In Silicon valley (California), everyone is always looking for the “next killer app” – the piece of software (or application) that is going to change the world. The revolutionary next step that will solve all of our problems.
The title of today’s post is a play on the words ‘killer app’, but the ‘app’ part doesn’t refer to the word application. Rather it relates to the Alzheimer’s disease-related protein Amyloid Precursor Protein (or APP). Recently new research has been published suggesting that APP is interacting with a Parkinson’s disease-related protein called Leucine-rich repeat kinase 2 (or LRRK2).
The outcome of that interaction can have negative consequences though.
In today’s post we will discuss what is known about both proteins, what the new research suggests and what it could mean for Parkinson’s disease.
Seattle. Source: Thousandwonders
In the mid 1980’s James Leverenz and Mark Sumi of the University of Washington School of Medicine (Seattle) made a curious observation.
After noting the high number of people with Alzheimer’s disease that often displayed some of the clinical features of Parkinson’s disease, they decided to examined the postmortem brains of 40 people who had passed away with pathologically confirmed Alzheimer’s disease – that is, an analysis of their brains confirmed that they had Alzheimer’s.
What the two researchers found shocked them:
Title: Parkinson’s disease in patients with Alzheimer’s disease.
Authors: Leverenz J, Sumi SM.
Journal: Arch Neurol. 1986 Jul;43(7):662-4.
Of the 40 Alzheimer’s disease brains that they looked at nearly half of them (18 cases) had either dopamine cell loss or Lewy bodies – the characteristic features of Parkinsonian brain – in a region called the substantia nigra (where the dopamine neurons are located). They next went back and reviewed the clinical records of these cases and found that rigidity, with or without tremor, had been reported in 13 of those patients. According to their analysis 11 of those patients had the pathologic changes that warranted a diagnosis of Parkinson’s disease.
And the most surprising aspect of this research report: Almost all of the follow up studies, conducted by independent investigators found exactly the same thing!
It is now generally agreed by neuropathologists (the folks who analyse sections of brain for a living) that 20% to 50% of cases of Alzheimer’s disease have the characteristic round, cellular inclusions that we call Lewy bodies which are typically associated with Parkinson disease. In fact, in one analysis of 145 Alzheimer’s brains, 88 (that is 60%!) had chemically verified Lewy bodies (Click here to read more about that study).
A lewy body (brown with a black arrow) inside a cell. Source: Cure Dementia
Oh, and if you are wondering whether this is just a one way street, the answer is “No sir, this phenomenon works both ways”: the features of the Alzheimer’s brain (such as the clustering of a protein called beta-amyloid) are also found in many cases of pathologically confirmed Parkinson’s disease (Click here and here to read more about this).
So what are you saying? Alzheimer’s and Parkinson’s disease are the same thing???
In October 2015, researchers from Georgetown University announced the results of a small clinical trial that got the Parkinson’s community very excited. The study involved a cancer drug called Nilotinib, and the results were rather spectacular.
What happened next, however, was a bizarre sequence of disagreements over exactly what should happen next and who should be taking the drug forward. This caused delays to subsequent clinical trials and confusion for the entire Parkinson’s community who were so keenly awaiting fresh news about the drug.
Earlier this year, Georgetown University announced their own follow up phase II clinical trial and this week a second phase II clinical trial funded by a group led by the Michael J Fox foundation was initiated.
In todays post we will look at what Nilotinib is, how it apparently works for Parkinson’s disease, what is planned with the new trial, and how it differs from the ongoing Georgetown Phase II trial.
The FDA. Source: Vaporb2b
This week the U.S. Food and Drug Administration (FDA) has given approval for a multi-centre, double-blind, randomised, placebo-controlled Phase IIa clinical trial to be conducted, testing the safety and tolerability of Nilotinib (Tasigna) in Parkinson’s disease.
This is exciting and welcomed news.
What is Nilotinib?
Nilotinib (pronounced ‘nil-ot-in-ib’ and also known by its brand name Tasigna) is a small-molecule tyrosine kinase inhibitor, that has been approved for the treatment of imatinib-resistant chronic myelogenous leukemia (CML).
What does any that mean?
Basically, it is the drug that is used to treat a type of blood cancer (leukemia) when the other drugs have failed. It was approved for treating this cancer by the FDA in 2007.
People with high socioeconomic status jobs are believed to be better off in life.
New research published last week by the Centre for Disease Control, however, suggests that this may not be the case with regards to one’s risk of developing Parkinson’s disease.
In today’s post we will review the research and discuss what it means for our understanding of Parkinson’s disease.
The impact of socioeconomic status. Source: Medicalxpress
In 2013, a group of researchers at Carnegie Mellon University found a rather astonishing but very interesting association:
Children from lower socioeconomic status have shorter telomeres as adults.
Yeah, wow, strange… sorry, but what are telomeres?
Do you remember how all of your DNA is wound up tightly into 23 pairs of chromosomes? Well, telomeres are at the very ends of each of those chromosomes. They are literally the cap on each end. The name is derived from the Greek words ‘telos‘ meaning “end”, and ‘merοs‘ meaning “part”.
Telomeres are regions of repetitive nucleotide sequences (think the As, Gs, Ts, & Cs that make up your DNA) at each end of a chromosome. Their purpose seems to involve protecting the end of each chromosome from deteriorating or fusing with neighbouring chromosomes. Researchers also use their length is a marker of ageing because every time a cell divides, the telomeres on each chromosome gradually get shorter.
The clustering of a protein called alpha synuclein is one of the cardinal features of the brain of a person with Parkinson’s disease.
Recently published research has demonstrated that tiny antibodies (called nanobodies) derived from llamas (yes, llamas) are very effective at reducing this clustering of alpha synuclein in cell culture models of Parkinson’s disease.
In today’s post, we will discuss the science, review the research and consider what it could all mean for Parkinson’s disease.
Llama. Source: Imagesanimals
Ok, I confess: This post has been partly written purely because I really like llamas. And I’m not ashamed to admit it either.
I mean, look at them! They are fantastic:
Very cute. But what does this have to do with Parkinson’s disease?
Indeed. Let’s get down to business.
This post has also been written because llamas have a very interesting biological characteristic that is now being exploited in many areas of medical research, including for Parkinson’s disease.
For many people diagnosed with Parkinson’s disease, one of the scariest prospects of the condition that they face is the possibility of developing dyskinesias.
Dyskinesias are involuntary movements that can develop after long term use of the primary treatment of Parkinson’s disease: Levodopa
In todays post I discuss one experimental strategy for dealing with this debilitating aspect of Parkinson’s disease.
Dyskinesia. Source: JAMA Neurology
There is a normal course of events with Parkinson’s disease (and yes, I am grossly generalising here).
First comes the shock of the diagnosis.
This is generally followed by the roller coaster of various emotions (including disbelief, sadness, anger, denial).
Then comes the period during which one will try to familiarise oneself with the condition (reading books, searching online, joining Facebook groups), and this usually leads to awareness of some of the realities of the condition.
One of those realities (especially for people with early onset Parkinson’s disease) are dyskinesias.
What are dyskinesias?
Dyskinesias (from Greek: dys – abnormal; and kinēsis – motion, movement) are simply a category of movement disorders that are characterised by involuntary muscle movements. And they are certainly not specific to Parkinson’s disease.
As I have suggested in the summary at the top, they are associated in Parkinson’s disease with long-term use of Levodopa (also known as Sinemet or Madopar).
Sinemet is Levodopa. Source: Drugs
A new research report looking at the use of cholesterol-reducing drugs and the risk of developing Parkinson’s disease has just been published in the scientific journal Movement disorders.
The results of that study have led to some pretty startling headlines in the media, which have subsequently led to some pretty startled people who are currently taking the medication called statins.
In todays post, we will look at what statins are, what the study found, and discuss what it means for our understanding of Parkinson’s disease.
Cholesterol forming plaques (yellow) in the lining of arteries. Source: Healthguru
Cholesterol gets a lot of bad press.
Whether it’s high and low, the perfect balance of cholesterol in our blood seems to be critical to our overall health and sense of wellbeing. At least that is what we are constantly being told this by media and medical professionals alike.
But ask yourself this: Why? What exactly is cholesterol?
Good question. What is cholesterol?
Cholesterol (from the Greek ‘chole‘- bile and ‘stereos‘ – solid) is a waxy substance that is circulating our bodies. It is generated by the liver, but it is also found in many foods that we eat (for example, meats and egg yolks).
The chemical structure of Cholesterol. Source: Wikipedia
Cholesterol falls into one of three major classes of lipids – those three classes of lipids being Triglycerides, Phospholipids and Steroids (cholesterol is a steroid). Lipids are major components of the cell membranes and thus very important. Given that the name ‘lipids’ comes from the Greek lipos meaning fat, people often think of lipids simply as fats, but fats more accurately fall into just one class of lipids (Triglycerides).
Like many fats though, cholesterol dose not dissolve in water. As a result, it is transported within the blood system encased in a protein structure called a lipoprotein.
The structure of a lipoprotein; the purple C inside represents cholesterol. Source: Wikipedia
Lipoproteins have a very simple classification system based on their density:
- very low density lipoprotein (VLDL)
- low density lipoprotein (LDL)
- intermediate density lipoprotein (IDL)
- high density lipoprotein (HDL).
Now understand that all of these different types of lipoproteins contain cholesterol, but they are carrying it to different locations and this is why some of these are referred to as good and bad.
The first three types of lipoproteins carry newly synthesised cholesterol from the liver to various parts of the body, and thus too much of this activity would be bad as it results in an over supply of cholesterol clogging up different areas, such as the arteries.
LDLs, in particular, carry a lot of cholesterol (with approximately 50% of their contents being cholesterol, compared to only 20-30% in the other lipoproteins), and this is why LDLs are often referred to as ‘bad cholesterol’. High levels of LDLs can result in atherosclerosis (or the build-up of fatty material inside your arteries).
Progressive and painless, atherosclerosis develops as cholesterol silently and slowly accumulates in the wall of the artery, in clumps that are called plaques. White blood cells stream in to digest the LDL cholesterol, but over many years the toxic mess of cholesterol and cells becomes an ever enlarging plaque. If the plaque ever ruptures, it could cause clotting which would lead to a heart attack or stroke.
