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Showing posts with label mitochondria. Show all posts
Showing posts with label mitochondria. Show all posts

Thursday 17 August 2017

Viruses, Bacteria, Fungi, Parasites and Altered Gene Expression, Relevant to Autism






Today’s post started life as a review of how some viruses affect gene expression and may help cause, or just trigger flare-ups in, some neurological disorders ranging from autism to MS (multiple sclerosis). 
Some people with autism are treated with anti-viral drugs and, anecdotally, some do respond well.  This is not yet an area with hard facts and definitive clinical trials.  
It is actually better to first take a few steps back and consider how all microorganisms can play a role in human health by modifying the gene expression of the host (which is you).  There are four broad categories of microorganism.
Each type of microorganism can be countered by a matching category of pharmaceutical.

·        Antibacterials/antibiotics for bacteria

·        Antifungals to kill or prevent further growth of fungi

·        Antivirals to minimize (but often not eradicate) viruses

·        Antiparasitics to kill parasites  (protists)

All of the above categories of microorganism can affect the expression of multiple genes. By either up or down-regulating important genes at critical times during development, long lasting effects can be created, or there may be just transient effects.
Changes in gene expression likely play a role in many neurological conditions and in particular in what I call “flare-ups”, for example in autism, PANS, PANDAS and indeed schizophrenia.
Not all changes in gene expression are bad. The TSO parasites that do seem to help some people’s autism, by down regulating their immune response, very likely are modifying the host’s gene expression, which then reduces their immune response. This is the mechanism developed by the parasite to protect itself from the host (you) and ensure it is not eradicated.
Steroids affect the expression of multiple genes. When a bacteria of virus triggers PANDAS/PANS the positive effect of steroid therapy may well be by “resetting” the expression of certain important genes.  Here again, even though PANDAS/PANS is now treated clinically in the US, much remains unknown.
For those interested, earlier this summer revised treatment guidelines were published for PANDAS/PANS.

In "
Part I–Psychiatric and Behavioral Interventions," Margo Thienemann, MD, Stanford University and coauthors present consensus guidelines for treating the psychiatric and behavioral symptoms of children with PANS/PANDAS. Symptom improvement is aimed at decreasing suffering, improving functioning, and making it easier for the children to adhere to therapeutic interventions.

In "
Part II–Use of Immunomodulatory Therapies," Jennifer Frankovich, MD, and coauthors provide recommendations to help guide the use of therapies targeting the neuroinflammation and post-infectious autoimmunity that are common in PANS-PANDAS.

In “
Part III–Treatment and Prevention of Infections," Michael Cooperstock, MD, MPH, University of Missouri School of Medicine (Columbia) and coauthors representing the PANS PANDAS Consortium, present a consensus guideline for managing the infection components of these neuropsychiatric conditions.

There is research on what virus/bacteria affects which specific gene, but this area of science is in its infancy.
MS (Multiple Sclerosis) a condition that features faulty remyelination, is likely a much simpler condition than autism and yet nobody knows for sure what causes it. It has been suggested that a virus may be the trigger of at least some types of MS, but researchers are decades away from proving anything. So when it comes to microorganisms and autism, it is mainly a case of speculation and the odd N=1 case study. 

Viral triggers of multiple sclerosis 


The relationship between infections and autoimmune diseases is complex and the mechanisms by which infectious pathogens could trigger MS are likely dynamic, i.e., they might change over time and not be mutually exclusive. Epidemiological observations indicate that viral infections could contribute to MS development not only as triggers of disease exacerbations but also as etiological agents, i.e., long before the disease becomes clinically apparent. The two- to three-folds increased risk of developing MS among individuals with history of IM compared with subjects who acquired EBV without symptoms, the almost universal seropositivity for EBV in adults and children with MS, and the steep and monotonic increase in MS risk with increasing titers of antibodies to EBV in apparently healthy adults could suggest that EBV infection is causally linked to MS development. The mechanisms responsible for this association are far from understood. Moreover, the incidence of IM in Western countries (≥ 5%)  exceeds the prevalence of MS in comparable populations (0.1%) by far (more than 50-fold) suggesting that yet unidentified genetic and/or additional environmental factors determine whether symptomatic EBV infection indeed predisposes to MS.

