[Sciences/BBB] Why the vitamin K shot in newborn matters

I have seen the topic of vitamin K (VitK) shot coming over and over in various discussion groups, with some parents weighing the need of the VitK in newborns. One of the main argument in favor for the injection of VitK in newborn is its ability to reduce the risk of cerebral bleeding (cerebral hemorrhage).
I thought a post on this topic would provide a great help in understanding the physiological role of VitK, the consequence of brain hemorrhage and conclude on the importance of the VitK shot.

1.What is the vitamin K?

Vitamin K is a fat-soluble vitamin that is mostly obtained by our gut microbiota and accessory from our food intake (in particular leafy greens and liver).

220px-Phylloquinone_structure.svg

During gestation, the fetus obtains it from the mother, as such vitamin passes through the placenta barrier. Vitamin K plays an important role through its biochemical cycle called “the Vitamin K cycle”. Vitamin K can convert glutamyl residues present in proteins into gamma-carboxylglutamyl residues as depicted in the picture below:

F1.large

Such modified glutamyl residues are present in particular set of proteins called “coagulation factors”. These coagulation factors are important pieces of what we refer as the “coagulation cascade”.
400px-coagulation_full-svg

I know this graph is complicated but what we care here is the final part of the cascade. The presence of intrinsic damage or trauma, we have the activation of several coagulation factors. Amongst those that are VitK-dependent, we have factor VII (seven), IX (nine) and X (ten). Prothrombin, upon activation by factor X  is converted into thrombin, which in turn cleaves the soluble fibrinogen into the insoluble fibrin. Fibrin acts as a mesh and forms a fibrin clot that will patch the bleeding area. This is an important physiological response when you rupture a blood vessel. The coagulation cascade will create a clot that will stop the bleeding process, saving you from a risk of loosing too much blood and entering an hypovolemic shock. One organ is particularly sensible to brain bleed, this organ is the brain.

2. Brain hemorrhage: small numbers, big damage

In this section, I will mostly discuss about brain bleeds in regards of hemorrhagic stroke but you can apply the same pathophysiology to brain bleeds induced by brain trauma. Brain bleeds are the second type of stroke. They account for about 15% of total stroke events, but account for 40% of stroke-related deaths.

subarachnoid-800x416

We have different types of brain bleeds. In stroke, we usually have a type of brain bleed called “intracerebral hemorrhage” (ICH) that happens deep inside the brain. There are other types of hemorrhage called “sub-arachnoid hemorrhage”. In that case, the brain bleeds occurs in the sub-arachnoid space, a space between the brain and the skull. This type of bleed results into an ischemic stroke (due to a lack of blood perfusion in blood vessels beyond the bleed site) and a brain swelling (resulting in the crushing of the brain tissue due to increase intracranial pressure).

During the injury heme (from damaged astrocytes, neurons and red blood cells) is released in the extracellular space. Heme is a very strong pro-oxidant molecule resulting in the formation of radical oxygen species (ROS) such as anion superoxide (O2*-) and hydrogen peroxide (H2O2), which in turn further induce oxidative stress and cellular damage.

The major type of cells that suffers of such damage at the greatest extent are neurons. Neurons are highly sensible to such injury and unlike other cell types neurons do not divide anymore (post-mitotic cells). A dead neuron is a dead neuron. There are some studies suggesting a possible regeneration of neurons in certain brain regions in rodents (mice, rats), yet the presence of an evidence pointing out at similar mechanism in humans are yet to be demonstrated. Furthermore, there is still no evidence that stem cells (including cord blood stem cells from umbilical cord) can provide a repair of such brain region following injury.

As of today, a dead neuron is a dead neuron. The ability of a damaged brain region to recover is very limited.

3. Why Vitamin K shots?

As we just have explained here, we know that VitK is essential in coagulation and we also understood the impact of brain bleed on the brain. Thus, reducing such brain bleed can be done in the short-term by the induction of the coagulation cascade.
As we mentioned, babies get their VitK from the placenta, but by the time they are born, they are already coming with a low VitK. We also mentioned that the VitK is primarily produced by the gut microbiota. It will take weeks if not months for babies to get a gut microbiota that is functional enough to produce the VitK (I speculate that such microbiota is not present until the age of 12 months when baby eat a diet similar to adults). We can speculate that food (breast milk or baby formula) should provide a source of VitK but providing a steady and standardized intake from dietary is near impossible to achieve.
Furthermore, there is no lab tests or techniques that can predict the onset of a brain bleed. Furthermore, brain bleed has a very high mortality rate and very high morbidity rate including cerebral palsy and other brain damage.
Therefore, ensuring a source of VitK right at birth is the best approach to ensure the baby has enough VitK to have a functional coagulation cascade. In case of a brain bleed, we can expect to have a rapid response of the body to ensure a emergency clotting process ongoing until the doctors can intervene and stop such bleeding to happen and clean any possible brain bleed.
This is why it is important to opt-in for a VitK shot. Once a brain tissue is damaged, there is no evidence yet that there is regeneration of such area. Neurons do not divide anymore by birth and there is no evidence yet of stem cells (including stem cells from cord blood) able to repair such damage.

