Genetic control of interleukin-4-induced activation of the human signal transducer and activator of transcription 6 signaling pathway

The interleukin (IL)-4-induced Stat6 signaling pathway is active in a variety of cell types, including immune cells and cancer cells, and plays an important role in the regulation of gene expression, such as CD23 and major histocompatibility complex class II. Using a semiquantitative gel shift assay in which nuclear Stat6 activities were scored, three Stat6 activation phenotypes were defined as Stat6(high) (intense banding), Stat6(low) (medium intensity banding), and Stat6(null) (very low to no discernible banding). These Stat6 phenotypes correlated well with levels of CD23 expression, but not with those of human leukocyte antigen-DR cell-surface display. Pedigree analyses revealed a Mendelian inheritance pattern that can be explained by two STAT6 Pathway (STAT6P) activation genotypes, which we term A and a, where STAT6P*A determines an active Stat6 signaling and STAT6P*a determines an inactive Stat6 signaling, with incomplete dominance. Total Stat6 protein levels failed to correlate with the above Stat6 phenotypes allowing us to propose that IL-4-induced Stat6 signaling is a polygenic quantitative trait regulated by a collection of several contributing genetic loci that functionally interact. The Stat6(null) phenotype may result from a defect in Stat6 signaling, which has important implications with respect to the pathogenesis of cancer and Th1/Th2 cytokine imbalance in autoimmune diseases in general.     

Interleukin-6 receptor-mediated activation of signal transducer and activator of transcription-3 (STAT3) promotes choroidal neovascularization

Interleukin (IL)-6, a potent proinflammatory cytokine, is suggested to be a risk factor for choroidal neovascularization (CNV) because of its increased levels in the serum of patients with age-related macular degeneration; however, the role of IL-6 in CNV has not been defined. The present study reveals the critical contribution of IL-6 signaling and its downstream STAT3 pathway to the murine model of laser-induced CNV. CNV induction by laser treatment stimulated IL-6 expression in the retinal pigment epithelium-choroid complex, and antibody-based blockade of IL-6 receptor or genetic ablation of IL-6 led to significant suppression of CNV. CNV generation was accompanied by STAT3 activation in choroidal endothelial cells and macrophages, and IL-6 receptor blockade resulted in selectively inhibited phosphorylation of STAT3 but not extracellular signal-regulated kinase 1/2. Consistently, pharmacological blockade of STAT3 pathway also suppressed CNV. In addition, IL-6 receptor neutralization led to significant inhibition of the in vivo and in vitro expression of inflammation-related molecules including monocyte chemotactic protein, intercellular adhesion molecule-1, and vascular endothelial growth factor, and of macrophage infiltration into CNV. These results indicate the significant involvement of IL-6 receptor-mediated activation of STAT3 inflammatory pathway in CNV generation, suggesting the possibility of IL-6 receptor blockade as a therapeutic strategy to suppress CNV associated with age-related macular degeneration.     

Suppression of activation of signal transducer and activator of transcription-5B signaling in the vessel wall reduces balloon injury-induced neointima formation

Previously, we have demonstrated that STAT-5B plays a role in thrombin-induced vascular smooth muscle cell (VSMC) growth and motility. To learn more about the role of STAT-5B in vessel wall remodeling, we examined its involvement in platelet-derived growth factor-BB (PDGF-BB)-stimulated VSMC growth and motility and balloon injury-induced neointima formation. PDGF-BB activated STAT-5B as measured by its tyrosine phosphorylation, DNA binding, and reporter gene activity. PDGF-BB induced cyclin D1 expression, CDK4 activity, and Rb protein phosphorylation, leading to VSMC growth and motility, and these responses were suppressed by the blockade of STAT-5B. Increased cyclin D1 levels, CDK4 activity, and Rb protein phosphorylation were observed in 1-week balloon-injured arteries compared with uninjured arteries, and these responses were also suppressed by adenovirus-mediated expression of dnSTAT-5B. In addition, adenovirus-mediated expression of dnSTAT-5B attenuated balloon injury-induced smooth muscle cell migration from media to intima and their proliferation in intima, resulting in reduced neointima formation. These observations indicate that STAT-5B plays an important role in PDGF-BB-induced VSMC growth and motility in vitro and balloon injury-induced neointima formation in vivo.     

Staphylococcal enterotoxin B in vivo modulates both gamma interferon receptor expression and ligand-induced activation of signal transducer and activator of transcription 1 in T cells

Superantigens (SAg) are bacterial exotoxins that provoke extreme responses in the immune system; for example, the acute hyperactivation of SAg-reactive T cells that leads to toxic shock syndrome is followed within days by strong immunosuppression. The gamma interferon (IFN-gamma) response is deeply affected in both extremes. The implication of IFN-gamma in the pathophysiology of lethal shock induced in mice after a secondary challenge with the SAg staphylococcal enterotoxin B (SEB) prompted us to study the regulation of IFN-gamma secretion and the intracellular response. We demonstrate in this study that a rechallenge with SEB becomes lethal only when given inside a critical time window after SEB priming and is associated with an increase of IFN-gamma serum release 72 h after priming. However, at this time, a selective blockade of IFN-gamma/STAT1 signaling develops in spleen cells, correlating with a lack of expression of the IFN-gamma receptor beta subunit and STAT1 in the T-cell population. Selective blockade of the STAT1 signaling pathway--while simultaneously maintaining STAT3 signaling and expression--may be a protective mechanism that shortens IFN-gamma production during the Th1 effector response. This blockade may also have consequences on switching towards a suppressor phenotype with chronic exposure to the superantigen.     

乳腺癌患者原发磷酸化信号转导与转录激活因子3活性和白细胞介素-17表达的临床意义

目的 探讨炎性信号通路磷酸化信号转导和转录激活因子3（p-STAT）的原发活化状态及下游细胞因子白细胞介素（IL）-17表达在乳腺癌发生和发展中的作用及其对预后的影响。 方法 运用免疫组织化学Envision两步法检测了379例乳腺癌患者以及匹配癌旁245例乳腺腺病中IL-17表达和原发性p-STAT3的活化状态,分析了它们与乳腺癌组织学分型、TNM分期、临床分期及预后的相关性。统计学分析：计量数据使用t检验法,计数数据使用χ2 检验法。结果 1. IL-17在乳腺癌中的阳性表达率为95.8%,显著高于乳腺腺病中的阳性表达率85.3%（χ2=21.363,P<0.001）;具有活性的p-STAT3在乳腺癌中的阳性率为93.6%,也显著高于乳腺腺病中的阳性率62.0%（χ2=97.702,P<0.001）。2. IL-17和p-STAT3在乳腺癌 (包括乳腺浸润性导管癌、乳腺浸润性小叶癌和腺导管原位癌分型) 中的阳性率与乳腺癌组织学分型无相关性（χ2=1.245, P=0.535＞0.05）。3. IL-17和p-STAT3在乳腺癌中的强阳性率分别与淋巴结的转移成正相关（IL-17: χ2=7.806, P<0.01; p-STAT3: χ2=4.053, P<0.05）。4. 在乳腺癌组织中,IL-17表达与p-STAT3活性呈正相关（rs=0.136, P<0.01）。 结论 原发增高的p-STAT3活性及高表达的炎性细胞因子IL-17可能协同作用,产生炎性微环境,从而参与乳腺癌的发生和发展。