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Blood-Brain Barrier Neurosciences Uncategorized

[Sciences/BBB] T Lymphocytes and Cytotoxic Astrocyte Blebs Correlate across Autism Brains (DiStasio et al., Ann Neurol 2019)

I  have been recently approached on social media to discuss about the recent study published by Anderson and colleagues in Annals of Neurology (https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.25610), in which the authors reported the presence of residing CD8 cytotoxic T-cells in the perivascular space of brain samples from ASD patients. I wrote about it, and gave my first impressions about reading the study. After such discussion, I realized that I have an interesting review that worth being shared here on my blog.
Here is the summary of my review of this paper as I wrote it on social media. I made some corrections (mostly spelling and grammar), as well as some changes in the writing style (I wrote these comments on the spur of the moment, as I went through the paper). Also due to copyrights, I will not show any figures and tables from the study.

About the authors: The first author is Dr. Marcello DiStasio (MD/PhD) and the senior author is Dr. Matthew P. Anderson, MD/PhD. He is a clinical faculty of Harvard Medical School and member of the Department of Neurology and Pathology a Beth Israel Deaconess Medical Center, with an affiliation with Boston Children’s Hospital Intellectual and Developmental Disabilities Research Center.  So we have some high profile and experts in neurodevelopment disabilities.

About the journal: The journal is published under Wiley, and is the official journal of the American Neurological Association and the Child Neurological Society. It has an impact factor of 9.49 and is in the top quartiles of neurology and neurosciences journal. Therefore, we have a study published in a very good journal that is relevant to the topic.

About the study design: The study is mostly observational and relies mostly on histological methods (tissue sections followed by staining using chemical dyes and/or antibodies targeting specific proteins). Tissue samples are freshly isolated from postmortem patients (which is a big plus compared to formalin-fixed samples, and opens up the ability to perform protein and RNA analysis if the samples are immediately treated for extraction). The sample size is pretty decent (N=25-30) with a large age spectrum and various types of ASD represented. First interesting to note, 50% of the ASD brain (N=25, not bad) have a history of seizures. Less than 30% of control brains (N=30) have history of seizures. Important thing to consider as a comorbidities and evenutally as a cofounding factor.

About the results: This is my summary of the different figures. By copyright concerns I am not showing the actual figures, but you can overlap my comments to the figures as I have separated them into sections.
Figure 1: Me being cranky, I wanted to see control brain pictures, but not avail. Also with immuno pictures, you have to be super-precautious because there is a high risk of cherry-picking a brain slice, and claim it is representative of all brain. Nevertheless lets discuss it here. On the left panel, we have an H&E staining. Pretty much a vanilla staining. Now, if you want to show a certain protein, you can do it with the right antibody and staining (DAB/peroxidase stain). It appears as the dark brown color. We can see a strong GFAP staining around the vasculature (hollow structure). Astrocytes usually line up blood vessels by forming end-feet process. S100B and ALDH1L1 are pretty standard proteins for astrocytes. However seeing GFAP expression in human astrocytes means these cells are stressed out and are reactive. This is what the quantitative bar graph is telling us. We can also see some CD8 in this perivascular space. These are the cytotoxic T-cells. I wonder what they are doing there, as they can cross the BBB only during brain injury, as microglial cells will äctivate” these endothelial cells and allow white blood cells to adhere on their surface and cross the BBB into a complicated tango dance.
Figure 2: Here there is an attempt of some matrix correlation. GFAP versus CD8 cells. And we can see there is some (expected) correlation between these two (see linear regression and R2) with ASD brains have higher rates of both compared to controls. Interestingly we see similar pattern between ASD that are genetic versus the idiopathic.
Figure 3: digs in more about the immune cells and some correlations (although the scatter of the ASD brains is less convincing here). Overall it seems we have a higher number of lymphocytes in the ASD brain compared to control, both in the white matter (WM, this is where our cables go through) and grey matter (GM, this is where our processing units are) and lepomeningeal (LM, this is our brain surface protective skin, basically the meninges, pours the CSF into the veinous blood). What seems interesting is that at young age we have lymphocytes sitting in our perivascular space, doing nothing(?) and decrease as we age (thats interesting for the non-neuroimmunologist that I am). However, these number at best slightly increase in ASD brain as we age (and I guess not convincingly enough, otherwise the authors would have reported the R2 value), or at least remain the same. With the exception of the medulla (brain stem) most blood vessels show a higher number in ASD brains versus control brains. Interestingly, cortical blood vessels being the predominant population harboring such feature. Very few NK cells to be honest on the panel.
Figure 4: Again this one makes me cringe a bit as a reviewer, because the author do not show the controls data. Yeah, I am pissed. Anyway. Again, perivascular space. Again immune cells highly present (CD3+), CD8 lymphocytes being the predominant type of T cells, in contrast not many CD4 lymphocytes (usually the T helpers, but my immunology is outdated for 20 years at least). Granzyme staining denotes the presence of natural killer (NK) cells. CD20 is a marker for B cells. What is interesting is mostly not much B-cells in either ASD and control brains, the graph more like a refried version of what we already know (higher number of immune cells and CD8 cells).
Figure 5:  is a bit of a useless graph, I don’t see anything that brings us more information than before.
Figure 6: It shows us a Masson trichrome staining. It is a chemical (histological) staining aimed to make collagen fibers visible under a certain color compared to other tissues. Collagens exist in different forms (based on their alpha-fibrils) but the one you expect to see around the vasculature is Collagen Type IV (COL4A1). This one forms a basement membrane (BM) that is like a net around blood vessels. Think about standing on a trampoline. Thats it. Collagen IV forms the net that supports the BBB. Normally, you would expect the BM to be thinned out, this is the case after stroke as cells secrete protein-degrading enzymes (like matrix metalloproteinases MMP2 and MMP9) that will break it down into pieces. But here it is thickened and hhad a bigger thickness than normally. Why so? What does not mean? I dont know. The only time I have seen such things was in transgenic mice overexpression erythropoietin (EPO). These mice had a such high hematocrit that would make blood be like Aunt Jemima corn syrup. If I remember, my former PhD adviser had a collaboration with an electron microscopist and observed similar thickening. Why this is happening is a good question that is likely the next study.
Figure 7: See Figure 5 comment.
Overall thoughts, limitations and outlook: Overall, it is very interesting study, that has some methodological limitations to be noted. First, we are missing any information about the BBB integrity in general, as I wish the authors would have shown some immunofluorescence to compare changes in tight junction (TJ) proteins expression (claudin-5, occludin) in blood vessels and assess differences in TJ strands. The second problem is the lack of information about microglia activation (that would be done by Iba1 staining. The authors noted they performed it, observed a higher expression in ASD brain but decided not to show the data) and more importantly the status of endothelial cell activation (using ICAM1, VCAM1 staining). Are these residing CD8 T cells freshly migrated or just being duck sitting for a while? Is the inflammation status in the brain (and the BBB) ON or OFF at the time of autopsy? What about pro-inflammatory cytokines levels between ASD and control patients? As usual, studies like that opens much more questions that it answers. The second problem is that the study by itself fairly descriptive and observational. It would be interesting how this would compare to clinical findings done in patients. Do we see flares on the MRI indicating of the BBB opening? How does that data compares to patients with MS?
I would also be very careful on making any claim about a “leaky” or “down-regulated” BBB at this point. There is no data about the barrier integrity (TJ complexes integrity) or assessment of the barrier function (for example an MRI scan with gadolinium as contrasting agent) to support the claim. I have seen this claim floating around in non peer-reviewed articles (including in The Scientist), as a BBB expert I would not jump into that conclusion quickly until I see real data on that
This is the type of interesting study, because it opens 100 questions that incentivize to further look down the road. I hope that the authors were able to prepare RNA and protein samples for transcriptome analysis (RNAseq) and proteome analysis (2D-electrophoresis coupled with MALDI) that could help us learn more.