 

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[Neurosciences/Aluminum] Does the latest paper from Exley show a link between ASD and aluminum?

Someone brought my attention today about the most recent Exley paper out in the press titled “Aluminium in brain tissue in autism” (the title could have been better but well….) and published in the journal “Journal of Trace Elements in Medicine and Biology“.
Let me put this straight, this is not a paper that has evidence of scientific fraud or data manipulation. There is no duplicated images, no suspicious blots. The problem I have with this paper is its deep experimental flaws and data analysis that nonetheless should not have passed through the peer-review filter.

  1. Before we dive into the paper, lets put the paper into context
    Lets just put the paper in the context. It was received on October 26th (Thursday). Came back in its revised form on November 21st on Tuesday and accepted for publication on November 23rd (Thanksgivings for the US, but since the editor-in-chief (EIC) is in Europe no Thanksgiving here). Let that sink it a bit: in a bit more than three weeks, it got send to review, came back from review and got revised in 26 days. In my standard of reviewing for journals and publishing my papers, thats some faster-than-light peer-reviews. I usually wait 4-5 weeks by the time I submit mine and get the editor reply to my submission with the infamous reviewers comments. Does a fast-reviewed manuscript means a bad manuscript? Not necessarily, but it can mean that maybe the peer-reviewed was not optimal, rushed or even worse just botched. Based on the quality of the data presented, I am leaning towards a botched review. Thats quite disappointing because the journal holds a decent impact factor (~3 for 5-year impact factor) and you expect an okay review.
    Then comes another problem. Exley published this paper (as well as few others) in the journal…..in which he holds a seat in the editorial board. Nobody can exclude the possible conflict of interest. Consider that: if you were an EIC, would you provide the same rigor and objective decision on a paper submitted by a colleague sitting in your editorial board than a paper submitted by Doe and colleagues?
    Not forbidden, but if you can avoid it, avoid it. Transparency is key and publishing in diversified journals (unless it is society-official journals) is an indicator of an healthy research.
    Finally, the last thing to keep in mind before I deconstruct the paper is the funding source. According to the acknowledgment section “The research is supported by a grant from the Children’s Medical Safety Research Institute (CMSRI), a not-for-profit research foundation based in Washington DC, USA.”  Behind the fancy name is just another anti-vaccine foundation that will play “the vaccine safety” card to peddle their pseudosciences. So we can claim that Exley is a shill for CMSRI, since he received monetary support for his research. Does that mean the research is completely bogus? No, but it means it will require further scrutiny, especially when the claim of the study goes against the consensus in the field (aluminum in vaccines is safe).
    Same goes if a study funded by Big Tobacco claimed the absence of correlation between lung cancer and smoking or if Big Sugar claimed the absence of correlation between type 2 diabetes mellitus and consumption of sweetened beverages.
  2. So what is wrong with this paper?
    For those who wants to read the paper with me, you can download it here (I assume it is open-access, so you should not have an issue with the paywall). Exley has a publication record on aluminum, especially when it comes to its possible ecotoxicity and the impact of aluminum on certain biological processes.
    The introduction is damn short, half a page of a double-spaced document but set the tone, this study will investigate the relationship between autism and aluminum in the brain.
    Samples are obtained from the Oxford Brain Bank, but felt short to indicate the source of the tissue (like a catalog number) and how this source of materials was complying with the institutional review boards (IRB). Basically, for any research involving human subjects or human tissues, you have to comply with the IRB that such specimens are used for a certain and defined use and foremost been anonymized.
    We have 5 patients that were diagnosed as on the autism spectrum and immediately we can pinpoint an important issue: there are no controls and that’s one of the big and unforgiving flaw of this paper.
    The authors then used two techniques to localize and quantify the Al in different cortical regions (and sometimes hippocampal regions). They have used three technical replicates (random sampling from the same cortical lobe) for measuring the Al content using an atomic absorption spectrometry and used lumogallion (aka4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid, a fluorescent dye initially described to localize Al in plant roots). This dye have an excitation/emission spectra close from FITC/Alexa Fluor 488. It has been also used for live cell imaging , in particular to study how macrophages process Al present in vaccines adjuvants (http://www.sciencedirect.com/science/article/pii/S0022175915001222).
    Considering the equipment mentioned in the method, the microscope used provides the right excitation bandwidth filter and provide a long pass emission filter for anything over 510nm.Then things get weird, in the result sections, the authors mention the following:”We examined serial brain sections from 10 individuals (3 females and 7 males) who died with a diagnosis of ASD and recorded the presence of aluminium in these tissues (Table S1).“Where is the number coming from? Why don’t we have the same numbers in the Materials and methods?The other problem is the over interpretation of the data. To be brief, the lumogallion will show some punctuated pictures. The authors show some brightfield pictures overlapping to show the tissue structure but does not really help the reader. A DAPI stain (to stain cell nuclei) as counterstain would have been much more informative, it would helped to distinguish background noise from possible Al inclusion. Again, keep in mind we have no controls. The other issues with immunostaining is the high risk to cherry pick the data. You will be naturally inclined to show the presence of a positive risk but this cannot be used for quantitation. Thus, the use of the second method is welcomed as a complementary technique.
    For those not familiar with fluorescence, there is an important notion to keep in mind when analyzing the data: ensuring you keep the same exposure time, the same brightness or contrast and foremost have a negative control to set your exposure time. You can see a sketch explaining here on one of my fluorescence staining (based on my data, I concluded the expression was weak if not negative).

