Study of the Regulatory Mechanism of miR-26a-5p in Allergic Asthma

Objective: Allergic asthma is a growing burden on national public health services due to its high prevalence. The aim of this experiment was to investigate whether miR-26a-5p affects cellular fibrosis and thus airway remodeling in asthmatic mice through the regulation of target genes. Methods: Screening for differentially expressed miRNAs in asthma model mice was carried out by constructing a mouse model of allergic asthma. qRT-PCR was performed to determine candidate miRNAs in each group of bronchial tissues. Western blot detection of the expression levels of predicted candidate target genes in each group of bronchial tissues was conducted. A dual luciferase assay was performed to validate the binding of miR-26a-5p to target genes. Fibronectin, a marker of cellular fibrosis, was detected via flow cytometry. CCK8 and BrdU staining were used to detect the proliferation ability of each group of cells. Results: miR-26a-5p is able to target and bind to ABL2 3′-UTR, MMP16 3′-UTR and PDE7A 3′-UTR sequences. After interference with miR-26a-5p, improved bronchial histopathology and reduced peribronchial collagen deposition were found. Compared with the model group, interference with miR-26a-5p reduced lung fibrosis, decreased fibroblasts and increased apoptosis in mouse bronchial tissues; overexpression of miR-26a-5p decreased apoptosis in mouse bronchial tissues. Compared with the model group, the serum levels of IL-4, IL-5, IL-13 and I IFN-γ were decreased in the miR-26a-5p inhibitor group and increased in the miR-26a-5p mimic group. The immunohistochemical results showed that the expression of ABL2, MMP16 and PDE7A was significantly reduced after intervention with miR-26a-5p. Compared with the model group, the apoptosis rate of cells in the miR-26a-5p inhibitor group of the allergic asthma model was upregulated, the levels of IL-4, IL-5, IL-13, IFN-γ and ROS were decreased, the expression of the miRNA and proteins of ABL2, MMP16 and PDE7A was decreased, the expression of LC3A and P62 was significantly increased and the expression of LC3B, Beclin1, Atg5 and fibrosis markers collagen I and α-SMA was decreased. Conclusion: miR-26a-5p affects cellular fibrosis and thus airway remodeling in asthmatic mice by regulating target genes.