The Role And Mechanism Of MiRNA-30a-3p In Airway Eosinophilic Inflammation In Asthma

Background:Type 2-high asthma is a prominent endotype of asthma which is characterized by airway eosinophilic inflammation.Airway epithelial cells play critical roles in asthma pathogenesis.Our previous miRNA profiling data showed that miRNA-30a-3p was downregulated in bronchial epithelial cells from asthma patients.We hypothesize that miRNA-30a-3p plays a role in asthma airway inflammation.Methods:Asthma patients（n=51）and healthy controls（n=16）were recruited.Mi RNA‐30a-3p expression of bronchial brushings was measured,and the correlation between epithelial miRNA‐30a-3p expression and airway eosinophilia was analyzed.Fluorescent in situ hybridization was performed on bronchial biopsies to assess localization of miRNA-30a-3p.Dual-luciferase reporter assay was performed to verify that RUNX2 is a target gene of miRNA-30a-3p.Whether RUNX2 was a promoter of HMGB1 was examined by using Ch IP-PCR and luciferase reporter assay.The role of miRNA‐30a-3p was explored using a murine model of allergic airway inflammation.Results:There was no difference in sex,age and BMI between the two groups of the control and asthma.The proportion of eosinophils in the sputum and biopsy area,and Fe NO in the bronchial asthma group were obviously higher than control group.While the FEV₁%predicted and PD₂₀ value of the bronchial asthma group were less than control group.Mi RNA-30a-3p expression was significantly decreased in bronchial brushings of asthma patients compared to control subjects.Moreover,epithelial miRNA-30a-3p expression was negatively correlated with parameters reflecting airway eosinophilia including eosinophils in induced sputum（r=-0.362,P=0.009）and bronchial biopsies（r=-0.473,P=0.000 5）,Fe NO（r=-0.493,P=0.000 2）,and Three-gene-mean（r=-0.594,P<0.000 1）in asthma patients.Mi RNA-30a-3p was found to target RUNX2.Furthermore,RUNX2 was found to bind to the promoter of HMGB1 and upregulate HMGB1 expression.Intriguingly,airway overexpression of mmu-miRNA-30a-3p suppressed Runx2 and Hmgb1 expression,and alleviated airway eosinophilia in a mouse model of allergic airway inflammation disease.Conclusion:In bronchial brushings of asthma,miRNA-30a-3p was significantly decreased.Mi RNA-30a-3p was mainly expressed in the cytoplasmic parts of the airway epithelial cells.The expression of miRNA-30a-3p negatively correlated with the markers of eosinophilic inflammation in asthma.Epithelial miRNA-30a-3p suppresses airway eosinophilia by targeting RUNX2/HMGB1 axis in asthma.