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???
The title of this post is a play on a Thomas Jefferson quote (“the olive tree is surely the richest gift of heaven“). Jefferson, the third President of the United States (1801 to 1809), was apparently quite the lover of food. During the Revolutionary War, while he was a U.S. envoy to France, Jefferson travelled the country. In Aix-en-Provence, he developed an admiration for olive trees, calling them “the most interesting plant in existence”.
Being huge food lovers ourselves, we here at the SoPD wholeheartedly agree with Jefferson. But we also think that olives are interesting for another reason:
They contain a chemical called Oleuropein.
In today’s post we’ll explore what is known about this chemical and discuss what it could mean for Parkinson’s disease.
Olives. Source: Gardeningknowhow
The olive, also known by the botanical name ‘Olea europaea,’ is an evergreen tree that is native to the Mediterranean, Asia and Africa, but now found around the world. It has a rich history of economic and symbolic importance within western civilisation. And the fruit of the tree also tastes good, either by themselves or in a salad or pasta dish.
Traditional diets of people living around the Mediterranean sea are very rich in extra-virgin olive oil. Olives are an excellent source of ‘good’ fatty acids (monounsaturated and di-unsaturated), antioxidants and vitamins. Indeed, research has shown that the traditional Mediterranean diet reduces the risk of heart disease (Click here to read more on this).
Olive oil. Source: Bonzonosvilla
There are also chemicals within the olive fruit that may have very positive benefits for Parkinson’s disease.
But before you rush out and gorge yourself on olives, we have one small piece of advice:
The chemical is called Oleuropein, and it is usually removed from olives due to its bitterness.
What is Oleuropein?
Oleuropein is a ‘phenylethanoid’ – a type of phenolic compound that is found in the leaf and the fruit of the olive. Phenolic compounds are produced by plants as a protective measure against different kinds of stress.
Oleuropein. Source: Wikipedia
The main phenolic compounds found in olives are hydroxytyrosol and oleuropein – both of which give extra-virgin olive oil its bitter taste and both have demonstrated neuroprotective effects.
More research has been done on oleuropein so we will focus on it here (for more on hydroxytyrosol – please click here).
Oleuropein has been found to have many interesting properties, such as:
The many properties of oleuropein. Source: Mdpi
What neuroprotective research has been done on Oleuropein?
Thus far, most of the research addressing this question has been conducted on models of Alzheimer’s disease. The first study
Title: Oleuropein aglycone protects transgenic C. elegans strains expressing Aβ42 by reducing plaque load and motor deficit.
Authors: Diomede L, Rigacci S, Romeo M, Stefani M, Salmona M.
Journal: PLoS One. 2013;8(3):e58893.
PMID: 23520540 (This article is OPEN ACCESS if you would like to read it)
The Italian researchers who conducted this study treated a microscopic worm model of Alzheimer’s disease with oleuropein aglycone. We should not that oleuropein aglycone is a hydrolysis product of oleuropein (a hydrolysis product is a chemical compound that is broken apart by the addition of water). The microscopic worm used in the study are called Caenorhabditis elegans:
Caenorhabditis elegans – cute huh? Source: Nematode
Caenorhabditis elegans (or simply C. Elegans) are tiny creatures that are widely used in biology because they can be easily genetically manipulated and their nervous system is very simple and well mapped out (they have just 302 neurons and 56 glial cells!). The particular strain of C. elegans used in this first study produced enormous amounts of a protein called Aβ42.
Amyloid beta (or Aβ) is the bad boy/trouble maker of Alzheimer’s disease; considered to be critically involved in the condition. A fragment of this protein (called Aβ42) begins clustering in the brains of people with Alzheimer’s disease. This clustering of Aβ42 goes on to form the plaques that are so characteristic of the Alzheimer’s affected brain.
The Italian researchers conducting this study had previously shown that oleuropein can inhibit the ability of Aβ42 to aggregate in cells growing in culture dishes (Click here to read more about that study), and they wanted to see if oleuropein had the same properties in actual live animals. So they chose the C. Elegans that had been genetically engineered to produce a lot of Aβ42 to test this idea.
In the C. Elegans that produce a lot of Aβ42 gradually become paralysed and their lives are shortened. By treating these worms with oleuropein, however, the Italian researchers found that there was less aggregation of Aβ42 (though the levels of the protein stayed the same), resulting in less plaque formation, and improved mobility (>50% reduction in paralysis) and survival compared to untreated Aβ42 producing C. Elegans.
Encouraged by this result, the researchers next moved on to studies in mice:
Title: The polyphenol oleuropein aglycone protects TgCRND8 mice against Aß plaque pathology.
Authors: Grossi C, Rigacci S, Ambrosini S, Ed Dami T, Luccarini I, Traini C, Failli P, Berti A, Casamenti F, Stefani M.
Journal: PLoS One. 2013 Aug 8;8(8):e71702.
PMID: 23951225 (This article is OPEN ACCESS if you would like to read it)
For this study, the Italian researchers used the genetically engineered TgCRND8 mice. These mice have a mutant form of amyloid precursor protein (which, similar to Aβ42, is associated with Alzheimer’s disease). In the brains of these mice, amyloid clustering begins at 3 months of age, and dense plaques are evident from 5 months of age. The mice also exhibit a clear learning impairment from 3 months of age.