Although one particular MS-causing agent might still be discovered, current data suggest that multiple infections along with noninfectious environmental factors trigger the development of MS. These factors are likely ubiquitous, i.e., highly prevalent in the general population, and they require a permissive genetic background that predisposes for MS development. Future studies investigating infectious pathogens in a complex and heterogenous disease such as MS will benefit from careful and detailed clinical, pathological, and neuroimaging-based patient characterizations and from reproducibility in different study populations. In addition, novel humanized animal models of autoimmune diseases that are simultaneously permissive for viral pathogens which usually infect only humans  should allow investigation of specific aspects of host–pathogen interactions during autoimmune CNS inflammation in vivo. The integration of these data might eventually allow us to better define the role of viruses in the etiology and pathogenesis of MS and how virus–host interactions could be targeted for MS therapy.  

The ubiquitous human herpesvirus 6 may play a critical role in impeding the brain's ability to repair itself in diseases like multiple sclerosis. These findings may help explain the differences in severity in symptoms that many people with the disease experience
What is still not fully understood is the relationship between the extent of the viral infection in the brain and the severity of diseases like multiple sclerosis and other demyelinating diseases such as leukodystrophies and Vanishing White Matter disease. For example, do the number of infected cells need to reach a certain threshold before OPC function is impeded? Are individuals who have congenital HHV6 more vulnerable to severe forms of these diseases?
"More research is needed to understand by which mechanisms the virus impedes the function of OPCs and what impact this has on the progression of these diseases," said Mayer-Proschel. "But it is clear that HHV6, while not necessarily the cause of demyelinating diseases, is limiting the ability of the brain to repair damage to myelin thereby potentially accelerating the progression of these diseases."  

Mainstream and “Alternative” Research  
Not all published research fits with the current mainstream scientific consensus. The mainstream is clearly moving towards the realization that all kinds of things can affect gene expression. One currently fashionable area is the gut microbiota, as in this article:-

Some researchers develop hypotheses that go much further, like this one regarding autism’s elder brother, schizophrenia.


Many genes have been implicated in schizophrenia as have viral prenatal or adult infections and toxoplasmosis or Lyme disease. Several autoantigens also target key pathology-related proteins. These factors are interrelated. Susceptibility genes encode for proteins homologous to those of the pathogens while the autoantigens are homologous to pathogens' proteins, suggesting that the risk-promoting effects of genes and risk factors are conditional upon each other, and dependent upon protein matching between pathogen and susceptibility gene products. Pathogens' proteins may act as dummy ligands, decoy receptors, or via interactome interference. Many such proteins are immunogenic suggesting that antibody mediated knockdown of multiple schizophrenia gene products could contribute to the disease, explaining the immune activation in the brain and lymphocytes in schizophrenia, and the preponderance of immune-related gene variants in the schizophrenia genome. Schizophrenia may thus be a “pathogenetic” autoimmune disorder, caused by pathogens, genes, and the immune system acting together, and perhaps preventable by pathogen elimination, or curable by the removal of culpable antibodies and antigens.

And this one by the same author:-

Herpes simplex virus 1 (HSV-1) can promote beta-amyloid deposition and tau phosphorylation, demyelination or cognitive deficits relevant to Alzheimer's disease or multiple sclerosis and to many neuropsychiatric disorders with which it has been implicated. A seroprevalence much higher than disease incidence has called into question any primary causal role. However, as also the case with risk-promoting polymorphisms (also present in control populations), any causal effects are likely to be conditional. During its life cycle, the virus binds to many proteins and modifies the expression of multiple genes creating a host/pathogen interactome involving 1347 host genes. This data set is heavily enriched in the susceptibility genes for multiple sclerosis (P = 1.3E-99) > Alzheimer's disease > schizophrenia > Parkinsonism > depression > bipolar disorder > childhood obesity > chronic fatigue > autism > and anorexia (P = 0.047) but not attention deficit hyperactivity disorder, a relationship maintained for genome-wide association study data sets in multiple sclerosis and Alzheimer's disease. Overlapping susceptibility gene/interactome data sets disrupt signalling networks relevant to each disease, suggesting that disease susceptibility genes may filter the attentions of the pathogen towards particular pathways and pathologies. In this way, the same pathogen could contribute to multiple diseases in a gene-dependent manner and condition the risk-promoting effects of the genes whose function it disrupts.

