The gut bacteria affect the brain’s blood vessels

I’m obsessing on some research[i] I read about last week.

 “A study in mice and humans suggests that bacteria in the gut can influence the structure of the brain’s blood vessels, and may be responsible for producing malformations that can lead to stroke or epilepsy.  The research…adds to an emerging picture that connects intestinal microbes and disorders of the nervous system.”

Scientists from the University of Pennsylvania, who were studying cerebral cavernous malformations (CCMs – which are clusters of dilated, thin-walled blood vessels that can cause blood to leak into the surrounding brain tissue causing strokes and seizures), noticed that when gut bacteria were eliminated, the number of lesions was greatly lessened.

The researchers observed that the mice with gut abscesses that contained a certain kind of bacteria had far more lesions in the brain.  These gram-negative bacteria produce a molecule called lipopolysaccharides (LPS) that actives the immune system.  (Remember my post on the metabolome? – the metabolites produced by your gut bacteria?)  When the scientists injected mice genetically susceptible to CCMs with LPS they developed markedly more lesions.  When they removed the receptors (TLR4) to LPS the mice no longer formed lesions.  That is – the metabolites of the gut bacteria were the variable factor that led to the same genetic fragility having a greater or lesser negative impact.


The first thought that went through my head when I read this:  “It is estimated that up to 80% of children with autism may experience seizures.  We know that the gut bacteria is altered in autism.  Is this research relevant?”  I have no idea…but the idea is certainly intriguing.

Apparently there is a drug already being tested that blocks TLR4 and these scientists are now hoping to study humans with the genetic mutations which can cause CCM.  The same mutation can lead to vastly different outcomes in people, after all.  Is this the result of variability in their microbiomes?  And – can improving the quality of the microbiome improve the quality of the brain’s vasculature?



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