Tagged: Substantia nigra

Voyager Therapeutics: Phase I clinical trial update

Today biotech company Voyager Therapeutics announced an update on their ongoing phase Ib clinical trial. The trial is evaluating the safety and tolerance of a gene therapy approach for people with advanced Parkinson’s.

Gene therapy is a technique that involves inserting new DNA into a cell using viruses. In this clinical trial, the virally delivered DNA helps the infected cell to produce dopamine in order to alleviate the motor features of Parkinson’s.

In today’s post we will discuss what gene therapy is, review the new results mentioned in the update, and look at other gene therapy approaches for Parkinson’s.



Source: Baltimoresun

Voyager Therapeutics is a clinical-stage gene therapy company that is focused on treatments for neurological conditions, such as Parkinson’s. Today the company announced an update of their ongoing Phase 1b trial of their product VY-AADC01 (Click here to see the press release).

VY-AADC01 represents a new class of treatment for Parkinson’s, as it is a form of gene therapy.

What is gene therapy?

The gene therapy involves introducing a piece of DNA into a cell which will cause the cell to produce proteins that they usually do not (either by nature or by mutation). The DNA is artificially inserted into cells and the cell’s protein producing machinery does the rest.

Source: Yourgenome

How does gene therapy work?

Continue reading

Advertisements

Mickey becomes more human?

For a long time researchers have lacked truly disease-relevant models of Parkinson’s.

We have loaded cells with toxins to cause cell death, we have loaded cells with mutant proteins to cause cell death, we have loaded cells with… well, you get the idea. Long story short though, we have never had proper models of Parkinson’s – that is a model which present all of the cardinal features of the condition (Lewy bodies, cell loss, and motor impairment).

The various models we have available have provided us with a wealth of knowledge about the biology of how cells die and how we can protect them, which has led to numerous experimental drugs being tested in the clinic. But there has always been a linger question of ‘how disease-relevant are these models?’

This situation may be about to change.

In today’s post we will look at new research in which Japanese researchers have genetically engineered mice in which they observed the generation of Lewy bodies, the loss of dopamine neurons and motor impairments. We will look at how these mice have been generated, and what it may tell us about Parkinson’s.


Walt Disney. Source: PBS

Ok, before we start today’s post: Five interesting facts about the animator Walt Disney (1901 – 1966):

  • Disney dropped out of high school at age 16 with the goal of joining the Army to help out in the war effort. He was rejected for being underage, but was able to get a job as an ambulance driver with the Red Cross in France.
  • From 1928 (the birth of Mickey Mouse) until 1947, Disney himself performed the voice of Mickey.
  • Mickey Mouse was originally named “Mortimer Mouse”, but it was Disney’s wife who suggested that the name Mortimer sounded too pompous (seriously, can you imagine a world with the “Mortimer Mouse show”?). She convinced Disney to change the name to Mickey (the name Mortimer was later given to one of Mickey’s rivals).
  • To this day, Disney holds the record for the most individual Academy Awards and nominations. Between 1932 and 1969, he won 22 Academy Awards and was nominated 59 times (Source).
  • And best of all: On his deathbed as he lay dying from lung cancer, Disney wrote the name “Kurt Russell” on a piece of paper. They were in effect his ‘last words’. But no one knows what they mean. Even Kurt is a bit perplexed by it all. He (along with many others) was a child actor contracted to the Disney company at the time, but why did Walt write Russell’s name as opposed to something more deep and meaningful (no disrespect intended towards Mr Russell).

Actor Kurt Russell. Source: Fxguide

When asked why he thought his great creation “Mickey mouse” was so popular, Walt Disney responded that “When people laugh at Mickey Mouse, it’s because he’s so human; and that is the secret of his popularity”.

Mickey Mouse. Source: Ohmy.Disney

This is a curious statement.

Curious because in biomedical research, mice are used in experiments to better understand the molecular pathways underlying basic biology and for the testing of novel therapeutics, and yet they are so NOT human.

There are major biological differences between us and them.

Not human. Source: USNews

It has been a major dilemma for the research community for some time with regards to translating novel therapies to humans, and it raises obvious ethical questions of whether we should be using mice at all for the basic research if they are so different from us. This problem is particularly apparent in the field of immunology, where the differences between ‘mice and men’ is so vast in some cases that researcher have called for moving away from mice entirely and focusing on solely human models (Click here and here for a good reads on this topic).

What does this have to do with Parkinson’s?

