Garlic in Autism – Miscreant Microglia? ACE inhibition? or even Nitric Oxide?

Many people avoid garlic because it gives you bad breath, but if you eat enough of it, it can be a potent drug.

There is a substantial amount of research about garlic and general health - it is consistently positive. However, there is an odd resistance to tell people about it.  A good example is this quote from the website of the UK’s National Health Service.

“Studies using high concentrations of garlic extracts have been associated with improved blood circulation, healthier cholesterol levels and lower blood pressure, all of which reduce the risk of cardiovascular disease. However, current evidence does not support the use of garlic supplements to improve health.”

Which sounds like “garlic is really good for you, but don’t eat it”.

Garlic has numerous different modes of action that have a potential health benefit, the best known relate to your heart and circulation, but there are others. 

Garlic and Neurological Conditions with Activated Microglia

There is recent research showing positive effects on the activated microglia.  Activated microglia, the brain’s immune cells, is a feature of autism and other diseases, like Alzheimer’s.

Some people try and treat activated microglia in autism using therapies like:-

·        Minocycline

·        Ibudilast

Some researchers use garlic to try to minimize the damage caused by activated microglia.

They tend to use capsules that contain aged garlic.  It is important not to cook it and there is a difference between fresh garlic, aged garlic and steamed garlic. 

Table 1. Principal Organosulfur Compounds in Commercial Garlic Preparations
Product	Principal Organosulfur Compounds	Delivers allicin-derived compounds?
Fresh garlic cloves	Cysteine sulfoxides (Alliin) γ-glutamylcysteines	Yes, when chopped, crushed, or chewed raw. Minimal, when garlic cloves are cooked before crushing or chopping.
Powdered garlic (tablets)	Cysteine sulfoxides (Alliin) γ-glutamylcysteines	Varies greatly among commercial products. Enteric-coated tablets that pass the USP allicin release test are likely to provide the most.
Steam distilled garlic oil (capsules)	Diallyl disulfide Diallyl trisulfide Allyl methyl trisulfide	Yes
Garlic oil macerate (capsules)	Vinyldithiins Ajoene Diallyl trisulfide	Yes
Aged garlic extract™ (tablets or capsules)	S-Allylcysteine S-Allylmercaptocysteine S-1-Propenylcysteine	Minimal

  

Source: -http://lpi.oregonstate.edu/mic/food-beverages/garlic

  

Benefits Of Garlic Extract May Protect Brain From Inflammation, Diseases Like Alzheimer's

Now, a new study finds that one of these compounds, called FruArg, may protect the brain from age-related disease like dementia and Alzheimer’s.

As a carbohydrate derivative of garlic, there’s a relatively high concentration of FruArg in aged garlic extract (AGE), the authors wrote — AGE is typically sold as supplements. Looking at isolated FruArg’s impact on brain cells, researchers from the University of Missouri found it could protect brain cells from an overexcited immune response caused by environmental factors like pollution and smoking, as well as normal aging, brain injuries, and drinking lots of alcohol.

“Microglia are immune cells in the brain and spinal cord that are the first and main line of defense in the central nervous system,” said lead author Zezong Gu, an associate professor of pathology and anatomical sciences at the university’s School of Medicine. “Unlike other mature brain cells that seldom regenerate themselves, microglial cells respond to inflammation and environmental stresses by multiplying. By massing themselves and migrating toward an injury site, they are able to respond to inflammation and protect other brain cells from destruction.”

But microglia also tread a line between benefiting the body and harming it, protecting only to an extent. A byproduct of their function is nitric oxide, a free radical. And when a lot of microglia are produced, so are nitric oxide molecules, which can lead to oxidative stress and inflammation within the brain and nervous system. As we’ve all heard before, however, antioxidants fight oxidative stress, and in this case, that antioxidant compound is FruArg. 

For their study, Gu and his colleagues applied stress to a cell model of microglial cells and then added FruArg to them once nitric oxide concentrations rose. They found the microglial cells “adapted to the stress by reducing the amount of nitric oxide they produced.” What’s more, FruArg also promoted the production of antioxidants, which then went on to protect and heal other brain cells. “This helps us understand how garlic benefits the brain by making it more resilient to the stress and inflammation associated with neurological diseases and aging,” Gu said. 

Full study:- 

Proteomic analysis of the effects of aged garlic extract and its FruArg component on lipopolysaccharide-induced neuroinflammatory response in microglial cells.

