Development of enteric protection and immune system Gut flora

microfold cells transfer antigens (ag) lumen of gut gut-associated lymphoid tissue (galt) via transcytosis , present them different innate , adaptive immune cells.

in humans, gut flora similar adult s formed within 1 2 years of birth. gut flora gets established, lining of intestines – intestinal epithelium , intestinal mucosal barrier secretes – develop well, in way tolerant to, , supportive of, commensurate microorganisms extent , provides barrier pathogenic ones. specifically, goblet cells produce mucosa proliferate, , mucosa layer thickens, providing outside mucosal layer in friendly microorganisms can anchor , feed, , inner layer these organisms cannot penetrate. additionally, development of gut-associated lymphoid tissue (galt), forms part of intestinal epithelium , detects , reacts pathogens, appears , develops during time gut flora develops , established. galt develops tolerant gut flora species, not other microorganisms. galt becomes tolerant food infant exposed, digestive products of food, , gut flora s metabolites produced food.

the human immune system creates cytokines can drive immune system produce inflammation in order protect itself, , can tamp down immune response maintain homeostasis , allow healing after insult or injury. different bacterial species appear in gut flora have been shown able drive immune system create cytokines selectively; example bacteroides fragilis , clostridia species appear drive anti-inflammatory response, while segmented filamentous bacteria drive production of inflammatory cytokines. gut flora can regulate production of antibodies immune system. 1 function of regulation cause b cells class switch iga. in cases b cells need activation t helper cells induce class switching; however, in pathway, gut flora cause nf-kb signaling intestinal epithelial cells results in further signaling molecules being secreted. these signaling molecules interact b cells induce class switching iga. iga important type of antibody used in mucosal environments gut. has been shown iga can diversify gut community , helps in getting rid of bacteria cause inflammatory responses. ultimately, iga maintains healthy environment between host , gut bacteria. these cytokines , antibodies can have effects outside gut, in lungs , other tissues.

the immune system can altered due gut bacteria s ability produce metabolites (molecules formed metabolism) can effect cells in immune system. example short chain fatty acids (scfa) can produced gut bacteria through fermentation. scfas stimulate rapid increase in production of innate immune cells neutrophils, basophils , eosinophils. these cells part of innate immune system try limit spread of infection.