011615 microbiota Flashcards
mucins’ role in host defense
binds some commensals
bacterial exclusion
containment of secreted antibodies and antimicrobials
paneth cell AMPs-give ex
defensins
lysozyme
phospholipase A2
RegIIIgamma
predominant immunoglobulin secreted as a defense in the mucosal areas
IgA
how is mucosal IgA inducted?
1st way: bacteria is engulfed by dendritic cell. DC goes to mesenteric lymph node to induce B cell activation. get plasma cell secretion of IgAs
2nd way: M cell encounters bacteria. then activatres B cells in Peyer’s patches
activities of IgA
surrounds microbe and repels attachment to mucosal surface
mucus trapping-may associate with mucins and trap microbes in mucus blanket
virus neutralization
etc
if you lack a good immune system, what happens?
commensal microbiota can invade
healthy microbiota contains what
balancec omposition of three major classes of bacteria:
symbionts, commensals, pathobionts (live as commensals but have potential to induce pathology)
microbial composition is determined by
site in GI
O2 tension
innate immune factors
host nutrition/diet
role of intestinal microbiome
protective against pathogens
induce immune system development
metabolic fxns
fxn of short chain fatty acids
commensal bacteria ferment nondigestable dietary polysaccharides to produce short chain fatty acids
SCFAs regulate PMNs, DCs, macrophages, epithelial cells. SCFAs regulate expression of virulence factors on bacterial pathogens so that they are not so toxic
abnormalities in composition of microbiome can result in increased risk of autoimmune, allergic, infectious and metabolic diseases: true or false
true