By treating these mice with oleuropein aglycone, the researchers observed a remarkable reduction in plaques in the brain, and those that were present appeared less compact and “fluffy” (their very technical description, not ours). In addition, there was a reduction in the activation of astrocytes and microglia (the helper cells in the brain), indicating a healthier environment.
These same researchers have observed the same results in a rat model of Alzheimer’s disease in a report published the next year (Click here to read more about this).
Interestingly, the oleuropein treated TgCRND8 mice also displayed a major increase in autophagy activity. As we discussed in our previous post (Click here to read that post), autophagy is the rubbish disposal/recycling system of each cell, and increasing the activity of this system can help to keep cells health (particularly if there is a lot of a genetically engineered protein present!).
The Italian researchers repeated this study, and published the results this year, with an interesting twist:
Title: Oleuropein aglycone and polyphenols from olive mill waste water ameliorate cognitive deficits and neuropathology.
Authors: Pantano D, Luccarini I, Nardiello P, Servili M, Stefani M, Casamenti F.
Journal: Br J Clin Pharmacol. 2017 Jan;83(1):54-62.
In this study, the researchers tested the same genetically engineered mice, but with two different treatments:
- Two much lower doses of oleuropein (4 and 100 times lower)
- A mixture of polyphenols from olive mill concentrated waste water
The lowest dose of oleuropein (100 times less oleuropein than the previous study) did not provide any significant improvements for the mice, but the intermediate dose (only 4 times less oleuropein than the previous study) did provide significant benefits. These result indicate that there is a dose-dependent range to the beneficial properties of oleuropein.
The researchers also observed very similar beneficial effects from the mice drinking a mixture of polyphenols from olive mill concentrated waste water. Given these results, the investigators are now seeking to design appropriate conditions to perform a clinical trial to assess better the possible use of oleuropein (or a mix of olive polyphenols) against Alzheimer’s disease.
Ok, but what research has been done with oleuropein and Parkinson’s disease?
Unfortunately, not much.
A research group in Iran has looked at the effect of oleuropein in aged rodents and found an interesting result:
Title: Antioxidant role of oleuropein on midbrain and dopaminergic neurons of substantia nigra in aged rats.
Authors: Sarbishegi M, Mehraein F, Soleimani M.
Journal: Iran Biomed J. 2014;18(1):16-22.
PMID: 24375158 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators took twenty aged rats (18-month-old) and randomly assigned them to two groups: a treatment group (which received a daily dose of 50 mg/kg of oleuropein for 6 months) and a control group (which received just water). Following these treatments, the investigators found an increase in the activity of anti-oxidant agents (such as superoxide dismutase, catalase and glutathione) in the treatment group compared to control group. The treated rats also had significantly more dopamine neurons in the region of the brain affected by Parkinson’s disease (the substantia nigra). The investigators concluded that oleuropein consumption in a daily diet may be useful in reducing oxidative stress damage by increasing the antioxidant activity in the brain.
This first study was followed more recently by a report from a group in Quebec (Canada) who investigated oleuropein use in a cell culture model of Parkinson’s disease:
Title: Oleuropein Prevents Neuronal Death, Mitigates Mitochondrial Superoxide Production and Modulates Autophagy in a Dopaminergic Cellular Model.
Authors: Achour I, Arel-Dubeau AM, Renaud J, Legrand M, Attard E, Germain M, Martinoli MG.
Journal: Int J Mol Sci. 2016 Aug 9;17(8).
PMID: 27517912 (This article is OPEN ACCESS if you would like to read it)
The researcher conducting this study wanted to determine if oleuropein could prevent neuronal degeneration in a cellular model of Parkinson’s disease. They exposed cells to the neurotoxin 6-hydroxydopamine (6-OHDA) and then investigated mitochondrial oxidative stress and autophagy.
What is mitochondrial oxidative stress?
Mitochondria are the power house of each cell. They keep the lights on. Without them, the lights go out and the cell dies.
Mitochondria and their location in the cell. Source: NCBI
Oxidative stress results from too much oxidation. Oxidation is the loss of electrons from a molecule, which in turn destabilises the molecule. Think of iron rusting. Rust is the oxidation of iron – in the presence of oxygen and water, iron molecules will lose electrons over time. Given enough time, this results in the complete break down of objects made of iron.
Rust, the oxidation of metal. Source: TravelwithKevinandRuth
The exact same thing happens in biology. Molecules in your body go through a similar process of oxidation – losing electrons and becoming unstable. This chemical reaction leads to the production of what we call free radicals, which can then go on to damage cells. A free radical is an unstable molecule – unstable because they are missing electrons.
How free radicals and antioxidants work. Source: h2miraclewater
In an unstable format, free radicals bounce all over the place, reacting quickly with other molecules, trying to capture the much needed electron to re-gain stability. Free radicals will literally attack the nearest stable molecule, to steal 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.
Now if this oxidative process starts in the mitochondria, it can be very bad for a cell.
And what is autophagy?
Yes, the researchers also looked at autophagy levels in their cells. Autophagy is an absolutely essential function in a cell. Without autophagy, old proteins and mitochondria will pile up making the cell sick and eventually it dies. Through the process of autophagy, the cell can break down the old protein, clearing the way for fresh new proteins to do their job.
Think of autophagy as the waste disposal/recycling process of the cell.