Collectively, these results suggest that AGE and FruArg attenuate neuroinflammatory responses and promote resilience in LPS-activated BV-2 cells by suppressing NO production and by regulating expression of multiple protein targets associated with oxidative stress. 

Effects of aged garlic (AGE) extract and FruArg on gene expression and signaling pathways in lipopolysaccharide-activated microglial cells 

These effects could be modulated by treatment with both AGE and FruArg. These findings suggests that AGE and FruArg are capable of alleviating oxidative stress and neuroinflammatory responses stimulated by LPS in BV-2 cells.

  

Evaluating the Anti-Neuroinflammatory Capacity of Raw and Steamed Garlic as Well as Five Organosulfur Compounds

Abstract

: The anti-neuroinflammatory capacities of raw and steamed garlic extracts as well as five organosulfur compounds (OSCs) were examined in lipopolysaccharide (LPS)-stimulated BV2 microglia. According to those results, steaming pretreatment blocked the formation of alliinase-catalyzed OSCs such as allicin and diallyl trisulfide (DATS) in crushed garlic. Raw garlic, but not steamed garlic, dose-dependently attenuated the production of LPS-induced nitric oxide (NO), interleukin-1β (IL-1β), tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein-1 (MCP-1). DATS and diallyl disulfide at 200 and 400 μM, respectively, displayed significant anti-neuroinflammatory activity. Meanwhile, even at 1 mM, diallyl sulfide, S-allyl cysteine and alliin did not display such activity. Inhibition of nuclear factor-κB activation was the mechanism underlying this protective effect of raw garlic and DATS. Analysis results indicated that the anti-neuroinflammatory capacity of raw garlic is due to the alliin-derived OSCs. Importantly, DATS is a highly promising therapeutic candidate for treating inflammation-related neurodegenerative diseases.

As expected, raw garlic extract inhibited NO, proinflammatory cytokine, and chemokine production by through suppression of NF-κB activation in LPS-activated BV2 microglia; it also had a potent anti-neuroinflammatory capacity. Additionally, steaming pretreatment abolished both the anti-neuroinflammatory capacity and alliin-derived OSCs formation of garlic simultaneously. In sum, this study demonstrates that alliinase catalysis and chemical transformation are essential for the formation of active OSCs, which are responsible for the anti-neuroinflammatory capacity of garlic. Based on above, it is suggested that consumers to crush or cut raw garlic before cooking in order to obtain more health benefits of garlic. As one of the most potent anti-neuroinflammatory components of garlic, DATS is highly promising for use as a dietary agent to prevent inflammation-related neurodegenerative disease. 

Garlic as an ACE inhibitor 

We saw in a recent post how too much angiotensin II is likely a problem in schizophrenia and some autism.  The biomarker of those affected would be high levels of IL-17a. 

Targeting Angiotensin in Schizophrenia and Some Autism

There are numerous references in the literature to garlic being an ACE inhibitor, which will reduce the level of angiotensin II and hence IL-17 and IL-17a. 

Garlic extract reduces serum angiotensin converting enzyme (ACE) activity in nondiabetic and streptozotocin-diabetic rats. 

Although garlic extract administration had no significant effect on serum glucose, it significantly strongly decreased the serum ACE activity. ACE activity was higher in diabetic than nondiabetic rats, but in diabetic animals treated with garlic extract, the elevation of ACE activity did not occur. These results suggest that garlic extract might have value as ACE inhibitor to prevent some vascular complications of diabetes mellitus.

So perhaps some people with autism, who respond to garlic are actually not feeling the microglia effect, but actually the angiotensin II reducing effect. 

Potent activation of nitric oxide synthase by garlic: a basis for its therapeutic applications. 

Activation of calcium-dependent nitric oxide synthase and the subsequent production of nitric oxide is probably the most novel mechanism yet claimed by which garlic can exert its therapeutic properties.

   

Conclusion  

Garlic has numerous health benefits and different types of processing lead to very different chemical compositions.  So it does depend how you take your garlic.

Does any type of garlic provide a benefit in any type of autism? 

For one reader fresh garlic is effective in treating autism, whereas aged garlic is not; this is not what she expected. This would of course suggest something about its mode of action. 

Perhaps some people are actually benefiting from a reduction in angiotensin II.  Or maybe it is production of nitric oxide?

There are actually other natural ACE inhibitors that you might be using by accident.