So yeah, some lipoproteins can be considered bad.
HDLs, on the other hand, collects cholesterol and other lipids from cells around the body and take them back to the liver. And this is why HDLs are sometimes referred to as “good cholesterol” because higher concentrations of HDLs are associated with lower rates of atherosclerosis progression (and hopefully regression).
But why is cholesterol important?
While cholesterol is usually associated with what is floating around in your bloodstream, it is also present (and very necessary) in every cell in your body. It helps to produce cell membranes, hormones, vitamin D, and the bile acids that help you digest fat.
It is particularly important for your brain, which contains approximately 25 percent of the cholesterol in your body. Numerous neurodegenerative conditions are associated with cholesterol disfunction (such as Alzheimer’s disease and Huntington’s disease – Click here for more on this). In addition, low levels of cholesterol is associated with violent behaviour (Click here to read more about this).
Are there any associations between cholesterol and Parkinson’s disease?
The associations between cholesterol and Parkinson’s disease is a topic of much debate. While there have been numerous studies investigating cholesterol levels in blood in people with Parkinson’s disease, the results have not been consistent (Click here for a good review on this topic).
Rather than looking at cholesterol directly, a lot of researchers have chosen to focus on the medication that is used to treat high levels of cholesterol – a class of drugs called statins.
Title: Prospective study of statin use and risk of Parkinson disease.
Authors: Gao X, Simon KC, Schwarzschild MA, Ascherio A.
Journal: Arch Neurol. 2012 Mar;69(3):380-4.
PMID: 22410446 (This article is OPEN ACCESS if you would like to read it)
In this study the researchers conduced a prospective study involving the medical details of 38 192 men and 90 874 women from two huge US databases: the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS).
NHS study was started in 1976 when 121,700 female registered nurses (aged 30 to 55 years) completed a mailed questionnaire. They provided an overview of their medical histories and health-related behaviours. The HPFS study was established in 1986, when 51,529 male health professionals (40 to 75 years) responded to a similar questionnaire. Both the NHS and the HPFS send out follow-up questionnaires every 2 years.
By analysing all of that data, the investigators found 644 cases of Parkinson’s disease (338 women and 306 men). They noticed that the risk of Parkinson’s disease was approximately 25% lower among people currently taking statins when compared to people not using statins. And this association was significant in statin users younger than 60 years of age (P = 0.02).
What are statins?
Also known as HMG-CoA reductase inhibitors, statins are a class of drug that inhibits/blocks an enzyme called 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase.
HMG-CoA reductase is the key enzyme regulating the production of cholesterol from mevalonic acid in the liver. By blocking this process statins help lower the total amount of cholesterol available in your bloodstream.
Statins are used to treat hypercholesterolemia (also called dyslipidemia) which is high levels of cholesterol in the blood. And they are one of the most widely prescribed classes of drugs currently available, with approximately 23 percent of adults in the US report using statin medications (Source).
Now, while the study above found an interesting association between statin use and a lower risk of Parkinson’s disease, the other research published on this topic has not been very consistent. In fact, a review in 2009 found a significant associations between statin use and lower risk of Parkinson’s disease was observed in only two out of five prospective studies (Click here to see that review).
New research published this week has attempted to clear up some of that inconsistency, by starting with a huge dataset and digging deep into the numbers.
So what new research has been published?
Title: Statins may facilitate Parkinson’s disease: Insight gained from a large, national claims database
Authors: Liu GD, Sterling NW, Kong L, Lewis MM, Mailman RB, Chen H, Leslie D, Huang X
Journal: Movement Disorder, 2017 Jun;32(6):913-917.
Using the MarketScan Commercial Claims and Encounters database which catalogues the healthcare use and medical expenditures of more than 50 million employees and their family members each year, the researcher behind that study identified 30,343,035 individuals that fit their initial criteria (that being “all individuals in the database who had 1 year or more of continuous enrolment during January 1, 2008, to December 31, 2012, and were 40 years of age or older at any time during their enrolment”). From this group, the researcher found a total of 21,599 individuals who had been diagnosed with Parkinson’s disease.
In their initial analysis, the researchers found that Parkinson’s disease was positively associated with age, male gender, hypertension, coronary artery disease, and usage of cholesterol-lowering drugs (both statins and non-statins). The condition was negatively associated with hyperlipidemia (or high levels of cholesterol). This result suggests not only that people with higher levels of cholesterol have a reduced chance of developing Parkinson’s disease, but taking medication to lower cholesterol levels may actually increase ones risk of developing the condition.
One interesting finding in the data was the effect that different types of statins had on the association.
Statins can be classified into two basic groups: water soluble (or hydrophilic) and lipid soluble (or lipophilic) statins. Hydrophilic molecule have more favourable interactions with water than with oil, and vice versa for lipophilic molecules.
Hydrophilic vs lipophilic molecules. Source: Riken
Water soluble (Hydrophilic) statins include statins such as pravastatin and rosuvastatin; while all other available statins (eg. atorvastatin, cerivastatin, fluvastatin, lovastatin and simvastatin) are lipophilic.
In this new study, the researchers found that the association between statin use and increased risk of developing Parkinson’s disease was more pronounced for lipophilic statins (a statistically significant 58% increase – P < 0.0001), compared to hydrophilic statins (a non-significant 19% increase – P = 0.25). One possible explanation for this difference is that lipophilic statins (like simvastatin and atorvastatin) cross the blood-brain barrier more easily and may have more effect on the brain than hydrophilic ones.
The investigators also found that this association was most robust during the initial phase of statin treatment. That is to say, the researchers observed a 82% in risk of PD within 1 year of having started statin treatment, and only a 37% increase five years after starting statin treatment.; P < 0.0001). Given this finding, the investigators questioned whether statins may be playing a facilitatory role in the development of Parkinson’s disease – for example, statins may be “unmasking” the condition during its earliest stages.
So statins are bad then?
Can I answer this question with a diplomatic “I don’t know”?
It is difficult to really answer that question based on the results of just this one study. This is mostly because this new finding is in complete contrast to a lot of experimental research over the last few years which has shown statins to be neuroprotective in many models of Parkinson’s disease. Studies such as this one:
Title: Simvastatin inhibits the activation of p21ras and prevents the loss of dopaminergic neurons in a mouse model of Parkinson’s disease.
Authors: Ghosh A, Roy A, Matras J, Brahmachari S, Gendelman HE, Pahan K.
Journal: J Neurosci. 2009 Oct 28;29(43):13543-56.
PMID: 19864567 (This study is OPEN ACCESS if you would like to read it)
In this study, the researchers found that two statins (pravastatin and simvastatin – one hydrophilic and one lipophilic, respectively) both exhibited the ability to suppress the response of helper cells in the brain (called microglial) in a neurotoxin model of Parkinson’s disease. This microglial suppression resulted in a significant neuroprotective effect on the dopamine neurons in these animals.
Another study found more Parkinson’s disease relevant effects from statin treatment:
TItle: Lovastatin ameliorates alpha-synuclein accumulation and oxidation in transgenic mouse models of alpha-synucleinopathies.
Authors: Koob AO, Ubhi K, Paulsson JF, Kelly J, Rockenstein E, Mante M, Adame A, Masliah E.
Journal: Exp Neurol. 2010 Feb;221(2):267-74.
PMID: 19944097 (This study is OPEN ACCESS if you would like to read it)
In this study, the researchers treated two different types of genetically engineered mice (both sets of mice produce very high levels of alpha synuclein – the protein closely associated with Parkinson’s disease) with a statin called lovastatin. In both groups of alpha synuclein producing mice, lovastatin treatment resulted in significant reductions in the levels of cholesterol in their blood when compared to the saline-treated control mice. The treated mice also demonstrated a significant reduction in levels of alpha synuclein clustering (or aggregation) in the brain than untreated mice, and this reduction in alpha synuclein accumulation was associated with a lessening of pathological damage in the brain.
So statins may not be all bad?
One thing many of these studies fail to do is differentiate between whether statins are causing the trouble (or benefit) directly or whether simply lowering cholesterol levels is having a negative impact. That is to say, do statins actually do something else? Other than lowering cholesterol levels, are statins having additional activities that could cause good or bad things to happen?
The recently published study we are reviewing in this post suggested that non-statin cholesterol medication is also positively associated with developing Parkinson’s disease. Thus it may be that statins are not bad, but rather the lowering of cholesterol levels that is. This raises the question of whether high levels of cholesterol are delaying the onset of Parkinson’s disease, and one can only wonder what a cholesterol-based process might be able to tell us about the development of Parkinson’s disease.
If the findings of this latest study are convincingly replicated by other groups, however, we may need to reconsider the use of statins not in our day-to-day clinical practice. At the very least, we will need to predetermine which individuals may be more susceptible to developing Parkinson’s disease following the initiation of statin treatment. It would actually be very interesting to go back to the original data set of this new study and investigate what addition medical features were shared between the people that developed Parkinson’s disease after starting statin treatment. For example, were they all glucose intolerant? One would hope that the investigators are currently doing this.
Are Statins currently being tested in the clinic for Parkinson’s disease?
(Oh boy! Tough question) Yes, they are.
There is currently a nation wide study being conducted in the UK called PD STAT.
Is this dangerous given the results of the new research study?
(Oh boy! Even tougher question!)
Again, we are asking this question based on the results of one recent study. Replication with independent databases is required before definitive conclusions can be made.
There have, however, been previous clinical studies of statins in neurodegenerative conditions and these drugs have not exhibited any negative effects (that I am aware of). In fact, a clinical trial for multiple sclerosis published in 2014 indicated some positive results for sufferers taking simvastatin:
Title: Effect of high-dose simvastatin on brain atrophy and disability in secondary progressive multiple sclerosis (MS-STAT): a randomised, placebo-controlled, phase 2 trial.
Authors: Chataway J, Schuerer N, Alsanousi A, Chan D, MacManus D, Hunter K, Anderson V, Bangham CR, Clegg S, Nielsen C, Fox NC, Wilkie D, Nicholas JM, Calder VL, Greenwood J, Frost C, Nicholas R.
Journal: Lancet. 2014 Jun 28;383(9936):2213-21.