The process of autophagy. Source: Wormbook
Waste material inside a cell is collected in membranes that form sacs (called vesicles). These vesicles then bind to another sac (called a lysosome) which contains enzymes that will breakdown and degrade the waste material. The degraded waste material can then be recycled or disposed of by spitting it out of the cell.
Ok, so what did the researchers find?
Well, by pretreating the their cells with oleuropein 3 hours before exposing them to the neurotoxin, the investigators found a significant neuroprotective effect. There was a significant reduction in mitochondrial production of free radicals, and the investigators found an important role for oleuropein in the regulation of autophagy.
And the good news is that other research groups have observed similar beneficial effects of oleuropein in cell culture models of Parkinson’s disease (Click here to read more about that).
The bad news is: that is all the published research on oleuropein and Parkinson’s disease we could find (and we would be happy to be corrected on this if people are aware of other reports!).
So what does Oleuropein do in the brain?
This is a good question, but with so little research done in this area, it is hard to answer.
We know that oleuropein is well absorbed by the human body and that it is relatively stable (Click here to read more on this). In addition, it can cross the blood-brain-barrier – in rodents at least (Click here to read more on that).
Obviously (based on the research we described above), we know that oleuropein has anti-oxidant promoting activities. In addition, it appears to be doing something with regards to autophagy. And it may be regulating autophagy by acting as an inhibitor of mammalian target of rapamycin (mTOR) activation.
What is mTOR?
mTOR is a protein that binds with other proteins to form the nexus of a signalling pathway which integrates both intracellular and extracellular signals (such asnutrients, growth factors, and cellular energy status) and then serves as one of the central instructors of how the cell should respond.
For example, insulin can signal to mTOR the status of glucose levels in the body. mTOR also deals with infectious or cellular stress-causing agents, thus it could be involved in a cells response to conditions like Parkinson’s disease.
Factors that activate mTOR. Source: Selfhacked
One important property of mTOR is its ability to block autophagy (the recycling process of the cell that we discussed above). Recently, the Italian researchers whose work we reviewed above, found that oleuropein can activate autophagy by blocking the mTOR pathway:
Title: Oleuropein aglycone induces autophagy via the AMPK/mTOR signalling pathway: a mechanistic insight.
Authors: Rigacci S, Miceli C, Nediani C, Berti A, Cascella R, Pantano D, Nardiello P, Luccarini I, Casamenti F, Stefani M.
Journal: Oncotarget. 2015 Nov 3;6(34):35344-57.
PMID: 26474288 (This article is OPEN ACCESS if you would like to read it)
The researchers conducting this study found that treatment with oleuropein caused an increase in autophagy in both cell culture and in a mouse model of Alzheimer’s disease, and they demonstrated that it achieved this by blocking the mTOR pathway.
Has anyone ever looked at oleuropein in the clinic?
No, not to our knowledge (and we are happy to be corrected on this).
There have been six clinical trials of olive leaf extract (the majority of which is oleuropien), but none of them have been focused on any neurological conditions.
So oleuropein is safe then?
It is a widely available supplement that a lot of people use to help lower bad cholesterol and blood pressure, so yes it can be considered safe. But any decision to experiment with oleuropein should only be made in consultation with your regular medically trained physician.
Why? Because there are always caveats.
Importantly, individuals with low blood pressure and diabetes may suffer even lower blood pressure and blood glucose levels as a result of consumption of oleuropein. Oleuropein may also interact with other pharmaceutical drugs that are designed to lower blood pressure or regulate diabetes. Such interactions could be dangerous.
And this is a particularly important factor for Parkinson’s disease as up to 30% of people with Parkinson’s may be glucose intolerant (Click here to see our post on Parkinson’s & diabetes).
Those who experience symptoms such as headache, nausea, flu-like symptoms, fainting, dizziness, and other life threatening symptoms should medical attention immediately.
What does it all mean?
We are grateful to regular reader (Don) who brought oleuropein to our attention. It is a very interesting chemical and we are definitely intrigued by it. We would certainly like to see more research on oleuropein in models of Parkinson’s disease.
Attentive readers will have noticed that most of the research discussed above have been conducted in the last 5-10 years. This suggests that oleuropein research is still in its infancy, particularly with regards to research on neurological conditions. And we hope that by reporting on it here, we will be bringing it to the attention of researchers.
Oleuropein is extracted from all parts of the olive tree (the leaves, bark, root, and fruit). It forms part of the defence system of the olive tree against stress or infection. Perhaps we could apply some of its interesting properties to Parkinson’s disease.
EDITORIAL NOTE: Under absolutely no circumstances should anyone reading the material on this website consider it medical advice. The information 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 and supplements discussed on this website are clinically available, they may have serious side effects. We urge caution and professional consultation before altering any treatment regime. SoPD can not be held responsible for any actions taken based on the information provided here.
The banner for this post was sourced from jrbenjamin
Recently the results of a small clinical study looking at Resveratrol in Alzheimer’s disease were published. Resveratrol has long been touted as a miracle ingredient in red wine, and has shown potential in animal models of Parkinson’s disease, but it has never been clinically tested.
Is it time for a clinical trial?
In today’s post we will review the new clinical results and discuss what they could mean for Parkinson’s disease.
