Pulmonary bacterial clearance in lipopolysaccharide-induced tolerance vs. shock murine models

RODRIGUEZ-RODRIGUES N; MARTIRE-GRECO D; LANDONI V.I; CHIRELLA P.; SCHIERLOH P.; REARTE B.; MEISS R; ISTURIZ M.A; FERNANDEZ G.C.

Mar del Plata

Congreso; LIX REUNIÓN CIENTÍFICA ANUAL Sociedad Argentina de Investigación Clínica. LXII REUNIÓN ANUAL Sociedad Argentina de Inmunología; 2014

Repeated inoculation of bacterial lipopolysaccharide (LPS) in mice generates a refractory state, where animals survive lethal doses of LPS and have low amounts of LPS-induced TNF. This state is also associated with defects in antibody responses. Our aim was to compare how the exposure to LPS affects pulmonary bacterial clearance as a measure of innate immune function. For this purpose, we used two models of LPS exposure. In the LPS-tolerance model, tolerance was induced by daily i.v. injections of increasing doses of LPS (5-100 µg/day/mouse) for 7 days. In the LPS-shock model a single high dose of LPS (50 µg/mouse) was administered i.v. Then the animals were challenged intratracheally with intestinal bacteria (5x106 CFU) and the number of remaining bacteria in the lung or bronchoalveolar lavage (BAL) was evaluated 4h post-infection on McConkey agar plates. In the LPS-tolerance model the bacterial clearance was higher compared to Control mice (Total CFU. Lung: C= 3,94x106 ± 1,02x106, Tol= 1,34x106 ± 0,90x106. BAL: C= 5,85x105 ± 0,57x105, Tol= 6,66x104 ± 2,22x104, p