 

 

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Blood-Brain Barrier Neurodegenerative diseases Neurosciences Stem Cells

[Sciences/BBB] X-linked adrenoleukodystrophy and blood-brain barrier: latest insights from preclinical and clinical studies

Two studies came out of interests in the last few weeks about the dysfunction of the blood-brain barrier in X-linked adrenoleukodystrophy (ALD): an in vitro study from Azarin and colleagues (I know Dr. Azarin as we collaborated on several publications together) using patient derived stem cells to model the blood-brain barrier in a dish (https://www.ncbi.nlm.nih.gov/pubmed/29615068) and a brief communication from clinical data showing an improved blood-brain barrier function (by MRI) in ALD patients treated with stem cells (https://www.ncbi.nlm.nih.gov/pubmed/30635285).

Before I go into details, I think it is important to discuss about ALD. ALD is a X-linked genetic disease (it affects mostly boys, as they carry only one copy of the X chromosome) affecting one in 18’000 patients and with a grim prognosis. It usually onset between 4-10 years old children, resulting in their rapid neurological deterioration and eventual death within 2-5 years. As of today, there is no treatment.

ALD pathophysiology is mainly occurring as a demyelinating disease. Myelin is a complex fatty acid acting as an insulant around nerves axons, by ensheathing such axons very similarly as a plastic insulant around copper wires in electrical wires.  In ALD patients, there is an abnormal processing of very long chains fatty acid (VLFCA), resulting in its buildup in the serum and in the brain white matter, resulting in abnormal immune response in the brain and neuroinflammation. About 50% of ALD patients will display a childhood cerebral ALD (ccALD), as displaying the clinical features mentioned. Because it is primarily a disease affecting neurons, a lot of research have been focusing on neurons and ignored non-neuronal cells.

These two studies add to the list of neurological diseases associated with ALD. First, the study by Azarin and colleagues (University of Minnesota-Twin Cities) show that brain endothelial cells (BMECs) differentiated from induced pluripotent stem cells (iPSCs) derived from ALD patients have a deficit phenotype compared to controls, have poorer barrier tightness and maturation. Moreover, they show that such BMECs have lipid inclusions (a cellular feature of lysosomal storage disorders) and express genes involved in inflammation at higher levels than controls. Interestingly, they also identified a polymer (PEO-PPO) can alleviate the dysfunction and partially restore the barrier function. It was interesting to see this study finally out, as I have seen the poster of it at the recent Gordon Research Conference.

Second, the study by Lund and colleagues (University of Minnesota-Twin Cities too) noted an improvement of the BBB (using MRI imaging and gadolinium as contrasting agent) in patients that received an hematopoietic stem cell transplant (bone-marrow transplant) as seen by a reduction in Gd leak by day 30 and improvement of patients outcomes. At this point, there is no clear evidence of how it works (the author speculate that some monocytes from the donor may migrate in the brain and attenuate the neuroinflammation) and if there are an overall improvement of the patient function.

Still, these two articles are interesting as it bring an insight of the contribution of the BBB in the ALD pathophysiology and further demonstrate the importance of the BBB as a contributing factor in several neurological diseases.

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Blood-Brain Barrier Junk Sciences Junk Sciences Neurosciences Sciences Uncategorized

[Sciences/Junk Sciences] Zeolites, blood-brain barrier and “Autism Detox” scam.

Recently, it came to my attention of another scam popped up on social media. This scam came in form of the “Autism Detox” page on Facebook coming with the following description:
IMG_2005

“Zeolite”, “blood-brain barrier”, ‘detoxify toxins and heavy metals” and “cellular level”.
Incredible how much amount of BS claims can be packed in such a small vaporizer. Not only this was enough BS, the owner of this page went the extra mile and claims it is an “autism detox” as well.
I call this an utter amount of BS and since I am a scientist, I will explain why it is an utter amount of BS.

1. What are zeolites?
Zeolites are crystalline structure made of aluminum, silicium and oxygen. These crystals are formed by the aggregation of 4 oxygen atoms around aluminum Al3+ and Silicium Si4+ (notice how Avers that yells “shark” on aluminum in vaccines are fine absorbing aluminum from zeolites).
These frameworks of AlO4 and SiO4 can form 3-D geometrical structures harboring charges and possibly acting as a caging structure as shown below (Moshoeshoe et al., Am J Mat Sci 2017):

As you can see different structures exist. Now, which zeolites are used in the product described in this “detox”? According to the vendor website (https://www.coseva.com/toxin-removal/advanced-trs/), clinoptilolite (CLI) (amongst water and a proprietary formula). According to Mosheoshoe and colleagues, CLI harbors the following chemical composition ((Na,K)6(Si30Al6O72) •20H2O)) and harbor the following crystalline structure:
Clinoptilolite

Notably, CLI also display one of the lowest cation exchange capacity (CEC) of 2-2.6 mEq/gram. In summary, CLI is a small zeolite crystalline structure with limited cation exchange (against Ca2+, K+ and Na+). First, it shows that these compounds have a molecular weight exceeding the size recommended for small molecules (~832 Da>500 Da), a ring size bigger than the tight junction pore (5.6 Angstroms>4 Angstroms) and an non-negligeable amount of molecular charges. All these features make CLI very unlikely to cross the blood-brain barrier and no studies have provided a direct experimental evidence that CLI crosses the BBB.

2. Does zeolites even cross the GI tract?

Good question! The only paper that I found discussing about zeolites is a paper from Cefali and colleagues (Cefali et al., Pharm Res 1995). Unfortunately I cannot access the paper but the abstract provides two important parameters: Cmax and AUC. In particularly, it also provides the value of aluminum hydroxide (yep, that stuff found in vaccines).
Cmax is indicative of the maximal concentration reached upon administration via extravascular route (IM, PO or SC). The AUC is representative of the total amount that reached the circulation from the time of administration until the time the drug becomes undetectable in blood. From the abstract we have the following information The mean plasma silicon AUC values (+/- S.D.) were 9.5 +/- 4.5 [Note: Zeolite A], 7.7 +/- 1.6, 8.8 +/- 3.0, 6.1 +/- 1.9 mg.hr/L [Note: Aluminum Hydroxide] and the mean plasma silicon Cmax values (+/- S.D.) were 1.07 +/- 1.06 [Note: Zeolite A], 0.67 +/- 0.27, 0.75 +/- 0.31, 0.44 +/- 0.17 mg/L [Note: Aluminum Hydroxide] for Zeolite A, sodium aluminosilicate, magnesium trisilicate, and aluminum hydroxide respectively. Although mean silicon AUC and Cmax values were elevated when compared to baseline after administration of the silicon containing compounds, only the AUC from Zeolite A reached statistical significance (p = 0.041). The mean plasma silicon Tmax values (+/- S.D.) were 7.9 +/- 6.4, 5.8 +/- 4.6, 6.9 +/- 6.3 and 8.5 +/- 3.4 hrs for Zeolite A, sodium aluminosilicate, magnesium trisilicate and aluminum Hydroxide respectively.”. Since we have a Cmax and AUC value for Zeolite A and aluminum hydroxide very similar, we can assume that both compounds may likely show similar bioavailability. Considering the bioavailability of Al is very low (0.3%), it is very likely that zeolite and CLI may not show a higher value that this one. Thus, out of 100g ingested of zeolite, maybe less than 0.3g will likely reach the bloodstream. In conclusion the amount of zeolite capable to cross the GI is very small and considering the volume of a TRS “Detox” (28mL), the amount of zeolite capable to cross the GI tract after swallowing a whole bottle of it is likely to be ZERO.

3. What about the rest of the claims?
As far we have seen:
1) CLI absorption at the GI tract is likely close to ZERO, even if you sip a whole bottle at once (see 2).
2) CLI cannot cross the BBB because of the physicochemical constrains (see 1). The only paper listed in Pubmed is a letter written to a journal with no scientific evidence or experimental data backing up the claim (https://www.ncbi.nlm.nih.gov/pubmed/23224491).
3) The claim of detox is utterly BS: there are two organs that do it for you. The liver and the kidneys. Thats it.
4) Heavy metal detox mostly occurs via renal (kidney) filtration. Even if zeolites can trap ions like Na+ or K+, I still have to find a paper that shows me it can trap heavy metals (Cd2+, Pb2+, Hg2+…..). CLI has been shown to only trap three ions (Ca2+, Na+ and K+) with the poorest ability.
5) Claiming that autism be cured is not fallacious but criminal. Until now, there is no cure for autism. There is no evidence that chelating ions cure autism (chelation therapies have even been proven to be dangerous and responsible for the death of at least one boy). There is also no published mechanism of action demonstrating how a treatment can reverse a condition mostly identified as genetic.

