The Role Of MiR-107 In Allergic Asthma

Asthma is a chronic inflammatory disease of the airway.With increasing morbidity and mortality,asthma has become a worldwide concern,with approximately 60%of patients suffering from allergic asthma.The main clinical manifestations are recurrent wheezing,shortness of breath,chest tightness and cough.The etiology of asthma has not been clearly studied,but it has been established that epigenetic and transcriptional changes caused by the interaction of genes and environmental factors play a very important role.According to immunology mechanism,asthma can be roughly divided into two categories:type 2 asthma and non-type 2 asthma.This project mainly studies allergic asthma related to type 2 immune response.The pathological features of asthma mainly include airway inflammation and airway remodeling.In allergic asthma,the synthesis,secretion,proliferation and migration of smooth muscle cells are enhanced,resulting in airway remodeling.The functional abnormality of airway smooth muscle is the main functional abnormality of asthma,and the inflammatory reaction will also interact with it to promote the development of asthma.Therefore,the study on the mechanism of airway smooth muscle cells in allergic asthma can provide a theoretical basis for avoiding and alleviating asthma.MicroRNAs(miRNAs,miRs)are(20-24 nucleotides)single-stranded non-coding RNAs.MiRNAs can inhibit the expression of target genes by binding to the 3’UTR of target genes and inhibiting the post-transcriptional level and translation level of target genes.Recent studies have shown that the expression of many miRNAs in asthma is associated with the occurrence and development of asthma.In this project,15 serum were collected from normal people,patients with mild asthma and patients with severe asthma for sequencing.The results showed that the expression levels of miR-17-5p,miR-107 and miR-140-5p were significantly down-regulated in patients with mild asthma and patients with severe asthma.The results of qPCR showed that the expressions of miR-17-5p,miR-107 and miR-140-5p in the serum of patients with mild asthma and patients with severe asthma were decreased,and the differences were statistically significant and consistent with the sequencing results.However,the mechanisms of miR-17-5p,miR-107 and miR-140-5p in the development of asthma need to be further investigated.This study established an asthma model with BABL/c mice and explored the mechanism of differentially expressed miRNAs in the asthma model and primary airway smooth muscle cells.In this study,we analyzed the sequencing results.It could be seen from the venn diagram that 91 miRNAs were co-up-regulated and 162 miRNAs were co-down-regulated in mild asthma and severe asthma compared with the control group.As can be seen from KEGG results,the target genes of these miRNAs were mainly related to tumor pathway,PI3K-Akt pathway,MAPK pathway and so on.Four databases including DIANA,miRDB,miRWalk and TragetScan were used for target gene prediction of differentially expressed miRNAs.By reading the literature,we screened out the target genes related to asthma from the intersection target genes,and verified them with dual-luciferase reporter assay.The results showed that MAPK8 and VCAN may be the target genes of miR-107.The results of qPCR showed that overexpressing of miR-107,the expression of target genes was down-regulated,while inhibiting the expression of miR-107,the expression of target genes was up-regulated.Next,a chronic asthma model was established by using BABL/c mice,and verified by pulmonary function tests,OVA specific lgE ELLSA,Giemsa staining of alveolar lavage fluid,HE staining,immunofluorescence and immunohistochemistry.The results of pulmonary function tests showed that the specific airway resistance increased significantly in the asthma group as the concentration of acetylcholine increased in inhalation.The serum levels of OVA specific lgE in asthmatic model mice were significantly increased,and the difference was statistically significant.The number of eosinophils in alveolar lavage fluid of asthmatic model mice was significantly increased.The results of HE staining showed that there were airway smooth muscle hyperplasia and inflammatory cell infiltration in the lungs of the asthmatic model mice.The expression of α-smooth muscle actin(α-SMA)was significantly increased by immunohistochemistry and immunofluorescence,indicating the presence of airway remodeling in asthmatic model mouses.Next,the primary airway smooth muscle cells were cultured to explore the role of miR-107 in the proliferation and migration of airway smooth muscle cells.The study showed that the expression of miR-107 was decreased and the ability of proliferation and migration was increased in primary cells of the asthma group compared with the control group.The overexpression of miR-107 inhibitored the proliferation and migration of airway smooth muscle cells.Finally,WB was used to identify downstream pathway proteins that played a role in asthma.To summarise,this study suggests that miR-107 may be a molecular biomarker for the occurrence and development of asthma.In addition,miR-107 plays an important role in the development of asthma.The expression of miR-107 was decreased and the ability of proliferation and migration was increased in primary airway smooth muscle cells of the asthma group mice,causing airway remodeling and promoting the development of asthma.The overexpression of miR-107 could inhibit the ability of proliferation and migration of airway smooth muscle cells.