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.  

Dysregulation of the Wnt pathway inhibits timely myelination and remyelination in the mammalian CNS

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 APC^Min 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 APC^Min 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.


  

Pterostilbene for Neuromodulation – worth a look?

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Blueberries

A common criticism of this blog is that it is mainly about prescription drugs rather than OTC supplements.

Today’s post is about a supplement that is highly regarded by our reader Ling.

Pterostilbene is like a super potent version of resveratrol.  

Resveratrol is quite well known and has long been put forward as having some potentially highly beneficial health effects, but in practise it is just too poorly absorbed to have much effect in humans.

Pterostilbene is found in blueberries.  Also found in blueberries is Anthocyanin, which is worth a mention in this post, it is what gives blueberries their colour; very often it is the colour in a food that underlies part of its health benefit. This is why eating a mixed colour diet is a wise idea.

Aronia is extremely rich in anthocyanins and Aronia juice is very common where I live. We even have a bottle of the dark coloured juice in the kitchen.

The purple colour in beetroot is betanin, a so-called betacyanin and may well have anti-Alzheimer’s effects, inhibiting plaque formation.

Anthocyanin is put forward as one reason certain Japanese who eat large amounts of purple sweet potato do not suffer much cancer or dementia and live a very long time.

The Okinawan Diet and Anthocyanin

Today we are mainly looking at pterostilbene, but if you want Anthocyanins, to avoid dementia, just eat blue and purple coloured fruit and vegetables on a very regular basis.

Ling has proposed pterostilbene as a PDE4 inhibitor, but as is often the case, it has numerous other effects, so it would be hard to know which is the main reason it might be therapeutic.  

Known biological effects of Pterostilbene                                                                                   

Here is an excellent graphic that highlights many of the effects of Pterostilbene, other than on PDE4.

The regular readers of this blog will note that the great majority of the above signalling molecules are implicated in autism.

The proposed effects on the brain are highlighted in the next graphic

The source paper is here: -  

Effects of pterostilbene and resveratrol on brain and behavior

           

Based on the evidence presented, PTE (Pterostilbene) is more bioavailable and better at evoking molecular and functional events than RES (Resveratrol) in vivo. 

Although clinical trials are underway to assess the effects of RES in diseases such as dementia and AD, pre-clinical and clinical studies on PTE have yet to be conducted. Furthermore, the biological effects of many of the structural analogues of RES and PTE are unknown, and no studies have identified the metabolites of RES or PTE in brain tissues. There is a need for future studies to identify means of enhancing the efficacy and bioavailability of these compounds and to analyse the metabolites of these compounds in thebrain. Altogether, the evidence from a variety of studies strongly suggests the potential of RES and PTE as promising bioactive agents to improve brain health and prevent neurodegeneration. 

Most research, but not all, concerns aging and dementia. 

A Review of Pterostilbene Antioxidant Activity and Disease Modification

Pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene) is a natural dietary compound and the primary antioxidant component of blueberries. It has increased bioavailability in comparison to other stilbene compounds, which may enhance its dietary benefit and possibly contribute to a valuable clinical effect. Multiple studies have demonstrated the antioxidant activity of pterostilbene in both in vitro and in vivo models illustrating both preventative and therapeutic benefits. The antioxidant activity of pterostilbene has been implicated in anticarcinogenesis, modulation of neurological disease, anti-inflammation, attenuation of vascular disease, and amelioration of diabetes. In this review, we explore the antioxidant properties of pterostilbene and its relationship to common disease pathways and give a summary of the clinical potential of pterostilbene in the prevention and treatment of various medical conditions.

Resveratrol, pterostilbene, and dementia

Resveratrol is a natural phytoestrogen with neuroprotective properties. Polyphenolic compounds including resveratrol exert in vitro antioxidant, anti-inflammatory, and antiamyloid effects. Resveratrol and its derivative pterostilbene are able to cross the blood-brain barrier and to influence brain activity. The present short review summarizes the available evidence regarding the effects of these polyphenols on pathology and cognition in animal models and human subjects with dementia. Numerous investigations in cellular and mammalian models have associated resveratrol and pterostilbene with protection against dementia syndromes such as Alzheimer's disease (AD) and vascular dementia. The neuroprotective activity of resveratrol and pterostilbene demonstrated in in vitro and in vivo studies suggests a promising role for these compounds in the prevention and treatment of dementia. In comparison to resveratrol, pterostilbene appears to be more effective in combatting brain changes associated with aging. This may be attributed to the more lipophilic nature of pterostilbene with its two methoxyl groups compared with the two hydroxyl groups of resveratrol. The findings of available intervention trials of resveratrol in individuals with mild cognitive impairment or AD do not provide evidence of neuroprotective or therapeutic effects. Future clinical trials should be conducted with long-term exposure to preparations of resveratrol and pterostilbene with high bioavailability.