From chemical to wine – Resveratrol. Source: Youtube
In 2006, there was a research article published in the prestigious journal Nature about a chemical called resveratrol that improved the health and survival of mice on a high-calorie diet (Click here for the press release).
Title: Resveratrol improves health and survival of mice on a high-calorie diet.
Authors: Baur JA, Pearson KJ, Price NL, Jamieson HA, Lerin C, Kalra A, Prabhu VV, Allard JS, Lopez-Lluch G, Lewis K, Pistell PJ, Poosala S, Becker KG, Boss O, Gwinn D, Wang M, Ramaswamy S, Fishbein KW, Spencer RG, Lakatta EG, Le Couteur D, Shaw RJ, Navas P, Puigserver P, Ingram DK, de Cabo R, Sinclair DA.
Journal: Nature. 2006 Nov 16;444(7117):337-42.
PMID: 17086191 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators placed middle-aged (one-year-old) mice on either a standard diet or a high-calorie diet (with 60% of calories coming from fat). The mice were maintained on this diet for the remainder of their lives. Some of the high-calorie diet mice were also placed on resveratrol (20mg/kg per day).
After 6 months of this treatment, the researchers found that resveratrol increased survival of the mice and insulin sensitivity. Resveratrol treatment also improved mitochondria activity and motor performance in the mice. They saw a clear trend towards increased survival and insulin sensitivity.
The report caused a quite a bit of excitement – suddenly there was the possibility that we could eat anything we wanted and this amazing chemical would safe us from any negative consequences.
That report was proceeded by numerous studies demonstrating that resveratrol could extend the life-span of various micro-organisms, and it was achieving this by activating a family of genes called sirtuins (specifically Sir1 and Sir2) (Click here, here and here for more on this).
Subsequent to these reports, there have been numerous scientific publications suggesting that resveratrol is capable of all manner of biological miracles.
Wow! So what is resveratrol?
Do you prefer your wine in pill form? Source: Patagonia
Resveratrol is a chemical that belongs to a group of compounds called polyphenols. They are believed to act like antioxidants. Numerous plants produce polyphenols in response to injury or when the plant is under attack by pathogens (microbial infections).
Fruit are a particularly good source of resveratrol, particularly the skins of grapes, blueberries, raspberries, mulberries and lingonberries. One issue with fruit as a source of resveratrol, however, is that tests in rodents have shown that less than 5% of the oral dose was observed as free resveratrol in blood plasma (Source). This has lead to the extremely popular idea of taking resveratrol in the form of wine, in the hope that it could have higher bioavailability compared to resveratrol in pill form. Red wines have the highest levels of Resveratrol in their skins (particularly Mabec, Petite Sirah, St. Laurent, and pinot noir). This is because red wine is fermented with grape skins longer than is white wine, thus red wine contains more resveratrol.
EDITOR’S NOTE: Sorry to rain on the parade, but it is important to note here that red wine actually contains only small amounts of resveratrol – less than 3-6 mg per bottle of red wine (750ml). Thus, one would need to drink a great deal of red wine per day to get enough resveratrol (the beneficial effects observed in the mouse study described above required 20mg/kg of resveratrol per day. For a person weighting 80kg, this would equate to 1.6g per day or approximately 250 750ml bottles).
We would like to suggest that consuming red wine would NOT be the most efficient way of absorbing resveratrol. And obviously we DO NOT recommend any readers attempt to drink 250 bottles per day (if that is even possible).
The recommended daily dose of resveratrol should not exceed 250 mg per day over the long term (Source). Resveratrol might increase the risk of bleeding in people with bleeding disorders. And we recommend discussing any change in treatment regimes with your doctor before starting.
So what did they find in the Alzheimer’s clinical study?
Well, the report we will look at today is actually a follow-on to published results from a phase 2/safety clinical trial that were reported in 2015:
Title: A randomized, double-blind, placebo-controlled trial of resveratrol for Alzheimer disease.
Authors: Turner RS, Thomas RG, Craft S, van Dyck CH, Mintzer J, Reynolds BA, Brewer JB, Rissman RA, Raman R, Aisen PS; Alzheimer’s Disease Cooperative Study.
Title: Neurology. 2015 Oct 20;85(16):1383-91.
PMID: 26362286 (This article is OPEN ACCESS if you would like to read it)
The researchers behind the study are associated with the Georgetown research group that conducted the initial Nilotinib clinical study in Parkinson’s disease (Click here for our post on this).
The investigators conducted a randomized, placebo-controlled, double-blind, multi-center phase 2 trial of resveratrol in individuals with mild to moderate Alzheimer disease. The study lasted 52 weeks and involved 119 individuals who were randomly assigned to either placebo or resveratrol 500 mg orally daily treatment.
EDITOR’S NOTE: We appreciate that is daily dose exceeds the recommended daily dose mentioned above, but it is important to remember that the participants involved in this study were being closely monitored by the study investigators.
Brain imaging and samples of cerebrospinal fluid (the liquid within which the brain sits) were collected at the start of the study and after completion of treatment.
The most important result of the study was that resveratrol was safe and well-tolerated. The most common side effect was feeling nausea and diarrhea in approximately 42% of individuals taking resveratrol (curiously 33% of the participants blindly taking the placebo reported the same thing). There was also a weight loss effect between the groups, with the placebo group gaining 0.5kg on average, while the resveratrol treated group lost 1kg on average.
