IL-6 cytokine family and signal transduction: a model of the cytokine system

The interleukin 6 (IL-6) cytokine family, which includes IL-6, leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF), IL-11 and cardiotrophin-1 (CT-1), exhibits pleiotropy and redundancy in biological activities. The IL-6 family cytokines exhibit a helical structure. Their receptors belong to the type 1 cytokine receptor family. The receptors of the IL-6 family cytokines share a receptor subunit, which explains one of the mechanisms of functional redundancy. In this review, we describe the general features of the IL-6 cytokine family and its signal transduction mechanisms. Many functional properties of the IL-6 family of cytokines and their receptors are general features of the cytokine system.     

Interleukin 9 and its Receptor: An Overview of Structure and Function

Interleukin-9 (IL-9) is a multifunctional cytokine produced by activated TH2 clones in vitro and during TH2-like T cell responses in vivo. Although IL-9 was initially described as a T cell growth factor, its role in T cell responses is still unclear. While freshly isolated normal T cells do not respond to IL-9, this cytokine induces the proliferation of murine T cell lymphomas in vitro, and in vivo overexpression of IL-9 results in the development of thymic lymphomas. In the human, the existence of an IL-9 mediated autocrine loop has been suggested for some malignancies such as Hodgkin's disease. Various observations indicate that IL-9 is actively involved in mast cells responses by inducing the proliferation and differentiation of these cells. Other potential biological targets for IL-9 include B lymphocytes, and hematopoietic progenitors, for which higher responses were observed with foetal or transformed cells as compared to normal adult progenitors. The IL-9 receptor is a member of the hemopoietin receptor superfamily and interacts with the 7 chain of the IL-2 receptor for signaling. Signal transduction studies have stressed the role of the Jak-STAT pathway in various IL-9 bioactivities, whereas the 4PS/IRS2 adaptor protein might also play a significant role in IL-9 signaling.     

人类Toll样受体信号转导途径及其介导的免疫作用

人类Toll样受体（TLR）是近年来发现的一类新的细胞表面信号传导跨膜受体,是人体固有免疫和适应性免疫的桥梁。TLR4组织分布较广泛,激活后通过TLR4-NF-κB信号途径促进细胞因子合成、激活T细胞、调节Th1／Th2免疫反应的平衡,从而调节机体的免疫状态。进一步研究TLR4的信号转导途径及其在疾病发展过程中的表达情况,可以为临床预防和治疗疾病提供新的思路和方法。     

IL-9 and its Receptor: From Signal Transduction to Tumorigenesis

IL-9 is a multifunctional cytokine secreted by TH2 lymphocytes. Besides its role during immune responses, its growth factor and antiapoptotic activities on multiple transformed cells suggest a potential role in tumorigenesis. Indeed, IL-9 overexpression induces thymic lymphomas in mice, and IL-9 production is associated with Hodgkin disease and HTLV-I transformed T cells in humans. IL-9 activities are mediated by a specific receptor chain that forms a heterodimeric receptor with the common gamma chain also involved in IL-2,4,7,15 and 21 signaling. The IL-9 receptor and common gamma chains associate with JAK1 and JAK3, respectively and trigger the STAT-1, -3 and -5, IRS and RAS-MAPK pathways. Moreover, in vitro, dysregulated IL-9 response can lead to autonomous cell growth and malignant transformation of lymphoid cells associated with constitutive activation of the Jak/STAT pathway.     

