Telocytes Reduce Oxidative Stress by Downregulating DUOX2 Expression in Inflamed Lungs of Mice

Abstract

\n Background: Telocytes (TCs), a newly identified interstitial cell type, have been found to participate in tissue protection and repair. This study investigated the antioxidative effects of TCs in inflamed lungs of mice.Methods: Acute respiratory distress syndrome mice were used as model of inflamed lungs of mice. Gene sequencing was used to screen for differentially expressed miRNAs in TCs after lipopolysaccharide (LPS) stimulation. AntagomiR-146a-5p-pretreated TCs were first injected into mice, and the antioxidant activity of TCs was estimated. TCs, RAW264.7 cells, and MLE-12 cells were collected for mRNA, miRNA, and protein measurements after LPS stimulation. Silencing miRNAs were delivered to examine the involved signaling pathways in the experiments. Oxidative stress was examined in cultured cells, supernatants, and lung tissue by measuring malondialdehyde (MDA) levels.Results: MiR-146a-5p and miR-21a-3p were upregulated in TCs after LPS stimulation. Compared with ARDS mice, TC-preinfused ARDS mice had reduced lung tissue injury scores, lung wet-dry ratios, white blood cell counts in alveolar lavage fluid and MDA concentrations in lung tissue. However, ARDS mice preinfused with antagomiR-146a-5p TCs did not exhibit any of the corresponding changes. DUOX2 was downregulated in TCs at both the gene and protein levels, and the concentration of MDA was decreased in TCs and their culture medium after LPS stimulation. DUOX2 expression was restored when TCs were treated with antagomiR-146a-5p. CREB1 was downregulated by miR-146a-5p, as confirmed by a dual-luciferase reporter assay, and the protein expression of DUOX2 was downregulated by CREB1, which was further confirmed by treating TCs with a specific CREB1 inhibitor.Conclusion: LPS stimulation increases miRNA-146a-5p expression in TCs, which downregulates the CREB1/DUOX2 pathway, resulting in a decrease in oxidative stress in cultured TCs. TCs reduce LPS-induced oxidative stress by decreasing DUOX2 expression in inflamed lungs of mice.