Tagged: GBA

Non-invasive gene therapy: “You never monkey with the truth”

Gene therapy involves treating medical conditions at the level of DNA – that is, altering or enhancing the genetic code inside cells to provide therapeutic benefits rather than simply administering drugs. Usually this approach utilises specially engineered viruses to deliver the new DNA to particular cells in the body.

For Parkinson’s, gene therapy techniques have all involved direct injections of these engineered viruses into the brain – a procedure that requires brain surgery. This year, however, we have seen the EXTREMELY rapid development of a non-invasive approach to gene therapy for neurological condition, which could ultimately see viruses being injected in the arm and then travelling up to the brain where they will infect just the desired population of cells.

Last week, however, this approach hit a rather significant obstacle.

In today’s post, we will have a look at this gene therapy technology and review the new research that may slow down efforts to use this approach to help to cure Parkinson’s.


Gene therapy. Source: rdmag

When you get sick, the usual solution is to visit your doctor.

They will prescribe a medication for you to take, and then all things going well (fingers crossed/knock on wood) you will start to feel better. It is a rather simple and straight forward process, and it has largely worked well for most of us for quite some time.

As the overall population has started to live longer, however, we have begun to see more and more chronic conditions which require long-term treatment regimes. The “long-term” aspect of this means that some people are regularly taking medication as part of their daily lives. In many cases, these medications are taken multiple times per day.

A good example of this is Levodopa (also known as Sinemet or Madopar) which is the most common treatment for the chronic condition of Parkinson’s disease.

When you swallow your Levodopa pill, it is broken down in the gut, absorbed through the wall of the intestines, transported to the brain via our blood system, where it is converted into the chemical dopamine – the chemical that is lost in Parkinson’s disease. This conversion of Levodopa increases the levels of dopamine in your brain, which helps to alleviate the motor issues associated with Parkinson’s disease.

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Levodopa. Source: Drugs

This pill form of treating a disease is only a temporary solution though. People with Parkinson’s – like other chronic conditions – need to take multiple tablets of Levodopa every day to keep their motor features under control. And long term this approach can result in other complications, such as Levodopa-induced dyskinesias in the case of Parkinson’s.

Yeah, but is there a better approach?

Continue reading

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AAV-PHP.B: The future is apparently now

In addition to looking at current Parkinson’s disease research on this website, I like to look at where technological advances are taking us with regards to future therapies.

In July of this year, I wrote about a new class of engineered viruses that could potentially allow us to treat conditions like Parkinson’s disease using a non-invasive, gene therapy approach (Click here to read that post). At the time I considered this technology way off at some point in the distant future. Blue sky research. “Let’s wait and see” – sort of thing.

So imagine my surprise when an Italian research group last weekend published a new research report in which they used this futurist technology to correct a mouse model of Parkinson’s disease. Suddenly the distant future is feeling not so ‘distant’.

In today’s post we will review and discuss the results, and look at what happens next.


Technological progress – looking inside the brain. Source: Digitial Trends

I have said several times in the past that the pace of Parkinson’s disease research at the moment is overwhelming.

So much is happening so quickly that it is quite simply difficult to keep up. Not just here on the blog, but also with regards to the ever increasing number of research articles in the “need to read” pile on my desk. It’s mad. It’s crazy. Just as I manage to digest something new from one area of research, two or three other publications pop up in different areas.

But it is the shear speed with which things are moving now in the field of Parkinson’s research that is really mind boggling!

Source: Pinterest

Take for example the case of Squalamine.

In February of this year, researchers published an article outlining how a drug derived from the spiny dogfish could completely suppress the toxic effect of the Parkinson’s associated protein Alpha Synuclein (Click here to read that post).

The humble dogfish. Source: Discovery

And then in May (JUST 3 MONTHS LATER!!!), a biotech company called Enterin Inc. announced that they had just enrolled their first patient in the RASMET study: a Phase 1/2a randomised, controlled, multi-center clinical study evaluating a synthetic version of squalamine (called MSI-1436) in people with Parkinson’s disease. The study will enrol 50 patients over a 9-to-12-month period (Click here for the press release).

Source: Onemednews

Wow! That is fast.