Interaction Between Interleukin 10 and Interleukin 6 in Human B-Cell Differentiation

Contrary to their opposing action on human T-lymphocytes and monocytes, both Interleukin (IL-)10 and IL-6 are potent differentiation factors of human B-cells. Both are known to induce immunoglobulin (Ig) production. The precise mechanism of this converging effect of IL-6 and IL-10 remains elusive, however. Here we investigated the role of IL-6 in the IL-10 dependent B-cell differentiation into Ig secreting cells. We found that co-stimulation of SAC-stimulated human peripheral B-lymphocytes with IL-10 and IL-6 exhibited no additive effect on Ig production over stimulation with IL-10 alone, and that IL-6 receptor blockade only mildly inhibited IL-10 induced Ig synthesis. In fact, we could show that stimulation of B-cells with IL-10 somewhat suppressed SAC induced autocrine IL-6 production. Despite this suppression IL-6 levels remained sufficiently high to stimulate its receptor, and IL-6 binding to the B-cell surface was not affected. The failure of IL-6 to exert an additional effect on SAC+IL-10 induced Ig production suggests that IL-10 may recruit components of the IL-6 intracellular pathway for Ig induction. In conclusion we could demonstrate that IL-10 acts on B-cell differentiation independently of autocrine IL-6 and that it had a considerably mild effect on B lymphocytic autocrine IL-6 secretion. This still allows an IL-6 effect in the presence of IL-10 which appears adaptive with a view to the converging effects of these two cytokines on human B lymphocytes. Our study thus adds to the appreciation of the complex cytokine regulation of the immune system.     

Interaction Between Interleukin 10 and Interleukin 6 in Human B-Cell Differentiation

Contrary to their opposing action on human T-lymphocytes and monocytes, both Interleukin (IL-)10 and IL-6 are potent differentiation factors of human B-cells. Both are known to induce immunoglobulin (Ig) production. The precise mechanism of this converging effect of IL-6 and IL-10 remains elusive, however. Here we investigated the role of IL-6 in the IL-10 dependent B-cell differentiation into Ig secreting cells. We found that co-stimulation of SAC-stimulated human peripheral B-lymphocytes with IL-10 and IL-6 exhibited no additive effect on Ig production over stimulation with IL-10 alone, and that IL-6 receptor blockade only mildly inhibited IL-10 induced Ig synthesis. In fact, we could show that stimulation of B-cells with IL-10 somewhat suppressed SAC induced autocrine IL-6 production. Despite this suppression IL-6 levels remained sufficiently high to stimulate its receptor, and IL-6 binding to the B-cell surface was not affected. The failure of IL-6 to exert an additional effect on SAC+IL-10 induced Ig production suggests that IL-10 may recruit components of the IL-6 intracellular pathway for Ig induction. In conclusion we could demonstrate that IL-10 acts on B-cell differentiation independently of autocrine IL-6 and that it had a considerably mild effect on B lymphocytic autocrine IL-6 secretion. This still allows an IL-6 effect in the presence of IL-10 which appears adaptive with a view to the converging effects of these two cytokines on human B lymphocytes. Our study thus adds to the appreciation of the complex cytokine regulation of the immune system.     

IL—6信号转导与转录激活子活性研究

目的　探讨 Ｉ Ｌ６ 生物效应与胞内磷酸化蛋白和转录激活子活性变化之间的关系。方法　应用原位杂交和 Ａ Ｐ Ａ Ａ Ｐ 方法检测细胞内 Ｉ Ｌ６ Ｒ ｍ Ｒ Ｎ Ａ 和蛋白的表达;采用 Ｄ Ｎ Ａ 结合蛋白凝胶阻滞电泳分析 Ｉ Ｌ６ 信号转导与 Ａ Ｐ Ｒ Ｆ 活性的相关性;用免疫沉淀和 Ｓ Ｄ Ｓ Ｐ Ａ Ｇ Ｅ 观察 Ｉ Ｌ６ 信号转导中磷酸化蛋白的变化情况。结果　（１） Ｉ Ｌ６ 受体（ Ｉ Ｌ６ Ｒ） ｍ Ｒ Ｎ Ａ 和蛋白表达阳性的人骨髓瘤细胞系（ Ｓ Ｋ Ｏ００７） 体外对 Ｉ Ｌ６ 有增殖反应;（２） 胞内转录激活子活性与 Ｉ Ｌ６ 诱导时间和剂量有相关性,抗ｇｐ１３０ 单克隆抗体和酪氨酸蛋白激酶抑制剂均可特异性抑制转录激活子活性;（３） Ｉ Ｌ６ 诱导 Ｓ Ｋ Ｏ００７细胞后,胞浆内出现一组相对分子质量为（１３０ 、９０ 、５４ 、３６） ×１０３ 磷酸化蛋白,它们的磷酸化活性与转录激活子活性一样,也具有时间和剂量相关性。结论　结果提示,转录激活子和这组相对分子质量不同的酪氨酸磷酸化蛋白参与 Ｉ Ｌ６ 信号转导调节。     

