Studies on the morphological and immunological responses in the gut mucosa during the colonization of enteric microflora into germfree mice

摘要

Gut flora plays a key role in the maturation ofintestinal mucosal immune systems such as theexpression of class II MHC antigens on intestinalepithelial cells, and the cell expansion and functional maturation of both IgA-producing B lymphocytes in the lamina propria and T cell receptor (TCR) alpha beta-expressing intraepithelial lymphocytes in the intestinal epithelium in mice. Innormal mice, the mucosal immune responsesevoked through colonization of gut floraattained levels found in mice reared undernormal gut flora-bearing conditions. However,in SAMPl/Yit mice, recently established as amurine model of Crohn's disease, transmural ileitis arid cecetis developed following the introduction of commensal gut flora from normalmice, although no intestinal inflammation wasobserved under in germfree conditions. Theseresults suggested that commensal gut flora playcritical roles in the development of Crohn's disease-like intestinal inflammation in SAMPl/Yitmice. In this study, I focus on the specific interactions between the gut flora and mucosalimmune systems that induce physiological- orunphysiological mucosal immune responses.