Yeah, I thought so too, but then this last weekend a group in Italy published new research that completely changed my ideas on the meaning of the word ‘fast’. Regular readers will recall that in July I discussed amazing new technology that may one day allow us to inject a virus into a person’s arm and then that virus will make it’s way up to the brain and only infect the cells that we want to have a treatment delivered to. This represents non-invasive (as no surgery is required), gene therapy (correcting a medical condition with the delivery of DNA rather than medication). This new study used the same virus we discussed in July.

Continue reading

O’mice an’ men – gang aft agley

This week a group of scientists have published an article which indicates differences between mice and human beings, calling into question the use of these mice in Parkinson’s disease research.

The results could explain way mice do not get Parkinson’s disease, and they may also partly explain why humans do.

In today’s post we will outline the new research, discuss the results, and look at whether Levodopa treatment may (or may not) be a problem.


The humble lab mouse. Source: PBS

Much of our understanding of modern biology is derived from the “lower organisms”.

From yeast to snails (there is a post coming shortly on a snail model of Parkinson’s disease – I kid you not) and from flies to mice, a great deal of what we know about basic biology comes from experimentation on these creatures. So much in fact that many of our current ideas about neurodegenerative diseases result from modelling those conditions in these creatures.

Now say what you like about the ethics and morality of this approach, these organisms have been useful until now. And I say ‘until now’ because an interesting research report was released this week which may call into question much of the knowledge we have from the modelling of Parkinson’s disease is these creatures.

You see, here’s the thing: Flies don’t naturally develop Parkinson’s disease.

Nor do mice. Or snails.

Or yeast for that matter.

So we are forcing a very un-natural state upon the biology of these creatures and then studying the response/effect. Which could be giving us strange results that don’t necessarily apply to human beings. And this may explain our long history of failed clinical trials.

We work with the best tools we have, but it those tools are flawed…

What did the new research report find?

This is the study:


Title: Dopamine oxidation mediates mitochondrial and lysosomal dysfunction in Parkinson’s disease
Authors: Burbulla LF, Song P, Mazzulli JR, Zampese E, Wong YC, Jeon S, Santos DP, Blanz J, Obermaier CD, Strojny C, Savas JN, Kiskinis E, Zhuang X, Krüger R, Surmeier DJ, Krainc D
Journal: Science, 07 Sept 2017 – Early online publication
PMID: 28882997

The researchers who conducted this study began by growing dopamine neurons – a type of cell badly affected by Parkinson’s disease – from induced pluripotent stem (IPS) cells.

What are induced pluripotent stem cells?

Continue reading

An Ambroxol update – active in the brain

Ambroxol-800x400

This week pre-clinical data was published demonstrating that the Ambroxol is active in the brain.

This is important data given that there is currently a clinical trial being conducted for Ambroxol in Parkinson’s disease.

Today’s post will review the new data and discuss what is happening regarding the clinical trial.


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Ambroxol. Source: Skinflint

We have previously discussed the potential use of Ambroxol in the treatment of Parkinson’s disease (Click here to read that post). Today we follow up that post with new data that provides further support for an on-going clinical trial.

Firstly, what is Ambroxol?

Ambroxol is a commonly used treatment for respiratory diseases (the respiratory system being the lungs and related components required for breathing). Ambroxol promotes the clearance of mucus and eases coughing. It also has anti-inflammatory properties, reducing redness in a sore throat. It is the active ingredient of products like Mucosolvan, Mucobrox, and Mucol.

 

What is the connection between Ambroxol and Parkinson’s disease?

So this is where a gene called GBA comes into the picture.

Genetic mutations in the GBA (full name: Glucosylceramidase Beta) gene are the most common genetic anomaly associated with Parkinson’s disease. People with a mutation in their GBA gene have a higher risk of developing Parkinson’s disease than the general population. And interestingly, people with Parkinson’s disease are approximately five times more likely to carry a GBA mutation than healthy control subjects.

What does GBA do?

The GBA gene provides the instructions for making an enzyme (called glucocerebrosidase) that helps with the digestion and recycling of waste inside cells. The enzyme is located and active inside ‘lysosomes‘.

What are Lysosomes?

Lysosomes are small bags of digestive enzymes that can be found inside cells. They help to break down proteins that have either been brought into the cell or that have served their function and need to be digested and disposed of (or recycled).

Lysosomes

How lysosomes work. Source: Prezi

Inside the lysosomes are enzymes like glucocerebrosidase which help to break material down into useful parts. The lysosome will fuse with other small bags (called vacuole) that act as storage vessels of material inside a cell. The enzymes from the lysosome will mix with the material in the vacuole and digest it (or it break down into more manageable components).