Continue reading

When the zombies are all in your head

In your brain there are different types of cells.

Firstly there are the neurons (the prima donnas that we believe do most of the communication of information). Next there are the microglia cells, which act as the first and main line of active immune defence in the brain. There are also oligodendrocyte, that wrap protective sheets around the branches of the neurons and help them to pass signals.

And then there are astrocytes.

These are the ‘helper cells’ which maintain a comfortable environment for the neurons and aid them in their task. Recently, researchers in California reported an curious observation in the Parkinsonian brain: some astrocytes have entered an altered ‘zombie’-like state. And this might not be such a good thing.

In today’s post, we’ll review the research and discuss what it could mean – if independently replicated – for the Parkinson’s community.


Zombies. Source: wallpapersbrowse

I don’t understand the current fascination with zombies.

There are books, movies, television shows, video games. All dealing with the popular idea of dead bodies wandering the Earth terrifying people. But why the fascination? Why does this idea have such appeal to a wide portion of the populous?

I just don’t get it.

Even more of a mystery, however, is where the modern idea of the ‘zombie’ actually came from originally.

You see, no one really knows.

Huh? What do you mean?

Some people believe that the word ‘zombie’ is derived from West African languages – ndzumbi means ‘corpse’ in the Mitsogo language of Gabon, and nzambi means the ‘spirit of a dead person’ in the Kongo language. But how did a word from the African continent become embedded in our psyche?

Others associate the idea of a zombie with Haitian slaves in the 1700s who believed that dying would let them return back to lan guinée (African Guinea) in a kind of afterlife. But apparently that freedom did not apply to situations of suicide. Rather, those who took their own life would be condemned to walk the Hispaniola plantations for eternity as an undead slave. Perhaps this was the starting point for the ‘zombie’.

More recently the word ‘zonbi’ (not a typo) appeared in the Louisiana Creole and the Haitian Creole and represented a person who is killed and was then brought to life without speech or free will.

Delightful stuff for the start of a post on Parkinson’s research, huh?

But we’re going somewhere with this.

Continue reading

Are Lewy bodies fake news?

One of the cardinal features of the Parkinsonian brain are dense, circular clusters of protein that we call ‘Lewy bodies’

But what exactly are these Lewy bodies?

How do they form?

And what function do they serve?

More importantly: Are they part of the problem – helping to cause of Parkinson’s? Or are they a desperate attempt by a sick cell to save itself?

In today’s post, we will have a look at new research that makes a very close inspection of Lewy bodies and finds some interesting new details that might tell us something about Parkinson’s.


Neuropathologists conducting a gross examination of a brain. Source: NBC

A definitive diagnosis of Parkinson’s disease can only be made at the postmortem stage with an examination of the brain. Until that moment, all cases of Parkinson’s disease are ‘suspected’.

When a neuropathologist makes an examination of the brain of a person who passed away with the clinical features of Parkinson’s, there are two characteristic hallmarks that they will be looking for in order to provide a final diagnosis of the condition:

1.  The loss of specific populations of cells in the brain, such as the dopamine producing neurons in a region called the substantia nigra, which lies in an area called the midbrain (at the base of the brain/top of the brain stem).

d1ea3d21c36935b85043b3b53f2edb1f87ab7fa6

The dark pigmented dopamine neurons in the substantia nigra are reduced in the Parkinson’s disease brain (right). Source:Memorangapp

2.  Dense, circular clusters (or aggregates) of protein within cells, which are called Lewy bodies.

shutterstock_227273575

A cartoon of a neuron, with the Lewy body indicated within the cell body. Source: Alzheimer’s news

What is a Lewy body?

A Lewy body is referred to as a cellular inclusion (that is, ‘a thing that is included within a whole’), as they are almost always found inside the cell body. They generally measure between 5–25 microns in diameter (5 microns is 0.005 mm) thus they are tiny, but when compared to the neuron within which they reside they are rather large (neurons usually measures 40-100 microns in diameter).

A photo of a Lewy body inside of a neuron. Source: Neuropathology-web

How do Lewy bodies form? And what is their function?

The short answer to these questions is:

Source: Wellbeing365

The longer answer is: Our understanding of how Lewy bodies are formed – and their actual role in neurodegenerative conditions like Parkinson’s – is extremely limited. No one has ever observed one forming. Lewy bodies are very difficult to generate in the lab under experimental conditions. And as for their function, this is the source of much guess work and serious debate (we’ll come back to this topic later in this post).

