Thy-1 depletion and integrin β3 upregulation-mediated PI3K-Akt-mTOR pathway activation inhibits lung fibroblast autophagy in lipopolysaccharide-induced pulmonary fibrosis
Thy-1 depletion and integrin β3 upregulation-mediated PI3K-Akt-mTOR pathway activation inhibits lung fibroblast autophagy in lipopolysaccharide-induced pulmonary fibrosis
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Thy-1 耗竭和整合素 β3 上调介导的 PI3K-Akt-mTOR 通路激活抑制脂多糖诱导的肺纤维化中的肺成纤维细胞自噬
DOI：
10.1038/s41374-019-0281-2
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发表时间：
2019-11-01
影响因子：
5
通讯作者：
He, Zhengyu
中科院分区：
文献类型：
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作者：
Wan, Hanxi;Xie, Tingting;He, Zhengyu
脂多糖（LPS）诱导的肺成纤维细胞自噬抑制与磷脂酰肌醇3-激酶/蛋白激酶B/哺乳动物雷帕霉素靶蛋白（PI 3 K-Akt-mTOR）通路的激活密切相关。然而，其潜在机制仍不清楚。在这项研究中，我们证明了LPS激活PI 3 K-Akt-mTOR通路，并通过耗尽胸腺细胞分化抗原-1（Thy-1）和上调整合素β3（Itgb 3）来抑制肺成纤维细胞自噬。用LPS攻击人肺成纤维细胞MRC-5细胞系导致整合素β3的显著上调、PI 3 K-Akt-mTOR通路的激活和自噬的抑制，这可以通过特异性shRNA沉默整合素β3或用整合素β3抑制剂西仑吉肽处理来消除。同时，LPS可抑制Thy-1的表达，并伴有PI 3 K-Akt-mTOR通路的激活和肺成纤维细胞自噬的抑制，Thy-1的过表达可逆转这些作用。同时，Thy-1 shRNA下调Thy-1表达可模拟LPS作用，诱导PI 3 K-Akt-mTOR通路激活，抑制肺成纤维细胞自噬。此外，蛋白质免疫沉淀分析表明，LPS降低了Thy-1与整合素β3的结合。在LPS诱导的肺纤维化小鼠模型中也检测到Thy-1下调、整合素β3上调和自噬抑制，这可以通过气管内注射Thy-1过表达的腺相关病毒（AAV）或腹腔内注射整合素β3抑制剂西仑吉肽来抑制。结论：Thy-1缺失和整合素β3表达上调参与了LPS诱导的肺纤维化，可能成为治疗肺纤维化的潜在靶点。
Lipopolysaccharide (LPS)-induced autophagy inhibition in lung fibroblasts is closely associated with the activation of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K-Akt-mTOR) pathway. However, the underlying mechanism remains unknown. In this study, we demonstrated that LPS activated the PI3K-Akt-mTOR pathway and inhibited lung fibroblast autophagy by depleting thymocyte differentiation antigen-1 (Thy-1) and upregulating integrin β3 (Itgb3). Challenge of the human lung fibroblast MRC-5 cell line with LPS resulted in significant upregulation of integrin β3, activation of the PI3K-Akt-mTOR pathway and inhibition of autophagy, which could be abolished by integrin β3 silencing by specific shRNA or treatment with the integrin β3 inhibitor cilengitide. Meanwhile, LPS could inhibit Thy-1 expression accompanied with PI3K-Akt-mTOR pathway activation and lung fibroblast autophagy inhibition; these effects could be prevented by Thy-1 overexpression. Meanwhile, Thy-1 downregulation with Thy-1 shRNA could mimic the effects of LPS, inducing the activation of PI3K-Akt-mTOR pathway and inhibiting lung fibroblast autophagy. Furthermore, protein immunoprecipitation analysis demonstrated that LPS reduced the binding of Thy-1 to integrin β3. Thy-1 downregulation, integrin β3 upregulation and autophagy inhibition were also detected in a mouse model of LPS-induced pulmonary fibrosis, which could be prohibited by intratracheal injection of Thy-1 overexpressing adeno-associated virus (AAV) or intraperitoneal injection of the integrin β3 inhibitor cilengitide. In conclusion, this study demonstrated that Thy-1 depletion and integrin β3 upregulation are involved in LPS-induced pulmonary fibrosis, and may serve as potential therapeutic targets for pulmonary fibrosis.