Now people with a genetic mutation in their GBA gene will often have an abnormally short, non-functioning version of the glucocerebrosidase enzyme. In those cases the breaking down of waste inside the lysosome becomes inhibited. And if waste can’t be disposed of or recycled properly, things start to go wrong in the cell.

How does Ambroxol correct this?

It was recently shown that Ambroxol triggers exocytosis of lysosomes (Source). Exocytosis is the process by which waste is exported out of the cell.

exocytosis

Exocytosis. Source: Socratic

Thus by encouraging lysosomes to undergo exocytosis and spit their contents out of the cell – digested or not – Ambroxol allows the cell to remove waste effectively and therefore function in a more normal fashion. This mechanism of treatment seemingly bi-passes the faulty glucocerebrosidase digestion enzyme entirely.

Until recently, two important questions, however, have remained unanswered:

  1. Does Ambroxol enter the brain and have this function there?
  2. What are the consequences of long term Ambroxol use?

We now have an answer for question no. 1:

Amb2

Title: Ambroxol effects in glucocerebrosidase and α-synuclein transgenic mice.
Authors: Migdalska-Richards A, Daly L, Bezard E, Schapira AH.
Journal: Ann Neurol. 2016 Nov;80(5):766-775.
PMID: 27859541            (This article is OPEN ACCESS if you would like to read it)

In this study, the researchers treated mice with Ambroxol for 12 days and then measured the level of glucocerebrosidase activity in the brain. They gave Ambroxol to three different groups of mice:

  • a group of normal mice,
  • a group of mice which had been genetically engineered with a specific mutation in their GBA gene (the heterozygous L444P mutation)
  • a group of mice that produced human alpha synuclein (the protein closely associated with Parkinson’s disease).

When they looked at the level of glucocerebrosidase enzyme activity in normal mice, they found an increase of approximately 20% (in mice treated with 4mM Ambroxol). One curious finding was that this dose was the only dose that increase glucocerebrosidase activity (1, 3, and 5mM of Ambroxol had no effect). The investigators noted, however, a reduction in water drinking of mice receiving 5mM in their drinking water (maybe they didn’t like the taste of it!), suggesting that they were not getting as much Ambroxol as the 4mM group.

The 4mM level of of Ambroxol also increased glucocerebrosidase activity in the L444P mutation mice and the alpha-synuclein mice (which interestingly also has reduced levels of glucocerebrosidase activity). One important observation in the alpha synuclein mice was the finding that Ambroxol was able to reduce the levels of alpha synuclein in the cells, indicating better clearance of un-wanted excess of proteins.

These combined results suggested to the investigators that Ambroxol is entering the brain of mice (passing through the protective blood brain barrier) and able to be effective there. In addition, they did not witness any serious adverse effects of ambroxol administration in the mice – an observation made in other studies of Ambroxol in normal mice (Click here to read more about this).

These studies have been followed up by a dosing study in primates which was just published:

Ambrox

Title: Oral ambroxol increases brain glucocerebrosidase activity in a nonhuman primate.
Authors: Migdalska-Richards A, Ko WK, Li Q, Bezard E, Schapira AH.
Journal: Synapse. 2017 Mar 12. doi: 10.1002/syn.21967.
PMID: 28295625            (This article is OPEN ACCESS if you would like to read it)

In this study, the investigators analysed the effect of Ambroxol treatment on glucocerebrosidase activity in three healthy non-human primates. One subject was given an ineffective control solution vehicle, another subject received 22.5 mg/day of Ambroxol and the third subject received 100 mg/day of Ambroxol. They showed that daily administration 100 mg/day of Ambroxol results in increased levels of glucocerebrosidase activity in the brain (approximately 20% increase on average across different areas of the brain). Importantly, the 22.5 mg treatment did not result in any increase.

The investigators wanted to determine if the effect of Ambroxol was specific to glucocerebrosidase, and so they analysed the activity of another lysosome enzyme called beta-hexosaminidase (HEXB). They found that 100 mg/day of Ambroxol also increased HEXB activity (again by approximately 20%), suggesting that Ambroxol may be having an effect on other lysosome enzymes and not just glucocerebrosidase.

