信号转导子和转录激活子与Th1／Th2平衡在支气管哮喘中的作用研究

支气管哮喘是慢性气道炎症性疾病。在其发生、发展中，胞外信号分子、信号转导、信号转导子和转录激活子3个环节调控着Th细胞的分化。而Th1／Th2细胞失衡，细胞因子分泌紊乱，使气道炎症持续存在。其中STAT4和STAT6起关键作用。本文就STAT4和STAT6调控Th细胞分化的机制及研究进展作一综述。     

嗜酸粒细胞凋亡在支气管哮喘中的调控

嗜酸粒细胞(EOS)是哮喘炎症中的重要致炎细胞,EOS凋亡及其调控在哮喘发生、发展中起重要作用。本文从细胞、细胞因子、免疫分子及信号转导、基因调控等方面探论EOS凋亡的调控因素及机制。     

信号转导子和转录激活子与Th1/Th2平衡在支气管哮喘中的作用研究

支气管哮喘是慢性气道炎症性疾病.在其发生、发展中,胞外信号分子、信号转导、信号转导子和转录激活子3个环节调控着Th细胞的分化.而Th1/Th2细胞失衡.细胞因子分泌紊乱,使气道炎症持续存在,其中STAT4和STAT6起关键作用.本文就STAT4和STAT6调控Th细胞分化的机制及研究进展作一综述.     

细胞因子信号转导抑制因子1与肺部疾病

细胞因子信号转导抑制因子1(suppressor of cytokine signaling-1,SOCS1)能反馈性抑制干扰素、白介素4等多种细胞因子的信号转导,在转录、翻译、蛋白各水平受到精密调控.适当的SOCS1表达可抑制哮喘的炎症反应,但不恰当的SOCS1表达可能增加发生哮喘的几率.在肺部感染中,SOCS1能防...     

嗜酸粒细胞凋亡在支气管哮喘中的调控

嗜酸粒细胞（EOS）是哮喘炎症中的重要致炎细胞，EOS凋亡及其调控在哮喘发生，发展中起重要作用。本文从细胞，细胞因子，免疫分子及信号转导，基因调控等方面探论EOS凋亡的调控因素及机制。     

JAK/STAT信号转导通路在肝纤维化形成中的作用

JAK/STAT信号转导通路是一条由多种细胞因子和生长因子介导的信号转导通路,能参与细胞的增殖、分化、凋亡及炎症等病理生理过程。研究表明,JAK/STAT通路在肝纤维化的形成进程中具有重要的调控作用。本文就近年JAK/STAT信号转导通路在肝纤维化形成过程中的作用作一综述。     

细胞因子信号转导抑制因子1在肝脏炎症性疾病发生发展中的作用机制

肝脏炎症性疾病的发生与自身免疫和炎症反应有关,细胞因子信号转导抑制因子1(SOCS1)作为一种细胞信号的负反馈调节因子,其在炎症性疾病的发生发展中起到关键作用。介绍了SOCS1在自身免疫与炎症反应中的作用机制,简述其在肝脏炎症性疾病如病毒性肝炎、非酒精性脂肪性肝炎等疾病发生、发展中的作用。分析表明SOCS1在炎症反应中的异常表达与细胞因子受体、Toll样受体和激素受体信号的调控有关,从而导致炎症性疾病的发生,因此SOCS1作为肝脏炎症性疾病诊断和治疗的辅助手段具有潜在的发展前景。     

慢性乙型肝炎信号转导及转录激活因子3、5与Treg/Th17平衡的关系

慢性乙型肝炎持续感染的免疫机制与T淋巴细胞密切相关,T淋巴细胞的发育需要多种细胞因子的协调作用,而信号转导及转录激活因子家族蛋白主要参与细胞因子的信号转导,尤其是STAT5a/b和STAT3在调节性T淋巴细胞(Treg)和辅助性T淋巴细胞17(Th17)的分化、发育过程中有着重要作用。本文主要就在慢性乙型肝炎中,对信号转导及转录激活因子3、5与Treg/Th17平衡的关系进行分析,研究HBV感染的慢性化及其引起的肝脏炎症调控机制。     

急性胰腺炎中胰腺腺泡细胞信号转导通路

急性胰腺炎(acute pancreatitis,AP)是一种炎症反应所致的胰腺腺泡细胞损伤、间质水肿和出血,并可导致局部和全身并发症.各种因素如胆结石、酒精、局部缺血、遗传等似乎都首先影响胰腺腺泡细胞,引起胰腺腺泡细胞胰酶活化,诱发局部炎症反应[1].AP发病机制中胰腺腺泡细胞受到多种细胞因子调控,这些细胞因子通过结合细胞表面受体,激活细胞内不同的信号转导通路,使胰腺腺泡细胞的功能结构发生变化.     

