New research – the disorder of Alpha Synuclein

A couple of interesting scientific papers were published this week dealing with the Parkinson’s disease-related protein, Alpha Synuclein. If you are not familiar with it, we suggest that you check out our primer page on Alpha Synuclein before reading any further.

So, what’s new in the world of Alpha Synuclein?

Two studies.

One in the prestigious journal Nature and the other in her sister Nature Communications. Both studies came from the same lab (good job guys!)

The first study :

Theillet-title

Title: Structural disorder of monomeric α-synuclein persists in mammalian cells.
Authors: Theillet FX, Binolfi A, Bekei B, Martorana A, Rose HM, Stuiver M, Verzini S, Lorenz D, van Rossum M, Goldfarb D, Selenko P.
Journal: Nature. 2016 Jan 25.
PMID: 26808899

This first study presented a very detailed analysis of the structure of alpha synuclein – at the atomic level – inside living cells.

Interestingly, when the researchers injected alpha synuclein (at concentrations that have been observed in normal neurons) into 5 different types of cells (both neuron and others types), they found that the protein remains extremely disordered – it changed shape rapidly. They determined this by using nuclear magnetic resonance spectroscopy (try saying that 3 times really fast!), which provides a shallow peak readout for stable proteins and a sharp peak for disordered proteins (see image below).

nature16871-f1

The researchers found a lot of sharp peaks in cells that they injected Alpha Synuclein into. Source: Nature

Rather remarkably, despite the fact that disordered proteins are usually removed from cells by enzymatic degradation, the alpha synuclein that was injected by these researchers appears to have remained intact in the cells for several days (50+ hours). And the cells did not seem to be adversely affected by this.

The second Alpha Synuclein study published this week illustrated an equally interesting result:

Binolfi-title

Title: Intracellular repair of oxidation-damaged α-synuclein fails to target C-terminal modification sites.
Authors: Binolfi A, Limatola A, Verzini S, Kosten J, Theillet FX, May Rose H, Bekei B, Stuiver M, van Rossum M, Selenko P.
Journal: Nature Communications, 2016 Jan 25;7:10251.
PMID: 26807843

In this study, the researchers injected damaged alpha synuclein into cells and then watched the cells try to repair that damaged protein. There are specific enzymes that help to maintain/repair proteins like Alpha Synuclein inside each cell. This is a normal recycling process for cells, but something interesting happened with this damaged version of alpha synuclein: only one end of the protein was repaired. The other end (called the C-terminus) was left damaged and this end failed to function correctly.

fnins-09-00059-g001

The structure of Alpha Synuclein. The c-terminus is the area in red. Source: Frontiers in Neuroscience

This led the authors to conclude that damage can cause the accumulation of chemically and functionally altered Alpha Synuclein in cells.

What does this mean for Parkinson’s disease?

The results are very interesting and the researchers should be congratulated on the complexity of their work. The findings add to our understanding of Alpha Synuclein, but both of these results need to be replicated and expanded on before we can fully appreciate their impact.

One possible implications of the results is that designing drugs to target Alpha Synuclein may be more complicated than originally thought. If the protein remains as disordered as the first study suggests, it could be difficult to target. Further investigations, however, focused on the c-terminus end of Alpha synuclein may offer novel targets for therapies looking to clear damaged proteins from cells.

If Alpha Synuclein is the big, bad enemy in Parkinson’s disease, we now know a lot more about him and we can focus on his weaknesses.

The vulnerability of dopamine cells in the brain

The classical clinical motor features of Parkinson’s disease (slowness of movement, rigidity and a resting tremor in one of the limbs) are associated with the loss 60% of the dopamine neurons in the midbrain.

What does this mean?

The midbrain is a structure at the top of the spinal cord – just as you enter the brain proper – and dopamine is a chemical that is produced in the brain. The dopamine neurons in the midbrain form connections with different areas of the brain, and are involved in many basic neurological functions, such as movement, motivation and addiction.

CD-Pathology-Parkinson'sDisease Chptr19-Fig 19-3 Parkinson DiseaseGrossMidbrain copy

Sections of the human midbrain from a healthy individual (left) and a person who had Parkinson’s disease (right). The dopamine cells in the control subject can be seen on both sides of the brain with the eye because they produce a chemical (neuromelanin) that makes them black. These cells are noticeably absent in the Parkinsonian brain. Source: Springer

Not all midbrain dopamine neurons are affected in the same way in Parkinson’s disease though.

There are three basic groupings of dopamine neurons in the midbrain region:

  • The substantia nigra pars compacta (or SNC)
  • The ventral tegmental area (or VTA)
  • The retrorubral fields (this is a very small group compared with the VTA and SNC)

Subdivisions

As the image above illustrates the SNC is divided into two regions – a dorsal layer and a ventral layer.

