En presenting cell activation in RELM-/- mice, we examined if neighborhood CD4+ T cell proliferation and activation was altered. Ki67 staining of mLN CD4+ T cells revealed infection-induced increases in the frequency of Ki67+ CD4+ T cells from WT mice that had been lowered in RELM-/- mice (Fig. 4D). Additionally, the delta imply fluorescent intensity of Ki67 expression was significantly reduced within the infected RELM-/- mice when compared with infected WT mice, suggesting that there have been proliferative defects on a per cell basis (Fig. 4E). Associated with decreased CD4+ T cell proliferation, the frequency of activated CD44hiCD4+ T cells isolated from the colons was drastically reduced in infected RELM-/- mice in comparison to infected WT mice (Fig. 4F). Provided that RELM-/- mice exhibited a particular defect in Th17 cell activation following DSS-induced colitis (Fig. S1), we next examined Citrobacter-specific Th17 cell responses in infected WT or RELM-/- mice. Cells have been isolated in the mLN and re-stimulated with Citrobacter antigen for 48 hours and assessed for IL-17A production by intracellular cytokine staining. WT mice exhibited a robust population enhance of infection-induced CD4+ IL-17A+ T cells (Fig. 4G, H). In contrast, infected RELM-/- mice exhibited decreased frequencies of IL-17A generating CD4+ T cells in comparison with infected WT mice (Fig. 4G, H). Moreover, CD4+ T cell-derived IL-17F and IL-22 but not IFN- had been also decreased in Citrobacter antigen-stimulated mLN cells from infected RELM-/- mice (Fig. 4I). Offered the reduced proliferative capacity in the RELM CD4+ T cells, these data recommend that following Citrobacter antigen stimulation, the proliferating CD4+ T cells in RELM-/- mice preferentially express IFN. Collectively, these information recognize an immunostimulatory function for RELM in promoting bacterial infection-induced intestinal macrophage and Th17 cell activation. Given that immunity to Citrobacter is dependent on macrophage activation and on Th17 cells (20, 31), we hypothesized that the reduced Citrobacter-specific immune cell response in RELM-/- mice may perhaps lead to improved Citrobacter burden. Although there was a modest delay in Citrobacter MMP-19 Proteins site elimination in RELM-/- mice at day 14 post-infection (Fig. 4J), we observed no DENV E Proteins medchemexpress considerable variations inside the kinetics of Citrobacter colonization and clearance between WT or RELM-/- mice, suggesting that within the context of enteric bacterial infection, the immunostimulatory effects of RELM contribute to inflammatory pathology as an alternative to a vital host-protective function. Recombinant RELM treatment induces Citrobacter-induced colitis To ascertain whether or not the dampened intestinal inflammation seen in RELM-/- mice may be restored by exogenous administration of recombinant RELM, Citrobacter-infectedNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Immunol. Author manuscript; obtainable in PMC 2014 March 01.Osborne et al.PageRELM-/- mice have been injected intraperitoneally with PBS or recombinant RELM throughout infection. Regardless of high concentrations of administered recombinant RELM, rRELM-treated mice had considerably decrease RELM levels than WT mice (Fig. 5A, evaluate to Fig. 1F). Having said that, histologic examination of H E-stained colon tissue sections from PBS and RELM-treated mice revealed exacerbated Citrobacter-induced intestinal lesions following RELM remedy characterized by elevated crypt hyperplasia, submucosal edema (Fig. 5B, arrow), and leukocyte infiltration (Fig. 5B, box) relative to PBS treated m.