The miR-21-5p/DUSP8/MAPK signaling pathway mediates inflammation and apoptosis in vascular endothelial cells induced by intermittent hypoxia and contributes to the protective effects of N-acetylcysteine.

Obstructive sleep apnoea hypopnea syndrome (OSAHS) is a sleep disorder associated with significant cardiovascular complications, characterized by intermittent hypoxia (IH). IH causes endothelial dysfunction, an early event in cardiovascular disease. We investigated the role of dual-specificity phosphatase 8 (DUSP8), a key negative regulator of the mitogen-activated protein kinase (MAPK) signalling pathway, in IH-induced endothelial cell damage, and the therapeutic effects of N-acetylcysteine (NAC) by establishing IH models in human umbilical vein endothelial cells and C57BL/6 mice. DUSP8 and MAPK signalling pathway-related proteins were analysed by western blotting, and DUSP8 mRNA and miR-21-5p expression was assessed by RT-qPCR. Inflammatory cytokines were detected by an enzyme-linked immunosorbent assay, apoptosis-related proteins were analysed by western blotting, and apoptosis was assessed using flow cytometry. IH stimulation induced inflammation and apoptosis in endothelial cells, downregulated DUSP8 expression, and upregulated the phosphorylation of key molecules involved in the MAPK signalling pathway. However, DUSP8 overexpression alleviated IH-induced inflammation and apoptosis in endothelial cells and reduced the phosphorylation of key molecules in the MAPK signalling pathway. Bioinformatic analysis and dual-luciferase reporter assays confirmed that DUSP8 is a direct target of miR-21-5p. DUSP8 overexpression effectively reversed the damage caused by miR-21-5p upregulation under IH conditions. Furthermore, in cell and animal models of IH, NAC demonstrated protective effects against inflammation, apoptosis, and oxidative stress through a mechanism linked to the miR-21-5p/DUSP8/MAPK signalling pathway. Overall, this study elucidated the protective role of DUSP8 against IH-induced endothelial injury and confirmed the potential of NAC as a therapeutic agent for OSAHS-related diseases.