Back to Autism
As we have seen previously in this blog, autism is usually polygenic, meaning very many different genes are affected. This does not mean that anything is necessarily defective in those genes, it just means those genes are either over or under-expressed, this means you end up with either too much, or too little, of whatever that gene makes.
So for a polygenic condition, where in one person hundreds of your 22,000 individual genes are likely over or under-expressed, we really do not want anything to come along and further miss-express critical genes.
Many genes are inter-related and so miss-expression of one can trigger a wave of further effects. This can be either good or bad.
The science is still in its infancy, so it will be many decades before it is translated into medicine, but we can certainly already say what may be happening.
The interactome is a relatively new word to describe the whole set of molecular interactions in a particular cell.
 For example, the well-known bacteria H.pylori that can cause stomach ulcers:- 

Over 1,200 interactions were identified between H. pylori proteins, connecting 46.6% of the proteome.

Just this one common bacterium affects half of the entire set of proteins expressed by a genome (the so called proteome).
So we should not be surprised if some bacteria or viruses have a bad, or indeed good, effect on autism.
This also bring us back to the idea of the holobiont and hologenome, which was introduced in an earlier post. The idea is that what really matters in human health is not just your genome, but the totality of what surrounds you, so that means everything living in you, on you and around you. That includes bugs, bacteria and also those of your pet dog.
All of these factors influence how your genes are expressed. During evolution your body has got used to things and if you make rapid changes, you may indeed upset the balance. So while chlorinating water may have an overall good effect, by killing all those bacteria your body had been expecting, there may be some negative effects. Humans evolved living close to animals, be it dogs or farm animals. We saw earlier that pregnant mothers who live with pets produce children with a lower incidence of asthma.
We also reviewed the hygiene hypothesis, which basically says that a bit of dirt is good for you.
So this post, rather than narrowing things down, really broadens them out.  Everything affects everything.  If you rock the evolutionary boat, don’t be surprised if strange things happen.
Taking Somali refugees to live in Sweden increased their incidence of autism. Is that really a surprise? Recall the Somali autism clusters in Sweden and San Diego.
Apparently, the Amish in the US have a low prevalence of autism. Is that really a surprise?  One reader recently suggested sending autistic people to live with the Amish, as a therapy. The possibly effective therapy would have been to send the parents to live with the Amish for a couple of years before the child was born.
So perhaps we should consider much autism, and indeed conditions like asthma, as collateral damage from modern living?  Life expectancy has risen, infant mortality has been greatly reduced, but the downside is that we now have much more autoimmune disease and that includes autism.

Autism and Microorganisms
Now back to autism and the four categories of microorganism.
Can parasites cause autism? Actually we know they can; for example cerebral malaria can result in it. But how often is this case? Probably very rarely.
Can fungi cause autism? Perhaps, but we know from many examples (including in the comments on this blog) that some fungi can make autism worse.  Is the fungus candida albicans growing in the intestines really an issue in most autism? I seriously doubt it, but oral thrush/candidiasis caused by inhaled steroids does seem to make autism worse and is reversible by removing the fungus. The effect seems more likely to be from the candida than the steroid, since inhaled steroids only mildly enter the bloodstream.
Can bacteria cause autism? Well streptococcus bacteria can cause OCD and cognitive impairment (PANDAS).
Can a virus cause autism? Antonio Persico, one of the more serious autism researchers, has suggested that some autism may be caused by polyomaviruses transmitted at conception from father to mother.
https://spectrumnews.org/news/could-a-virus-cause-autism/

Can the rubella virus cause autism? Some serious people do see a possibility, even in people who have been vaccinated.

These both remain controversial hypotheses; but can viruses cause flare ups in autism, later in life? This is also controversial, but I think quite plausible.  It all depends which genes the virus causes to get miss-expressed.
Enough is known to say that odd changes in autism may potentially be triggered by the appearance of specific types of microorganism, but quite possibly most microorganisms have little, or no, negative effect in most people. So it is not a case of all viruses/bacteria will make autism worse, but it is likely true that some may have the potential to do so.
In trying to figure out possible causes of autism flare-ups, due consideration should be given to microorganisms.  This is another case of personalized medicine, with all its potential pitfalls.
The big risk is potentially becoming obsessed with non-existing bacteria, viruses, fungi or parasites.  


Back to Antivirals and Autism 
Finally we come back to where the original idea for this post came from; is there any basis of the use of antiviral drugs to treat autism?
DAN-type doctors do prescribe the antiviral drugs Valtrex, Famvir or Acyclovir.


