Elimination of Pseudomonas aeruginosa through efferocytosis

MARIA VICTORIA PEPE; DARIO CAPASSO; JESSICA ROSSELLO; PAOLA LEPANTO; PAULA ARIAS; WALTER SPERAT; . ARLINET KIERBEL, AMA GASSAMA-DIAGNE, CLAUDIA ROCHA, KEITH MOSTOV, AND JOANNE ENGEL

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Pseudomonas aeruginosa (PA) is an environmental bacterium that is capable of causing acute infections in individuals with wounds and chronic infections in Cystic Fibrosis (CF) patients. For opportunistic pathogens such as PA, the mucosal barrier represents a formidable challenge for colonization and bacterial-mediated damage. Infections develop only in patients with altered epithelial cell barriers. In CF patients the respiratory tract is characterized by the presence of hyper-viscous mucus, robust airway inflammation and accumulation of apoptotic cells. We have recently reported that PA interacts with polarized epithelial barrier adhering as aggregates at very localized spots of the apical surface. We demonstrated that aggregates are formed in situ and that they can be rapidly internalized into epithelial cells in a Lyn-PI3K dependent manner.In this study we show those localized spots where PA aggregates correspond to sites of multi-cellular junctions formed by four or more cells. We further show that in those sites PA attaches to extruded apoptotic cells or cell bodies. PA is then internalized through engulfment of apoptotic cells (a process called ?efferocytosis?) by surrounding epithelial cells. Inside these cells bacteria inhabit, along with apoptotic cell debris, an efferocytic phagosome that acquires lysosomal features. PA is eliminated intracellularly upon 24 hours.