Mechanisms of Liver Inflammation

描述（由申请人提供）：我的长期职业目标是确定非酒精性脂肪性肝炎肝脏炎症的机制。目前的建议集中在内质网（ER）应激激活未折叠蛋白反应（UPR）的三个已知分支中的两个在NASH巨噬细胞生物学调节中的二分作用。在初步实验中，我们观察到，巨噬细胞被激活后，棕榈酸（PA）的治疗，我们称这种现象的脂活化。脂活化的巨噬细胞经历ER应激，也经历细胞死亡，称为脂凋亡。我们已经观察到巨噬细胞在NASH小鼠模型中的积累沿着PA水平升高。我们的初步观察导致了一个中心假设，即UPR调节肝脏巨噬细胞中的脂活化或脂凋亡，从而分别引发或减轻脂肪性肝炎中的炎症。因此，本提案的目标是了解：i）UPR的肌醇需要蛋白-1 α（IRE 1 <$$>）/ X-box结合蛋白（XBP-1）分支如何通过靶向细胞因子单核细胞趋化蛋白-1（MCP-1）和白细胞介素-1 β（IL-1 <$1）增强巨噬细胞活化和细胞因子分泌来增加肝脏中的促炎环境。和ii）UPR的CHOP分支如何通过减少抗凋亡蛋白Mcl-1和增加促凋亡蛋白Bim来增强巨噬细胞凋亡，从而增加肝脏中的微环境。所提出的实验将分别采用脂毒性和NASH的体外和体内互补模型;以及化学、药理学、分子和遗传学方法来解决特定目标，以测试以下假设：i）UPR通过IRE 1/XBP-1信号传导决定巨噬细胞募集和激活，ii）通过CHOP的ER应激促进巨噬细胞凋亡，以及iii）UPR调节NASH中的肝脏炎症。为了解决这些假设，申请人已经变得擅长巨噬细胞分离、细胞因子分泌测定、转录调节和IRE 1或CHOP条件性缺失的体内啮齿动物模型。通过K 08指导临床科学家研究职业发展奖的资助，申请人将继续进行巨噬细胞生物学和先天免疫学的额外培训，以发展这些肝脏炎症关键调节因子的专业知识。申请人建立了一个网络，其中包括Gregory J. Gores博士作为她的主要导师，Peter J. Wettstein博士作为免疫学合作者，Randal J.考夫曼博士作为普遍定期审议合作者。我们的研究结果将产生机制的见解调节巨噬细胞脂活化和脂凋亡的个别UPR组件，从而确定潜在的分子，可以通过治疗干预措施的目标。

DESCRIPTION (provided by applicant): My long term career objective is to define the mechanisms of liver inflammation in nonalcoholic steatohepatitis. The current proposal focuses on the dichotomous role of two of the three known branches of the endoplasmic reticulum (ER) stress-activated unfolded protein response (UPR) in the regulation of macrophage biology in NASH. In preliminary experiments we have observed that macrophages are activated upon treatment with palmitic acid (PA); we have termed this phenomenon lipoactivation. Lipoactivated macrophages undergo ER stress, and also cell death, termed lipoapoptosis. We have observed macrophage accumulation in a mouse model of NASH along with elevated PA levels. Our preliminary observations have led to the central hypothesis that the UPR regulates either lipoactivation or lipoapoptosis in hepatic macrophages thereby instigating or mitigating inflammation, respectively, in steatohepatitis. Therefore, the goals of this proposal are to understand: i) how the Inositol Requiring Protein-1 alpha (IRE1¿)/ X-box binding protein (XBP-1) branch of the UPR increases the proinflammatory milieu in the liver by enhancing macrophage activation and cytokine secretion via targeting the cytokines monocyte chemotactic protein-1 (MCP-1) and interleukin-1beta (IL-1¿), and ii) how the CHOP branch of the UPR increases the antiinflammatory milieu in the liver by enhancing macrophage apoptosis by decreasing the antiapoptotic protein Mcl-1 and increasing the proapoptotic protein Bim. The proposed experiments will employ complementary in vitro and in vivo models of lipotoxicity and NASH, respectively; and chemical, pharmacological, molecular and genetic approaches to address the specific aims to test the hypotheses that: i) The UPR determines macrophage recruitment and activation via IRE1¿/XBP-1 signalling, ii) ER stress via CHOP promotes macrophage apoptosis, and iii) The UPR regulates hepatic inflammation in NASH. To address these hypotheses the applicant has become adept at macrophage isolation, assays of cytokine secretion, transcriptional regulation, and in vivo rodent models of conditional deletion of IRE1¿ or CHOP. With funding through this K08 Mentored Clinical Scientist Research Career Development Award the applicant will pursue additional training in macrophage biology and Innate Immunology to develop expertise in these key regulators of hepatic inflammation. The applicant has established a network consisting of Dr. Gregory J. Gores as her primary mentor, Dr. Peter J. Wettstein as the Immunology collaborator, and Dr. Randal J. Kaufman as the UPR collaborator. Our results will yield mechanistic insights into regulation of macrophage lipoactivation and lipoapoptosis by individual UPR components, thus identifying potential molecules that can be targeted by therapeutic interventions.