Novel anti-fibrotic mechanisms in chemical-induced liver injury

 描述（由申请人提供）：肝纤维化是与外源性暴露相关的许多肝脏疾病的破坏性结果，每年约有100万人死于肝功能衰竭和某些癌症。肝纤维化患者最 可能受益于旨在最大化内源性抗纤维化途径活性的疗法，例如自然杀伤（NK）细胞活化，以延迟肝衰竭的发作。肝中凝血级联反应活性的增加和可溶性纤维蛋白原向不溶性纤维蛋白聚合物的转化是人类肝纤维化和小鼠实验性外源性诱导的肝纤维化的显著特征。虽然经常被认为是病理性的，但组织中 纤维蛋白沉积与增加的纤维化变化并不同义（即，胶原沉积）。事实上，纤维蛋白聚合物沉积在肝纤维化发病机制中的确切作用还很不清楚。我们强有力的初步分析支持了纤维蛋白聚合物对肝脏纤维化发展具有抑制作用的新概念。确定纤维蛋白聚合物在肝纤维化中的确切作用是至关重要的，因为这可以揭示纤维蛋白聚合物作为治疗肝纤维化的假定治疗靶点的特定功能。我们强有力的初步研究表明，纤维蛋白聚合物通过结合特定的细胞整合素来抑制外源性物质诱导的小鼠肝纤维化。这些研究的中心假设是纤维蛋白聚合物通过使整合素α M β 2参与驻留的肝NK细胞以增强其抗纤维化介质的表达来抑制肝纤维化。我们的方法包括表达具有特定功能突变的纤维蛋白原蛋白质的遗传修饰小鼠，研究纤维蛋白体外细胞活化的独特原代NK细胞培养系统，以及变构增强aM β 2依赖性细胞与纤维蛋白聚合物粘附的新型小分子。研究小组由中毒性肝损伤和纤维化、凝血和纤维蛋白原生化/功能以及新型小鼠模型方面的专家组成。具体而言，在我们提出的研究中，我们将：（目的1）确定纤维蛋白抑制实验性肝纤维化的机制;（目的2）确定纤维蛋白体外增强NK细胞活化的机制;（目的3）确定纤维蛋白-NK细胞轴对实验性肝纤维化的贡献。所获得的见解将大大促进 目前对肝纤维化凝血机制的理解，并强调了假定的靶点和新的 抑制肝纤维化的治疗策略。潜在的策略可能包括靶向纤维蛋白的特定非止血功能的药物的基于机制的翻译，其可以减少纤维化而不同时诱导出血风险。

 DESCRIPTION (provided by applicant): Liver fibrosis is a devastating outcome of numerous liver diseases associated with xenobiotic exposure, and accounts for approximately one million deaths annually owing to liver failure and certain cancers. Patients with liver fibrosis would most likely benefit from therapies aimed at maximizing activity of endogenous anti-fibrotic pathways, such as natural killer (NK) cell activation, in order to delay the onset of liver failure. Increase activity of the blood coagulation cascade and conversion of soluble fibrinogen to insoluble fibrin polymers in liver are prominent features of liver fibrosis in humans and experimental xenobiotic-induced liver fibrosis in mice. Although frequently implicated as pathologic, an increase in tissue fibrin deposition is not synonymous with increasing fibrotic changes (i.e., collagen deposition). Indeed, the exact role of fibrin polymer deposition in the pathogenesis of liver fibrosis is largel unknown. Our strong preliminary analysis supports the novel concept that fibrin polymer has an inhibitory effect on fibrosis development in the liver. Identifying the precise role of fibrin polyers in liver fibrosis is critical, because this could reveal specific functions of fibrin polymers as putative therapeutic targets to treat liver fibrosis. Our strong preliminary studies suggest that fibrin polymers inhibit xenobiotic-induced liver fibrosis in mice by engaging specific cellular integrin's. The central hypothesis framing these studies is that fibrin polymers inhibit liver fibrosis by engaging the integrin aMß2 on resident liver NK cells to enhance their expression of anti-fibrotic mediators. Our approach includes genetically-modified mice expressing fibrinogen proteins with specific functional mutations, a unique primary NK cell culture system to study in vitro cell activation by fibrin, and a novel small molecule that allosterically enhances aMß2-dependent cell adhesion to fibrin polymers. The investigative team comprises experts in toxic liver injury and fibrosis, coagulation and fibrinogen biochemistry/function, and novel mouse models. Specifically, in our proposed studies we will: (Aim 1) Determine the mechanism by which fibrin inhibits experimental liver fibrosis; (Aim 2) Determine the mechanisms whereby fibrin enhances NK cell activation in vitro; and (Aim 3) Determine the contribution of the fibrin-NK cell axis to experimental liver fibrosis in vivo. The insights gained will significantly advance the current understanding of coagulation in liver fibrosis and highlight putative targets and novel therapeutic strategies to inhibit liver fibrosis. Potential strategies could include mechanism-based translation of drugs targeting specific non-hemostatic functions of fibrin that could reduce fibrosis without simultaneously inducing a bleeding risk.