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Showing posts with label Pitt Hopkins. Show all posts
Showing posts with label Pitt Hopkins. Show all posts

Thursday, 18 April 2019

Wnt, TCF4 and Pre-myelinating Oligodendrocytes


Cartoons in art class - Monty is getting ready for Easter break, but not in the Maldives

Today’s post may sound very complicated and narrow, but it is very relevant to people with the following: - 

·        Pitt Hopkins Syndrome (insufficient expression of the Transcription Factor #4  TCF4 gene)

·        Multiple Sclerosis

·        Some Mental Retardation/Intellectual Disability (MR/ID)

·        Schizophrenia

·        Impaired Wnt signalling

·        Perhaps PAK1 inhibitor responders

I do feel that Multiple Sclerosis could be treated very much better if some effort was made to translate the existing science, freely available to all, into therapy. You could greatly improve many people’s lives just by repurposing cheap existing drugs.
In simple terms, to produce myelin that you need to coat axons in your brain, you need a type of cell called an oligodendrocyte (OL).  You need a lot of these cells and you need them to get busy. They place tiny pieces of white insulation along axons of your brain cells, this produces the so called “white matter”.  These pieces of insulation are needed to make electrical signals flow correctly in your brain.
It has been shown that in some people the oligodendrocyte precursors (OLPs) do not “mature” and instead get stuck as premyelinated oligodendrocytes (pre-OL). That means reduced myelination and loss of white matter.

It is clearly shown in the graphic below: -








































Tcf4 is expressed in oligodendrocyte lineage in human developmental white matter and in active areas of MS lesions. (A) Tcf4 is expressed in white matter tracts during myelination of human developmental brain at postnatal age 1 mo, 3.5 mo, and 16 mo, but is not expressed by 7 yr. Tcf4 colocalizes with Olig2 when expressed in the developing human corpus callosum. (B) Tcf4 protein expression is evident in active MS lesions, but it is not seen in normal-appearing white matter (NAWM) or in the core of chronic MS lesions. An illustrative MS case is shown with several lesion types present. NAWM stains with Luxol Fast Blue (LFB) and contains sparse LN3(HLA-DR)-positive inflammatory cells, organized SMI-31 axon fibers, and no Tcf4-positive cells. Chronic plaques have sparse LFB staining and LN3-positive cells, intact axons, but no Tcf4-positive cells. In contrast, Tcf4-positive cells are present in active areas of plaques with abundant LN3-positive cells and intact demyelinated axons. Tcf4 expression in active lesions colocalizes (open arrowheads) with a subset of Olig2 cells.


Don’t worry if you don't follow everything. There is nothing wrong with your white matter.
We come back to Wnt signalling that we covered in depth in older posts. This is a complex signalling pathway implicated in autism, some cancers and other conditions. You can both increase and reduce Wnt signalling, which will affect the transcription of numerous genes.
TCF4 is the Pitt Hopkins gene. We have across this syndrome several times, while it is rare, a milder miss-expression of the gene is actually quite common.  Reduced expression of TCF4 is a common feature of MR/ID very broadly. TCF4 has been found to be over-expressed in schizophrenia.
People with Multiple Sclerosis (MS) have been found to have oligodendrocytes “stuck” as non-myelinating (premyelinated oligodendrocytes, pre-OL). Inhibiting the Wnt pathway might play a role in treatment during periods of acute demyelination, when there is a lack of newly minted myelin-producing oligodendrocytes. The study below does refer to Wnt inhibitors in the pipeline as potential cancer therapies.  It looks to me that safe Wnt inhibitors like the cheap drugs widely used to treat children with parasites (Mebendazole/ Niclosamide) could be repurposed to treat the acute phase of multiple sclerosis.
Mebendazole/ Niclosamide are safe and dirt cheap, whereas the (slightly) disease changing MS drugs currently cost $50,000+ a year.

TCF4 links everything together
Wnt signalling needs to be active to block premyelinated oligodendrocytes into transforming into oligodendrocytes (OL). So by inhibiting Wnt signalling you may remove one of the problems in MS; you probably only need to do this during relapses of MS.  
There actually is a finally stage to getting the oligodendrocytes (OL) to myelinate many axons and not be lazy.
In the jargon “dysregulation of Wnt–β-catenin signaling in OLPs results in profound delay of both developmental myelination and remyelination”.
A miss-expression of TCF4 is clearly also going to affect myelination and its does in both Pitt Hopkins and MS.
One feature of Pitt Hopkins (caused by haploinsufficiency of the transcription factor 4) is indeed delayed myelination measured via MRI at the age of 1. By the age of 9 white matter (the myelin-coated part of your brain) appears normal. This fits with what I highlighted in red under figure 6 above.
Nothing is simple. Activating Wnt signalling is known to increase expression of TCF4.  


The progressive loss of CNS myelin in patients with multiple sclerosis (MS) has been proposed to result from the combined effects of damage to oligodendrocytes and failure of remyelination. A common feature of demyelinated lesions is the presence of oligodendrocyte precursors (OLPs) blocked at a premyelinating stage. However, the mechanistic basis for inhibition of myelin repair is incompletely understood. To identify novel regulators of OLP differentiation, potentially dysregulated during repair, we performed a genome-wide screen of 1040 transcription factor-encoding genes expressed in remyelinating rodent lesions. We report that 50 transcription factor-encoding genes show dynamic expression during repair and that expression of the Wnt pathway mediator Tcf4 (aka Tcf7l2) within OLPs is specific to lesioned—but not normal—adult white matter. We report that β-catenin signaling is active during oligodendrocyte development and remyelination in vivo. Moreover, we observed similar regulation of Tcf4 in the developing human CNS and lesions of MS. Data mining revealed elevated levels of Wnt pathway mRNA transcripts and proteins within MS lesions, indicating activation of the pathway in this pathological context. We show that dysregulation of Wnt–β-catenin signaling in OLPs results in profound delay of both developmental myelination and remyelination, based on (1) conditional activation of β-catenin in the oligodendrocyte lineage in vivo and (2) findings from APCMin mice, which lack one functional copy of the endogenous Wnt pathway inhibitor APC. Together, our findings indicate that dysregulated Wnt–β-catenin signaling inhibits myelination/remyelination in the mammalian CNS. Evidence of Wnt pathway activity in human MS lesions suggests that its dysregulation might contribute to inefficient myelin repair in human neurological disorders 
Potential Tcf4-catenin activities in oligodendrocyte development
The pattern of Tcf4 protein expression, from P1 to P30 and during remyelination after injury, defines the window of potential canonical Wnt pathway functions. Within this context, we observed that Tcf4 expression marked 15%–20% of OLPs at any given stage assessed. These findings were consistent with two possibilities. First, Tcf4 expression could demarcate a subset of OLPs. Second, it was possible that Tcf4 expression transiently marks all (or the vast majority) of OLPs during development. Our functional evidence strongly supports the latter conclusion, based on the fact that activity of activated β-catenin is Tcf-dependent (van de Wetering et al. 2002), coupled with the robust phenotype in DA-Cat and APCMin animals, in which we observe pervasive effects of Wnt pathway dysregulation on myelin production throughout the CNS. Interestingly, although Tcf4 proteins are coexpressed with nuclear Olig1 proteins, Tcf4 segregated from cells expressing Olig1 mRNA transcripts, consistent with the possibility that Tcf4 is expressed at a transition stage when nuclear Olig1 proteins become down-regulated during remyelination.

