CP enhances the activity of the SaeRS TCS and cytokine production in mice.

<p><b>(A)</b> The activity of the SaeRS TCS in C57BL/6 (WT) and C57BL/6 S100A9^-/- (A9^-/-) mice. Mice were infected with <i>S</i>. <i>aureus</i> (2 × 10⁸ cfu) by peritoneal injection, and peritoneal fluid was acquired at the indicated time points. After being separated by centrifugation (200 ×<i>g</i>), the GFP expression of <i>S</i>. <i>aureus</i> in supernatant (host cell-free) or in pellet (host cell-associated) was measured by flow cytometry (top panel), where the gray color represents GFP expression from pCL-<i>gfp</i>. The quantification results are shown in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005026#ppat.1005026.s005" target="_blank">S5 Fig</a>. <b>(B)</b> The effect of CP on the expression of select genes. <b>(C)</b> The production of proinflammatory cytokines in wild type (WT) and S100A9^-/- (A9^-/-) mice upon infection with <i>S</i>. <i>aureus</i> USA300 (USA) or the <i>sae</i> deletion mutant (Δ<i>sae</i>). At the time points indicated, mice were sacrificed and the concentrations of proinflammatory cytokines in peritoneal fluids were determined by ELISA. The data are from three pooled mice per genotype and represent three independent experiments. Error bars indicate standard error of the mean. -, no bacteria. Statistical significance was assessed by <i>t</i>-test. * <i>p</i> < 0.05; ** <i>p</i> < 0.01; *** <i>p</i> < 0.001