Sarkis Mazmanian

Anouther talk on IBD. Inflammatory bowel disease results from a loss of tolerance to flora. Its autoimmunity due to an over active immune system.Bacteroides fragilis is a commensal that has a unique inducible effect on foxp3+ regalatory tcells. These t cells suppress inflammatory t cells.

Polysaccharide A, PSA, is an immunomolecular molecule produced by b. Fragilis mediates conversion of t cells into foxp3+ cells that produce interleukin-10. PSA is not only preventative, but curative in experimental colitis animal models. Additionally intestinal disease may result from breakdown of mucosal tolerance

‘Pathobionts’
Eg helicobacteria hepaticus.

B fragilis prevents pro inflamatory immune response in gut to maintain homeostasis.

Type 4 secretion system is a canditate for how h.h may be inducing immune response. Not all h.h. Have type 4, so looking just at 16s to see presence of species may be misleading. H.h actually invades intestinal epithemal cells, but wt had a very static colonization. Mutants of type 6 ss over colonized.Removing the pathogenicty island actually stops over colonization so its not a virulence factor? Validated in vivo

Type 6 ss. Balances host colonization and immune response. Overgrowth of pathobiomes leads to disease,  during health beneficial commensals suppress host immune response

Question pointed out that b. Fragilis is considered pathogenic itself. Its usually isolated from absecces but the presenter argued that absecces shouldnt be considered pathogenic but as protective of bact.

Ghetto laptop died so im back to typing on my phone. Back to roots!

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