Previous work has suggested inhibitory functions of Tcf4 on myelin basic protein gene expression in vitro (He et al. 2007), and our studies indicate that Tcf4 interactions with β-catenin inhibit myelination in vivo. Additional studies are warranted to rule out possible β-catenin-independent roles for Tcf4 in oligodendrocyte development. Although Wnt pathway activation has conventionally been thought of as activating gene targets, recent work has identified novel Tcf–β-catenin DNA regulatory binding sites that repress targets (Blauwwkamp et al. 2008). In this regard, one intriguing candidate target is HYCCIN (DRCTNNB1A), a Wnt-repressed target (Kawasoe et al. 2000) with essential roles in human myelination (Zara et al. 2006), which is expressed in rodent oligodendrocytes and down-regulated in Olig2cre/DA-Cat mice (Supplemental Fig. 8). Further studies are needed to better understand Tcf4–catenin function and its direct gene targets during oligodendrocyte lineage progression.

Wnt pathway dysregulation in OLPs as a mechanism leading to chronic demyelination in human white matter diseases
Therapeutic opportunities might arise from an enhanced understanding of the process regulating normal kinetics of remyelination. How might the negative regulatory role of the canonical Wnt pathway help to explain the pathology of demyelinating disease? Delayed remyelination due to Wnt pathway dysregulation in OLPs could lead to chronic demyelination by OLPs then missing a “critical window” for differentiation (Miller and Mi 2007; Franklin and Ffrench-Constant 2008). This “dysregulation model” of remyelination failure requires the Wnt pathway to be active during acute demyelination, as suggested by data from our animal systems and human MS tissue.
Canonical WNT signaling has been implicated in a variety of human diseases (Nelson and Nusse 2004), and gain-of-function mutations in β-catenin are etiologic in several cancers including the majority of colon adenocarcinomas. Approaches for treating Wnt-dependent cancers by promoting differentiation (and hence cell cycle arrest or apoptosis) using pharmacological inhibitors of the pathway are under development (Barker and Clevers 2005). It is possible that such antagonists might play a role in the therapeutic enhancement of remyelination by normalizing the kinetics of myelin repair. If so, the animal models described here (e.g., APC+/−) should be useful in preclinical testing. However, it is important to note that while dysregulation of a pathway might delay remyelination, it is overly simplistic to expect that inhibition of the same pathway would accelerate repair in the complex milieu of an MS lesion in which several inhibitory pathways might be active, compounded by the presence of myelin debris (Kotter et al. 2006). Indeed, because of the need to synergize with other processes (e.g., those associated with inflammation), accelerated differentiation might negatively affect repair (Franklin and Ffrench-Constant 2008). Further work is needed to comprehensively understand interactions of regulatory networks required for optimal remyelination and how these may be dysregulated in human demyelinating diseases.

Neurologic and ocular phenotype in Pitt-Hopkins syndrome and a zebrafish model.


Abstract


In this study, we performed an in-depth analysis of the neurologic and ophthalmologic phenotype in a patient with Pitt-Hopkins syndrome (PTHS), a disorder characterized by severe mental and motor retardation, carrying a uniallelic TCF4 deletion, and studied a zebrafish model. The PTHS-patient was characterized by high-resolution magnetic resonance imaging (MRI) with diffusion tensor imaging to analyze the brain structurally, spectral-domain optical coherence tomography to visualize the retinal layers, and electroretinography to evaluate retinal function. A zebrafish model was generated by knockdown of tcf4-function by injection of morpholino antisense oligos into zebrafish embryos and the morphant phenotype was characterized for expression of neural differentiation genes neurog1, ascl1b, pax6a, zic1, atoh1a, atoh2b. Data from PTHS-patient and zebrafish morphants were compared. While a cerebral MRI-scan showed markedly delayed myelination and ventriculomegaly in the 1-year-old PTHS-patient, no structural cerebral anomalies including no white matter tract alterations were detected at 9 years of age. Structural ocular examinations showed highly myopic eyes and an increase in ocular length, while retinal layers were normal. Knockdown of tcf4-function in zebrafish embryos resulted in a developmental delay or defects in terminal differentiation of brain and eyes, small eyes with a relative increase in ocular length and an enlargement of the hindbrain ventricle. In summary, tcf4-knockdown in zebrafish embryos does not seem to affect early neural patterning and regionalization of the forebrain, but may be involved in later aspects of neurogenesis and differentiation. We provide evidence for a role of TCF4/E2-2 in ocular growth control in PTHS-patients and the zebrafish model. 


Conclusion  

If you have a myelinating disease, you might want to read up on TCF4 and Wnt signalling. Probably not what the Minions take to read on the beach in the Maldives.

We also should recall the importance of what I am calling the "what, when and where" in neurological disorders. This is important for late onset disorders like schizophrenia, since the symptoms often develops in late teenage years and so it is potentially preventable, if identified early enough.

Today we see that TCF4 is expressed in white matter only in early childhood. If you knew what changes take place in the brains of children who go on to develop schizophrenia, you might well be able to prevent its onset.

Preventing some autism is already possible, as has been shown in mouse models, but in humans it is more complicated because of the "when" and quite literally the "where". There will be a post showing how the brain overgrowth typical of autism can be prevented using bumetanide, before it occurs, at least in mice.


  












Tuesday, 15 January 2019

More Myelin? Or just Better Myelination - Intelligence, PDE4 and Clemastine again




Myelination in the Central Nervous System (CNS)                  Oligodendrocyte myelinating multiple axons

The previous post on myelin was this one.


In that post we saw that you can activate P2X7 receptors with an antihistamine called Clemastine and you can block P2X7 with another cheap antihistamine called Oxatomide. The P2X7 receptor plays a role in both inflammation and myelination and this receptor appears to be linked to neurological disorders including schizophrenia and even depression.
In that post I also compared experimental MS therapies with experimental autism therapies.




The yellow box means, we know it works, at least for some people, based on trial results.

The widely available PDE4 inhibitor, Roflumilast, has been patented as a cognitive enhancer, but even at that lower dose it can make people vomit.  Ibudilast seems to have fewer side effects and is under investigation in the US to treat MS, but is currently only approved in Japan and as an asthma therapy.
The logical next step is to investigate the two P2X7 modifying antihistamines, which should have opposing effects.
Oxatomide is widely used in Italy. Clemastine is OTC in the US and the UK.
I did some more investigation of Clemastine and came across some encouraging reports of off-label use in psychiatry at modest doses. Off label use to treat MS at high doses was associated with quite negative reports, due to the sedating effect, which is inevitable with antihistamines that can cross the blood brain barrier.
Today’s post goes into more detail about myelination and concludes with the open question of who might actually benefit from a half dose of clemastine, (Dayhist in the US, Tavegil in the UK); clearly some people do already benefit. 
At least one US child psychiatrist is a fan and the research suggests many conditions might benefit, ranging from severe to more trivial.  At 15-20 times higher dosage, clemastine is proposed as a therapy for Multiple Sclerosis (MS), but at that dosage clemastine is highly sedating. High dose clemastine might be a potential immediate response to the onset of regression in autism and CDD (Childhood Disintegrative Disorder).
Clemastine and Ibudilast have different modes of action. Clemastine works by activating P2X7 receptors in oligodendrocytes (in the CNS) and schwann cells (in the PNS) to make more myelin.
PDE4 inhibitors cause enhanced differentiation of OPCs (oligodendrocyte progenitor cells). OPC are precursors to oligodendrocytes.
So Roflumilast and Ibudilast should make more oligodendrocytes, while clemastine just kicks the ones you already have to work harder.  So in any one person the effect of these two types of drug may very well differ. 
Also, note that myelin needs to be constantly repaired in a process naturally called remyelination. So really we are just trying to benefit from improving this already existing repair service.