People trying to make tasty drinkable sulforaphane, using the Australian mixture of broccoli and pomegranate powders, are actually also making an ACE inhibitor.  

Effect of pomegranate juice on Angiotensin II-induced hypertension in diabetic wistarrats

The results suggest that the PJ extract could prevent the development of high blood pressure induced by Ang II in diabetic rats probably by combating the oxidative stress induced by diabetes and Ang II and by inhibiting ACE activity.

Pharmacological review on Natural ACE inhibitors 

All we can say is some people with autism respond to specific types of garlic, but nobody can be sure what the mode of action is; there are several possible credible explanations.  

Primary and Secondary Dysfunctions in Autism - plus Candesartan

Sometimes the secondary event can completely overshadow the primary event.  
The above relates to dust explosions (in large silos containing grain, sugar etc.) rather than autism.

As we continue to investigate the science behind autism and associated possible therapies, it is becoming necessary to introduce some further segmentation.

I have referred to autism “flare-ups” many times, but even that term means very different things to different people.

We now have many examples of autism treatments (NAC, Bumetanide etc), once effective, suddenly stopping working in certain people.  This needs explaining.

We know from the research that in most cases, autism is caused by multiple “hits”, only when taken together do they lead to autism.

We also see the “double tap” variety of autism, when relatively mild autism later develops into something more serious, following some event, or trigger.  

Thanks to the internet, we know have numerous n=1 examples of certain drugs showing a positive effect in some people.  You do have to discount all those people trying to sell you something, or support the cause of others trying to sell you something.  We also have full access to all those people who have patented their clever ideas, although 99% never develop them.

Within all this information there are some very useful insights, which can help further our understanding of autism

Candesartan

A case in point is Candesartan, which one reader of this blog brought to my attention, in the comment below.  This drug is used to treat high blood pressure and is often combined with a diuretic.

A very recent study relating to neurodegenerative disease and Parkinson's especially:

http://www.sciencedaily.com/releases/2015/05/150512150022.htm

discusses the use of a new drug as well as another blood pressure drug sometimes used in conjunction with Bumetanide called Candesartan. Their goal in this study was to explore how to attenuate chronic microglial activation (a hallmark of autism) by targeting toll-like receptors TLR1 and TLR2 via these two drugs.

Candesartan also modulates NKCC2 activity:

http://www.ncbi.nlm.nih.gov/pubmed/18305093

which is interesting considering the original cited research above deals with attenuating microglial activation, rather than modulating the chloride levels within GABA inhibitory neurons as Bumetanide does.

Note that Bumetanide affects both NKCC1 and NKCC2 transporters.  NKCC1 is present in the brain at birth, but should not be present in the adult brain.  However, it appears to remain in a large sub-group of those with autism, causing GABA to remain excitatory.  NKCC2 is found specifically in the kidney, where it serves to extract sodium, potassium, and chloride from the urine so that they can be reabsorbed into the blood

This drug is, along with Minocycline, is one of the few that is known to have an effect on microglial activation.

In a clinical trial, Minocycline was shown to have no effect on autism.

I do feel this kind of assessment is too simplistic; so I was interested to see the actual effect of Candesartan in autism, albeit with n=1.

Conveniently somebody has filed a patent for the use of Candesartan in autism.  Within the document is the n=1 case report of its effect.

Example of treatment with Candersartan in autism

[00047] A 16 year old boy with autism was evaluated for behavioral management. He was frequently aggressive, primarily directed to himself but to others as well. These episodes were usually unprovoked but would also occur when his parents attempted to re direct him. The child was essentially non verbal except for echolalia. His comprehension to verbal re direction was limited, making non pharmacological interventions to his aggression limited.

[00048] His neurological exam was otherwise normal.

[00049] An MRI, EEG were normal. Routine studies, including examination for fragile x and other metabolic disorders were negative.

[00050] Prior medication trials included anti convulsants which were without benefit and atypical neuroleptics, which resulted in weight gain and unsatisfactory effects on behavior.

[00051] After obtaining consent from his parents, Candesartan was started. An initial dose of 8 mg resulted in significant attenuation of aggressive behavior. Blood pressure remained stable. After 2 weeks, the dose was raised to 16 mg. Further improvement in aggression was noted with no adverse lowering of blood pressure.

[00052] The patient has remained on Candesartan with beneficial anti aggression effects being maintained over one year.