    Slide2

    The background subtraction is also a bit weird. I acknowledge the assessment of autofluorescence is a good control, but you expect to see a low staining. But foremost, you cannot overlap two distinct slices, as proximal as it can be. For instance, in Figure 1, you see some lumogallion staining and below the fluorescence  from the “control” using the adjacent slice. The lumogallion also seems to have a very high background.
    Picture1
    It seems lipid-rich environment increase dramatically the fluorescence of lumogallion (if you look at the spectra, the dissolution of the dye in Triton-X100 solution (b, a detergent) dramatically increase the excitation and emission spectra compared to water (a)).
    What I found troubling is this sentence in the results section: “We examined serial brain sections from 10 individuals (3 females and 7 males) who died with a diagnosis of ASD and recorded the presence of aluminium in these tissues (Table S1). Excitation of the complex of aluminium and lumogallion emits characteristic orange fluorescence that appears increasingly bright yellow at higher fluorescence intensities. Aluminium, identified as lumogallion-reactive deposits, was recorded in at least one tissue in all 10 individuals. Autofluorescence of immediately adjacent serial sections confirmed“.
    If you are a bit a fluorescence microscopy savvy, you know that the “emission color” we see in the objective is never caught by the CCD camera. These camera have in the most majority a B&W output for the simple reason that they have a much higher sensitivity than color cameras. You can always re-create colors in the micrograph pictures using various “lookup tables” (LUTs) that will give a pseudo color based on the level of grays. This is very useful when you samples different excitation/emission channels (for instance, samples stained with DAPI and two antibodies, one conjugated with Alexa Fluor 488 and the other with Alexa Fluor 546 or further down).
    The problem inherent with fluorescence is you can make thing fluoresce or end up with a false-positive signal if you increase the light beam (usually never happens because it is set) or if you increase the exposure time of your camera (this is the most common issue). As you increase exposure, you increase the risk to capture non-specific signal like autofluorescence signals.
    The other problem here is how to explain this sudden shift from orange to yellow?  This seems more like a subjective observation than something caught on camera.  That can be due to different things. You can have some bleed-through of the dye that is normally emitting in a certain wavelength but if it is strong enough can appears in neighboring emission channels. This thing rarely happens with a good fluorescence microscope that have defined filter cubes that allows the diffusion of certain emission wavelengths (for instance, my microscope have a DAPI, Alexa Fluor 488 and Alexa Fluor 555 cubes that only let the respective emission wavelengths  with 20nm-margin error to cross through the objective and reach the camera and binocular).
    Usually, we have to deal with bleed-through when you use flow cytometry and usually is solved using fluorescent dyes latex beads and by following a protocol called “compensation” (this has the result of removing any noise and keeping only the signals).
    We cannot also exclude that such fluorescence is just an autofluorescence from lipofuscine inclusion bodies. Lipofuscin is a lipid-based compound naturally produced by our cells. It has an important concentration in the central nervous system, however it is normally cleared out by cells. Failure in the clearance of lipofuscin is associated with different diseases called “lipofucsinosis” such as Batten’s disease. Even the author admit the possible presence of lipofuscin inclusions “Intracellular aluminium was identified in likely neurones and glia-like cells and often in the vicinity of or colocalised with lipofuscin (Fig. 5).” Lipofuscin is also capable of autofluorescence, although it is more in the wavelengths matching DAPI. Lipofuscin has an excitation/emission peaks at 360 and 435nm respectively but has been reported to also show fluorescence at 510nm when excited at 488nm (https://www.sciencedirect.com/topics/neuroscience/lipofuscin).
    Compared to the lumogallion excitation/emission spectra (507/567), we cannot exclude the presence of a phenomenon called “FRET” (Fosterman Resonance Energy Transfer) in which the excitation of lipofuscin (as the microscope excitation bandwidth is 470-495nm) provide enough energy to the photons emitted by the lipofucsin to excite nearby lumogallion dyes. Because the microscope setting used in this paper has no restricted bandwidth (it let pass any photons harboring a wavelength of 510nm and more), it may explain this orange-to-yellow transition noted by the author. The presence of a DAPI nuclear stain would greatly helped to identify this region as grey matter (rich in cells) or white matter (rich in lipid-rich myelin sheets). Thus, we can legitimately questions the nature of these as it these punctae labelled as “Al inclusion” are simply lipid inclusion or some artificial noise due to the tissue processing. This is where controls come as critical, it can help you sort the signal from the noise.