 

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Blood-Brain Barrier Neurosciences Sciences Uncategorized

[Neurosciences/BBB] Brain Endothelial Erythrophagocytosis and Hemoglobin Transmigration Across Brain Endothelium: Implications for Pathogenesis of Cerebral Microbleeds (Chang et al., Frontiers Cell Neurosci 2018)

I usually don’t post BBB papers on my blog because most of the time they address concepts or answers questions that are not relevant for the public in general, but I thought this one was an interesting paper to share. This is an original article published by Rudy Chang and colleagues in Frontiers in Cellular Neuroscience las month. It is open-access, that allows everyone to access to it. Another interesting feature is the disclosure of the reviewers that help improve the peer-review process and transparency.
Why I found this paper interesting? Its because it propose a novel mechanism of cerebral microbleeds, without affecting the tight junction complexes. In the field, when we consider brain bleeds, we consider a loss of the barrier function and a massive brain leakage. Such phenomenon occurs when you have an hemorrhagic stroke due to an aneurysm, or due to a arterioveinous malformation resulting in an unstable blood vessel. The presence of blood in the brain parenchyma is harmful for two reasons:
1) You are injecting a volume inside a closed space (cranium) that will lead to an increased mechanical pressure (intracerebral pressure) and ultimately brain damage by tissue crunching.
2) Red blood cells (RBCs) may be damaged (hemolysis) and release their content into the extracellular space. Heme is toxic at high concentration (through mechanisms that yet to be identified) and can further damage neurons via generations of free radicals and other damage-inducing signaling pathways.
In this article, they demonstrate that you may achieve a similar outcome than brain bleeds without having a leaky BBB. In particular, this study demonstrate the ability of damaged RBCs to cross the BBB via transcytosis (via an engulfment inside the BBB and the exit to the other side). For this study, they used bEND.3 cells (an immortalized mouse brain endothelial cells) and compared mouse RBC that were considered healthy or induced damage via tert-butylhydroperoxide (t-BHP). t-BHP induces oxidative stress (via the release of radical oxygen species such as hydroxyl radicals), in this case leading to the exposure of a particular phospholipid named “phosphatidylserine” (PS) from the inside to the outside of the cell surface membrane.
In this study, they demonstrated that oxidative stress mattered in RBC cell adhesion to b.End3 cells. Treatment of b.End3 cells with t-BHP or LPS (a bacterial membrane lipid, commonly used to induce an inflammation state at the BBB) failed to yield similar results. in addition to demonstrating the ability of RBC to adhere on b.End3 cell surface (the first step needed for cellular transcytosis), they also demonstrated the ability to have these cells to engulf and get trapped into these cells. This process appeared slow and it took about 18-24h to see a significant number of RBCs inside the cells. Finally, they show that such RBCs were capable to migrate through the b.End3 monolayers and popped out in the other side. Similar outcome was observed in vivo, but to a certain extent.
It is a very interesting study, because it can maybe explain some aspect of diseases associated with RBCs such as cerebral malaria (we can imagine that Plasmodium may use RBCs as a Trojan horse to cross the BBB). However, I also have some criticism of the study. First, it uses the b.End3 that has fairly poor barrier function (TEER<100Ohms.cm2), much less than the tightness expected in vivo (>2000Ohms.cm2). The second issue is inherent to working with non-human cells. Do we have the same outcome when it comes to the human BBB and human RBCs? Maybe this phenomenon is exclusive to rodents and may have limited impact in humans. Finally, and as seen with the in vivo data, RBCs maybe able to cross the BBB but they maybe likely get retained by 1) the basement membrane supporting brain endothelial cells and 2) rest in a limbo state in the perivascular space (a virtual space between the basement membrane and an external protein mesh called “glia limitans” wrapped around cerebral blood vessels). We have some hints as RBCs appear juxtaposed near the vasculature, as stuck by a mesh surrounding the vessels. I don’t think that RBCs can cleave such mesh because I assume they don’t have the molecular machetes (matrix metalloproteinases) to cut their way through. Yet, I think it is a very interesting paper, that work to be investigated with a human BBB model, using a more robust model.

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Blood-Brain Barrier Junk Sciences Junk Sciences Neurosciences Sciences Uncategorized

[BBB/Autism/Junk Sciences] Autism, bleach and the blood-brain barrier: how the CD/MMS cult is promoting child abuse on bogus scientific claims.

I have been blogging about quack medicine, charlatanisms and debunking claims about the blood-brain barrier for few years now. But nothing reach the level of indignation and anger than the treatment reserved for children diagnosed as “on the spectrum” (for autism spectrum disorder or ASD), especially those treated with the “CD/MMS protocol” aka “the bleach protocol”, as recently discussed in various blogs and in news outlet here and there.

Introduction:

“Autism spectrum disorders” that is an umbrella medical definition that is defining children presenting deficiencies in social skills, a particular focus on patterns or objects including certain rituals or organization (e.g. sorting toys by their colors, lining cars in a perfect order, bed linen to be perfectly folded), hyper-sensibility to environmental cues (sounds, light, colors….) and in some cases neurodevelopment or communication delays. Not all autistic children are equals, with very different types of syndromes or conditions (e.g. Asperger’s Syndrome, Rett’s Syndrome……).

Although the etiology of ASD is deeply anchored into genetics as a major risk factor (followed by neuroinflamamation during gestation due to infectious diseases), the diagnostic still remains flexible and have been standardized only recently through the “Diagnostic and Statistical Manual for Mental Disorders”, currently in the fifth edition. Such standardization is as recent that a notable number of adults often get diagnosed “on the spectrum” late in their life, often during their adulthood.

Until now, there is no therapies to address such condition and mostly involves medication for treating other conditions associated with the disease (epilepsy is often diagnosed in children on the spectrum) or behavioral therapy (also known as applied behavioral analysis).

Because the diagnosis of autism is perceived and feared amongst parents and the lack of therapies are obvious, such environment creates a fertile ground for charlatans and snake oil seller preying on fear to make profit, selling parents a “cure-it all” potion or interventions, using these children as “guinea-pigs” by pushing protocols or treatment that are best have poorly fared in the scientific literature (most of the time published in low-impact factor journals) if not completely bogus.

A few example of such doubtful or quack remedies are dietary restrictions (gluten-free/casein-free diets), injection of biologics (GcMAF), if not dangerous interventions such as the use of hyperbaric oxygen treatment or use of chelation therapy. But amongst them reside one of the worst treatment: the CD/MMS protocol, or as we should call it the “bleach protocol”.

The CD/MMS protocol: a fancy name for a bleach protocol targeting autistic children

CD stands for chlorine dioxide (O=Cl=O) a bleaching agent used mostly for industrial purposes. CD shares similarities with the household bleach (O=Cl-) and both as referred as chlorinated bleaching agents.

Until recently, Kerri Rivera has been actively promoting the CD/MMS protocol as a “cure for autism” through her book co-authored with other charlatans named “Healing The Symptoms Known As Autism”. in this book, they promote the use of CD via ingestion of droplets or via enema administration. Such aggressive chemical is enough to damage the mucosal layer lining the luminal wall of the gastrointestinal (GI) tract and its detachment. Such detached mucosal layer is often labelled as “parasites” which indeed any respected parasitologist will quickly debunk such fallacious claims.  Kerri Rivera promotes the use of this protocol to cure “autistic children” and up until recently was promoting such treatment in the Autism One conference. She discussed in details about this protocol on the Chapter 8 of her book and makes disturbing claims about the blood-brain barrier.

