Airway Epithelial-derived Exosomes Induce Asthma Exacerbations After RSV Infection

Asthma exacerbation refers to the progressive exacerbation of clinical symptoms in asthma patients after infection with allergens such as viruses,such as dyspnea,coughing and wheezing,etc.Corticosteroids have limited effects on the treatment and control of asthma exacerbation.Respiratory syncytial virus(RSV)is a common predisposing factor for asthma exacerbations.After RSV infection,the barrier function of airway epithelial cells is destroyed.Then,airway epithelial cells release a large number of inflammatory cytokines to activate immune cell population,thereby exacerbating the pulmonary inflammatory response in stable asthma patients.It has been confirmed that airway epithelial cells can induce the occurrence and development of lung inflammation by secreting exosomes after allergen stress,which is involved in the information exchange between epithelial cells and immune cells.However,the role of airway epithelial cell-derived exosomes in asthma exacerbations after RSV infection remains obscure.Objective:This study was designed to investigate the role of airway epithelial cell-derived exosomes in asthma exacerbation after RSV infection.Methods:(1)Asthma exacerbation model were constructed by HDM stress combined with RSV infection.Exosomes was blocked though injection of exosome inhibitor GW4869 in vivo.The degree of pulmonary inflammatory was detected by histopathological staining.The classification of inflammatory cells was assessed by flow cytometry and qPCR assays for inflammatory factors.(2)Exosomes derived from airway epithelial cells was purified and identified by ultracentrifugation,transmission electron microscopy,and nanofluidic flow.The proliferation of T lymphocyte was assessed by Ed U proliferation and CCK-8 assays.The differentiation of T lymphocyte was assessed by flow cytometry,ELISA and qPCR detection of inflammatory factors.(3)The differential microRNAs related to inflammation in exosomes of airway epithelial cells was screened and validated by qPCR in vitro.Then,inflammation-related microRNA was blocked by the specific inhibitor in vivo.Pulmonary inflammation was detected by HE staining,flow cytometry and activation of T lymphocytes was detected by ELISA and qPCR detection of inflammatory factors.Results:(1)Asthma exacerbation model was successfully established by HDM stress combined with RSV infection.Blockade of exosomes by GW4869 can significantly reduce the Th2-type inflammatory response in the lungs of mice with acute exacerbation of asthma after RSV infection.(2)The airway epithelial cell-derived exosomes were purified successfully.After stress of HDM combined with RSV,the epithelialderived exosomes induced the proliferation and Th2-type differentiation of T lymphocytes.(3)After stress of HDM combined with RSV,the expression of microRNA-155-5p(miR-155-5p)was significantly up-regulated in epithelial cell-derived exosomes.Targeted blockade of miR-155-5p in exosomes can effectively block the proliferation and differentiation of T lymphocytes.Blockade of miR-155-5p by intranasal instillation of specific inhibitor can significantly inhibit Th2-type inflammation in the lungs of asthma exacerbation model after.Conclusion:(1)Exosomes are involved in inducing the occurrence and development of pulmonary inflammation in asthma exacerbation model after RSV infection.(2)After stress of HDM combined with RSV,airway epithelial cellderived exosomes are involved in the regulation of proliferation and differentiation of T lymphocytes.(3)After RSV infection,airway epithelial cell-derived exosomes promote the proliferation and differentiation of Th2 inflammation by transporting upregulating miR-155-5p,which further induced acute exacerbation of asthma.