Regulation Of Immune Responses In Humans and in Experime

人类和实验中免疫反应的调节

• 批准号: 7299936
• 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/7299936
• 关键词: Regulation; Immune; Responses; Humans; Experime

Project 1: To investigate the immunopathogenesis of inflammation-associated fibrosis we analyzed the recurrent colitis and late-developing fibrosis occurring in BALB/c mice administered weekly doses of intra-rectal trinitrobenzene sulfonic acid (TNBS). We showed first that in this model an initial Th1 response involving IL-12p70 and IFN-g subsides after three weeks only to evolve into a IL-23/IL-25 response beginning after 4-5 weeks. This evolution is followed by gradually increasing production of IL-17 and cytokines ordinarily seen in a Th2 response, particularly IL-13, that reaches a plateau at 8-9 weeks. In vitro stimulation studies suggest that this IL-13 production is dependent on IL-23 and IL-25, but not on IL-12p70. We then show that IL-13 production results in the induction of a novel IL-13 receptor formerly thought to function only as a decoy receptor, IL-13Ra2, and this receptor is critical to the production of TGF-b1 and the onset of fibrosis. Thus, if IL-13 is blocked by soluble IL-13Ra2-Fc, TGF-b1 is not produced and/or fibrosis does not occur. These studies show that in recurrent TNBS colitis, fibrosis is dependent on the development of an IL-13 response that acts through a novel cell-surface-expressed IL-13 receptor to induce TGF-b1. A similar mechanism may obtain in certain forms of human IBD. Project 2: To explore the function of Stat4 in Th1 mucosal inflammation we studied mice with reduced (but not absent) Stat4 expression due to the presence of a doxycycline-regulated Stat4 anti-sense transgene or intra-rectal administration of a Stat4 anti-sense plasmid. Initially we showed that SJL/J mice treated with doxycycline and expressing the transgene do not develop TNBS-colitis, a Th1 mucosal inflammation. This seemed due to a cell traffic problem since these mice exhibited accumulation of potential effector cells in the spleen (rather than in the intestine) that displayed decreased Th1-chemokine receptor expression. To further examine this possibility we transferred spleen cells from mice administered TNBS with or without doxycyline to recipients given low doses of TNBS; we found that transfer of cells from mice administered doxycycline did not result in colitis whereas those administered doxycline did, even though both recipient post-transfer spleens contained potential Th1 effector T cells. Finally, we showed that mice administered a plasmid expressing the Stat4 anti-sense construct also displayed decreased TNBS-colitis and reduced chemokine receptor expression. These studies demonstrate that Stat4 down-regulation leads to failure of effector cell traffic to the lamina propria and such down-regulation is a viable approach to the treatment of Crohn?s disease.

项目一： 为了研究炎症相关纤维化的免疫发病机制，我们分析了每周直肠内给予三硝基苯磺酸（TNBS）的BALB/c小鼠中发生的复发性结肠炎和晚期纤维化。我们首先表明，在该模型中，涉及IL-12p70和IFN-g的初始Th1应答在3周后消退，仅在4 - 5周后开始演变为IL-23/IL-25应答。这种演变之后是IL-17和通常在Th2应答中看到的细胞因子（特别是IL-13）的产生逐渐增加，其在8 - 9周达到平台期。体外刺激研究表明，这种IL-13的产生依赖于IL-23和IL-25，但不依赖于IL-12p70。然后，我们表明，IL-13的产生导致诱导一种新的IL-13受体，以前认为其仅作为诱饵受体IL-13Ra 2发挥作用，这种受体对TGF-β 1的产生和纤维化的发生至关重要。因此，如果IL-13被可溶性IL-13 Ra 2-Fc阻断，则不产生TGF-β 1和/或不发生纤维化。这些研究表明，在复发性TNBS结肠炎中，纤维化依赖于IL-13反应的发展，该反应通过新的细胞表面表达的IL-13受体来诱导TGF-β 1。类似的机制可以在某些形式的人IBD中获得。 项目二： 为了探索Stat4在Th1粘膜炎症中的功能，我们研究了由于存在强力霉素调节的Stat4反义转基因或直肠内施用Stat4反义质粒而导致Stat4表达减少（但并非缺失）的小鼠。最初，我们发现用强力霉素治疗并表达转基因的SJL/J小鼠不会发生TNBS-结肠炎，一种Th1粘膜炎症。这似乎是由于细胞运输问题，因为这些小鼠在脾脏（而不是肠道）中显示出潜在效应细胞的积累，这些效应细胞显示出Th1-趋化因子受体表达降低。为了进一步研究这种可能性，我们将给予TNBS加或不加多西环素的小鼠的脾细胞转移到给予低剂量TNBS的受体中;我们发现，给予多西环素的小鼠的细胞转移不会导致结肠炎，而给予多西环素的小鼠则会导致结肠炎，尽管两种受体转移后的脾都含有潜在的Th1效应T细胞。最后，我们发现给予表达Stat4反义构建体的质粒的小鼠也显示出TNBS结肠炎减少和趋化因子受体表达减少。这些研究表明，Stat4下调导致效应细胞交通的固有层失败，这种下调是一种可行的方法来治疗克罗恩病？的疾病。