利用"血管微环境重构"的节点通路促进肺再生并抑制纤维化

Lung diseases remain leading death causes. Regenerative therapy that aims to stimulate the regeneration of diseased lung tissue may provide promising treatment. Nevertheless, aberrant remodeling of pulmonary microenvironment frequently prohibits lung regeneration at pathological conditions such as lung fibrosis. Thus, elucidating how remodeling vascular microenvironment regulates lung regeneration and fibrosis has translational value. Our previous work demonstrates that endothelial cells (ECs) lining vascular lumen elaborate paracrine factors to stimulate the propagation of local facultative stem cells, functionalizing vascular niche that drives organ regeneration (Cao*..Ding* Nature Medicine 2016; Rafii..Ding* Nature Cell Biology 2015; Ding*, Cao..Nature 2014; Ding..Nature 2010; Ding..Cell 2011; Cao, Ding*..Cancer Cell 2014). This transformative notion that advances our traditional view of vascular cells as passive conduit delivering oxygen and blood. Furthermore, we also identified that key checkpoint pathways in vascular niche such as S1P1 determine the generation of pro-regenerative and anti-fibrotic factors in ECs, enabling "adaptive remodeling of vascular niche" in organ regeneration and repair. In contrast, suppression of these pathways by persistent activation of FGFR1 leads to "maladaptive remodeling of vascular niche" that instigates organ fibrosis. However, a thorough investigation of how remodeling vascular niche balances lung regeneration and fibrosis in various injury settings is lacking. As such, this application aims to define key checkpoint pathways by which remodeling vascular niche orchestrates the regeneration of damaged lungs...We will focus on revealing the central checkpoint pathways enabling the "adaptive vascular niche remodeling" that directs lung regeneration and prevents fibrosis. We will 1) delineate the molecular basis via which key checkpoint pathways determine the pro-regenerative "adaptive" versus pro-fibrotic "maladaptive" remodeling of vascular niche. Mouse EC-specific gene gain and loss of function strategy will be combined with complementary animal lung repair models to reveal the contribution of these checkpoint pathways; 2) uncover cellular players modulating the critical checkpoint pathways involved in vascular niche remodeling. Based on our previous work implicating the role of platelets in modulating vascular niche, we will examine the influence of these blood cells on vascular niche remodeling; 3) devise "interdisciplinary" approach to induce “adaptive vascular niche remodeling” that promotes regeneration and curtails fibrosis. This proposal will answer a fundamental question involved in vascular, regenerative and lung biology: how to remodel an inviting vascular niche to induce lung regeneration without fibrosis. As such, positive outcome of this study will hold therapeutic potential for vascular and lung diseases. The findings of the proposed study will also conceptually advance our understanding of how remodeling vascular niche orchestrates regeneration and repair in different organs.

肺部疾病在我国有近5000万患者。促进肺再生对恢复病变肺的功能有重要的作用。然而病变肺如纤维化肺中的不正常重构的微环境对肺再生有抑制作用。改变病变肺微环境可抑制纤维化并促进肺再生。我们发表在 Nature (2010,2014),Cell (2011), Cancer Cell(2014), Nature Cell Biology(2015)，Nature Medicine (2016)的工作首次提出：血管内皮细胞形成“引导性微环境”调控器官再生，并防止纤维化。而血管微环境重构的节点由血小板和单核细胞调控。本项目中我们将研究肺修复中血管微环境是如何重构并促进再生，通过揭示血管内皮细胞、肺干细胞及血液细胞的相互作用阐明这一过程中的关键分子节点调控机制。我们还使用血管靶向基因编辑手段重构促再生的血管微环境。因此，本项目研究基于“血管微环境重构”在肺再生的作用和机制，具有很好的创新性和应用价值。

目前器官纤维化仍然缺乏有效的治疗手段。本申请着重于阐明血管细胞是如何通过关键节点通路形成微环境对器官修复进行调控。我们利用肺损伤模型中研究如何利用血管特异性药物传输达到“编辑病变器官的血管微环境节点通路”的目的。探索这些策略将发掘防止纤维化等恶性转变中的治疗效应。.针对这一成果目标，设置了相对应的考核指标。.1．测试肺二型干细胞和基底细胞在器官纤维化模型的作用；.2．发掘血管微环境关键节点通路对器官再生和纤维化反应的调节；.3．利用“血管基因靶向”手段选择性调控节点通路在血管微环境中表达而防止肺纤维化。.在项目立项时，本团队已建立器官修复模型。并已经建立基于假型慢病毒的高效血管特异性基因表达系统，为纤维化的治疗研究奠定了基础。..本项目执行期间，在器官的修复和和纤维化的研究中我们也发现了血管微环境节点S1P通路对器官再生有促进作用，并且可以有效防止纤维化。同时我们还发现血管微环境的节点分子hepatocyte growth factor (HGF)可以防止器官纤维化。于此同时，通过在血管系统中选择表达HGF分子，我们成功地在小鼠模型中实现了人上皮干胞移植，同时增强了器官功能的恢复。本项目研究在Science 子刊Science Translational Medicine发表，并标注基金。本研究发掘了血管微环境在肺再生过程中由良性重构到恶性重构的“关键节点通路“（HGF-NOX4 通路）。HGF 和NOX4 的相互作用是血管微环境对组织再生和纤维化调控的一个重要节点，在器官的功能性修复和干细胞植入都发挥重要作用。我们的研究结果研究阐明了HGF 和NOX4 对器官纤维化的调控机制，有助于了解关键科学问题“血管重构的关键节点通路”。同时我们的研究工作也建立了如何利用基因编辑恢复血管微环境促再生功能的方法手段。发现重新表达HGF 基因和抑制NOX4 不正常活力可以恢复组织稳态的血管微环境。最终我们将通过“重建血管微环境”达到恢复“促再生的稳态血管微环境”的目的 。这有助于了解第二个关键科学问题“控制血管稳态的调控网络与关键节点”。