Low-dose pterostilbene, but not resveratrol, is apotent neuromodulator in aging and Alzheimer's disease.

Recent studies have implicated resveratrol and pterostilbene, a resveratrol derivative, in the protection against age-related diseases including Alzheimer's disease (AD). However, the mechanism for the favorable effects of resveratrol in the brain remains unclear and information about direct cross-comparisons between these analogs is rare. As such, the purpose of this study was to compare the effectiveness of diet-achievable supplementation of resveratrol to that of pterostilbene at improving functional deficits and AD pathology in the SAMP8 mouse, a model of accelerated aging that is increasingly being validated as a model of sporadic and age-related AD. Furthermore we sought to determine the mechanism of action responsible for functional improvements observed by studying cellular stress, inflammation, and pathology markers known to be altered in AD. Two months of pterostilbene diet but not resveratrol significantly improved radial arm water maze function in SAMP8 compared with control-fed animals. Neither resveratrol nor pterostilbene increased sirtuin 1 (SIRT1) expression or downstream markers of sirtuin 1 activation. Importantly, markers of cellular stress, inflammation, and AD pathology were positively modulated by pterostilbene but not resveratrol and were associated with upregulation of peroxisome proliferator-activated receptor (PPAR) alpha expression. Taken together our findings indicate that at equivalent and diet-achievable doses pterostilbene is a more potent modulator of cognition and cellular stress than resveratrol, likely driven by increased peroxisome proliferator-activated receptor alpha expression and increased lipophilicity due to substitution of hydroxy with methoxy group in pterostilbene                                                                                                        

Effect of resveratrol and pterostilbene on aging and longevity.

Over the past years, several studies have found that foods rich in polyphenols protect against age-related disease, such as atherosclerosis, cardiovascular disease, cancer, arthritis, cataracts, osteoporosis, type 2 diabetes (T2D), hypertension and Alzheimer's disease. Resveratrol and pterostilbene, the polyphenol found in grape and blueberries, have beneficial effects as anti-aging compounds through modulating the hallmarks of aging, including oxidative damage, inflammation, telomere attrition and cell senescence. In this review, we discuss the relationship between resveratrol and pterostilbene and possible aging biomarker, including oxidative stress, inflammation, and high-calorie diets. Moreover, we also discuss the positive effect of resveratrol and pterostilbene on lifespan, aged-related disease, and health maintenance. Furthermore, we summarize a variety of important mechanisms modulated by resveratrol and pterostilbene possibly involved in attenuating age-associated disorders. Overall, we describe resveratrol and pterostilbene potential for prevention or treatment of several age-related diseases by modulating age-related mechanisms.

One area of autism research concerns targeting mTOR signalling. This is covered in the paper below

Reversing autism by targeting downstream mTOR signalling

and was the subject of this blog post from 2015

https://epiphanyasd.blogspot.com/2015/06/mtor-indirect-inhibition-holy-grail-for.html

Targeting the PI3K/Akt/mTOR signaling pathway by pterostilbene attenuates mantle cell lymphoma progression.

Mantle cell lymphoma (MCL) is an aggressive and mostly incurable B-cell malignancy with frequent relapses after an initial response to standard chemotherapy. Therefore, novel therapies are urgently required to improve MCL clinical outcomes. In this study, MCL cell lines were treated with pterostilbene (PTE), a non-toxic natural phenolic compound primarily found in blueberries. The antitumor activity of PTE was examined by using the Cell Counting Kit-8, apoptosis assays, cell cycle analysis, JC-1 mitochondrial membrane potential assay, western blot analysis, and tumor xenograft models. PTE treatment induced a dose-dependent inhibition of cell proliferation, including the induction of cell apoptosis and cell cycle arrest at the G0/G1 phase. Moreover, the PI3K/Akt/mTOR pathway was downregulated after PTE treatment, which might account for the anti-MCL effects of PTE. Synergistic cytotoxicity was also observed, both in MCL cells and in xenograft mouse models, when PTE was administered in combination with bortezomib (BTZ). The antitumor effects of PTE shown in our study provide an innovative option for MCL patients with poor responses to standardized therapy. It is noteworthy that the treatment combining PTE with BTZ warrants clinical investigation, which may offer an alternative and effective MCL treatment in the future.

