膜铁转运蛋白调控肺巨噬细胞双调蛋白参与脓毒症肺损伤发生发展的作用及机制研究

Lung injury is the most common organ dysfunction with a high mortality rate during sepsis. The disturbance of function in pulmonary macrophages would directly exacerbate and mediate the initiation and development of lung injury induced by sepsis. Ferroportin (Fpn), which is constitutively expressed on macrophages, has been implicated in immune response and bactericidal activity. Based on our previous work, we found that during sepsis-induced lung injury, the mortality of FpnLysM/LysM KO mice was significantly decreased compared with control mice. Meanwhile, lung tissue injury and the concentration of protein in bronchoalveolar lavage fluid were significantly improved in FpnLysM/LysM KO mice. Amphiregulin (Areg) is a bi-functional growth factor. Areg derived from macrophages plays a protect role in mice with lung injury induced by LPS. In our preliminary experiments, We also found there’s lower expression of Areg in macrophages of FpnLysM/LysM KO mice. Therefore, we hypothesize that Fpn will be involved in the pathogenesis of sepsis-induced lung injury via regulating the expression of Areg in pulmonary macrophages. The present project will aim to identify the functional role and molecular mechanism of Fpn in lung injury induced by sepsis. It will provide new insight into the pathogenesis of lung injury and might contribute to explore potentially novel therapeutic targets for the prevention and treatment of sepsis-induced lung injury.

肺损伤是脓毒症病程早期最常见的器官功能不全。巨噬细胞功能紊乱促进脓毒症肺损伤的发生发展。双调蛋白（amphiregulin，Areg）是一种具有双向调节作用的表皮生长因子，巨噬细胞高表达Areg对LPS诱导的肺损伤具有保护作用。我们前期研究：通过构建巨噬细胞膜铁转运蛋白（ferroportin，Fpn）特异性敲除小鼠，明显改善其脓毒症诱导的肺损伤的预后，肺损伤程度及肺泡灌洗液蛋白浓度显著降低；同时，Fpn抑制肺巨噬细胞Areg的表达。因此我们假设：Fpn通过调控肺巨噬细胞Areg分子的表达水平，介导脓毒症肺损伤的发病过程。本项目拟采用knock-out动物模型、RNA干扰等技术平台，从整体、细胞、分子水平阐明Fpn调控肺巨噬细胞Areg表达在脓毒症肺损伤中的作用及其分子机制，完善脓毒症肺损伤的病理生理研究，为临床探索有效防治脓毒症肺损伤提供新的理论基础。

肺损伤是脓毒症病程早期最常见的器官功能不全。巨噬细胞功能紊乱促进脓毒症肺损伤的发生发展。我们推测肺泡巨噬细胞通过膜铁转运蛋白（ferroportin，Fpn）介导双调蛋白（amphiregulin，Areg）的表达而在肺损伤的发生发展中具有重要作用。我们成功构建了巨噬细胞Fpn特异性敲除（KO）小鼠，并进一步成功建立了细菌感染的肺损伤模型。我们比较了KO小鼠和野生型小鼠肺损伤模型的生存率，肺损伤情况（包括肺组织学损伤评分，肺干湿比，肺泡灌洗细胞数量和蛋白浓度），肺上皮完整性，并深入探索了潜在的分子机制和治疗策略。我们发现：1）肺泡巨噬细胞FPN敲除明显降低肺损伤小鼠的死亡率，改善肺损伤程度，降低肺泡灌洗液蛋白浓度；2）肺泡巨噬细胞FPN敲除促进肺上皮细胞的增殖，促进肺上皮的完整性进而显著降低肺上皮通透性；3）肺泡巨噬细胞FPN敲除通过上调巨噬细胞Areg的表达发挥对肺损伤小鼠的保护作用；4）基于PROTAC技术的靶向FPN降解药物设计明显改善肺损伤小鼠的预后。本项目阐明了肺泡巨噬细胞FPN在细菌感染肺损伤中的作用和分子机制，这不仅为系统阐述肺损伤的发病机理提供新的理论依据，而且对有效防治肺损伤提供了新的分子靶标。