The researches concluded that these results provide the first data of the effect of Ambroxol treatment on glucocerebrosidase activity in the brain of non-human primates. In addition, the results indicate that Ambroxol is active and as the researchers wrote “should be further investigated in the context of clinical trials as a potential treatment for Parkinson’s disease”.

And there is a clinical trial currently underway?

Yes indeed.

Funded by the Cure Parkinson’s Trust and the Van Andel Research Institute (USA), there is currently a phase I clinical trial with 20 people with Parkinson’s disease receiving Ambroxol over 24 months. Importantly, the participants being enrolled in the study have both Parkinson’s disease and a mutation in their GBA gene. The study is being led by Professor Anthony Schapira at the Royal Free Hospital (London).

EDITORS NOTE HERE: Readers may be interested to know that Prof Schapira is also involved with another clinical trial for GBA-associated Parkinson’s disease. The work is being conducted in collaboration with the biotech company Sanofi Genzyme, and involves a phase II trial, called MOVE-PD, which is testing the efficacy, and safety of a drug called GZ/SAR402671 (Click here to read more about this clinical trial). GZ/SAR402671 is a glucosylceramide synthase inhibitor, which will hopefully reduce the production and consequent accumulation of glycosphingolipids in people with a mutation in the GBA gene. This approach is trying to reduce the amount of protein that can not be broken down by the faulty glucocerebrosidase enzyme. The MOVE-PD study will enroll more than 200 patients worldwide (Click here and here to read more on this).

The current Phase 1 trial at the Royal Free Hospital will be primarily testing the safety of Ambroxol in GBA-associated Parkinson’s disease. The researchers will, however, be looking to see if Ambroxol can increase levels of glucocerebrosidase and also assess whether this has any beneficial effects on the Parkinson’s features.

So what does it all mean?

There is a major effort from many of the Parkinson’s disease related charitable groups to clinically test available medications for their ability to slow this condition. Big drug companies are not interested in this ‘re-purposing effort’ as many of these drugs are no longer patent protected and thus providing limited profit opportunities for them. This is one of the unfortunate realities of the pharmaceutical industry business model.

One of the most interesting drugs being tested in this re-purposing effort is the respiratory disease-associated treatment, Ambroxol. Recently new research has been published that indicates Ambroxol is able to enter the brain and have an impact by increasing the level of protein disposal activity.

A clinical trial testing Ambroxol in Parkinson’s disease is underway and we will be watching for the results when they are released (most likely late 2019/early 2020, though preliminary results may be released earlier).

This trial is worth watching.

Stay tuned.


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. Amboxol is a commercially available medication, but it is not without side effects (for more on this, see this website). We urge caution and professional consultation before altering a treatment regime. SoPD can not be held responsible for any actions taken based on the information provided here. 


The banner for today’s post was sourced from Pharmacybook

Editorial: Putting 200 years into context

200

Here at the SoPD we understand and are deeply sympathetic to the frustration felt by the Parkinson’s community regarding the idea of ‘200 years and still no cure’.

As research scientists, we are in the trench everyday – fighting the good fight – trying to find ways of alleviating this terrible condition. And some of us are also in the clinics, interacting with sufferers and their families, listening to their stories and trying to help. While we do not deal directly with the day-to-day trials of living with Parkinson’s disease, we are keenly aware of many of the issues and are fully invested in trying to correct this condition.

972px-Paralysis_agitans_(1907,_after_St._Leger)

Source: Wikipedia

We do feel, however, that it is important to put some context into that ‘200 years’ time point that we are observing this week. It is too easy for people to think “wow, 200 years and still no cure?”

In our previous post – made in collaboration with Prof Frank Church of the Journey with Parkinson’s blog – we listed the major historical milestones and discoveries made in the Parkinson’s disease field during the last 200 years.

The most striking feature of that time line, however, is how just little actually happened during the first 100 years.

In fact for most of that period, Parkinson’s disease wasn’t even called ‘Parkinson’s disease’.

Of the 48 events that we covered on that time line, 37 of them have occurred in the last 50 years (26 since 2000).

Taking this line of thought one step further, 2017 is also the 20 year anniversary of the discovery of alpha synuclein‘s association with Parkinson’s disease. And what a remarkable 20 years that has been. In 1997, a group of researcher at the National institute of Health led by Robert Nussbaum reported the first genetic mutation in the alpha synuclein gene that infers vulnerability to Parkinson’s disease.