The second important take home message is that resveratrol crossed the blood–brain barrier in humans. The blood brain barrier prevents many compounds from having any effect in the brain, but it does not stop resveratrol.
The investigators initially found no effects of resveratrol treatment in various Alzheimer’s markers in the cerebrospinal fluid. Not did they see any effect in brain scans, cognitive testing, or glucose/insulin metabolism. The authors were cautious about their conclusions based on these results, however, as the study was statistically underpowered (that is to say, there were not enough participants in the various groups) to detect clinical benefits. They recommended a larger study to determine whether resveratrol is actually beneficial.
While exploring the idea of a larger study, the researchers have re-analysed some of the data, and that brings us to the report we want to review today:
Title: Resveratrol regulates neuro-inflammation and induces adaptive immunity in Alzheimer’s disease.
Authors: Moussa C, Hebron M, Huang X, Ahn J, Rissman RA, Aisen PS, Turner RS.
Journal: J Neuroinflammation. 2017 Jan 3;14(1):1. doi: 10.1186/s12974-016-0779-0.
PMID: 28086917 (This article is OPEN ACCESS if you would like to read it)
In this report, the investigators conducted a retrospective study re-examining the cerebrospinal fluid and blood plasma samples from a subset of subjects involved in the clinical study described above. In this study, they only looked at the subjects who started with very low levels in the cerebrospinal fluid of a protein called Aβ42.
Amyloid beta (or Aβ) is the bad boy/trouble maker of Alzheimer’s disease; considered to be critically involved in the disease. A fragment of this protein (called Aβ42) begin clustering in the brains of people with Alzheimer’s disease and as a result, low levels of Aβ42 in cerebrospinal fluid have been associated with increased risk of Alzheimer’s disease and considered a possible biomarker of the condition (Click here to read more on this).
The resveratrol study investigators collected all of the data from subjects with cerebrospinal fluid levels of Aβ42 less than 600 ng/ml at the start of the study. This selection criteria gave them 19 resveratrol-treated and 19 placebo-treated subjects.
In this subset re-analysis study, resveratrol treatment appears to have slowed the decline in cognitive test scores (the mini-mental status examination), as well as benefiting activities of daily living scores and cerebrospinal fluid levels of Aβ42.
One of the most striking results from this study is the significant decrease observed in the cerebrospinal fluid levels of a protein called Matrix metallopeptidase 9 (or MMP9) after resveratrol treatment. MMP9 is slowly emerged as an important player in several neurodegenerative conditions, including Parkinson’s disease (Click here to read more on this). Thus the decline observed is very interesting.
This re-analysis indicates beneficial effects in some cases of Alzheimer’s as a result of taking resveratrol over 52 weeks. The researchers concluded that the findings of this re-analysis support the idea of a larger follow-up study of resveratrol in people with Alzheimer’s disease.
Ok, but what research has been done on resveratrol in Parkinson’s disease?
Yes, good question.
One of the earliest studies looking at resveratrol in Parkinson’s disease was this one:
Title: Neuroprotective effect of resveratrol on 6-OHDA-induced Parkinson’s disease in rats.
Authors: Jin F, Wu Q, Lu YF, Gong QH, Shi JS.
Journal: Eur J Pharmacol. 2008 Dec 14;600(1-3):78-82.
In this study, the researchers used a classical rodent model of Parkinson’s disease (using the neurotoxin 6-OHDA). One week after inducing Parkinson’s disease, the investigators gave the animals either a placebo or resveratrol (at doses of 10, 20 or 40 mg/kg). This treatment regime was given daily for 10 weeks and the animals were examined behaviourally during that time.
The researchers found that resveratrol improved motor performance in the treated animals, with them demonstrating significant results as early as 2 weeks after starting treatment. Resveratrol also reduced signs of cell death in the brain. The investigators concluded that resveratrol exerts a neuroprotective effect in this model of Parkinson’s disease.
Subsequent studies have also looked at what effect resveratrol could be having on the Parkinson’s disease associated protein alpha synuclein, such as this report:
Title: Effect of resveratrol on mitochondrial function: implications in parkin-associated familiarParkinson’s disease.
Authors: Ferretta A, Gaballo A, Tanzarella P, Piccoli C, Capitanio N, Nico B, Annese T, Di Paola M, Dell’aquila C, De Mari M, Ferranini E, Bonifati V, Pacelli C, Cocco T.
Journal: Biochim Biophys Acta. 2014 Jul;1842(7):902-15.
PMID: 24582596 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators collected skin cells from people with PARK2 associated Parkinson’s disease.
What is PARK2 associated Parkinson’s disease?
There are about 20 genes that have been associated with Parkinson’s disease, and they are referred to as the PARK genes. Approximately 10-20% of people with Parkinson’s disease have a genetic variation in one or more of these PARK genes (we have discussed these before – click here to read that post).
PARK2 is a gene called Parkin. Mutations in Parkin can result in an early-onset form of Parkinson’s disease. The Parkin gene produces a protein which plays an important role in removing old or sick mitochondria.
Hang on a second. Remind me again: what are mitochondria?
We have previously written about mitochondria (click here to read that post). Mitochondria are the power house of each cell. They keep the lights on. Without them, the lights go out and the cell dies.