PMID: 24655729 (This article is OPEN ACCESS if you would like to read it)
In this double-blind clinical study (meaning that both the investigators and the subjects in the study were unaware of which treatment was being administered), 140 people with multiple sclerosis were randomly assigned to receive either the statin drug simvastatin (70 people; 40 mg per day for the first month and then 80 mg per day for the remainder of 18 months) or a placebo treatment (70 people).
Patients were seen at 1, 6, 12, and 24 months into the study, with telephone follow-up at months 3 and 18. MRI brain scans were also made at the start of the trial, and then again at 12 months and 25 months for comparative sake.
The results of the study indicate that high-dose simvastatin was well tolerated and reduced the rate of whole-brain shrinkage compared with the placebo treatment. The mean annualised shrinkage rate was significantly lower in patients in the simvastatin group. The researchers were very pleased with this result and are looking to conduct a larger phase III clinical trial.
Other studies have not demonstrated beneficial results from statin treatment, but they have also not observed a worsening of the disease conditions:
Title: A randomized, double-blind, placebo-controlled trial of simvastatin to treat Alzheimer disease.
Authors:Sano M, Bell KL, Galasko D, Galvin JE, Thomas RG, van Dyck CH, Aisen PS.
Journal: Neurology. 2011 Aug 9;77(6):556-63.
PMID: 21795660 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators recruited a total of 406 individuals were mild to moderate Alzheimer’s disease, and they were randomly assigned to two groups: 204 to simvastatin (20 mg/day, for 6 weeks then 40 mg per day for the remainder of 18 months) and 202 to placebo control treatment. While Simvastatin displayed no beneficial effects on the progression of symptoms in treated individuals with mild to moderate Alzheimer’s disease (other than significantly lowering of cholesterol levels), the treatment also exhibited no effect on worsening the disease.
So what does it all mean?
Research investigating cholesterol and its association with Parkinson’s disease has been going on for a long time. This week a research report involving a huge database was published which indicated that using cholesterol reducing medication could significantly increase one’s risk of developing Parkinson’s disease.
These results do not mean that someone being administered statins is automatically going to develop Parkinson’s disease, but – if the results are replicated – it may need to be something that physicians should consider before prescribing this class of drug.
Whether ongoing clinical trials of statins and Parkinson’s disease should be reconsidered is a subject for debate well above my pay grade (and only if the current results are replicated independently). It could be that statin treatment (or lowering of cholesterol) may have an ‘unmasking’ effect in some individuals, but does this mean that any beneficial effects in other individuals should be discounted? If preclinical data is correct, for example, statins may reduce alpha synuclein clustering in some people which could be beneficial in Parkinson’s.
As we have said above, further research is required in this area before definitive conclusions can be made. This is particularly important given the inconsistencies of the previous research results in the statin and Parkinson’s disease field of investigation.
EDITORIAL NOTE: The information provided by the SoPD website is for information and educational purposes only. Under no circumstances should it ever be considered medical or actionable advice. It is provided by research scientists, not medical practitioners. Any actions taken – based on what has been read on the website – are the sole responsibility of the reader. Any actions being contemplated by readers should firstly be discussed with a qualified healthcare professional who is aware of your medical history. While some of the information discussed in this post may cause concern, please speak with your medical physician before attempting any change in an existing treatment regime.
The banner for today’s post was sourced from HarvardHealth
Our apologies to anyone who is squeamish about needles, but this is generally how most people get their seasonal flu vaccination.
Why are we talking about flu vaccines?
Because new research, published last week, suggests everyone should be going out and getting them in the hope of reducing our risk of Parkinson’s disease.
In today’s post we will review the research, exactly what a flu vaccine is, and how it relates to Parkinson’s disease.
Electron micro photograph of Influenza viruses. Source: Neuro-hemin
Long time readers of the SoPD blog will know that I have a particular fascination with theories regarding a viral or microbial role in the development of Parkinson’s disease (the ‘idiopathic’ – or arising spontaneously – variety at least).
Numerous reasons. For example:
- The targeted nature of the condition (why are only selective groups of cells are lost in the brain during the early stages of the condition?)
- The unexplained protein aggregation (eg. Lewy bodies; could they be a cellular defensive mechanism against viruses/microbes – Click here to read more on this idea)
- The asymmetry of the onset (why do tremors start on only one side of the body in most cases?)
And we have previously discussed research here on the website regarding possible associations between Parkinson’s disease and and various types of viruses (including Hepatitis C, Herpes Simplex, and Influenza).
Today we re-visit influenza as new research has been published on this topic.
What is influenza?
Influenza is a single-stranded, RNA virus of the orthomyxovirus family of viruses.
A schematic of the influenza virus. Source: CDC
It is the virus that causes ‘the flu’ – (runny nose, sore throat, coughing, and fatigue) – with the symptom arising two days after exposure and lasting for about a week. In humans, 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.
Schematic of Influenza virus. Source: Bcm
As the image above indicates, the influenza virus has a rounded shape, with “HA” (hemagglutinin) and “NA” (neuraminidases) proteins on the outer surface of the virus. The HA protein allows the virus to stick to the outer membrane of a cell. The virus can then infect the host cell and start the process of reproduction – making more copies of itself. The NA protein is required for the virus to exit the host cell and go on to infect other cells. Different influenza viruses have different combinations of hemagglutinin and neuraminidase proteins, hence the numbering. For example, the Type A virus that caused the outbreaks in the 1918 pandemic was called H1N1.
Inside the influenza virus, there are there are eight pieces (segments) of RNA, hence the fact that influenza is an RNA virus. Some viruses have DNA while others have RNA. The 8 segments of RNA provide the information that is required for making new copies of the virus. Each of these segments provides the instructions for making one or more proteins of the virus (eg. segment 4 contains the instructions to make the HA protein).
The 8 segments of RNA in influenza. Source: URMC
The Influenza virus is one of the most changeable viruses we are aware of, which makes it such a tricky beast to deal with. Influenza uses two techniques to change over time. They are called shift and drift.
Shifting is an sudden change in the virus, which produces a completely new combination of the HA and NA proteins. Virus shift can take place when a person or animal is infected with two different subtypes of influenza. When new viral particles are generated inside the cell, there is a mix of both subtypes of virus which gives rise to an all new type of virus.
An example of viral shift. Source: Bcm
Drifting is the process of random genetic mutation. Gradual, continuous, spontaneous changes that occur when the virus makes small “mistakes” during the replication of its RNA. These mistakes can results in a slight difference in the HA or NA proteins, and although those changes are small, they can be significant enough that the human immune system will no longer recognise and attack the virus. This is why you can repeatedly get the flu and why flu vaccines must be administered each year to combat new forms of circulating influenza virus.
What is a flu jab exactly?
Seasonal flu vaccination is a treatment that is given each year to minimise the risk of being infected by an influenza virus.
The ‘seasonal’ part of the label refers to the fact that the flu vaccine changes each year. Most flu vaccines target three strains of the viruses (and are thus called ‘Trivalent flu vaccines’) which are selected each year based on data collected by various health organisations around the world.
The three chosen viruses for a particular year are traditionally injected into and grown in hens’ eggs, then harvested and purified before the viral particles are chemically deactivated. The three dead viruses are then pooled together and packaged as a vaccine. As you can see in the image below, the process of vaccine production is laborious and takes a full year:
The process of vaccine production. Source: Linkedin
By injecting people with the dead viruses from three different strains of the influenza virus, however, the immune system has the chance to build up a defence against those viruses without the risk of the individual becoming infected (the dead viruses in the vaccine can not infect cells).
Flu vaccines cause the immune system to produce antibodies which are used by the immune system to help defend the body against future attacks from viruses. These antibodies generally take about two weeks to develop in the body after vaccination.
As we have said most injected flu vaccines protect against three types of flu virus. Generally each of the three viruses is taken from the following strains:
- Influenza A (H1N1) – the strain of flu that caused the swine flu pandemic in 2009.
- Influenza A (H3N2) – a strain of flu that mainly affects the elderly and people at risk with long term health conditions. In 2016/17 the vaccine contains an A/Hong Kong/4801/2014 H3N2-like virus.
- Influenza B – a strain of flu that particularly affects children. In 2016/17 the vaccine contains B/Brisbane/60/2008-like virus.
How effective are the vaccines?
Well, it really depends on which strains of influenza are going to affect the most people each year, and this can vary greatly. Overall, however, research from the Centers for Disease Control and Prevention (or CDC) suggests that the seasonal flu vaccine reduces the chance of getting sick by approximately 50% (Source). Not bad when you think about it.
Ok, so are there actually any connections between influenza and Parkinson’s disease?
This question is up for debate.
There are certainly some tentative associations between influenza and Parkinson’s disease. Early on, those connections were coincidental, but more recently research is suggesting that there could be a closer relationship.
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 by the H1N1 influenza virus, 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’.
1918 Spanish flu. Source: Chronicle
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 victims in a statue-like condition, speechless and motionless.
Constantin von Economo. Source: Wikipedia
By 1926, EL had spread around the world, with nearly five million people being affected. Many of those who survived never returned to their pre-existing state of health. They were left frozen in an immobile state.
An individual with encephalitis lethargica. Source: Baillement
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 (things happening at approximately the same time) and the finding of influenza antigens in some of the suffers of EL (Click here to read more about this).
And then there were also the observations of Dr Oliver Sacks:
Amazing guy! Dr Oliver Sacks. Source: Pensologosou
During the late 1960s, while employed as a neurologist at Beth Abraham Hospital’s chronic-care facility in New York, Dr Sacks began working with a group of survivors of EL, who had been left immobile by the condition. He treated these individuals with L-dopa (the standard treatment for Parkinson’s disease now, but it was still experimental at the time) and he observed them become miraculously reanimated. The sufferers went from being completely motionless to suddenly active and mobile. Unfortunately the beneficial effects were very short lived.
You may be familiar with Dr Sack’s book about his experience of treating these patients. It is called ‘Awakenings’ and it was turned into a film starring actors Robin Williams and Robert De Niro.
Robin Williams and Robert De Niro in Awakenings. Source: Pinterest
More recent, postmortem analysis of the brains of EL patients found an absence of influenza RNA – click here for more on this), which has led many researchers to simply reject the association between influenza and EL. The evidence supporting this rejection, however, has also been questioned (click here to read more on this), leaving the question of an association between influenza and EL still open for debate.