It has been acknowledged for a long time that the dopamine neurons in the SNC are more vulnerable in Parkinson’s disease than dopamine neurons in the VTA. We have no idea why this specific vulnerability exists. A great deal of attention has been focused on the SNC as a result.

The vulnerability of the SNC dopamine neurons when compared to the VTA, however, is not as clear as many researchers would believe.

In an interesting study published last year, some researchers from the University of Iowa, reviewed previous studies of postmortem analysis of the brains of people with Parkinson’s disease, in particular, focusing on the studies that had counted the number of dopamine neurons in the VTA and the SNC. The results were very interesting:

VTA-title

Title: The Vulnerable Ventral Tegmental Area in Parkinson’s Disease.
Authors: Alberico SL, Cassell MD, Narayanan NS.
Journal: Basal Ganglia. 2015 Aug 1;5(2-3):51-55.
PMID: 26251824

In essence, the study was very simple: the researchers compared the percentage of VTA and SNC dopamine neurons lost in Parkinson’s disease as determined by eight previous studies. They then conducted their own postmortem analysis and compared the results.

In their review of the previous studies, the researchers found that while the SNC was more vulnerable in Parkinson’s disease (approximately 70% of the dopamine neurons are lost), the VTA region still lost 50% of it’s dopamine neurons (see table below).

VTA-table

Curiously, the researcher’s own postmortem analysis found that the VTA was actually more vulnerable than the SNC. Their analysis, however, was based on only 3 brains. In addition, questions can be raised as to how the previous studies defined the borders of the SNC and VTA. Difference exist in those delineations of borders, which may impact on the number of dopamine neurons counted in each region.

The important message, however, is that the VTA is also badly affected in Parkinson’s disease. And given that the VTA is a region involved in mood and motivation, acknowledging its involvement in the disease will help to focus more research attention on to those areas of functioning in Parkinson’s.

 

New research – Urate and Parkinson’s

New research this week lends further support to ongoing clinical trials focused on urate in Parkinson’s disease:

urate

Title: Prospective study of plasma urate and risk of Parkinson disease in men and women.
Authors: Gao X, O’Reilly ÉJ, Schwarzschild MA, Ascherio A.
Journal: Neurology. 2016 Jan 13.
PMID: 26764029

The researchers in this study looked at 90,214 participants who are involved in three ongoing US-based longitudinal studies (the Nurses’ Health Study (NHS), the Cancer Prevention Study II Nutrition (CPS-IIN), and the Health Professionals Follow-up Study (HPFS)). They identified 388 people in these cohorts who had developed Parkinson’s disease (202 men and 186 women) since their respective longitudinal studies began, and they matched them to 1,267 randomly selected control subjects.

Blood samples that had been taken from the Parkinson’s and control subjects were analysed, and the level of urate was measured. Normal levels of urate range from 3.5-7.2 milligrams per deciliter (mg/dL). The researchers found that there was no difference between in spectrum of urate levels in the women (with or without Parkinson’s).

In men, however, things were very different. The men with the lowest levels of urate had less than 4.9 mg/dL, while those with the highest levels had 6.3-9.0 mg/dL. Among the men with Parkinson’s disease, 45 had the highest level of urate and 58 had the lowest – if no difference existed, this number should be 50:50, but instead there is more than 30% difference. Men with high levels of urate had a lower chance of developing Parkinson’s disease.

The researchers then combined their results with the results from three previous studies on the same topic and found a very similar result. This led the researchers to conclude that men, but not women, with higher urate concentrations had a lower future risk of developing Parkinson’s, suggesting that urate could be protective against Parkinson’s risk or could slow disease progression during the preclinical stage of disease.

So, what is urate?

During the breaking down of dietary proteins, the liver produces large amounts of a chemical called ‘ammonia’. Ammonia is toxic for the body, so the liver breaks it down further, and one of the products of that process is urate. If the body does not get rid of it, urate can build up and form crystals within the joints. High blood concentrations of urate can lead to gout and is also associated with other medical conditions, such as diabetes and the formation of kidney stones.

Paradoxically, urate is also an ‘antioxidant’ – a chemical that prevents tissue from being damaged by the negative effects of oxygen (yes, we need oxygen but not too much). Other antioxidants include vitamin C, and vitamin E. It is this antioxidant function of urate that researchers believe has a positive effect in Parkinson’s disease.

