Effect of overexpression of microRNA-21-5p on early apoptosis of typeⅡalveolar epithelial cells in rats with hyperoxic acute lung injury / 中华危重病急救医学

ABSTRACT

To investigate the effect of overexpression of microRNA-21-5p (miR-21-5p) on early apoptosis of type Ⅱalveolar epithelial cells (AECⅡ) in rats with hyperoxic acute lung injury (HALI). Methods The Sprague-Dawley (SD) rats were randomly divided into four groups: control group (CON group), hyperoxia group (H group), overexpression group (OE group) and empty vector group (EV group), with 20 rats in each group. HALI animal model was made by inhaling high concentration oxygen (oxygen concentration ≥90%); CON group was arranged to inhale room air. The miR-21-5p adeno-associated virus-6 (AAV-6) overexpression vectors or empty vectors were dripped into the lungs of OE group and EV group through tracheal tube, respectively. The hyperoxia model was prepared after 3 weeks of feeding. At 0, 24, 48 and 60 hours after making model, 5 rats were selected to detect lung injury parameters:oxygenation index (OI), respiratory index (RI), wet/dry ratio (W/D), pathological injury score of lung tissue; real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of miR-21-5p in AECⅡ, and flow cytometry was used to detect the early apoptotic rate of AECⅡ. Results ① The lung injury parameters: in H group, the OI gradually decreased with time, but the RI, lung W/D ratio and pathological score increased gradually with time, the difference between CON group was statistically significant at 24 hours [OI (mmHg, 1 mmHg = 0.133 kPa):336.04±5.79 vs. 400.22±19.70, RI: 0.20±0.02 vs. 0.10±0.06, lung W/D ratio: 5.04±0.09 vs. 4.85±0.09, lung tissue pathological score: 0.13±0.01 vs. 0.07±0.01, all P < 0.05]. It indicated that HALI model could be successfully established by inhaling high concentration oxygen continuously. ② The expression of miR-21-5p: the miR-21-5p was gradually increased in H, OE and EV groups, and the expression of miR-21-5p was significantly higher than that in CON group at 24, 48 and 60 hours. Compared with H group, the expression of miR-21-5p was significantly increased further in OE group at 0, 24, 48 and 60 hours (2-ΔΔCt: 3.75±0.11 vs. 0.98±0.14, 3.98±0.12 vs. 1.18±0.13, 4.28±0.18 vs. 1.49±0.06, 4.66±0.12 vs. 1.80±0.12, all P < 0.05). ③ The early apoptosis of AECⅡ: the early apoptosis rate gradually increased with time in H, OE and EV groups, and the early apoptosis of AECⅡ was significantly higher than that in CON group at 24, 48 and 60 hours. Compared with H group, the early apoptosis rate was significantly decreased in OE group at 24, 48 and 60 hours [(1.22±0.63)% vs. (2.84±0.59)%, (5.76±0.18)% vs. (13.10±2.01)%, (29.48±0.48)% vs. (49.04±1.36)%, all P < 0.05]. ④ There was no significant difference in the expression of miR-21-5p and the early apoptosis of AECⅡ cells between EV group and H group at each time point. Conclusion Overexpression of miR-21-5p could inhibit the early apoptosis of AECⅡ in rats with HALI.