Some relevant background information:



“Myelination is only prevalent in a few brain regions at birth and continues into adulthood. The entire process is not complete until about 25–30 years of age. Myelination is an important component of intelligence. Neuroscientist Vincent J. Schmithorst proposes that there is a correlation with white matter and intelligence. People with greater white matter had higher IQs. A study done with rats by Janice M. Juraska showed that rats that were raised in an enriched environment had more myelination in their corpus callosum. 
In cerebral palsy, spinal cord injury, stroke and possibly multiple sclerosis, oligodendrocytes are thought to be damaged by excessive release of the neurotransmitter, glutamate. Damage has also been shown to be mediated by N-methyl-D-aspartate receptors. Oligodendrocyte dysfunction may also be implicated in the pathophysiology of schizophrenia and bipolar disorder.”

The role of myelin
Myelin has been compared to the insulation on electrical cables.  If only it was that simple, there would not be so many genes involved in the process.

Nodes of Ranvier do matter
If you look at the above graphic of a neuron you will see gaps in the myelin, that are called Nodes of Ranvier.
The electrical signal does not pass along the axon like a piece of copper wire, rather it jumps from one Node of Ranvier to the next, in a process called saltatory conduction.
Also each subsequent piece of myelin along the length of an axon is connected to a different oligodendrocyte. Otherwise there would be no electrical conduction possible; there has to be a “potential difference” for a current to flow.
Each oligodendrocyte can be connected to 50 different pieces of myelin, many on different axons. Just imagine what that looks like; forget the spaghetti of cables connected to your TV, this is something really jumbled up.
If the electrical signal jumps to an adjacent axon rather than jumping along the same axon, there will be a problem.
If there is too much myelin produced you might squeeze out the node of Ranvier and then the signal cannot pass along to the next neuron.



Myelination Defects in Autism
We have already seen in previous posts that myelination is often found to be abnormal in autism.
A very thorough recent study looked at myelination in a number of single gene autisms. The conclusion was that in these very different types of autism there was a common theme of defective myelination.
This adds further weight to the idea of considering impaired myelination a key feature of much autism.
Loss of myelination has been suggested to be a core feature of regressive autism and I propose a very likely driver of Childhood Disintegrative Disorder (CDD).
“Improving myelination” rather than simply “more myelination” might well be very helpful to many types of severe autism. It seems that even in much milder neurological conditions improving myelination can be therapeutic.
The usual target of experimental myelination therapies is Multiple Sclerosis (MS), it may also be the hardest to treat.
Some researchers and clinicians are repurposing MS therapies for other neurological disorders, either in mouse models or in humans.  This seems like a very good idea to me. 

One Sentence Summary: RNA sequencing of seven syndromic autism mouse models identify myelination genes disrupted in human ASD.

Autism Spectrum Disorder (ASD) is genetically heterogeneous in nature with convergent symptomatology, suggesting dysregulation of common molecular pathways. We analyzed transcriptional changes in the brains of five independent mouse models of Pitt-Hopkins Syndrome (PTHS), a syndromic ASD caused by autosomal dominant mutation in TCF4, and identified considerable overlap in differentially expressed genes (DEGs). Gene and cell-type enrichment analyses of these DEGs identified oligodendrocyte dysregulation that was subsequently validated by decreased protein levels. We further showed significant enrichment of myelination genes was prevalent in two additional mouse models of ASD (Ptenm3m4/m3m4, Mecp2KO). Moreover, we integrated syndromic ASD mouse model DEGs with ASD risk-gene sets (SFARI) and human idiopathic ASD postmortem brain RNA-seq and found significant enrichment of overlapping DEGs and common biological pathways associated with myelination and oligodendrocyte differentiation. These results from seven independent mouse models are validated in human brain, implicating disruptions in myelination is a common ASD pathophysiology.

To address these questions, we performed integrative transcriptomic analyses of seven independent mouse models of three syndromic forms of ASD generated across five laboratories, and assessed dysregulated genes and their pathways in human postmortem brain from patients with ASD and unaffected controls. These cross-species analyses converged on shared disruptions in myelination and axon development across both syndromic and idiopathic ASD, highlighting both the face validity of mouse models for these disorders and identifying novel convergent molecular phenotypes amendable to rescue with therapeutics. 

Shared myelination gene regulation between mouse models of syndromic ASD. Venn diagram of DEGs (differentially expressed genes) in each mouse model of ASD




Top GO (Gene ontology) terms of the CAGs (convergent ASD genes) enrich for myelination processes



P2X purinoceptor 7 is a protein that in humans is encoded by the P2RX7 gene.

The product of this gene belongs to the family of purinoceptors for ATP. Multiple alternatively spliced variants which would encode different isoforms have been identified although some fit nonsense-mediated decay criteria.
The receptor is found in the central and peripheral nervous systems, in microglia, in macrophages, in uterine endometrium, and in the retina. The P2X7 receptor also serves as a pattern recognition receptor for extracellular ATP-mediated apoptotic cell death, regulation of receptor trafficking, mast cell degranulation, and inflammation.


Our findings point to P2X7R as a potential therapeutic target in schizophrenia.


The P2X7 purinergic receptor: An emerging therapeutic target in cardiovascular diseases

The P2X7 purinergic receptor, a calcium permeable cationic channel, is activated by extracellular ATP. Most studies show that P2X7 receptor plays an important role in the nervous system diseases, immune response, osteoporosis and cancer. Mounting evidence indicates that P2X7 receptor is also associated with cardiovascular disease. For example, the P2X7 receptor activated by ATP can attenuate myocardial ischemia-reperfusion injury. By contrast, inhibition of P2X7 receptor decreases arrhythmia after myocardial infarction, prolongs cardiac survival after a long term heart transplant, alleviates the dilated cardiomyopathy and the autoimmune myocarditis process. The P2X7 receptor also mitigates vascular diseases including atherosclerosis, hypertension, thrombosis and diabetic retinopathy. This review focuses on the latest research on the role and therapeutic potential of P2X7 receptor in cardiovascular diseases.

Clemastine is an extracellularly binding allosteric P2X7 receptor modulator.
Clemastine can potentiate the sensitivity of P2X7 to lower ATP concentrations. Additionally, clemastine increases the release of IL-1β from macrophages. Thus, clemastine may be a potential P2X7 activator.

