CYTOKINE REGULATION OF RA SYNOVIOCYTE PHENOTYPE

RA滑膜细胞表型的细胞因子调控

• 批准号: 6171595
• 负责人: Lionel B Ivashkiv
• 金额: $ 22.22万
• 依托单位: HOSPITAL FOR SPECIAL SURGERY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-27 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6171595
• 关键词: JAK kinase; SDS polyacrylamide gel electrophoresis; biological signal transduction; cytokine; cytokine receptors; fibroblasts; flow cytometry; human tissue; immunoprecipitation; inhibitor /antagonist; interleukin 1; interleukin 10; interleukin 6; mitogen activated protein kinase; nucleic acid hybridization; pathologic process; phenotype; protein protein interaction; receptor expression; rheumatoid arthritis; scleroderma; synovial membrane; synovitis; tissue /cell culture; tumor necrosis factor alpha; western blottings

Certain pro-inflammatory cytokines, especially IL-1 and TNFalpha, are expressed in the majority of patients with RA and play an important role in pathogenesis. Important targets for pro-inflammatory cytokines are synovial fibroblasts, which proliferate, assume an invasive morphology, and invade and degrade cartilage. One striking characteristic of RA synovitis is the consistently high expression of immunosuppressive and anti-inflammatory cytokines, such as IL10 and TGF-beta, and of members of the IL-6 family of cytokines. Although IL-6-related cytokines have often been considered pro-inflammatory, more recent results suggest that they (and the downstream transcription factor Stat3) have anti-inflammatory actions on synovial fibroblasts and possibly macrophages. One major school of thought holds that the balance between pro- and anti-inflammatory factors determines the progression of disease, and that defects in the de-activation phase of inflammation play a critical role in the pathogenesis of RA. One important issue is why abundant expression of anti-inflammatory cytokines does not lead to resolution of inflammation in RA? We have explored the possibility that the anti-inflammatory actions of IL-10 and IL-6-related cytokines may be blocked in RA synovium at the level of signal transduction. We have found that IL-1, TNFalpha, and H2O2 suppress IL-6 and IL-10 activation of Stat3 DNA-binding and tyrosine phosphorylation by a mechanism that appears dependent on mitogen-activated protein kinases (MAPKs). Inhibition of Stat3 correlated with inhibition of expression of IL-6-inducible genes that have an anti-inflammatory function. We hypothesize that inhibition of IL-6 and IL-10 signaling and Stat3 activity by inflammatory factors that are present during synovitis contributes to pathogenesis by blocking de-activation of synovial inflammation. We propose to delineate the mechanisms underlying crosstalk between inflammatory/MAPK and IL-6/IL-10 Jak-STAT signaling pathways in synovial fibroblasts, and to investigate the functional consequences of this crosstalk in the context of RA pathogenesis. Greater understanding of mechanisms that block anti-inflammatory cytokine action will be helpful in designing novel therapeutic approaches to shift the balance of cytokine activity to limit inflammation and progression of disease. Our specific aims are to: (1) Identify the molecular mechanism by which the inflammatory cytokines IL-1 and TNFalpha, and ROIs, inhibit activation of Stat3 by IL-6-related cytokines and IL-10 in RA synovial fibroblasts. (2) Determine which MAPKs play an important role in inhibition of IL-6 and IL-10 signaling in RA synovial fibroblasts. (3) Characterize the functional consequences of modulation of IL-6 and IL-10 signal transduction by inflammatory factors on synovial fibroblast phenotype.

某些促炎细胞因子，特别是IL-1和TNF α，在大多数RA患者中表达，并在发病机制中起重要作用。 促炎细胞因子的重要靶点是滑膜成纤维细胞，其增殖，呈现侵入性形态，并侵入和降解软骨。 RA滑膜炎的一个显著特征是免疫抑制和抗炎细胞因子（如IL 10和TGF-β）以及细胞因子的IL-6家族成员的持续高表达。 虽然IL-6相关的细胞因子通常被认为是促炎性的，但最近的结果表明，它们（和下游转录因子Stat 3）对滑膜成纤维细胞和可能的巨噬细胞具有抗炎作用。 一个主要的思想流派认为，促炎因子和抗炎因子之间的平衡决定了疾病的进展，并且炎症去激活阶段的缺陷在RA的发病机制中起着关键作用。 一个重要的问题是，为什么大量表达的抗炎细胞因子并没有导致RA炎症的解决？ 我们已经探讨了IL-10和IL-6相关细胞因子的抗炎作用可能在RA滑膜中的信号转导水平被阻断的可能性。我们已经发现，IL-1，TNF α，和H2 O2抑制IL-6和IL-10活化的Stat 3 DNA结合和酪氨酸磷酸化的机制，似乎依赖于丝裂原活化蛋白激酶（MAPK）。 抑制Stat 3与抑制具有抗炎功能的IL-6诱导型基因的表达相关。 我们推测，滑膜炎期间存在的炎症因子对IL-6和IL-10信号传导和Stat 3活性的抑制通过阻断滑膜炎症的去活化而促成发病机制。 我们建议描绘炎症/MAPK和IL-6/IL-10 Jak-STAT信号通路在滑膜成纤维细胞之间的潜在串扰的机制，并调查这种串扰在RA发病机制的背景下的功能后果。 更好地理解阻断抗炎细胞因子作用的机制将有助于设计新的治疗方法，以改变细胞因子活性的平衡，从而限制炎症和疾病的进展。 我们的具体目标是：（1）鉴定炎性细胞因子IL-1和TNF α以及ROI抑制RA滑膜成纤维细胞中IL-6相关细胞因子和IL-10对Stat 3的活化的分子机制。 (2)确定哪些MAPK在RA滑膜成纤维细胞中抑制IL-6和IL-10信号传导中起重要作用。 (3)表征炎症因子对滑膜成纤维细胞表型的IL-6和IL-10信号转导的调节的功能后果。