And finally, PDE4

Inhibiting PDE4 has some very useful anti-inflammatory benefits. It may also improve myelination and indeed cognition.  PDE4 inhibitors are currently used to treat severe asthma and in clinical trials for Multiple Sclerosis (MS) and cognitive enhancement.

There are different sub-types of PDE4.

Inhibiting one of the subtypes has the tendency to make you want to vomit.  This is currently the drawback that limits the use of PDE4 inhibiting drugs.

A selective PDE4 inhibitor is required.

As Ling has found, research does indeed show that pterostilbene is a PDE4 inhibitor.

The molecular basis for the inhibition of phosphodiesterase-4D by three natural resveratrol analogs. Isolation, molecular docking, molecular dynamics simulations, binding free energy, and bioassay.

The phosphodiesterase-4 (PDE4) enzyme is a promising therapeutic target for several diseases. Our previous studies found resveratrol and moracin M to be natural PDE4 inhibitors. In the present study, three natural resveratrol analogs [pterostilbene, (E)-2',3,5',5-tetrahydroxystilbene (THSB), and oxyresveratrol] are structurally related to resveratrol and moracin M, but their inhibition and mechanism against PDE4 are still unclear. A combined method consisting of molecular docking, molecular dynamics (MD) simulations, binding free energy, and bioassay was performed to better understand their inhibitory mechanism. The binding pattern of pterostilbene demonstrates that it involves hydrophobic/aromatic interactions with Phe340 and Phe372, and forms hydrogen bond(s) with His160 and Gln369 in the active site pocket. The present work also reveals that oxyresveratrol and THSB can bind to PDE4D and exhibits less negative predicted binding free energies than pterostilbene, which was qualitatively validated by bioassay (IC50=96.6, 36.1, and 27.0μM, respectively). Additionally, a linear correlation (R(2)=0.953) is achieved for five PDE4D/ligand complexes between the predicted binding free energies and the experimental counterparts approximately estimated from their IC50 values (≈RT ln IC50). Our results imply that hydrophobic/aromatic forces are the primary factors in explaining the mechanism of inhibition by the three products. Results of the study help to understand the inhibitory mechanism of the three natural products, and thus help the discovery of novel PDE4 inhibitors from resveratrol, moracin M, and other natural products.

Conclusion

Based on Ling’s recommendation, I have ordered some Pterostilbene and I am curious to see its effects. It is another substance that might be helpful for older adults, if not for your case of autism.

It is clear that in most cases resveratrol is a substance whose effect is limited to the test tube rather than humans. As a “super-resveratrol” we should take a closer look at Pterostilbene.

Eating large amounts of fruits, vegetables and berries with anthocyanins and betacyanins is going to do you no harm and does look a way to possibly secure a long healthy future, like those Japanese centenarians in Okinawa.

Choose your Statin with Care in FXS, NF1 and idiopathic Autism

There are several old posts in this blog about the potential to treat some autism using statins; this has nothing to do with their ability to lower cholesterol. 

Statins are broadly anti-inflammatory but certain statins do some other particularly clever things. This led me to use Atorvastatin and Fragile-X researchers to use Lovastatin.

Fragile X is suggested by an elongated face and big/protruding ears; 

other features include MR/ID and autism.

I was recently forwarded a Scottish study showing why Simvastatin does not work in Fragile X syndrome, but Lovastatin does.

Fragile X mental retardation protein (FMR1) acts to regulate translation of specific mRNAs through its binding of eIF4E (see chart below). In people with Fragile X, they lack the FMR1 protein. Boys are worse affected than girls, because females have a second X chromosome and so a "spare" copy of the gene.

         Simvastatin does not reduce ERK1/2 or mTORC1 activation in the Fmr1-/y hippocampus.

So  ? = Does NOT inhibit

The researchers in Scotland did not test Atorvastatin in their Fragile X study.

The key is to reduce Ras. In the above graphic it questions does Simvastatin inhibit RAS and Rheb.

