MiR-21-5p alleviates hyperoxia-induced acute lung injury by inhibiting ferroptosis through the STAT3/P53/SLC7A11 axis

To investigate whether microRNA-21-5p (miR-21) plays a protective role in hyperoxia-induced acute lung injury (HALI) by regulating ferroptosis through the STAT3/P53/SLC7A11 axis.

The interaction between STAT3 and P53 was analyzed by co-immunoprecipitation (Co-IP). Fifty 9-week-old male C57BL/6J mice were randomly divided into normoxia (Control) group, HALI group, miR-21 overexpression (miR-21) group, STAT3 inhibitor (HY-13818) group, and ferrostatin-1 (Fer-1) group. After the mice from the miR-21 group received miR-21-5p AAV6 or empty vector via tracheal catheter instillation, the animals were then monitored for 3 weeks. The HY-13818 group was intraperitoneally injected with HY-13818 (10 mg/kg) 3 times weekly for 2 weeks. The Fer-1 group received 0. 8 mg/kg ferrostatin-1 via tail vein injection once daily for 2 consecutive days during modeling. The HALI model was established by exposure to >90% oxygen. After 48 h of hyperoxia, blood samples were collected via orbital sampling for RT-PCR analysis of miR-21 expression. Lung tissues were harvested for wet/dry weight ratio and assessment of histopathological changes via HE staining for lung injury score. Activity of superoxide dismutase (SOD) and contents of malondialdehyde (MDA), Fe²⁺, glutathione (GSH), and reactive oxygen species (ROS) were measured using photocolorimetry, spectrophotometry and fluorometry. Western blotting was used to evaluate the protein expression of STAT3, P53, SLC7A11, and GPX4.

The results of Co-IP showed that STAT3 could bind to P53. The HALI group exhibited obviously destroyed alveolar structure, disordered arrangement, thickened interval, with a large number of infiltrated neutrophils and collapsed alveoli, and had significantly increased pathological score of lung injury and ratio of lung W_wet/D_dry weight when compared with the Control group (P<0. 05). In the miR-21 group, HY-13818 group and Fer-1 group, the severity of lung injury was significantly reduced, and the pathological score of lung injury and the ratio of W_wet/D_dry weight were decreased (P<0. 05) when compared with the HALI group. Compared with the control group, the contents of MDA, Fe²⁺ and ROS were increased (P<0. 05), the activity of SOD and content of GSH were declined (P< 0. 05), the protein levels of STAT3 and P53 were increased (P<0. 05), and those of SLC7A11 and GPX4 were decreased (P<0. 05) in the HALI group. Compared with the HALI group, decreased MDA and ROS levels (P< 0. 05), enhanced SOD activity, Fe²⁺ and GSH levels (P<0. 05), down-regulation of STAT3 and P53 (P<0. 05) and up-regulation of SLC7A11 and GPX4 (P<0. 05) were observed in the miR-21 group and HY-13818 group.

MiR-21 alleviates HALI, which may be related to its inhibition of ferroptosis through the STAT3/P53/SLC7A11 axis.