低分子量透明质酸诱导肺微血管内皮细胞自噬介导脓毒症急性肺损伤的机制研究

肺微血管内皮细胞屏障功能障碍是脓毒症急性肺损伤的重要原因。研究示：诱导肺微血管内皮细胞自噬下调细胞间连接相关蛋白表达，破坏细胞屏障。我们已发表文章证实：低分子量透明质酸（L-HA）可致肺微血管内皮细胞屏障功能障碍，诱发急性肺损伤，但具体机制不明。进一步体外研究发现：敲除L-HA特异性受体CD44的小鼠肺微血管内皮细胞在L-HA刺激后，自噬核心蛋白LC3B表达明显下降。由此推测：脓毒症损伤产物L-HA，通过上调LC3B表达，诱导肺微血管内皮细胞自噬，破坏细胞间连接，导致屏障功能障碍和急性肺损伤。为证明此假说，拟利用CD44-/-和LC3B-/-小鼠构建脓毒症急性肺损伤模型以及L-HA诱导原代肺微血管内皮细胞自噬的细胞实验，阐明L-HA诱导肺微血管内皮细胞自噬损伤细胞屏障功能的具体机制，为临床治疗脓毒症急性肺损伤提供理论基础和实验依据。

Pulmonary microvascular endothelial cell (PMVEC) barrier dysfunction is the main cause of sepsis-induced acute lung injury. Recent studies indicated that induction of PMVEC autophagy downregulated protein expression of cell junction, and destroyed the cell barrier. Our published paper shown that low molecular weight hyaluronan (L-HA) mediated PMVEC barrier dysfunction and acute lung injury, however, the specific mechanism is unknown. Additionally, research in vitro shown that knockout CD44 on PMVEC, the specific L-HA receptor, could downregulate the expression of the specific autophagy protein LC3B, if treated with L-HA. Therefore, we assume that, the injury product L-HA induced by sepsis, upregulates expression of LC3B, activates PMVEC autophagy, destroys cell junction, and causes cell barrier dysfunction and acute lung injury. In this project, we establish sepsis-induced acute lung injury model by using wildtype，CD44-/- and LC3B-/-mice, and L-HA induced primary PMVEC autophagy to explore the specific mechanism of L-HA-induced autophagy of PMVEC cause cell barrier dysfunction, which may provide the experimental and theoretical foundation for the application of L-HA as the therapeutic target for clinical treatment of sepsis-induced acute lung injury.