Brain ischemia leading to stroke is a major cause of disability in developed countries. Therapeutic strategies have most commonly focused on protecting neurons from ischemic damage. However, ischemic damage to white matter causes oligodendrocyte death, myelin disruption, and axon dysfunction, and it is partially mediated by glutamate excitotoxicity. We have previously demonstrated that oligodendrocytes express ionotropic purinergic receptors. The objective of this study was to investigate the role of purinergic signaling in white matter ischemia. We show that, in addition to glutamate, enhanced ATP signaling during ischemia is also deleterious to oligodendrocytes and myelin, and impairs white matter function. Thus, ischemic oligodendrocytes in culture display an inward current and cytosolic Ca(2+) overload, which is partially mediated by P2X7 receptors. Indeed, oligodendrocytes release ATP after oxygen and glucose deprivation through the opening of pannexin hemichannels. Consistently, ischemia-induced mitochondrial depolarization as well as oxidative stress culminating in cell death are partially reversed by P2X7 receptor antagonists, by the ATP degrading enzyme apyrase and by blockers of pannexin hemichannels. In turn, ischemic damage in isolated optic nerves, which share the properties of brain white matter, is greatly attenuated by all these drugs. Ultrastructural analysis and electrophysiological recordings demonstrated that P2X7 antagonists prevent ischemic damage to oligodendrocytes and myelin, and improved action potential recovery after ischemia. These data indicate that ATP released during ischemia and the subsequent activation of P2X7 receptor is critical to white matter demise during stroke and point to this receptor type as a therapeutic target to limit tissue damage in cerebrovascular diseases.

Clemastine as a practical intervention
I came across a discussion among MS sufferers and a specific comment from a US child psychiatrist that drew my attention.


Daniel Kerlinsky says:   september 1 1, 2018 at 123 AM

Clemastine is a highly effective medication for re-myelination of white matter fiber bundles that connect neurons everywhere in the brain.
High doses aren't needed. One quarter of a 2.68 mg tablet is enough to start recruiting new oligodendrocytes to start making and applying myelin.
It does not have to be taken every day; it can be taken twice a week and still have a positive effect by recruiting the worker cells that repair the brain.
Remember normal myelination starts at the top of the brain and works downward during childhood development. At first the baby can't hold its head up, then it can sit up, then crawl, then stand.
Many MS lesions are located further down inside the brain and spinal cord so it takes time to get there.
The anti-inflammatory Minocycline taken once or twice a week is needed to stop the inflammatory part of the disease.                                                                            
And it takes cranio-sacral therapy to take full advantage of the new myelin which plumps the brain and even lubricates stiff joints like the sphenoid-occipital junction.
Don't give up on clemastine.

Its first and most obvious effect is improved emotional self regulation. Because myelination increases the speed of information processing ten-fold you will notice that thinking better comes next.
I can't tell you how long it will take to notice a difference. But the MS patient who told me about Clemastine got up out of her electric wheel chair and walked down the hall and back without a walker or her canes for the first time in two years.
It works great for kids with tantrums and developmental problems in about a month. It helps people with chronic depression and PTSD in about three months.
Back your dose down to 1.34 mg or 0.67 mg and give it two years. It takes a toddler that long.„



Increasing evidence suggests that white matter disorders based on myelin sheath impairment may underlie the neuropathological changes in schizophrenia. But it is unknown whether enhancing remyelination is a beneficial approach to schizophrenia. To investigate this hypothesis, we used clemastine, an FDA-approved drug with high potency in promoting oligodendroglial differentiation and myelination, on a cuprizone-induced mouse model of demyelination. The mice exposed to cuprizone (0.2% in chow) for 6 weeks displayed schizophrenia-like behavioral changes, including decreased exploration of the center in the open field test and increased entries into the arms of the Y-maze, as well as evident demyelination in the cortex and corpus callosum. Clemastine treatment was initiated upon cuprizone withdrawal at 10 mg/kg per day for 3 weeks. As expected, myelin repair was greatly enhanced in the demyelinated regions with increased mature oligodendrocytes (APC-positive) and myelin basic protein. More importantly, the clemastine treatment rescued the schizophrenia-like behavioral changes in the open field test and the Y-maze compared to vehicle, suggesting a beneficial effect via promoting myelin repair. Our findings indicate that enhancing remyelination may be a potential therapy for schizophrenia.

Altered myelin structure and oligodendrocyte function have been shown to correlate with cognitive and motor dysfunction and deficits in social behavior. We and others have previously demonstrated that social isolation in mice induced behavioral, transcriptional, and ultrastructural changes in oligodendrocytes of the prefrontal cortex (PFC). However, whether enhancing myelination and oligodendrocyte differentiation could be beneficial in reversing such changes remains unexplored. To test this hypothesis, we orally administered clemastine, an antimuscarinic compound that has been shown to enhance oligodendrocyte differentiation and myelination in vitro, for 2 weeks in adult mice following social isolation. Clemastine successfully reversed social avoidance behavior in mice undergoing prolonged social isolation. Impaired myelination was rescued by oral clemastine treatment, and was associated with enhanced oligodendrocyte progenitor differentiation and epigenetic changes. Clemastine induced higher levels of repressive histone methylation (H3K9me3), a marker for heterochromatin, in oligodendrocytes, but not neurons, of the PFC. This was consistent with the capability of clemastine in elevating H3K9 histone methyltransferases activity in cultured primary mouse oligodendrocytes, an effect that could be antagonized by cotreatment with muscarine. Our data suggest that promoting adult myelination is a potential strategy for reversing depressive-like social behavior.

SIGNIFICANCE STATEMENT Oligodendrocyte development and myelination are highly dynamic processes influenced by experience and neuronal activity. However, whether enhancing myelination and oligodendrocyte differentiation is beneficial to treat depressive-like behavior has been unexplored. Mice undergoing prolonged social isolation display impaired myelination in the prefrontal cortex. Clemastine, a Food and Drug Administration-approved antimuscarinic compound that has been shown to enhance myelination under demyelinating conditions, successfully reversed social avoidance behavior in adult socially isolated mice. This was associated with enhanced myelination and oligodendrocyte differentiation in the prefrontal cortex through epigenetic regulation. Thus, enhancing myelination may be a potential means of reversing depressive-like social behavior.



BACKGROUND:

Multiple sclerosis is a degenerative inflammatory disease of the CNS characterised by immune-mediated destruction of myelin and progressive neuroaxonal loss. Myelin in the CNS is a specialised extension of the oligodendrocyte plasma membrane and clemastine fumarate can stimulate differentiation of oligodendrocyte precursor cells in vitro, in animal models, and in human cells. We aimed to analyse the efficacy and safety of clemastine fumarate as a treatment for patients with multiple sclerosis.

METHODS:


We did this single-centre, 150-day, double-blind, randomised, placebo-controlled, crossover trial (ReBUILD) in patients with relapsing multiple sclerosis with chronic demyelinating optic neuropathy on stable immunomodulatory therapy. Patients who fulfilled international panel criteria for diagnosis with disease duration of less than 15 years were eligible. Patients were randomly assigned (1:1) via block randomisation using a random number generator to receive either clemastine fumarate (5·36 mg orally twice daily) for 90 days followed by placebo for 60 days (group 1), or placebo for 90 days followed by clemastine fumarate (5·36 mg orally twice daily) for 60 days (group 2). The primary outcome was shortening of P100 latency delay on full-field, pattern-reversal, visual-evoked potentials. We analysed by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT02040298.

