Disruption of goat airway epithelial barrier function by caprine parainfluenza virus type 3 infection in an ALI model.

Abstract

The respiratory epithelium acts as the airway's first physical barrier against invading pathogens, mainly relying on mucociliary clearance (MCC) and apical junctional complexes (tight junctions/TJs and adherens junctions/AJs) for barrier function. Primary airway epithelial cells cultured in the air-liquid interface (ALI) system can well mimic these characteristics in vitro. This study established and characterized well-differentiated ALI-cultured goat airway epithelial cells (ALI-GAECs), and developed a CPIV3 infection model therein, verifying the apical infection and release of CPIV3 in ALI-GAECs. CPIV3 infection impaired the barrier function of ALI-GAECs, as reflected by decreased trans-epithelial electrical resistance (TEER), increased FITC-Dextran permeability, and reorganization of the ZO-1 and F-actin meshwork. Mechanistically, RT-qPCR and Western blot analyses demonstrated that CPIV3 downregulated major TJ proteins (ZO-1, occludin, claudin-1) while upregulated the expression of proinflammatory cytokines (TNF-α, IL-1β, IL-4, IL-6). The NF-κB signaling pathway, but not the MAPK pathways, was activated upon viral infection. Treatment with the NF-κB inhibitor BAY 11-7082 partially restored the expression of TJ proteins and proinflammatory cytokines. Collectively, the activation of the NF-κB pathway and subsequent production of proinflammatory cytokines is responsible for CPIV3-induced TJ disruption. In addition, the developed ALI-GAECs model provides a valuable in vitro tool for investigating the pathogenesis of CPIV3 and other caprine respiratory pathogens.