[The microRNA-21-5p regulation of type II alveolar epithelial cell apoptosis]

To explore whether microRNA-21-5p (miR-21-5p) has the effect of anti-apoptosis of human alveolar type II epithelial cells (AT II).

AT II cells derived from the human were cultured in vitro and used for experiments when the cells were grown until the presence of lamellar bodies and microvilli were observed by light microscope. The cells were divided into blank control group (direct culture), hydrogen peroxide (H₂O₂) injury group (cultured with 0.5 mmol/L H₂O₂), and miR-21-5p overexpression group (using miR-21-5p with a multiplicity of infection (MOI) of 100 lentiviral overexpression vector with 0.5 mmol/L H₂O₂) and miR-21-5p empty virus control group (miR-21-5p lentiviral blank vector was co-cultured with 0.5 mmol/L H₂O₂). In each group, cell proliferation was detected by cell counting kit-8 (CCK-8) at 0, 12, 24, 36, and 48 hours of cell culture; cell apoptosis was detected by flow cytometry at 24 hours of culture.

(1) Cell proliferation activity test results: with the extension of cell culture time, the cell proliferation activity of the blank control group gradually increased, while the cell proliferation activity gradually decreased after the addition of 0.5 mmol/L H₂O₂. However, the cells proliferation activity in the miR-21-5p overexpression group decreased more slowly than that in the H₂O₂ injury group and the miR-21-5p empty virus control group, and the cell proliferation activity at 48 hours was significantly higher than the H₂O₂ injury group and the miR-21-5p empty virus control group (A value: 0.295±0.005 vs. 0.184±0.005, 0.169±0.002, both P < 0.05). It showed that both H₂O₂ and lentivirus accelerated cell damage, while miR-21-5p could reduce cell apoptosis. (2) Apoptosis rate test results: compared with the blank control group, the apoptosis rate increased significantly after adding 0.5 mmol/L H₂O₂; while the apoptosis rate of the miR-21-5p overexpression group was lower than that of the H₂O₂ injury group and miR-21-5p empty virus control group [early apoptosis rate: (14.31±0.12)% vs. (24.50±0.12)%, (23.41±0.13)%; late apoptosis rate: (8.12±0.13)% vs. (9.71±0.11)%, (10.41±0.15)%; overall apoptosis rate: (22.33±0.12)% vs. (34.21±0.10)%, (33.82±0.14)%; all P < 0.05], which further proved that miR-21-5p had anti-apoptotic effects.

miR-21-5p has an anti-apoptotic effect on human AT II.