Since then, we have:

  • identified multiple additional mutations within that same gene that increase the risk of developing Parkinson’s disease.
  • determined which forms of alpha synuclein are toxic.
  • identified alpha synuclein as an important component of Lewy bodies – the dense clusters of protein found in the Parkinsonian brain.
  • discovered numerous methods by which alpha synuclein can be passed between cells – potentially aiding in the spread of Parkinson’s disease.
  • developed and validated models of Parkinson’s disease based on manipulations of alpha synuclein (including numerous genetically engineered mice, viral over-expression models, etc).
  • identified alpha synuclein in the lining of the gut of people with Parkinson’s disease and this has aided us in developing new theories as to how the condition may start.
  • set up and run numerous clinical trials targeting alpha synuclein (and we eagerly await the results of those trials).
  • published over 6200 scientific papers (don’t believe me? Click here) – that’s over 300 publications per year!

PBB_Protein_SNCA_image

Alpha synuclein protein. Source: Wikipedia

And the truly amazing part? All of these particular achievements are only dealing with just the one gene: alpha synuclein.

Since the identification of the alpha synuclein mutations, we have subsequently discovered genetic mutations in over 20 other genes that increase the risk of developing Parkinson’s disease. And we have conducted the same activities/experiments for most of those genes as we have for alpha synuclein.

For example, in 2004 we discovered that people with genetic mutations in a gene called glucocerebrosidase (or GBA) had an increased risk of developing Parkinson’s disease. In 2016, just 12 years after that discovery we have started a clinical trial designed specifically for those people (Click here for more on this).

wwwnew2_0

Source: Parkinson’s UK

We here at the SoPD are fully supportive of campaigns like #WeWontWait, and this post was not written (nor meant to be taken) as an excuse response to the ‘200 years and no cure’ frustration. I can understand how it may be read that way, but I did not know how else to write it. And I thought it needed to be written.

The point of this entire post is that those 200 years need to be put into context.

And while all of these words aren’t going to make life easier for someone living with Parkinson’s to deal with their situation, in addition to raising awareness this week I think it is important for the Parkinson’s community to also understand just how far we have come, and how fast we are currently progressing.

The question can be asked: will this be the last major anniversary we acknowledge with regards to Parkinson’s disease?

I sincerely think that there is cause to hope that it is.


 

Let me finish with a personal note:

I have a good friend – let’s call him Matt.

As a young boy, Matt remembers his grandfather having Parkinson’s disease. He remembers growing up watching the trials and tribulations that the old man went through with the condition. There were basically no treatment options when Matt’s grandfather was diagnosed and little in the way of support for the family. His grandfather’s body simply froze up as the disease progressed. L-dopa probably only became available to Matt’s grandfather during the latter stages of the disease.

Four years ago Matt’s father was diagnosed with Parkinson’s disease.

Thanks to scientific advances, however, Matt’s dad now has a wide range of treatment options on the medication side of things. The disease can be managed so that he can still play his golf and enjoy his retirement – in a way that his own father never could. He also has numerous surgical options once those medications lose their effectiveness (eg. deep brain stimulation, Pallidotomy, etc). The chances are very likely that Matt’s father will pass on by natural causes before he requires many of those additional options.

This is the progress that we have made.

But there is still a lot of work to be done of course.

During a lunch shortly after his father’s diagnosis, Matt looked squarely across the table at me. Me, the Parkinson’s researcher. All of the usual jovial nature was missing from his face and he simply muttered the words ‘hurry up’.

Whether he was speaking for his father, himself or his own young kids, I understood where his words were coming from and the sentiment.

And, as this post and the previous post point out, we are hurrying up.


The banner for today’s post was sourced from BMO

Identical twins and Parkinson’s disease

Twins

The influence of genetics in  Parkinson’s disease is difficult to determine. If it was simply a genetic disease, identical twins – who share identical DNA – should show no difference in their susceptibility to Parkinson’s disease. They should either both develop the condition, or not. Right?

But this is not the case.

In today’s post we will review a particularly interesting pair of identical twins.


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Jeff & Jack Gernsheimer in 1982. Source: ReadingEagle 

When people ask the obvious question about the cause of Parkinson’s disease – ‘is it genetics or is it environment?’ – I have a standard answer: ‘it’s complicated’. I then tell them the curious story of identical twins Jeff and Jack Gernsheimer from eastern Pennsylvania. No other case better demonstrates the strange question of what causes Parkinson’s disease.

