Molecular analysis of commensal host-microbial relations hips in the intestine

Human beings contain complex societies of indigenous microbes, yet little i s known about how resident bacteria shape our physiology. We colonized germ free mice with Bacteroides thetaiotaomicron, a prominent component of the n ormal mouse and human intestinal microflora. Global intestinal transcriptio nal responses to colonization were observed with DNA microarrays, and the c ellular origins of selected responses were established by laser-capture mic rodissection. The results reveal that this commensal bacterium modulates ex pression of genes involved in several important intestinal functions, inclu ding nutrient absorption, mucosal barrier fortification, xenobiotic metabol ism, angiogenesis, and postnatal intestinal maturation. These findings prov ide perspectives about the essential nature of the interactions between res ident microorganisms and their hosts.