Ok, but what are Lewy bodies actually made of?

Continue reading

“Three hellos” for Parkinson’s

Trehalose is a small molecule – nutritionally equivalent to glucose – that helps to prevent protein from aggregating (that is, clustering together in a bad way).

Parkinson’s disease is a neurodegenerative condition that is characterised by protein aggregating, or clustering together in a bad way.

Is anyone else thinking what I’m thinking?

In today’s post we will look at what trelahose is, review some of the research has been done in the context of Parkinson’s disease, and discuss how we should be thinking about assessing this molecule clinically.


Neuropathologists examining a section of brain tissue. Source: Imperial

When a neuropathologist makes an examination of the brain of a person who passed away with Parkinson’s, there are two characteristic hallmarks that they will be looking for in order to provide a definitively postmortem diagnosis of the condition:

1.  The loss of dopamine producing neurons in a region of the brain called the substantia nigra.

d1ea3d21c36935b85043b3b53f2edb1f87ab7fa6

The dark pigmented dopamine neurons in the substantia nigra are reduced in the Parkinson’s disease brain (right). Source:Memorangapp

2.  The clustering (or ‘aggregation’) of a protein called alpha synuclein. Specifically, they will be looking for dense circular aggregates of the protein within cells, which are referred to as Lewy bodies.

A Lewy body inside of a neuron. Source: Neuropathology-web

Alpha-synuclein is actually a very common protein in the brain – it makes up about 1% of the material in neurons (and understand that there are thousands of different proteins in a cell, thus 1% is a huge portion). For some reason, however, in Parkinson’s disease this protein starts to aggregate and ultimately forms into Lewy bodies:

shutterstock_227273575

A cartoon of a neuron, with the Lewy body indicated within the cell body. Source: Alzheimer’s news

In addition to Lewy bodies, the neuropathologist may also see alpha synuclein clustering in other parts of affected cells. For example, aggregated alpha synuclein can be seen in the branches of cells (these clusterings are called ‘Lewy neurites‘ – see the image below where alpha synuclein has been stained brown on a section of brain from a person with Parkinson’s disease.

Lewy_neurites_alpha_synuclein

Examples of Lewy neurites (indicated by arrows). Source: Wikimedia

Given these two distinctive features of the Parkinsonian brain (the loss of dopamine neurons and the aggregation of alpha synuclein), a great deal of research has focused on A.) neuroprotective agents to protect the remaining dopamine-producing neurons in the substantia nigra, and B.) compounds that stop the aggregation of alpha synuclein.

In today’s post, we will look at the research that has been conducted on one particular compounds that appears to stop the aggregation of alpha synuclein.

It is call Trehalose (pronounces ‘tray-hellos’).

Continue reading

Are we getting NURR to the end of Parkinson’s disease?

Nuclear receptor related 1 protein (or NURR1) is a protein that is critical to the development and survival of dopamine neurons – the cells in the brain that are affected in Parkinson’s disease.

Given the importance of this protein for the survival of these cells, a lot of research has been conducted on finding activators of NURR1.

In today’s post we will look at this research, discuss the results, and consider issues with regards to using these activators in Parkinson’s disease.


Comet Hale–Bopp. Source: Physics.smu.edu

Back in 1997, 10 days after Comet Hale–Bopp passed perihelion (April 1, 1997 – no joke; perihelion being the the point in the orbit of a comet when it is nearest to the sun) and just two days before golfer Tiger Woods won his first Masters Tournament, some researchers in Stockholm (Sweden) published the results of a study that would have a major impact on our understanding of how to keep dopamine neurons alive.

Dopamine neurons are one group of cells in the brain that are severely affected by Parkinson’s disease. By the time a person begins to exhibit the movement symptoms of the condition, they will have lost 40-60% of the dopamine neurons in a region called the substantia nigra. In the image below, there are two sections of brain – cut on a horizontal plane through the midbrain at the level of the substantia nigra – one displaying a normal compliment of dopamine neurons and the other from a person who passed away with Parkinson’s demonstrating a reduction in this cell population.

d1ea3d21c36935b85043b3b53f2edb1f87ab7fa6

The dark pigmented dopamine neurons in the substantia nigra are reduced in the Parkinson’s disease brain (right). Source:Memorangapp

The researchers in Sweden had made an amazing discovery – they had identified a single gene that was critical to the survival of dopamine neurons. When they artificially mutated the section of DNA where this gene lives – an action which resulted in no protein for this gene being produced – they generated genetically engineered mice with no dopamine neurons:

Title: Dopamine neuron agenesis in Nurr1-deficient mice
Authors: Zetterström RH, Solomin L, Jansson L, Hoffer BJ, Olson L, Perlmann T.
Journal: Science. 1997 Apr 11;276(5310):248-50.
PMID: 9092472

The researchers who conducted this study found that the mice with no NURR1 protein exhibited very little movement and did not survive long after birth. And this result was very quickly replicated by other research groups (Click here and here to see examples)

So what was this amazing gene called?