For almost their entire lives (69 years), Jeff and Jack have lived no more than half a mile apart. Breathing the same air, drinking the same water. They are literally neighbours – just a five-minute walk between their homes. In addition, since 1971 they have worked in the same office at a graphic design firm that they started together. The brothers were the focus of a story in the online magazine Nautilus last year. It’s a fantastic article and I fully recommend you read it.

So here’s the thing: In 2009 Jack was diagnosed with Parkinson’s disease.

To date, Jeff is yet to exhibit any signs of the condition.

Strange huh?

Two genetically identical people, living in the exact same environment and one of them develops Parkinson’s disease.

Ok, how do we explain this?

Hang on a second, slow down. I haven’t even got to the really interesting part yet:

After being diagnosed, Jack had his genome sequenced to see if there were any particular genetic mutations that might make him vulnerable to Parkinson’s disease. That analysis determined that Jack has a mutation in the most common Parkinson’s disease-associated gene: Glucocerebrosidase or GBA (which we have discussed in a previous blog post).

Interesting. So that explains the Parkinson’s disease?

No. Jack’s identical twin brother, Jeff, also has that exact same mutation.

So now we have a pair of identical twins who share the identical genetic code, live in the same environment, and have a genetic mutation associated with Parkinson’s disease, but only Jack has developed the condition while Jeff has not.

I think you will agree, it’s a really interesting tale… and with the help of modern science, it gets even more interesting.

How so?

In 2014, a research paper was published that utilized cells from both Jack & Jeff to determine what differences existed between them:

twinstitle2

Title: iPSC-derived dopamine neurons reveal differences between monozygotic twins discordant for Parkinson’s disease.
Authors: Woodard CM, Campos BA, Kuo SH, Nirenberg MJ, Nestor MW, Zimmer M, Mosharov EV, Sulzer D, Zhou H, Paull D, Clark L, Schadt EE, Sardi SP, Rubin L, Eggan K, Brock M, Lipnick S, Rao M, Chang S, Li A, Noggle SA.
Journal: Cell Reports. 2014 Nov 20;9(4):1173-82.
PMID: 25456120        (this article is OPEN ACCESS if you would like to read it)

EDITOR’S NOTE HERE: Monozygotic means twins from the same egg, (as opposed to dizygotic meaning twins from two eggs). And discordant means ‘at variance, or at odds’ – in medicine it is used when one identical twin has a condition and the other does not.

The researchers conducting this study took skin cells from the brothers and they turned them into brain cells via a miraculous Nobel-prize winning approach. The technique firstly involves turning the skin cells into induced pluripotent stem cells (or iPS cells).

IPS-cells

Source: Csiro

iPS cells can be used to make any cell you wish, and the researchers encouraged Jack and Jeff’s iPS cells to develop into dopamine neurons (one of the types of cells that are vulnerable in Parkinson’s disease).

When the researchers analysed the dopamine neurons from both twins, they found that both had half the normal levels GBA protein activity (an enzymatic reaction) due to the mutation in the GBA gene. The brother’s dopamine neurons also had approximately three times the normal levels of alpha-synuclein protein, and a reduced capacity to synthesize and release dopamine.

fce5078fbe8ec74e95c8a435e607ad11

Dopamine neurons. Source: MindsofMalady

Then the researchers noticed something interesting: the dopamine cells from Jack (the affected twin) had lower dopamine levels than Jeff’s cells. This was rather strange: identical twins should actually have similar levels – all things being equal. The researchers attributed this decrease in dopamine to an increase in the levels of monoamine oxidase B (MAO-B) in Jack’s cells.

What is MAO-B?

Good question. MAO-B is an enzyme in dopamine neurons that helps to break down excess dopamine. After a cell releases dopamine, the cell will re-collect and recycle leftover/unused dopamine. MAO-B is the enzyme that breaks dopamine down. MAO-B inhibitors (such as Rasagiline or Azilect) have been used for some time as a therapy in Parkinson’s disease. By blocking MAO-B with MAO-B inhibitors, people with Parkinson’s disease can have increased levels of dopamine as the remaining dopamine does not get broken down so quickly.

