The Role of Matrix Rigidity and Hepatocyte Mechanotransduction in Fibrotic Liver Disease

项目总结 肝纤维化，最终是肝硬变，是慢性肝病的最终共同途径，由任何 病因学。在美国，肝硬变导致的肝功能衰竭是第12大疾病致死原因。 除了肝移植，目前还没有其他有效的治疗方法。肝硬变的一个特征是 肝细胞外基质变得僵硬，但僵硬的微环境如何导致肝细胞 功能障碍还没有完全被理解。我们提出的研究解决了这一知识差距，并 旨在提供将导致在肝硬变治疗方面取得切实进展的数据，这可能包括 1)在进行性肝纤维化患者中维持足够肝功能的新疗法的发展 疾病，2)临床预后模型，预测哪些肝纤维化消退的患者可能会恢复足够的 肝功能，以及3)用于组织替代治疗的高功能组织工程肝构建 终末期肝功能不全患者。我们的初步研究表明，肝细胞 对细胞外基质的机械信号做出反应，以适应纤维化肝脏的硬度，并且 诱导的下游信号通路(即机械转导)直接抑制肝细胞的功能。vbl.使用 多学科交叉模式的方法，我们建议进一步描绘一个僵化的机制如何 微环境导致肝细胞功能障碍及其临床适用性。这些科学目标将 首先，通过确定将机械信号转化为细胞内信号的关键分子角色来实现 使用组织特异性和基因工程小鼠模型抑制肝细胞功能的信号 时间诱导的关键机械转导分子的表达。随后，我们建议核实 通过在微尺度水平表征基质刚性来研究这些分子机制的临床相关性 原子力显微镜结合单细胞测定的正常人和肝硬变患者的肝脏 基因表达分析。最后，我们建议检验微环境之间的关系 刚性和肝细胞功能可能在复杂的组织工程肝脏结构中重现，这些组织工程肝脏结构 由体外三维生物打印产生，并调整到正常或纤维化的人类肝脏的硬度。 这项拟议的研究在概念上是创新的，因为它不是试图从治疗上针对 纤维化的过程，我们的目的是了解肝细胞对纤维化的反应，从而促使新的 侧重于调节肝细胞反应的慢性肝病的治疗和预测方法 对纤维化的刺激。归根结底，导致肝病死亡的是肝功能衰竭，而不是 必然是纤维化本身的过程。这项拟议研究的结果将权威地定义这一角色 说明基质刚性在调节肝细胞功能中的作用，并阐明临床翻译的几条途径。

PROJECT SUMMARY Liver fibrosis, and ultimately cirrhosis, is the final common pathway of chronic liver diseases induced by any etiology. Liver failure due to cirrhosis is the 12th leading cause of death by disease in the United States and there is no effective current treatment other than liver transplantation. One hallmark of liver cirrhosis is that the liver extracellular matrix becomes stiffer, but how the stiffened microenvironment causes hepatocyte dysfunction is not completely understood. Our proposed research addresses this gap in knowledge and is designed to deliver data that will lead to tangible advances in the treatment of liver cirrhosis, which may include development of 1) novel therapies that maintain adequate liver function in patients with progressive fibrotic liver disease, 2) clinical prognostic models that predict which patients with resolving fibrosis may regain sufficient hepatic function, and 3) highly functional tissue-engineered liver constructs for tissue replacement therapy in patients with end-stage liver insufficiency. Our preliminary studies show that hepatocytes are exquisitely responsive to the mechanical cues of extracellular matrix tuned to the stiffness of fibrotic livers, and that the induced downstream signaling pathways (i.e. mechanotransduction) directly inhibit hepatocyte function. Using a multi-disciplinary cross-modality approach, we propose to further delineate the mechanism of how a stiffened microenvironment induces hepatocyte dysfunction and its clinical applicability. These scientific objectives will be achieved first, by determining the key molecular players that translate mechanical cues into intracellular signals that inhibit hepatocyte function using genetically engineered mouse models with tissue-specific and temporally-induced expression of key mechanotransduction molecules. Subsequently, we propose to verify the clinical relevance of these molecular mechanisms by characterizing matrix rigidity at the microscale level in normal and cirrhotic human livers as determined by atomic force microscopy, in conjunction with single-cell gene expression analysis. Finally, we propose to test whether the relationship between microenvironment rigidity and hepatocyte function may be recapitulated in complex tissue-engineered liver constructs that are produced by three-dimensional bioprinting ex vivo and tuned to the stiffness of normal or fibrotic human liver. The proposed research is conceptually innovative because, instead of attempting to therapeutically target the process of fibrosis, we aim to understand the hepatocyte response to fibrosis, thereby prompting new approaches to treat and prognosticate chronic liver disease that focus on modulating the hepatocyte response to the fibrotic stimulus. It is, in the end, liver functional failure that causes death from liver disease, and not necessarily the process of fibrosis in itself. Results from this proposed study will authoritatively define the role of matrix rigidity in modulating hepatocyte function and illuminate several paths toward clinical translation.