What are the clinical trials we mentioned?

rfi-util-logo

In September 2015, a Phase III trial of Inosine was initiated. The study will involve 270 people with early-stage Parkinson’s. Inosine is a chemical precursor to urate and Phase III is the ‘acid test’ – a double blind test of treatment efficacy. A Michael J Fox Foundation-funded Phase II study showed that Inosine is safe and tolerable, and it also raised levels of urate in people with early-stage Parkinson’s disease. Now it is time to see if this raising of urate levels has a positive outcome. Enrollment for this trial is currently underway and -given the results of the study published this week – it will be interesting to see if there is a stronger effect in men in this phase III trial.


IMPORTANT EDITOR’S NOTE HERE: Inosine is commercially available as a dietary supplement, but we must stress that patients should act with caution. Inosine has not yet been proven as a therapy for Parkinson’s disease, and, as we indicated above, it can cause serious conditions such as gout and kidney stones. Please do not initiate usage of this chemical without first discussing it with your physician.

New Research -Shared genetic features

There was an interesting new study published yesterday:

Sanchez-Mut-Title

Title: Human DNA methylomes of neurodegenerative diseases show common epigenomic patterns.
Author: Sanchez-Mut JV, Heyn H, Vidal E, Moran S, Sayols S, Delgado-Morales R, Schultz MD, Ansoleaga B, Garcia-Esparcia P, Pons-Espinal M, de Lagran MM, Dopazo J, Rabano A, Avila J, Dierssen M, Lott I, Ferrer I, Ecker JR, Esteller M.
Journal: Transl Psychiatry. 2016 Jan 19;6:e718. doi: 10.1038/tp.2015.214.
PMID: 26784972 – this article is OPEN ACCESS if you would like to read it.

The researchers were curious to look for common genetic markers between the major neurodegenerative disease. It is often forgotten that the different neurodegenerative conditions, such as Alzheimer’s disease and Parkinson’s disease, share some common pathological features (the characteristic signs of the diseases in the brain).

For example, when you look at the brains of people with Alzheimer’s disease, approximately 50% of them will also have the alpha-synuclein-containing ‘Lewy bodies’ in their brains, which are more commonly associated with Parkinson’s disease. Likewise, Beta-amyloid plaques and neurotangles, which are characteristic features of Alzheimer’s disease are commonly found in Parkinson’s disease brains (click here and click here for more on this topic).

To find these shared genetic markers, the researcher extracted DNA from the prefrontal cortex (Brodmann area 9) of the brains of people with Alzheimer’s disease, dementia with Lewy bodies, Parkinson’s disease and Alzheimer-like neurodegenerative profile associated with Down’s syndrome samples (more than 75 percent of people with Down Syndrome aged 65 and older develop Alzheimer’s disease – click here for more on this).

Importantly, the researchers were looking at DNA methylation, which is a commonly used tool that allows a cell to fix genes in the “off” position. That is to say, the gene can not be activated. Thus the researchers were looking for regions of DNA that have to closed down.

They found that a very defined set of genes are turned off in these neurodegenerative disorders, suggesting that these condition might have similar underlying mechanisms or processes that subsequently develop into different clinical entities. These newly identified regions of DNA methylation will be further investigated with the goal that one day they may be used as biomarkers in diagnosis and also as potential new targets for the regenerative therapies.

Viruses and Parkinson’s – a hit and run story?

SupportGroup

I was recently presenting a talk at a Parkinson’s support group meeting. Afterwards I sat with some of the attendees and we chatted over tea and cookies. At one point the lady sitting beside me tapped me on the arm and said:

“The other day we were discussing some of the commonalities that we [people with Parkinson’s] share. I wonder if they would be of interest to you?”

“Absolutely”‘ I replied, “Let’s hear them”

“Well, firstly, most of us have little or any sense of smell” she said

And I nodded, “this is a common feature amongst people with Parkinson’s disease” (Click here for more on this)

“Ok. Number two, we all have trouble doing ‘number twos'”

I nodded again, and explained that constipation and gastrointestinal problems are also common features of Parkinson’s disease. (Click here for more on this)

“Interesting”, she said, before aiding: “Thirdly, none of us have ever had chickenpox”

I confess I looked at her a long time.

I was speechless.

I had never heard of anything like that.

In science, we are always looking for the presence of possible causal agents – not their absence. I was so intrigued that I took her contact details and told her that I would go away and do some homework on the matter.

I’d like to share my findings here as part of a larger discussion on viruses and Parkinson’s disease.


Given the random and indiscriminate way in which Parkinson’s disease attacks people, scientists have looked for a virus that may be causing the condition.