[00053] A preferred dose found by the inventor to treat autism is approximately O.lmg/kg. In children, a liquid form may be used.

So we can conclude from this that in a non-verbal 16 year old boy with autism, with significant aggressive tendencies, this drug successfully reduced aggression.  Since he was on the drug for a year, there were no other major changes, such as language or cognitive function, otherwise they would surely be mentioned to support the patent.

I can of course look further into why Candesartan might have been effective.

Our blog reader suggested this research:-

Unraveling mystery of a-synuclein inneurodegenerative disease and reversing its course

"The real job of microglia is to keep the brain healthy by getting rid of pathogens as well as cellular debris," says Maguire-Zeiss, "However, in a diseased state microglia can become chronically activated, leading to a continuous onslaught of inflammation which is damaging to the brain."

In this study, the Maguire-Zeiss lab found that only a certain size structures of misfolded α-synuclein can activate microglial cells -- normal protein and even smaller forms of misfolded α-synuclein cannot. Then the researchers sought to discover precisely how microglia responded to misfolded α-synuclein; that is, which of its many "pattern recognition receptors" reacted to the toxic protein.

Microglia use many different pattern recognition proteins, called toll-like receptors (TLR), to recognize potential threats. The investigators found that misfolded α-synuclein caused TLR1 and TLR2 to come together into one complex (receptor), creating TLR1/2. They traced the entire molecular pathway from the protein's engagement of TLR1/2 at the cell surface to the production of inflammatory molecules.

Then Maguire-Zeiss and her team tested a drug, developed by researchers at the University of Colorado, which specifically targets TLR1/2. They also tested the hypertension drug candesartan, which can target TLR2. Both agents significantly reduced inflammation.

I found some other possible explanations:-

Angiotensin II AT1Receptor Blockade Ameliorates Brain Inflammation

Brain inflammation has a critical role in the pathophysiology of brain diseases of high prevalence and economic impact, such as major depression, schizophrenia, post-traumatic stress disorder, Parkinson's and Alzheimer's disease, and traumatic brain injury. Our results demonstrate that systemic administration of the centrally acting angiotensin II AT₁ receptor blocker (ARB) candesartan to normotensive rats decreases the acute brain inflammatory response to administration of the bacterial endotoxin lipopolysaccharide (LPS), a model of brain inflammation. The broad anti-inflammatory effects of candesartan were seen across the entire inflammatory cascade, including decreased production and release to the circulation of centrally acting proinflammatory cytokines, repression of nuclear transcription factors activation in the brain, reduction of gene expression of brain proinflammatory cytokines, cytokine and prostanoid receptors, adhesion molecules, proinflammatory inducible enzymes, and reduced microglia activation. These effects are widespread, occurring not only in well-known brain target areas for circulating proinflammatory factors and LPS, that is, hypothalamic paraventricular nucleus and the subfornical organ, but also in the prefrontal cortex, hippocampus, and amygdala. Candesartan reduced the associated anorexic effects, and ameliorated associated body weight loss and anxiety. Direct anti-inflammatory effects of candesartan were also documented in cultured rat microglia, cerebellar granule cells, and cerebral microvascular endothelial cells. ARBs are widely used in the treatment of hypertension and stroke, and their anti-inflammatory effects contribute to reduce renal and cardiac failure. Our results indicate that these compounds may offer a novel and safe therapeutic approach for the treatment of brain disorders.

However the underlying mechanism may indeed be (yet again) activating PPAR γ.

Involvement of PPAR-γ in the neuroprotective and anti-inflammatory effects of angiotensin type 1 receptor inhibition: effects of the receptor antagonist telmisartan and receptor deletion in a mouse MPTP modelof Parkinson's disease


This paper suggests that the effect of Candesartan on microglia is :-


"Several recent studies have shown that angiotensin type 1 receptor (AT1) antagonists such as candesartan inhibit the microglial inflammatory response and dopaminergic cell loss in animal models of Parkinson's disease. However, the mechanisms involved in the neuroprotective and anti-inflammatory effects of AT1 blockers in the brain have not been clarified. A number of studies have reported that AT1 blockers activate peroxisome proliferator-activated receptor gamma (PPAR γ). PPAR-γ activation inhibits inflammation, and may be responsible for neuroprotective effects, independently of AT1 blocking actions."

Primary Autism Dysfunctions

I define Primary Autism Dysfunctions as those core dysfunctions that are always present.