Continue reading

Voyager Therapeutics: phase Ib clinical trial results

 

This week a biotech company called Voyager Therapeutics announced the results of their ongoing phase Ib clinical trial. The trial is investigating a gene therapy approach for people with severe Parkinson’s disease.

Gene therapy is a technique that involves inserting new DNA into a cell using a virus. The DNA can help the cell to produce beneficial proteins that go on help to alleviate the motor features of Parkinson’s disease.

In today’s post we will discuss gene therapy, review the new results and consider what they mean for the Parkinson’s community.


Source: Joshworth

On 25th August 2012, the Voyager 1 space craft became the first human-made object to exit our solar system.

After 35 years and 11 billion miles of travel, this explorer has finally left the heliosphere (which encompasses our solar system) and it has crossed into the a region of space called the heliosheath – the boundary area that separates our solar system from interstellar space. Next stop on the journey of Voyager 1 will be the Oort cloud, which it will reach in approximately 300 years and it will take the tiny craft about 30,000 years to pass through it.

Where is Voyager 1? Source: Tampabay

Where is Voyager actually going? Well, eventually it will pass within 1 light year of a star called AC +79 3888 (also known as Gliese 445), which lies 17.6 light-years from Earth. It will achieve this goal on a Tuesday afternoon in 40,000 years time.

Gliese 445 (circled). Source: Wikipedia

Remarkably, the Gliese 445 star itself is actually coming towards us. Rather rapidly as well. It is approaching with a current velocity of 119 km/sec – nearly 7 times as fast as Voyager 1 is travelling towards it (the current speed of the craft is 38,000 mph (61,000 km/h).

Interesting, but what does any of that have to do with Parkinson’s disease?

Well closer to home, another ‘Voyager’ is also ‘going boldly where no man has gone before’ (sort of).

Continue reading

Dementia with Lewy Bodies: New recommendations

jnnp-2015-January-86-1-50-F1.large

Last year – two years after actor Robin Williams died – his wife Susan Schneider Williams wrote an essay entitled The terrorist inside my husband’s head, published in the journal Neurology.

It is a heartfelt/heartbreaking insight into the actor’s final years. It also highlights the plight of many who are diagnosed with Parkinson’s disease, but experience an array of additional symptoms that leave them feeling that something else is actually wrong.

Today’s post is all about Dementia with Lewy bodies (or DLB). In particular, we will review the latest refinements and recommendations of the Dementia with Lewy Bodies Consortium, regarding the clinical and pathologic diagnosis of DLB.


robin-williams

Robin Williams. Source: Quotesgram

On the 28th May of 2014, the actor Robin Williams was diagnosed with Parkinson’s disease.

At the time, he had a slight tremor in his left hand, a slow shuffling gait and mask-like face – some of the classical features of Parkinson’s disease.

According to his wife, the diagnosis gave the symptoms Robin had been experiencing a name. And this brought her a sense of relief and comfort. Now they could do something about the problem. Better to know what you are dealing with rather than be left unsure and asking questions.

But Mr Williams sensed that something else was wrong, and he was left unsure and asking questions. While filming the movie Night at the Museum 3, Williams experienced panic attacks and regularly forgot his lines. He kept asking the doctors “Do I have Alzheimer’s? Dementia? Am I schizophrenic?”

Williams took his own life on the 11th August 2014, and the world mourned the tragic loss of a uniquely talented performer.

Source: WSJ

When the autopsy report came back from the coroner, however, it indicated that the actor had been misdiagnosed.

He didn’t have Parkinson’s disease.

What he actually had was Dementia with Lewy bodies (or DLB).

What is Dementia with Lewy bodies?

Continue reading

The autoimmunity of Parkinson’s disease?

Auto

In this post we discuss several recently published research reports suggesting that Parkinson’s disease may be an autoimmune condition. “Autoimmunity” occurs when the defence system of the body starts attacks the body itself.