283615-virus

Throughout our lives, our immune system is constantly under attack from viruses. They are small infectious agent that thrive by replicating themselves inside the living cells of other organisms. Technically speaking they are not alive as they lack most of the machinery which characterizes ‘life’ (most importantly the components that is necessary for reproduction). We currently know of approx. 3000 viruses, but we can only guess at the total number of viruses (it may be in the millions!).

There are several different ways that Parkinson’s disease could theoretically be caused in some way by a virus:

1. There may be a specific virus that we are unaware of that infects the body at some point in one’s life causing the slow progressive disease. This could be consider the ‘lightning bolt’ theory – a single unlucky event with terrible consequences. Such a theory has weight as it would explain why some clusters of Parkinson’s disease is sometimes observed. People often use the example of Michael J Fox and his TV work colleagues in this theory.

 

leadership-fox-m-img_2

Actor Michael J Fox and three other people who worked on the Canadian TV show ‘Leo & me’ went on to develop Parkinson’s disease. Image source: Michael J Fox Foundation

2. A virus attacking the body coincides with a secondary event (e.g. a bacterial infection) that may result in the slow progressive events that result in Parkinson’s disease. The secondary event may be a genetic mutation or exposure to an environmental toxin. The virus attack in itself may not be enough in itself.

The two theories outlined above are just theories. We do not know if Parkinson’s disease is caused by a viral infection.

There is, however, some lines of evidence supporting the idea:

Influenza and Parkinson’s disease

Between January 1918 and December 1920 there were two outbreaks of an influenza virus during an event that became known as the 1918 flu pandemic. Approximately 500 million people across the globe were infected, and this resulted in 50 to 100 million deaths (basically 3-5% of the world’s population). Given that is occurred during World War 1, censors limited the media coverage of the pandemic in many countries in order to maintain morale. The Spanish media were not censored, however, and this is why the 1918 pandemic is often referred to as the ‘Spanish flu’.

Influenza is the virus that causes ‘the flu’. Most commonly in a mild form (runny nose, sore throat, coughing, and fatigue), the symptom will arise two days after exposure and last for about a week. There are three types of influenza viruses, called Type A, Type B, and Type C. Type A are the most virulent in humans. The influenza virus behind both of the outbreaks in the 1918 pandemic was a Type A. It was called H1N1.

NOTE: The “H” (hemagglutinin) and the “N” (neuraminidases) are both proteins that are found on the outer surface of the virus. Different viruses have different hemagglutinin and neuraminidase proteins, hence the numbering.

At the same time that H1N1 was causing havoc, a Romanian born neurologist named Constantin von Economo reported a number of unusual symptoms which were referred to as encephalitis lethargica (EL). This disease left many of the victims in a statue-like condition, both motionless and speechless. You may be familiar with the Oliver Sacks book ‘Awakenings’ which was turned into a film starring Robin Williams and Robert De Niro – the patients in that book were victims of EL.

robin_williams_con_robert_de_niro_en_1990

Robin Williams and Robert De Niro in Awakenings

Historically, it was believed that EL was caused by the influenza virus from the 1918 Spanish influenza pandemic. This was largely due to a temporal association and the finding of influenza antigens in some of the suffers of EL. More recent evidence rejects this hypothesis (e.g. an absence of viral RNA recovered from the brains of postencephalitic PD patients – click here for more on this). We genuinely don’t know what caused EL.

But there has recently been some evidence suggesting a link between Parkinson’s disease and influenza:

Jang-title

Title: Highly pathogenic H5N1 influenza virus can enter the central nervous system and induce neuroinflammation and neurodegeneration.
Author: Jang H, Boltz D, Sturm-Ramirez K, Shepherd KR, Jiao Y, Webster R, Smeyne RJ.
Journal: Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):14063-8.
PMID: 19667183

The researchers in this study found that when they injected the highly infectious H5N1 influenza virus into mice, the virus progressed from the periphery into the brain, where it induced Parkinson’s disease-like symptoms. The virus also caused a significant increase in the aggregation of the protein Alpha Synuclein. Importantly, they witnessed the loss of dopamine neurons in the midbrain of the mice 60 days after resolution of the infection.

This study supports the theory we discussed above (theory 1.) of a virus possibly causing Parkinson’s disease. These same researchers have also looked at other influenza viruses and found additional results:

Sadasivan-title

Title: Induction of microglia activation after infection with the non-neurotropic A/CA/04/2009 H1N1 influenza virus.
Author: Sadasivan S, Zanin M, O’Brien K, Schultz-Cherry S, Smeyne RJ.
Journal: PLoS One. 2015 Apr 10;10(4):e0124047.
PMID: 25861024

In this second study, however, the different type of influenza (H1N1) did not infect the brain, but did cause the immune system to flare up. This is an interesting example of the second theory we discussed above (theory 2.), the double hit theory of Parkinson’s disease, in which the virus doesn’t necessarily cause Parkinson’s disease but plays a supportive role to some other toxic agent in attacking the body.