RASopathies have been covered in this blog. Too much of the Ras protein is a common feature of much ID/MR. Investigating RAS took me to PAK1 inhibitors and the experimental drug FRAX486. This drug was actually developed to treat Fragile X; it is now owned by Roche. At least one person is using FRAX486 to treat autism.

You might wonder why the researchers do not just try Lovastatin in humans with Fragile X.  Unfortunately, Lovastatin was never approved as a drug in Scotland, or indeed many other countries.  Some researchers just assumed they could substitute Simvastatin, which on paper looks a very similar drug and one that crosses the blood brain barrier better than Lovastatin.

Lovastatin, not simvastatin, corrects core phenotypes in the fragile X mouse model

The cholesterol-lowering drug lovastatin corrects neurological phenotypes in animal models of fragile X syndrome (FX), a commonly identified genetic cause of autism and intellectual disability. The therapeutic efficacy of lovastatin is being tested in clinical trials for FX, however the structurally similar drug simvastatin has been proposed as an alternative due to an increased potency and brain penetrance. Here, we perform a side-by-side comparison of the effects of lovastatin and simvastatin treatment on two core phenotypes in the Fmr1-/y mouse model. We find that while lovastatin normalizes excessive hippocampal protein synthesis and reduces audiogenic seizures (AGS) in the Fmr1-/y mouse, simvastatin does not correct either phenotype. These results caution against the assumption that simvastatin is a valid alternative to lovastatin for the treatment of FX.  

Although we propose the beneficial effect of lovastatin stems from the inhibition of ERK1/2-driven protein synthesis, it is important to note that statins are capable of affecting several biochemical pathways. Beyond the canonical impact on cholesterol biosynthesis, statins also decrease isoprenoid intermediates including farnesyl and geranylgeranyl pyrophosphates that regulate membrane association for many proteins including the small GTPases Ras, Rho and Rac [18, 46, 48, 49]. The increase in protein synthesis seen with simvastatin could be linked to altered posttranslational modification of these or other proteins. Indeed, although we see no change in mTORC1-p70S6K signaling, other studies have shown an activation of the PI3 kinase pathway that could be contributing to this effect [32]. However, our comparison of lovastatin and simvastatin shows that there is a clear difference in the correction of pathology in the Fmr1-/y model, suggesting that the impact on ERK1/2 is an important factor in terms of pharmacological treatment for FX.  There are many reasons why statins would be an attractive option for treating neurodevelopmental disorders such as FX. They are widely prescribed worldwide for the treatment of hypercholesterolemia and coronary heart disease [50], and safely used for longterm treatment in children and adults [46]. However, our study suggests that care should be taken when considering which statin should be trialed for the treatment of FX and other disorders of excess Ras. Although the effect of different statins on cholesterol synthesis has been well documented, the differential impact on Ras-ERK1/2 signaling is not well established. We show here that, contrary to lovastatin, simvastatin fails to inhibit the RasERK1/2 pathway in the Fmr1-/y hippocampus, exacerbates the already elevated protein synthesis phenotype, and does not correct the AGS phenotype. These results are significant for considering future clinical trials with lovastatin or simvastatin for FX or other disorders of excess Ras. Indeed, clinical trials using simvastatin for the treatment of NF1 have shown little promise, while trials with lovastatin show an improvement in cognitive deficits [28-30]. We suggest that simvastatin could be similarly ineffective in FX and may not be a suitable substitute for lovastatin in further clinical trials.

Conclusion

If you are treating Fragile X, best to start with Lovastatin and see if it helps.  In theory it might also help NF1 (Neurofibromatosis Type 1).

It looks to me that Atorvastatin also inhibits the relevant pathway and does much more besides that (PTEN, BCL2 etc)

Atorvastatin inhibits insulin synthesis by inhibiting the Ras/Raf/ERK/CREB pathway in INS-1 cells

What is Roche doing with FRAX486?

Brain Hypoperfusion in Autism & Cocoa

Today’s post is simpler than many earlier ones and is actionable.

A known feature of many neurological conditions like Alzheimer’s and dementia is reduced blood flow to certain parts of the brain.  In the medical jargon this is called hypoperfusion.

This reduced blood flow is also present in autism and is measurable by MRI.

We encountered epicatechin in early posts on cocoa flavanols.  It would seem that one of epicatechin’s many effects is to increase cerebral blood flow. 