Mitochondria and their location in the cell. Source: NCBI
You may remember from high school biology class that mitochondria are bean-shaped objects within the cell. They convert energy from food into Adenosine Triphosphate (or ATP). ATP is the fuel which cells run on. Given their critical role in energy supply, mitochondria are plentiful and highly organised within the cell, being moved around to wherever they are needed.
Another Parkinson’s associated protein, Pink1 (which we have discussed before – click here to read that post), binds to dysfunctional mitochondria and then grabs Parkin protein which signals for the mitochondria to be disposed of. This process is an essential part of the cell’s garbage disposal system.
Park2 mutations associated with early onset Parkinson disease cause the old/sick mitochondria are not disposed of correctly and they simply pile up making the cell sick. The researchers that collected the skin cells from people with PARK2 associated Parkinson’s disease found that resveratrol treatment partially rescued the mitochondrial defects in the cells. The results obtained from these skin cells derived from people with early-onset Parkinson’s disease suggest that resveratrol may have potential clinical application.
Thus it would be interesting (and perhaps time) to design a clinical study to test resveratrol in people with PARK2 associated Parkinson’s disease.
So why don’t we have a clinical trial?
Resveratrol is a chemical that falls into the basket of un-patentable drugs. This means that big drug companies are not interested in testing it in an expensive series of clinical trials because they can not guarantee that they will make any money on their investment.
There was, however, a company set up in 2004 by the researchers behind the original resveratrol Nature journal report (discussed at the top of this post). That company was called “Sirtris Pharmaceuticals”.
Sirtris identified compounds that could activate the sirtuins family of genes, and they began testing them. They eventually found a compound called SRT501 which they proposed was more stable and 4 times more potent than resveratrol. The company went public in 2007, and was subsequently bought by the pharmaceutical company GlaxoSmithKline in 2008 for $720 million.
From there, however, the story for SRT501… goes a little off track.
In 2010, GlaxoSmithKline stopped any further development of SRT501, and it is believed that this decision was due to renal problems. Earlier that year the company had suspended a Phase 2 trial of SRT501 in a type of cancer (multiple myeloma) because some participants in the trial developed kidney failure (Click here to read more).
Then in 2013, GlaxoSmithKline shut down Sirtris Pharmaceuticals completely, but indicated that they would be following up on many of Sirtris’s other sirtuins-activating compounds (Click here to read more on this).
Whether any of those compounds are going to be tested on Parkinson’s disease is yet to be determined.
We’ll let you know when we hear of anything.
So what does it all mean?
Summing up: Resveratrol is a chemical found in the skin of grapes and berries, which has been shown to display positive properties in models of neurodegeneration. A recent double blind phase II efficacy trial suggests that resveratrol may be having positive benefits in Alzheimer’s disease.
Preclinical research suggests that resveratrol treatment could also have beneficial effects in Parkinson’s disease. It would be interesting to see what effect resveratrol would have on Parkinson’s disease in a clinical study.
Perhaps we should have a chat to the good folks at ‘CliniCrowd‘ who are investigating Mannitol for Parkinson’s disease (Click here to read more about this). Maybe they would be interested in resveratrol for Parkinson’s disease.
ONE LAST EDITOR’S NOTE: Under absolutely no circumstances should anyone reading this material consider it medical advice. The material provided here is for educational purposes only. Before considering or attempting any change in your treatment regime, PLEASE consult with your doctor or neurologist. SoPD can not be held responsible for actions taken based on the information provided here.
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Exciting results published this week regarding a small phase 1b clinical trial of a new treatment for Alzheimer’s disease. In this post, we shall review the findings of the study and consider what they may mean for Parkinson’s disease.
An Alzheimer’s brain scans on the left, compared to a normal brain (right). Source: MedicalExpress
Alzheimer’s disease is the most common neurodegenerative disease, accounting for 60% to 70% of all cases of dementia. It is a progressive neurodegenerative condition, like Parkinson’s disease, affecting approximately 30 million people around the world.
Inside the brain, in addition to cellular loss, Alzheimer’s is characterised by the increasing presence of two features:
- Neurofibrillary tangles
- Amyloid plaques
A schematic demonstrating the difference between healthy and Alzheimer’s affected brains. Source: MmcNeuro
The tangles are aggregations of a protein called ‘Tau’ (we’ll comeback to Tau in a future post). These tangles reside within neurons initially, but as the disease progresses the tangles can be found in the space between cells – believed to be the last remains of a dying cell.
Amyloid plaques are clusters of proteins that outside the cells. A key component of the plaque is beta amyloid. Beta-amyloid is a piece of a larger protein that sits in the outer wall of nerve cells where it has certain functions. In certain circumstances, specific enzymes can cut it off and it floats away.
The releasing of Beta-Amyloid. Source: Wikimedia
Beta-amyloid is a very “sticky” protein and it has been believed that free floating beta-amyloid proteins begin sticking together, gradually building up into the large amyloid plaques. And these large plaques were considered to be involved in the neurodegenerative process of Alzheimer’s disease. Thus, for a long time scientists have attempted to reduce the amount of free-floating beta-amyloid in the brain. One of the main ways they do this is with antibodies.
What are antibodies?
An antibody is the foundation of our immune system. It is a Y-shaped structure, that is used to alert the body when a foreign or unhealthy agent is present.