In a follow up study to their 2009 report on H5N1, these same researchers found that the Parkinson’s disease-like symptoms that they observed were actually only temporary:

Jang-title2

Title: Inflammatory effects of highly pathogenic H5N1 influenza virus infection in the CNS of mice.
Authors: Jang H, Boltz D, McClaren J, Pani AK, Smeyne M, Korff A, Webster R, Smeyne RJ.
Journal: Journal for Neuroscience, 2012 Feb 1;32(5):1545-59.
PMID: 22302798

This third study may give further support to the double hit theory (theory 2.), but also indicates how complicated a viral component to Parkinson’s disease can be.

And influenza is not the only virus to be associated with Parkinson’s disease.

Hepatitis C and Parkinson’s disease

Hepatitis C is a contagious liver disease, which is caused by the hepatitis C virus (HCV). The virus has been found in the brains of infected people, and it has also been shown to kill dopamine neurons in cell culture. Only in the last few months, however, has a more direct association with Parkinson’s disease been proposed:

HepC-Title

Title: Hepatitis C virus infection as a risk factor for Parkinson disease: A nationwide cohort study.
Authors: Tsai HH, Liou HH, Muo CH, Lee CZ, Yen RF, Kao CH.
Journal: Neurology, 2015 Dec 23. Published early online.
PMID: 26701382

The researchers in this study wanted to investigate whether hepatitis C could be a risk factor for Parkinson’s disease. They did this by analyzing data from 2000-2010 drawn from the Taiwan National Health Insurance Research Database.

The database included 49,967 people with either hepatitis B, hepatitis C or both, in addition to 199,868 people without hepatitis. During the 12 year period, 270 participants who had a history of hepatitis developed Parkinson’s disease (120 still had hepatitis C). This compared with 1,060 participants who were free of hepatitis, but went on to develop Parkinson’s disease.

When the researchers controlled for potentially confounding factors (such as age, sex, etc), the researchers found participants with hepatitis C had a 30% greater risk of developing Parkinson’s disease than the controls.

Summary

It is tempting to consider a viral theory for Parkinson’s disease, especially as the condition seems to strike indiscriminately from out of the blue. Maybe a virus works in cahoots with another factor (unable to do the job alone). The evidence of this, however, has not been apparent to allow for a definitive conclusion.


Finally, regarding my homework… 

Never having Chickenpox could mean two different things – never being exposed to it OR being exposed to it and not getting infected (missing a particular protein required for infection). The first would suggest that exposure to the virus would given some kind of resistance to Parkinson’s disease. The latter would suggest that a protein which makes you vulnerable to Chickenpox gives you resistance to Parkinson’s disease.

As to the scientific literature, there have been two studies published regarding Chickenpox and Parkinson’s disease. The first:

Semchuk-title

Title: Parkinson’s disease: a test of the multifactorial etiologic hypothesis.
Authors: Semchuk KM, Love EJ, Lee RG.
Journal: Neurology, 1993 Jun;43(6):1173-80.
PMID: 8170564

In this study, the researchers collected life-time information (family history, occupational and medical records, etc) from 130 people with Parkinson’s disease. When the looked at all of the variables, they noted that a family history of Parkinson’s had the strongest association with Parkinson’s disease. This was followed by head trauma and occupational herbicide use. The subjects with Parkinson’s disease did not differ from control subjects with regards to:

  • exposure to smoking or ionizing radiation
  • family history of essential tremor
  • work-related contact with aluminum, carbon monoxide, cyanide, manganese, mercury, or mineral oils
  • history of arteriosclerosis, chicken pox, encephalitis, hypertension, hypotension, measles, mumps, rubella, or Spanish flu.

They proposed that the results supported the idea of a multifaceted cause of Parkinson’s disease, “probably involving genetic, environmental, trauma, and possibly other factors”.

And the second published study was:

Title: Infections as a risk factor for Parkinson’s disease: a case-control study.
Authors: Vlajinac H, Dzoljic E, Maksimovic J, Marinkovic J, Sipetic S, Kostic V.
Journal: Int J Neurosci. 2013 May;123(5):329-32. doi: 10.3109/00207454.2012.760560. Epub 2013 Feb 4.
PMID: 23270425

In this study the researchers found that Parkinson’s Disease was significantly associated to mumps, scarlet fever, influenza, whooping cough and herpes simplex infections. But they found no association between Parkinson’s disease and Tuberculosis, measles or chickenpox

So it would appear that chickenpox is not associated with Parkinson’s disease. And at a subsequent Parkinson’s support group meeting I asked the audience for a raise of hands as to who has had chickenpox and there was a sea of hands.