Fallacious things Kerri Rivera said about the blood-brain barrier in her book:

The first fallacious claim from Kerri Rivera appears on Chapter 3, pages 48 and 49. In this chapter, she promotes the gluten-free/casein-free/soy-free diet as a treatment for autism with the excuse of the “leaky gut syndrome” as the following: “This results in poor digestion, which facilitates the entry of these harmful proteins [gluten and casein] directly into the bloodstream, where they can cross the blood-brain barrier.“. I never heard about gluten and casein crossing the BBB, especially considering that these are large peptides and therefore have to use transporters and receptors. Of course, her claims is not backed by a reference to a study.
Then she refers to this ” Improperly digested gluten and casein fragments can both enter the bloodstream and cross the blood-brain barrier. Because of their opioid properties, these peptides can react with opiate receptors in the brain to cause effects similar to those of an opiate drug such as heroin or morphine.7 These opiates are called gluteomorphin (or gliadorphin) and casomorphin, and can react with some parts of the brain, for example, the temporal lobes, which are actively involved in the process of the integration of language and hearing. Interestingly, these are two of the areas most affected by autism.

She cites this page for her claims. Interestingly, if you look at the page this claim is based on making a parallel between celiac disease and a speculation and hypothesis as cited: “Now in terms of autism, the situation is somewhat different because children with autism generally do not have celiac disease and do not have the DQ2 genotype problem. Whereas the problem of celiac disease is well proven in scientific studies, the problem with gluten sensitivity in autism is less well studied. The autism hypothesis involves, like celiac disease, the toxic effects of small peptides, generally in the range of five to seven amino acids in length (termed casomorphin and gliadorphin, as noted below). It is believed that these peptides from gluten, as well as certain peptides from cow milk protein (casein), can somehow cross the intestinal microvillus barrier and reach the blood stream.”

In a previous edition, Rivera went further and cited two papers to back her claims (now this claims has been watered down and put in the FAQ section of this chapter):  a study from Reichelt1 and colleagues and a  review from Shattock and colleagues2. Firstly, the citation of Shattock review is outdated and only provide an exhaustive overview of published studies supporting or dismissing the theory of opioid-excess. It has no scientific value as it does not provide a direct evidence of such claim. More troublesome is the following study led by Hunter and colleagues published by Hunter and colleagues in 2003 investigating the presence of opioids mimetics in patients urine and published in Developmental Medicine & Child Neurology3, a journal with an acceptable impact factor (IF=3.29). Using liquid chromatography coupled with mass-spectrometry (a common analytical technique used for measuring metabolites in biological fluids), the authors have investigated the presence of opioids in a cohort of 10 children with ASD and used siblings as controls. Interestingly, the authors failed to notice notable differences (as defined by presence of unique peaks) in the urine chromatogram of ASD children compared to controls. The authors further investigated the presence of opoid peptides previously cited by Shattock, in particular beta-casomorphin (a peptide byproduct obtained from casein degradation) and alpha-gliadin (a peptide byproduct obtained from gluten degradation). The authors failed to identify the presence of both peptides, based on retention time compared to standard or based on the m/z index.  This publication irated enough Shattock to be followed  by a comment to Editor and a scientific joust between Shattock and Hunter4, however an  editorial published by John F Mantovani resumes well the context in which the initial statement of Shattock was published5. At this time, ASD etiology was completely unknown and remained highly speculative. The publication (and subsequent retraction) of the so-called “Wakefied study” 6 linking MMR vaccines to ASD cases, but also documenting the presence of inflammatory bowel disorder in ASD patients, such condition is known to triggered by gluten and casein in patients suffering from celiac diseases. As Mantovani mentioned, the adoption of the theory of gluten and casein was correlating with the same approach than the vaccine without any scientific rationale. The study from Hunter indeed showed the lack of evidence about the claim made by Shattock. The amount of studies linking autism and exorphin remains very low. A query on Pubmed (the database of the National Library of Medicine) using the keywords “autism” and “exorphin” results in only 7 publications with 3 publications from Reichelt, KL and two publications from Brudnak, MA.
This brings the concern of data reproducibility. In order to have a scientific claim that have strong significancy you need two factors: a significant number of publications that investigated such statement and the publications of findings from different research groups. Having the monopoly of such investigation solely on a single research laboratory raises the issue of data reproducibility and reliability.
In this case, the study of Reichelt is very interesting, as its publication quality appears dubious at different levels. The journal of Microbial Ecology and Health Disease has recently adopted the “open-access” policy. Prior its publication as open-access, the journal has an 2013 unofficial impact factor of 0.933. The “open access” and the low IF raise red flags: such journal may be a potential “predatory journal” (a term coined by Retractionwatch.org, a website tracking scientific articles retraction). In this model, the cost of open-access is levied by the payment of hefty publication fees ($3000-5000) usually higher than subscription-based journals. Because of such financial gain, the peer-review process may be altered and even may be completely omitted, removing the quality control accomplished by peer-review. This lack of peer-review process is particularly blatant by the absence of clearly structured “methods” sections, odd wordings for a scientific (“ELISA typed as Elisa, thaw over night, eight-hundred microliters”), the source of samples (Association Planet Autism (Italy), samples from Slovenia, Serbia and Australia) and the overall format of the paper figures with some appearing as a screenshoot of a Powerpoint presentation or from printed copies. It raises some skepticism about why the author (based in Norway) failed to collect samples from Norwegian ASD patients.

In the previous edition, Rivera linked these studies to a “leaky bowel syndrome”. A major flaw in this claim is the absence of citing the original publication for Hsaio and colleagues7 that have demonstrated the presence of a “leaky gut syndrome” in mice showing an ASD phenotype. Instead Rivera cites the Gluten Free Society webpage as a source of information (http://www.glutenfreesociety.org/gluten-free-society-blog/dr-fasano-on-leaky-gut-syndrome-and-gluten-sensitivity/).

Dr. Alessio Fasano is certainly a respected researcher in celiac diseases but as noted with pseudoscience and activists groups lacking the scientific knowledge, cherry-picking and extraordinary extrapolation. In particularly in this case by the Gluten Free Society, those as their Facebook webpage mentions, identify themselves as alternative and holistic health society. This is again a red flag on the mission and purpose of this society that have little or no scientific evidence to support their claims except deviating, cherry-picking and reformulating genuine studies to push for their agenda.

Under normal conditions, the intestinal and the blood-brain barrier (BBB) (Figure 1) provides a tight cell monolayer creating a gut-blood and a blood-brain barriers respectively. Under normal conditions, such barrier is achieved by the presence of tight junctions complexes stopping the diffusion of electrolytes and water between the two compartments. Only digestion byproducts such as amino-acids or glucose are transported through dedicated nutrient transporters or solute carriers, whereas bigger entities such as peptides, proteins and pathogens have virtually no diffusion). Only lipids (fatty acids, cholesterol…) and drugs (designed as lipid-soluble chemicals) can passively diffuse across the barrier by mixing themselves with the phospholipid bilayers making the cell membranes.

Picture1

In the study from Hsiao, the authors demonstrated indeed the presence of a “leaky gut” as measured by an increase in FITC-dextran permeability with an estimated size of 4kDa (that’s about the size of a peptide of 36 amino acids). Even is such peptides can cross a “leaky gut”, they still have to cross the BBB. Some scientific studies have demonstrated the biological activity of opioids analogs obtained from digestion byproducts, including gluten and casein. Yet, a review from Lister and colleagues 8 denoted that a majority of these studies were based on intracerebroventricular (ICV) injections (or intracranial). This drug delivery approach allows to bypass the BBB but also is a very invasive approach that is used in clinical settings only for emergency and severe cases.