Antiviral drugs do not destroy their target virus they just inhibit its development.
Most of the antiviral drugs now available are designed to help deal with HIV, herpes viruses, the hepatitis B and C viruses, and influenza A and B viruses.
You identify a virus by looking for antibodies to that specific virus in the blood. You can test for antibodies that suggest if the infection is new and active, called IgM antibodies and you can test for antibodies that show the infection occurred sometime in the past, called IgG antibodies.
You would need to know which virus to test for, the common ones are:-

HSV 1:  Herpes Simplex Virus 1 causes canker sores in the mouth

HSV 2: Herpes Simplex Virus 2 causes genital herpes.

HHV 6: Human Herpes Virus 6 is commonly known as Roseola virus

EBV: Epstein-Barr Virus, causes the illness known as infectious mononucleosis

Measles

Rubella  


“We’re not saying that HSV-2 is responsible for infecting the [fetal] brain and causing autism,” stresses senior author Ian Lipkin, an infectious disease expert and epidemiologist at Columbia. Indeed, fetal infection with HSV-2 is so serious that it frequently leads to miscarriages or stillbirths. Rather, Lipkin suspects that HSV-2 is just one among many environmental insults that, when they arrive at a vulnerable point in fetal development in women predisposed to damaging reactions, may trigger ASD in the fetus.” 

Conclusion: Rate of contact with HSV1 and HSV2 assessed by the mean of detection of specific antibodies was similar between children with ASD and healthy controls.

Conclusion: Levels and seropositivity rate of antibodies to HHV-6 and HHV-8 do not differ between children with ASD and controls.
CONCLUSION: Titre and seropositivity rate of antibodies to CMV and EBV are similar between children with ASD and healthy controls.


Valtrex 
Valtrex seems to be the antiviral most commonly prescribed in autism.  This is an off-label use, meaning Valtrex is not approved to treat autism.  Valtrex is active against most species in the herpesvirus family. In descending order of activity:

So we might assume the people with autism who respond to Valtrex might have one of the above, or similar, viruses. Unless Valtrex has some other modes of action, unrelated to being an anti-viral, which remains a possibility. 

Mitochondrial Disease and Viral Infections
Since this post is already full of speculation, I will add some more. Some people say that their child’s mitochondrial disease was preceded by a viral infection, so how likely is it that a virus can trigger mitochondrial disease and then autism?  Again, this is not something anyone can prove, one way or the other, but it does look like your mitochondria are particularly vulnerable to viruses.
The virus will exploit the mitochondria to further its own development, perhaps in doing so, in some people with a pre-disposition, this triggers a process to chronic mitochondrial dysfunction.  Read the papers below for more on this subject.


Highlights


Mitochondrial dynamics influences mitochondrial and cellular functions.
Mitochondrial dynamics is affected during viral infections.
Viruses exploit mitochondrial dynamics and mitophagy to benefit infectious process.
Virus-altered mitochondrial dynamics determines the outcome of infection.
Disruption of mitochondrial dynamics promotes viral pathogenesis.

If a virus can trigger mitochondrial disease, as we have seen a vaccination can, is there any possible merit in using antivirals years later?
Is there merit treating regressive autism, which is likely to be mitochondrial disease, immediately with antiviral drugs?
Is there merit treating autism flare-ups, that do not respond to PANDAS/PANS therapies, with antiviral drugs?
Is there merit treating MS (multiple sclerosis) immediately on diagnosis with antiviral drugs? Would MS flare-ups respond to antivirals?

My take
If I was to develop MS tomorrow, given there is currently no cure, I think I might want to try an antiviral, just in case it might actually do some good.
My son with classic autism did have a PANDAS-like regression last year, with sudden onset OCD and strange verbalizations. It all went away after a couple of weeks, having been treated as a PANDAS flare-up, as documented in an old post on this blog. If after a viral infection he developed a sudden onset regression I would certainly reread this post.
Readers of this blog with a clear case of mitochondrial disease might want to check for the commonly implicated viruses, since if one was never suppressed this might be something to consider.
So do antivirals have a place in treating autism?  There is no hard evidence to support their use, but I would not at all be surprised if a minority do genuinely benefit. I think the most likely group might be those who have a sudden regression from near typical. As with PANDAS/PANS, the sooner the treatment commences, the better the likely outcome. 
Could antivirals help control flare-ups that can occur in those already with autism? They could well help; ideally you would confirm the presence of the virus first.   