     

    The second big issue with this paper is the over-interpretation of what the experimenter see. The experimenter wants to see Al inclusion in monocytes? So be it: “Aluminium-loaded mononuclear white blood cells, probably lymphocytes, were identified in the meninges and possibly in the process of entering brain tissue from the lymphatic system“. Or maybe these are astrocytes, or neurons, or microglial cells, or blood vessels….or whatever the author wants to believe in: “Aluminium could be clearly seen inside cells as either discrete punctate deposits or as bright yellow fluorescence. Aluminium was located in inflammatory cells associated with the vasculature (Fig. 2). In one case what looks like an aluminium-loaded lymphocyte or monocyte was noted within a blood vessel lumen surrounded by red blood cells while another probable lymphocyte showing intense yellow fluorescence was noted in the adventitia (Fig. 2b). Glial cells including microglia-like cells that showed positive aluminium fluorescence were often observed in brain tissue in the vicinity of aluminium-stained extracellular deposits (Figs. 3&4). Discrete deposits of aluminium approximately 1m in diameter were clearly visible in both round and amoeboid glial cell bodies (e.g. Fig. 3b). Intracellular aluminium was identified in likely neurones and glia-like cells and often in the vicinity of or colocalised with lipofuscin (Fig. 5). Aluminium-selective fluorescence microscopy was successful in identifying aluminium in extracellular and intracellular locations in neurones and non-neuronal cells and across all brain tissues studied (Figs.1-5). The method only identifies aluminium as evidenced by large areas of brain tissue without any characteristic aluminium-positive fluorescence (Fig. S1).
    This is the second big mistake of this paper. If the author wants to make the claim he proposed here, then he has the obligation to show a counterstain using selective markers for neurons (e.g. MAP2, bIII-tubulin, NeuN….), astrocytes (e.g. GFAP), microglial cells (CD11b), leukocytes (CD3), macrophages (CD45), blood vessels (e.g. PECAM-1, claudin-5). This could have been easily performed (using a secondary antibody conjugated with Alexa Fluor 555 or better Alexa Fluor 647)  and would have give support to this claim.
    If the author can identify cells by the naked eye, he is either equipped with  Superman X-ray eyes or he is just imagining things.

    The discussion quickly gets into an anti-vaxxer diatribe and throws the minimal amount of scientific data under the bus.
    For example, the author throws this sentence as is: “We recorded some of the highest values for brain aluminium content ever measured in healthy or diseased tissues in these male ASD donors including values of 17.10, 18.57 and 22.11 g/g dry wt. (Table 1).” Firstly, where does it get this data? You cannot sum technical replicates, you have to average them (even with considering the huge variability between technical replicates). Secondly, how can the author make a claim like this without providing values from controls (well there are no controls) or from the literature. It is like “we have recorded the highest amount of leukocytes in ASD patients blood samples with values of 11.3, 12.0 and 11.5 x10e3 cells/mm3.” I cannot make an interpretation or conclusion without knowing the reference from the normal population (normal range 4.5-11x 10e3 cells/mm3) or from control groups. The average Al level was 2.38-4.79 microg/g tissues in male ASD and 1.15 in the female ASD patient. Such levels were very similar to those reported in samples from patients suffering from familial form of Alzheimer’s disease.
    Slide3

    The data is interesting but we are lacking additional female samples to make a claim as he did: “All 4 male donors had significantly higher concentrations of brain aluminium than the single female donor.” He lacks the proper conditions to run the statistics (you need same number of patients in male and female to make such claims) and even the important inter-individual variability makes it unlikely that he could achieve the statistical significance. This is a statement that would put a graduate student in shame for overconfidence in the data.
    Then goes the tirade “What discriminates these data from other analyses of brain aluminium in other diseases is the age of the ASD donors. Why, for example would a 15 year old boy have such a high content of aluminium in their brain tissues? There are no comparative data in the scientific literature, the closest being similarly high data for a 42 year old male with familial Alzheimer’s disease (fAD) [19].” (another Exley paper published…..in the same journal). We are dealing with the same issues (lack of controls, huge variability in the technical replicates…..).
    Now if you plot the average patient Al levels agains the age, regardless of the condition, you end up with an homogenous cloud. Now, two things have to be noted here: seems there is no impact of Al levels based on the disease (only age seems to matter between ASD and AD) and there is no correlation between increase in brain Al and age, at least in the very small sample size.
    Data 2

    No pun intended, but the data scatter looks vaguely like the United States map. Again, it shows the need of data from asymptomatic patients to estimate the burden of Al in the brain.
    Since we have not access to Al content in the brain, we have to see some values in the literature. A study by Andrasi and colleagues (https://content.iospress.com/articles/journal-of-alzheimers-disease/jad00432) provide some Al levels in control samples. According to their study, the average Al content in control samples were between 1.4 to 2.5µg/g dry tissue. We are indeed not far from the value reported by this study, especially when you consider the important standard deviation in these samples.

    Maybe it is also to consider the other study by Exler on Al level in brain samples from patients associated with familial form of Alzheimers disease (fAD) and familial dementia. In that study, all reported with Alzheimers (some with early onset, some with late onset based on age), the Al values reported were ranging from 0.34microg/g tissue (male) to 6.55microg/g (female, presenting a mutation in the PSEN1 gene, a known gene in FAD). So are we just measuring noise and try to extrapolate data from noise? Thats some bold statement that should have been smashed already by a decent reviewer in the field of neurosciences.
    But seeing these two papers went through in a apparent free ride is not looking good for the journal integrity.

