ABSTRACT
The tumor necrosis factor (TNF)-family cytokine TL1A (TNFSF15) costimulates T cells through its receptor DR3 (TNFRSF25) and is required for autoimmune pathology driven by diverse T-cell subsets. TL1A has been linked to human inflammatory bowel disease (IBD), but its pathogenic role is not known. We generated transgenic mice that constitutively express TL1A in T cells or dendritic cells. These mice spontaneously develop IL-13-dependent inflammatory small bowel pathology that strikingly resembles the intestinal response to nematode infections. These changes were dependent on the presence of a polyclonal T-cell receptor (TCR) repertoire, suggesting that they are driven by components in the intestinal flora. Forkhead box P3 (FoxP3)-positive regulatory T cells (Tregs) were present in increased numbers despite the fact that TL1A suppresses the generation of inducible Tregs. Finally, blocking TL1A-DR3 interactions abrogates 2,4,6 trinitrobenzenesulfonic acid (TNBS) colitis, indicating that these interactions influence other causes of intestinal inflammation as well. These results establish a novel link between TL1A and interleukin 13 (IL-13) responses that results in small intestinal inflammation, and also establish that TL1A-DR3 interactions are necessary and sufficient for T cell-dependent IBD.
Subject(s)
Enteritis/immunology , Interleukin-13/immunology , Tumor Necrosis Factor Ligand Superfamily Member 15/immunology , Animals , CD2 Antigens/genetics , CD2 Antigens/immunology , Colitis/immunology , Colitis/pathology , Dendritic Cells/immunology , Dose-Response Relationship, Immunologic , Enteritis/pathology , Forkhead Transcription Factors/metabolism , Gene Expression Regulation/immunology , Gene Order , HEK293 Cells , Humans , Immunologic Memory/immunology , Inflammatory Bowel Diseases/immunology , Inflammatory Bowel Diseases/pathology , Interleukin-13/genetics , Lymphocyte Activation/immunology , Mice , Mice, Inbred C57BL , Mice, Transgenic , Promoter Regions, Genetic , Receptors, Tumor Necrosis Factor, Member 25/metabolism , T-LymphocytesABSTRACT
OBJECTIVE: Signal transducers and activators of transcription (STATs) are crucial mediators of cytokine signalling. Constitutive activation of STATs, especially STAT3, has been reported in several diseases. Primary Sjögren's syndrome (pSS) is associated with overproduction of cytokines such as interleukin-10 (IL-10), although the mechanism by which this occurs is unknown. As STAT3 is a potent inducer of IL-10, this study focused on determining the pattern of STAT3 activation in peripheral lymphocytes from patients with pSS. METHODS: Twelve pSS patients and 12 healthy age-matched control subjects were studied. Peripheral blood mononuclear cells (PBMCs) were isolated by gradient centrifugation. Phosphorylated STAT3 (pSTAT3) and also STAT3 expression were determined by flow cytometry in gated CD3(+ )and CD19(+) lymphocytes. Similarly, pJak1 and pTyk2 were also determined in gated CD3(+) lymphocytes. RESULTS: Although the protein expression of STAT3 was similar among controls and pSS patients, we found that STAT3 was constitutively activated in CD3(+) lymphocytes from pSS patients. Neither Jak1 nor Tyk2 (the upstream activators of STAT3) was activated in pSS CD3(+) lymphocytes, suggesting that the constitutive activation of STAT3 observed in pSS patients might not depend on cytokine stimulation but instead might be the result of an abnormal inactivation of pSTAT3. CONCLUSIONS: These data provide evidence of abnormal STAT3 signalling in T cells from pSS patients.