If such peptides were to cross the BBB and exert the biological activity discussed by Rivera, they have to have a dedicated peptide transporter that can deliver such peptides from the blood to the brain side. The number of peptides capable to cross the BBB has been recently reviewed by Banks 9, a well-established BBB scientist in the transport and delivery of peptides and inflammatory cytokines across the BBB. There is no mention about any of the opioids mentioned by Reichelt or Shattock publications. Furthermore, the increase in gut permeability appears unlikely or indirectly related to gluten or casein-sensitivity, as the authors demonstrated a change in the gut microbioma, in particular changes in Bacteorides fragilis as well as changes in metabolites discovered in serum plasma. However this study has to be taken with a lot of precaution due to the differences related to interspecies variation, the behavioral representation of mice to model ASD and more importantly, similar studies in human patients investigating samples from stools and plasma levels to observe if similar trends or biomarkers are noted in humans.

The next chapter that talks about the BBB is the Chapter 5, in which she discussed about the use of CD/MMS protocol, claiming to hunt their imaginary parasite inside the brain as mentioned by the following: ” In early 2011, we added enemas to the protocol to kill the pathogens causing dysbiosis in the large intestine (we didn’t know about parasites yet). We wanted to get the chlorine dioxide into the blood stream so it could kill the biofilm that exists in the blood. In this way, the blood can carry the CD past the blood-brain barrier to kill pathogens in the brain
When we are detoxing, it is absolutely critical to keep the colon moving and avoid the reabsorption of toxins through the intestinal walls. Enemas allow us to do just this. Some toxins can exit the intestine through the intestinal wall (more so if leaky-gut syndrome is present), and cross the blood-brain barrier, therefore affecting cognition and behavior. When we cleanse the colon, we get those out before they can cross into the brain, and we detoxify the lymphatic system, liver, and gallbladder.
The following argumentation of Rivera is very interesting as she is referring to Dr. Andreas Kalcker and the parasites at the base of her bleaching-based therapy. Let’s first identify Dr. Kalcker. According to his official biography (http://www.andreaskalcker.com/en/biography.html), he studied economics in Barcelona and has earned a Ph.D. in biophysics and alternative health without mentioning his alma matter. This is very puzzling, as any genuine Ph.D. holder will mention the institution that granted his/her degree. Furthermore, the deliverance of a Ph.D. in biological and biomedical sciences (and I believe in any scientific domains) requires the publication of at least one publication in a peer-reviewed journal. Notably, the search of Dr. Kalcker publication in either Pubmed (NLM) or in Sciencedirect (Elsevier) database leads to inconclusive results. At this stage, his Ph.D. degree claim is highly doubtful and raises concern about the credentials of Andreas Kalcker to hold such title.
The main question that can arise is on which expertise Dr. Kalcker discusses about autism, parasites, blood-brain barrier and nutrition? The author of this critique has 11 years of scientific research experience in the blood-brain barrier, 15 peer-reviewed publications.
The gut-brain axis is still a fairly new concept in the BBB field. Up to now, there is only one study that have demonstrated the beneficial effects of gut microbioma on the BBB development during gestation 10 and requires more studies to further confirm this single report. Furthermore, ASD diagnosis and mechanisms of disease have highly progressed since the original retracted publication of Wakefield and colleagues. It is now a consensus that ASD is triggered by two major factors: a genetic and an environmental factor11-14.
The current consensus is the predominance of the genetic factor that set the risk of ASD development and different factors in particular exposure to environmental toxins may trigger the onset of the condition. This second aspect is very interesting, as the penetration of such toxins across the BBB is poorly understood and believed that the presence of efflux drug transporters and phase II metabolism enzymes would void the penetration of such compounds across the BBB and target neurons. Such statement is supported by the ability of the BBB to act as a very strong barrier towards xenobiotic (drugs and toxins), we estimate than less than 5% of current drugs are capable to cross the BBB. The presence of such BBB is a main challenge for drug delivery 15, 16. However, scientific literature yet has to demonstrate how such environmental polluants mar the BBB and how they may affect brain development during gestation that leads to the ASD onset.
Therefore, we can reasonably ask the following question:

  1. On which scientific basis Kelly Rivera supports the claim of parasitic infection? There is no published scientific literature supporting her claim.
  2. Furthermore, under which expertise and scientific literature Dr. Kalcker built his theory on the improper digestion?

According to the Merriam-Webster Dictionary (http://www.merriam-webster.com/dictionary/theory), the definition of theory is “the analysis of a set of facts in their relation to one another”. Neither Kerri Rivera nor Dr. Kalcker have the credential to set a theory because there is no scientific facts to support their theory.

Therefore their tentative to explain their rationale is deeply flawed and should be considered as wrong until a significant number of studies with the adequate scientific quality and neither Rivera or Dr. Kalcker have demonstrated the credentials to exercise a diagnosis or establish a treatment regimen and are legally unlicensed to practice medicine (diagnosis) or pharmacy (treatment) and may face severe legal issues to do so.

The most compelling fact of Rivera and Dr. Kalcker are their active participation in the sell of MMS and CD as a treatment from autism. Such behavior is a clear sign of conflict of interest, a modern form of snake oil sell and a deliberate act of poisoning. Such misuse of public trust and poisoning has lead to the arrest of Dr. Kalcker in Spain in 2014 as reported by the bancdmms website (http://www.bancdmms.com/#!about1/c157n) as well as pro-MMS groups.

In conclusion, until now there is not direct evidence of a gut-brain axis interaction triggering ASD is until now a fallacious statement. There is no clear evidence of such statement, only a series of meticulous cherry picking studies from predatory journals and retracted articles. The direct evidence of gluten and casein peptides in ASD patients is weak and doubtful and would requires a substantial re-evaluation of such claims until other independents research groups demonstrates similar outcomes under controlled conditions.

Furthermore, the etiology of ASD as presented by Rivera and Dr. Kalcker is pure fallacy as none of them have the expertise, credentials and the scientific evidence to make such claims but also have deliberately ignored a sustained and solid publication records concerning the diffusion of peptides across the BBB and the etiology of ASD as a neurological disorder with a high genetic background (supplemented by an environmental factors).

Because the etiology of ASD at this time remains elusive, the treatment of ASD by medication remains until now undocumented, even using pre-clinical models. Only an early diagnosis and intervention by behavioral therapy have been proven successful to improve behavioral and social outcome in ASD patients.

Using common tactics of pseudoscience to distract a non-scientific literate audience, Rivera shows her ability to build an argument on fallacious statements with a an obvious conflict of interest (the endpoint is to sell her MMS/CD cure), as well as a documented harmful outcome of such treatment.

References:

  1. Reichelt KL, Tveiten D, Knivsberg AM, Bronstad G. Peptides’ role in autism with emphasis on exorphins. Microb Ecol Health Dis 2012; 23.
  2. Shattock P, Whiteley P. Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention. Expert Opin Ther Targets 2002; 6(2): 175-83.
  3. Hunter LC, O’Hare A, Herron WJ, Fisher LA, Jones GE. Opioid peptides and dipeptidyl peptidase in autism. Dev Med Child Neurol 2003; 45(2): 121-8.
  4. Shattock P, Hooper M, Waring R. Opioid peptides and dipeptidyl peptidase in autism. Developmental Medicine & Child Neurology 2004; 46(05).
  5. Mantovani JF. Not knowing. Developmental Medicine & Child Neurology 2003; 45(02).
  6. Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, Malik M et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 1998; 351(9103): 637-41.
  7. Hsiao EY, McBride SW, Hsien S, Sharon G, Hyde ER, McCue T et al. Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell 2013; 155(7): 1451-63.
  8. Lister J, Fletcher PJ, Nobrega JN, Remington G. Behavioral effects of food-derived opioid-like peptides in rodents: Implications for schizophrenia? Pharmacol Biochem Behav 2015.
  9. Banks WA. Peptides and the blood-brain barrier. Peptides 2015.
  10. Braniste V, Al-Asmakh M, Kowal C, Anuar F, Abbaspour A, Toth M et al. The gut microbiota influences blood-brain barrier permeability in mice. Sci Transl Med 2014; 6(263): 263ra158.
  11. Fakhoury M. Autistic spectrum disorders: A review of clinical features, theories and diagnosis. Int J Dev Neurosci 2015.
  12. Correia C, Oliveira G, Vicente AM. Protein interaction networks reveal novel autism risk genes within GWAS statistical noise. PloS one 2014; 9(11): e112399.
  13. Pinto D, Delaby E, Merico D, Barbosa M, Merikangas A, Klei L et al. Convergence of genes and cellular pathways dysregulated in autism spectrum disorders. American journal of human genetics 2014; 94(5): 677-94.
  14. Rossignol DA, Genuis SJ, Frye RE. Environmental toxicants and autism spectrum disorders: a systematic review. Transl Psychiatry 2014; 4: e360.
  15. Cucullo L, Aumayr B, Rapp E, Janigro D. Drug delivery and in vitro models of the blood-brain barrier. Curr Opin Drug Discov Devel 2005; 8(1): 89-99.
  16. Abbott NJ. Blood-brain barrier structure and function and the challenges for CNS drug delivery. Journal of inherited metabolic disease 2013; 36(3): 437-49.