I think it’s fair to say that we genuinely do not know what caused EL. Whether it was influenza or not is still be undecided.
Ok, so that was the coincidental evidence. Has there been a more direct connection between influenza and Parkinson’s disease?
This is Dr Richard J Smeyne:
He is a research faculty member in the Department of Developmental Neurobiology at St. Jude Children’s Research Hospital (Memphis, Tennessee).
He has had a strong interest in what role viruses like influenza could be playing in the development of Parkinson’s disease, and his research group has published several interesting research reports on this topic, including:
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 (This article is OPEN ACCESS if you would like to read it)
Dr Smeyne and his colleagues found in this study that when they injected the highly infectious A/Vietnam/1203/04 (H5N1) influenza virus into mice, the virus progressed from the periphery (outside the brain) into the brain itself, where it induced Parkinson’s disease-like symptoms.
The virus also caused a significant increase in the accumulation of the Parkinson’s disease-associated protein Alpha Synuclein. In addition, they witnessed the loss of dopamine neurons in the midbrain of the mice at 60 days after the infection – that cell loss resembling what is observed in the brains of people with Parkinson’s disease.
Naturally this got the researchers rather excited!
In a follow up study on H5N1, however, these same researchers found that the Parkinson’s disease-like symptoms that they observed were actually only temporary:
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 article is OPEN ACCESS if you would like to read it)
Dr Smeyne and colleagues repeated the 2009 study and had a closer look at what was happening to the dopamine neurons that were disappearing at 60 days post infection with the virus. When they looked at mice at 90 days post infection, they found that the number of dopamine neurons had returned to their normal number. This pattern was also observed in a region of the brain called the striatum, where the dopamine neurons release their dopamine. The levels of dopamine dropped soon after infection, but rose back to normal by 90 days post infection.
How does that work?
The results suggest that rather than developing new dopamine neurons in some kind of miraculous regenerative process, the dopamine neurons that were infected by the virus simply stopped producing dopamine while they dealt with the viral infection. Once the crisis was over, the dopamine neurons went back to life as normal. And because the researcher use chemicals in the production of dopamine to identify the dopamine neurons, they mistakenly thought that the cells had died when they couldn’t see those chemicals.
One interesting observation from the study was that H5N1 infection in mice induced a long-lasting inflammatory response in brain. The resident helper cells, called microglia, became activated by the infection, but remained active long after the dopamine neurons returned to normal service. The investigators speculated as to whether this activation may be a contributing factor in the development of neurodegenerative disorders.
And this is an interesting idea.
In a follow up study, they investigated this further by looking another influenza viruse that doesn’t actually infect cells in the brain:
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 (This article is OPEN ACCESS if you would like to read it)
In this study, a different type of influenza (H1N1) was tested, and while it did not infect the brain, it did cause the microglia cells to flare up and become activated. And again, this activation was sustained for a long period after the infection (at least 90 days).
This is a really interesting finding and relates to the idea of a “double hit” theory of Parkinson’s disease, in which the virus doesn’t necessarily cause Parkinson’s disease but may play a supplemental or distractionary role, grabbing the attention of the immune system while some other toxic agent is also attacking the body. Or perhaps simply weakening the immune system by forcing it to fight on multiple fronts. Alone the two would not cause as much damage, but in combination they could deal a terrible blow.
So what was the flu vaccine research published last week?
Again, from Dr Smeyne’s research group, this report looked whether the combination of an influenza virus infection plus a toxic agent gave a worse outcome than just the toxic agent by itself. An interesting idea for a study, but then the investigators threw in another component: what effect would a influenza vaccine have in such an experiment. And the results are interesting:
Title: Synergistic effects of influenza and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can be eliminated by the use of influenza therapeutics: experimental evidence for the multi-hit hypothesis
Authors: Sadasivan S, Sharp B, Schultz-Cherry S, & Smeyne RJ
Journal: npj Parkinson’s Disease 3, 18
PMID: N/A (This article is OPEN ACCESS if you would like to read it)
What the researchers found was that H1N1-infected mice that were treated with a neurotoxin (called MPTP – a toxin that specifically kills dopamine neurons) exhibit a 20% greater loss of dopamine neurons than mice that were treated with MPTP alone.
And this increase in dopamine neuron loss was completely eliminated by giving the mice the influenza vaccination. The researchers concluded that the results demonstrate that multiple insults (such as a viral infection and a toxin) can enhance the impact, and may even be significant in allowing an individual to cross a particular threshold for developing a disease.
It’s an intriguing idea.
Have epidemiologists (population data researchers) ever investigated a connection between Parkinson’s disease and influenza?
And yes they have:
Title: Parkinson’s disease or Parkinson symptoms following seasonal influenza.
Authors: Toovey S, Jick SS, Meier CR.
Journal: Influenza Other Respir Viruses. 2011 Sep;5(5):328-33.
PMID: 21668692 (This article is OPEN ACCESS if you would like to read it)
In this first study, the researcher used the UK‐based General Practice Research Database to perform a case–control analysis (that means they compare an affected population with an unaffected ‘control’ population. They identified individual cases who had developed an ‘incident diagnosis’ of Parkinson’s disease or Parkinson’s like symptoms between 1994 and March 2007. For each of those case files identified, they matched them with at least four age matched control case files for comparative sake.
Their analysis found that the risk of developing Parkinson’s disease was not associated with previous influenza infections. BUT, they did find that Influenza was associated with Parkinson’s‐like symptoms such as tremor, particularly in the month after an infection. One can’t help but wonder if the dopamine neurons stopped producing dopamine during that period while they dealt with the viral infection.
But of course, I’m only speculating here… and it’s not like there was a second study suggesting that there is actually an association between Parkinson’s disease and influenza.
A year after that first study, a second study was published:
Journal: Association of Parkinson’s disease with infections and occupational exposure to possible vectors.
Authors: Harris MA, Tsui JK, Marion SA, Shen H, Teschke K.
Journal: Movement Disorder. 2012 Aug;27(9):1111-7.
This second study reported that there is actually an association between Parkinson’s disease and influenza.
This investigation was also a case-control study, but it was based in British Columbia, Canada. The researchers recruited 403 individuals detected by their use of antiparkinsonian medications and matched them with 405 control subjects selected from the universal health insurance plan. Severe influenza was associated with Parkinson’s disease at an odds ratio of 2.01 (1 being no difference) and the range of the odds was 1.16-3.48. That’s pretty significant.
Interestingly, the effect is reduced when the reports of infection were restricted to those occurring within 10 years before diagnosis. This observation would suggest that early life infections may have more impact than previously thought.
Curiously, the researchers also found that exposure to certain animals (cats odds ration of 2.06; range 1.09-3.92) and cattle (2.23; range 1.22-4.09) was also associated with developing Parkinson’s disease.
Time to get rid of the pet cow.
Do any other neurodegenerative condition have associations with influenza?
In the limited literature search that we conducted, we only found reports dealing with influenza and Alzheimer’s disease.
Large studies suggest that Alzheimer’s is not associated with influenza (click here to read more on this). Interestingly, the Alzheimer’s associated protein beta amyloid has been shown to inhibit influenza A viruses (Click here to read that report), which may partly explain the lack of any association.
Influenza does have a mild association, however, with depression (Click here to see that report).
So what does it all mean?
A viral theory for Parkinson’s disease has existed since the great epidemic of 1918. Recent evidence points towards several viruses potentially having some involvement in the development of this neurodegenerative condition. And recent evidence suggests that influenza in particular could be particularly influential.
In 1938, Jonas Salk and Thomas Francis developed the first vaccine against flu viruses. It could be interesting for epidemiologists to go back and see if regular flu vaccination usage (if such data exists) reduces the risk of developing Parkinson’s disease.
But until such data is published, however, perhaps it would be wise to go and get a flu vaccine shot.
The banner for today’s post was sourced from the HuntingtonPost
We have been contacted by some readers asking about a new stem cell transplantation clinical trial for Parkinson’s disease about to start in China (see the Nature journal editorial regarding this new trial by clicking here).
While this is an exciting development, there have been some concerns raised in the research community regarding this trial.
In today’s post, we will discuss what is planned and what it will mean for stem cell transplantation research.
Brain surgery. Source Bionews-tx
Parkinson’s disease is a progressive neurodegenerative condition.
This means that cells in the brain are slowly being lost over time. What makes the condition particularly interesting is that certain types of brain cells are more affected than others. The classic example of this is the dopamine neurons in an area of the brain called the substantia nigra, which resides in the midbrain.
The number of dark pigmented dopamine cells in the substantia nigra are reduced in the Parkinson’s disease brain (right). Source: Adapted from Memorangapp
Approximately 50% of the dopamine neurons in the midbrain have been lost by the time a person is diagnosed with Parkinson’s disease (note the lack of dark colouration in the substantia nigra of the Parkinsonian brain in the image above), and as the condition progresses the motor features – associated with the loss of dopamine neurons – gradually get worse. This is why dopamine replacement treatments (like L-dopa) are used for controlling the motor symptoms of Parkinson’s disease.
A lot of research effort is being spent on finding disease slowing/halting treatments, but these will leave many people who have already been diagnosed with Parkinson’s disease still dealing with the condition. What those individuals will require is a therapy that will be able to replace the lost cells (particularly the dopamine neurons). And researchers are also spending a great deal of time and effort on findings ways to do this. One of the most viable approaches at present is cell transplantation therapy. This approach involves actually injecting cells back into the brain to adopt the functions of the lost cells.
How does cell transplantation work?
We have discussed the history of cell transplantation in a previous post (Click here to read that post), and today we are simply going to focus on the ways this experimental treatment is being taken forward in the clinic.
Many different types of cells have been tested in cell transplantation experiments for Parkinson’s disease (Click here for a review of this topic), but to date the cells that have given the best results have been those dissected from the developing midbrain of aborted embryos.
This now old fashioned approach to cell transplantation involved dissecting out the region of the developing dopamine neurons from a donor embryo, breaking up the tissue into small pieces that could be passed through a tiny syringe, and then injecting those cells into the brain of a person with Parkinson’s disease.
