all alone, know that you are not.

You are never alone: tens of trillions of microorganisms are with you!

And there is sooooooo many of these microorganisms, that they can make up as much as 2 kg of your total weight.

What do the microorganisms do?

Ours bodies are made up of microbiota – that is,  collections of microbes or microorganisms inhabiting particular environments (or region of our body) and creating “mini-ecosystems”. And whether you like this idea or not, you need them.

The microorganisms in the human gut, for example, perform all manner of tasks for you to make your life easier. From helping to break down food, to aiding with the production of some vitamins (in particular B and K).

That’s great, but what does the bacteria in our gut have to do with Parkinson’s disease?

People with Parkinson’s disease quite often have issues associated with the gastrointestinal tract (or the gut), such as constipation for example. Some people believe that some of these gut related symptoms may actually pre-date a diagnosis of Parkinson’s disease, which has led many researchers to speculate as to whether the gut could be a starting point for the condition.

We have previously discussed the gut and Parkinson’s disease in several posts (click here, here and here to read them).

Today we re-address this topic because a group of scientists from the USA have determined that the populations of bacteria in the guts of people with Parkinson’s disease are different to those of healthy individuals.

Sounds interesting. What exactly is the difference?

Well, before we discuss that, we need a little bit of background.

In 2015, a group of scientists from Finland, published this research paper:

biota-title

Title: Gut microbiota are related to Parkinson’s disease and clinical phenotype.
Authors: Scheperjans F, Aho V, Pereira PA, Koskinen K, Paulin L, Pekkonen E, Haapaniemi E, Kaakkola S, Eerola-Rautio J, Pohja M, Kinnunen E, Murros K, Auvinen P.
Journal: Mov Disord. 2015 Mar;30(3):350-8.
PMID: 25476529

In this study the researchers compared the fecal microbiomes of 72 people with Parkinson’s disease and 72 control subjects by sequencing the V1-V3 regions of the bacterial 16S ribosomal RNA gene.

Hang on a minute. What does… any of that mean?

Yeah. Ok, that was a bit technical.

The microbiome refers to the genetics of the microorganisms – that is their genomes (or DNA). When researchers want to look at the microbiome of your gut, they do so by collecting fecal samples (delightful job, huh?).

Interesting facts: Fresh feces is made up of approx. 75% water. Of the remaining solid fraction, 84–93% is organic solids. These organic solids consist of: 25–55% gut bacterial matter, 2–25% protein, 25% carbohydrates, and 2–15% fat (Source: Wikipedia).

Still with me?

After collecting the fecal samples, researchers will extract the DNA from the gut bacterial material, which they can then analyse.

And what are the V1-V3 regions of the bacterial 16S ribosomal RNA gene?

The 16S ribosomal RNA gene is universal in bacteria – it is present in all of their genomes/DNA. The genetic sequence of this particular gene is approximately 1,550 base pairs long, and contains regions that are highly conserved (that is they are shared between species) and highly variable (very different between species).

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The 16S ribosomal RNA gene. Source: Alimetrics

The gene contains nine of these highly variable regions (called V1 – V9) that display considerable differences in the genetic sequence between different groupings of bacteria. The V2 and V3 regions are considered the most suitable for distinguishing all bacterial species to the genus level (‘genus‘ being a method of classification).

Now scientist can amplify the 16S ribosomal RNA gene by making lots of copies of the highly conserved regions (using PCR) which are shared between bacteria, but then they will genetic sequence the variable sections in between (in this case V2 & V3), which will allow them to discriminate and quantify the different species of microorganisms (such as bacteria) within a particular sample.

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16S rRNA gene analysis – looks complicated. Source: Slideshare

And this is what the scientists in this study did.

They took fecal samples of 72 people with Parkinson’s disease and 72 control subjects, amplified the V1-V3 regions of the bacterial 16S ribosomal RNA gene, and then sequenced the variables regions in between to determine what sorts of bacteria were present (and/or different) in the guts of people with Parkinson’s disease.

The researchers found that there was a reduced abundance of Prevotellaceae in the guts of people with Parkinson’s disease (Prevotellaceae are commonly found in the gastric system of people who maintain a diet low in animal fats and high in carbohydrates, for example vegetarians).