Conclusion
I recently watched an expert clinician talking about irritable bowel syndrome (IBS); he was very open about his opinion that science likely only understands about 30% of the disorder. When it comes to autism I think science may be only at the 10% mark. As a result you have to be very careful about saying anything definitive.
We know that very many things contribute to the prevalence of autism.  It looks more than likely that viruses, bacteria, fungi and parasites may, on occasion, play a role in some people’s autism.
But, just like we know that in some people vaccination can trigger mitochondrial disease and result in an autism diagnosis, this does not mean it is a common cause of autism. Vaccinations have saved hundreds of millions of lives, but it has long been known that they can have side effects and that is why there is a large industry-funded compensation scheme in the US.
So while parasites can in some circumstances lead to autism, this does not mean feeding bleach to children with autism is a clever idea. Nor does filling them with antibiotics to treat a non-existing bacteria.
You can see why mainstream medicine is not eager to treat autism.
Nonetheless, applying that meagre sounding 10% of understanding can yield results, when applied with caution.










Monday 8 May 2017

Pan-agonists of PPARs and PGC-1α in Mitochondrial Disease, Autism and Sport


Today’s post should be of interest to those concerned about mitochondrial disease and mTOR.


mTOR is a very important signaling cascade that often dysfunctional in autism. Many aspects of autism and its comorbidities can be traced back to mTOR.
The going is easier with a PPAR pan-agonist 

mTOR integrates the input from upstream pathways, including insulin, growth, and amino acids.   mTOR also senses cellular nutrient, oxygen, and energy levels. The mTOR pathway is a central regulator of metabolism and physiology, with important roles in the function of tissues including liver, muscle, adipose tissue, and the brain.  It is dysregulated in human diseases, such as diabetes, obesity, certain cancers and indeed autism.

One important process affected by mTOR is the creation of new mitochondria in your cells.  Each cell has many mitochondria, but in some people there are not enough and/or they may not work properly.  
In the above post we saw that Oxidative phosphorylation (or OXPHOS in short) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy.  This takes place inside mitochondria.

The five enzymes required have simplified names: complex I, complex II, complex III, complex IV, and complex V.

The most common problem in autism is a lack of complex 1, this leads to a lack in the production of energy (ATP) in cells.  In your muscles this will appear as a lack of exercise endurance and in your brain as a lack of cognitive function.

On that rather intimidating chart (below), all about mTOR, tucked away at the bottom right is PGC-1α.
Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is the master regulator of mitochondrial biogenesis.

PGC-1α may be also involved in controlling blood pressure, regulating cellular cholesterol homoeostasis, and the development of obesity.

PGC-1α is thought to be a master integrator of external signals. It is known to be activated by a many factors, including:-


·         Exercise  (gradual endurance training)


·         PPARδ , PPARγ and it was thought PPARα


·         AMPK (Metformin, or AICAR)


·         Sirt-1 (resveratrol and other polyphenolic ‎compounds)

Interestingly, massage therapy appears to increase the amount of PGC-1α which leads to the production of new mitochondria. Many autism parents believe in various massage therapies. 

Metformin is a very old drug to treat diabetes, it does activate AMPK but unfortunately it also inhibits the Complex 1 mitochondrial enzyme. This might explain why one reader of this blog found it had a negative effect in her son.  In some types of cancer metformin can be used to “starve” the cancer cells of energy and stop them proliferating.

AICAR was thought to have been used by cyclists in the 2009 Tour de France, it is a heart drug from the 1980s. It activates AMPK and increases nitric oxide production from endothelial nitric oxide synthase.













Here is the lower right part enlarged:-





  

The above chart, while complex does not give the complete picture regarding PPAR.

It appears that the type of PPAR that is needed to activate PGC-1α  is actually PPARδ  (PPAR delta). For a long time researchers thought it was PPAR α (PPAR alpha).


PGC-1 alpha induces mitochondrial biogenesis in muscle and its activity has been related to insulin sensitization. Here, we report that fibrates induce PGC-1 alpha gene expression in muscle both in vivo and in vitro. However, only activation via PPAR delta but not PPAR alpha underlies this effect. PPAR delta induces PGC-1 alpha gene transcription through a PPAR-response element in the PGC-1 alpha promoter. Moreover, PGC-1 alpha coactivates the PPAR delta-responsiveness of its own gene. A further positive autoregulatory loop of control relies on the induction of PPAR6 expression by PGC-1 alpha. These data point to a distinct value of PPARdelta rather than PPAR alpha agonists in the improvement of oxidative metabolism in muscle.



Peroxisome proliferator-activated receptors (PPARs)

There was a post in this blog a long time ago about all the PPARs. There are three types (alpha, delta and gamma) just to confuse us, sometimes delta is called beta.