The old cell transplantation process for Parkinson’s disease. Source: The Lancet
Critically, the people receiving this sort of transplant would require ‘immunosuppression treatment’ for long periods of time after the surgery. This additional treatment involves taking drugs that suppress the immune system’s ability to defend the body from foreign agents. This step is necessary, however, in order to stop the body’s immune system from attacking the transplanted cells (which would not be considered ‘self’ by the immune system), allowing those cells to have time to mature, integrate into the brain and produce dopamine.
The transplanted cells are injected into an area of the brain called the putamen. This is one of the main regions of the brain where the dopamine neurons of the substantia nigra release their dopamine. The image below demonstrates the loss of dopamine (the dark staining) over time as a result of Parkinson’s disease (PD):
The loss of dopamine in the putamen as Parkinson’s disease progresses. Source: Brain
In cell transplant procedures for Parkinson’s disease, multiple injections are usually made in the putamen, allowing for deposits in different areas of the structure. These multiple sites allow for the transplanted cells to produce dopamine in the entire extent of the putamen. And ideally, the cells should remain localised to the putamen, so that they are not producing dopamine in areas of the brain where it is not desired (possibly leading to side effects).
Targeting transplants into the putamen. Source: Intechopen
Postmortem analysis – of the brains of individuals who have previously received transplants of dopamine neurons and then subsequently died from natural causes – has revealed that the transplanted cells can survive the surgical procedure and integrate into the host brain. In the image below, you can see rich brown areas of the putamen in panel A. These brown areas are the dopamine producing cells (stained in brown). A magnified image of individual dopamine producing neurons can be seen in panel B:
Transplanted dopamine neurons. Source: Sciencedirect
The transplanted cells take several years to develop into mature neurons after the transplantation surgery, and the benefits of the transplantation technique may not be apparent for some time (2-3 years on average). Once mature, however, it has also been demonstrated (using brain imaging techniques) that these transplanted cells can produce dopamine. As you can see in the images below, there is less dopamine being processed (indicated in red) in the putamen of the Parkinsonian brain on the left than the brain on the right (several years after bi-lateral – both sides of the brain – transplants):
Brain imaging of dopamine processing before and after transplantation. Source: NIH
Sounds like a great therapy for Parkinson’s disease right?
So why aren’t we doing it???
1. The tissue used in the old approach for cell transplantation in Parkinson’s disease was dissected from embryonic brains. Obviously there are serious ethical and moral problems with using this kind of tissue. There is also a difficult problem of supply: tissue from at least 3 embryos is required for transplanting each side of the brain (6 embryos in total). Given these issues, researchers have focused their attention on a less controversial and more abundant supply of cells: brain cells derived from embryonic stem cells (the new approach to cell transplantation).
Human embryonic stem cells. Source: Wikipedia
2. The second reason why cell transplantation is not more widely available is that in the mid 1990’s, the US National Institutes of Health (NIH) provided funding for the two placebo-controlled, double blind studies to be conducted to test the efficacy of the approach. Unfortunately, both studies failed to demonstrate any beneficial effects on Parkinson’s disease features.
In addition, many (15% – 50%) of transplanted subjects developed what are called ‘graft-induced dyskinesias’. This involves the subjects display uncontrollable/erratic movement (or dyskinesias) as a result of the transplanted cells. 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).
Both of the NIH trials have been criticised by experts in the field for various procedural failings that could have contributed to the failures. But the overall negative results left a dark shadow over the technique for the better part of a decade. Researchers struggled to get funding for their research.
And this is the reason why many researchers are now urging caution with any new attempts at cell transplantation clinical trials in Parkinson’s disease – any further failures will really harm the field, if not kill if off completely.
Are there any clinical trials for cell transplantation in Parkinson’s disease currently being conducted?
Yes, there are currently two:
Firstly there is the Transeuro being conducted in Europe.
The Transeuro trial. Source: Transeuro
The Transeuro trial is an open label study, involving 40 subjects, transplanted in different 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, with success being based on brain imaging of dopamine release from the transplanted cells (PET scans). Based on the results of the previous NIH funding double blind clinical studies discussed above, only subject under 65 years of age have been enrolled in the study.
The European consortium behind the Transeuro trial. Source: Transeuro
In addition to testing the efficacy of the cell transplantation approach for Parkinson’s disease, another goal of the Transeuro trial is to optimise the surgical procedures with the aim of ultimately shifting over to an embryonic stem cells oriented technique in the near future with the proposed G-Force embryonic stem cell trials planned for 2018 (the Transeuro is testing the old approach to cell transplantation).
The second clinical study of cell transplantation for Parkinson’s disease is being conducted in Melbourne (Australia), by an American company called International Stem Cell Corporation.
This study is taking the new approach to cell transplantation, but the company is using a different type of stem cell to produce dopamine neurons in the Parkinsonian brain.
Specifically, the researchers will be transplanting human parthenogenetic stem cells-derived neural stem cells (hpNSC). These hpNSCs come from an unfertilized egg – that is to say, no sperm cell is involved. The female egg cell is chemically encouraged to start dividing and then it becoming a collection of cells that is called a blastocyst, which ultimately go on to contain embryonic stem cell-like cells.
The process of attaining embryonic stem cells. Source: Howstuffworks
This process is called ‘Parthenogenesis’, and it’s not actually as crazy as it sounds as it occurs naturally in some plants and animals (Click here to read more about this). Proponents of the parthenogenic approach suggest that this is a more ethical way of generating ES cells as it does not result in the destruction of a viable organism.
Regular readers of this blog will be aware that we are extremely concerned about this particular trial (Click here and here to read previous posts about this). Specifically, we worry that there is limited preclinical data from the company supporting the efficacy of these hpNSC cells being used in the clinical study (for example, researchers from the company report that the hpNSC cells they inject spread well beyond the region of interest in the company’s own published preclinical research – not an appropriate property for any cells being taken to the clinic). We have also expressed concerns regarding the researchers leading the study making completely inappropriate disclosures about the study while the study is ongoing (Click here to read more about this). Such comments only serve the interests of the company behind the study. And this last concern has been raised again with a quote in the Nature editorial about the Chinese trial:
“Russell Kern, chief scientific officer of the International Stem Cell Corporation in Carlsbad, California, which is providing the cells for and managing the Australian trial, says that in preclinical work, 97% of them became dopamine-releasing cells” (Source)
We are unaware of any preclinical data produced by Dr Kern and International Stem Cell Corporation…or ANY other research lab in the world that has achieved 97% dopamine-releasing cells. We (and others) would be interested in learning more about Dr Kerns amazing claim.
The International Stem Cell Corporation clinical trial is ongoing. For more details about this second ongoing clinical trial, please click here.
So what do we know about the new clinical study?
The clinical trial (Titled: A Phase I/II, Open-Label Study to Assess the Safety and Efficacy of Striatum Transplantation of Human Embryonic Stem Cells-derived Neural Precursor Cells in Patients With Parkinson’s Disease) will take place at the First Affiliated Hospital of Zhengzhou University in Henan province.
The researchers are planning to inject neuronal-precursor cells derived from embryonic stem cell into the brains of individuals with Parkinson’s disease. They have 10 subjects that they have found to be well matched to the cells that they will be injecting, which will help to limit the chance of the cells being rejected by the body.
- Incidence of treatment-emergent adverse events, as assessed by brain imaging and blood examination at 6 months post transplant.
Number of subjects with adverse events (such as the evidence of transplant failure or rejection)
In addition to these, there will also be a series of secondary outcome measures, which will include:
- Change in Unified Parkinson’s Disease Rating Scale (UPDRS) score at 12 months post surgery, when compared to baseline scores. Each subject was independently rated by two observers at each study visit and a mean score was calculated for analysis.
- Change in DATscan brain imaging at 12 months when compared to a baseline brain scan taken before surgery. DATscan imaging provides an indication of dopamine processing.
- Change in Hoehn and Yahr Stage at 12 months, compared to baseline scores. The Hoehn and Yahr scale is a commonly used system for Parkinson’s disease.
The trial will be a single group, non-randomized analysis of the safety and efficacy of the cells. The estimated date of completion is December 2020.
Why are some researchers concerned about the study?
Professor Qi Zhou, a stem-cell specialist at the Chinese Academy of Sciences Institute of Zoology will be leading the study and he has a REALLY impressive track record in the field of stem cell biology. His team undertaking this study have a great deal of experience working with embryonic stem cells, having published some extremely impressive research on this topic. But, (and it’s a big but) they have published a limited amount of research in peer-reviewed journals on cell transplantation in models of Parkinson’s disease. Lorenz Studer is one of the leading scientists in this field, was quoted in an editorial in the journal Nature this week:
“Lorenz Studer, a stem-cell biologist at the Memorial Sloan Kettering Cancer Center in New York City who has spent years characterizing such neurons ahead of his own planned clinical trials, says that “support is not very strong” for the use of precursor cells. “I am somewhat surprised and concerned, as I have not seen any peer-reviewed preclinical data on this approach,” he says.” (Source)
In addition to the lack of published research by the team undertaking the trial, the research community is also worried about the type of cells that are going to be transplanted in this clinical trial. Most of the research groups heading towards clinical trials in this area are all pushing embryonic stem cells towards a semi-differentiated state. That is, they are working on recipes that help the embryonic stem cells grow to the point that they have almost become dopamine neurons. Prof Zhou and his colleagues, however, are planning to transplant a much less differentiated type of cell called a neural-precursor cell in their transplants.
Neuronal-precursor cells. Source: Wired
Neuronal-precursors are very early stage brain cells. They are most likely being used in the study because they will survive the transplantation procedure better than a more mature neurons which would be more sensitive to the process – thus hopefully increasing the yield of surviving cells. But we are not sure how the investigators are planning to orient the cells towards becoming dopamine neurons at such an early stage of their development. Neuronal-precursors could basically become any kind of brain cell. How are the researchers committing them to become dopamine neurons?
Are these concerns justified?
We feel that there are justified reasons for concern.