Back to the drawing board I guess.

 

The Placebo effect and Parkinson’s disease

According to our friends at Wikipedia:

A placebo (/pləˈsiboʊ/ plə-see-boh; Latin placēbō, “I shall please” from placeō, “I please”) is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient. Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect or placebo response.


power-of-placebo-effect

In our previous post we wrote about cell transplantation and we cited the two double-blind clinical studies that found little positive effect resulting from the procedure.

In both of those studies, half the participants were given a sham surgery – that is, they were put into the surgery room, anesthetized, an incision was made in their scalps, but nothing was injected into their brains. They (and their assessing investigators) were not told if they were in the transplant group or the sham/control group and they were left in this ‘blind’ state for 12-18 months.

Time is a funny thing.

After a couple of weeks of wondering which group they were in and self assessing their abilities since the surgery, some of the individuals in those studies may have started to think that you are in one group or the other. This is a very human thing to do.

The effect is VERY strong. And it can mess with a clinical study in terrible ways.

In one of the double-blind clinical studies discussed in the last post (Freed et at, 2001), one of the patients had described herself as ‘not being physically active for several years’ before her surgery. Shortly after her surgery, she found that she was able to hike and ice skate again. A miraculous change in situations.

Twelve months after the surgery, however, she found out that she’d had been in the sham/control surgery group. Nothing had been injected into her brain. She had received NO treatment.

Her response was solely due to the placebo effect.

The Placebo effect in Parkinson’s disease

Early last year there was an interesting study conducted that looked at the placebo effect and Parkinson’s disease.

Placebo1

Title: Placebo effect of medication cost in Parkinson disease: a randomized double-blind study.
Author: Espay AJ, Norris MM, Eliassen JC, Dwivedi A, Smith MS, Banks C, Allendorfer JB, Lang AE, Fleck DE, Linke MJ, Szaflarski JP.
Journal: Neurology. 2015 Feb 24;84(8):794-802.
PMID: 25632091

The investigators conducted a double-blind study involving 12 patients with moderate-severe Parkinson disease (average age of the subjects was 62.4 ± 7.9 years; and their average time since diagnosis was 11 ± 6 years). The study involved two visits to the clinic – the first visit involved a clinical assessment while the subjects were both ‘off’ and ‘on’ their standard medication. The assessment also involved a brain scan (fMRI). This was done to determine the magnitude of the dopaminergic benefit of their standard medication.
During the second visit, the subjects were told that they would be given two formulations – a “cheap” and “expensive” – of a “novel injectable dopamine agonist”. Both of these solutions were simply the same saline (medical salt water) solution. Four hours after being give the first injection, the subjects were given the other solution. In this manner, the subjects were exposed to both the ‘cheap’ and ‘expensive’ solutions. During visit 2, the subjects were clinically assessed and brain scanned 3 times, once before the first solution was injected, once after the first solution, and once after the second solution was given.

Below is a flowchart illustrating the structure study:

NEUROLOGY2014583914FF1

Source: Neurology

The results were interesting:

  • Both of the placebos improved motor function when compared with the baseline (no medication state)
  • The expensive placebo had more effect than the cheap placebo (remember: they were the same solution!)
  • The benefits were greater when patients were randomized first to expensive placebo followed by the cheap.
  • There was a significant difference in the level of improvement between the cheap and expensive placebos (UPDRS-III), with the expensive placebo giving better benefits
  • Brain imaging demonstrated that activation was greater when the cheap placebo was given first.

The authors concluded that the “expensive placebo significantly improved motor function and decreased brain activation in a direction and magnitude comparable to, albeit less than, levodopa. Perceptions of cost are capable of altering the placebo response in clinical studies“.

The authors also wrote a summary of the debriefing that followed the study, where the subjects were informed about the true nature of the study. They told the subjects that rather than being injected with a novel dopamine agonist, they were simply given a saline solution – the same solution for both ‘cheap’ and ‘expensive’. They reported that “responses ranged from disbelief to amazement regarding changes experienced“. It must have been rather bewildering to have been told that the positive benefits you experienced were ‘all in your head’ and not based on any pharmacological effect.

While extremely unethical, we here at the SoPD can’t help but wonder about long this placebo effect could last. Would the difference between the cheap and expensive solutions still exist in 12 months time if the subjects were left blinded and continued to take them?

