Bronchial smooth muscle of severe asthmatic patients decreases rhinovirus replication within the epithelium through a CCL-20/PKR/eIF2-a dependent pathway

Abstract

Rhinovirus (RV) infections of bronchial epithelium (BE) is implicated in the vast majority of exacerbations in severe asthma. Moreover, bronchial remodeling in severe asthma is characterized by an increased bronchial smooth muscle (BSM) mass. However, the role of asthmatic BSM in RV infections of the BE has never been demonstrated. We thus hypothesized that asthmatic BSM increased both BE susceptibility and response to RV infection. We designed transcriptomic and proteomic approaches both in vitro using co-culture model of BE with BSM cells and ex vivo using patient biopsy from 19 severe asthmatic patients and 37 non-asthmatic subjects. RV particles number within BE cells was measured using digital PCR. Cytokines concentrations were assessed using ELISA assays. PKR pathway was analyzed by western blotting. We found an increased RV replication in BE co-cultured with asthmatic BSM cells compared to non-asthmatic BSM cells. Large scaled proteomic and transcriptomic analysis highlighted CCL-20 increased expression in asthmatic BSM cells. Blocking CCL-20 in the co-culture supernatant with asthmatic BSM cells reduced the number of RV particles within the BE cells. Moreover, we showed a decreased level of PKR signaling pathway, including activated forms of PKR and phosphorylation of eIF2-α. In conclusion, our results clearly demonstrated that asthmatic BSM cells increased the BE response to RV, through an increased CCL-20 production, which in turn, down-regulate the PKR pathway response. Our study highlight CCL-20 as a new therapeutic target for RV-induced exacerbation in severe asthmatic patients.