B. parapertussis adenylate cyclase toxin plays a key role on respiratory epithelial cell infection by subverting the epithelial barrier function

GORGOJO, JUAN PABLO; CARRICA, MARIELA; BAROLI, CARLOS; VALDEZ, HUGO; RODRIGUEZ, MARIA EUGENIA

Buenos Aires

Congreso; Reunión de Sociedades de Biociencias 2021. LXVI Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC). LXIX Reunión Anual de la Sociedad Argentina de Inmunología (SAI). LIII Reunión Anual de la Asociación Argentina de Farmacología Experim; 2021

Sociedad Argentina de Inmunología

B. parapertussis (Bpp) is one of the causative agents of whooping cough and a key factor contributing to its reemergence. The development of improved strategies to control it requires identifying the mechanism of persistence within the host to eventually eradicate the carriage. We previously found that an intracellular stage in epithelial cell might be important for its persistence. In that work we found a tropism of Bpp for tight junctions (TJ). Like for other pathogens, this might indicate the existence of a mechanism to subvert epithelial barrier function. We here investigated the role of the barrier function during Bpp infection. To this end we used the 16HBE14o- bronchial cell line that polarize in vitro and form TJ . Two experimental models were used. A fully 7-day polarized confluent monolayer in which apical (AP) and basolateral (BL) components are largely separated by TJ and a 1-day confluent monolayer model, which lacks of TJ and hence barrier function. Cells were infected with Bpp and the outcome of this interaction was evaluated. Microscopy analysis showed that 6 h after infection the attachment and internalization were higher in the 1-day confluent monolayer than in the 7-day model, indicating that the infection efficiency increased when barrier function are absent and Bpp access BL components. We further evaluated how Bpp accesses the BL components in a monolayer with intact TJ. Microscopy analysis showed that early after infection, Bpp adheres to and progressively disrupts the TJ in a CyaA toxin dependent way, suggesting that Bpp might access the BL components by subverting epithelial barrier. Accordingly, a CyaA defective mutant showed a reduced efficiency to access the intracellular location in a 7-day polarized model with intact TJ. These results suggest that CyaA-mediated epithelial barrier disruption might grant Bpp access to the intracellular location of epithelial cells and/or the possibility to disseminate to underlying tissues.