The researchers studying Jack and Jeff’s iPS dopamine neurons found that by replacing the reduced GBA and inhibiting the oversupply of MAO-B (with MAO-B inhibitors) they made the dopamine neurons healthier – with an increase in dopamine levels and increased removal of excessive alpha-synuclein (the protein that is associated with Parkinson’s disease).

Are Jeff and Jack in a unique situation?

Nope. Not at all.

Here are some other examples:

ID-twin3

Title: Pathology of PD in monozygotic twins with a 20-year discordance interval.
Author: Dickson D, Farrer M, Lincoln S, Mason RP, Zimmerman TR Jr, Golbe LI, Hardy J.
Journal: Neurology. 2001 Apr 10;56(7):981-2.
PMID: 11294946

This was a case study in which a pair of identical twins both developed Parkinson’s disease, but one of the twins was diagnosed 20 years before the other.

ID-twin1

Title: Identical twins with Leucine rich repeat kinase type 2 mutations discordant for Parkinson’s disease.
Authors: Xiromerisiou G, Houlden H, Sailer A, Silveira-Moriyama L, Hardy J, Lees AJ.
Journal: Movement Disord. 2012 Sep 1;27(10):1323.
PMID: 22488887                (This article is OPEN ACCESS if you would like to read it)

This second case study involved a pair of twins who both carried a mutation in the Parkinson’s associated gene, Lrrk2 (click here to read more about this gene). They both developed Parkinson’s disease, but 10 years separated their diagnoses.

Twins1

Title: Parkinson disease in twins: an etiologic study.
Authors: Tanner CM, Ottman R, Goldman SM, Ellenberg J, Chan P, Mayeux R, Langston JW.
Journal: JAMA. 1999 Jan 27;281(4):341-6.
PMID: 9929087     (This article is OPEN ACCESS if you would like to read it)

In this study, the scientists screened 19,842 white male twins enrolled in the National Academy of Sciences/National Research Council World War II Veteran Twins Registry. 163 pairs of twin were identified in which at least 1 twin had Parkinson’s disease (and medical records were available).

When diagnosis was made over the age of 50 years of age, approximately 10% of the twin pairs both had Parkinson’s disease (for both monozygotic and dizygotic twins). But when diagnosis was made under the age of 50, the monozygotic concordance was 100% – that is, all of the identical twins diagnosed under the age of 50 had Parkinson’s disease – while the dizygotic concordance remained around 10-20%. The researchers concluded that ‘this pattern strongly supports a primarily inherited cause of early-onset Parkinson’s disease’.

So how do we explain the difference seen in Jack and Jeff?

Some twins may be born with a vulnerability for Parkinson’s disease (like a genetic mutation, in the GBA or Lrrk2 gene for example), but there is some other factor/s that is influential in the initiation of the disease. And this is where scientists start talking about something called epigenetics (Epi, Greek for ‘over’ or ‘above’ and Genetics,…well, you should be able to work that one out).

Epigenetics is the study of changes in an organism that are caused by modifications or variations of gene expression rather than alteration of the genetic code itself. These variations may result from external factors that cause genes to turn on and off.

sep-05-living-well-weizmann-epigenetics-robichek-dna

Source: 2ndActHealth

In the case of the Gernsheimer twins, if you read the story in the online magazine Nautilus you will find that their lives were not entirely the same. There were basic differences, for examples they went to different universities and in the 1970’s Jack enlisted in the army. But there were also some larger, life-altering differences: in the late 1980’s Jack lost a son in tragic circumstances. The brothers speculate that the stress/suffering associated with that particular event may have been a catalyst for the Parkinson’s that followed. Many researchers in the Parkinson’s disease field have speculated on whether a stressful/traumatic event in their lives was the causative agent for their Parkinson’s disease.

So what does it all mean?

It means that the answer is more complicated than first assumed. And unfortunately, this is where I end up when people ask me about ‘genetics vs environment’ in the cause of Parkinson’s disease: a qualified we really don’t know. But I do always suggest that ‘Genetics vs environment’ may be too simplistic.

 


The source of today’s banner was the AutismBlog.

Cleaning up with Ambroxol

Exciting news recently with the announcement of the Ambroxol study starting.

Exciting for two reasons:

  1. Ambroxol has the potential to make a major impact in the lives of some people with Parkinson’s disease.
  2. It illustrates how FAST things are moving in the world of Parkinson’s disease!

