Regulation of Intestinal inflammation by TLR4-mediated signals

TLR4 介导的信号调节肠道炎症

基本信息

批准号：
8102070
负责人：
CATHRYN R NAGLER
金额：
$ 19.31万
依托单位：
UNIVERSITY OF CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-01 至 2012-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8102070
关键词：
Adoptive Transfer Adult Animal Housing Antigen-Presenting Cells Apoptosis Apoptotic Bacteria Bone Marrow CD4 Positive T Lymphocytes Cell Differentiation process Cells Chronic Colitis Data Dendritic Cells Development Disease Effector Cell Epithelial Epithelial Cell Proliferation Epithelial Cells Exhibits Failure Helicobacter Helicobacter hepaticus Immune Immunotherapeutic agent In Vitro Incidence Individual Infection Inflammation Inflammatory Inflammatory Bowel Diseases Inflammatory Response Inflammatory disease of the intestine Injury Interferons Interleukin-10 Interleukin-17 Intestinal Mucosa Intestines Lamina Propria Lead Maintenance Measures Mediating Memory Modeling Mus Mutation Phagocytosis Phenotype Physiological Population Prevalence Rag1 Mouse Regulation Regulatory T-Lymphocyte Role Severities Signal Transduction Site T-Cell Activation T-Lymphocyte TCR Activation TLR4 gene Time Ursidae Family Work disorder control functional loss in vivo intestinal epithelium macrophage novel prevent public health relevance response

项目摘要

DESCRIPTION (provided by applicant): We and others have recently shown that the time of onset, incidence and severity of colitis is exacerbated in IL-10-/- mice that also bear a mutation in TLR-4. By a mechanism apparently unrelated to its role in innate immune signaling by antigen presenting cells (APC), TLR-4 signaling by CD4+ T cells regulates the response to subsequent TCR activation. CD4+ T cells from TLR-4-/- x IL-10-/- (DKO) mice exhibit enhanced proinflammatory colitiogenic effector responses when measured either directly ex vivo or after adoptive transfer into Rag1-/- recipients. Moreover, Foxp3+ Tregs isolated from TLR-4-/- mice are impaired in their ability to secrete IL-10. TLR-4 signaling in CD4+ T cells therefore enhances Treg function and inhibits inflammatory T effector function; these two roles are likely to synergize to prevent intestinal inflammation in healthy mice. In DKO mice, however, Foxp3+ Tregs accumulate in the inflamed lamina propria (LP), secrete IFN-? and IL-17, and fail to control disease. A role for MyD88 dependent TLR-4 mediated signals in the homeostatic maintenance of the intestinal epithelial barrier is already well established. We found that apoptotic remnants apparently derived from the intestinal epithelium accumulate in the colonic LP of Helicobacter-positive (Hh+) TLR-4-/- mice (in the absence of inflammation) as well as in the inflamed LP of both IL-10-/- and DKO mice. Apoptotic cells were not detectable in the colonic LP of WT C57Bl/6 mice or Helicobacter free (Hh-) TLR-4-/- or DKO mice. How does the absence of TLR-4 mediated signals exacerbate intestinal inflammation in IL-10 deficient mice? Our working hypothesis is that apoptotic epithelial cells accumulate in the colonic LP of Helicobacter-colonized DKO mice and induce an inflammatory Th17 response. IFN-? is also induced in the absence of tonic TLR-4 signaling in CD4+ effector T cells. The apoptosis induced IL-17 response leads to an earlier and increased recruitment of inflammatory cells to the intestines that results ultimately in chronic colitis. In Helicobacter-colonized TLR-4-/- mice this chronic inflammatory response is held in check by the immunoregulatory effects of IL-10. In DKO mice, however, T cell activation is dysregulated in the absence of TLR-4 signaling, potentiating the inflammatory T effector response. Treg function and/or stability is also compromised in DKO mice and the Tregs themselves become pathogenic effector cells. In Aim 1, both in vitro and in vivo approaches will be used to examine whether Helicobacter induced apoptotic epithelial remnants phagocytosed by APC in the colonic LP induce IL-17 producing Foxp3- and Foxp3+ T cells and drive intestinal inflammation in DKO mice. In Aim 2 we will further characterize the putative pathogenic Tregs in the LP of DKO mice and the triggers that destabilize or convert this Treg subset. We will also examine the functional suppressive and/or effector capabilities of these cells. PUBLIC HEALTH RELEVANCE: We will use a novel murine model of spontaneous intestinal inflammation to examine the triggers that lead to the failure of the responses that protect healthy individuals from disease. A clearer understanding of the mechanisms regulating this protection may inform the development of new immunotherapeutic approaches to treat or prevent inflammatory bowel disease (IBD).

