Novel Cytokine Regulation of Gut Function and Inflammation

项目摘要 宿主抵抗多种病原体的防御进化的部分特征是两极分化 T辅助细胞（Th）1或Th2细胞因子谱。Th17细胞因子家族的鉴定 提供了一个新的适应性免疫反应的手臂，这对慢性炎症很重要。主机 稳态依赖于个体Th细胞谱系之间的微妙平衡，部分地， 通过细胞因子的相互调节。已知病原体诱导的Th1相对于Th2的上调 细胞因子诱导肠平滑肌和上皮细胞的定型和有时相反的变化 对宿主抵抗力很重要的反应。不平衡，高或低反应性，或缺乏 Th细胞因子谱之间的协调，与肠道功能失调有关，是一种 具有多种肠粘膜炎性病症的特征， 疾病（IBD）。目前，IBD没有治愈方法，也没有现有的药物能在所有患者中诱导缓解。 控制IBD的一种方法是通过增加Th2细胞因子来纠正细胞因子失衡。这可能是 与克罗恩病更相关，克罗恩病由Th1/Th17型占主导地位。IL-25（IL-17E）是一种新发现的 细胞因子和IL-17细胞因子家族的成员。与该家族中的其他细胞因子不同，IL-25促进Th2 同时抑制Th1和Th17细胞因子反应，从而作为炎症的关键调节因子， 肠粘膜参与IL-25促进Th2和/或抑制Th2的能力的细胞类型和机制 Th1/Th17反应，特别是在结肠中，是未知的。关于IL-1的调节信息很少。 25在炎症过程中或其对肠道功能相关变化的贡献。我们的初步数据 显示上皮细胞是IL-25主要来源，也表达IL-25受体IL-17 RA和IL-17 RB 暗示这种细胞因子是粘膜免疫的关键成分。这个项目的核心假设是 上皮来源的IL-25在调节粘膜免疫和屏障功能中起关键作用， 促进Th2介导的免疫和肠道功能的变化。该项目有三个具体目标。 具体目标1将描述线虫感染诱导的表达上调的机制和结果。 结肠上皮细胞中的IL-25。我们假设IL-4/IL-13和IL-14之间存在相互调节， IL-25促进Th2介导的宿主保护性免疫。我们将1）识别细胞群中的细胞群， 产生和/或应答IL-25的结肠以及IL-25/IL-25免疫调节的潜在机制 17RA/IL-17RB在T.研究IL-25/IL-17RA/IL-17RB的直接诱导作用 通过IL-4/IL-13激活STAT6在结肠上皮细胞中的表达; 3）研究IL-25促进Th2 通过巨噬细胞的免疫应答;和4）确定线虫或巨噬细胞对IL-25的直接诱导。 上皮细胞中的产物。特异性目的2将决定IL-25在结肠癌免疫调节中的作用。 功能我们假设IL-25对上皮和平滑肌有直接和间接的作用 Th2保护性免疫的关键功能。我们将1）确定IL-25在 结肠功能的生理和病理生理控制; 2）研究外源性IL-2的依赖性， 25-诱导结肠功能对IL-4、IL-13和STAT6的改变; 3）建立IL-25对结肠功能的直接影响。 结肠上皮通透性;和4）确定IL-25对结肠平滑肌的直接作用 收缩。特异性目的3将确定IL-25在结肠炎症中的作用。我们假设IL-25 是肠道免疫稳态的关键调节剂，IL-25免疫应答的失调在肠道免疫中起着重要作用。 在结肠炎症中起重要作用。我们将1）确定IL-25中的缺陷是否影响 小鼠对结肠炎症的易感性; 2）评估外源性IL-25对结肠炎症过程的影响， TNBS或恶唑酮诱导的结肠炎;和3）研究IL-25在调节先天性免疫中的作用。 通过TLR信号应答。这些研究提供了一种系统的方法来确定IL-25作为关键 结肠中的免疫调节细胞因子。此外，这些研究将确定IL-10对细胞功能的影响。 25以及参与调节IL-25和IL-25受体表达的机制。 （TNBS诱导的）和Th2-（T.鼠诱导的）显性病理。

PROJECT SUMMARY Evolution of host defense to combat a multitude of pathogens is characterized, in part, by polarization towards either the T helper (Th) 1 or Th2 cytokine profile. The identification of theTh17 cytokine family provides a new arm of the adaptive immune response that is important for chronic inflammation. Host homeostasis relies on the delicate balance among the individual Th cell lineages that are controlled, in part, through reciprocal regulation of the cytokines. It is known that pathogen-induced up-regulation of Th1 vs Th2 cytokines induces stereotypic and sometimes opposing changes in gut smooth muscle and epithelial cell responses that are important for host resistance. An imbalance, hyper- or hypo-responsiveness, or lack of coordination among the Th cytokine profiles, is associated with dysregulation of gut function and is a characteristic of a number of mucosal inflammatory conditions of the gut including inflammatory bowel disease (IBD). Currently, there is no cure for IBD and no existing medication induces remission in all patients. One approach to control IBD is to rectify the cytokine imbalance by increasing Th2 cytokines. This may be more relevant to Crohn's disease, which is dominated by Th1/Th17 profile. IL-25 (IL-17E) is a newly-identified cytokine and a member of the IL-17 cytokine family. Unlike other cytokines in this family, IL-25 promotes Th2 while suppress Th1 and Th17, cytokine responses, thereby serving as a key regulator of inflammation in the