 

Categories
Blood-Brain Barrier Sciences Uncategorized

[Sciences/BBB] About the Thanksgiving tryptophan comatose and the BBB

Happy Thanksgiving everyone, I hope you are enjoying your family gathering. I know many of you are dreading to meet the family and extended family to discuss about controversial topics and differences in opinion.
But the other big menace coming in, that is particularly feared by the Black Friday shoppers: “The Thanksgiving turkey comatose” myth. This myth is perpetuating the idea that the Thanksgiving feast will induce a lethargic state attributed to the tryptophan present in turkey. Lets use this time to talk about tryptophan, turkey and of course the BBB in all that.

1. What is tryptophan?

Tryptophan is one of the 22 amino acids forming the building bricks of each of our proteins. It belongs to one of the few amino acids that our body cannot produce and therefore has to get it from our food supply.
In addition to its role in proteins, tryptophan is also an interesting molecule for the central nervous system, because it serves as a precursor for serotonin (a neurotransmitter also known as 5-hydroxytryptamine) and melatonin (commonly known as the “clock hormone”). You can see the similarities in structure of these molecules below:
Picture1

Tryptophan is particularly enriched in meat. According to the USDA, turkey meat contains the highest level of tryptophan from all foods, followed by white eggs, soybean and seaweeds. This partly support the claim of turkey being rich in tryptophan.

2. How does the tryptophan enters the central nervous system?

Like you expect, the blood-brain barrier is impermeable to any charged molecule. This is the case of many amino acids circulating in the blood (pH=7.4). Thus amino acids can enter the brain only by using special “revolving door” called solute carriers (SLCs). Tryptophan is transported by a particular amino acid transporter called large amino acid transporter 1 (LAT1). LAT1 is a particular transporter because it is formed by two subunits named SLC3A2 (also named CD98) and SLC7A5.
LAT1 is not specific to tryptophan, it also allows the transport of other aromatic amino acids like phenylalanine and tyrosine, but also chained amino acids such as leucine or arginine.

The impact of dysfunction in LAT1 remains poorly understood, however a study by Mykkaenen and colleagues noted several point mutations in SLC7A7 with a rare disease named lysinuric protein intolerance, a rare autosomal disease primarily described in patients from Finnish and Japanese origin marked by the impaired transport and elimination of basic amino acids following a protein-rich diet.

3. What is the function of tryptophan in the brain?

As I have previously mentioned, tryptophan is the precursor of two major neuromediators: serotonin and melatonin.
Serotonin is produced by a certain type of neurons named “serotoninergic neurons”. Like other neurons expressing a particular neurotransmitter other than glutamate or gamma-aminobutyrate (GABA), these neurons are restricted to a certain localization usually referred as “nucleus” (kernel, core). These neurons can project their axons all through the brain via a process called projections, allowing these neurons to interact with far-fetched neurons localized in a remote location.

In the case of serotoninergic (5-HT) neurons, these neurons are located in a structure called “raphe nucleus” and project to areas in which such neurotransmitter interact with 5-HT receptors. Through the interactions with the receptor, serotonin plays an important role in the modulation of several behavior including appetite, emotional (depression, anxiety), cognitive (schizophrenia) motor and autonomous (for instance emesis, the scientific term of “puking“).

In addition to the biological effects on the brain, the serotonin system is also linked to the circadian rhythm system (what we can call the “biological clock”) as depicted in the picture below:

sadserotoninfigure

We are diurnal animals as our main activity occurs during daylight and concludes with our sleep cycle during the dark period. In opposite, some animals like rodents are nychthemeral animals (active during dark phase and sleeping during daylight).

The light/dark cycle phase is determined by our eyes and retina. Such retina will transmit the presence of light to a particular nucleus named “suprachiasmatic nucleus” (SCN) . This nucleus is consisted by cells and nuclei functioning as oscillators. You can think about a pendulum in perpetual movement or a ticking clock. When darkness settles, the retina start to slowdown the information coming to the SCN.
In turn, the SCN becomes less active and relieve the blockade of the activity of the pineal gland. The pineal gland in turn start to secrete melatonin (aka the sleep hormone) that act as a “negative feedback loop” further shutting down the SCN and stimulate the production of serotonin via the raphe nucleus. All these events ultimately giving us the feeling of being sleepy and the process of sleeping.

4. So why we claim the “turkey comatose” is real?

As you can see in this myth, we are facing a post-hoc ergo fallacy. “I feel sleepy after Thanksgiving dinner. I ate large amount of turkey meat at Thanksgiving dinner. Turkey contains tryptophan and sleep is controlled by melatonin (a tryptophan derivative). Thus the tryptophan contained in the turkey meat is responsible of the food comatose”.

As you have seen, this does not make sense as the sleep/wake cycle is driven by the light exposure. This is also explaining partly why some people feel more tired and less motivated during winter times.

One explanation we can discuss is the particular food intake we all face during Thanksgiving that exceed our usual amount of food. We rarely experience such a feast and copious meal during the year. The table is furnished with so different plates, rich in proteins and carbohydrates.
This create a spike in food intake and food digestion that will likely create a urge of blood flow towards the gastrointestinal tract. This physiological phenomenon is named “postpandrial torpor”, making you feel sleepy and tired after a large meal, even if the meal was completely turkey-free.

So in conclusion, if you want to avoid “the turkey comatose”, don’t blame it on the turkey. Blame it on your eyes having a bigger appetite that your stomach can sustain. Keep it in moderation and now you know about the tryptophan transport at the BBB.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Categories
Blood-Brain Barrier Neurosciences Uncategorized

[Sciences/BBB] Acute Necrotizing Encephalitis (of childhood), a blood-brain barrier perspective.

This is a blog post following a request by a page follower on my Facebook account to provide an “layman” perspective on acute necrotizing encephalitis (ANE), also referred as acute necrotizing encephalitis of childhood (ANEC). This is a very short and surely incomplete summary but it should be a great starter to give the current perspective of this condition through the lens of the blood-brain barrier.

It is a condition that was firstly discovered by Mizuguchi and colleagues in 1995 firstly described in infants and toddlers (http://jnnp.bmj.com/content/jnnp/58/5/555.full.pdf). It was firstly described in patients from Asian origin (Japan). It was initially described to occur during the winter period, in particular with region that had experienced an influenza A outbreak. The main clinical feature of the disease marked by the presence in the magnetic resonance imaging (MRI) of increased water content inside the brain, mostly associated with edema (brain swelling). This increased water content can only be explained by the opening of the blood-brain barrier.

