Fig. 5

Effect of depletion of IKKβ in intestine on lung against P. aeruginosa pneumonia-induced bacterial counts and MPO activity of the lung. a Intramuscular combined antibiotic was given to Vil-Cre/Ikkβ^F/Δ or Ikkβ^F/Δ mice for 6 days. The trachea of mice was surgically exposed and 50 μl (1.0 × 10⁷ CFU P. aeruginosa) were instilled via an angiocatheter through the trachea to induce P. aeruginosa pneumonia and neutrophil infiltration in the lungs was examined. P. aeruginosa intra-tracheal injection induced a significant increase of bacterial counts in the lung in Vil-Cre/Ikkβ^F/Δ mice as compared with that in Ikkβ^F/Δ mice. Antibiotic pretreatment significantly increased twofold of P. aeruginosa-induced bacterial counts in the lung in Ikkβ^F/Δ mice. Data are presented as mean ± SEM. b Antibiotics treatment significantly increased twofold of P. aeruginosa-induced MPO activity of lung in Ikkβ^F/Δ as compared with the control group. Antibiotic pretreatment did not increase P. aeruginosa-induced MPO activity in the lung in Vil-Cre/Ikkβ^F/Δ mice. Lung tissues were weighed and homogenized in 50 mM potassium phosphate buffer (pH 6.0) with 0.5% hexadecyltrimethyl- ammonium bromide. Homogenates were centrifuged at 9500×g, 4 °C for for 10 min. An aliquot (60 μl) of supernatants was added to 939 μl of potassium phosphate buffer with 16.7 mg/ml of O-dianisidine and 0.5% hydrogen peroxide. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01