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Induction of immune responses by intestinal segmented filamentous bacteria
Pacáková, Iva ; Dobeš, Jan (advisor) ; Schwarzer, Martin (referee)
The intestine is constantly exposed to a variety of pathogens, and therefore a proper function of the intestinal barrier is essential for the overall health of the body. Segmented filamentous bacteria are members of the gut microbiota residing in the terminal ileum of the small intestine, where they penetrate through the mucus layer and tightly associate with intestinal epithelial cells. This SFB association with the epithelium is accompanied by the formation of endocytic vesicles filled with an antigen that triggers the IgA production in the intestine and the Th17 cell dependent immune response. There are two steps for the induction of Th17 cells. First, SFB-dependent induction of Th17 cells requires antigen presentation by MHC class II molecules. Therefore, antigen-presenting cells migrate to the site of induction in mesenteric lymph nodes and prime antigen-specific naive T cells to become RORγt+ pre-Th17 T cells. Secondly, activated T cells migrate back to the lamina propria, where they undergo functional maturation by triggering cytokine production. As a result, Th17 cells accumulate in lamina propria, where they produce their effector cytokines IL-17 and IL-22, further affecting the gut's overall balance. However, the extensive Th17 polarization induced by SFB may subsequently contribute to...
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