This new research does not explain what causes of Parkinson’s disease, but it could explain why certain brain cells are being lost in some people with Parkinson’s disease. And such information could point us towards novel therapeutic strategies.


Nature_cover,_November_4,_1869

The first issue of Nature. Source: SimpleWikipedia

The journal Nature was first published on 4th November 1869, by Alexander MacMillan. It hoped to “provide cultivated readers with an accessible forum for reading about advances in scientific knowledge.” It has subsequently become one of the most prestigious scientific journals in the world, with an online readership of approximately 3 million unique readers per month (almost as much as we have here at the SoPD).

Each Wednesday afternoon, researchers around the world await the weekly outpouring of new research from Nature. And this week a research report was published in Nature that could be big for the world of Parkinson’s disease. Really big!

On the 21st June, this report was published:

Nature
Title: T cells from patients with Parkinson’s disease recognize α-synuclein peptides
Authors: Sulzer D, Alcalay RN, Garretti F, Cote L, Kanter E, Agin-Liebes J, Liong C, McMurtrey C, Hildebrand WH, Mao X, Dawson VL, Dawson TM, Oseroff C, Pham J, Sidney J, Dillon MB, Carpenter C, Weiskopf D, Phillips E, Mallal S, Peters B, Frazier A, Lindestam Arlehamn CS, Sette A
Journal: Nature. 2017 Jun 21. doi: 10.1038/nature22815.
PMID: 28636593

In their study, the investigators collected blood samples from 67 people with Parkinson’s disease and from 36 healthy patients (which were used as control samples). They then exposed the blood samples to fragments of proteins found in brain cells, including fragments of alpha synuclein – this is the protein that is so closely associated with Parkinson’s disease (it makes regular appearances on this blog).

What happened next was rather startling: the blood from the Parkinson’s patients had a strong reaction to two specific fragments of alpha synuclein, while the blood from the control subjects hardly reacted at all to these fragments.

In the image below, you will see the fragments listed along the bottom of the graph (protein fragments are labelled with combinations of alphabetical letters). The grey band on the plot indicates the two fragments that elicited a strong reaction from the blood cells – note the number of black dots (indicating PD samples) within the band, compared to the number of white dots (control samples). The numbers on the left side of the graph indicate the number of reacting cells per 100,000 blood cells.

Table1

Source: Nature

The investigators concluded from this experiment that these alpha synuclein fragments may be acting as antigenic epitopes, which would drive immune responses in people with Parkinson’s disease and they decided to investigate this further.

Continue reading

A connection between ALS & Parkinson’s disease? Oh’ll, SOD it!

604ee0d6431dbd15f686133f6fa7205c

Please excuse our use of UK slang in the title of this post, but a group of Australian researchers have recently discovered something really interesting about Parkinson’s disease.

And being a patriotic kiwi, it takes something REALLY interesting for me to even acknowledge that other South Pacific nation. This new finding, however, could be big.

In today’s post, we will review new research dealing with a protein called SOD1, and discuss what it could mean for the Parkinson’s community.


d1ea3d21c36935b85043b3b53f2edb1f87ab7fa6

The number of dark pigmented dopamine cells in the substantia nigra are reduced in the Parkinson’s disease brain (right). Source: Adaptd from Memorangapp

Every Parkinson’s-associated website and every Parkinson’s disease researchers will tell you exactly the same thing when describing the two cardinal features in the brain of a person who died with Parkinson’s disease:

  1. The loss of certain types of cells (such as the dopamine producing cells of the substantia nigra region of the brain – see the image above)
  2. The clustering (or aggregation) of a protein called Alpha synuclein in tightly packed, circular deposits, called Lewy bodies (see image below).

9-lb2

A Lewy body inside a cell. Source: Adapted from Neuropathology-web

The clustered alpha synuclein protein, however, is not limited to just the Lewy bodies. In the affected areas of the brain, aggregated alpha synuclein can be seen in the branches of cells – see the image below where alpha synuclein has been stained brown on a section of brain from a person with Parkinson’s disease.

Lewy_neurites_alpha_synuclein

Examples of Lewy neurites (indicated by arrows). Source: Wikimedia

Now, one of the problems with our understanding of Parkinson’s disease is disparity between the widespread presence of clustered alpha synuclein and very selective pattern of cell loss. Alpha synuclein aggregation can be seen distributed widely around the affected areas of the brain, but the cell loss will be limited to specific populations of cells.