While Prof Zhou and his colleagues have a great deal of experience with embryonic stem cells and have published very impressive research on that topic, the preclinical data for this trial is limited. In 2015, the research group published this report:
Title: Lmx1a enhances the effect of iNSCs in a PD model
Authors: Wu J, Sheng C, Liu Z, Jia W, Wang B, Li M, Fu L, Ren Z, An J, Sang L, Song G, Wu Y, Xu Y, Wang S, Chen Z, Zhou Q, Zhang YA.
Journal: Stem Cell Res. 2015 Jan;14(1):1-9.
PMID: 25460246 (This article is OPEN ACCESS if you would like to read it)
In this study, the researchers engineered embryonic stem cells to over-produce a protein called LMX1A to help produce dopamine neurons. LMX1A is required for the development of dopamine neurons (Click here to read more about this). The investigators then grew these cells in cell culture and compared their ability to develop into dopamine neurons against embryonic stem cells with normal levels of LMX1A. After 14 days in cell culture, 16% of the LMX1A cells were dopamine neurons, compared to only 5% of the control cells.
When the investigators transplanted these cells into a mouse model of Parkinson’s disease, they found that the behavioural recovery in the mice did not differ from the control injected mice, and when they looked at the brains of the mice 11 weeks after transplantation “very few engrafted cells had survived”.
In addition to this previously published work, the Chinese team do have unpublished research on 15 monkeys that have undergone the neuronal-precursor cell transplantation procedure having had Parkinson’s disease induced using a neurotoxin. The researchers have admitted that they initially did not see any improvements in movement (which is expected given the slow maturation of the cells). At the end of the first year, however, they examined the brains of some of the monkeys and they found that the transplanted stem cells had turned into dopamine-releasing cells (exactly what percentage of the cells were dopamine neurons is yet to be announced). The monkey study has been running for several years now and they have seen a 50% improvement in the motor ability of the remaining monkeys, supported by brain imaging data. The publication of this research is in preparation, but it probably won’t be available until after the trial has started.
So yes, there is a limited amount of preclinical research supporting the clinical trial.
As for concerns regarding the type of cells that are going to be transplanted:
Embryonic stem cells have robust tumour forming potential. If you inject them into the brain of mice, there is the potential for them to develop into dopamine neurons, but also tumours:
Title: Embryonic stem cells develop into functional dopaminergic neurons after transplantation in a Parkinson rat model
Authors: Bjorklund LM, Sánchez-Pernaute R, Chung S, Andersson T, Chen IY, McNaught KS, Brownell AL, Jenkins BG, Wahlestedt C, Kim KS, Isacson O.
Journal: Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):2344-9.
PMID: 11782534 (This article is OPEN ACCESS if you want to read it)
In this study, the researchers found that of the twenty-five rats that received embryonic stem cell injections into their brains to correct the modelled Parkinson’s disease, five rats died before completed behavioural assessment and the investigators found teratoma-like tumours in their brains – less than 16 weeks after the cells had been transplanted.
A teratoma (white spot) inside a human brain. Source: Radiopaedia
Given this risk of tumour formation, research groups in the cell transplantation field have been trying to push the embryonic stem cells as far away from their original pluripotent state and as close to a dopamine fate as possible without producing mature dopamine neurons which will not survive the transplantation procedure very well.
Prof Zhou’s less mature neuronal-precursor cells are closer to embryonic stem cells than dopamine neurons on this spectrum than the kinds of cells other research groups are testing in cell transplantation experiments. As a result, we are curious to know what precautions the investigators are taking to limit the possibility of an undifferentiated, still pluripotent embryonic stem cell from slipping into this study (the consequences could be disastrous). And given their results from the LMX1A study described above, we are wondering how they are planning to push the cells towards a dopamine fate. If they do not have answers to this issues, they should not be rushing to the clinic with these cells.
So yes, there are reasons for concern regarding the cells that the researchers plan to use in this clinical trial.
And, as with the International Stem Cell Corporation stem cell trial in Australia, we also worry that the follow up-period (or endpoint in the study) of 12 months is not long enough to determine the efficacy of these cells in improving Parkinson’s rating scores and brain imaging results. All of the previous clinical research in this field indicates that the transplanted cells require years of maturation before their dopamine production has an observable impact on the participant. Using 12 months as an end point for this study is tempting a negative result when the long term outcome could be positive.
As we mentioned above, any negative outcomes for these studies could have dire consequences for the field as a whole.
So what does it all mean?
Embryonic stem cells hold huge potential in the field of regenerative medicine. Their ability to become any cell type in the body means that if we can learn how to control them correctly, these cells could represent a fantastic new tool for future cell replacement therapies in conditions like Parkinson’s disease.
Strong demand for such therapies from groups like the Parkinsonian community, has resulted in research groups rushing to the clinic with different approaches using these cells. Concerns as to whether such approaches are ready for the clinic are warranted, if only because mistakes by individual research groups/consortiums in the past have caused delays for everyone in the field.
While China is very keen (and should be encouraged) to take bold steps in its ambition to be a world leader in this field, open and transparent access to extensive preclinical research would help assuage concerns within the research community that prudent care is being taken heading forward.
We’ll keep you aware of developments in this clinical trial.
EDITORIAL NOTE No.1 – It is important for all readers of this post to appreciate that cell transplantation for Parkinson’s disease is still experimental. Anyone declaring otherwise (or selling a procedure based on this approach) should not be trusted. While we appreciate the desperate desire of the Parkinson’s community to treat the disease ‘by any means possible’, bad or poor outcomes at the clinical trial stage for this technology could have serious consequences for the individuals receiving the procedure and negative ramifications for all future research in the stem cell transplantation area.
EDITORIAL NOTE No.2 – the author of this blog is associated with research groups conducting the current Transeuro transplantation trials and the proposed G-Force embryonic stem cell trials planned for 2018. He has endeavoured to present an unbiased coverage of the news surrounding the current clinical trials, though he shares the concerns of the Parkinson’s scientific community that the research supporting the current Australian trial is lacking in its thoroughness and will potentially jeopardise future work in this area. He is also concerned by the lack of peer-reviewed published research on cell transplantation in models of Parkinson’s disease for the proposed clinical studies in China.
The banner for today’s post was sourced from Ozy
Being a proud kiwi, I am happy to highlight and support any research coming out of New Zealand.
Recently a new commentary has been published suggesting that living in the NZ city of Rotorua (‘Roto-Vegas‘ to the locals) may decrease the risk of developing Parkinson’s disease.
In today’s post, we will review the research behind the idea and discuss what it could mean for people with neurodegenerative conditions, like Parkinson’s disease.
The geothermal wonderlands of Rotorua. Source: Audleytravel
Rotorua is a small city in the central eastern area of the North Island of New Zealand (Aotearoa in the indigenous Māori language).
The name Rotorua comes from the Māori language (‘roto’ meaning lake and rua meaning ‘two’). The full Māori name for the spot is actually Te Rotorua-nui-a-Kahumatamomoe. The early Māori chief and explorer Ihenga named it after his uncle Kahumatamomoe. But given that it was the second major lake found in Aotearoa (after lake Taupo in the centre of the North Island), the name that stuck was Rotorua or ‘Second lake’.
Maori culture. Source: TamakiMaoriVillage
Similar to lake Taupo, Rotorua is a caldera resulting from an ancient volcanic eruption (approximately 240,000 years ago). The lake that now fills it is about 22 km (14 mi) in diameter.
Lake Rotorua. Source: Teara
The volcano may have disappeared, but the surrounding region is still full of geothermal activity (bubbling mud pools and geysers), providing the region with abundant renewable power and making the city a very popular tourist destination.
Tourist playing with mud. Source: Rotoruanz
Before visiting the city, however, travellers should be warned that Rotorua’s other nicknames include “Sulphur City” and “Rotten-rua”, because of the smell that results from the geothermal activity.
And speaking from personal experience, the “rotten eggs” smell is prevalent.
Interesting, but what has this got to do with the science of Parkinson’s disease?
Well, the rotten egg smell is the result of hydrogen sulfide emissions, and recently it has been suggested that this pungent gas may be having positive benefits on people, particularly with regards to Parkinson’s disease.
This idea has been proposed by Dr Yusuf Cakmak at the University of Otago in a recent commentary:
Title: Rotorua, hydrogen sulphide and Parkinson’s disease-A possible beneficial link?
Author: Cakmak Y.
Journal: N Z Med J. 2017 May 12;130(1455):123-125.
In his write up, Dr Cakmak points towards two studies that have been conducted on people from Rotorua. The first focused on examining whether there was any association between asthma and chronic obstructive pulmonary disease and exposure to hydrogen sulfide in Rotorua. By examining air samples and 1,204 participants, the investigators of that study no association (the report of that study is OPEN ACCESS and can be found by clicking here).
The second study is the more interesting of the pair:
Title: Chronic ambient hydrogen sulfide exposure and cognitive function.
Authors: Reed BR, Crane J, Garrett N, Woods DL, Bates MN.
Journal: Neurotoxicol Teratol. 2014 Mar-Apr;42:68-76.
PMID: 24548790 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators recruited 1,637 adults (aged 18-65 years) from Rotorua. They conducted neuropsychological tests on the subjects, measuring visual and verbal episodic memory, attention, fine motor skills, psychomotor speed and mood. The average amount of time the participants had lived in the Rotorua region was 18 years (ranging from 3-64 years). The researchers also made measurements of hydrogen sulfide levels at the participants homes and work sites.
While the researchers found no association between hydrogen sulfide exposure and cognitive ability, they did notice something interesting in the measures of fine motor skills: individuals exposed to higher levels of hydrogen sulfide displayed faster motor response times on tasks like finger tapping. Finger tapping speed is an important part of Parkinson’s Motor Rating Scale examination tests.
The investigators behind the study concluded that the levels of hydrogen sulfide in Rotorua do not have any detrimental effect on the individuals living in the area,
Dr Cakmak, however, wondered whether “relatively high, but safe, hydrogen sulfide levels in Rotorua could help protect the degradation of dopaminergic neurons associated with Parkinson’s Disease?” (based on the better performance on the motor response time).
Hang on a second, what exactly is hydrogen sulfide?
Hydrogen sulfide (chemical symbol: H2S) is a colourless gas. Its production often results from the the breaking down of organic material in the absence of oxygen, such as in sewers (this process is called anaerobic digestion. It also occurs in volcanic and geothermal conditions.