Two chocolate companies, Mars (Cocoavia) in the US and Barry Callebaut (ACTICOA) in France, have developed high flavanol cocoa.  10 g of their cocoa contains about 1 g of flavanols and produces cognitive benefits; even a quarter of this dose gives the cardiovascular benefits.  Mars, in particular, are funding a great deal of research and have committed to a five year project with Harvard.  The high flavanol products are available today.

Brain Perfusion Anomalies in Autism

While most research focuses on Alzheimer’s and other types of cognitive impairment and memory loss, there are studies on brain perfusion in autism.

Cerebral perfusion abnormalities in children with autism and mental retardation: a segmental quantitative SPECT study.

  

Autism is a severe developmental disorder, the biological mechanisms of which remain unknown. Hence we conducted this study to assess the cerebral perfusion in 10 children with autism and mental retardation. Five age matched normal children served as controls. These cases were evaluated by single photon emission computed tomography (SPECT) using Tc-99m HMPAO, followed by segmental quantitative evaluation. Generalized hypoperfusion of brain was observed in all 10 cases as compared to controls. Frontal and prefrontal regions revealed maximum hypoperfusion. Subcortical areas also indicated hypoperfusion. We conclude that children with autism have varying levels of perfusion abnormities in brain causing neurophysiologic dysfunction that presents with cognitive and neuropsychological defects.

  

Significant hypoperfusion was observed at cortical and subcortical areas of brain in autistic subjects, suggesting that the structural abnormalities

of these brain areas may result in reduced cortical activity, thus causing dysfunction of these brain areas, and eventually producing some of the

emotional and behavioral disorders usually described in autistic subjects. These SPECT findings may help to explain several behavioral features of autism, such as impulsive and aggressive behaviours (to self and others), motor disinhibition (such as stereotypic and manneristic movements and echophenomena), and deficits in planning, sequencing and attention.

Abnormal regional cerebral blood flow in childhood autism

Neuroimaging studies of autism have shown abnormalities in the limbic system and cerebellar circuits and additional sites. These findings are not, however, specific or consistent enough to build up a coherent theory of the origin and nature of the brain abnormality in autistic patients. Twenty-three children with infantile autism and 26 non-autistic controls matched for IQ and age were examined using brain-perfusion single photon emission computed tomography with technetium-99m ethyl cysteinate dimer. In autistic subjects, we assessed the relationship between regional cerebral blood flow (rCBF) and symptom profiles. Images were anatomically normalized, and voxel-by-voxel analyses were performed. Decreases in rCBF in autistic patients compared with the control group were identified in the bilateral insula, superior temporal gyri and left prefrontal cortices. Analysis of the correlations between syndrome scores and rCBF revealed that each syndrome was associated with a specific pattern of perfusion in the limbic system and the medial prefrontal cortex. The results confirmed the associations of (i) impairments in communication and social interaction that are thought to be related to deficits in the theory of mind (ToM) with altered perfusion in the medial prefrontal cortex and anterior cingulate gyrus, and (ii) the obsessive desire for sameness with altered perfusion in the right medial temporal lobe. The perfusion abnormalities seem to be related to the cognitive dysfunction observed in autism, such as deficits in ToM, abnormal responses to sensory stimuli, and the obsessive desire for sameness. The perfusion patterns suggest possible locations of abnormalities of brain function underlying abnormal behaviour patterns in autistic individuals.

Cerebral Hypoperfusion and HBOT?

One therapy proposed to treat Cerebral Hypoperfusion in autism is hyperbaric oxygen therapy (HBOT).  Some proponents go as far as to link specific areas of the brain to specific autistic features as below.

The mainstream view, among those using HBOT for other conditions, is that it would not help stimulate increased blood flow in autistic brains.  But there are proponents of the therapy like Rossignol.

Hyperbaric oxygen therapy may improve symptoms in autistic children

You may have realized that the science exists to test, once and for all, whether HBOT can improve cerebral blood flow in autism.  It just takes two visits to an MRI.

Perfusion MRI Lab: How can we measure cerebral blood supply

I did see a report about a US neurologist who showed via MRI that the cerebral blood flow of his autistic patient improved using HBOT and he tried to use this to get access to the further HBOT on insurance.