If the disease is killing a particular population of cells, why is alpha synuclein clustering so wide spread?

So why is there a difference?

We don’t know.

It could be that the cells that die have a lower threshold for alpha synuclein toxicity (we discussed this is a previous post – click here?).

But this question regarding the difference between these two features has left many researchers wondering if there may be some other protein or agent that is actually killing off the cells and then disappearing quickly, leaving poor old alpha synuclein looking rather guilty.

maxresdefault

Poor little Mr “A Synuclein” got the blame, but his older brother actually did it! Source: Youtube

And this is a very serious discussion point.

This year of 2017 represents the 200th anniversary of James Parkinson’s first description of Parkinson’s disease, but it also represents the 20th anniversary since the association between alpha synuclein and PD was first established. We have produced almost 7,000 research reports on the topic of alpha synuclein and PD during that time, and we currently have ongoing clinical trials targetting alpha synuclein.

But what if our basic premise – that alpha synuclein is the bad guy – is actually wrong?

Is there any evidence to suggest this?

We are just speculating here, but yes there is.

For example, in a study of 904 brains, alpha synuclein deposits were observed in 11.3% of the brains (or 106 cases), but of those cases only 32 had been diagnosed with a neurodegenerative disorder (Click here to read more on this). The remaining 74 cases had demonstrated none of the clinical features of Parkinson’s disease.

So what else could be causing the cell death?

Well, this week some scientists from sunny Sydney (Australia) reported a protein that could fit the bill.

sydney_cruises

Sydney. Source: Vagabond

The interesting part of their finding is that the protein is also associated with another neurodegenerative condition: Amyotrophic lateral sclerosis.

Remind me again, what is Amyotrophic lateral sclerosis?

Parkinson’s disease and Amyotrophic lateral sclerosis (ALS) are the second and third most common adult-onset neurodegenerative conditions (respectively) after Alzheimer’s disease. We recently discussed ALS in a previous post (Click here to read that post).

ALS, also known as Lou Gehrig’s disease and motor neuron disease, is a neurodegenerative condition in which the neurons that control voluntary muscle movement die. The condition affects 2 people in every 100,000 each year, and those individuals have an average survival time of two to four years.

You may have heard of ALS due to it’s association with the internet ‘Ice bucket challenge‘ craze that went viral in 2014-15.

ice-bucket-challenge

The Ice bucket challenge. Source: Forbes

What is the protein associated with ALS?

In 1993, scientists discovered that mutations in the gene called SOD1 were associated with familial forms of ALS (Click here to read more about this). We now know that mutations in the SOD1 gene are associated with around 20% of familial cases of ALS and 5% of sporadic ALS.

The SOD1 gene produces an enzyme called Cu-Zn superoxide dismutase.

This enzyme is a very powerful antioxidant that protects the body from damage caused by toxic free radical generated in the mitochondria.

Protein_SOD1_PDB_1azv

SOD1 protein structure. Source: Wikipedia

One important note here regarding ALS: the genetic mutations in the SOD1 gene do not cause ALS by affecting SOD1’s antioxidant properties (Click here to read more about this). Rather, researchers believe that the cell death seen in SOD1-associated forms of ALS is the consequences of some kind of toxic effect caused by the mutant protein.

So what did the Aussie researchers find about SOD1 in Parkinson’s disease?

This week, the Aussie researchers published this research report:

SOD
Title: Amyotrophic lateral sclerosis-like superoxide dismutase 1 proteinopathy is associated withneuronal loss in Parkinson’s disease brain.
Authors: Trist BG, Davies KM, Cottam V, Genoud S, Ortega R, Roudeau S, Carmona A, De Silva K, Wasinger V, Lewis SJG, Sachdev P, Smith B, Troakes C, Vance C, Shaw C, Al-Sarraj S, Ball HJ, Halliday GM, Hare DJ, Double KL.
Journal: Acta Neuropathol. 2017 May 19. doi: 10.1007/s00401-017-1726-6.
PMID: 28527045

Given that oxidative stress is a major feature of Parkinson’s disease, the Aussie researchers wanted to investigate the role of the anti-oxidant enzyme, SOD1 in this condition. And what they found surprised them.

Heck, it surprised us!

Two areas affected by Parkinson’s disease – the substantia nigra (where the dopamine neurons reside; SNc in the image below) and the locus coeruleus (an area in the brain stem that is involved with physiological responses to stress; LC in the image below) – exhibited little or no SOD1 protein in the control brains.