  3. Conclusive Remarks
    To make a claim is one thing, to back it up with robust data is another thing. I think Exley jumped the shark a while ago and started to aluminum as the big bad wolf in every little things. But a wolf can be tamed, kept out from showing danger to the community and somehow co-exist. But for Exley, like Shaw, like Gherardi, aluminum is the devil incarnate. God forbid it has been used for 70 years and showed barely more than simple coincidence in its association with some disease, aluminum is their dead horse that worth being beaten again and again. If your funding sponsor will give you money for showing a link between aluminum and autism, lets give them what they want. Ethically it is insane, but when you need to keep your lab and your faculty position afloat, sometimes making the pact with the devil and throwing the scientific integrity and the philosophism that is given to you  following your thesis defense can be tempting. Sometimes, it feels that anti-vaccines researchers are like Faust and succumbed to the offer made by Mephistopheles offer. But this come with a price and a hefty price to pay: the loss of your integrity as a scientist.
    So my question is what is coming next to patients on the spectrum: does this study will be used to support the anti-vaccine agenda (another reason to yell “Aluminum is a chemikillz” in parenting groups?) and breakdown the herd immunity? Bogus remedies by bleach enemas and drops (the infamous CD/MMS)? or give a support to chelation therapy? gluten-free/casein-free diet? Or like Exley once claimed have these people drink ad nauseam silicon-rich water like Fiji water or Volvic water with the magic claims that the silicon with drain your brain from the Al contained inside it?
    This kind of deeply-flawed studies, lacking proper controls and driven by an ideology over the facts are dangerous because they prey on the meek and enrich modern snake oil sellers.

 

[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.

 

 

 

 

 

 

 

 

 

[Sciences/Neurosciences] International/European Society of Neurochemistry (ISN-ESN) Meeting 2017 – Paris (France). A summary

Today is the last day of the ISN-ESN biannual meeting taking place this year in Paris (France). The venue was taking place at the Palais Des Congres near Porte Maillot (right on the periphery of Paris). I thought it was a great place for the venue, first by its location (excentered from inner Paris, giving more affordable options for lodging), but also by hosting a shopping mall in the basement level (with affordable lunch options including a Galeries Gourmandes and a Paul Patisserie). Another special perk was the presence of complimentary coffee during the morning and afternoon session breaks.
The presence of vendors was fairly minimal but the welcome package provided by ISN was fairly nice. It included:

A mug of your choice (I took molecular basis of disease of course),
IMG_0547

And a set of 10 RATP tickets allowing you to wander inside Paris when the urge of sightseeing overcomes your thirst of science:
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This is a first time I am attending a ISN meeting, following the acceptance of my paper by the Journal of Neurochemistry. It is a small conference (maybe 500 attendees, this is a high estimate) but it does not mean the quality of science was small too. The conference was taking place on four full days (21-24 August) with morning plenary lectures including a senior keynote speaker and a junior keynote speaker, followed by two breakout sessions (one morning, one afternoon) covering different topics including development, gene and genetics, synapses and neurotransmission, molecular basis of diseases, neurodegeneration or cell energetics.

One of the nice thing was this huge crowd-sourced timeline in which attendees could fill it with stickers indicating their first publication in Journal of Neurochemistry, their first enrollment in one of the different societies.
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Interesting fact, the first ISN took place in Strasbourg (my hometown) in 1967 and 50 years later, one attendee was still attending the same ISN meeting! Hail to the elders!

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Senior keynote lectures were very instructive including a keynote lecture by Pr. Tamas Horvath (Yale University, USA) on the selective depletion of Agouti-gene related protein neurons and its impact on feeding behavior. These neurons are present are very few numbers (3000-6000) but play important role in feeding. The take home message? Resistance (to chocolate cake) is futile!
Another interesting keynote lecture was from Pr. Yoshi Hirabayashi (RIKEN, Japan) on glycolipids, their known impact on Gaucher’s disease and more interestingly their contribution into Parkinson’s disease. One slide to highlight the complexity of the topic is this one summarizing the different types of glycosphingolipids present in mammalian brains. Yes, this will be part of your next biochemistry quiz.

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Finally, todays senior keynote lecture by Pr. Giovanna Malluci (Cambridge University, UK) on the importance of unfolded-protein response stress and its contribution to several neurodegenerative diseases (in particular on prion diseases), with the importance of elongation factor 2E (elF2E) as a rescue pathway in neurodegeneration. More interestingly was the description in the second part of the cold-shock response and the contribution of RBM3 as a neuroprotective agent. I was aware of the importance of cold in hypoxia tolerance (drowning in frigid water decreases the gravity of brain injury inflicted by hypoxia compared to warm water) but I was always skeptical on the use of cooling blanket on stroke patients to cool their body down. It seems there is some vestigial molecular pathways initially used in evolutionary adaptation in hibernating animals that maybe still present in non-hibernating animals via RBM3. It would be interesting to see how this pathway cross-talk with the HIF-1 pathway.

