BRUCELLA ABORTUS TRANSLOCATION OF THE PULMONARY EPITHELIUM AND ASSOCIATED INNATE IMMUNE RESPONSE

PAIVA ALONSO IVAN; MUÑOZ GONZÁLEZ FLORENCIA; FERRERO MARIANA CRISTINA; BALDI PABLO C

San Miguel de Tucumán

Congreso; LXVII Reunión Anual de al Sociedad Argentina de Inmunología; 2019

Sociedad Argentina de Inmunología

Pathogens have developed many strategies to cross epithelial barriers. We aimed to determine the mechanisms used by Brucella abortus to translocate the respiratory epithelial barrier, and to detect cytokines that could influence these mechanisms. Bronchial (16HBE14o-) or alveolar (A549) human epithelial cell lines were grown on Transwell inserts during 10-14 days to allow their polarization before apical infection (2 h, followed by short gentamicin treatment to kill extracellular bacteria, except in paracellular translocation assay). To evaluate transcellular migration, bronchial epithelia were infected, and at different days post-infection (p.i.) colony forming units (CFU) were determined in cell lysates and basolateral conditioned media (CM). To examine paracellular translocation, CM samples from infected alveolar epithelia were harvested to enumerate CFU. To assess Trojan Horse mechanism, infected or uninfected monocytes were added on top of infected or uninfected alveolar epithelia, and the number of monocytes in the basolateral CM was monitored. B. abortus invaded, replicated and induced a cytokine response (IL-6, IL-8 and MCP-1) in polarized bronchial epithelium, but was unable to transmigrate during 5d. Similarly, B. abortus could not cross paracellularly an alveolar epithelium. However, the pathogen could cross the alveolar barrier inside monocytes. This migration was enhanced when the epithelium was also infected, which correlated with increased IL-6, IL-8 and MCP-1 levels in apical and basolateral CM. In summary, B. abortus does not cross the respiratory epithelia by itself but can do it by the Trojan Horse mechanism aided by epithelial chemokines.