Hypoperfusion in Alzheimer’s, Dementia  and Cognitive Impairment

Reduced cerebral blood flow is a marker of incipient dementia.  I expect one day this might even be used to trigger preventative therapy.

Cerebral hypoperfusion and clinical onset of dementia: the Rotterdam Study.

Abstract

Cerebral blood flow (CBF) velocity is decreased in patients with Alzheimer's disease. It is being debated whether this reflects diminished demand because of advanced neurodegeneration or that cerebral hypoperfusion contributes to dementia. We examined the relation of CBF velocity as measured with transcranial Doppler with dementia and markers of incipient dementia (ie, cognitive decline and hippocampal and amygdalar atrophy on magnetic resonance imaging) in 1,730 participants of the Rotterdam Study aged 55 years and older. Cognitive decline in the 6.5 years preceding CBF velocity measurement was assessed with repeated Mini-Mental State Examinations in nondemented subjects (n = 1,716). Hippocampal and amygdalar volumes were assessed in a subset of 170 nondemented subjects. Subjects with greater CBF velocity were less likely to have dementia. Furthermore, in nondemented subjects, greater CBF velocity was related to significantly less cognitive decline over the preceding period (odds ratio per standard deviation increase in mean CBF 0.74 [95% confidence interval, 0.58-0.98]) and larger hippocampal and amygdalar volumes. A low CBF is associated with dementia, but also with markers of incipient dementia. Although we cannot exclude that this is caused by preclinical neurodegeneration leading to hypoperfusion, it does suggest that cerebral hypoperfusion precedes and possibly contributes to onset of clinical dementia.

Vascular dementia

Vascular dementia is the second-most-common form of dementia after Alzheimer's disease.  It is a much simpler condition, it is dementia caused by problems in the supply of blood to the brain, typically by a series of minor strokes.

The incidence peaks between the fourth and the seventh decades of life and 80% will have a history of hypertension. Patients develop progressive cognitive, motor and behavioural signs and symptoms.

Blood pressure rises with aging and the risk of becoming hypertensive in later life is considerable

It would seem that you could treat hypertension and vascular dementia with the same preventative therapy.  See the clinical trial on treating vascular aging with Cocoa, later in this post.

It has also been suggested that endothelial dysfunction and vascular inflammation may also contribute to increased peripheral resistance and vascular damage in hypertension. 

In essence you want to control peripheral resistance and before it is too late.  It really is a case of “a stitch in time saves nine”.

The research done in to peripheral resistance / vascular stiffness can be re-purposed to help us treat brain hypoperfusion.  In autism we may have Brain Hypoperfusion, but without high blood pressure (hypertension).

Impact of cocoa flavanol intake on age-dependent vascular stiffness in healthy men: a randomized, controlled, double-masked trial

Increased vascular stiffness, endothelial dysfunction, and isolated systolic hypertension are hallmarks of vascular aging. Regular cocoa flavanol (CF) intake can improve vascular function in healthy young and elderly at-risk individuals. However, the mechanisms underlying CF bioactivity remain largely unknown. We investigated the effects of CF intake on cardiovascular function in healthy young and elderly individuals without history, signs, or symptoms of cardiovascular disease by applying particular focus on functional endpoints relevant to cardiovascular aging. In a randomized, controlled, double-masked, parallel-group dietary intervention trial, 22 young (<35 years) and 20 elderly (50–80 year) healthy, male non-smokers consumed either a CF-containing drink (450 mg CF) or nutrientmatched, CF-free control drink bi-daily for 14 days.

The primary endpoint was endothelial function as measured by flow-mediated vasodilation (FMD). Secondary endpoints included cardiac output, vascular

stiffness, conductance of conduit and resistance arteries, and perfusion in the microcirculation. Following 2 weeks of CF intake, FMD improved in young (6.1±0.7 vs. 7.6±0.7 %, p<0.001) and elderly (4.9 ± 0.6 vs. 6.3 ± 0.9 %, p < 0.001).

Secondary outcomes demonstrated in both groups that CF intake decreased pulse wave velocity and lowered total peripheral resistance, and increased arteriolar and microvascular vasodilator capacity, red cell deformability, and diastolic blood pressure, while cardiac output remained affected. In the elderly, baseline systolic blood pressure was elevated, driven by an arterial-stiffness-related augmentation.

CF intake decreased aortic augmentation index (−9 %) and thus systolic blood pressure (−7 mmHg;

Cocoa Flavanols

I did write an earlier post about the various benefits of Cocoa Flavanols. 