An artist’s impression of a Y-shaped antibody. Source: Medimmune
Two arms off the Y-shaped antibody have what is called ‘Antigen binding sites‘. An antigen is a molecule that is capable of inducing a response from the immune system (usually a foreign agent, but it can be a sick/dying cell).
A schematic representation of an antibody. Source: Wikipedia
There are currently billions of antibodies in your body -each with specific sets of antigen binding sites – awaiting the presence of their antigen. Antibodies are present in two forms: secreted, free floating antibodies, and membrane-bound antibodies. Secreted antibodies are produced by B-cells, which are part of the immune system. And it’s this secreted form of antibody that modern science has used to produce new medicines.
Really? How does that work?
Scientists can make antibodies in the lab that target specific proteins and then inject those antibodies into a patient’s body and trick the immune system into removing that particular protein. This can be very tricky, and one has to be absolutely sure of the design of the antibody because you do not want any ‘off-target’ effects – the immune system removing a protein that looks very similar to the one you are actually targeting.
These manufactured antibodies are used in many different areas of medicine, particularly cancer (over 40 antibody preparations have been approved by the U.S. Food and Drug Administration for use in humans against cancers). Recently, large pharmaceutical companies (like Biogen) have been attempting to use these manufactured antibodies against other conditions, like Alzheimer’s disease.
Which brings us to the study published this week:
Title: The antibody aducanumab reduces Aβ plaques in Alzheimer’s disease.
Authors: Sevigny J, Chiao P, Bussière T, Weinreb PH, Williams L, Maier M, Dunstan R, Salloway S, Chen T, Ling Y, O’Gorman J, Qian F, Arastu M, Li M, Chollate S, Brennan MS, Quintero-Monzon O, Scannevin RH, Arnold HM, Engber T, Rhodes K, Ferrero J, Hang Y, Mikulskis A, Grimm J, Hock C, Nitsch RM, Sandrock A.
Journal: Nature. 2016 Aug 31;537(7618):50-6.
In this study, the researcher conducted a 12-month, double-blind, placebo-controlled trial of the antibody Aducanumab. This antibody specifically binds to potentially harmful beta-amyloid aggregates (both small and large). At the very start of the trial, each participants was given a brain scan which allowed the researchers to determine the baseline level of beta-amyloid in the brains of the subjects.
All together the study involved 165 people, randomly divided into five different groups: 4 groups received the 4 different concentrations of the drug (1, 3, 6 or 10 mg per kg) and 1 group which received a placebo treatment. Of these, 125 people completed the study which was 12 months long. Each month they received an injection of the respective treatment (remember these are manufactured antibodies, the body can’t make this particular antibody so it has to be repeated injected).
After 12 months of treatment, the subjects in the 3, 6 and 10 mg per kg groups exhibited a significant reduction in the levels of beta-amyloid protein in the brain (according to brain scan images), indicating that Aducanumab – the injected antibody – was doing it’s job. Individuals who received the highest doses of Aducanumab had the biggest reductions in beta-amyloid in the brain. Interestingly, this reduction in beta-amyloid in the brain was accompanied by a slowing of the clinical decline as measured by tests of dementia. Individuals treated with the placebo saw neither any reduction in their brain levels of beta amyloid nor their clinical decline.
The authors considered this study strong justification for larger phase III trials. Two of them are now in progress, with completion dates expected around 2020.
So this is a good thing right?
Yes, this is a very exciting result for the Alzheimer’s community. But the results must be taken with a grain of salt. We have discussed beta-amyloid in a previous post (Click here for that post). While it has long been considered the bad boy of the Alzheimer’s world, the function of beta-amyloid remains the subject of debate. Some researchers worry about the medical removal of it from the brain, especially if it has positive functions like anti-microbial (or disease fighting) properties.
Given that the treatment is given monthly and can thus be controlled, we can sleep easy knowing that disaster won’t befall the patients receiving the antibody. And if they continue to demonstrate a slowing/halting of the disease, it would represent a MASSIVE step forward in the neurodegenerative field. I guess what I am saying is that it is too soon to say. It will be interesting, however, to see what happens as these patients are followed up over time. And the two phase 3 clinical trials currently ongoing, which involve hundreds of participants, will provide a more definitive idea of how well the treatment is working.
So what does this have to do with Parkinson’s disease?
Yeah, so let’s get back to our area of interest: Parkinson’s disease. Biogen is the pharmaceutical company that makes the Alzheimer’s antibody (Aducanumab) discussed above. Biogen is also currently conducting a phase 1 safety trial (on normal healthy adults) of an antibody that targets the Parkinson’s disease associated protein, alpha synuclein. We are currently waiting to hear the results of that trial.
Several other companies have antibody-based approaches for Parkinson’s disease (all of them targeting the protein alpha synuclein). These companies include:
- Prothena – which completed phase 1 safety trials in March 2015 (Click here for more)
- Neuropore – which also completed phase 1 safety trials in March 2015 (Click here for more)
There are some worries regarding this approach, however. For example, alpha synuclein is highly expressed in red blood cells, and some researchers worry about what affects the antibodies may have on their function. In addition, alpha synuclein has been suspected of having anti-viral properties – reducing viruses ability to infect a cell and replicate (click here to read more on this). Thus, removal of alpha synuclein by injecting antibodies may not necessarily be a good thing for the brain’s defense system.