So in the case of Monty, aged 11 with ASD, the primary dysfunctions include:-

·        GABA_A dysfunction, due to over expression of NKCC1,  leading to excitatory imbalance

·        Oxidative stress

In some other people the primary dysfunctions are quite different:-

·        Mitochondrial disease

·        etc...

I think that most aggressive behavior resulting from these dysfunctions can be traced back to communication problems and frustration.  So if the person is non-verbal and cannot get what he/she wants, aggression may follow; or if the person has pain and cannot understand it or seek help he may lash out at his care giver.

Secondary Autism Dysfunctions

I define Secondary Autism Dysfunctions as additional dysfunctions that can appear and disappear over time, these are my "flare-ups".

These dysfunctions can be more disabling that the Primary Autism Dysfunctions and it appears these are the dysfunctions that may trigger un-prompted self-injury and other random aggression.

These secondary dysfunctions can be so strong that they completely outweigh the primary dysfunction, giving the effect that the treatment for the primary dysfunction has “stopped working”.

It appears that many  Secondary Autism Dysfunctions are linked to an “over activated immune system”.  It does appear that from the research that activated microglia is an expression of this immune state and we saw one researcher calling the microglia the brain's “immunostat”. 

So in the case of Monty, aged 11 with ASD, the secondary dysfunctions are:-

·        over activated immune system / activated microglia

·        mast cell degranulation as a trigger

·        Il-6 from dissolving milk teeth as a trigger

·        Emotional distress (aged 8, when his long-time assistant left) as trigger (Emotional distress is known to cause oxidative stress)

In other people the secondary dysfunctions may be similar or quite different, for example:-

·        over activated immune system / activated microglia

·        leaky gut with GI problems as a trigger

·        food intolerance as a trigger

·        bacterial infection, with remission while on antibiotics, as a trigger

·        etc …

So I think the trial of Minocycline may have failed because the subjects were only affected by Primary Autism Dysfunctions.

I think the 16 year old aggressive boy in the Candersartan patent most likely had big Secondary Autism Dysfunctions.  The drug reduced microglial activation and so damped the effect of whatever his particular triggers were.

So probably Minocycline should be trialed again, but only in people with autism and regular SIB and aggression.  Success would be measured as a reduction in violent events.

Drugs targeting Primary Autism Dysfunctions should show things like:-

·        Cognitive improvement

·        Increased speech

·        Improved social interactions

·        Reduction in stereotypy

·        Reduction in anxiety (in higher functioning cases)

So I could classify my own interventions as

Primary

·        Bumetanide

·        Low dose Clonazepam

·        NAC

·        Sulforaphane (broccoli)

·        Atorvastatin

·        Potassium

Secondary

·        Verapamil

·        Sytrinol/Tangeretin PPAR-γ agonist for microglia

·        Occasional use of Ibuprofen (anti IL-6 therapy)

·        Quercetin/Azelastine/ Fluticasone Propionate for mast cells

The over activated immune system/activated microglia needs a trigger

Just like a modern plastic explosive is completely harmless to touch and needs the combination of extreme heat and shock wave from a detonator, it appears that the activated microglia, commonly found in autism, is in itself harmless, like Play-Doh, without a trigger.

But with a trigger, you probably know what can happen next.

What about all those failed clinical trials? False Negatives?

So now you not only need to match the trial therapy with the correct sub-type of autism, but you also cannot reliably trial a drug for a Primary Dysfunction, if there is an "active" Secondary Dysfunction.

This is indeed the reason why I do not try new therapies during the summer pollen season.

Perhaps this partly explains why clinical trials in autism always seem to fail.

The Role of Microglia in the Puzzle of Neuro-inflammation in Autism

Regular readers of this and similar blogs will have noticed that the human body functions in quite irrational ways.  We know why this is; we are the product of a very slow evolutionary process, rather than being a clean-sheet design like your smart phone or iPad.

As a result, nothing is ever quite as simple as it seems and at times the cleverer you are, the less likely you are to find a medical therapy effective in humans.

Such is the case with autism, inflammation and microglia.

It might seem that you can track back inflammation in autism to its “root cause”, which could appear to be those immune cells in the brain, called microglia.  We know they are “activated” in autism and we know that autism is typified by an “over-activated” immune response.

Working with the assumption that autism is a brain dysfunction, you would assume that the effective therapy should be inside the so-called blood brain barrier (BBB).