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Prevotella multisaccharivorax which belongs to the Prevotellaceae family. Source: MindsofMalady

In addition, the investigators also reported a positive association between the abundance of Enterobacteriaceae and postural instability and gait difficulty symptoms – that is to say, people with Parkinson’s disease who also had postural instability and gait difficulties had significantly more Enterobacteriaceae in their guts than people with Parkinson’s disease who were more tremor dominant.

Due to the design of the study, the researchers were not able to make conclusions about causality from their study. Neither could they tell whether the microbiome changes were present before the onset of Parkinson’s disease or whether they simply developed afterwards. All they could really say was at the time of analysis, they did see a difference in the gut microbiota between people with and without Parkinson’s disease.

And while these same researchers are currently conducting a two year follow up study to determine the stability of these differences over time in the same subjects, they admit that much larger prospective studies are required to address such issues as causality.

Which brings us to the new research published last week:

gut-title

Title: Parkinson’s disease and Parkinson’s disease medications have distinct signatures of the gut microbiome.
Authors: Hill-Burns EM, Debelius JW, Morton JT, Wissemann WT, Lewis MR, Wallen ZD, Peddada SD, Factor SA, Molho E, Zabetian CP, Knight R, Payami H.
Journal: Mov Disord. 2017 Feb 14. [Epub ahead of print]
PMID: 28195358

The researchers in this study (completely independent from the previous study) applied the same study design as the previous study, but on a much larger scale:

They took samples from a total of 197 people with Parkinson’s disease and 130 healthy controls. And importantly, none of the individual subjects in the study were related (this was an attempt to reduce the effect of shared microbiota between people who live together). Participants were enrolled from the NeuroGenetics Research Consortium in the cities of Seattle (Washington), Atlanta (Georgia) and Albany (New York).

So what did they find?

The researcher’s data revealed alterations in at least 7 families of bacteria: Bifidobacteriaceae, Christensenellaceae, Tissierellaceae, Lachnospiraceae, Lactobacillaceae, Pasteurellaceae, and Verrucomicrobiaceae families

Of particular interest was their observation of reduced levels of Lachnospiraceae in Parkinson’s disease subjects. Lachnospiraceae is involved with the production of short chain fatty acids (SCFA) in the gut. Depletion of SCFA has been implicated in the pathogenesis of Parkinson’s disease (Click here for more on this), and it could potentially explain the inflammation and microglial cell activation observed in the brain (Click here for more on this).

Importantly, they did not replicate the association of Parkinson’s disease with Prevotellaceae (see the previous study above).

The investigators also looked at the medication that the subjects were taking and they found a significant difference in the gut microbiome in relation to treatment with COMT inhibitors and anticholinergics. The effects of COMT inhibitors and anticholinergics on hte microbiome was independent of the effect that Parkinson’s disease was having.

The investigators concluded that Parkinson’s disease is accompanied by ‘dysbiosis of gut microbiome’ (that is, microbial imbalance). Again they could not determine whether the ‘chicken came before the egg’ so to speak, but it will be interesting to see what follow up work in this study highlights.

What does it all mean?

The studies that we have reviewed today provide us with evidence that the bacteria in the guts of people with Parkinson’s disease are different to that of healthy control subjects. Whether the differences between the studies results are due to regional effects (Finland vs USA) will require further investigation. But given that so much attention is now focused on the role of the gut in Parkinson’s disease, it is interesting that there are differences in the gut microbiome between people with and without Parkinson’s disease.

One issue that both studies do not address is whether this difference is specific to Parkinson’s disease and not other neurodegenerative conditions. That is to say, it would have been very interesting if the investigators had included a small set of samples from people with Alzheimer’s disease, for example. This would indicate which differences are specific to Parkinson’s disease as opposed to differences that a general to individuals who have a neurodegenerative condition. If they can tease out medication-related differences (in the second study), then this should be a do-able addition to any future studies.

One would also hope that the researchers will go back and dig a little deeper with future analyses. Using 16S ribosomal RNA gene analysis to determine and quantify the different families of bacteria is analogous to dividing people according to hair and eye colour. The bacteria of our gut is a lot more complicated than this review has suggested. For example, future studies and follow up research could include some genetic techniques that go beyond simply sequencing the 16S ribosomal RNA gene. The investigators could sequence the entire genomes of these species of bacteria to see if genetic mutations within a particular family of bacteria is present in people with Parkinson’s disease.

Easy to say of course. A lot of work, in practise.

There is most likely going to be more of a focus on the gastrointestinal tract in Parkinson’s disease research as a result of these studies. It will be interesting to see where this research leads.


