Selected commensals educate the intestinal vascular and immune system for immunocompetence

BACKGROUND: The intestinal microbiota fundamentally guides the development of a normal intestinal physiology, the education, and functioning of the mucosal immune system. The Citrobacter rodentium-carrier model in germ-free (GF) mice is suitable to study the influence of selected microbes on an otherwise blunted immune response in the absence of intestinal commensals. RESULTS: Here, we describe that colonization of adult carrier mice with 14 selected commensal microbes (OMM(12) + MC(2)) was sufficient to reestablish the host immune response to enteric pathogens; this conversion was facilitated by maturation and activation of the intestinal blood vessel system and the step- and timewise stimulation of innate and adaptive immunity. While the immature colon of C. rodentium-infected GF mice did not allow sufficient extravasation of neutrophils into the gut lumen, colonization with OMM(12) + MC(2) commensals initiated the expansion and activation of the visceral vascular system enabling granulocyte transmigration into the gut lumen for effective pathogen elimination. CONCLUSIONS: Consortium modeling revealed that the addition of two facultative anaerobes to the OMM(12) community was essential to further progress the intestinal development. Moreover, this study demonstrates the therapeutic value of a defined consortium to promote intestinal maturation and immunity even in adult organisms. Video Abstract.

• Romero, R.
• Zarzycka, A.
• Preussner, M.
• Fischer, F.
• Hain, T.
• Herrmann, J. P.
• Roth, K.
• Keber, C. U.
• Suryamohan, K.
• Raifer, H.
• Luu, M.
• Leister, H.
• Bertrams, W.
• Klein, M.
• Shams-Eldin, H.
• Jacob, R.
• Mollenkopf, H. J.
• Rajalingam, K.
• Visekruna, A.
• Steinhoff, U.