Other concurrent sessions were interesting including one on transporters in the CNS (especially one on glutathione handling in astrocytes through MRPs), the importance of TDP-43 in ALS and other diseases, SIRT6 and its importance in neurodegenerative (including the possible involvement of Wnt and HIF-1 pathways), mitochondria bioenergetics and the discussion and debate on mitochondria movements in astrocytes and neurons (with even the discussion on Eng Lo’s paper on mitochondria transfer following stroke injury) or novel aspects of neural development and neurogenesis.

The poster sessions were well designed with the exception of the manned poster sessions. Poster sessions were initially scheduled between the morning and afternoon concurrent sessions but the presence of poster authors was requested only during the evening socials after 6:00PM. By principle, I am done with science by 5:00PM if I have been bathing in since the morning, so I ended up seeing a lot of “empty” posters and wished I could have a chance to chat and talk to the poster authors. I think this is were SfN poster session is more adapted: you have half-day to showcase your poster and have a time period (2 hours) to stand next your poster. Maybe the organizers could take this into account for ISN2019 taking place in Montreal.

Finally, the ISN see themselves through the Neurochemistry consortium as funny people and hell yeah they know how to bring fun with a complimentary funny photomaton booth. Another opportunity for me to let the weird and funny coming out of me 🙂

See you in probably the ASN meeting 2018 in Riverside, CA and ISN2019 in Montreal (Quebec, Canada)!

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[Neurosciences/Cancer] About Sen. McCain brain tumor……and glioblastoma multiforme

You may have heard the tragic news that broke hell under the feet of Senator McCain (R-AZ) and his family on Wednesday. According to several sources, Senator McCain biopsy taken from his recent medical examination revealed to be classified as “glioblastoma multiform” (or GBM) for short.
I am not a brain cancer specialist but I have been doing some collaboration with a research group focused on GBM and I know all too well what does it mean and what is the prognosis. This is a type of tumor I would not wish my fiercest archenemy to get. I thought it would maybe help me to make a lay summary on GBM and explain why the BBB in that case is one of our fiercest challenge for drug delivery.

1. What is glioblastoma multiforme?
Glioblastoma multiforme (aka GBM) is a primary brain tumor characterized by its heterogeneity. However, we assume that GBM is originating from tumor astrocytes. Astrocytes are an important cell type of the macroglia, outnumbering neurons from 3:1 to 5:1. For a long time, astrocytes were considered as “glue cells”, playing only a function of scaffold and nourishing cells to neurons.
However, in the last 50 years, astrocytes have been shown to play much more important roles including the induction of the blood-brain barrier phenotype, regulation of the cerebral blood flow, modulation of neuronal cell activity, ability to form a parallel signaling network and also to play an important function in terms of protection of the brain during diseases.
The World Health Organization (WHO) classify GBM as a grade IV brain tumor (https://link.springer.com/article/10.1007/s00401-016-1545-1), meaning this type of cancer is classify as highly aggressive. Because the brain is a very soft tissue, tumor cells can easily proliferate, migrate and invade the surrounding healthy tissues.
The cause of GBM remains unclear, however we know that some GBMs are evolved from other types of brain tumors that have a lesser malignancy like lower-grade astrocytomas (grade II) or anaplastic astrocytomas (grade III). GBM is considered the most common type of primary tumor (not caused by metastatic cells) but also remains pretty rare with a case of 2-3 new patients diagnosed with the condition for every 100’000 inhabitants. There is a possible sexual dimorphism, as men are more likely to be affected than women (3:2 ratio), with an increased risk with age (https://www.ncbi.nlm.nih.gov/pubmed/17373878).
There is no particular risk factor associated with GBM. So far, we assume it has a strong genetic background, as several genes have been associated with GBM including some abnormalities (including loss of DNA in a chromosome domain) on the chromosome 10, mutations in various genes including TP53 (tumor suppressor gene, its function is to repair cell DNA or to induce cell death by apoptosis if it fails to repair), MDM2 (pro-survival gene, its function is to promote cell survival), EFGR and PDGFRα (these are two receptors that induce cell growth, cell proliferation and cell survival upon stimulation by growth factors).
Also noteworthy, there has been speculation and a perpetuated myth that wireless cell phones activity are associated with an increased risk of developing brain tumors. There is no reliable studies (both on epidemiological standpoint and on animal models) that can show an association between the use of cell phones with increased risk of brain tumors.

