Gut Bacteria and Neurological Disorders: Uncovering the Exact Mechanism

On an ordinary day, one of my posts on Facebook may reach 200 people.  A couple of weeks ago though, I noticed that one reached well over 1000.  It was regarding recent research out of Harvard, published in the journal, Nature, about the role of gut bacteria in multiple sclerosis.[i]

My original post was of Forbes Magazine’s coverage[ii], but after reading another article about it in Parkinson’s News Today[iii], I decided it was worth a blog post to make sure everyone is aware of it and understands it.  It really is HUGE news.

To summarize then:

There are several kinds of cells in the brain but the two that are of interest here are the microglia, which are the immune cells of the brain (also responsible for clearing out cellular detritus, plaques (such as are found in Alzheimer’s) and dead neurons (nerve cells) – and astrocytes, which do various things including forming the blood-brain barrier and responding to injury. Damaged astrocytes are believed to contribute to neurological diseases like Parkinson’s and MS.

While certain byproducts of the gut bacteria are known to promote inflammation, these scientists wanted to study how some of these might also act directly on the microglia to prevent inflammation.  They discovered that the microglia in the brain release two proteins to regulate the astrocytes and subsequent disease development:  TGF-alpha, which limits the detrimental effects from astrocytes, and VEGF-B, which promotes it. Using donated brain tissue from dead MS patients, they proved that these two proteins are associated with the lesions found in MS patients.

The scientists found the gut bacteria’s metabolites, formed from the breakdown of the amino acid, tryptophan, cross the blood-brain barrier and directly affect the microglia, reducing brain inflammation.  Using a mouse model, they found that TGF-binds to receptors on the astrocytes and stops them producing inflammation.  (VEGF-B does the opposite, and causes worsening of the MS-like syndrome researchers use in rodents to study MS.)

From the paper’s abstract: “…these findings define a pathway through which microbial metabolites limit pathogenic activities of microglia and astrocytes, and suppress CNS inflammation. This pathway may guide new therapies for multiple sclerosis and other neurological disorders.”  What other neurological disorders?  Besides MS and Parkinson’s, there’s Alzheimer’s, the almost-always-fatal-brain-cancer, glioblastoma, the-almost-always-rapidly-fatal ALS…and then of course, there are other neurological illnesses associated with activation of the microglia, like autism.

As I said – HUGE news.

The researchers state emphatically that it’s too soon to make specific probiotic or dietary recommendations to patients.  Then again, they also say they are “…in the process of securing intellectual property agreements and also developing potential probiotic supplements with pharma companies…”

With yet another friend recently receiving a terrible diagnosis (this time, ALS), I really, really hope this research morphs into treatments soon.


[i] Rothhammer, V, et. al. Microglial control of astrocytes in response to microbial metabolites.  Nature. 2018. doi:10.1038/s41586-018-0119-x



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