FINDINGS:


Between Jan 1, 2014, and April 11, 2015, we randomly assigned 50 patients to group 1 (n=25) or group 2 (n=25). All patients completed the study. The primary efficacy endpoint was met with clemastine fumarate treatment, which reduced the latency delay by 1·7 ms/eye (95% CI 0·5-2·9; p=0·0048) when analysing the trial as a crossover. Clemastine fumarate treatment was associated with fatigue, but no serious adverse events were reported.

INTERPRETATION:


To our knowledge, this is the first randomised controlled trial to document efficacy of a remyelinating drug for the treatment of chronic demyelinating injury in multiple sclerosis. Our findings suggest that myelin repair can be achieved even following prolonged damage.



Drug: Clemastine

12mg (4mg 3x/day) clemastine for 7 days followed by 8mg clemastine (4mg 2x/day) until 3 months. Patients will be off treatment from 3-9 months and will be reevaluated at 9 months.



Conclusion
Hopefully this post takes us one step closer to finding safe, side effect free, inexpensive ways to improve myelination in those with impaired myelination.

In the case of treating Multiple Sclerosis (MS), side effects clearly remain an issue. The suggestion of the psychiatrist in today’s post is to just lower the clemastine dosage and give it some time (2 years).  That sounds like smart advice to me.
Fortunately, it appears that in less severe cases of impaired myelination you may not need to wait 2 years.

Who exactly is going to benefit remains an open question, but for people already using H1 antihistamines to treat allergy, or other mast cell activation, switching to a different OTC antihistamine drug does not look like such a big step to take.
People with schizophrenia and allergy also might want to consider switching their antihistamine.

Undoubtedly some people will have the opposite issue with P2X7 receptors and for them there is another old antihistamine drug called Oxatomide.




Wednesday, 19 September 2018

Ketones and Autism Part 5 - BHB, Histone Acetylation Modification, BDNF Expression, PKA, PKB/Akt, Microglial Ramification, Depression and Kabuki Syndrome















Child displaying elongated eyelids typical of Kabuki syndrome
Source: Given by Parents of children pictured with purpose of representing children with kabuki on Wikipedia. 

The syndrome is named after its resemblance to Japanese Kabuki makeup.

As we have discovered in this blog, autism is just a condition where certain genes are over-expressed and other genes are under-expressed. Put like that makes it sound quite simple.

Methylation of histones can either increase or decrease transcription of genes. The subject is highly complex, but we can keep things simple.

The child in the photo above has Kabuki syndrome and is likely to exhibit features of autism.  In most cases this is the result of a lack of expression of the KMT2D/MLL2 gene which encodes a protein called Histone-lysine N-methyltransferase.  Unfortunately, this is quite an important protein, because it promotes the “opening of chromatin”.  It adds a “trimethylation mark to H3K4”, just think of it as a pink post-it on your DNA. 
We get H3K4me3, which is an epigenetic marker (me3, because it is trimethylation). H3K4me3 promotes gene activation and it can cause a relative imbalance between open and closed chromatin states for critical genes. It has been suggested that it may be possible to restore this balance with drugs that promote open chromatin states, such as histone deacetylase inhibitors (HDACi).
What all this means is that people with Kabuki start with under-expression of just one gene, but this leads to the miss-expression of numerous other genes. Because science has figured out what the KMT2D/MLL2 gene does, we can find ways of treating this syndrome.

BHB as an HDAC inhibitor and a treatment for Kabuki syndrome

HDAC inhibitors (HDACi) are also suggested as therapies for other single gene syndromes. We saw in an earlier post that in Pitt Hopkins syndrome people lack Transcription Factor 4 (TCF4). Too little TC4 is not good, but too much TC4 is one feature of schizophrenia.
We saw in the research that we can increase expression of TCF4 using a class 1 HDAC inhibitor and we can also activate the Wnt pathway, which can also be achieved by inhibiting GSK3 (all themes covered in this blog).
So, Pitt Hopkins therapies include: -
·        Wnt activation (covered extensively in this blog) this includes statins and GSK3 inhibitors like Lithium

·        HDAC inhibitors like valproic acid, some cancer drugs, sodium butyrate and indeed the ketone BHB
This also means that people with schizophrenia, and likely too much TCF4, might benefit from the opposite gene expression modification, so a Wnt inhibitor, these include some cheap, safe, drugs used to treat children with parasites (Mebendazole/ Niclosamide etc) and of course GSK3 activators.
It is interesting that after 500 posts of this amateur blog you can start to fit the science together and identify rational therapies for complex disorders and  note that these therapies have much wider application, either to milder conditions or discovering avenues to treat the opposite genetic variation.  The underlying biological themes are all reoccurring in different types of autism/schizophrenia/ bipolar and you do wonder why more has not been done by professionals to apply this knowledge. 500 posts may sound a lot, but for autism researchers this is their paid, full-time job, not just a hobby pastime.

But then again, Simon Baron-Cohen, Head of Cambridge University's Autism Research Centre, recently published an article in which he wrote:

"We at the Autism Research Centre have no desire to cure, prevent or eradicate autism ... As scientists, our agenda is simply to understand the causes of autism." 

Whose team is he playing for?

My conclusion is that perhaps Baron-Cohen has Asperger's himself, because he does not realize that a disorder, severe enough for a medical/psychiatric diagnosis, is a bad thing that should be minimized and ideally prevented, just like any other brain disorder. His cousin the actor Sacha gives a very good impression of someone with bipolar, so perhaps they both need a Wnt activator?

Would a mother with Multiple Sclerosis (MS) want her daughter to also develop MS to share the experience? I think not. If it is just "quirky autism", it does not warrant a medical diagnosis, because it is perfectly okay to be quirky. 

This blog does have many Aspie readers who do want pharmacological therapy and that is their choice; I am fully supportive of them and wish them well.

Back to Kabuki
There is more than one type of HDAC and so there are different types of HDACi.  There are actually 18 HDAC enzymes divided into four classes
The ketone BHB inhibits HDAC class I enzymes called HDAC2 and HDAC3
The good news is that the ketogenic diet, which produces BHB, does indeed show merit as a therapy for Kabuki.

Kabuki syndrome is caused by haploinsufficiency for either of two genes that promote the opening of chromatin. If an imbalance between open and closed chromatin is central to the pathogenesis of Kabuki syndrome, agents that promote chromatin opening might have therapeutic potential. We have characterized a mouse model of Kabuki syndrome with a heterozygous deletion in the gene encoding the lysine-specific methyltransferase 2D (Kmt2d), leading to impairment of methyltransferase function. In vitro reporter alleles demonstrated a reduction in histone 4 acetylation and histone 3 lysine 4 trimethylation (H3K4me3) activity in mouse embryonic fibroblasts from Kmt2d+/βGeo mice. These activities were normalized in response to AR-42, a histone deacetylase inhibitor. In vivo, deficiency of H3K4me3 in the dentate gyrus granule cell layer of Kmt2d+/βGeo mice correlated with reduced neurogenesis and hippocampal memory defects. These abnormalities improved upon postnatal treatment with AR-42. Our work suggests that a reversible deficiency in postnatal neurogenesis underlies intellectual disability in Kabuki syndrome.