The banner for today’s post was sourced from Youtube

Pink flies in Leicester at it again

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Imagine discovering a protein that could make the power supply of your cells healthier AND perhaps provide a new therapeutic target for Parkinson’s disease.

That would be a pretty big deal right?

Well, this week, researchers may have found just such a protein. In today’s post we will review their finding and discuss what it means for Parkinson’s disease.


This is Dr Miguel Martins:

miguel_martins

Source: Tox.mrc.ac.uk

He’s a dude.

Dr Martins is a group leader at the MRC toxicology unit in Leicester – a city in the East Midlands of England.

leicester-town-hall-squareLeicester. Source: Keithvazmp

You may have heard of Leicester. Last year their football team had a dream season, miraculously winning the Premier league title despite starting with odds of 5000:1.

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Last season’s winners. Source: Goal.com

This season, however,….well, uh…

Let’s move on, shall we.

Recently we reviewed Dr Martins research group’s work on ‘Pink flies’ and how they survive longer on Niacin rich diets (Click here for that post). He and his group were again publishing research this week, involving new a new study highlighting a protein that may help with keeping mitochondria healthy.

What are mitochondria?

Good question.

Mitochondria are the power house of each cell. They keep the lights on. Without them, the lights go out and the cell dies.

Mitochondria

Mitochondria and their location in the cell. Source: NCBI

You may remember from high school biology class that mitochondria are bean-shaped objects within the cell. They convert energy from food into Adenosine Triphosphate (or ATP). ATP is the fuel which cells run on. Given their critical role in energy supply, mitochondria are plentiful and highly organised within the cell, being moved around to wherever they are needed.

So what has Dr Martins group found?

This week they published this study:

atf4

Title: dATF4 regulation of mitochondrial folate-mediated one-carbon metabolism is neuroprotective.
Authors: Celardo I, Lehmann S, Costa AC, Loh SH, Miguel Martins L.
Journal: Cell Death Differ. 2017 Feb 17. [Epub ahead of print]
PMID: 28211874       (This article is OPEN ACCESS if you would like to read it)

In the study, the researchers were interested in determining what changes occur in the flies that are missing the Parkinson’s disease associated genes PINK1 or PARKIN, particularly which transcription factors are affected.

What is a transcription factor?

Another good question.

Ok, so you remember your high school science class when the adult at the front of the class was explaining biology 101? And they were saying that DNA gives rise to RNA, RNA gives rise to protein? The central dogma of biology. Remember this?

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The basic of biology. Source: Youtube

Ultimately this DNA-RNA-Protein mechanism is a circular cycle, because the protein that is produced using RNA is required at all levels of this process. Some of the protein is required for making RNA from DNA, while other proteins are required for making protein from the RNA instructions.

A transcription factor is a protein that is involved in the process of converting (or transcribing) DNA into RNA.

Importantly, a transcription factor can be an ‘activator’ of transcription – that is initiating or helping the process of generating RNA from DNA.

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An example of a transcriptional activator. Source: Khan Academy

Or it can be a repressor of transcription – blocking the machinery (required for generating RNA) from doing it’s work.

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An example of a transcriptional repressor. Source: Khan Academy

In their study, Dr Martins and colleagues were looking for changes in the levels of proteins that either initiate or repress transcription, as these are the proteins that are ultimately at the start of the process of making things happen.

And what do Parkin and Pink1 actually do?

About 10% of cases of Parkinson’s disease can be attributed to genetic mutations in particular genes. PINK1 and PARKIN are two of those genes.

People with particular mutations in the PINK1 or PARKIN gene are vulnerable to developing an early onset form of Parkinson’s disease.

As to what the protein that is generated from PINK1 or PARKIN DNA & RNA, well in normal, healthy cells, the PINK1 protein is absorbed by mitochondria and eventually degraded. In unhealthy cells, however, this process is inhibited and PINK1 starts to accumulate on the outer surface of the mitochondria. There, it starts grabbing the PARKIN protein. This pairing is a signal to the cell that this particular mitochondria is not healthy and needs to be removed.

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Pink1 and Parkin in normal (right) and unhealthy (left) situations. Source: Hindawi

The process by which mitochondria are removed is called autophagy. Autophagy is an absolutely essential function in a cell. Without it, old proteins will pile up making the cell sick and eventually it dies. Through the process of autophagy, the cell can break down the old protein, clearing the way for fresh new proteins to do their job.