大鼠局灶性脑缺血再灌注后TNF-a、SOCS-3动态表达的实验研究

目的探讨肿瘤坏死因子-a（TNF—a）、细胞因子信号转导抑制因子-3（SOCS-3）在大鼠脑缺血再灌注后的动态表达及特点,阐明TNF-a、SOCS-3在脑缺血再灌注中的作用。方法将雄性sD大鼠48只随机分为假手术组和缺血3h再灌注3h、6h、12h、24h、48h、72h、7d组,6只／组。运用改良线栓法制作大鼠局灶性脑缺血再灌注模型。用放射免疫法测定TNF-a含量及用RT—PCR法测定SOCS-3的含量。结果TNF-a含量变化：与假手术组比较,缺血再灌注纽脑组织TNF—a含量在6h明显增加,12h达到高峰,随后各时间点表达开始下降。在缺血半暗带区,TNF—a含量变化与中心区相同,但含量较低。SOCS-3mRNA含量变化：缺血再灌注组缺血中心区SOCS-3表达在6h开始有明显升高与假手术组相比有显著性差异,再灌注24h时达到高峰,随后备时间点表达相对稳定,至再灌注7d时仍过分表达。在缺血半暗带区,SOCS～3mRNA变化与中心区相同,但含量较低。结论TNF—α在大鼠局灶性脑缺血再灌注损伤中具有重要作用,可诱导SOCS-3基因的产生和表达。而SOCS-3基因是一个脑缺血后上调基因,它参与了脑缺血再灌注损伤的全过程,可能起到了内源性神经保护剂的作用。     

STAT5b mediates the GH-induced expression of SOCS-2 and SOCS-3 mRNA in the liver

Suppressor of cytokine signalling (SOCS) proteins act as part of a classical negative feedback loop regulating cytokine signal transduction. Expression of SOCS proteins is induced in response to cytokines and down-regulates the cytokine signal by inhibiting the JAK/STAT pathway. Growth hormone (GH) was previously shown to induce strong transient expression of SOCS-3 and to a lesser extent CIS, SOCS-1 and SOCS-2 in mouse liver (Adams, T.E., Hansen, J.A., Starr, R., Nicola, N.A., Hilton, D.J., Billestrup, N., 1998. Growth hormone preferentially induces the rapid, transient expression of SOCS-3, a novel inhibitor of cytokine receptor signalling. J. Biol. Chem. 273, 1285-1287.). In this work we have compared GH-induced SOCS gene expression in wild-type and STAT5b-deficient mice, and show that STAT5b is required for the induction of SOCS-2 and SOCS-3 in liver. In contrast, the absence of STAT5b has no effect on the GH-induced expression of CIS and SOCS-2 mRNA in the mammary gland. Suprisingly, there is no activation of SOCS-3 expression in mammary glands of wild-type and STAT5b mutant mice following GH administration. These results highlight both tissue- and factor-specific differences in the regulation of SOCS gene expression by STAT5a/b.     

Suppressor of cytokine signaling (SOCS)-5 is a potential negative regulator of epidermal growth factor signaling

The suppressors of cytokine signaling (SOCS) proteins are a family of SH2 domain-containing intracellular inhibitors of cytokine signal transduction that act by several different mechanisms. Recent evidence suggests that the action of the SOCS proteins may extend beyond the cytokine receptors to signaling initiated by members of the tyrosine kinase receptor family. In this study, the ability of SOCS-5 to negatively regulate signaling cascades downstream of the epidermal growth factor receptor (EGF-R) has been examined by using an EGF-responsive cell line engineered to constitutively express the EGF-R and SOCS-5 or SOCS-5 mutants. SOCS-5 associated with the EGF-R complex in an EGF-independent manner, and the mitogenic response to EGF of all SOCS-5-expressing cell lines was dramatically inhibited when compared with control cell lines. Furthermore, this effect was abrogated after deletion of the SOCS-5 SOCS box. This result suggests that the inhibition of signaling occurs through enhanced proteasomal degradation of the EGF-R through SOCS box recruitment of E3 ubiquitin ligase activity.     