Water diffusion between the blood and the brain is tightly regulated by the blood-brain barrier (BBB). The BBB provides two kinds of barrier: a physical barrier (by the presence of tight junctions) and a chemical barrier (by the presence of solute carriers and drug efflux pumps). The case of water as a molecule (H2O) is very interesting. Water is a very small molecule (the molecular weight is 18g/mol or also 18 Daltons) but also a very polarized molecule. Hydrogens and the oxygen atoms forming H2O are not completely neutral, hydrogen carries a tiny positive-charge and oxygen carries two tiny-negative charges (we refer in chemistry as electronegative charges). Think about having a tiny magnet. In the opposite, cell membranes are made of phospholipids. As their name say, they are lipids by definition or what we commonly call them as “fatty acids”. Lipids have a distinct composition, they are mostly formed by carbons and hydrogens. Carbon is not much a magnet atom, it neither likes to carry positive charges nor negative charges. This is why lipids are commonly referred as apolar molecules. Now, polar and apolar molecules behave like water and oil mixed together: they simply do not mix and will sequestrate themselves, usually forming a oil droplet surrounded by water. Water entrance inside the brain is believed to occur mostly via paracellular route, as depicted in the picture below (source: http://www.nature.com/nrn/journal/v7/n1/full/nrn1824.html?foxtrotcallback=true).

main-qimg-a138eec8624c78aa6379a71b994b20ac-c

Tight junctions are very tights, letting water fall through the cracks only in a tiny amount. Imagine having a very good rooftop that only let water fall through one drop every hour. The problem with the opening of the BBB following various factor is the massive entrance of water. Think about having a hole in your rooftop and facing a tropical storm shower outside: you are facing now a massive and unregulated entrance of water inside the brain, leading to a brain swelling.
In peripheral tissue, edema (swelling) formation can naturally expand, resulting in a swollen tissue. The problem with the brain is its anatomical structure: it is encased inside a rigid shell (skull) that has no exit route for the penetrating water. This results in an increased pressure inside the brain (we usually referring as increase in intracranial pressure or ICP). This increased pressure induce a mechanical stress, crushing brain cells via mechanical stress and ultimately neuronal cell death. Such swelling appears to occur in specific brain regions, with a primary lesion site in the gray matter (neurons), with persistent deposition of hemosiderin and white matter (axon fibers) cysts during and after the recovery phase. Until now, we don’t exactly know what cause such disease, but appears as following a viral infection including flu (influenza A and B, swine flu (H1N1), parainfluenza virus), varicella, measles, rubella and various herpesviruses (HHV-6, HHV-7) (https://www.hindawi.com/journals/mi/2015/792578/#B1), although the presence of such viral agents (detection by polymerase chain reaction) in spinal tap as well as post-mortem signs of brain inflammation remains anecdotal.

Interestingly, it seems that patients suffering from ANE undergo a very severe immune response commonly referred as “cytokine storm”, as several studies noted an increase in inflammatory markers (in particular interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha (TNF-alpha) making this phenomenon the most prevalent hypothesis.

Immune cells communicate to each other via a common language called “cytokines”. Cytokines are like a “RED ALERT” system, they signal some breach in security or incoming danger.
Brain microvascular endothelial cells (BMECs) lining the blood side of the BBB can also understand the “cytokine” language and understand such signal as “RED ALERT – OPEN THE BBB SIGNAL” as depicted in the picture below (source: https://www.researchgate.net/profile/Nicolas_Weiss/):

Now where are these cytokines coming from and how they are triggered? It is a very good question. This is where the viral infection comes in. I will not details much about the immune response to viruses, but you can ask @TheMadVirologist for any questions related to viruses. For this I will use a figure that resume the immune response to viruses (source: https://www.researchgate.net/profile/Francoise_Stoll-Keller/).

figure-1-function-of-dendritic-cells-in-the-immune-response-to-virusesfollowing-the

Upon infection, infected cells will display viral particles on the cell surface and will also secrete a protein called “interferon-gamma”. This is a sort of cellular “SOS Danger” to the immune system. Natural killer cells, dendritic cells and macrophages may start the early response, also known as “innate immunity” to contain the viral infection. In addition, free circulating viruses can be spotted by B cells through their array of surface antibodies and trigger what we refer to as “acquired immunity”. Viral infection will trigger an immune response and we can think that maybe an overactive immune system may exaggerate the danger resulting into the “cytokine storm”. Another hypothesis is that such cytokine storm maybe triggered by natural killer (NK) cells.

This hypothesis is further supported by the presence of a higher count of natural killer leukocytes in ANE patients during the recovery phase. Natural killer (NK) cells are immune cells normally targeting cancer cells and cells infected by viruses.  This “cytokine storm” maybe the causative agent of the blood-brain barrier disruption (BBB) by different mechanisms (source: http://stroke.ahajournals.org/content/strokeaha/42/11/3323/).

but appears to occurs via an matrix-metalloproteinase (MMPs) dependent pathway. Under the stimulation of such cytokines, brain endothelial cells and astrocytes may increase the production and releases of MMPs locally. These MMPs act as little scissors that can chop the extracellular matrix supporting brain endothelial cells and astrocytes end-feet processes. In addition, these MMPs can also chop tight junction proteins that are involved in tight junction (TJ) complexes. These TJs are very important as they provide the barrier limiting the diffusion of water and solutes between the blood and the brain.

In addition to the cytokine storm hypothesis, it seems that other factors maybe involved in the pathophysiology of the disease. Until now, Ran binding protein 2 (RANBP2) (http://www.cell.com/ajhg/fulltext/S0002-9297(08)00630-7). RANBP2 is a protein involved in the nuclear pore complex, yet the relevance of this mutation at the blood-brain barrier remains unknown. In neurons, it is associated with cellular structures different from the cell nucleus, in particular it is associated with mitochondria (power house of cells) and microtubules.

Another protein of interest associated is EphB2, a receptor for ephrins (https://www.ncbi.nlm.nih.gov/pubmed/?term=ephb2+blood-brain+barrier). Ephrins play an important role in brain wiring during development (axon guidance) but also play a role in the formation of the vascular tree.

The function of EphB2 and ephrins at the blood-brain barrier remains unclear. However, a recent study identified the expression of EphB2 at the cell surface of endothelial cells including primary human non-BBB (HUVECs) and BBB (HBMECs) endothelial cells. Furthermore, a case report from a patient suffering from systemic lupus erythromatous (SLE), an autoimmune disorder, presenting the case of ANE showed the presence of antibodies in the serum capable to bind selectively to EphB2.

Yet, at this point we don’t know if this antibody binding is enough to trigger the BBB disruption or it requires the recruitment of immune cells to trigger such disruption.

 

 

 

 

 

 

 

 

 

Categories
Blood-Brain Barrier Junk Sciences Sciences Uncategorized

[BBB/Junk Sciences] Polysorbate 80 and the BBB or how to put anti-vaxxers into a blowing cognitive dissonance

Here we go again, anti-vaxxers keeping on moving the goalpost to fit their belief instead to change to adjust it to the facts. First it was mercury, then it was formaldehyde, then aluminum, today the “ingredient du jour” is polysorbate 80 and tomorrow they will blame it to PBS saline solution.

The latest fad as I have seen is to blame polysorbate 80 as a source of “vaccine-injury” with the bold claim that it breaks down the blood-brain barrier (BBB). Lets put the fact straight and debunk this one for all. But what is even better is the “what if” counter-argument. What if polysorbate 80 was indeed a good ingredient? I will come to that later.

Polysorbate (aka Tween 80) is a amphiphile compound   as you can see the molecular structure below (source Wikipedia):
1200px-polysorbate_80

You can see the structure made of a lipophilic (loves fat) tail and a series of hydrophilic  (loves water) tails, loaded with oxygen and hydroxyl groups. This is a typical structure of a detergent: one side will mix well with water, the other will mix very well with fat and oils. The result? You can form microspheres that can dissolve well in water and dissolve fat into water. This is how a detergent works, it helps to breakdown fats into small spheres and dissolve them in the drain water.
Polysorbate 80, due to this property, is very good to dissolve drugs and medicines that under normal condition would barely dissolve into biological fluids. This is why we have it in vaccines, but we also have it in medicines. Thats the job of biopharmaceutics: finding formulations to dissolve drugs into the body and allow them to reach a concentration high enough to display their therapeutic activity.

