B. pertussis compromises the epithelial barrier and survives in non-degradative intracellular compartments

BAROLI, CARLOS; GORGOJO, JUAN PABLO; BLANCÁ, BRUNO; MARTINA DEBANDI; RODRIGUEZ, MARIA EUGENIA

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

Bordetella pertussis (Bp) is the etiological agent of whooping cough, a reemerging respiratory tract disease. Current vaccines do not prevent transmission and epidemiological data indicates that vaccinated asymptomatic carriers are important reservoirs and constitute a source of transmission to vulnerable unvaccinated subjects. Recent studies suggest the existence of an intracellular niche of presistence inside host macrophages. We here investigated the potential role of the respiratory epithelial barrier in the infectious process and the eventual development of persistent infections. In binding assays Bp showed a clear tropism for tight junctions (TJ) of polarized 16HBE14o- cells as determined by fluorescence microscopy. This tropism seemed to be directed by the bacterial preference for basolateral membrane (BLM) mediated by FHA as addressed using a FHA defective strain. Our results further showed that wild type Bp but not an adenylate cyclase toxin (CyaA) deficient Bp strain disrupted TJ integrity as determined by confocal microscopy. This suggests that access of Bp to BLM in intact monolayers might be granted by the action of local high concentrations of CyaA released by the bacteria attached near TJ. The study of bacterial intracellular trafficking revealed that most internalized bacteria did not colocalize with lysosomal marker cathepsin D two days after infection suggesting that Bp avoids phagolysosomal fusion. Furthermore, we observed intracellular bacteria colocalizing with recycling pathway marker transferrin at this time, indicating that Bp might survive in non-degradative vesicles with access to nutrients. Accordingly, antibiotic protection assays showed high intracellular survival levels over the time post infection. Taken together, these results show that Bp can compromise epithelial barrier, invade cells and persist in intracellular location in the respiratory epithelium, pointing out its potential relevance as another persistence niche.