Asthmatic Bronchial Smooth Muscle Increases CCL5-Dependent Monocyte Migration in Response to Rhinovirus-Infected Epithelium

Asthma exacerbations, a major concern in therapeutic strategies, are most commonly triggered by viral respiratory infections, particularly with human rhinovirus (HRV). Infection of bronchial epithelial (BE) cells by HRV triggers inflammation, notably monocyte recruitment. The increase of bronchial smooth muscle (BSM) mass in asthma, a hallmark of bronchial remodeling, is associated with the annual rate of exacerbations. The aim of the present study was to assess whether or not BSM could increase monocyte migration induced by HRV-infected BE. We used an advanced in vitro model of co-culture of human BE cells in air-liquid interface with human BSM cells from control and asthmatic patients. Inflammation triggered by HRV infection (HRV-16, MOI 0.1, 1 h) was assessed at 24 h with transcriptomic analysis and multiplex ELISA. In vitro CD14⁺ monocyte migration was evaluated with modified Boyden chamber. Results showed that HRV-induced monocyte migration was substantially increased in the co-culture model with asthmatic BSM, compared with control BSM. Furthermore, the well-known monocyte migration chemokine, CCL2, was not involved in this increased migration. However, we demonstrated that CCL5 was further increased in the asthmatic BSM co-culture and that anti-CCL5 blocking antibody significantly decreased monocyte migration induced by HRV-infected BE. Taken together, our findings highlight a new role of BSM cells in HRV-induced inflammation and provide new insights in mucosal immunology which may open new opportunities for prevention and/or treatment of asthma exacerbation.

Expansion of Airway Basal Cells and Generation of Polarized Epithelium

Airway basal stem cells are the progenitor cells within the airway that exhibit the capacity to self-renew and give rise to multiple types of differentiated airway epithelial cells. This stem cell-derived epithelium displays organized architecture with functional attributes of the airway mucosa. A protocol has been developed to culture and expand human airway basal stem cells while preserving their stem cell properties and capacity for subsequent mucociliary differentiation. This achievement presents a previously unrealized opportunity to maintain a durable supply of progenitor cells derived from healthy donors to differentiate into human primary airway epithelium for cellular and molecular-based studies. Further, basal stem cells can be harvested from patients with a specific airway disease, such as cystic fibrosis, enabling investigation of potentially altered behavior of disease-specific cells in the appropriate context of the airway mucosa. Here we describe, in detail, a protocol for the serial expansion of airway basal stem cells to enable the generation of nearly unlimited airway basal cells that can be stored and readily available for subsequent culturing and differentiation. In addition, we describe culturing and differentiation of airway basal stem cells on permeable transwell filters at air-liquid interface to create functional mucociliary pseudostratified polarized airway epithelial mucosa.