NLR Regulation of Gastrointestinal Inflammation and Tumorigenesis

描述（申请人提供）：结直肠癌是溃疡性结肠炎和其他炎症性肠病（IBDs）患者的严重医学并发症。改变炎症激活的信号级联反应与结肠炎相关结直肠癌（CAC）的发展具有特定的相关性，因为炎症调节失调已被发现与许多类型的癌症和炎症性疾病有关。我们的实验室和其他研究人员最近对NLR （NBD-LRR）蛋白家族进行了表征，这些蛋白家族已被证明是对微生物和环境应激源的先天免疫反应的重要介质。NLR家族成员的一个子集已被证明可以形成多蛋白复合物，被定义为炎症小体，这可以通过参与形成的特定NLR进一步表征。NLR炎性小体以特定的细胞类型和刺激方式将IL-12和IL- 18加工成成熟的细胞因子。这些促炎细胞因子与ibd和癌症有关。除了炎性小体形成nlr外，第二亚群nlr已被证明通过调节NF-:B信号传导作为炎症的负调节因子。NF-:B信号的失调是肠道炎症和肿瘤发生的关键因素。目的：我们的工作假设提出，炎性小体相关NLR NLRP3和抗炎性NLR NLRP12都通过调节先天免疫细胞中的NF-:B信号传导来保护宿主免受溃疡性结肠炎和结肠炎相关癌症的侵袭。然而，NLRP1炎性小体在基质细胞或癌细胞中通过独立于NLRP3蛋白的机制介导炎症和肿瘤发生。具体目的1：研究炎性小体成分Pycard、Caspase-1和NLRP1在EC和CAC发展中的作用。具体目标2：完善NLRP3介导其对EC和CAC生理作用的机制。特异性目的3：通过NLRP12抑制非典型NF-:B信号传导的能力，评估NLRP12在CAC期间作为肿瘤发生负调节因子的能力。研究设计：我们将利用缺乏特异性nlr或炎性小体成分的转基因小鼠来评估炎症性肠病和癌症模型的功能。Aim 1将检验在EC和CAC期间Pycard和Caspase-1介导的衰减不能归因于NLRP3的假设，这提示存在另一种NLR炎性体。在这里，我们将测试NLRP1炎症小体的成分作为潜在的候选者。目的2将验证在EC和CAC期间NLRP3衰减与IL-12和IL-18抑制相关的假设，通过直接或间接调节典型NF-:B活性。目的3将验证NLRP12作为非典型NF-:B信号的负调节因子，在EC和CAC期间减轻炎症并保护宿主的假设。

DESCRIPTION (provided by applicant): Colorectal cancer is a serious medical complication for individuals suffering from ulcerative colitis and other inflammatory bowel diseases (IBDs). Signaling cascades which alter inflammatory activation are of specific relevance to the development of Colitis-associated Colorectal Cancer (CAC), as dysregulation of inflammation has been found to be associated with many types of cancers and inflammatory diseases. Our lab and others have recently characterized the NLR (NBD-LRR) family of proteins, which have been proven to be essential mediators of innate immune responses to microbes and environmental stressors. One subset of NLR family members have been shown to form multiprotein complexes, defined as inflammasomes, which can be further characterized by the specific NLR involved in formation. NLR inflammasomes function, in a cell type and stimuli specific manner, to process IL-12 and IL- 18 into mature cytokines. These proinflammatory cytokines have been implicated in IBDs and cancer. In addition to the inflammasome forming NLRs, a second sub-group of NLRs have been shown to function as negative regulators of inflammation through the modulation of NF-:B signaling. Dysregulation of NF-:B signaling is a critical component in the pathogenesis of inflammation and tumorigenesis in the gut. OBJECTIVES: Our working hypothesis proposes that the inflammasome associated NLR, NLRP3, and the anti-inflammatory NLR, NLRP12, both function to protect the host from ulcerative colitis and colitis associated cancer through the modulation of NF-:B signaling in innate immune cells. However, the NLRP1 inflammasome functions in either stromal or cancer cells to mediate inflammation and tumorigenesis through a mechanism that is independent of the NLRP3 protein. SPECIFIC AIM 1: Examine the contribution of the inflammasome components Pycard, Caspase-1 and NLRP1 in the development of EC and CAC. SPECIFIC AIM 2: Refine the mechanisms by which NLRP3 mediates its physiological effects on EC and CAC. SPECIFIC AIM 3: Evaluate the ability of NLRP12 to function as a negative regulator of tumorigenesis during CAC through its ability to suppress non-canonical NF-:B signaling. STUDY DESIGN: We will utilize genetically manipulated mice lacking specific NLRs or inflammasome components to evaluate function in models of inflammatory bowel disease and cancer. Aim 1 will test the hypothesis that the attenuation mediated by Pycard and Caspase-1 during EC and CAC cannot be attributed to NLRP3, which suggests another NLR inflammasome. Here, we will test the components of the NLRP1 inflammasome as a potential candidate. Aim 2 will test the hypothesis that NLRP3 attenuation during EC and CAC is associated with the suppression of IL-12 and IL-18 through the modulation, either direct or indirect, of canonical NF-:B activity. Aim 3 will test the hypothesis that NLRP12 functions as a negative regulator of non-canonical NF-:B signaling to attenuate inflammation and protect the host during EC and CAC.