But in the Parkinsonian brains, there was a great deal of SOD1 protein (see image below).

401_2017_1726_Fig1_HTML

SO1 staining in PD brain and Control brains. Source: Springer

In the image above, you can see yellowish-brown stained patches in both the PD and control images. This a chemical called neuromelanin and it can be used to identify the dopamine-producing cells in the SNc and LC. The grey staining in the PD images (top) are cells that contain SOD1. Note the lack of SOD1 (grey staining) in the control images (bottom).

Approximately 90% of Lewy bodies in the Parkinson’s affected brains contained SOD1 protein. The investigators did report that the levels of SOD1 protein varied between Lewy bodies. But the clustered (or ‘aggregated’) SOD1 protein was not just present with alpha synuclein, often it was found by itself in the degenerating regions.

The researchers occasional saw SOD1 aggregation in regions of age-matched control brains, and they concluded that a very low level of SOD1 must be inherent to the normal ageing process.

But the density of SOD1 clustering was (on average) 8x higher in the SNc and 4x higher in the LC in the Parkinsonian brain compared to age-matched controls. In addition, the SOD1 clustering was significantly greater in these regions than all of the non-degenerating regions of the same Parkinson’s disease brains.

The investigators concluded that these data suggest an association between SOD1 aggregation and neuronal loss in Parkinson’s disease. Importantly, the presence of SOD1 aggregations “closely reflected the regional pattern of neuronal loss”.

They also demonstrated that the SOD1 protein in the Parkinsonian brain was not folded correctly, a similar characteristic to alpha synuclein. A protein must fold properly to be able to do it’s assigned jobs. By not folding into the correct configuration, the SOD1 protein could not do it’s various functions – and the investigators observed a 66% reduction in SOD1 specific activity in the SNc of the Parkinson’s disease brains.

Interestingly, when the researchers looked at the SNc and LC of brains from people with ALS, they identified SOD1 aggregates matching the SOD1 clusters they had seen in these regions of the Parkinson’s disease brain.

Is this the first time SOD1 has been associated with Parkinson’s disease?

No, but it is the first major analysis of postmortem Parkinsonian brains. SOD1 protein in Lewy bodies has been reported before:

1995

Title: Cu/Zn superoxide dismutase-like immunoreactivity is present in Lewy bodies from Parkinson disease: a light and electron microscopic immunocytochemical study
Authors: Nishiyama K, Murayama S, Shimizu J, Ohya Y, Kwak S, Asayama K, Kanazawa I.
Journal: Acta Neuropathol. 1995;89(6):471-4.
PMID: 7676802

The investigators behind this study reported SOD1 protein was present in Lewy bodies, in the substantia nigra and locus coeruleus of brains from five people with Parkinson’s disease. Interestingly, they showed that SOD1 is present in the periphery of the Lewy body, similar to alpha synuclein. Both of these protein are present on the outside of the Lewy body, as opposed to another Parkinson’s associated protein, Ubiquitin, which is mainly present in the centre (or the core) of Lewy bodies (see image below).

Lewy-bodies

A more recent study also demonstrated SOD1 protein in the Parkinsonian brain, including direct interaction between SOD1 and alpha synuclein:

Alspha

Title: α-synuclein interacts with SOD1 and promotes its oligomerization
Authors: Helferich AM, Ruf WP, Grozdanov V, Freischmidt A, Feiler MS, Zondler L, Ludolph AC, McLean PJ, Weishaupt JH, Danzer KM.
Journal: Mol Neurodegener. 2015 Dec 8;10:66.
PMID: 26643113              (This article is OPEN ACCESS if you would like to read it)

These researchers found that alpha synuclein and SOD1 interact directly, and they noted that Parkinson’s disease related mutations in alpha synuclein (A30P, A53T) and ALS associated mutation in SOD1 (G85R, G93A) modify the binding of the two proteins to each other. They also reported that alpha synuclein accelerates SOD1 aggregation in cell culture. This same group of researchers published another research report last year in which they noted that aggregated alpha synuclein increases SOD1 clustering in a mouse model of ALS (Click here for more on this).

We should add that alpha synuclein aggregations in ALS are actually quite common (click here and here to read more on this).

Are there any genetic mutations in the SOD1 gene that are associated with Parkinson’s disease?