H2S. Source: Wikipedia
About 15 years ago, it was found in various organs in the body and termed a gasotransmitter. A gasotransmitter is a molecule that can be used to transmit chemical signals from one cell to another, which results in certain physiological reactions (oxygen, for example, is a gasotransmitter).
Hydrogen sulfide is now known to be cardioprotective (protection of the heart), and many years of research have demonstrated beneficial aspects of using it in therapy, such as vasodilation and lowering blood pressure, increasing levels of antioxidants, inhibiting inflammation, and activation of anti-apoptotic (anti-cell death) pathways. For a good review of hydrogen sulfide’s cardioprotective properties – click here.
The demonstration of the protective properties of hydrogen sulfide in other bodily organs have led neuroscientists to start investigating whether these same benefits could be utilised in treating disorders of the brain.
And the good news is: hydrogen sulfide can have positive benefits in the brain – Click here for a good review of the brain-related research.
Has other research been conducted on hydrogen sulfide regarding Parkinson’s disease?
Yes. And here is where the story starts to get really interesting.
Then hydrogen sulfide was tested in rodent models of Parkinson’s disease:
Title: Neuroprotective effects of hydrogen sulfide on Parkinson’s disease rat models.
Authors: Hu LF, Lu M, Tiong CX, Dawe GS, Hu G, Bian JS.
Journal: Aging Cell. 2010 Apr;9(2):135-46.
PMID: 20041858 (This article is OPEN ACCESS if you would like to read it)
In this study, the researchers firstly looked at what happens to hydrogen sulfide in the brains of rodent models of Parkinson’s disease. When rats were injected with a neurotoxin (6-OHDA) that kills dopamine neurons, the investigators found a significant drop in the level of hydrogen sulfide in the region where the dopamine cells reside (called the substantia nigra – an area of the brain severely affected in Parkinson’s disease).
Next the researchers gave some rodents the neurotoxin, waited three weeks and then began administering sodium hydrosulfide – which is a hydrogen sulfide donor – every day for a further 3 weeks. They found that this treatment significantly reduced the dopamine cell loss, motor problems and inflammation in the sodium hydrosulfide treated animals. Interestingly, they saw the same neuroprotective effect when they repeated the study with a different neurotoxin (Rotenone). The investigators concluded that hydrogen sulfide “has potential therapeutic value for treatment of Parkinson’s disease”.
And this first study was followed up one year later by a study investigating inhaled hydrogen sulfide:
Title: Inhaled hydrogen sulfide prevents neurodegeneration and movement disorder in a mouse model of Parkinson’s disease.
Authors: Kida K, Yamada M, Tokuda K, Marutani E, Kakinohana M, Kaneki M, Ichinose F.
Journal: Antioxid Redox Signal. 2011 Jul 15;15(2):343-52.
PMID: 21050138 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators gave mice a neurotoxin (MPTP) and then had them breathe air with or without hydrogen sulfide (40 ppm) for 8 hours per day for one week. The mice that inhaled hydrogen sulfide displayed near normal levels of motor behaviour performance and significantly reduced levels of neurodegeneration (dopamine cell loss).
Inhalation of hydrogen sulfide also prevented the MPTP-induced activation of the brain’s helper cells (microglia and astrocytes) and increased levels of detoxification enzymes and antioxidant proteins (including heme oxygenase-1 and glutamate-cysteine ligase). Curiously, hydrogen sulfide inhalation did not significantly affect levels of reduced glutathione (we will come back to this in an upcoming post).
These first two preclinical results have been replicated many times now confirming the initial findings (Click here, here, here and here for examples). The researchers of the second ‘inhalation’ study concluded the study by suggesting that the potential therapeutic effects of hydrogen sulfide inhalation now needed to be examined in more disease relevant models of Parkinson’s disease.
And this is exactly what researchers did next:
Title: Sulfhydration mediates neuroprotective actions of parkin.
Authors: Vandiver MS, Paul BD, Xu R, Karuppagounder S, Rao F, Snowman AM, Ko HS, Lee YI, Dawson VL, Dawson TM, Sen N, Snyder SH.
Journal: Nat Commun. 2013;4:1626. doi: 10.1038/ncomms2623.
PMID: 23535647 (This article is OPEN ACCESS if you would like to read it)
The researchers conducting this study were interested in the interaction of hydrogen sulfide with the Parkinson’s disease-associated protein Parkin (also known as PARK2). They found that hydrogen sulfide actively modified parkin protein – a process called sulfhydration – and that this enhances the protein’s level of activity.
They also noted that the level of Parkin sulfhydration in the brains of patients with Parkinson’s disease is markedly reduced (a 60% reduction). These finding imply that drugs that increase levels of hydrogen sulfide in the brain may be therapeutic.
Interestingly, cells with genetic mutations in another Parkinson’s disease related gene, DJ-1, also produce less hydrogen sulfide (click here to read more about this).
Has anyone ever looked at hydrogen sulfide and alpha synuclein?
Not that we are aware of.
Alpha synuclein is the Parkinson’s disease associated protein that clusters in the Parkinsonian brain and forms Lewy bodies.
But researchers have looked at hydrogen sulfide and amyloid formation:
Title: Hydrogen sulfide inhibits amyloid formation
Authors: Rosario-Alomar MF, Quiñones-Ruiz T, Kurouski D, Sereda V, Ferreira EB, Jesús-Kim LD, Hernández-Rivera S, Zagorevski DV, López-Garriga J, Lednev IK.
Journal: J Phys Chem B. 2015 Jan 29;119(4):1265-74.
PMID: 25545790 (This article is OPEN ACCESS if you would like to read it)
Amyloid formations are large clusters of misfolded proteins that are associated with neurodegenerative conditions, like Alzheimer’s disease and Parkinson’s disease. The researchers who conducted this study were interested in the behaviour of these misfolded protein in the presence of hydrogen sulfide. What they found was rather remarkable: the addition of hydrogen sulfide completely inhibited the formation amyloid fibrils (amyloid fibril plaques are found in brains of people with Alzheimer’s disease).
If the addition of hydrogen sulfide can reduce the level of clustered proteins in a model of Alzheimer’s disease, it would be interesting to see what it would do to alpha synuclein.
NOTE: Hydrogen sulfide levels are also reduced in the brains of people with Alzheimer’s disease (click here to read more on this topic)
Has hydrogen sulfide ever been tested in the clinic?
There are currently 17 clinical trials investigating hydrogen sulfide in various conditions (not Parkinson’s disease though).
So where can I get me some of that hydrogen sulfide?
Ok, so here is where we come in with the health warning section.
You see, hydrogen sulfide is a very dangerous gas. It is really not to be played with.
The gas is both corrosive and flammable. More importantly, at high concentrations, hydrogen sulfide gas can be fatal almost immediately (>1000 parts per milllion – source: OSHA). And the gas only exhibits the “rotten eggs” smell at low concentrations. At higher concentrations it becomes undetectable due to olfactory paralysis (luckily for the folks in Rotorua, the levels of hydrogen sulfide gas there are between 20-25 parts per billion).
Thus, we do not recommend readers to rush out and load up on hydrogen sulfide gas.
There are many foods that contain hydrogen sulfide.
For example, garlic is very rich in hydrogen sulfide. Another rich source is cooked beef, which has about 0.6mg of hydrogen sulfide per pound – cooked lamb has closer to 0.9 milligrams per pound. Heated dairy products, such as skim milk, can have approximately 3 milligrams of hydrogen sulfide per gallon, and cream has slightly more than double that amount.
Any significant change in diet by a person with Parkinson’s disease should firstly be discussed with a trained medical physician as we can not be sure what impact such a change would have on individualised treatment regimes.
What does it all mean?
Summing up: It would be interesting to look at the frequency of Parkinson’s disease in geothermal region of the world (the population of Rotorua is too small for such an analysis – 80,000 people).
Researchers believe that components of the gas emissions from these geothermal areas may be neuroprotective. Of particular interest is the gas hydrogen sulfide. At high levels, it is a very dangerous gas. At lower levels, however, researchers have shown that hydrogen sulfide has many beneficial properties, including in models of neurodegenerative conditions. These findings have led many to propose testing hydrogen sulfide in clinical trials for conditions like Parkinson’s disease.
Dr Cakmak, who we mentioned near the top of this post, goes one step further. He hypothesises that hydrogen sulfide may actually be one of the active components in the neuroprotective affect of both coffee and smoking – and with good reason. It was recently demonstrated that the certain gut bacteria, such as Prevotella, are decreased in people with Parkinson’s disease (see our post on this topic by clicking here). The consumption of coffee has been shown to help improve the Prevotella population in the gut, which may in term increase the levels of Prevotella-derived hydrogen sulfide. Similarly smokers have a decreased risk of developing Parkinson’s disease and hydrogen sulfide is a component of cigarette smoke.
All of these ideas still needs to be further tested, but we are curious to see where this research could lead. An inhaled neuroprotective treatment for Parkinson’s disease may have benefits for other neurodegenerative conditions.
Oh, and if anyone is interested, we are happy to put readers in contact with real estate agents in sunny ‘Rotten-rua’, New Zealand. The locals say that you gradually get used to the smell.
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. While some of the drugs/molecules discussed on this website are clinically available, they may have serious side effects. We therefore urge caution and professional consultation before any attempt to alter 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 Trover
The Federal Drug Administration (FDA) in the USA has approved the first drug in 22 years for treating the neurodegenerative condition of Amyotrophic lateral sclerosis (ALS).
The drug is called Edaravone, and it is only the second drug approved for ALS.
In today’s post we’ll discuss what this announcement could mean for Parkinson’s disease.
Lou Gehrig. Source: NBC
In 1969, Henry Louis “Lou” Gehrig was voted the greatest first baseman of all time by the Baseball Writers’ Association. He played 17 seasons with the New York Yankees, having signed with his hometown team in 1923.
For 56 years, he held the record for the most consecutive games played (2,130), and he was only prevented from continuing that streak when he voluntarily took himself out of the team lineup on the 2nd May, 1939, after his ability to play became hampered by the disease that now often bears his name. A little more than a month later he retired, and a little less than two years later he passed away.
Amyotrophic lateral sclerosis (or 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.