gut mucosa. The cell types and mechanisms involved in IL-25's ability to promote Th2 and/or suppress Th1/Th17 response, particularly in the colon, are unknown. There is little information on the regulation of IL- 25 during inflammation or its contribution to the associated changes in gut function. Our preliminary data show that epithelial cells are a major source of IL-25 and also express IL-25 receptors IL-17RA and IL-17RB implicating this cytokine as a key component in mucosal immunity. The central hypothesis of this project is that epithelial derived IL-25 plays a key role in modulating mucosal immunity and barrier function as well as promoting the Th2-mediated changes in immune and gut function. There are 3 specific aims in this project. Specific Aim 1 will characterize the mechanism and outcome of nematode infection-induced up-regulation of IL-25 in colonic epithelial cells. We hypothesize that there is a reciprocal regulation between IL-4/IL-13 and IL-25 that promotes Th2-mediated host protective immunity. We will 1) identify the cell populations in the colon that produce and/or respond to IL-25 and the underlying mechanism of immune regulation of IL-25/IL- 17RA/IL-17RB in mice during T. muris infection; 2) investigate the direct induction of IL-25/IL-17RA/IL-17RB expression in colonic epithelial cell by IL-4/IL-13 activation of STAT6; 3) investigate IL-25 promoting Th2 immune response via macrophages; and 4) Determine the direct induction of IL-25 by nematode or the product in epithelial cells. Specific Aim 2 will determine the role of IL-25 in the immune regulation of colonic function. We hypothesize that IL-25 has both direct and indirect effects on epithelial and smooth muscle function that are critical to an effective Th2 protective immunity. We will 1) Determine the role of IL-25 in the physiologic and pathophysiologic control of colonic function; 2) Investigate the dependence of exogenous IL- 25-induced alterations in colonic function on IL-4, IL-13, and STAT6; 3) Establish the direct effects of IL-25 on colonic epithelial permeability; and 4) Determine the direct effects of IL-25 on colonic smooth muscle contraction. Specific Aim 3 will determine the role of IL-25 in colonic inflammation. We hypothesize that IL-25 is a critical regulator of intestinal immune homeostasis and dysregulation of IL-25 immune responses plays an important role in colonic inflammation. We will 1) Determine whether a defect in IL-25 affects the susceptibility of mice to colonic inflammation; 2) Assess the effects of exogenous IL-25 on the course of TNBS-or oxazolone-induced colitis; and 3) Investigate the role of IL-25 in modulating the innate immune response through TLR signaling. These studies provide a systematic approach to establish IL-25 as a key immuno- regulatory cytokine in the colon. In addition, these studies will establish the functional impact of IL- 25 as well as the mechanisms involved in regulation of IL-25 and IL-25 receptor expression during Th1- (TNBS-induced) and Th2- (T. muris-induced) dominant pathologies.