Unlike beta-amyloid, however, most of alpha synuclein’s activities seem to be conducted within the walls of brain cells, where antibodies can’t touch it. Thus the hope is that the only alpha synuclein being affected by the antibody treatment is the variety that is free floating around the brain.
The results of the Alzheimer’s study are a tremendous boost to the antibody approach to treating neurodegenerative diseases and it will be very interesting to watch how this plays out for Parkinson’s disease in the near future.
Watch this space!
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This week an interesting new study dealing with the biology of Alzheimer’s was published in the journal Science Translational Medicine. It has drawn a lot of attention as it may be turning our understanding of Alzheimer’s disease on it’s head. If the results are independently replicated and verified, it could potentially have major implications for Parkinson’s disease.
For the last 30 years, a protein called beta-amyloid has been considered one of the bad boys of the most common neurodegenerative condition, Alzheimer’s disease.
What is Alzheimer’s disease?
Alzheimer’s disease is a progressive neurodegenerative condition that can occur in middle or old age. It involves a generalized degeneration of the brain, not localised to specific regions like Parkinson’s disease.
What happens in the Alzheimer’s brain?
In the brain, in addition to cellular loss, Alzheimer’s is characterised by the presence of two features:
- Neurofibrillary tangles
- Amyloid plaques
The tangles are aggregations of a protein called ‘Tau’ (we’ll comeback to Tau in a future post). These tangles reside within neurons initially, but as the disease progresses the tangles can be found in the space between cells – believed to be the last remains of a dying cell.
A normal brain vs an Alzheimer’s affected brain. Source: MMCNeuro
Amyloid plaques are clusters of proteins that sit between cells. A key component of the plaque is beta amyloid. Beta-amyloid is a piece of a larger protein that sits in the outer wall of nerve cells where it has certain functions. In certain circumstances, specific enzymes can cut it off and it floats away.
Beta-Amyloid. Source: Wikimedia
Beta-amyloid is a very “sticky” protein and for a long time it has been believed that free floating beta-amyloid proteins begin sticking together, gradually building up into the large amyloid plaques. And these large plaques were considered to be involved in the neurodegenerative process of Alzheimer’s disease.
So what was discovered this week?
This week a study was published that suggests a new (and positive) function for beta amyloid:
Title: Amyloid-β peptide protects against microbial infection in mouse and worm models of Alzheimer’s disease.
Authors: Kumar DK, Choi SH, Washicosky KJ, Eimer WA, Tucker S, Ghofrani J, Lefkowitz A, McColl G, Goldstein LE, Tanzi RE, Moir RD.
Journal: Sci Transl Med. 2016 May 25;8(340):340ra72.
The researchers took three types of mice:
- genetically normal mice
- mice with no beta amyloid
- mice producing a lot of beta amyloid
They infected all of the mice with the microbe that causes meningitis, and they found that the mice producing a lot of beta amyloid lived significantly longer than other groups of mice. They then repeated the experiment in a species of microscopic worm – called C.elegans – and found similar results. These findings suggested that beta amyloid was having a positive effect in the brain.
But then they noticed something strange.
The mice producing a lot of beta amyloid usually do not develop a lot of protein aggregation until old age, but when the researchers looked in the brains of the mice they infected with meningitis, they found significant levels of aggregation in the mice producing a lot of beta amyloid but at a young age..
This led the researchers to conduct some cell culture experiments in which they watched what was happening to the bacteria and beta amyloid. They found that the beta amyloid was sticking to the bacteria and this was leading to the formation of protein aggregates.
The results of these experiments suggested to the researchers an intriguing possibility that beta amyloid may be playing a protective in the brain – acting as an immune system for the brain – against infection.
Thus the aggregations we see in the brains of people with Alzheimer’s may not be the cause of the cell death associated with the disease, but rather evidence of the ‘brain’s immune system’ trying to fight back against unknown infectious agents. The researcher’s of the study were quick to point out that this antimicrobial action of beta amyloid is simply a new function of the protein, and it may have nothing to do with the disease itself. But it will be interesting to see where this research goes next.
What has this got to do with Parkinson’s disease?
Parkinson’s disease is only definitive diagnosed at the postmortem stage. This is done by microscopic examination of the brain. In the brains of people with Parkinson’s disease, there are protein aggregates calls Lewy bodies. These are densely packed clusters of a protein called ‘alpha synuclein‘.
The brown spot is a Lewy body inside of a brain cell. Source: Cure Dementia
If the results of the study presented above are correct and beta amyloid is a protective protein in the brain against infection, could it not be that alpha synuclein may be playing a similar role? It is a fascinating idea that it will be interesting to test.
What are the implications of the study?
Currently, there are numerous clinical trials for Alzheimer’s disease, involving treatments that act against beta amyloid. If the study presented above is correct, and beta amyloid has a role in protecting the brain, these new treatments in clinical trial may actually be weakening the brain’s ability to fight infection.
Similarly, if alpha synuclein is found to exhibit ‘protective’ properties like beta amyloid, then the alpha synuclein vaccine clinical trials currently underway (in which the body’s immune system is primed to remove free floating alpha synuclein, in an attempt to stop the disease from spreading) may need to be reconsidered. At a minimum, investigations into whether alpha synuclein has antimicrobial properties need to be conducted.
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