 

Inside each and every cell, there are millions of tiny actions taking place. Minute processes all working in a collective manner allowing the cell to function normally. There are lots of proteins helping to make other proteins, lots of proteins helping other proteins to get to where they need to be, and lots of proteins helping to break down other proteins after they have done their job.

All this activity generates a lot of waste. And a fundamental part of the activity in any cell is waste disposal. If that does not function properly, the cell is in serious trouble.

One of the most common genetic mutations associated with Parkinson’s disease – called GBA – results in cells having trouble getting rid of waste.

GBA-cartoon

Adapted from a cartoon by Dr Jing Pu. Source: The Nichd connection

What is GBA?

Glucocerebrosidase (or GBA) is an enzyme that helps with the recycling of waste. It is active in inside ‘lysosomes‘.

What are Lysosomes?

Lysosomes are small structures inside cells that act like recycling centers. Waste gets put inside the lysosome where enzymes like GBA help to break it down into useful parts. Mutations in the GBA gene can result in an abnormally short, non-functioning version of the enzyme. And in those cases the breaking down of waste inside the lysosome because inhibited.

What is the connection between GBA and Parkinson’s disease?

GBA mutations are the most common genetic anomaly associated with Parkinson’s disease. People with a mutation in their GBA gene are at higher risk of developing Parkinson’s disease than the general population. And people with Parkinson’s are approximately five times more likely to carry a GBA mutation than healthy control subjects.

So what is Ambroxol?

Ambroxol is a commonly used treatment for respiratory diseases. It promotes mucus clearance and eases coughing. Ambroxol is also anti-inflammatory, reducing redness in a sore throat.

Ok, but why the excitement for Parkinson’s disease?

In May of 2014 – less than 2 years ago – this study was published:

McNeil1

Title: Ambroxol improves lysosomal biochemistry in glucocerebrosidase mutation-linked Parkinson disease cells.
Authors: McNeill A, Magalhaes J, Shen C, Chau KY, Hughes D, Mehta A, Foltynie T, Cooper JM, Abramov AY, Gegg M, Schapira AH.
Journal: Brain. 2014 May;137(Pt 5):1481-95.
PMID: 24574503    (This report is OPEN ACCESS if you want to read it)

It was the first time that Ambroxol – a commercially available drug – had been tested in a Parkinson’s disease related context.

In this study the researchers collected skin cells (called fibroblasts) from eleven people with GBA mutations (some had been diagnosed with Parkinson’s disease). They measured the amount of glucocerebrosidase protein and enzyme activity in these cells, and they found that glucocerebrosidase enzyme activity was significantly reduced in fibroblasts from GBA mutations (on average just the enzyme was acting at just 5% of normal levels). They found that ambroxol increased glucosylceramidase activity in fibroblasts from people with GBA mutations AND in fibroblasts from healthy controls. Ambroxol treatment also reduced markers of oxidative stress in GBA mutant cells.

Given the increase in glucocerebrosidase activity after ambroxol treatment, the researchers wondered whether the drug would reduce alpha-synuclein levels in cells that were over-expressing this protein. Amazingly, after 5 days of ambroxol treatment, levels of alpha-synuclein had decreased significantly (15% on average 15%).

You can understand why the researchers were a little bit excited by these results. Here was a drug that re-activated the recycling unit in the cell and reduced levels of one of the main proteins associated with Parkinson’s disease. If the drug can reduce the levels of alpha synuclein in the brains of people with Parkinson’s disease, maybe the researchers will be able to slow down (or even halt) the disease!

Additional studies have now been reported which have confirmed the initial results.

And now the clinical trial?

Funded by the Cure Parkinson’s Trust and the Van Andel Research Institute (USA), it was announced this week that they had started recruiting subjects to be involved in a clinical trial at the Royal Free Hospital in London. The trial is a phase 1 study which will test the safety of Ambroxol in Parkinson’s disease. The researchers will also look to see if Ambroxol can increase levels of glucocerebrosidase and whether this has any beneficial effects in the subjects. The study will be conducted on 20 people with Parkinson’s disease who also have GBA mutations. They will be given the drug and followed over the next 24 months.

These are exciting times for the world of Parkinson’s disease as these drugs are no longer simply reducing the motor features of the condition, but actually attempting to slow/halt the disease.

And as we suggested at the start of the post the pace of these developments is becoming hard to keep up with.