Asiaticoside Attenuates Burn Serum-induced Human Dermal Microvascular Endothelial Cell Injury via Regulating ACTN4-mediated p38-MAPK/p53 Signaling Pathway

Background: Asiaticoside has been affirmed to enhance the healing process of burn wounds, but the underlying molecular mechanism needs to be further elucidated. Therefore, this study aims to investigate the mechanism by which asiaticoside affects the burn serum-induced human dermal microvascular endothelial cell (HDMVEC) injury.Methods: Sprague-Dawley (SD) rats (n = 20) were divided into two groups: the burn group and the Sham group. Rats in the burn group were exposed to an electrically heated brass rod. HDMVECs were transfected with small interfering RNA targeting alpha-actinin-4 (ACTN4) (siACTN4) and negative control of siACTN4 (siNC). Burn serum-induced HDMVEC injury was used to mimic microvascular injury in vivo. Furthermore, HDMVECs were treated with asiaticoside and SB203580 (p38 mitogen-activated protein kinase (MAPK) specific inhibitor). The monolayer permeability in HDMVECs was evaluated using transendothelial electrical resistance, and cell viability was assessed using cell counting kit-8 (CCK-8) assay. The localization of zonula occludens-1 (ZO-1) and filamentous actin (F-actin) was determined through immunofluorescence staining. Moreover, the mRNA/protein expression levels of ACTN4, phosphorylated (p)-p53, p53, p-p38, and p38 in treated HDMVECs were evaluated using quantitative real-time PCR (qRT-PCR) and Western blot analysis.Results: Asiaticoside negated the inhibitory impacts of burn serum on viability and F-actin levels in HDMVECs (p < 0.05) as well as the promotive impacts of burn serum on monolayer permeability and ZO-1 levels. The expression of ACTN4 at both mRNA and protein was downregulated in burn serum-induced HDMVECs and upregulated by asiaticoside (p < 0.05). Asiaticoside reduced the protein expression levels of p-p53/p53 and p-p38/p38 and level of ZO-1, suppressed the monolayer permeability as well as promoted F-actin level and viability in burn serum-induced HDMVECs, all of which could be reversed by ACTN4 silencing (p < 0.05). Furthermore, SB203580 further offset the impacts of ACTN4 silencing on the protein expression levels of p-p53/p53 and p-p38/p38, levels of ZO-1 and F-actin as well as the monolayer permeability in burn serum-induced HDMVECs (p < 0.05).Conclusions: These findings suggest that asiaticoside enhances the healing process in burn serum-induced HDMVEC injury by regulating the ACTN4-mediated p38-MAPK/p53 signaling pathway.