The use of polysorbate 80 in drug delivery of anti-cancerous drug is probably the first and foremost main driving factor on investigating its effect on the BBB. Brain tumors (primary and metastatic alike) are up until now one of the most dreaded and deadliest form of cancer. For instance, the average expected lifespan upon diagnosis of a grade IV glioma (aka glioblastoma multiforme) is grim: 18-months, with less than 5% survival after 5 years. The major issue is being able to deliver drugs and chemotherapy across the BBB. As reported by Pr. William Partridge (UCLA) the BBB remains the bottleneck in drug development for the treating neurological disorders (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539316/?fref=gc&dti=873247819461536)

The first report of the investigation of polysorbate 80 on the BBB is probably by Spiegelman and colleagues in 1984 (http://thejns.org/doi/pdf/10.3171/jns.1984.61.4.0674), investigating the effect of the solvent used in etoposide solution for treating cancer. According to their  result, they noted a statistical difference in the BBB permeability  (using Evans Blue and 99mTc as tracers) following the injection of 1.125ml/kg. According to their paper, 5mL solution contained 400mg of polysorbate 80 or a concentration of 80mg/mL. Based on this, we can assume that the BBB effect was observed for a dose of 90mg/kg. Thats a very huge dose.
If we go back to the manure anti-vaxxers say, the amount injected via vaccines is enough to cause a barrier opening. According to John Hopkins University Institute of Vaccine Safety (http://www.vaccinesafety.edu/components-DTaP.htm), the expected concentration of polysorbate is lesser or equal to 100mcg or micrograms. Thats 0.1mg per dose. If we assume such dose is injected to a newborn (average weight ~3 kgs), then the amount injected is about 0.033mg/kg. Thats 2700 times less than what has been reported to induce a BBB disruption. Also you have to factor the bioavailability of polysorbate (that is 100% upon IV route) making this number a very optimistic number.
Now, the interesting twist about polsyorbate 80 is its use to enhance some drug carriers and its widely used for finding novel formulation to enhance the delivery of anti-cancerous drugs across the BBB. You can find a list of publications on Pubmed about that aspect (https://www.ncbi.nlm.nih.gov/pubmed/?term=polysorbate+80+blood-brain+barrier). What if polysorbate 80 not only will not injure your brain, but actually may help deliver drugs to help your brain fight disease?

 

Keep in mind that polysorbate 80 is good at dissolving lipid in water solutions but it is not good to let charged molecules accross the BBB, just in case someone comes with the claims that it conjugates with aluminum. Thats some high-school chemistry level.

 

 

Categories
Blood-Brain Barrier glut1 deficiency syndrome Uncategorized

[Neurosciences/BBB] 8th GLUT1 Deficiency Conference – Summary

IMG_0272

Today wrapped the second and last day of the 8th GLUT1 Deficiency conference that was held in Nashville, TN this year. It was my second time I am attending this conference and honored to be a guest speaker this year.

 

The whole conference took place at the Inn at Opryland, part of the Gaylord Resort at Opryland. It is a fairly impressive complex with shuttle to the Opry Mills outlet shopping center and, the Gaylord Resort & Convention Center (in which the AACP is also holding a meeting starting today but I am just attending one day meeting there).

According to the organizers, we had about 220 attendees, with 68 families present. What I liked this year was the blending between parents, healthcare providers and scientists. In the previous conference, the first day was family and healthcare providers and the second day was the professional day. This allowed a unique interactions, questions & answers and discussion.

IMG_0016IMG_0031

 

It was also a very good time for updating my knowledge on the disease. Not much on the basic science, but more on the current treatment and dietary intervention with various experts of the field including Pr. Jorg Klepper (University of Essen, Germany); Pr. Juan Pascual (UT Southwestern, Dallas, TX); Pr. Eric Kossoff (John Hopkins University, Baltimore, MD) and other scientific experts.
19990402_1597989686907543_171023206372782768_n

My learning from the conference is that the disease in an evolutive disorder. We learn more about the disease as we learn from the patients growing in. As the patient grows, he or she displays different symptoms: “funny eyes movements” during infancy, presence of absence seizures during toddler times and learning attention and deficit during early school age, presence of movement disorders in both during childhood and adulthood and migraines, hemiplegia and “writers hand fatigue” syndrome. This seems to be linked by an impaired glucose uptake in the cerebral cortex and the thalamus.  It also seems that there is at some point in the disease the presence of a sexual dimorphism, as female patients seems to experience in their teenage years a “paroxysmal dystonia” that seems triggered by moderate and vigorous exercise. So, the GLUT1DS is not a static disorder. It is a disorder evolving over time with its clinical manifestations evolving as well.
The second thing I learned is the variety of “ketogenic diets”. There is not one single “keto diet” but several variants with different dosages and variety, including a Modified Atkins Diet.

IMG_0033IMG_0035

It seems there is not a “one size fits all” but rather different types of diets that also seems to vary with age.

IMG_0019IMG_0021

The younger age appears to need the following of a strict keto diet and as the patients age, some softening and flexibility can be introduced. It seems the critical time for the keto diet is infancy and childhood. The earlier the child is introduced, the better. There are also several companies providing cookbooks, supplements like keto powders or kets-friendly products aimed for patients.

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In terms of diagnosis, some interesting news came from a French biotech startup that can measure GLUT1 levels in RBC within 24 hours using a proprietary cell assay (that looks like an antibody assay) using a flow cytometry-based approach.
Another interesting result is the outcome of the ketogenic diet for GLUT1DS patients. For the vast majority of GLUT1DS patients (95% of patients), the keno diet significantly decrease the number of seizures by at least 50%. In contrast, other types of epilepsies combined only show a 50% of patients showing a responsive outcome to keto diet. Still, 5% of GLUT1DS do not respond to keto diet and there is a fraction of patients that show a normal glucose CSF levels and/or GLUT1 expression. We certainly have a lot of patients that undergo undiagnosed or misdiagnosed for years as “drug-refractory epilepsies”. But it seems that some patients maybe falsely diagnosed as GLUT1DS. Hopefully, with the decrease in price for DNA testing (it seems 23andMe can detect some GLUT1 SNPs) may help to broaden the diagnosis and identification of patients.
Some interesting topics presented at the conference was some possible drug adverse effects reported in G1D heterozygous mice in particular to diazepam and phenobarbital but also other drugs. Some parents noted the anecdotical adverse reactions following certain treatment. However, the absence of studies directly investigating such drug adverse effects in G1D patients most of the time go under the radar, with the health practitioner attributing it to the disease condition rather than some particular drug adverse effects. Having from screening tools can greatly help.
Another interesting presentation is the study of G1D heterozygous mice. These mice seems to display a lower brain vascular density compared to wild-type. This is not surprising considering the recent work of Pr. Peter Carmeliet (Universidaed Leuwen, Belgium) on endothelial cell metabolism. According to Pr. Carmeliet, brain endothelial cells highly depend on glycolysis to function despite being in presence of plenty amount of oxygen levels.
There have been also discussion of trying to setup a comprehensive guide for parents for a consensus on GLUT1DS diagnosis and management that can help them as a source for documentation during their visit with their doctors. There is also a discussion of improving the community outreach to professionals and politicians to improve the funding and the recognition of GLUT1DS as a condition, discussing about supporting open-access options for certain papers allowing parents a free-access to these new studies and also finding ways to support GLUT1DS awareness and management among minority populations and in other geographic areas (especially South America).
The person missing at this meeting by his presence was certainly Pr. Daryl DeVivo (Columbia University, New York, NY). Little patients left him some very kind words and their name on a paper board. I found it was a very cute gesture and remembered us that his absence was felt.
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The interesting silver lining comes from Europe, as they have set now a sister association that held their first European GLUT1 meeting last fall and plan to hold it in London in 2018 and in Paris in 2020.
For me, I am looking forward to attend the 2019 meeting in Washington DC and hopefully bring on some more breaking news from my lab there.

 

 

 

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Blood-Brain Barrier Stem Cells

[Stem Cells/BBB] Modeling Psychomotor Retardation using iPSCs from MCT8-Deficient Patients Indicates a Prominent Role for the Blood-Brain Barrier

Vatine et al. show that human iPSC-based modeling can pinpoint the origin of a neuronal disorder in the brain as a defect in transport of thyroid hormone across the blood-brain barrier, rather than in the neurons themselves.

Source: Modeling Psychomotor Retardation using iPSCs from MCT8-Deficient Patients Indicates a Prominent Role for the Blood-Brain Barrier