Two studies have addressed this question:

genes

Title: Sequence of the superoxide dismutase 1 (SOD 1) gene in familial Parkinson’s disease.
Authors: Bandmann O, Davis MB, Marsden CD, Harding AE.
Journal: J Neurol Neurosurg Psychiatry. 1995 Jul;59(1):90-1.
PMID: 7608718                   (This article is OPEN ACCESS if you would like to read it)

And then in 2001, a second analysis:

Genes2

Title: Genetic polymorphisms of superoxide dismutase in Parkinson’s disease.
Authors: Farin FM, Hitosis Y, Hallagan SE, Kushleika J, Woods JS, Janssen PS, Smith-Weller T, Franklin GM, Swanson PD, Checkoway H.
Journal: Mov Disord. 2001 Jul;16(4):705-7.
PMID: 11481695

Both studies found no genetic variations in the SOD1 gene that were more frequent in the Parkinson’s affected community than the general population. So, no, there are no SOD1 genetic mutations that are associated with Parkinson’s disease.

Are there any treatments targeting SOD1 that could be tested in Parkinson’s disease?

Great question. Yes there are. And they have already been tested in models of PD:

als

Title: The hypoxia imaging agent CuII(atsm) is neuroprotective and improves motor and cognitive functions in multiple animal models of Parkinson’s disease.
Authors: Hung LW, Villemagne VL, Cheng L, Sherratt NA, Ayton S, White AR, Crouch PJ, Lim S, Leong SL, Wilkins S, George J, Roberts BR, Pham CL, Liu X, Chiu FC, Shackleford DM, Powell AK, Masters CL, Bush AI, O’Keefe G, Culvenor JG, Cappai R, Cherny RA, Donnelly PS, Hill AF, Finkelstein DI, Barnham KJ.
Title: J Exp Med. 2012 Apr 9;209(4):837-54.
PMID: 22473957               (This article is OPEN ACCESS if you would like to read it)

CuII(atsm) is a drug that is currently under clinical investigation as a brain imaging agent for detecting hypoxia (damage caused by lack of oxygen – Click here to read more about this).

The researchers conducting this study, however, were interested in this compound for other reasons: CuII(atsm) is also a highly effective scavenger of a chemical called ONOO, which can be very toxic. CuII(atsm) not only inhibits this toxicity, but it also blocks the clustering of alpha synuclein. And given that CuII(atsm) is capable of crossing the blood–brain barrier, these investigators wanted to assess the drug for its ability to rescue model of Parkinson’s disease.

And guess what? It did!

And not just in one model of Parkinson’s disease, but FOUR!

The investigators even waited three days after giving the neurotoxins to the mice before giving the CuII(atsm) drug, and it still demonstrated neuroprotection. It also improved the behavioural features of these models of Parkinson’s disease.

Is CuII(atsm) being tested for anything else in Clinical trials?

Yes, there is a clinical trial ongoing for ALS in Australia.

The Phase I study, being run by Collaborative Medicinal Development Pty Limited, is a dose escalating study of Cu(II)ATSM to determine if this drug is safe for use in ALS (Click here for more on this study).

static1.squarespace

Cu(II)ATSM is an orally administered drug that inhibits the activity of misfolded SOD1 protein. It has been shown to paradoxically increase mutant SOD1 protein in a mouse model of ALS, but it also provides neuroprotection and improves the outcome for these mice (Click here to read more on this).

If this trial is successful, it would be interesting to test this drug on a cohort of people with Parkinson’s disease. Determining which subgroup of the Parkinson’s affected community would most benefit from this treatment is still to be determined. There is some evidence published last year that suggests people with genetic mutations in the Parkinson’s associated gene PARK2 could benefit from the approach (Click here to read more on this). More research, however, is needed in this area.

So what does it all mean?

Right, so summing up, a group of Australian researchers have reported that the ALS associated protein SOD1 is closely associated with the cell death that we observe in the brains of people with Parkinson’s disease.

They suggest that this could highlight a common mechanisms of toxic SOD1 aggregation in both Parkinson’s disease and ALS. Individuals within the Parkinson’s affected community do not appear to have any genetic mutations in the SOD1 gene, which makes this finding is very interesting.

What remains to be determined is whether SOD1 aggregation is a “primary pathological event”, or if it is secondary to some other disease causing agent. We are also waiting to see if a clinical trial targeting SOD1 in ALS is successful. If it is, there may be good reasons for targeting SOD1 as a novel treatment for Parkinson’s disease.


The banner for today’s post was sourced from Pinterest