miR-155通过SHIP1对肺间质纤维化内皮-间充质转化的调控作用及机制

Pulmonary fibrosis characterized with excessive proliferation of lung fibroblasts is a common outcome of a variety of interstitial lung diseases. Endothelial-mesenchymal transition (EndMT) is a vital origin of fibroblasts, which contributes to the promotion of pulmonary fibrosis progression. In plenty of factors that regulate EndMT, microRNAs (miR) play a significant role. We found that miR-155 gene knockout in vivo can inhibit the progress of pulmonary fibrosis in mice; its target gene SHIP1 may protect the pulmonary fibrosis through EndMT. However, the study of miR-155→SHIP1→EndMT in pulmonary fibrosis is still blank. Therefore, the role of miR-155 and SHIP1 in the progression of pulmonary fibrosis will be clarified with gene knockout mice; meanwhile, the mechanism of miR-155 regulating EndMT through SHIP1 will be demonstrated by analyzing the mesenchymal transition of different genotype pulmonary endothelial cells under specific conditions; and then, the effect of miR-155→SHIP1→EndMT on the progress of pulmonary fibrosis will be discussed in vivo. The aim of this study is to reveal the mechanism of miR-155 promoting the progression of pulmonary fibrosis through EndMT and to provide a theoretical basis for the treatment of the disease from EndMT.

肺间质纤维化是多种间质性肺疾病的共同结局，肺成纤维细胞过度增殖是该病进展特征。内皮-间充质转化（EndMT）是成纤维细胞重要来源，能够促进肺纤维化进展。调控EndMT众多因子中，微小RNA（miR）的作用不可低估。我们发现，体内miR-155基因敲除能抑制小鼠肺纤维化进展；其靶基因SHIP1可能通过EndMT对肺纤维化起保护作用。但有关miR-155→SHIP1→EndMT在肺纤维化领域的研究尚属空白。因此，我们在前期基础上，利用基因敲除小鼠，明确miR-155、SHIP1在肺纤维化进展中的作用；通过探讨不同基因型肺内皮细胞在特定条件下的间充质转化，明确miR-155通过SHIP1对EndMT的调控及机制；最后在体内阐述miR-155→SHIP1→EndMT对肺纤维化进展的影响。本课题旨在揭示miR-155通过EndMT促进肺纤维化进展的机制，为从EndMT角度治疗该病提供理论依据。

SHIP-1是促炎因子miR-155的一个靶点，SHIP-1基因缺失导致小鼠自发的肺部炎症和纤维化。然而，内皮细胞miR-155和SHIP-1在肺纤维化中的作用和功能尚不清楚。使用全身miR-155敲除小鼠和内皮细胞特异性条件miR-155 (VEC- Cre -miR-155，或VEC-miR-155)或SHIP-1敲除小鼠，我们评估了博莱霉素(BLM)诱导的肺纤维化模型中的内皮-间质转化(EndMT)和纤维化过程。不同基因型原代鼠肺内皮细胞(MLEC)和人类脐静脉内皮细胞(HUVEC) （有无SHIP-1）分别予以TGF -beta-1或BLM分别诱导，探讨其纤维化过程EndMT反应。结果表明，在体内，mir - 155 ko小鼠纤维化和EndoMT显著降低；而体外实验发现，内皮细胞予以 TGF beta-1刺激后其内皮细胞标记下调，而纤维化指标显著上调，证实了体内研究结果。此外，与WT小鼠相比较，BLM刺激后，VEC-miR-155小鼠的肺纤维化和EndoMT反应及程度下降；但VEC-SHIP-1小鼠的肺纤维化和EndMT反应显著增强。在HUVEC细胞中，SHIP-1基因敲除导致了BLM诱导的EndoMT增强。同时，这些变化涉及PI3K/AKT、JAK/STAT3和SMAD/STAT信号通路。研究表明，内皮细胞miR-155通过EndMT在肺纤维化反应中发挥重要作用，内皮细胞SHIP-1在控制纤维化反应中至关重要。总之，我们从miR-155→SHIP1→EndMT角度，发现miR-155-/-PMVECs具备SHIP1依赖的拮抗EndMT表型，阐明了miR-155能对PMEVCs内SHIP1-EndMT进行调控，最终提出miR-155通过SHIP1-EndMT对肺纤维化的干预机制。