Inhibition of IL-6 family cytokines by SOCS3

IL-6 a multi-functional cytokine with important effects in both inflammation and haematopoiesis. SOCS3 is the primary inhibitor of IL-6 signalling, interacting with gp130, the common shared chain of the IL-6 family of cytokines, and JAK1, JAK2 and TYK2 to control both the duration of signalling and the biological response. Recent biochemical and structural studies have shown SOCS3 binds to only these three JAKs, all of which are associated with IL-6 signalling, and not JAK3. This specificity is determined by a three residue “GQM” motif in the kinase domain of JAK1, JAK2 and TYK2. SOCS3 binds to JAK and gp130 simultaneously, and inhibits JAK activity in an ATP-independent manner by partially occluding the kinase's substrate binding groove with its kinase inhibitory region. We therefore propose a model in which each of gp130, JAK and SOCS3 are directly bound to the other two, allowing SOCS3 to inhibit IL6 signalling with high potency and specificity.     

酪氨酸蛋白激酶JAK1 在IL-6诱导JAK/STAT 途径活化中的作用

目的 酪氨酸蛋白激酶JAK1和转录因子STAT3为参与IL－6诱导的JAK／STAT信号转导途径的两种主要的信号蛋白分子。本研究试图揭示JAK1在JAK／STAT途径诱导活化中的作用。方法 分别采用凝胶阻滞电泳（EMSA）和免疫沉淀（IP）法观察IL－6刺激作用下STAT3和JAK1在3种骨髓瘤细胞系（XG－7，KM－3和Sko-007)中的诱导活化状态。采用RTPCR和Western-blot法检测这两种信号蛋白分子在以上3株靶细胞中的表达情况。结果 尽管SAT3在3株靶细胞中都能够正常表达，但只有Sko-007细胞中出现IL－6刺激作用下STAT3的诱导活化。在XG－7细胞中，既没有检测到JAK1的表达，也没有观察到JAK1的活化。尽管JAK1在KM－3细胞中能够正常表达，但不能被IL－6诱导激活。Sko-007细胞中则同时出现JAK1的表达及IL－6刺激后的诱导活化。结论 JAK1的正常表达和激活是IL－6刺激作用下JAK／STAT信号转导途径在骨髓瘤细胞中诱导活化的前提条件。     

Interleukin 6 is not necessary for STAT3 phosphorylation and myocardial hypertrophy following short term beta-adrenergic stimulation

PurposeIn recent years several reports have suggested involvement of interleukin 6 (IL-6) in beta-adrenergic effects on myocardium, particularly in enhancement of STAT3 phosphorylation (downstream signal transducer of IL-6). Here we present a study of isoproterenol effects on hearts of IL-6 deficient mice.MethodsMale 12 week old C57Bl6/J mice and age and sex matched mice from IL-6 knockout strain (C57B16/J^IL6-/?) received a single intraperitoneal bolus of either isoproterenol (15 mg/kg) or placebo (0.9% NaCl) and were sacrificed after 1 or 24 hours (n=8 in each group). Another group of mice from both genotypes received a three-day isoproterenol treatment (20 mg/kg every 8h). Activation of STAT3 and MEK/ERK pathways were assessed after a single dose of isoproterenol by means of western blotting.ResultsAfter injection of placebo a significantly lower level of STAT3 phosphorylation was observed in IL-6 KO animals. This difference was abolished after isoproterenol both at 1 and 24-hour time points. Isoproterenol produced potent and rapid activation of both STAT3 and MEK/ERK pathways that returned to the levels of placebo treated controls after 24 hours. Lack of IL-6 did not affect phosphorylation of ERKs. Three-day treatment with isoproterenol caused significant increase of indices of RV and LV hypertrophy in both WT and IL-6 KO animals with no significant differences between genotypes.ConclusionIL-6 is not necessary for isoproterenol induced STAT3 phosphorylation, but may affect activation of this pathway by mild non-specific stimuli. Lack of IL-6 does not affect activation of MEK/ERK pathway nor cardiac hypertrophy by beta-adrenergic agonists.     