Intellectual disability is a common clinical entity with few therapeutic options. Kabuki syndrome is a genetically determined cause of intellectual disability resulting from mutations in either of two components of the histone machinery, both of which play a role in chromatin opening. Previously, in a mouse model, we showed that agents that favor chromatin opening, such as the histone deacetylase inhibitors (HDACis), can rescue aspects of the phenotype. Here we demonstrate rescue of hippocampal memory defects and deficiency of adult neurogenesis in a mouse model of Kabuki syndrome by imposing a ketogenic diet, a strategy that raises the level of the ketone beta-hydroxybutyrate, an endogenous HDACi. This work suggests that dietary manipulation may be a feasible treatment for Kabuki syndrome.
 Although BHB has previously been shown to have HDACi activity (7, 21), the potential for therapeutic application remains speculative. Here, we show that therapeutically relevant levels of BHB are achieved with a KD modeled on protocols that are used and sustainable in humans (22, 23). In addition, we demonstrate a therapeutic rescue of disease markers in a genetic disorder by taking advantage of the BHB elevation that accompanies the KD.
Our findings that exogenous BHB treatment lead to similar effects on neurogenesis as the KD support the hypothesis that BHB contributes significantly to the therapeutic effect. In our previous study (6), the HDACi AR-42 led to improved performance in the probe trial of the MWM for both Kmt2d+/βGeo and Kmt2d+/+ mice (genotype-independent improvement). In contrast, KD treatment only led to improvement in Kmt2d+/βGeo mice (genotype-dependent improvement). This discrepancy may relate to the fact that AR-42 acts as an HDACi but also affects the expression of histone demethylases (24), resulting in increased potency but less specificity. Alternatively, because the levels of BHB appear to be higher in Kmt2d+/βGeo mice on the KD, the physiological levels of BHB might be unable to reach levels in Kmt2d+/+ mice high enough to make drastic changes on chromatin.
In addition to the effects seen on hippocampal function and morphology, we also uncovered a metabolic phenotype in Kmt2d+/βGeo mice, which leads to both increased BHB/AcAc and lactate/pyruvate ratios during ketosis; an increased NADH/NAD+ ratio could explain both observations. This increased NADH/NAD+ ratio may relate to a previously described propensity of Kmt2d+/βGeo mice toward biochemical processes predicted to produce NADH, including beta-oxidation, and a resistance to high-fat-diet–induced obesity (27). If this exaggerated BHB elevation holds true in patients with KS, the KD may be a particularly effective treatment strategy for this patient population; however, this remains to be demonstrated. Alterations of the NADH/NAD+ ratio could also affect chromatin structure through the action of sirtuins, a class of HDACs that are known to be NAD+ dependent (28). Advocates of individualized medicine have predicted therapeutic benefit of targeted dietary interventions, although currently there are few robust examples (2931). This work serves as a proof-of-principle that dietary manipulation may be a feasible strategy for KS and suggests a possible mechanism of action of the previously observed therapeutic benefits of the KD for intractable seizure disorder (22, 23).                   
Kabuki syndrome (KS) (Kabuki make-up syndrome, Niikawa-Kuroki syndrome) is a rare genetic disorder first diagnosed in 1981. Kabuki make-up syndrome (KMS) is a multiple malformation/intellectual disability syndrome that was first described in Japan but is now reported in many other ethnic groups. KMS is characterized by multiple congenital abnormalities: craniofacial, skeletal, and dermatoglyphic abnormalities; intellectual disability; and short stature. Other findings may include: congenital heart defects, genitourinary anomalies, cleft lip and/or palate, gastrointestinal anomalies including anal atresia, ptosis and strabismus, and widely spaced teeth and hypodontia. The KS is associated with mutations in the MLL2 gene in some cases were also observed deletions of KDM6A. This study describes three children with autism spectrum disorders (ASDs) and KS and rehabilitative intervention that must be implemented.

So what?
Unless you know someone with Kabuki syndrome, you might be wondering what does this matter to autism.
What is shows is that BHB/KD is sufficiently potent to be a viable HDAC inhibitor. 
We know that some cancer drug HDAC inhibitors are effective in some mouse models of autism. But these drugs usually have side effects. 

HDAC Inhibitors for which Cancer/Autism? 

BHB is safe endogenous substance, so it is a “natural” HDACi. 

The effect of HDAC2 and HDAC3 on BDNF 
Brain derived neurotropic factor (BDNF) is like brain fertilizer. In some types of autism, you would like more BDNF.
When you exercise you produce BHB and that goes on to trigger the release of BDNF. This process also involves NF-kB activation

Exercise induces beneficial responses in the brain, which is accompanied by an increase in BDNF, a trophic factor associated with cognitive improvement and the alleviation of depression and anxiety. However, the exact mechanisms whereby physical exercise produces an induction in brain Bdnf gene expression are not well understood. While pharmacological doses of HDAC inhibitors exert positive effects on Bdnf gene transcription, the inhibitors represent small molecules that do not occur in vivo. Here, we report that an endogenous molecule released after exercise is capable of inducing key promoters of the Mus musculus Bdnf gene. The metabolite β-hydroxybutyrate, which increases after prolonged exercise, induces the activities of Bdnf promoters, particularly promoter I, which is activity-dependent. We have discovered that the action of β-hydroxybutyrate is specifically upon HDAC2 and HDAC3, which act upon selective Bdnf promoters. Moreover, the effects upon hippocampal Bdnf expression were observed after direct ventricular application of β-hydroxybutyrate. Electrophysiological measurements indicate that β-hydroxybutyrate causes an increase in neurotransmitter release, which is dependent upon the TrkB receptor. These results reveal an endogenous mechanism to explain how physical exercise leads to the induction of BDNF.

Results: ROS was significantly increased in neurons after 6 hours of ketone incubation. However, after 24 hours, neurons show improved efficiency in ATP productions, upregulated expressions of antioxidant enzyme SOD2, and enhanced resistance to excitotoxicity. These effects were significantly abolished in neurons after treatment with TrkB inhibitor. More interestingly, ROS scavengers or blocking ROS-dependent NF-kB activation significantly decreased ketone-dependent BDNF-upregulation in neurons, suggesting that ROS may have increased BDNF expressions to improve mitochondrial respiration as adaptive responses.
Conclusions: 3OHB initially generates ROS and poses oxidative stress. However, ROS appears to trigger adaptive responses against oxidative stress by upregulating BDNF through NF-kB activation, which can improve mitochondrial oxidative capacity and ultimately enhance neuroprotection
BHB/KD promotes PKA/CREB activation 
Another clever way to change the function/expression of multiple genes in one single step is to use a protein kinase.  Up to 30% of all human proteins may be modified by kinase activity.  
A protein kinase is an enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). Phosphorylation usually results in a functional change of the target protein.
In the autism research you may well have come across PKA, PKB (Akt) and PKC. They clearly are disturbed in much autism.
The research shows that BHB activates PKA.
If you want good myelination you need PKA.
This might be another reason why BHB/KD is helpful in people with Multiple Sclerosis.
In much autism the myelin coating is found to be abnormally thin. 

BHB, Microglial Ramification and Depression (yes, depression)
I am increasingly impressed by research from China. The paper below by Chao Huang et al is excellent and I think we need a Chinese on the Dean’s List of this blog, it looks like he is the first.
Nantong, China on the Yangtze River and home to Chao Huang and more than 7 million other people 
Source: Wikipedia Dolly 442

The ketone body metabolite β-hydroxybutyrate induces an antidepression-associated ramification of microglia via HDACs inhibition-triggered Akt-small RhoGTPase activation. 


