MicroRNA-224 mediates lipopolysaccharide-induced injury of pulmonary microvascular endothelium cells via regulating p21

Objective To investigate the effects of microRNA (miRNA, miR)-224 level changes on the lipopolysaccharide (LPS)-induced injury of pulmonary microvascular endothelium cells (PMVECs) and its mechanism. Methods Primary PMVECs were isolated from clean-level BALB/c mice and cultured in vitro. In order to induce cells injury, 1.0 mg/L LPS was used to treat PMVECs. MiR-224 inhibitor and p21 siRNA were transfected for silencing miR-224 and p21, respectively. The cell viability and apoptosis rate of PMVECs were detected by cell counting kit-8 reagent and flow cytometry, respectively. The changes of miR-224 and p21 were detected by fluorescent quantitative polymerase chain reaction (FQ-PCR) and Western blotting. Dual-luciferase reporter assay was used to determine the target relationship between miR-224 and p21. T-test was used to compare the mean between the two groups and the pairwise comparison of the mean among multiple groups was conducted by LSD test on the basis of one-way analysis of variance. Results After LPS treatment, the relative cell viability decreased to (42.333±7.586)% and apoptosis rate increased to (32.141±2.449)% as compared with non-LPS treated cells. Meanwhile, the level of miR-224 increased to 1.791±0.167 with a decreased p21 mRNA expression (0.527±0.058) (t=8.532, 7.261, 7.113 and 8.467, P<0.01). As compared with simple LPS treated cells, PMVECs transfected with miR-224 inhibitor showed lower cell inhibition and apoptosis rate after LPS treatment (F=62.618 and 32.643, P<0.01). However, p21 knock-down could antagonize the protective effect of miR-224. Conclusion MiR-224 may mediate the LPS-induced injury of PMVECs via targeting p21. MiR-224 could be a therapy target for acute lung injury/acute respiratory distress syndrome after sepsis. Key words: Sepsis; Lipopolysaccharide; Endotheliumcell; Acute lung injury; Acute respiratory distress syndrome; MicroRNA; P21