Modulation of neutrophil extracellular traps release by Klebsiella pneumoniae in human neutrophils

DAIANA MARTIRE-GRECCO; FEDERICO BIRNBERG WEISS; VERÓNICA I. LANDONI; LUIS A. CASTILLO; GABRIELA C. FERNÁNDEZ

Mar del Plata

Congreso; LXVI Reunión Anual de la Sociedad Argentina de Inmunología; 2018

SAIC, SAI, SAFE

Klebsiella pneumoniae (Kp) carbapenemase (KPC)-producing bacteria are agroup of emerging highly drug-resistant Gram-negative bacilli, causinginfections associated with significant mortality, especially inimmunocompromised patients. Neutrophil (PMN)-mediated response isessential for fighting bacterial infections. The release of neutrophil extracellular traps (NETs) is a major immune mechanism intended to capture and destroy pathogens. Since the evasion of NETs may be an advantage for pathogen proliferation and dissemination, our aim was to investigate whether Kp was able to modulate NETs formation in human PMN. Therefore, we determine NETosis on purified PMN in response to a Kp-KPC-producer strain (Kp-KPC), and used Escherichia coli (Eco) for comparison. PMN-bacteria were incubated for 3 hours in a 1:10 ratio. NETs were observed and quantified using confocal microscopy after DNA and Elastase staining. Additionally, NETs-associated Myeloperoxidase (MPO) and DNA were released by nuclease treatment and measured in the supernatants of PMN-bacteria co-cultures. PMN failed to produce NETs when challenged with Kp-KPC, while Eco was a potent NET inducer (NETs area, µM 2 : Ctrl=1094±698, Kp-KPC=1480±845, Eco=20222±7854*; Released DNA, ng/mL: Ctrl=217±26, Kp-KPC=327±39, Eco=631±77*; Released MPO, O.D: Ctrl=0.13±0.02, Kp-KPC=0.11±0.03, Eco=0.96±0.15*, *p