Adipsin in NASH

项目摘要 肥胖症的流行带来了多种伴随的代谢合并症，包括非酒精性脂肪酸 肝病（NAFLD）。NAFLD现在是慢性肝病的主要原因， 在某些人群中为30%，但实际上可能被认为是非酒精性脂肪性肝炎的“疾病前”状态 （NASH）和相关的肝纤维化。NASH没有批准的药物治疗，因此是增长最快的 肝移植的原因随着肥胖相关NASH的患病率持续上升， 由于移植仍然有限，这种未满足的需求变得更加迫切。 载脂肝细胞和非实质细胞（NPC）（包括肝细胞）之间的细胞间串扰 星状细胞（HSC），确定肥胖诱导的肝脏病理学。为了确定介导肝细胞- 为了研究NPC串扰，我们在从喂食NASH激发的小鼠中分离的肝细胞中进行了转录组学分析。 饮食.当与正常的普通饲料喂养的小鼠相比时，我们发现Cfd（补体 因子d），其编码Adipsin，Adipsin是一种被认为在脂肪细胞中唯一产生的分泌蛋白，其介导 补体因子C3裂解。我们首先在其他三种饮食NASH小鼠模型中证实了这些数据， 以及NASH患者的肝活检，所有这些都显示肝脏（但不是脂肪）Adipsin增加 在NASH。这些强有力的相关性促使我们测试Adipsin介导NASH表型的潜力。第一、 由于Adipsin将补体因子C3切割成两种生物活性物质-C3 a，其结合靶细胞上的C3 aR 1， 和驱动补体旁路途径激活的C3 b-我们分析了喂食NASH饮食的C3敲除小鼠， 其显示出比对照组更低的纤维化。接下来，我们用病毒载体转导喂食NASH饲料的野生型小鼠 编码Cfd的shRNA，其表型模拟C3敲除动物中观察到的较低的纤维化，在预防和治疗中， 治疗策略。因此，重组C3 a的应用增加了体外HSC的活性。这些结果 表明异常肝Adipsin在NASH中起致病作用，我们将在本申请目的1中对此进行测试， 包括研究Adipsin衍生的C3 a是否直接作用于HSC C3 aR 1以驱动肝纤维化。在Aim中 2、研究NASH肝脏Adipsin异常的机制。初步数据显示， 在小鼠和人NASH中诱导主要脂肪形成因子PPARγ2。这些数据促使 假设在NASH中，PPARγ2介导的肝细胞脂肪形成重编程是必要的， 足以驱动肥胖肝脏中的Cfd表达。实现此应用程序的目标将确定机械 异常Adipsin表达和由此产生的肝脏病理学的决定因素，并可能导致发展 Adipsin或C3 aR 1抑制剂治疗NASH诱导的纤维化。

Project Abstract The obesity pandemic brings with it multiple attendant metabolic comorbidities, including Non-Alcoholic Fatty Liver Disease (NAFLD). NAFLD is now the leading cause for chronic liver disease, with prevalence approaching 30% in certain populations, but may in fact be considered a “pre-disease” state for Non-Alcoholic Steatohepatitis (NASH) and associated liver fibrosis. NASH has no approved pharmacotherapy, and is thus the fastest-growing reason for liver transplantation. As the prevalence of obesity-related NASH continues to rise, and available livers for transplantation remain limiting, this unmet need grows more urgent. Intercellular crosstalk between lipid-laden hepatocytes and non-parenchymal cells (NPCs), including hepatic stellate cells (HSC), determine obesity-induced liver pathology. To determine signals that mediate hepatocyte- NPC crosstalk, we performed transcriptomic analysis in hepatocytes isolated from mice fed a NASH-provoking diet. When compared to normal chow-fed mice, we found significantly increased expression of Cfd (Complement factor d), which encodes Adipsin, a secreted protein thought uniquely produced in adipocytes that mediates complement factor C3 cleavage. We first confirmed these data in three other dietary NASH mouse models, as well as in liver biopsies from patients with NASH, all of which revealed increased liver (but not adipose) Adipsin in NASH. These robust correlations prompted us to test potential of Adipsin to mediate NASH phenotypes. First, as Adipsin cleaves complement factor C3 to two bioactive species – C3a, which binds C3aR1 on target cells, and C3b that drives alternative complement pathway activation – we analyzed C3 knockout mice fed NASH diet, which showed lower fibrosis than controls. Next, we transduced NASH diet-fed wildtype mice with a viral vector encoding shRNA to Cfd, which phenocopied lower fibrosis seen in C3 knockout animals, in both prevention and treatment strategies. Consistently, application of recombinant C3a increased HSC activity in vitro. These results suggest that aberrant liver Adipsin plays a pathogenic role in NASH, which we will test in Aim 1 of this application, including studies to test whether Adipsin-derived C3a acts directly on HSC C3aR1 to drive liver fibrosis. In Aim 2, we study mechanistic determinants of aberrant liver Adipsin in NASH. Preliminary data revealed a striking induction of the master adipogenic factor PPARγ2 in mouse and human NASH. These data prompt the hypothesis that a PPARγ2-mediated adipogenic reprogramming of hepatocytes in NASH is necessary and sufficient to drive Cfd expression in the obese liver. Achieving the goals of this application will identify mechanistic determinants of aberrant Adipsin expression and resultant liver pathology, and potentially lead to development of Adipsin or C3aR1 inhibitors for NASH-induced fibrosis.