  • α (alpha) - expressed in liver, kidney, heart, muscle, adipose tissue, and others
  • β/δ (beta/delta) - expressed in many tissues but markedly in brain, adipose tissue, and skin
  • γ (gamma) - although transcribed by the same gene, this PPAR through is expressed in three forms:
    • γ1 - expressed in virtually all tissues, including heart, muscle, colon, kidney, pancreas, and spleen
    • γ2 - expressed mainly in adipose tissue
    • γ3 - expressed in macrophages, large intestine, white adipose tissue.

It does seem that activating alpha, gamma and delta has potential benefit.

The PPAR alpha agonist PEA is available as a supplement and as food for medical purposes In Italy and Spain.  It has been proposed for various inflammatory and pain syndromes. A large trial at a Skoda car factory in 1972 showed that PEA was protective against flu and the common cold.


Fibrate drugs are PPAR alpha agonist drugs used to lower cholesterol. A key point here is that these drugs also activate other types of PPAR as well.
PPAR gamma agonists are widely used to treat diabetes.  They improve insulin sensitivity and decrease some inflammatory responses. They lower cholesterol.
PPAR delta has various antidiabetic effects and agonism of PPAR delta changes the body's fuel preference from glucose to lipids. Recently it was shown that PPAR delta can be activated to promote biogenesis of mitochondria.
It does appear likely that there is some interaction between the PPARs.
Using the mild PPAR gamma agonist, Sytrinol, which gives a long term cholesterol lowering effect, gives a short term cognitive and behavioral improvement in autism.
Pioglitazone is used to lower glucose levels in type 2 diabetes and is a PPAR gamma agonist.  It has been shown to have a positive effect in autism and more trials are in progress. It also binds to a lesser extent to PPAR alpha.
Our reader Maja is investigating whether Sytrinol will maintain its initial good effect when combined with a mild PPAR alpha agonist, like PEA. 

Pan-agonists of PPAR

Bezafibrate appears to be the best known “pan-agonist” of PPAR alpha, gamma and delta.

The PPARpan-agonist bezafibrate ameliorates cardiomyopathy in a mouse model of Barth syndrome 

   
Bezafibrate as treatment option in patients with mitochondrial complex I (CI) deficiency

These results support bezafibrate as a promising treatment option for specific subgroups of patients with CI deficiency.

Less well known is the natural substance Berberine. 




The multifaceted drug Telmisartan, from a recent post, is also a pan-agonist of PPARs. It is usually quoted as being a PPAR delta agonist. 




AICAR

The drug AICAR is thought of as an AMPK activator rather than a PPAR agonist, but it does affect all three types of PPAR.

Treatment with AICAR induced gene expression of all three PPARs, but only the Ppara and Pparg regulation were dependent on AMPK.


Conclusion

It looks like some athletes, seeking an advantage, are already using the above strategies to improve their exercise endurance; having more mitochondria is of course a competitive advantage.  A list of all the substances banned in sport might be another good source of therapies not only for autism, but also dementia.
Since mitochondrial dysfunction is a feature of Parkinson’s, Huntington’s and Alzheimer’s there are some investigations ongoing. There is even a trial to perk up the mitochondria in people with Bipolar using Bezafibrate.
It is odd that Sytrinol has only a short term positive effect in most people with autism, although our reader RG’s daughter has a long term benefit. I suspect some people may need a pan-agonist, there may be some interaction/crosstalk/ feedback that we are not aware of.
It would be nice to have some data on the relative potency of Bezafibrate,  Telmisartan and Berberine across alpha, delta and gamma receptors, otherwise we are left with trial and error.
The advantage of Berberine is that it is an OTC supplement.
AICAR is also interesting.









Thursday 4 May 2017

Angiotensin II in the Brain & Therapeutic Considerations





In a previous post I suggested that another cheap generic drug (an ACE inhibitor) could potentially be repurposed to treat schizophrenia and some autism. The original idea was related more to modifying the immune/inflammatory response in the body, rather than the brain.  There is however plenty of research regarding Angiotensin within the brain and the numerous roles it plays.

Juggling - maximizing effects, while minimizing
drug interventions



You may recall in the earlier post that in both schizophrenia and autism there is elevated angiotensin II.

In the brain there are two types of angiotensin receptor, AT1 and AT2.  Their actions are opposing each other.