2. What are the treatments and prognosis for patients with GBMs?

This is where I cannot have much optimism. GBM is a very aggressive type of cancer. The average survival rate is about 18 months, with less than 5% of patients making through the 5-year milestone.
Like any type of cancer, there are different options proposed: radiation therapy, surgery and chemotherapy.
Surgery is commonly practiced but have several challenges: Firstly, it is very hard to identify GBM tissue from the healthy tissue by naked eye during surgery. The neurosurgeon has to rely on the MRI cliches to resect the tumor tissue. Secondly, the neurosurgeon wants to maximize the removal of tumor tissue but also he/she wants to limit the damage to the surrounding healthy tissue to not induce further brain damage. Thirdly, GBM is prone to form glioblastoma stem cell-like cells (GSCs) that share several features with stem cells. These cells can tolerate very aggressive environment and can rapidly proliferate. This is one of the common complication occurring in GBM patients. After you remove the tumor and see no trace of it under the MRI, you conclude it got eliminated. Only to find out three months later that the tumor grew back in size and started to invade more brain tissues.
Chemotherapy arsenal for GBM is very limited. So far, temozolomide is the way to go for GBM. However, 50% of the patients will not respond to temozolomide due to a mutation in the MGMT gene capable to inactivate it (http://www.sciencedirect.com/science/article/pii/S2352304216300162). Other anti cancerous agents including EGFR inhibitors (e.g. lapatinib) fail to show any activity to the presence of a pathological form of the blood-brain barrier (BBB) called “brain-tumor barrier” (BTB). This abnormal form of the BBB involve interactions with brain tumor cells. For a long time, the scientific community thought that BBB surrounding brain tumors was leaky and therefore accessible to chemotherapeutics. However, we know that indeed there is a BTB that can act as a barrier for the penetration and delivery of drugs into the tumor region.

There are some new avenues and approaches to target GBM but they are still very experimental. Amongst them, the possibility to use oncolytic viruses like a modified form of the polio virus capable to set brain tumor cells into “auto-destruction” mode. The second avenue explored is possible use of immunotherapy. The rationale behind is to help the immune system “to learn” about the tumor cells as foreign agents and strike them. There are some success using antibodies targeting tumors and also by reprogramming patients own cells (CAR-T cell therapy).

The diagnosis of GBM is probably one of the most difficult one a neurologist or neurosurgeon has to set, as it has a very poor prognosis. Let’s be honest, it is not looking good and for someone like Senator McCain that has been facing death several times during his military duties this is probably the toughest one to overcome.

3. Concluding remarks

This is why we need to foster research in brain tumors, this is why we need funding to help research findings, this is why we need clinical trials to pick the most promising drug candidate to fight this type of cancer, this is why we need to have a public health policy that ensure healthcare coverage for everyone can have access to treatment to beat the odds and not have to decline treatment because of the huge costs associated that health insurance may simply refuse to share the burden.

I am so embarrassed to say that right now the only thing we can provide Senator McCain and anyone with GBM and their relatives are our sympathies and our wishful thinking. This is why I have colleagues, peers working days and nights, weekends to bring on a “silver bullet” capable to annihilate such condition.

If you are looking to help, the best I can advise is to support research by donating to association like ABTA (http://www.abta.org) that focuses on funding research on brain tumors. Also considerate to let your voice heard and support healthcare policies that ensure an universal coverage of the population regardless of their age, gender, socio-economic status. Because refusing treatment by fear of letting your most loved ones with a humongous amount of debt should be the last of your worry.

 

 

 

 

 

 

[Sciences/BBB] Endothelial TLR4 and the microbiome drive cerebral cavernous malformations (Tang et al., Nature 2017)

You may have heard about this study that showed how your gut bacteria were responsible for stroke. Of course headline news always love to stretch scientific findings as much as I use to stretch my Stretch Armstrong when I was a kid. However, the paper cited was indeed published in Nature and can be found here:
https://www.nature.com/nature/journal/vaop/ncurrent/full/nature22075.html

It is a very interesting paper to read, because a lot of it sounds like a serendipity and lucky strikes. This paper investigated changes in two mouse models of cerebral cavernoma (Ccms). Ccms are a particular type of hemorrhagic stroke because they are mostly genetics (there are three Ccm genes described, in this study they focused on Krit1 and Ccm2) and most of the time go unnoticed. Mutations in those genes result in some alterations in brain microvessels, making some tiny anatomical abnormalities resulting in a higher susceptibility in some of these micro vessels to spontaneously burst and bleed.

The authors of this study have been developing Cre/Lox mice colonies for Ccm2 and Krit1 to better understand the pathology of this disease. The advantage of Cre/Lox is you can knockout a gene in a specific place at a specific time, just by injecting or providing a molecule (usually tamoxifen) that will induce it.

They have been breeding mice that were deficient in Ccm2 or Krit1 and were as expected developing brain micro bleeds (usually around their first two weeks of postnatal age). Following some changes in the animal facility, they observed that a small fraction of their mice colonies suddenly became resistant to cerebral micro bleeds: they still carried the mutations but they fail to develop these microbleeds. Therefore some non-genetic factors were influencing this resistance pattern.
Things became even more interesting as they found that among some of these resistant mice, some developed again the microbleeds within a same littler. The only difference between those developing the microbleeds and those which did not were apparently related to the intraperitoneal (i.p.) injection of tamoxifen. Have the authors provided the tamoxifen through the drinking water, that would have ended the story here.
The authors indeed found that those who reversed their phenotype from resistant to susceptible developed a bacterial infection at the site of the i.p. injection suggesting that such micro bleed was driven by some bacterial factor. They showed that similar results were obtained if they injected LPS (a common Gram-negative antigen) to these mice.