Think of autophagy as the waste disposal process of the cell.

In the absence of PINK1 and PARKIN – as is the case in some people with Parkinson’s disease who have genetic mutations in these genes – we believe that sick/damaged mitochondria start to pile up and are not disposed of appropriately. This results in the cell dying.

Ok, so the researchers were looking for transcription factors that change in the absence of PINK1 and PARKIN. How did they do this experiment?

They used flies.

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PINK flies. Source: Wallpapersinhq

The researchers took the heads (yes, I know, delightful stuff) of ‘young’ 3-day-old Pink1 and Parkin mutant flies and compared them to ‘aged’ heads from 21- and 30-day-old Parkin and Pink1 mutant flies, respectively. The comparison was specifically looking at transcription factors that change over time.

This analysis revealed a protein called activating transcription factor 4 (or ATF4).

The researchers found that ATF4 levels were higher in both Pink1 and Parkin mutants than levels in control flies. Importantly, the researchers next looked at the genes that this transcription factor (ATF4) was regulating, and they found that ATF4 was encouraging the production of proteins that protect mitochondria. The researchers noticed that when they reduced ATF4 in flies, the levels of these critical mitochondrial proteins dropped as well.

When the researchers reduced the levels of each of these critical mitochondrial proteins in flies, it resulted in impaired climbing ability (suggesting a locomotor deficit) and decreased lifespan. Interestingly, these protective mitochondrial proteins are increased in the Pink1 and Parkin flies, suggesting that efforts to keep the mitochondria healthy are active inside the cells.

Finally, the researchers increased the levels of these protective mitochondrial proteins in the Pink1 and Parkin mutants and they found that the mitochondrial function was improved, and neuronal cell loss was avoided. They concluded that their findings demonstrate a central role for ATF4 signalling in Parkinson’s disease and that this protein may represent a target for new therapeutic strategy.

So what does it all mean?

The researchers behind this study were looking for biological pathways that are altered in genetic forms of Parkinson’s disease and they have identified a protein that is involved with keeping mitochondria healthy. This pathway could represent a new therapeutic target for future treatments, and also opens a new door in our understanding of Parkinson’s disease.

ATF4 is currently not directly targeted by any medications (that we are aware of), but there are drugs in clinical trials that target proteins that subsequently activate ATF4. For example, Oncoceutics Inc. have a drug candidate called ONC201 (currently in phase II trials for brain cancer) which kills solid tumor cells by triggering an stress response which is dependent on ATF4 activation.

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Source: Oncoceutics Inc

We are not for a second suggesting that this is a viable drug for Parkinson’s disease (so PLEASE DON’T rush out and besiege the company for all of their stocks!) – ATF4 should be considered a very experimental target until these results are replicated by independent research groups. We are mentioning ONC201 here simply to indicate that there is a field of research surrounding this potential target (ATF4) and it may be worthwhile for the Parkinson’s community to follow up this line of investigation.

We are assuming that while Leicester football club is struggling, the Martins lab are currently investigating compounds that activate ATF4 (and the other critical mitochondrial proteins), and we will report any follow up work as it comes to hand.

Watch this space.


And if nothing we’ve written here makes any sense, the good folks at Leicester University have kindly provided a short video explaining the research:


Postscript (March 2017):

matters_journal

The Martins lab have done it again!

This time in the OPEN ACCESS online journal Science Matters, they have published this article:

Matters

Title: Folinic acid is neuroprotective in a fly model of Parkinson’s disease associated with pink1 mutations
Authors: Lehmann S , Jardine J, Garrido – Maraver J, Loh SH, & Martins LM
Journal: Science Matters

In this study, the researchers demonstrated that a folinic acid-enriched diet might delay or prevent the neuronal loss in people with PINK1 associated Parkinson’s disease. They present data suggesting that beginning an intake of Folinic acid in early to middle stages of adulthood prevents the degeneration of dopamine neurons in pink1 mutant flies.

Folinic acid (also known as leucovorin) is a medication used to decrease the toxic effects of chemotherapy drugs. The pharmacokinetics of leucovorin suggests that it readily crosses the blood-brain-barrier (Source), so it would be possible for a clinical trial to be set up in human. Before taking that path, however, more testing is required (ideally in a mammalian model of Parkinson’s disease).

Amazing that all these results are coming from silly old flies though, huh?


The banner for today’s post was sourced from Tox.mrc.ac.uk