Microbial communities reside in healthy tissues but are often disrupted during disease. Bacterial genomes and proteins are detected in brains from humans, nonhuman primates, rodents and other species in the absence of neurological disease. We investigated the composition and abundance of microbiota in frozen and fixed autopsied brain samples from patients with multiple sclerosis (MS) and age- and sex-matched nonMS patients as controls, using neuropathological, molecular and bioinformatics tools. 16s rRNA sequencing revealed Proteobacteria to be the dominant phylum with restricted diversity in cerebral white matter (WM) from MS compared to nonMS patients. Both clinical groups displayed 1,200-1,400 bacterial genomes/cm3 and low bacterial rRNA:rDNA ratios in WM. RNAseq analyses showed a predominance of Proteobacteria in progressive MS patients’ WM, associated with increased inflammatory gene expression, relative to a broader range of bacterial phyla in relapsing-remitting MS patients’ WM. Although bacterial peptidoglycan (PGN) and RNA polymerase beta subunit immunoreactivities were observed in all patients, PGN immunodetection was correlated with demyelination and neuroinflammation in MS brains. Principal component analysis revealed that demyelination, PGN and inflammatory gene expression accounted for 86% of the observed variance. Thus, inflammatory demyelination is linked to an organ-specific dysbiosis in MS that could contribute to underlying disease mechanisms.
First we have gut microbes affecting the immune response and now in this paper it is telling us it is brain bacteria is the problem.
They find Bacterial Peptidoglycan (bacterial molecule) in the brains of pwMS detected in non MS and MS. That it is present in EAE and MS says to me it can’t be important. Can it? They say “ total PGN abundance per brain section was similar in MS and nonMS brains suggesting that overall bacterial burden did not distinguish MS from nonMS patients”.
Then we get the correlations and it is in MRI territory with weak weak weak correlations that means it does not tell us much.
Have a read, I’m off to get some anti-biotics:-(