Fig 9. Inflammatory cytokines in whole blood stimulated ex vivo by either Pam₃CSK₄, or S. aureus.

Interleukin (IL)-8 and tumor necrosis factor (TNF)-α levels in total blood stimulated ex vivo by Pam3CysSerLys4 (Pam₃CSK₄) (Fig 9A) or Staphylococcus aureus (Fig 9B) in either spontaneously breathing (SB, n = 7) rabbits or animals subjected to mild-stretch mechanical ventilation (MV, n = 5), with or without the anti-toll-like receptor (TLR)2 monoclonal antibody (Mab) T2.5. Interleukin-8 levels were not significantly greater in blood obtained from rabbits under MV than in controls but the difference reached statistical significance after stimulation by Pam₃CSK₄ and S. aureus as well. Similarly, TNF-α levels were not significantly higher in blood taken from MV animals than in blood from SB animals. In contrast, Pam₃CSK₄ stimulation led to the release of significantly larger amounts of TNF-α in the MV than in the SB group, as did S. aureus stimulation. Although TLR2 blockade by T2.5 Mab did not abrogate the release of inflammatory mediators by the whole blood obtained from either SB or MV animals after Pam₃CSK₄ stimulation, TNF-α but not IL-8 release reached baseline values when Mab was added to media prior to S. aureus stimulation. * denotes p<0.05 between SB and MV animals. (A) IL-8 Controls: SB versus (vs) MV p = 0.010, Mann-Whitney U test, two-tailed. Pam₃CSK₄ SB vs MV p = 0.010, Mann-Whitney U test, two-tailed. Pam₃CSK₄ + T2.5 SB vs MV p = 0.002, Mann-Whitney U test, two-tailed. Pam₃CSK₄ + IgG1k SB vs MV p = 0.002, Mann-Whitney U test, two-tailed. TNF-α: Controls SB vs MV p = 0.075, Mann-Whitney U test, two-tailed. Pam₃CSK₄ SB vs MV p = 0.030, Mann-Whitney U test, two-tailed. Pam₃CSK₄ + T2.5 SB vs MV p = 0.002, Mann-Whitney U test, two-tailed. Pam₃CSK₄ + IgG1k SB vs MV p = 0.030, Mann-Whitney U test, two-tailed. (B) IL-8: Controls SB vs MV p = 0.010, Mann-Whitney U test, two-tailed. S. aureus SB vs MV p = 0.029, Mann-Whitney U test, two-tailed. S. aureus + T2.5 SB vs MV p = 0.029, Mann-Whitney U test, two-tailed. S. aureus + IgG1k SB vs MV p = 0.200, Mann-Whitney U test, two-tailed. TNF-α Controls SB vs MV p = 0.075, Mann-Whitney U test, two-tailed. S. aureus SB vs MV p = 0.057, Mann-Whitney U test, two-tailed. S. aureus + T2.5 SB vs MV p = 0.343, Mann-Whitney U test, two-tailed. S. aureus + IgG1k SB vs MV p = 0.657, Mann-Whitney U test, two-tailed.