Melatonin‐Stimulated Mesenchymal Stem Cells‐Derived Exosomes Carrying LINC00052 Alleviate Hyperoxic Lung Injury by Promoting miR‐152‐3p‐KLF4‐Nrf2 Pathway

ABSTRACT Exposure of the lungs to high O2 levels, can lead to a noninfectious lung damage known as hyperoxia‐induced lung injury (HILI). Melatonin stimulation can enhance the efficacy of stem cells in some diseases. This study aims to investigate the mechanism of exosomes secreted by mesenchymal stem cells (MSCs) stimulated by melatonin in HILI. The MSCs‐derived exosomes were isolated and identified after stimulation with melatonin, and the neonatal rat model of HILI was constructed. After injection of exosomes and related lentiviruses, the ratio of wet lung to dry lung was calculated to evaluate pulmonary edema. Inflammatory factors in medium or serum were measured by ELISA. HE staining was used to evaluate the pathological status of lung tissue. Masson staining was used to evaluate collagen deposition in lung tissue. Lung cell apoptosis was detected by Tunel staining. In vitro model of HILI was established, CCK‐8 and EDU staining were used to detect cell viability and proliferation, and flow cytometry was used to detect cell apoptosis. The binding relationship between LINC00052, miR‐152‐3p, and KLF4 was verified through bioinformatics websites, dual luciferase reporter experiments, RIP experiments, and RNA pull down experiments. Melatonin‐stimulated MSCs‐derived exosomes could alleviate HILI. Exosomes had a therapeutic effect on HILI neonatal rats by carrying LINC00052. Inhibition of LINC00052 reversed the therapeutic effect of exosomes on HILI, while low expression of miR‐152‐3p or inducing KLF4 negated the effect of sh‐LINC00052. LINC00052 bound to miR‐152‐3p. miR‐152‐3p targeted KLF4. In vitro, melatonin‐stimulated MSC‐derived exosomes alleviated the cytotoxicity and cell viability inhibition of AEC‐II cells induced by hyperoxia. KLF4 overexpression activated NRF2 signaling in AEC‐II cells. LINC00052 in MSCs‐derived exosomes stimulated by melatonin activates the Nrf2 pathway through the miR‐152‐3p/KLF4 axis to alleviate HILI, which may be a potential therapeutic approach for HILI.