IL—6在人骨髓瘤细胞U266中的信号转导途径与细胞增殖促进效应之间的关系

目的：研究人骨髓瘤细胞U266中IL－6信号转导途径激活与细胞增殖促进效应之间的关系。方法：首先分别采用MTT、凝胶阻滞电泳（electrwophoretic mobility shift assay, EMSA）和免疫沉淀（immunoprecipitation,IP）方法观察IL－6对U266细胞生长的影响及两条IL－6信号转导途径在U266细胞中的诱导激活状态;然后采用化学试剂处理或转基因方法观察信号途径活化状态变化与IL－6效应变化之间的关系。结果：IL－6可明显促进U266细胞增殖,并在不同剂量下诱导JAK／STAT和Ras/NF-IL-6途径活化;Ras途径活化被特异性上调和下调时,IL－6对U266细胞的生长促进效应分别得以增强和减弱;而JAK／STAT途径活化受抑时,IL－6的促细胞生长效应反而加强。结论：Ras途径的诱导激活介导了IL－6对U266细胞的增殖促进效应;而JAK／STAT途径活化介导了与IL－6促细胞增殖相反的生物学效应。     

人可溶性IL-6R基因在COS7细胞中的表达及活性分析

目的在ＣＯＳ７细胞中表达具有生物学功能的人可溶性ＩＬ－６Ｒ（ｓＩＬ－６Ｒ），作为研究ｓＩＬ－６Ｒ结构与功能关系的基础。方法首先利用ＰＣＲ技术扩增出人可溶性ＩＬ－６Ｒ（ｈｓＩＬ－６Ｒ）编码基因片段，并重组入克隆载体ｐＡＬＴＥＲ－１。通过基因序列分析确定了目的基因的核苷酸序列，并进一步构建了由ＳＶ４０晚期启动子和ＨＣＭＶ早期启动子控制的表达质粒ｐＳＶＬ６Ｒ和ｐＣＭＶ６Ｒ。用脂质体介导的方法将表达质粒转染ＣＯＳ７细胞，并分别在ｍＲＮＡ水平（斑点杂交）和蛋白水平（ＥＬＩＳＡ和Ｗｅｓｔｅｒｎ－ｂｌｏｔ）检测ｓＩＬ－６Ｒ基因在ＣＯＳ７细胞中的表达。在７ＴＤ１，ＬＴ１２两种ＩＬ－６反应细胞系上检测转染细胞上清（含ｓＩＬ－６Ｒ）的生物学活性。结果在ｍＲＮＡ水平和蛋白水平分别检测到ｓＩＬ－６Ｒ基因在ＣＯＳ７细胞中的表达，表达产物分子量约为５００００。表达产物在７ＴＤ１，ＬＴ１２细胞系上检测到明显的生物学活性。结论天然ｓＩＬ－６Ｒ基因在ＣＯＳ７细胞中的成功表达为进一步制备ｓＩＬ－６Ｒ突变体及其结构与功能关系的研究奠定了基础     

Interleukin-6 Receptor Polymorphisms Contribute to the Neurological Status of Korean Patients with Ischemic Stroke

