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

Abstract

Objective

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, suggesting approaches to induce autophagy can be used to ameliorate psoriasis.

Keywords:

• autophagy
• inflammatory
• HUVECs
• p38 MAPK/mTOR

Abbreviations

HUVECs, Human umbilical vein endothelial cells; LC3, Light chain 3; p38 MAPK, p38 Mitogen-activated protein kinase; ULK1, unc-51 like kinase 1, mTOR, mammalian target of rapamycin; RAPA, Rapamycin; CQ, Chloroquine; NO, Nitric oxide; EGM-2, Endothelial cell growth medium-2.

Data Sharing Statement

All data are available upon request.

Ethics Approval and Consent to Participate

Ethical approval for the experiments was obtained from the Medical Ethics Committee of Taiyuan City Centre Hospital, and all subjects provided informed consent.

Disclosure

The authors declare no conflicts of interest in this work.

Additional information

Funding

This project was supported by the National Natural Science Foundation of China (grant no.81773336, 81803146, 81472888).