Increased expression and activation of IL-12-induced Stat4 signaling in the mucosa of ulcerative colitis patients.
ABSTRACT Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory diseases with unsolved pathogenesis. Imbalanced Th1/Th2 may play a role in the sustained inflammation of IBD. In China, CD is rare but the incidence of UC has been rising steadily in the last two decades. We investigated the expression of IL-12 (p40) and IFN-gamma, and the activational state of Stat4 signaling in mucosal tissues at the site of disease from 30 active UC patients in comparison with 30 healthy controls. RT-PCR analyses revealed increased mRNA expression of IL-12 (p40) but not IFN-gamma in UC patients. Western blot analyses discovered, for the first time, increased levels of constitutive Stat4 in the cytoplasm and phosphorylated Stat4 in the nucleus of mucosal cells from UC patients. We conclude that a heightened, perhaps persistent, activational state of IL-12/Stat4, and/or IL-23/Stat4 signaling may be present in active Chinese UC patients, and possibly involved in chronic inflammation in UC.
- SourceAvailable from: Luis Rodrigo-Saez[Show abstract] [Hide abstract]
ABSTRACT: Recently, the signal transducer and activator of transcription 4 (STAT4) gene has been associated with multiple autoimmune diseases. Interestingly, a recent work showed that the T allele of the rs7574865 STAT4 SNP was associated with inflammatory bowel disease (IBD) in a Spanish population. The aim of the present study was to reevaluate the role of the STAT4 rs7574865 polymorphism on IBD. The present case-control study included 498 Crohn's disease (CD) patients, 402 ulcerative colitis (UC) patients, and 1296 healthy matched controls. Genotyping was performed using a PCR system with a pre-developed TaqMan allelic discrimination assay for the rs7574865 STAT4 SNP. Moreover, a meta-analysis was performed with the previous work in a Spanish population and the current study, including a final sample size of 1574 IBD patients (820 with CD and 754 with UC) and 2012 healthy controls. No evidence of association was found for the current case-control study (CD: p = 0.23, OR = 0.9, 95% CI = 0.75-1.1; UC: p = 0.17, OR = 1.14, 95% CI = 0.95-1.38). However, the meta-analysis showed that the STAT4 rs7574865 T allele was significantly associated with susceptibility to UC (p = 0.012 pooled; OR = 1.20, 95% CI = 1.04-1.39) but not CD (p = 0.71 pooled; OR = 0.93, 95% CI = 0.65-1.34). Our data suggest that the rs7574865 STAT4 SNP is a genetic susceptibility variant for UC but not CD in the Spanish population.Human immunology 02/2010; 71(5):515-9. DOI:10.1016/j.humimm.2010.02.005 · 2.28 Impact Factor
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ABSTRACT: PurposeTo investigate potential differences in the expression of Stat6 regulatory genes that may influence IL-4/Stat6 activities (phenotypes) in colon cancer cells. MethodsRT-PCR method was employed to examine the constitutive mRNA expression of Stat6 negative regulators SOCS-1 and SHP-1, and positive regulator PP2A in colon cancer cell lines HT-29 and Caco-2. Stat6 protein expression and nuclear phosphorylation were detected using Western blotting. ResultsCaco-2 cells carrying inactive Stat6null phenotype showed normal constitutive expression of Stat6 but decreased phosphorylation of nuclear Stat6 compared with HT-29 cells carrying active Stat6high phenotype. Stat6null Caco-2 cells expressed increased levels of mRNA and protein of SOCS-1 and SHP-1, and decreased mRNA expression of PPP2CA and PPP2CB, encoding two critical subunits of PP2A. ConclusionsConstitutively increased expression of Stat6 negative regulators SOCS-1 and SHP-1, together with decreased expression of positive regulator PP2A, may play a role in forming the inactive Stat6null phenotype in colon cancer cells.Journal of Cancer Research and Clinical Oncology 12/2008; 135(1):131-140. DOI:10.1007/s00432-008-0429-8 · 3.01 Impact Factor
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ABSTRACT: The differentiation of naïve CD4+ T cells into subsets of T helper cells (Th) is an essential process that impacts host defense and the pathogenesis of immunemediated diseases. Signal transducers and activators of transcription (STAT) proteins, activated downstream of instructive cytokines, dictate and perpetuate the lineage decision of Th cells through both positive and negative effects. This is accomplished by regulating transcription factors, surface receptors and promoting epigenetic changes in gene expression through chromatin remodeling. Transforming growth factor-β1 (TGF-β1) can induce Foxp3 in developing Th cells and these Foxp3-expressing adaptive T regulatory cells (aTregs) are able to suppress inflammation in vitro and in vivo. To define the mechanism by which STAT proteins regulate Th cell pro- and anti-inflammatory phenotypes, we examined T cells deficient in Stat3, Stat4, and Stat6 as well as T cells expressing two STAT4 isoforms after being cultured in the presence or absence of TGF-β1 and cytokines known to be instructive in Th cell development. The negative effects of STAT proteins are demonstrated by our results indicating STAT3, STAT4 and STAT6 proteins activated downstream of the instructive cytokines IL- 6, IL-12 and IL-4, respectively, negatively regulate the development of TGF-β induced Foxp3 and aTreg development. STAT3, STAT4, and STAT6 utilize a vi Mark H. Kaplan, Ph.D., Chair common mechanism to inhibit aTreg generation by inhibiting STAT5, a positive regulator of Foxp3 expression, from binding to the Foxp3 gene. STAT proteins positively effecting inflammatory immunity are demonstrated by our analysis of STAT4 isoforms and their ability to regulate the production of proinflammatory cytokines downstream of IL-12. STAT4β, a STAT4 splice isoform that lacks a Cterminal domain, and STAT4α, a full-length isoform are both capable of mediating inflammatory cell development. However, STAT4β promotes greater inflammation in vivo than STAT4α independent of its ability to repress Foxp3. Instead, the inflammation correlates with STAT4 isoform-dependent expression of inflammatory cytokines. Thus, cytokine-stimulated STAT proteins orchestrate T helper cell pro- and anti-inflammatory cell phenotypes.