Immunoregulation by the gut commensal bacteria or probiotics

大量的共生细菌在哺乳动物的胃肠道中定居。这些生物在诱导肠道免疫系统的发育和维持体内平衡方面起着关键作用。在这项研究中，我们揭示了类杆菌促进盲肠生发中心的发育，并通过增加IgA和B细胞来诱导大肠中总IgA的产生。此外，我们还利用无菌小鼠，证明肠道共生菌通过调节肠道和全身T细胞表型，促进T细胞低反应性，并下调饮食抗原诱导的血清抗体反应。

Huge numbers of commensal bacteria colonize the gastrointestinal tract of mammals. These organisms play a key role in inducing the development and maintaining the homeostasis of the intestinal immune system. In this study, we have revealed that Bacteroides promote the development of the germinal center in the cecum, and induce total IgA production in the large intestine by increasing IgA^+B cells. Furthermore, we have demonstrated that intestinal commensal bacteria promote T cell hyporesponsiveness and down-regulate serum antibody responses induced by dietary antigens through modulation of the intestinal and systemic T cell phenotype by using germ-free mice.