So how might this work?
We know that the placebo effect in Parkinson’s disease is controlled by the release of dopamine – one of the chemicals in the brain that is affected by Parkinson’s disease. Importantly, we know that it the endogenous dopamine that is causing the effect – that is the dopamine our brains are producing naturally as opposed to the L-dopa treatment.

The dopamine that helps to control our motor movements is also involved with positive anticipation, motivation, and response to novelty. Thus when the placebo solution was given to subjects in this study, they believed that they were receiving an active drug and demonstrated an “expectation of reward” response. And the more expensive solution simply heightened the expectation and positive anticipation, therefore increasing the amount of dopamine produced/released.

Given that dopamine is involved with both the features of Parkinson’s disease AND with the mechanisms of anticipation/expectation, you can begin to understand why the placebo effect is such an enormous problem for clinicians undertaking clinical trials.

It would be nice, however, to have a better understanding of the placebo effect and try to harness its positive benefits while also treating Parkinson’s with diseasing slowing/halting therapies.

Cell transplantation – Replacing what has been lost

Parkinson’s disease is a neurodegenerative condition. That means that cells in the brain (neurons) are dying. By the time the motor features of Parkinson’s disease (rigidity, slowness of movement, and a resting tremor or shaking of a limb) become apparent to an individual, they will have lost 60-70% of the dopamine neurons in a region of the brain called the midbrain.

CD-Pathology-Parkinson'sDisease Chptr19-Fig 19-3 Parkinson DiseaseGrossMidbrain copy

Above are slices of human brain, taken from the midbrain of a healthy control subject (left) and an individual who died with Parkinson’s disease. The dopamine cells in the control subject can be seen on both sides of the brain with the eye because they produce a chemical (neuromelanin) that makes them black. These cells are noticeably absent in the Parkinsonian brain. Source: Springer

While there is a lot of research investigating how to stop or slow down the disease, at present, the only realistic way to deal with what has already been lost is to replace it. This could be done with cell transplantation.

Cell transplantation has had a long and colourful history of trial and error with regards to Parkinson’s disease. Importantly, given that there is currently no clinically approved cell transplantation procedure for Parkinson’s disease, the approach must be considered experimental, at best. This has not, however, stop numerous unscrupulous practitioners from advertising their services and preying on desperate individuals. They offer expensive operations, that have little if any peer-reviewed scientific evidence backing them.

Let us repeat: there is currently NO clinically approved cell transplantation procedure for Parkinson’s disease.


The history of cell transplantation in Parkinson’s disease

There has been an enormous amount of cell transplant work conducted in rodent models of Parkinson’s disease – in which the dopamine system is lesioned unilaterally. Many different types of cells have been used, but by far the most successful have been immature dopamine neurons (collected from embryos). The success of that work resulted in numerous clinical trials in the 1990s. Those trials began with a group in Lund (Sweden) who, in 1991, transplanted fetal midbrain tissue into six patients: four with advanced idiopathic Parkinson’s disease and two from the ‘Frozen addicts’ cohort (see the book “The case of the frozen addicts” for an explanation of these two individuals). Similar programmes had been initiated in England, Spain, Mexico, Cuba, France, and Belgium. These were all considered to be relatively successful, except for the fact that they were all open-label/not blinded studies, meaning that everyone involved in the study knew who was getting transplanted.

In the USA, these developments took place amid a major debates about the ban on federal funding for fetal tissue research that had been introduced by the Reagan administration in 1988. The Clinton administration lifted this ban in January, 1993, and this reversal opened the way for the National Institutes of Health (NIH) to provide funding for the two placebo-controlled studies. Those two trials were:

Trial no. 1: The Colorado/Columbia Trial:

A double blind trial in which 40 subjects (with advanced PD) received transplants of fetal midbrain tissue and 34 additional subjects (with advanced PD) had a sham surgery and were considered controls. Critically, neither the subjects nor the practitioners knew who was in which group. No patients in either arm of the study received immunosuppression, meaning that their immune systems were free to attack the injected cells (which would have been considered foreign by the body). The patients were followed up for 1 year after surgery and the success of the trial was judged on the basis of a self-report rating of clinical improvement or deterioration, scored by patients in their own homes and then sent to the investigator. The report of the study was published in the New England Journal of Medicine:

Title: Transplantation of embryonic dopamine neurons for severe Parkinson’s disease.
Authors: Freed CR, Greene PE, Breeze RE, Tsai WY, DuMouchel W, Kao R, Dillon S, Winfield H, Culver S, Trojanowski JQ, Eidelberg D, Fahn S.
Journal: New England Journal of Medicine 2001 Mar 8;344(10):710-9.
PMID: 11236774

