Rhinovirus C15 Attenuates Relaxation and cAMP Production in Human Airways and Smooth Muscle.

Rhinoviruses (RVs) evoke as many as 85% of acute asthma exacerbations in children and 50% in adults and can induce airway hyperresponsiveness and decrease efficacy of current therapeutics to provide symptom relief. Using human precision-cut lung slices (hPCLSs), primary human air-liquid interface-differentiated airway epithelial cells (HAECs), and human airway smooth muscle (HASM) as preclinical experimental models, we demonstrated that RV-C15 attenuates agonist-induced bronchodilation. Specifically, airway relaxation to formoterol and cholera toxin, but not forskolin (Fsk), was attenuated following hPCLS exposure to RV-C15. In isolated HASM cells, exposure to conditioned media from RV-exposed HAECs decreased cellular relaxation in response to isoproterenol and prostaglandin E2, but not Fsk. Additionally, cAMP generation elicited by formoterol and isoproterenol, but not Fsk, was attenuated following HASM exposure to RV-C15-conditioned HAEC media. HASM exposure to RV-C15-conditioned HAEC media modulated expression of components of relaxation pathways, specifically GNAI1 and GRK2. Strikingly, similar to exposure to intact RV-C15, hPCLS exposed to UV-inactivated RV-C15 showed markedly attenuated airway relaxation in response to formoterol, suggesting that the mechanism(s) of RV-C15-mediated loss of bronchodilation is independent of virus replication pathways. Further studies are warranted to identify soluble factor(s) regulating the epithelial-driven smooth muscle loss of ß2-adrenergic receptor function.

Airway smooth muscle and airway hyperresponsiveness in asthma: mechanisms of airway smooth muscle dysfunction.

Airway smooth muscle plays a pivotal role in modulating bronchomotor tone. Modulation of contractile and relaxation signaling is critical to alleviate the airway hyperresponsiveness (AHR) associated with asthma. Emerging studies examining the phenotype of ASM in the context of asthma provide rich avenues to develop more effective therapeutics to attenuate the AHR associated with the disease.