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BackgroundThe recently identified member of the TNF superfamily TL1A (TNFSF15) increases IFN-gamma production by T cells in peripheral and mucosal CCR9+ T cells. TL1A and its receptor DR3 are up-regulated during chronic intestinal inflammation in ulcerative colitis and Crohn's disease (CD). TL1A gene haplotypes increase CD susceptibility in Japanese, European, and US cohorts.Methodology and principal findingsHere we report that the presence of TL1A gene haplotype B increases risk in Jewish CD patients with antibody titers for the E. coli outer membrane porin C (OmpC+) (Haplotype B frequency in Jewish CD patients: 24.9% for OmpC negative and 41.9% for OmpC positive patients, respectively, P< or =0.001). CD14+ monocytes isolated from Jewish OmpC+ patients homozygous for TL1A gene haplotype B express higher levels of TL1A in response to FcgammaR stimulation, a known inducing pathway of TL1A, as measured by ELISA. Furthermore, the membrane expression of TL1A is increased on peripheral monocytes from Jewish but not non-Jewish CD patients with the risk haplotype.Conclusions and significanceThese findings suggest that TL1A gene variation exacerbates induction of TL1A in response to FcgammaR stimulation in Jewish CD patients and this may lead to chronic intestinal inflammation via overwhelming T cell responses. Thus, TL1A may provide an important target for therapeutic intervention in this subgroup of IBD patients.

Abstract: FOXP3+CD4+ regulatory T cells (TR) have emerged as important regulators of immune responses. The aim of our study was to assess the frequency and functional characteristics of FOXP3+CD4+ TR in Crohn’s disease (CD). We report that FOXP3+CD4+ TR cells are expanded in mucosal lymphoid tissues (lamina propria and MLN) but are decreased in the PB in active CD. Patients treated with thiopurines, but not steroids or anti-TNF-α inhibitors, have a lower frequency of PB FOXP3+CD4+ TR (7.8±2.4% vs. 9.9±1.8%, p =0.01). FOXP3+ cells were localized in the lamina propria (LP), muscularis mucosa and serosa and accumulated in granulomas, whereas in MLN they localize in the T cell rich areas. MLN CD4+CD25+ T cells from both CD and normal intestine efficiently suppress the proliferation of effector CD4+CD25− T cells. T cell activation of MLN in vitro with anti-CD3 plus anti-CD28 Abs enhances the expression of FOXP3, both at the protein and transcriptional level, which is further enhanced by the addition of TGF-β. In summary, there is an expansion of FOXP3+CD4+ TR cells in mucosal lymphoid tissues in CD; they accumulate in areas of active inflammation, including granulomas and retain potent regulatory activity ex vivo. [Copyright &y& Elsevier]

TL1A contributes to the pathogenesis of several chronic inflammatory diseases, including those of the bowel by enhancing T H 1, T H 17, and T H 2 responses. TL1A mediates a strong costimulation of these T H subsets, particularly of mucosal CCR9 + T cells. However, the signaling pathways that TL1A induces in different T H subsets are incompletely understood. We investigated the function of TL1A on human T H 17 cells. TL1A, together with TGF-β, IL-6, and IL-23, enhanced the secretion of IL-17 and IFN-γ from human CD4 + memory T cells. TL1A induced expression of the transcription factors BATF and T-bet that correlated with the secretion of IL-17 and IFN-γ. In contrast, TL1A alone induced high levels of IL-22 in memory CD4 + T cells and committed T H 17 cells. However, TL1A did not enhance expression of IL-17A in T H 17 cells. Expression of the transcription factor aryl hydrocarbon receptor, which regulates the expression of IL-22 was not affected by TL1A. Transcriptome analysis of T H 17 cells revealed increased expression of IL-9 in response to TL1A. Blocking IL-9 receptor antibodies abrogated TL1A-induced IL-22 secretion. Furthermore, TL1A increased IL-9 production by peripheral T H 17 cells isolated from patients with Crohn's disease. These data suggest that TL1A differentially induces expression of T H 17 effector cytokines IL-17, -9, and -22 and provides a potential target for therapeutic intervention in T H 17-driven chronic inflammatory diseases., (© Society for Leukocyte Biology.)

Background: CD4+CD25+ regulatory T cells (TR) can prevent or treat experimental murine colitis but little is known about their potential role in human inflammatory bowel disease (IBD). FOXP3 is a transcription factor that plays a critical role in the development and function of CD4+CD25+ TR. The aim of this study was to examine the presence and functional characteristics of TR cells in colonic lymphoid tissues in patients with ulcerative colitis (UC)., Methods: FOXP3 expression was assessed by flow cytometry, immunohistochemistry, and reverse-transcriptase polymerase chain reaction (RT-PCR). Functional characterization of CD4+CD25+ cells was analyzed by suppression of proliferation and secretion of cytokines by cocultured effector CD4+CD25- T cells., Results: FOXP3 +CD4+ T cells are increased in the lamina propria (LP) of inflamed and noninflamed areas of UC colon compared to normal colon. CD4+CD25+ T cells in UC mesenteric lymph nodes (MLN) express FOXP3 mRNA and protein and suppress the proliferation of autologous MLN CD4+CD25 T cells. The suppressor activity of MLN CD4+CD25+ T cells is cell contact-dependent but cytokine-independent. In addition, CD4+CD25+ T cells potently suppress the production of both Thl (IFN-gamma, IL-2) and Th2 (IL-5, IL-13) cytokines by cocultured CD4+CD25 T cells. FOXP3' cells localized in the T-cell-rich areas of MLN and occasionally present in the follicles., Conclusions: There is an expansion of FOXP3+CD4+ T cells in mucosal lymphoid tissues in UC. CD4+CD25+ isolated from UC MLN express FOXP3 and display features of TR cells in spite of active mucosal inflammation. These data suggest that their suppressor activity may be abrogated in vivo or they are unable to counterbalance the chronic mucosal inflammation in UC.