They identified two receptors known to play a role in cellular response to pathogens (we refer such signaling pathways as Pathogen Associated Molecular Patterns or PAMPs): TLR4 (toll-like receptor 4) and CD14 (TLR4 co-receptor). By knocking down these receptors in their Ccm-resistant animals, they were capable to block such bacteria-induced response. The possible interactions of Gram-negative bacteria with these two receptors at the blood-brain barrier maybe enough to trigger the cerebral micro bleeds.

What is also interesting is that mutations in these two genes (some single nucleotide polymorphism or SNP) in patients known to have an history of Ccm also resulted in a higher probability to have brain microbleeds.

I will not spoil the rest of the story but it confirms the presence of a brain-gut axis in Ccm, suggesting the possible effect of the gut microbiota as a risk factor to increased microbleeds in Ccm patients. Let it be clear, these bacteria WILL NOT induce Ccm in normal invididuals. It increase the risk of bleeds in patients already at risk of Ccm.

Another limitation is that in vitro data to confirm the presence of TLR4/CD14 at the BBB and fails to explain how these receptors are triggered by the gut microbiota. The authors suggested a bacteremia (circulating bacteria from gut to the brain via bloodstream) but I remain skeptical about it.

Nevertheless it is a very good paper that worth being read.

 

[Science/Neurosciences] Mole rats running on…..fructose!

You may have heard about this paper from Park TJ and colleagues (Park TJ et al., Science 2017) on how mole rats were showing extreme compliance to anoxic (0% oxygen) level, no? It made the news these last couple of weeks and finally was able to put my hand on. You can access to it here (need to have a Science subscription though) but I read it and it is really interesting for many reasons, especially because I try to think how can we translate it as a therapeutical strategies for hypoxemic pre-terms babies or even as a stroke fighting-drug.

First, mole rats. Oh mole rats! Not the prettiest mammals out there. They are naked, they have long teeth and look all wrinkled. But they are underground dwelling animals like moles. Underneath, oxygenation is scarce and these animals have developed formidable adaption to hypoxia. We as humans can barely survive 8% oxygen (thats about the Mount Everest). At 6% oxygen (thats what would happen if a aircraft cabin undergo a depressurization), you die within minutes.

In this experiment, they went fairly extreme, they put the animals into anoxia (0% O2) and looked how long the animals would survive. They used a common mouse strain as a control. Mice rapidly died at 100% rate at 5% O2 and died twice faster (based on the number of breaths) at 0% O2. In opposite, mole rats went 30 times longer than mice and still were doing fine (0% deaths). Were mice died within 60 seconds, molerats died over 1000 seconds of anoxia. One possible reason is their ability of their heart to beat much longer than mice.

Now what is interesting is how the authors came to fructose. Mammalian cells run on glucose through the following biochemical pathway (see below):

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I will spare you the Krebs cycle but this is what every since healthcare and life scientist have to learn. Glucose is broken down into many intermediates and at the end becomes pyruvate. From pyruvate, you can enter the Krebs Cycle and produce a significant amount of ATP (the fuel cell of every living organism) needed to provide energy for any biological process. Krebs cycle is very good at it and provides an ATP yield of 36ATP/glucose consumed. However, the Krebs cycle stall under hypoxia and forces the cell to adapt. In particular, it needs to regenerate NAD+ (from NADH) in order to keep the system flowing and producing energy. One way mammalian cells solved it is by converting pyruvate into lactate. Thats allow cells to produce some energy (2ATP/glucose) and regenerate its NAD+. However lactate has tendency to accumulate and develop adverse effect (the famous muscle cramps any runners have experienced).

Fructose is not much different from glucose, it has the same composition but just a little difference in the molecular structure.  We get fructose from our daily diet made of fruits and vegetables, but also from refined sugar (sucrose or HFCS, same deal).

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Now fructose can bypass and feed the glycolysis at different steps:
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Fructose can produce glyceraldehyde-3-P (GA3P) and dihydroxyacetone-P (DHAP) and enter the rest of the glycolysis. Now like glucose, fructose needs a transporter to enter inside the cells. Glucose has a myriad of glucose transporters (GLUTs and SGLTs) that can provide glucose inside the cells. But not fructose. These transporters have very poor affinity for fructose. In that case, fructose has one transporter called GLUT5 that prefers fructose over glucose.
Now this is where it becomes interesting, mole rats show much higher levels of fructose than mice during anoxia in many organs and in blood. Now the interesting fact is the high prevalence of it as fructose-1-P in the brain, only this form. How it goes in? I don’t know but mole rat brains have a higher GLUT5 expression than mice. Where this transporter is expressed? I don’t know either but it would interesting to look at this transporter at the BBB.

What is interesting is the difference in how mole rats  brain and heart differ from mice in terms of fructose activity. When administered fructose over glucose, mole rats organs know to switch between the two sugars to gets its energy. In the other hand, mice organs fail to switch and result in decrease their activity.

Now the question I have (since I am working on glucose transport across the BBB and its impact in kids suffering from GLUT1 deficiency) is: does human express GLUT5? If yes, which brain cells express it and if these cells can adopt fructose as a source of energy?