In many kinds of disease we would want to stimulate AT2, but inhibit AT1.

AT2 is thought to be important for cognitive function and is now a target for Alzheimer’s research.

Using an ACE inhibitor you reduce the amount of angiotensin II and so in effect inhibit both AT1 and AT2.

In theory angiotensin II should not cross the blood brain barrier (BBB), so we should be dealing with centrally produced (i.e. inside the brain) angiotensin II.  In practical terms it seems that people with high levels of angiotensin II may have a permeable BBB.

This is relevant because most ACE inhibitors do not cross the BBB, but the original ACE inhibitor called Captopril does cross the BBB.  So if a centrally acting ACE inhibitor were found to be required, it was discovered 40 years ago.

A therapy would ideally be targeted selectively at AT1 or AT2 receptors.  An AT1 blocker might treat for stress-induced disorders.  An experimental AT2 receptor agonist, called compound 21, is now available and is expected to reduce inflammation and oxidative stress.


Angiotensin II receptor AT1 antagonists are widely used drugs indicated for hypertension, diabetic nephropathy and congestive heart failure. They block effect of Angiotensin on AT1 and might be good in the brain.

We would like to increase the effect on AT2, we could do that with more Angiotensin II, but then we would make things worse with AT1.


                          Do nothing  ACE inhibitor    AT1 antagonist      AT2 agonist

Effect on AT1               none                            good                                     good                          none

Effect on AT2               none                            bad                                       none                          good



AT1 antagonists are widely available and seen as well tolerated.

AT1 antagonists appear to protect against Alzheimer’s.

The only AT2 agonist is an experimental drug called Compound 21.

The only ACE inhibitor that should affect AT2 in the brain is Captopril and so may be an unwise choice. It will reduce Angiotensin II in the brain and in the rest of the body.


Why were we interested in Angiotensin?


In the original Angiotensin post in this blog we saw that in schizophrenia and some autism, that Angiotensin II is elevated.  We also saw that:-

·        Blocking angiotensin-converting enzyme (ACE) induces those potent regulatory T cells that are lacking in autism and modulates Th1 and Th17 mediated autoimmunity.  See my last post on Th1, Th2 and Th17. 

·        In addition, Angiotensin II affects the function of the NKCC1/2 chloride cotransporters that are dysfunctional in much autism and at least some schizophrenia.

·        It should also reduce any troubling high levels of leptin, which we saw in another post is an issue in most autism

So the idea was that many broadly anti-inflammatory effects of reducing Angiotensin II might be helpful in autism.

But what about inside the brain?


Angiotensin in the Brain

Here we do get to the science, but I will start with the conclusion. We actually want more effect from the Angiotensin AT2 receptor, which should give numerous benefits, but have no means of achieving this. What we can do is make sure we do not reduce AT2 activity, this means better to use and AT1 antagonist, rather than an ACE inhibitor.

The science supporting the use of an AT agonist follows:-

In the text you will see ARB and compound 21. Both are doing good things. The suggestion is that by doing all these good things there should be improved cognitive function; this has yet to be proved in human tests.

ARB = Angiotensin Receptor AT1 Blocker

Compound 21 = Angiotensin Receptor AT2 agonist



The brain renin-angiotensin system (RAS) has been highlighted as having a pathological role in stroke, dementia, and neurodegenerative disease. Particularly, in dementia, epidemiological studies indicate a preventive effect of RAS blockade on cognitive impairment in Alzheimer disease (AD). Moreover, basic experiments suggest a role of brain angiotensin II in neural injury, neuroinflammation, and cognitive function and that RAS blockade attenuates cognitive impairment in rodent dementia models of AD. Therefore, RAS regulation is expected to have therapeutic potential for AD. Here, we discuss the role of angiotensin II in cognitive impairment and AD. Angiotensin II binds to the type 2 receptor (AT2) and works mainly by binding with the type 1 receptor (AT1). AT2 receptor signaling plays a role in protection against multiple-organ damage. A direct AT2 receptor agonist is now available and is expected to reduce inflammation and oxidative stress and enhance cell differentiation. We and other groups reported that AT2 receptor activation enhances neuronal differentiation and neurite outgrowth in the brain. Here, we also review the effect of the AT2 receptor on cognitive function. RAS modulation may be a new therapeutic option for dementia including AD in the future.






Figure 1: Possible effect of angiotensin II on neurovascular unit. AT2: angiotensin II type 2 receptor, AchR: acetylcholine receptor, BBB: blood brain barrier, and TGF-β: transforming growth factor β.







