Autophagy inhibits inflammation via down-regulation of p38 MAPK/mTOR signaling cascade in endothelial cells

Abstract: 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 supernatant of psoriatic dermal mesenchymal stem cells (p-DMSCs). Human umbilical vein endothelial cells (HUVECs) were treated with supernatant of p-DMSCs cultures to induce inflammation and treated with rapamycin (RAPA) to induce autophagy. 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. We found that induction of autophagy with RAPA decreased expression levels of IL6, IL8 and CCL20, in addition to reduction in inflammation-induced apoptosis in HUVECs; Expression levels of LC3, p62, p-p38 MAPK (Thr180/Tyr182), p-mTOR (Ser2445) and p-ULK1 (Ser555) proteins were measured by Western blotting. We found 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, we evaluated thenitric oxide (NO) content, NO synthase (NOS) activity and cell angiogenesis. RAPA treatment increased the NO content and the NOS activity, and inhibited angiogenesis. Through the experimental results, we speculated that induced of autophagy can improve the function of endothelial cells in psoriasis, suggesting approaches to induce autophagy can be used to ameliorate psoriasis.