Adipsin in NASH

项目摘要 肥胖症的流行带来了多种伴随而来的代谢性共病，包括非酒精脂肪 肝病(NAFLD)。非酒精性脂肪肝现在是慢性肝病的主要原因，患病率接近 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没有被批准的药物疗法，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，以及可用的肝脏 由于移植仍然有限，这一未得到满足的需求变得更加紧迫。 高脂肝细胞与非实质细胞(包括肝脏)之间的细胞间串扰 星状细胞(HSC)，决定肥胖诱导的肝脏病理。为了确定调节肝细胞的信号- NPC串音，我们对喂食Nash刺激的小鼠的肝细胞进行了转录转录分析 节食。与正常喂养的小鼠相比，我们发现CFD(补体)的表达显著增加 D)因子，它编码脂肪蛋白，一种被认为是在脂肪细胞中独特产生的分泌蛋白，它介导 补体因子C3裂解。我们首先在其他三个饮食Nash小鼠模型中证实了这些数据， 在NASH患者的肝脏活检中也是如此，所有这些都显示肝脏(但不是脂肪)脂肪增加。 在纳什。这些强大的相关性促使我们测试Adipsin调节NASH表型的潜力。第一, 当Adipsin将补体因子C3裂解成两个生物活性物种-C3a时，C3a与靶细胞上的C3aR1结合， 和驱动替代补体途径激活的C3b-我们分析了喂食Nash饮食的C3基因敲除小鼠， 显示出比对照组更低的纤维化。接下来，我们用病毒载体将纳什饮食喂养的野生型小鼠转化为 将shRNA编码到CFD，在预防和治疗中都能降低C3基因敲除动物中出现的较低的纤维化 治疗策略。一致地，应用重组C3a可提高HSC的体外活性。这些结果 提示异常的肝脏Adipsin在NASH中起致病作用，我们将在本申请的目标1中进行测试， 包括测试Adipsin衍生的C3a是否直接作用于HSC C3aR1以推动肝纤维化的研究。在AIM 2、研究NASH患者肝脏Adipsin异常的机制决定因素。初步数据显示， 在小鼠和人NASH中诱导主要成脂因子PPARγ2。这些数据提示 假设PPARγ2介导的NASH肝细胞成脂重编程是必要的，并且 足以在肥胖的肝脏中驱动CFD表达。实现此应用程序的目标将确定机械性 Adipsin异常表达的决定因素和由此导致的肝脏病理，并可能导致发展 Adipsin或C3aR1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.