You would then just look for a potent drug that could “stabilize” the microglia/immune cells in the brain, to calm things down.  Having achieved this, you would sit back and marvel at the behavioral change and improvement in cognitive function.

This was exactly the thought process a few years ago when the US  National Institute of Mental Health (NIMH) got together with the Johns Hopkins researchers to follow up on their findings of chronic inflammation in the brains of people with autism.  Subsequent, third party, research has also confirmed that the microglial cells are “activated” in autism

Trial Description

Minocycline to Treat Childhood Regressive Autism

There is a subgroup of children with autism that appear to develop typically for a period of time, and then lose skills, or regress. A recent study by Vargas and co-workers at Johns Hopkins has demonstrated that the regressive subtype of autism is associated with chronic brain neuroinflammation as exemplified by activation of microglia and astroglia and the abnormal production of inflammatory cytokines and growth factors assayed in both tissue samples (brain banks) and CS. The authors remarked that these responses were similar to those seen in some neurodegenerative disorders such as amyotrophic lateral sclerosis, and that chronic microglia activation appears to be responsible for a sustained neuroinflammatory response that facilitates the production of multiple neurotoxic mediators. Chronic neuroglial activation could be the result of an abnormal persistence of a fetal development pattern. In this scenario neuroglial activation could play a role in initiating and in maintaining the pathology. Alternatively, neuroglial activation may only be a secondary response to the initiating causal factor(s) and not a direct effector of injury. Since neuroglial activation requires the nuclear translocation of the pro-inflammatory transcription factor NF-kappa B, and since inhibitors of NF-kappa-B with good CNS penetrance are available, the role of neuroinflammation in initiating and sustaining the autistic condition can be probed.

The antibiotic minocycline is a powerful inhibitor of microglial activation, apparently through blockade of NF-kappa-B nuclear translocation. Minocycline is neuroprotective in mouse models of amyotrophic lateral sclerosis (ALS) and Huntington's disease and has been recently shown to stabilize the course of Huntington's disease in humans over a 2-year period.

To evaluate the possibility of benefit in autistic children, we propose to conduct an open-label trial of the anti-inflammatory antibiotic minocycline, an agent that reduces inflammation by blocking the nuclear translocation of the proinflammatory transcription factor NF-kappa-B. Minocycline is Food and Drug Administration (FDA)-approved for treatment of a variety of infections and has been widely used for the treatment of adolescent acne. Minocycline is currently in phase III trials for the treatment of Huntington's disease and amyotrophic lateral sclerosis.

This proposal is for an initial 6-month, single-arm, off label, open-label study (with a 3 month extension phase offered to responders) that will evaluate dose safety and efficacy of minocycline in 10 children, ages 3 to 12 years, with a primary diagnosis of autism and a history of developmental regression. The subjects will be evaluated by a diagnostic/behavioral assessment, and the extent of neuroinflammation judged by CSF cytokine/chemokine profiles before and after the 6-month treatment. Subjects will also be given 0.6 mg/kg vitamin B6 twice a day as a prophylactic for possible minocycline induced nausea and vomiting. If the results of this feasibility study are encouraging, we expect to conduct a double-blind, placebo-controlled trial of minocycline therapy.

Nothing happens fast in the world of autism and so this six month study of 10 people (who completed the actual trial) was conceived in 2006, was actually concluded in 2013.  Here is the resulting paper:-

  

A pilot open-label trial of minocycline in patients with autism andregressive features

Conclusions

Changes in the pre- and post-treatment profiles of BDNF in CSF and blood, HGF in CSF and CXCL8 (IL-8) in serum, suggest that minocycline may have effects in the CNS by modulating the production of neurotrophic growth factors. However, in this small group of children, no clinical improvements were observed during or after the six months of minocycline administration.

Unfortunately, this study showed that a treatment, known to effectively stabilize microglial cells, had no positive effect on autism and actually seemed in some cases to make it worse.

We can conclude from this that stabilizing the microglia will not be the “holy grail” for treating autism.  Rather, the activated microglia is just one part of a complex, and only partially understood process.

Microglia as the Immunostat 

In a recent post we saw how Rodney Johnson referred to the microglia as the “immunostat” of the body.  Like the thermostat on the wall in your home central heating system.

Inflammation Leading to Cognitive Dysfunction

This is indeed an interesting analogy and might explain some of what is going on.

