Fibrinogen Mechanisms on Perivascular Fibroblast activation after Stroke

瘢痕形成是对中枢神经系统（CNS）损伤和疾病的常见反应，也是阻碍中枢神经系统功能再生的主要障碍。中枢非神经“纤维化”病变核心由限于血管和脑膜壁龛的基质细胞和中枢神经系统相关的巨噬细胞组成，包括血管周围巨噬细胞和外周来源的巨噬细胞，它们共同产生过量的抑制性细胞外基质成分，如胶原。先前的研究发现血管周围成纤维细胞（PVF）是中枢神经系统疾病中“纤维化”非神经病变疤痕的新来源。调节纤维化瘢痕形成的因素，更具体地说，是中枢神经系统疾病中PVF激活的因素，在很大程度上仍然未知。我们发现了血源性凝血因子纤维蛋白原作为潜在的初级成纤维细胞激活信号的意想不到的作用，指出纤维蛋白原是血管通透性和纤维化疤痕形成之间的分子联系。我们将通过使用药理学和遗传学工具来抑制/耗尽PVF细胞表面受体，确定纤维蛋白原对PVF激活和迁移影响疤痕成分的作用，并研究纤维蛋白原诱导的血管周围巨噬细胞活化对PVF激活的影响。我们将通过单细胞rna测序、RNAscope和免疫组织化学染色来确定纤维蛋白原诱导PVF分子特性的变化及其与髓系细胞的交叉通讯。最后，我们将操纵纤维蛋白原诱导的PVF激活，以改善大脑修复和功能。总的来说，这项研究将使我们能够确定新的分子靶点，以开发新的治疗方法来促进中风的功能恢复，然后可能适用于其他中枢神经系统损伤和疾病。

Scar formation is a common response to central nervous system (CNS) injury and disease and a major obstacle blocking CNS functional regeneration. The central non-neural “fibrotic” lesion core is composed of stromal cells, which are restricted to vascular and meningeal niches, and CNS-associated macrophages, including perivascular macrophages and peripherally derived macrophages, which together produce an excess of inhibitory extracellular matrix components, such as collagens. Previous work identified perivascular fibroblasts (PVF) as a novel source of the “fibrotic” non-neural lesion scar in CNS disease. Factors regulating fibrotic scar formation and, more specifically, PVF activation in CNS disease remain largely unknown. We identified an unexpected role for the blood-derived coagulation factor fibrinogen as a potential primary fibroblast activation signal, pointing to fibrinogen as a molecular link between vascular permeability and fibrotic scar formation. We will identify the effect of fibrinogen on PVF activation and migration affecting scar composition by utilizing pharmacologic and genetic tools to inhibit/deplete PVF cell surface receptors and to investigate the effect of fibrinogen-induced perivascular macrophage activation on PVF activation. We will determine the fibrinogen-induced changes in the molecular identity of PVF and their cross-communication with myeloid cells by single-cell RNA-Sequencing, RNAscope and immunohistochemical staining. Finally, we will manipulate fibrinogen-induced PVF activation towards improved brain repair and function. Overall, this study will enable us to pinpoint new molecular targets for the development of novel therapeutic approaches to promote functional recovery in stroke, which might then be applicable for other CNS injuries and diseases.