Abstract


Direct induction of macrophage ramification has been shown to promote an alternative (M2) polarization, suggesting that the ramified morphology may determine the function of immune cells. The ketone body metabolite β-hydroxybutyrate (BHB) elevated in conditions including fasting and low-carbohydrate ketogenic diet (KD) can reduce neuroinflammation. However, how exactly BHB impacts microglia remains unclear. We report that BHB as well as its producing stimuli fasting and KD induced obvious ramifications of murine microglia in basal and inflammatory conditions in a reversible manner, and these ramifications were accompanied with microglial profile toward M2 polarization and phagocytosis. The protein kinase B (Akt)-small RhoGTPase axis was found to mediate the effect of BHB on microglial shape change, as (i) BHB activated the microglial small RhoGTPase (Rac1, Cdc42) and Akt; (ii) Akt and Rac1-Cdc42 inhibition abolished the pro-ramification effect of BHB; (iii) Akt inhibition prevented the activation of Rac1-Cdc42 induced by BHB treatment. Incubation of microglia with other classical histone deacetylases (HDACs) inhibitors, but not G protein-coupled receptor 109a (GPR109a) activators, also induced microglial ramification and Akt activation, suggesting that the BHB-induced ramification of microglia may be triggered by HDACs inhibition. Functionally, Akt inhibition was found to abrogate the effects of BHB on microglial polarization and phagocytosis. In neuroinflammatory models induced by lipopolysaccharide (LPS) or chronic unpredictable stress (CUS), BHB prevented the microglial process retraction and depressive-like behaviors, and these effects were abolished by Akt inhibition. Our findings for the first time showed that BHB exerts anti-inflammatory actions via promotion of microglial ramification. 



NOTE:  Ramified Microglia = Resting Microglia


The brain microglia play important roles in sensing even subtle variations of their milieu. Upon moderate activation, they control brain activity via phagocytosis of cell debris and production of pro-inflammatory mediators and reactive oxygen species. However, a persistent activation would make the microglia transfer into a status with an amoeboid morphology tightly associated with neuronal damage and pro-inflammatory cytokine overproduction.

Unlike the activated microglia, the un-stimulated microglia are in a ramified status with extensively branched processes, an contribute to brain homeostasis via regulation of synaptic remodeling and neurotransmission. The ramified microglia has been shown to be associated with the induction of M2 polarization. A study by McWhorter et al. showed that elongation of macrophage by control of cell shape directly increases the expression of M2 markers and reduces the secretion of proinflammatory cytokines, suggesting that induction of microglial ramification may be a mechanism for regulation of microglial function. Methods that trigger microglial ramification may help treat brain disorders associated with neuroinflammation.
In this study, we found that BHB induces a functional ramification of murine microglia in both basal and inflammatory conditions in vitro and in vivo. The pro-ramification effects of BHB are associated with the change in microglial polarization and phagocytosis as well as the antidepressant-like effects of BHB in LPS- or chronic unpredictable stress (CUS)-stimulated mice. The ramified morphology in microglia is also induced by two BHB-producing stimuli fasting and KD, as well as two other HDACs inhibitors valproic acid (VPA) and trichostatin A (TSA). Given that microglial overactivation can mediate the pathogenesis of depression, induction of microglial ramification by BHB may have therapeutic significance in depression. 

These data confirm that BHB has an ability to transform the activated microglia back to their ramified and resting status in inflammatory conditions.

Recall the recent post about BHB and the Niacin Receptor HCA2/GPR109A in Autism:

The Chinese paper continues:

It is HDACs inhibition but not GPR109A activation that mediates the pro-ramification effect of BHB in microglia Akt inhibition abrogates the effects of BHB on microglial ramification, polarization, and phagocytosis
Akt inhibition prevents the antidepressant-like effects of BHB in acute and chronic depression models

Note that Akt is another name for Protein Kinase B (PKB)

One of the major findings in the present study is that the ketone body metabolite BHB as well as its producing stimuli fasting and KD induced reversible ramifications of murine microglia in vitro and in vivo, and these ramifications were not altered by pro-inflammatory stimuli. The ramified morphology induced by BHB seems to be a signal upstream of microglial polarization, and may mediate the antidepressant-like effect of BHB in depression induced by neuroinflammatory stimuli. Since the regulating effect of BHB in disorders associated with neuroinflammation has been well-documented, our findings provide a novel mechanism for the explanation of the neuroprotective effect of BHB in neurodegenerative and neuropsychiatric disorders from the aspect of the feedback regulation of microglial function by microglial ramification.
Induction of microglial ramification, a strategy neglected by most scientists for a long time, may have more important therapeutic significance than that of regulation of microglial polarization alone at the molecular level.

In experiments in vivo, we showed that BHB ameliorated the depressive-like behaviors induced by two neuroinflammatory stimuli LPS and CUS. These results are in accordance with previous reports, which showed that the BHB-producing stimuli, caloric restriction and fasting, produce potential antidepressant-like activities in both animals and humans. Thus, together with the pro-ramification effect of BHB in microglia in vitro, we speculate that the microglial shape change may be an independent signal that determines microglial function.

Our further analysis showed that the BHB-induced microglial ramification was mediated by the Rac1-Cdc42 signal, as BHB markedly increased the activity of Rac1 and Cdc42, and Rac1/Cdc42 inhibition attenuated the pro-ramification effect of BHB. The PI3K-Akt signal has been shown to mediate the activation of Rac1/Cdc42, and once accepting the signal from Akt, the Rac1-Cdc42 will be mobilized to promote lamellipodia/filopodia formation and cell shape change (Huang et al., 2016a). We showed that the BHB-induced microglial ramification was mediated by the Akt signal, as Akt inhibition suppressed the induction of microglial ramification by BHB. As a functional evidence for the involvement of Akt in the pro-ramification effect of BHB, Akt inhibition was found to block the functional changes in BHB-treated microglia in vitro and in vivo, including blockage of the anti-inflammatory and prophagocytic activity of BHB and abrogation of the antidepressant-like effects of BHB. Since the ramified morphology determines the anti-inflammatory phenotype in macrophages (McWhorter et al., 2013), our data suggest that there may exist a causal relationship between the ramified morphology and microglial function after BHB treatment, and this relationship may evidence the clinical significance of our findings, as the microglial process retraction has been shown to mediate the development of neurodegenerative and neuropsychiatric disorders.

Furthermore, considering the serum level of BHB in humans begin to rise to 6 to 8 mM with prolonged fasting (Cahill, 2006), investigation of whether the pro-ramification effect of BHB exists in human individuals should be of great value for the application of BHB in disease therapy. 


