This indicates a fundamentally different innate response to infection between WT and MMP-9−/− mice which may contribute to an atypical fecal microbiome in MMP-9−/− mice. Recent evidence also indicates that MMPs regulate the intercellular expression of several key mediators of cell-cell binding including claudin-5 and occludin [30]. For instance, in the context

of lung injury, the pore-forming cytotoxin α-hemolysin from Staphylococcus aureus upregulates the zinc-dependent metalloprotease ADAM10, resulting in cleavage of E-cadherin and disruption of intercellular tight junctions [31]. Most MMPs are secreted factors, but many of the proteases localize to cell surfaces where they associate with and regulate a variety of adhesion molecules, such as CD44 and β-integrins [32, 33]. This indicates that MMPs could alter the binding efficiency of intestinal bacteria to Survivin inhibitor host colonocytes, thereby altering the pathobiology of an infectious colitis. MMP-7 also affects gut microbe homeostasis through cleavage of reduced cyptdin-4 (r-Crp4), a mouse Paneth cell-derived selleck α-defensin. In an in vitro model, cleavage of the peptide resulted in increased survival of Salmonella enterica serovar Typhimurium, E. coli ML35, Staphylococcus aureus, Bifidobacterium

bifidum, Bifidobacterium longum, Lactobacillus casei Bacteroides thetaiotaomicron, and Bacteroides vulgatus relative to undigested r-Crp4 [34]. Therefore, the Edoxaban presence of MMPs in the colonic mucosa can mediate physiological parameters that impact on both gut homeostasis and host-microbe interactions. Disruption of these interactions

leads to an altered microbial ecology and disease [35]. Segmented filamentous bacteria (SFB) “”Arthromitus immunis” [36]; provides mucosal protection against C. rodentium infection, as well as mediates the production of the proinflammatory cytokines IL-17 and IL-22 [23]. In the present study, qPCR analysis of the fecal microbiome revealed a larger population of SFB and higher mRNA levels of IL-17 in MMP-9−/− mice compared to WT controls, even under baseline conditions. “A. immunis” inhibits colonization of rabbit enteropathogenic Escherichia coli O103 and protects against subsequent disease development [37]. In this study, electropherograms showed that C. rodentium became a dominant component of the detectable microbiota in WT, but not MMP-9−/− mice. As noted by others [37], this study shows that the presence of SFB may provide protection against C. rodentium colonization, although our results demonstrate that commensal SFB does not offer full protection against C. rodentium-induced colitis in C57BL/6 J mice. This observation emphasizes that a shift in the bacterial population does not have an all-or-none effect; rather, it produces a graded series of responses. In previous studies, infection of C57BL/6 J mice with C. rodentium reduced fecal microbial diversity and evenness due to the dominance of C.