描述（由申请人提供）：我们和其他人最近表明，在同样携带 TLR-4 突变的 IL-10-/- 小鼠中，结肠炎的发病时间、发病率和严重程度会加剧。通过一种显然与其在抗原呈递细胞 (APC) 的先天免疫信号传导中的作用无关的机制，CD4+ T 细胞的 TLR-4 信号传导调节对随后 TCR 激活的反应。当直接离体测量或过继转移至 Rag1-/- 受体后测量时，来自 TLR-4-/- x IL-10-/- (DKO) 小鼠的 CD4+ T 细胞表现出增强的促炎性结肠炎效应反应。此外，从 TLR-4-/- 小鼠中分离出的 Foxp3+ Tregs 分泌 IL-10 的能力受损。因此，CD4+ T 细胞中的 TLR-4 信号传导可增强 Treg 功能并抑制炎症 T 效应子功能；这两种作用可能协同作用，预防健康小鼠的肠道炎症。然而，在 DKO 小鼠中，Foxp3+ Tregs 在发炎的固有层 (LP) 中积聚，分泌 IFN-α和IL-17，并且无法控制疾病。 MyD88 依赖性 TLR-4 介导的信号在肠上皮屏障稳态维持中的作用已经得到充分证实。我们发现明显源自肠上皮的凋亡残余物在螺杆菌阳性（Hh+）TLR-4-/-小鼠（在没有炎症的情况下）的结肠LP中以及IL-10-的发炎LP中积累。 /- 和 DKO 小鼠。在 WT C57Bl/6 小鼠或无螺杆菌 (Hh-) TLR-4-/- 或 DKO 小鼠的结肠 LP 中未检测到凋亡细胞。 IL-10 缺陷小鼠中 TLR-4 介导信号的缺失如何加剧肠道炎症？我们的工作假设是，凋亡的上皮细胞在螺杆菌定植的 DKO 小鼠的结肠 LP 中积聚，并诱导炎症性 Th17 反应。干扰素-?在 CD4+ 效应 T 细胞中缺乏补给性 TLR-4 信号传导的情况下也会被诱导。细胞凋亡诱导的 IL-17 反应导致炎症细胞更早且更多地募集到肠道，最终导致慢性结肠炎。在螺杆菌定植的 TLR-4-/- 小鼠中，这种慢性炎症反应受到 IL-10 免疫调节作用的控制。然而，在 DKO 小鼠中，在 TLR-4 信号传导缺失的情况下，T 细胞激活失调，从而增强了炎症 T 效应反应。 DKO 小鼠中 Treg 功能和/或稳定性也受到损害，Treg 本身成为致病效应细胞。在目标 1 中，将使用体外和体内方法来检查结肠 LP 中被 APC 吞噬的螺杆菌诱导的凋亡上皮残余物是否诱导产生 IL-17 的 Foxp3- 和 Foxp3+ T 细胞并驱动 DKO 小鼠肠道炎症。在目标 2 中，我们将进一步描述 DKO 小鼠 LP 中假定的致病性 Tregs 以及破坏该 Treg 子集稳定或转化的触发因素。我们还将检查这些细胞的功能抑制和/或效应能力。公共卫生相关性：我们将使用一种新型的自发性肠道炎症小鼠模型来检查导致保护健康个体免受疾病的反应失败的触发因素。更清楚地了解调节这种保护的机制可能有助于开发新的免疫治疗方法来治疗或预防炎症性肠病（IBD）。