Mechanisms of Liver Inflammation

描述（由申请人提供）：我的长期职业目标是明确非酒精性脂肪性肝炎中肝脏炎症的机制。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分支在NASH中巨噬细胞生物学调节中的双重作用。在初步实验中，我们观察到巨噬细胞在棕榈酸（PA）处理后被激活；我们把这种现象称为脂质活化。脂质活化的巨噬细胞经历内质网应激和细胞死亡，称为脂质凋亡。我们在NASH小鼠模型中观察到巨噬细胞积累和PA水平升高。我们的初步观察得出了一个中心假设，即UPR调节肝巨噬细胞中的脂肪激活或脂肪凋亡，从而分别引发或减轻脂肪性肝炎的炎症。因此，本建议的目标是了解：i) UPR的肌醇要求蛋白-1 α （IRE1¿）/ 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¿），增强巨噬细胞活化和细胞因子分泌，从而增加肝脏中的促炎环境；ii) UPR的CHOP分支如何通过降低抗凋亡蛋白Mcl-1和增加促凋亡蛋白Bim来促进巨噬细胞凋亡，从而增加肝脏的抗炎环境。拟议的实验将分别采用脂肪毒性和NASH的互补体外和体内模型；以及化学、药理学、分子和遗传学方法来解决特定的目的，以验证以下假设：i) UPR通过IRE1¿/XBP-1信号传导决定巨噬细胞的招募和激活，ii) CHOP通过内质网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，申请人已经成为巨噬细胞分离，细胞因子分泌分析，转录调节和IRE1或CHOP条件缺失的啮齿动物体内模型的熟练者。通过K08指导临床科学家研究职业发展奖的资助，申请人将继续在巨噬细胞生物学和先天免疫学方面进行额外的培训，以发展这些肝脏炎症关键调节因子的专业知识。申请人已经建立了一个网络，由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. Kaufman博士作为普遍定期审议的合作者。我们的研究结果将为巨噬细胞脂肪激活和脂肪凋亡的调节机制提供深入的见解，从而确定可以通过治疗干预靶向的潜在分子。

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.