Trial no. 2: The Tampa Bay Trial:

34 patients were randomly assigned either to receive a transplant of fetal midbrain tissue or to undergo a sham surgery. All patients received 6 months of immunosuppression after surgery. The primary endpoint for this study was a significant difference between the groups at 24 months after surgery. The report of this study was published in the journal, Annals of Neurology:

Title: A double-blind controlled trial of bilateral fetal nigral transplantation in Parkinson’s disease.
Authors: Olanow CW, Goetz CG, Kordower JH, Stoessl AJ, Sossi V, Brin MF, Shannon KM, Nauert GM, Perl DP, Godbold J, Freeman TB.
Journal: Ann Neurol. 2003 Sep;54(3):403-14.
PMID: 12953276

Both of these clinical studies failed to show any significant improvement at their endpoints. In addition, 15% – 50% of transplanted subjects developed what are called ‘graft induced dyskinesias’ (or GID’s). This is where the subjects display uncontrollable/erratic movement. Interestingly, patients under 60 years of age did show signs of improvement on when assessed both clinically (using the UPDRS-III) and when assessed using brain imaging techniques (increased F-dopa uptake on PET). But the overall negative results left a shadow over the technique for the better part of a decade.

So what is currently happening?

There are new clinical trials currently underway for cell transplantation in Parkinson’s disease. Primary amongst these is the Transeuro being conducted in Europe.

Transeuro_Logo_100

The Transeuro trial. Source: Transeuro

The Transeuro trial is an open label study, involving 40 subjects, transplanted in sites across Europe. They will receive immunosuppression for at least 12 months post surgery, and the end point of the study will be 3 years post surgery, and based on brain imaging of dopamine release from the transplanted cells (PET scans). Based on the previous double blind studies discussed above, only subject under 65 years of age have been enrolled in the study.

transeuro

The European consortium behind the Transeuro trial. Source: Transeuro

Do the transplants slow down the disease?

The evidence thus far is not clear, but some of the original patients from the 1991 Sweden trial were able to stop/cut back on their L-dopa treatment. Recently, some of the patients who received transplants have pass away and their brains have been examined post-mortem. One very interesting finding is that some of the cells in the transplants (1-5%) have lewy bodies in them. This suggests that the disease is passed on to the healthy transplanted cells in some way.

gr3

Above are 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

For more information on this, see these articles:

Title: Lewy bodies in grafted neurons in subjects with Parkinson’s disease suggest host-to-graft disease propagation.
Authors: Li JY, Englund E, Holton JL, Soulet D, Hagell P, Lees AJ, Lashley T, Quinn NP, Rehncrona S, Björklund A, Widner H, Revesz T, Lindvall O, Brundin P.
Journal: Nature Medicine. 2008 May;14(5):501-3.
PMID: 18391963

Title: Lewy body pathology in long-term fetal nigral transplants: is Parkinson’s disease transmitted from one neural system to another?
Authors: Kordower JH, Brundin P.
Journal: Neuropsychopharmacology. 2009;3 (1):254.
PMID: 19079079 (this review article is freely available)

Thus it would appear that cell transplantation will not stop the disease. At best it will simply allow us to replace the lost cells and reverse some of the motor related features of the condition. Ideally, this approach would be conducted in concert with additional therapies that slow or halt the disease (such as a vaccine possibly).

What next for cell transplantation?

Given the moral and ethical issues surrounding the use of fetal tissue, research has shifted towards using embryonic stem (ES) cells and turning them into midbrain dopamine neurons. And the results here have been very promising, with recent reports suggesting that ES cells can be converted into dopamine neurons and transplanted into rodent models of Parkinson’s disease with equal efficiency to that of fetal midbrain tissue.

Grelish-title

Title: Human ESC-derived dopamine neurons show similar preclinical efficacy and potency to fetal neurons when grafted in a rat model of Parkinson’s disease.
Authors: Grealish S, Diguet E, Kirkeby A, Mattsson B, Heuer A, Bramoulle Y, Van Camp N, Perrier AL, Hantraye P, Björklund A, Parmar M.
Journal: Cell Stem Cell. 2014 Nov 6;15(5):653-65.
PMID: 25517469

The take home message regarding cell transplantation is that at present it represents one of the only ways to replace what has been lost, but as of yet there is not an approved protocol for this approach in humans. As we said above, at best this should be considered experimental, and individuals selling expensive procedures should be avoided. The future looks very bright for this field, however, and we will keep you updated as more information comes to hand.


EDITORIAL NOTE: Happy new year everyone! We look forward to bringing you all the exciting news related to the science of Parkinson’s disease in 2016.