 Exposure to hypobaric hypoxia causes neuron cell damage, resulting in impaired cognitive function. Effective interventions to antagonize hypobaric hypoxia-induced memory impairment are in urgent need. Ketogenic diet (KD) has been successfully used to treat drug-resistant epilepsy and improves cognitive behaviors in epilepsy patients and other pathophysiological animal models. In the present study, we aimed to explore the potential beneficial effects of a KD on memory impairment caused by hypobaric hypoxia and the underlying possible mechanisms. We showed that the KD recipe used was ketogenic and increased plasma levels of ketone bodies, especially β-hydroxybutyrate. The results of the behavior tests showed that the KD did not affect general locomotor activity but obviously promoted spatial learning. Moreover, the KD significantly improved the spatial memory impairment caused by hypobaric hypoxia (simulated altitude of 6000 m, 24 h). In addition, the improving-effect of KD was mimicked by intraperitoneal injection of BHB. The western blot and immunohistochemistry results showed that KD treatment not only increased the acetylated levels of histone H3 and histone H4 compared to that of the control group but also antagonized the decrease in the acetylated histone H3 and H4 when exposed to hypobaric hypoxia. Furthermore, KD-hypoxia treatment also promoted PKA/CREB activation and BDNF protein expression compared to the effects of hypoxia alone. These results demonstrated that KD is a promising strategy to improve spatial memory impairment caused by hypobaric hypoxia, in which increased modification of histone acetylation plays an important role

Exogenous BHB prevents spatial memory impairment induced by hypobaric hypoxia

To further verify whether ketone body, a product of KD, has direct improving effect, we chose the most stable physiologic ketone body, BHB, for the subsequent experiment. In order to mimic the effect of KD as above described, the rats were pre-treated with BHB (at a dose of 200mg/kg/day) for 2 weeks and then submitted to Morris water maze test. Since intraperitoneal injection would allow substances to be absorbed at a slower rate and intraperitoneal injection would produce marginal effect during behavioral tests [16], we used the intraperitoneal injection of BHB, which has been applied in published reports [17, 18]. Although the rats in the control and BHB groups learned to find the platform with the same pattern during 5 days of acquisition training (Fig 4B), BHB could significantly improve the memory impairment induced by hypobaric hypoxia, represented by more crossing number, more time in the target quadrant, and decreased latency to first entry to platform compared to hypobaric hypoxia treatment alone (Fig 4C–4F). These results demonstrated that BHB has a direct memory-improving effect and served as the main executor of KD beneficial effects.

KD increases histone acetylation modification in the hippocampus

A previous study found that BHB is an endogenous HDAC inhibitor, and the KD recipe in our study substantially increased plasma levels of BHB. Then, we detected the effect of KD on histone acetylation in the hippocampus, which is responsible for learning and memory. As shown in Fig 5, the acetylated histone H3 (K9/K14), acetylated histone H3 (K14), and acetylated histone H4 (K12), were all increased in the hippocampus of the KD rats. Although the histone acetylation modifications listed above are decreased in hypoxia-treated rats, KD treatment could reverse the decreased levels of histone acetylation. The same pattern was displayed in the immunohistochemical staining, in which the hypoxia-induced decrease in acetylated histone H3 and acetylated histone H4 in the CA1 region of the hippocampus was reversed by KD treatment  

KD activates PKA/CREB signaling in the hippocampus

To explore a possible underlying mechanism of the beneficial effect of KD treatment on cognition, the activity of the PKA/CREB pathway in the four groups was also evaluated by western blot (Fig 7A). KD treatment was shown to not only increase the levels of PKA substrates and p-CREB (KD vs STD) but also reverse the decline in PKA substrates, p-CREB and CREB (KD-Hy vs STD-Hy). Although KD pre-treatment produced a partial restoration of PKA activity, p-CREB is nearly completely restore to its basic levels, which is may be account for its other upstream kinases, like calmodulin-dependent kinases [19]. Interestingly, the hypoxia-induced down-regulation of BDNF, a well-known neurotrophic factor involved in learning and memory formation processes, was also up-reregulated by KD treatment. These results demonstrated that KD treatment promoted PKA/CREB activation and BDNF protein expression. In order to detect whether KD promoted BDNF expression at mRNA levels, qRT-PCR assays were performed using BDNF specific primers. We found that KD-pretreatment significantly increased mRNA levels compared with that in hypobaric hypoxia group (Fig 7B). Next, we used ChIP-PCR to test if there might be increased enrichment of acetylated histones on the promoter of BDNF gene. We focused on the promoter I of BDNF gene, which response to neuronal activity [20). ]. The results showed that there is increased binding of acetylated histone H3 to the promoter I of BDNF gene (Fig 7C   

Concentrations of acetyl–coenzyme A and nicotinamide adenine dinucleotide (NAD+) affect histone acetylation and thereby couple cellular metabolic status and transcriptional regulation. We report that the ketone body d-β-hydroxybutyrate (βOHB) is an endogenous and specific inhibitor of class I histone deacetylases (HDACs). Administration of exogenous βOHB, or fasting or calorie restriction, two conditions associated with increased βOHB abundance, all increased global histone acetylation in mouse tissues. Inhibition of HDAC by βOHB was correlated with global changes in transcription, including that of the genes encoding oxidative stress resistance factors FOXO3A and MT2. Treatment of cells with βOHB increased histone acetylation at the Foxo3a and Mt2 promoters, and both genes were activated by selective depletion of HDAC1 and HDAC2. Consistent with increased FOXO3A and MT2 activity, treatment of mice with βOHB conferred substantial protection against oxidative stress. 
Abnormalities in mitochondrial function and epigenetic regulation are thought to be instrumental in Huntington's disease (HD), a fatal genetic disorder caused by an expanded polyglutamine track in the protein huntingtin. Given the lack of effective therapies for HD, we sought to assess the neuroprotective properties of the mitochondrial energizing ketone body, D-β-hydroxybutyrate (DβHB), in the 3-nitropropionic acid (3-NP) toxic and the R6/2 genetic model of HD. In mice treated with 3-NP, a complex II inhibitor, infusion of DβHB attenuates motor deficits, striatal lesions, and microgliosis in this model of toxin induced-striatal neurodegeneration. In transgenic R6/2 mice, infusion of DβHB extends life span, attenuates motor deficits, and prevents striatal histone deacetylation. In PC12 cells with inducible expression of mutant huntingtin protein, we further demonstrate that DβHB prevents histone deacetylation via a mechanism independent of its mitochondrial effects and independent of histone deacetylase inhibition. These pre-clinical findings suggest that by simultaneously targeting the mitochondrial and the epigenetic abnormalities associated with mutant huntingtin, DβHB may be a valuable therapeutic agent for HD.  

Conclusion
At the end of this fifth post on ketones and autism, I think we have established beyond any doubt that ketones can do some amazing things for numerous dysfunctions and diseases.
The question remains how much you need to achieve the various possible benefits. 
The next question, already put to me by one parent, is how do you measure such a benefit.  Some people’s idea of treating autism is just to eradicate disturbing behaviours like SIB and ensure a placid, cooperative child when out in public.  Other people notice small cognitive and speech changes, because they spend hours a day teaching their child. Small but significant cognitive improvement may not show up on autism rating scales.
You would expect a dose dependent response, so the more ketones the bigger the response, which suggests that the full Ketogenic Diet (KD) is the ultimate option.
A lot does seem to be possible just with BHB and C8 (caprylic acid) as supplements to a regular diet.
Adults with Alzheimer’s, or Huntington’s, or Multiple Sclerosis (MS) all stand to potentially benefit from ketone supplements.
Children/adults with certain single-gene autisms, not limited to Kabuki and Pitt Hopkins potentially should benefit from ketone supplements.
Interestingly, another benefit of BHB is on mood; it seems to make some people just feel much better, apparently all due to the effect on microglia. So perhaps autism parents who take antidepressants should try BHB instead.