Fig 8. Time course of mean serum inflammatory cytokine concentrations during experiment.

Serum concentrations of interleukin (IL)-8 (Fig 8A) and tumor necrosis factor (TNF)-α (Fig 8B) measured by enzyme-linked immune-sorbent assay at baseline, just before intra-tracheal instillation of 10⁹ CFU of Staphylococcus aureus, in the spontaneously breathing (SB+S.aureus) and the mechanically ventilated (MV+S.aureus) animals, and then 1, 2, 4, 8, 12, 18 and 24 hours after instillation (n = 15). Significant changes over time in each group were assessed by repeated-measures analysis of variance followed by the post hoc Bonferroni multiple comparison test when significance was reached. *denotes variations with time significantly different between MV groups versus SB groups; ns: not significant. CFU: colony forming unit. (A) repeated-measures ANOVA mean difference = -69.35 [-141.7 to +2.969] 95% CI; p = ns). (B) repeated-measures ANOVA mean difference = -56.11 [-104.7 to -7.547] 95% CI; p = 0.010).