We saw in Johnson’s paper all the ways that the immune system outside the blood brain barrier (BBB) was able to communicate with the microglia.  We should assume that this communication works both ways; something that is usually overlooked.

In a perfectly functioning body, as in a perfectly functioning house, the immunostat/thermostat gives a good indication of the actual state/temperature, as well as the one you intended.  So if you set your room thermostat to 72 Fahrenheit / 22 Celsius  you expect the actual temperature to be 72 Fahrenheit / 22 Celsius.

However, in the real world things do not work like this.

We live in a house with very large south facing windows, a big fireplace, underfloor heating in some places and European-style hot water radiators (in the US they do have them).  So we have at least four sources of heat.  In spite of having clever German electronics to control our heating system, the thermostat in the centre of the house, by itself, is not adequate.

Something similar is happening in body and brain of people with autism, just replace temperature with inflammation.

Just as my house has multiple systems resulting in heating, the human body has numerous processes leading to “inflammation”.  Some of these inflammatory processes are interconnected and some are not.  The net result at any one time can be measured by looking at various cytokine levels, gene expression, microglial activation and numerous other things; there is no single measurable thing called “inflammation”.

There will never be a single wonder anti-inflammatory treatment.

The activated state of the microglia rather than being the ultimate target for intervention may just be a reflection of inflammation elsewhere in the body, or alternatively it may be just the result of oxidative stress in the brain.

Just like after a few years you may need to replace your wall thermostat, because it is giving false data, the clever immunostat, that may be the microglia, could have been disrupted by all that oxidative stress in the brain.  It might even be sending its proinflammatory signal in reverse, back across the BBB, to the rest of the body. Not such a crazy idea?

The future of anti-inflammatory interventions

The NIMH and Johns Hopkins would naturally be disappointed by the results of their study; but it was a study well worth doing.  Hopefully they will pursue other avenues of thought.

We already know that there are numerous ways to achieve a degree of immuno-modulatory change and that in some types of autism there can be a profound behavioral impact.

These range from simple Ibuprofen, to steroids like Prednisone; not to mention those Kv1.3 blockers and ShK-peptides.  These will likely all affect the microglia, but it is not their main mode of action.

Insights

As is often the case, there are useful insights that you can learn from a “failed” trial.

I would imagine that an autistic person with ulcerative colitis would also have activated microglia. Treating that person with minocycline should have some stabilizing influence on the microglia, but without resolving the ulcerative colitis, the pro-inflammatory signals continue to be sent around the body.

Turning down the thermostat in my house, when I have a big log fire blazing, has no effect on the temperature. 

The microglia in the brain of people with autism probably should not be activated; we really need to know why they are activated.

If you can work on the numerous processes/pathways leading to “inflammation” you would most likely also achieve some deactivation of the microglia.

Therefore we should look at things like PPAR gamma which are directly relevant to the pathology of autism, and agonists of PPAR gamma also happen to be “anti-inflammatory” and indeed, in the test tube, some can stabilize microglia.

One, far away, day they will bring those ShK-peptides to the market. 

In the meantime, my current targets are Tangeretin and Nobiletin, flavonoids found in tangerines.

For the scientists among you:-

In addition to being a PPAR gamma agonist, Tangeretin is also a known P2Y₂ receptor antagonist.  Both properties are potentially useful.

PPAR gamma has been covered in this blog already.  P2 receptors are a class of Purinergic receptor.  Within the field of purinergic signalling, these receptors have been implicated in learning and memory, locomotor and feeding behavior, and sleep. 

Suramin is used in research as a broad-spectrum antagonist of P2 receptors.

It is Suramin that Robert Naviaux, at UC San Diego, has been researching as a potent autism therapy.  He has shown it effective in mouse models, but the problem is that it is not safe for long term use in humans.  Regular readers should note that, yet again, an anti-parasite drug has been found to have an effect in autism.  Parasites do not cause autism, but understanding them better would be a potential advantage.

Why Suramin, a Century-Old, Anti-Parasitic Drug May Hold the Key to Understanding Autism

Dr. Robert Naviaux's recent finding suggests reversible metabolic syndrome could be at core of autism

The full paper is below:-

Reversal of autism-like behaviors and metabolism in adult mice with single-dose antipurinergic therapy

In particular, P2Y₁₁ is a regulator of immune response.  There are big gaps in the science and I have no idea if tangeretin affects P2Y_11.