ALS in a nutshell. Source: Walkforals
In addition to Lou Gehrig, you may have heard of ALS via the ‘Ice bucket challenge‘ (see image in the banner of this post). In August 2014, an online video challenge went viral.
By July 2015, the ice bucket campaign had raised an amazing $115 million for the ALS Association.
Another reason you may have heard of ALS is that theoretical physicist, Prof Stephen Hawking also has the condition:
He was diagnosed with in a very rare early-onset, slow-progressing form of ALS in 1963 (at age 21) that has gradually left him wheel chair bound.
This is very interesting, but what does it have to do with Parkinson’s disease?
Individuals affected by ALS are generally treated with a drug called Riluzole (brand names Rilutek or Teglutik). Approved in December of 1995 by the FDA, this drug increases survival by approximately two to three months.
Until this last week, Riluzole was the only drug approved for the treatment of ALS.
So what happened this week?
On the 5th May, the FDA announced that they had approved a second drug for the treatment of ALS (Click here for the press release).
It is called Edaravone.
What is Edaravone?
Edaravone is a free radical scavenger – a potent antioxidant – that is marketed as a neurovascular protective agent in Japan by Mitsubishi Tanabe Pharma Corporation.
An antioxidant is simply a molecule that prevents the oxidation of other molecules.
Molecules in your body often go through a process called oxidation – losing an electron and becoming unstable. This chemical reaction leads to the production of what we call free radicals, which can then go on to damage cells.
What is a free radical?
A free radical is simply an unstable molecule – unstable because they are missing electrons. They react quickly with other molecules, trying to capture the needed electron to re-gain stability. Free radicals will literally attack the nearest stable molecule, stealing an electron. This leads to the “attacked” molecule becoming a free radical itself, and thus a chain reaction is started. Inside a living cell this can cause terrible damage, ultimately killing the cell.
Antioxidants are thus the good guys in this situation. They are molecules that neutralize free radicals by donating one of their own electrons. The antioxidant don’t become free radicals by donating an electron because by their very nature they are stable with or without that extra electron.
Thus when we say ‘Edaravone is a free radical scavenger’, we mean it’s really good at scavenging all those unstable molecules and stabilising them.
It is an intravenous drug (injected into the body via a vein) and administrated for 14 days followed by 14 days drug holiday.
So, again what has this got to do with Parkinson’s disease?
Well, it is easier to start a clinical trial of a drug if it is already approved for another disease.
And the good news is: Edaravone has been shown to be neuroprotective in several models of Parkinson’s disease.
In this post, we’ll lay out some of the previous research and try to make an argument justifying the clinical testing of Edaravone in Parkinson’s disease
Ok, so what research has been done so far in models of Parkinson’s disease?
The first study to show neuroprotection in a model of Parkinson’s disease was published in 2008:
Title: Role of reactive nitrogen and reactive oxygen species against MPTP neurotoxicity in mice.
Authors: Yokoyama H, Takagi S, Watanabe Y, Kato H, Araki T.
Journal: J Neural Transm (Vienna). 2008 Jun;115(6):831-42.
In this first study, the investigators assessed the neuroprotective properties of several drugs in a mouse model of Parkinson’s disease. The drugs included Edaravone (described above), minocycline (antibiotic discussed in a previous post), 7-nitroindazole (neuronal nitric oxide synthase inhibitor), fluvastatin and pitavastatin (both members of the statin drug class).
With regards to Edaravone, the news was not great: the investigators found that Edaravone (up to 30mg/kg) treatment 30 minutes before administering a neurotoxin (MPTP) and then again 90 minutes afterwards had no effect on the survival of the dopamine neurons (compared to a control treatment).
Not a good start for making a case for clinical trials!
This research report, however, was quickly followed by another from an independent group in Japan:
Title: Neuroprotective effects of edaravone-administration on 6-OHDA-treated dopaminergic neurons.
Authors: Yuan WJ, Yasuhara T, Shingo T, Muraoka K, Agari T, Kameda M, Uozumi T, Tajiri N, Morimoto T, Jing M, Baba T, Wang F, Leung H, Matsui T, Miyoshi Y, Date I.
Journal: BMC Neurosci. 2008 Aug 1;9:75.
PMID: 18671880 (This article is OPEN ACCESS if you would like to read it)
These researchers did find a neuroprotective effect using Edaravone (both in cell culture and in a rodent model of Parkinson’s disease), but they used a much higher dose than the previous study (up to 250 mg/kg in this study). This increase in dose resulted in a graded increase in neuroprotection – interestingly, these researchers also found that 30mg/kg of Edaravone had limited neuroprotective effects, while 250mg/kg exhibited robust dopamine cell survival and rescued the behavioural/motor features of the model even when given 24 hours after the neurotoxin.
The investigators concluded that “Edaravone might be a hopeful therapeutic option for PD, although several critical issues remain to be solved, including high therapeutic dosage of Edaravone for the safe clinical application in the future”
This results was followed by several additional studies investigating edaravone in models of Parkinson’s disease (Click here, here and here to read more on this). Of particular interest in all of those follow up studies was a report in which Edaravone treatment resulted in neuroprotective in genetic model of Parkinson’s disease:
Title: Edaravone prevents neurotoxicity of mutant L166P DJ-1 in Parkinson’s disease.
Authors: Li B, Yu D, Xu Z.
Journal: J Mol Neurosci. 2013 Oct;51(2):539-49.
DJ-1 is a gene that has been associated Parkinson’s disease since 2003. The gene is sometimes referred to as PARK7 (there are now more than 20 Parkinson’s associated genomic regions, which each have a number and are referred to as the PARK genes). Genetic mutations in the DJ-1 gene can result in an autosomal recessive (meaning two copies of the mutated gene are required), early-onset form of Parkinson disease. For a very good review of DJ-1 in the context of Parkinson’s disease, please click here.
The exact function of DJ-1 is not well understood, though it does appear to play a role in helping cells deal with ‘oxidative stress’ – the over-production of those free radicals we were talking about above. Now given that edaravone is a potent antioxidant (reversing the effects of oxidative stress), the researchers conducting this study decided to test Edaravone in cells with genetic mutations in the DJ-1 gene.
Their results indicated that Edaravone was able to significantly reduce oxidative stress in the cells and improve the functioning of the mitochondria – the power stations in each cell, where cells derive their energy. Furthermore, Edaravone was found to reduce the amount of cell death in the DJ-1 mutant cells.
More recently, researchers have begun digging deeper into the mechanisms involved in the neuroprotective effects of Edaravone:
Title: Edaravone leads to proteome changes indicative of neuronal cell protection in response to oxidative stress.
Authors: Jami MS, Salehi-Najafabadi Z, Ahmadinejad F, Hoedt E, Chaleshtori MH, Ghatrehsamani M, Neubert TA, Larsen JP, Møller SG.
Journal: Neurochem Int. 2015 Nov;90:134-41.
PMID: 26232623 (This article is OPEN ACCESS if you would like to read it)
The investigators who conducted this report began by performing a comparative two-dimensional gel electrophoresis analyses of cells exposed to oxidative stress with and without treatment of Edaravone.
Um, what is “comparative two-dimensional gel electrophoresis analyses”?
Two-dimensional gel electrophoresis analyses allows researchers to determine particular proteins within a given solution. Mixtures of proteins are injected into a slab of gel and they are then separated according to two properties (mass and acidity) across two dimensions (left-right side of the gel and top-bottom of the gel).
A two-dimensional gel electrophoresis result may look something like this:
Two-dimensional gel electrophoresis. Source: Nature
As you can see, individual proteins have been pointed out on the image of this slab of gel.
In comparative two-dimensional gel electrophoresis, two samples of solution are analysed by comparing two slabs of gel that have been injected with protein mix solution from two groups of cells treated exactly the same except for one variable. Each solution gets its own slab of gel, and the differences between the gel product will highlight which proteins are present in one condition versus the other (based on the variable being tested).
In this experiment, the variable was Edaravone.
And when the researchers compared the proteins of Edaravone treated cells with those of cells not treated with Edaravone, they found that the neuroprotective effect of Edaravone was being caused by an increase in a protein called Peroxiredoxin-2.
Now this was a really interesting finding.
You see, Peroxiredoxin proteins are a family (there are 6 members) of antioxidant enzymes. And of particular interest with regards to Parkinson’s disease is the close relationship between DJ-1 (the Parkinson’s associated protein discussed above) and peroxiredoxin proteins (Click here, here, here and here to read more about this).
In addition, there are also 169 research reports dealing with the peroxiredoxin proteins and Parkinson’s disease (Click here to see a list of those reports).
So, what do you think about a clinical trial for Edaravone in Parkinson’s disease?
Are you convinced?
Regardless, it an interesting drug huh?
Are there any downsides to the drug?
One slight issue with the drug is that it is injected via a vein. Alternative systems of delivery, however, are being explored.A biotech company in the Netherlands, called Treeway is developing an oral formulation of edaravone (called TW001) and is currently in clinical development.
Edaravone was first approved for clinical use in Japan on May 23, 2001. With almost 17 years of Edaravone clinical use, a few adverse events including acute renal failure have been noted, thus precautions should be taken with individuals who have a history of renal problems. The most common side effects associated with the drug, however, are: fatigue, nausea, and some mild anxiety.
Click here for a good overview of the clinical history of Edaravone.
So what does it all mean?
The announcement from the FDA this week regarding the approval of Edaravone as a new treatment for ALS represents a small victory for the ALS community, but it may also have a significant impact on other neurodegenerative conditions, such as Parkinson’s disease.
Edaravone is a potent antioxidant agent, which has been shown to have neuroprotective effects in various models of Parkinson’s disease and other neurodegenerative conditions. It could be interesting to now test the drug clinically for Parkinson’s disease. Many of the preclinical research reports indicate that the earlier Edaravone treatment starts, the better the outcomes, so any initial clinical trials should focus on recently diagnosed subjects (perhaps even those with DJ-1 mutations).
The take home message of this post is: given that Edaravone has now been approved for clinical use by the FDA, it may be advantageous for the Parkinson’s community to have a good look at whether this drug could be repurposed for Parkinson’s disease.
It’s just a thought.
The banner for today’s post was sourced from Forbes