Immunoregulation In Humans And Non-human Primates

人类和非人类灵长类动物的免疫调节

• 批准号: 6985590
• 负责人: WARREN STROBER
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6985590
• 关键词: biological signal transduction; cellular pathology; chemical structure function; epithelium; fibrosis; human subject; human tissue; immunoregulation; inhibitor /antagonist; interleukin 12; interleukin 13; intermolecular interaction; laboratory mouse; lung disorder; macrophage; molecular pathology; natural killer cells; tissue /cell culture; transforming growth factors; ulcerative colitis

In studies described in the previous annual report, we showed that ulcerative colitis is associated with the presence of "non-classical" NKT cells that produce IL-13. The latter can then act as an autocrine factor that induces the NKT cells to manifest greatly increased cytotoxicity for epithelial cells. In addition, in collaborative work with investigators in Germany, we have also shown that the IL-13 induces decreases in the barrier function of the epithelium, thereby exposing the lamina propria to commensal organisms and antigens that induce inflammatory responses. Thus, it is very probable that these IL-13 effects are key factors in the causation of ulcers in ulcerative colitis. In the present period we conducted studies to investigate the mechanisms of IL-13 signaling wiht the view of understanding how such signaling affects NKT cell and epithelial cell function. In addition, we wished to explore how IL-12 induces TGF-beta and TGF-beta-mediated fibrosis, which are also accompaniments of ulcerative colitis. In initial studies we showed that activation of a TGF-beta-luciferase reporter gene in THP-1 (macrophage) cells could be obtained by stimulation with IL-13 and TNF-alpha, but not with either cytokine alone. In addition, we showed that induction of IL-13Ralpha2 required both cytokines signaling via STAT6 and NF-kappaB; however, once IL-13Ralpha2 expression is achieved, IL-13 can activate the TGF-beta1 reporter gene alone (in the absence of TNF-alpha) in a STAT6 independent fashion. For this process, the full length IL-13Ralpha2 molecule is necessary, as the deletion of the cytoplasmic tail abolishes TGF-beta1 reporter gene activation. Applying the above data to in vivo studies of IL-13 signaling, we found that blockade of TNF-alpha signaling by administration of TNF-alphaR-Fc (etanercept) in oxazalone-colitis and in bleomycin-induced lung fibrosis led to marked downregulation of IL-13Ralpha2 expression, TGF-beta1 production and collagen deposition. In addition, blockade of TNF-alpha signaling in oxazalone colitis, a mouse model of ulcerative colitis (again with etanercept) led to loss of IL-13Ralpha2 expression and vastly decreased TGF-beta1 production. In addition, it led to extension of the colitis to the proximal colon where it normally does not occur because of high TGF-beta1 production in this area. These studies indicate that stimulation of TGF-beta1 (and induction of fibrosis) by IL-13 and TNF-alpha is a two-stage process involving: 1) induction of the IL-13Ralpha2 and 2) induction of TGF-beta1 via IL-13Ralpha2 signaling. Thus, the IL-13Ralpha2 proves to be a signaling receptor (not just a decoy) that enables facilitated IL-13 signaling leading to TGF-beta1 production and fibrosis. As such it paradoxically serves as a therapeutic target for the prevention of tissue fibrosis during chronic inflammation. In addition, they show that a model of ulcerative colitis can be influenced by an agent (etanercept) that modulates the expression of the IL-13Ralpha2.

在前一份年度报告中描述的研究中，我们表明溃疡性结肠炎与产生IL-13的“非经典”NKT细胞的存在有关。后者可以作为一种自分泌因子，诱导NKT细胞对上皮细胞表现出极大的细胞毒性。此外，在与德国研究人员的合作中，我们还表明，IL-13诱导上皮屏障功能下降，从而使固有层暴露于共生生物和抗原，从而诱导炎症反应。因此，这些IL-13的作用很可能是溃疡性结肠炎溃疡发生的关键因素。 本研究旨在了解IL-13信号对NKT细胞和上皮细胞功能的影响，探讨IL-13信号传导机制。此外，我们希望探索IL-12如何诱导转化生长因子-β和转化生长因子-β介导的纤维化，这也是溃疡性结肠炎的伴发因素。在最初的研究中，我们发现，在THP-1(巨噬细胞)细胞中，转化生长因子-β-荧光素酶报告基因的激活可以通过IL-13和肿瘤坏死因子-α的刺激而获得，但不能单独使用这两种细胞因子。此外，我们还发现，IL-13Ralpha2的诱导需要通过STAT6和NF-kappaB两种细胞因子的信号转导；然而，一旦IL-13Ralpha2获得表达，IL-13就可以以STAT6独立的方式单独激活转化生长因子-β1报告基因(在没有肿瘤坏死因子-α的情况下)。在这个过程中，全长的IL-13Ralpha2分子是必需的，因为细胞质尾巴的缺失取消了转化生长因子-β1报告基因的激活。将上述数据应用于IL-13信号转导的体内研究，我们发现，在恶唑酮结肠炎和博莱霉素诱导的肺纤维化中，应用TNF-αR-Fc(依那西普)阻断TNF-α信号转导，可显著下调IL-13Ralpha2的表达、转化生长因子-β1的产生和胶原沉积。此外，阻断恶唑酮结肠炎(溃疡性结肠炎的小鼠模型)中的肿瘤坏死因子-α信号导致IL-13Ralpha2的表达丢失，并极大地减少转化生长因子-β1的产生。此外，由于转化生长因子-β1在这一区域的大量产生，导致结肠炎延伸到正常情况下不会发生的近端结肠。 这些研究表明，IL-13和TNF-α对转化生长因子-β1的刺激(和诱导纤维化)是一个两个阶段的过程：1)诱导IL-13α2；2)通过IL-13α2信号诱导转化生长因子-β1。因此，IL-13Ralpha2被证明是一种信号受体(而不仅仅是诱饵)，能够促进IL-13信号转导导致转化生长因子-β1的产生和纤维化。因此，它自相矛盾地成为预防慢性炎症期间组织纤维化的治疗靶点。此外，他们还表明，溃疡性结肠炎的模型可以受到一种调节IL-13Ralpha2表达的药物(依那西普)的影响。