Figure 2: Effect of angiotensin II type 2 receptor signaling on cognitive function. AT2: angiotensin II type 2 receptor, ATIP: AT2 receptor-interacting protein, Id1: inhibitor of DNA binding protein 1, MMS2: methyl methanesulfonate-sensitive 2, NO: nitric oxide, SHP-1: Src homology 2 domain-containing protein-tyrosine phosphatase 1, and Ubc-13: ubiquitin conjugating enzyme 13.








Figure 3: Effect of angiotensin II on cognitive function. ACE: angiotensin converting enzyme inhibitor, AT1: angiotensin II type 1 receptor, AT2: angiotensin II type 2 receptor, and ARB: angiotensin II type 1 receptor blocker.


Continuous stimulation with angiotensin II may damage neurons via multiple cascades through AT1 receptor stimulation. On the other hand, stimulation of the AT2 receptor is expected to prevent neural damage and cognitive impairment (Figure 3). However, it is difficult to perform clinical intervention studies to confirm the results of animal studies because of the long-term progression of cognitive impairment. Moreover, in clinical practice, it is not possible to exclude the antihypertensive effect of RAS blockade on cognition in patients with hypertension. However, RAS modulation may be a new therapeutic option for dementia including AD in the future. Therefore, the hypothesis that RAS regulation affects future cognitive function should be confirmed with carefully designed clinical studies.



Which ARB (Angiotensin Receptor Blocker) for Autism?

Very many biological markers are disturbed in autism and many of them seem to be best ignored, you cannot “correct” them all.

However, there will be an underlying reason behind each one of them being disturbed.

As we saw in the recent post on metabolic syndrome, it is not uncommon to find a cascade of downstream problems that might seem to indicate a huge list of drugs.  A different approach is required, it is necessary to treat the underlying (upstream) problems and have a much shorter list of therapies.

We saw in the post on leptin that the elevated levels in autism are treatable, but is there any point?

We have a long list of other things that might be useful in autism and it would be nice to have a single therapy that might address many of them.

It appears that selecting the optimal ARB might give the opportunity to address numerous issues at once.

Telmisartan seems to have numerous potentially useful additional effects:


·        Acts as a PPAR gamma agonist, like the glitazone drugs shown effective in autism trials

·        Acts as a PPAR delta agonist, which should activate the impaired PPARδ  PGC-1α signaling pathway, and enhance mitochondrial biogenesis. This should help people with mitochondrial disease and should be evident by increased exercise endurance and, in theory, improved cognitive function.

·        Telmisartan regulates the Bcl-2 cancer gene, implicated in autism


While the effect in autism is complex, Telmisartan is already seen as a potent target for prevention and treatment in human prostate cancer

·        Telmisartan and other ARBs appear to give protection from Alzheimer’s Disease (suggested to be via its effect on PPAR gamma). Perhaps useful for young adults with Down Syndrome, where early onset Alzheimer’s is expected?


·       Telmisartan and other ARBs have a tendency to increase the level of potassium in blood. Up to 10% of people would experience mild hyperkalemia.  For people with autism taking bumetanide, this effect on potassium might actually be helpful. They would need to reduce their potassium supplementation, or might need none at all.




Telmisartan in clinical trials related to autism

As is repeatedly the case, schizophrenia research is again more advanced than autism research. A quick check showed this:-



This is a 12-week, randomized, double-blinded, placebo-controlled trial of telmisartan 80 mg/day as an adjunctive to clozapine or olanzapine therapy, in 70 schizophrenia subjects to examine telmisartan's effect on glucose metabolism, weight, food intake, resting energy expenditure, and body composition. In addition, the study will examine insulin's effects on psychopathology and cognition.



Conclusion

We currently have no possibility of something like Compound 21, but Telmisartan looks very interesting and it would nice if those psychiatrists who have trialed it in schizophrenia would do the same in autism.  

It looks like the beneficial effects should come at a lower dose than that used to lower blood pressure. In the schizophrenia trial I think they used a higher dose (80mg) than necessary, I suppose they wanted to maximize their chance of success.  In order to minimize any possible negative effects, I would suggest the psychiatrists trial 20mg in youth with autism.

There will be a post on PPAR delta and mitochondrial disease, because there are at least two other ways to target mitochondrial disease in this way, if you do not like Telmisartan.  There is the cheap drug Bezafibrate and the supplement berberine.