Fig. 4.
Acidosis exacerbates type III secretion system-dependent pulmonary damage during infection with P. aeruginosa. C57BL/6 mice were infected intratracheally with 3 × 106 CFU of WT or popB PA14 in an acidic or a basic pH buffer for 12 h. Bronchoalveolar lavage samples were collected, and inflammatory cytokine production and neutrophil recruitment were assessed by ELISA (A and B) or fluorescence-activated cell sorting and lung damage was determined by lactate dehydrogenase (LDH) release [arbitrary units (AU); C] or total protein concentration (D). Data are derived from ≥3 independent experiments (n ≥ 7 for all test groups). ***P ≤ 0.0005; **P ≤ 0.005; *P ≤ 0.05; ns, not significant [by 1-way ANOVA with Dunnett’s post hoc analysis (A–C) or unpaired Student’s t-test with Welch’s correction (D)].