Autophagy Inhibits Inflammation via Down-Regulation of p38 MAPK/mTOR Signaling Cascade in Endothelial Cells

Ling Zhou,1 Juanjuan Wang,1 Hui Hou,1 Jiao Li,1 Juan Li,1 Jiannan Liang,1 Junqin Li,1 Xuping Niu,1 Ruixia Hou,1 Kaiming Zhang2 1Shanxi Key Laboratory of Stem Cells for Immunological Dermatosis, Institute of Dermatology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, People’s Republic of China; 2Shanxi Key Laboratory of Stem Cells for Immunological Dermatosis, Institute of Dermatology, Taiyuan Central Hospital, Taiyuan, People’s Republic of ChinaCorrespondence: Kaiming Zhang, Taiyuan Central Hospital, Taiyuan, People’s Republic of China, Tel/Fax +86-351-5656080, Email zhangkaiming@sina.com; tycchospital@sina.comObjective: Autophagy, an intracellular process of self-digestion, has been shown to modulate inflammatory responses. In the present study, we determined the effects of autophagy on inflammatory response induced by M5 cytokines.Methods: Human umbilical vein endothelial cells (HUVECs) were treated with M5 cytokines to induce inflammation. Expression levels of mRNA for inflammatory cytokines and BIRC2 were compared in HUVECs with vs without induction of autophagy with rapamycin (RAPA) by PCR, while cell apoptosis was assessed by flow cytometry and caspase-3 activity assay kit. Expression levels of LC3, p62, p-p38 MAPK (Thr180/Tyr182), p-mTOR (Ser2445) and p-ULK1 (Ser555) proteins were measured by Western blotting. The nitric oxide (NO) content, NO synthase (NOS) activity and cell angiogenesis were also evaluated.Results: Induction of autophagy with RAPA decreased expression levels of IL6, IL8 and CCL20, in addition to reduction in inflammation-induced apoptosis in HUVECs. Moreover, RAPA increased LC3II, while decreasing p62 expression. Likewise, expression levels of p-p38 MAPK and p-mTOR proteins were markedly decreased by the treatment with RAPA. Finally, RAPA treatment increased the NO content and the NOS activity, and inhibited angiogenesis.Conclusion: Induced autophagy can improve the function of endothelial cells in psoriasis, suggesti