To investigate the contribution of the interleukin-6 receptor (IL-6R) gene single nucleotide polymorphisms (SNPs) to the neurological status of Korean patients with ischemic stroke (IS), two SNPs of the IL-6R gene (rs4845617, 5 UTR; rs2228144, Ala31Ala) were selected. IS patients were classified into clinical phenotypes according to two well-defined scores: the National Institutes of Health Stroke Survey (NIHSS) and the Modified Barthel Index scores. There were 121 IS patients and 291 control subjects. The SNP rs4845617 significantly contributed to the neurological status of patients with IS (P = 0.011 in codominant model 2, P = 0.006 in recessive model, and P = 0.008 in log-additive model). Allele frequencies of rs4845617 and rs2228144 demonstrated no significant difference in IS patients and controls. The AG and GG haplotypes differed between the NIHSS 1 (NIHSS scores < 6) group and the NIHSS 2 (NIHSS scores ≥ 6) group in patients with IS (P = 0.014, P = 0.0024). These results suggest that rs4845617 of the IL-6R gene is associated with the neurologic status of Korean patients with IS.     

狼疮肾炎PBMC高表达抗ds-DNA抗体和IL-6由MAPKERK1/2通路介导

目的：探讨有丝分裂原激活的蛋白激酶-细胞外调节激酶1/2（MAPKERK1/2）信号通路在系统性红斑狼疮合并肾炎（LN）患者外周血单个核细胞（PBMC）中自发高水平表达白细胞介素6（IL-6）和抗双链DNA抗体（抗ds-DNA抗体）中的作用。 方法： 分离培养患者PBMC，利用蛋白免疫印迹法、逆转录PCR 法和酶联免疫吸附法分别检测MAPKERK1/2磷酸化活化程度、IL-6表达和抗ds-DNA抗体水平，并与正常对照组比较。 结果： 26例LN患者与21例健康对照者比较，体外培养LN患者PBMC MAPKERK1/2信号通路呈高度活化状态，并自发表达高水平IL-6和抗ds-DNA抗体，组间有显著差异(P<0.05)。应用特异性阻断剂PD98059阻断LN患者PBMC MAPKERK1/2信号通路活化可显著抑制IL-6 和抗ds-DNA抗体的自发高表达。 结论： LN患者PBMC中MAPKERK1/2信号通路异常活化，并介导PBMC自发高水平表达IL-6 和抗ds-DNA抗体。     

Ⅱ型糖尿病患者血、尿白介素-6变化的意义

目的 :探讨II型糖尿病 (DM)患者血、尿白介素 6 (interleukin 6 ,IL 6 )水平的变化 ,了解IL 6在糖尿病肾病中的发病学意义。方法 :用放射免疫法检测 4 5例II型糖尿病患者及 2 0例正常人血、尿IL 6水平并进行比较。结果 :(1)II型糖尿病患者血、尿IL 6水平明显高于正常人 (P <0 0 5或P <0 0 1)。 (2 )早期糖尿病肾病患者尿IL 6水平明显高于单纯糖尿病患者(P<0 0 5 )。 (3)患者血IL 6水平分别与病程和空腹胰岛素 (fastinginsulin ,FINS)水平呈正相关 (r=0 30 5和 0 32 9,P 均 <0 0 5 ) ,与胰岛素敏感指数 (insulinsensitiveindex ,ISI)呈负相关 (r =- 0 35 2 ,P <0 0 2 ) ,尿IL 6水平分别与病程和尿白蛋白排泄率 (urinealbuminexcretionrate ,UAER)呈正相关 (r =0 32 6 ,P <0 0 5 ;r =0 4 6 6 ,P <0 0 1)。结论 :患者体内高水平的血清IL 6可能是II型糖尿病胰岛素抵抗病理生理改变的一种表现 ,IL 6可能参与糖尿病肾病的发生发展 ,尿IL 6水平对糖尿病肾病的病情分析有重要临床意义。