Why not Cocoa Flavanols for Autism?

  

Here is a very good review paper:-

The neuroprotective  benefits of cocoa flavanol and its influence on cognitive performance

Norman Hollenberg, at Harvard, has been an advocate of high flavanol cocoa for decades.  Here is one of his papers.

Cocoa and Cardiovascular Health

Using functional MRI, the following study measures the effect on brain blood flow, before and after taking a high flavanol cooca drink

Cocoa Flavanols and fMRI showing effect on Brain Perfusion

The effect of flavanol-rich cocoaon cerebral perfusion in healthy older adults during conscious resting state: a placebo controlled, crossover, acute trial

There is now good evidence that the acute benefits for cognitive function and blood flow exerted by cocoa flavanol consumption peak approximately 90–120 min postconsumption (Schroeter et al. 2006; Francis et al. 2006; Scholey et al. 2010; Field et al. 2011); however, it is presently unclear whether separate chronic mechanisms exists following cumulative consumption over several weeks and months, or indeed whether chronic consumption enhances the effectiveness of acute mechanisms in a cumulative fashion. Despite several plausible mechanisms for increased neuronal activity (as described above), it remains to be seen whether a single cocoa flavanol dose-induced increase in CBF is associated with concomitant benefits in cognitive performance in the immediate postprandial period. More broadly, recent reviews of acute interventions and epidemiological surveys provide good evidence that flavonoids and their subclasses are beneficial for cognitive function

In conclusion, the present findings support the hypothesis that flavanol-rich cocoa beverages are associated with increased CBF within a 2-h post-prandial time frame. More specifically, increased brain perfusion following the HF drink relative to the LF drink was observed in the anterior cingulate cortex and a region in the left parietal lobe. These data add to the substantial body of literature demonstrating that flavanol consumption is beneficial for peripheral and cerebral vascular function and thus for maintaining, protecting and enhancing cardiovascular health.

Does High Flavanol Cocoa have an effect in Autism?

This is probably the question you have been asking yourself.

I did acquire some ACTICOA, high flavanol cocoa some time ago.  I was wondering how I was going to administer enough of it to make a trial.  In the trials on improving memory in older adults 10g a day was needed.

While adding it to milk seems an obvious choice, Hollenberg suggests that the milk may neutralize the flavanols.  This is true with black tea; once you add milk you lose its healthy antioxidant properties.

In the end I choose to add 5ml to the breakfast broccoli powder and water concoction and mix with a frappe mixer.  Monty, aged 12 with ASD, was the ever willing test subject.

Two and a half hours later there was unprompted laughter and smiling.  This is repeated each time I give the ACTICOA  cocoa.

According to the literature, the peak level of epicatechin occurs 2 to 3 hours after consuming cocoa.

Then I tried a regular raw cocoa powder at the same dose; no laughter.

So I conclude that ACTICOA is indeed different to regular non-alkalized cocoa powder.  The more common alkalized cocoa has virtually no flavanols at all, and this is what is used to make most chocolate and is sold in supermarkets as "cocoa".

There are potentially other sources of epicatechin, but you really want a reliable standardized product.  If you live in the US/Canada this is easy; you can buy the Cocoavia product from Mars.  It is not cheap if you want 1g of flavanols a day.

The literature does suggest that there is a cumulative effect of taking epicatechin and Hollenberg has documented that regular consumption of unprocessed cocoa (rich in flavanols) is associated with numerous health benefits, particularly related to blood flow (strokes, heart attacks, endothelial dysfunction, cholesterol etc.)

Since Mars are now funding considerable research into the health benefits of these flavanols, I did think of suggesting they look at autism.

They could take a group of people with autism, measure their IQ and then score their autism using one of the standard scales.  Then off to the MRI to measure blood flow and velocity in different parts of the brain.

Give half of the test subjects a daily high flavanol drink and the other half a low flavanol drink.  After three months, repeat the IQ test, autism test and measure blood flow again via MRI.

I suspect that reduced blood flow/hypoperfusion would be more present in those with lower IQ and that they might show improved IQ at the end of the trial.  I suspect that in terms of autism, most would show an improvement on the high flavanol treatment.

I would like to think that after three months, blood flow/velocity would have increased.

You could then repeat on people with Down Syndrome and more general MR/ID.