Role of suppressors of cytokine signaling SOCS-1 and SOCS-3 in hepatic steatosis and the metabolic syndrome.

Insulin resistance, obesity, diabetes, dyslipidemia and nonalcoholic fatty liver are components of the metabolic syndrome, a disease complex that is increasing at epidemic rates in westernized countries. Although proinflammatory cytokines have been suggested to contribute to the development of these disorders, the molecular mechanism of the development of this syndrome is poorly understood. In this study, we show that expression of suppressor of cytokine signaling SOCS-1 and SOCS-3 is increased in livers of obese insulin-resistant animals, and that adenoviral-mediated overexpression of SOCS-1 or SOCS-3 in liver causes insulin resistance through down-regulation of tyrosine phosphorylation of insulin receptor substrate (IRS) proteins. Moreover, the increased SOCS-1 and SOCS-3 also cause a prominent up-regulation of the key regulator of fatty acid synthesis in liver, sterol regulatory element binding protein (SREBP)-1. Conversely, inhibition of SOCS-1 and SOCS-3 in livers of obese diabetic db/db mice by antisense treatment modestly improves insulin sensitivity, but completely normalizes the increased expression of SREBP-1. The latter leads to dramatic amelioration of hepatic steatosis and hypertriglyceridemia. Promoter activity analysis reveals that expression of SOCS-1 or SOCS-3 with SOCS-3 being more potent enhances SREBP-1c expression, while it is inhibited by expression of STAT3. This STAT3-mediated inhibition of SREBP-1c expression is antagonized by co-expression of SOCS proteins. Moreover, db/db mice display decreased STAT3 phosphorylation in liver that is normalized by antisense treatment of SOCS proteins. These data suggest that obese subjects in the persistent inflammatory states, such as elevated circulating tumor necrosis factor-alpha, may have down-regulated STAT3-mediated signaling by increased SOCS proteins, leading to up-regulation of SREBP-1c expression and increased fatty acid synthesis in liver. Thus, SOCS proteins play an important role in pathogenesis of the metabolic syndrome by concordantly modulating cytokine signaling and insulin signaling.     

Growth hormone reduces the severity of fibrosis associated with chronic intestinal inflammation

BACKGROUND & AIMS: Growth hormone (GH) is used to treat growth delay in children with Crohn's disease and in patients with short-bowel syndrome. GH can increase collagen accumulation in intestinal mesenchymal cells, raising concern that GH therapy could exacerbate fibrosis in patients with Crohn's disease. We tested if GH treatment altered inflammation or fibrosis during chronic, experimental granulomatous enterocolitis. METHODS: Ileum and cecum of Lewis rats were subserosally injected with peptidoglycan-polysaccharide (PG-APS) or control human serum albumin. At the onset of chronic PG-APS-induced inflammation, rats were administered recombinant human GH or vehicle for 14 days. Fibrosis and inflammation were quantified by gross gut disease scoring, histologic scoring, type I collagen, and cytokine expression in cecum. Abundance and localization of suppressor of cytokine signaling-3 (SOCS-3) messenger RNA and/or protein were determined in cecum. Effect of GH, cytokines, or PG-APS on SOCS-3 synthesis was measured in intestinal myofibroblasts. Myofibroblasts overexpressing SOCS-3 were used to test whether SOCS-3 inhibits collagen accumulation. RESULTS: In PG-APS-injected rats, GH modestly reduced gross adhesions and mesenteric contractions, cecal fibrosis score, and collagen expression, but had no effect on intestinal inflammation. GH increased SOCS-3 messenger RNA and protein abundance in PG-APS rats and SOCS-3 messenger RNA was localized to the periphery of granulomas. GH in combination with cytokines or PG-APS, but not alone, induced SOCS-3 synthesis in intestinal myofibroblasts. Myofibroblasts overexpressing SOCS-3 showed reduced cytokine-induced collagen accumulation. CONCLUSIONS: GH modestly reduces intestinal fibrosis associated with chronic experimental enterocolitis and stimulates expression of antifibrogenic SOCS-3, suggesting that GH therapy in inflammatory bowel disease should not exacerbate fibrosis.