Figure 3. Calprotectin enhances S. aureus infection of the heart.

(A–C) S100a9^−/− (a9^−/−) or WT mice were fed high Mn, control, or low Mn diet and mock-infected or infected with S. aureus for 4 days. (A) MALDI-MS images of S100A8 from hearts of mice fed high Mn diet. Top, H&E stained section. Arrowheads indicate abscesses. Scale bar is 1 mm. Below, immunoblot for Sod1 (loading control) and S100A8 in hearts from WT mice. Images and blots are representative of three independent experiments. (B) Heart bacterial burdens recovered from WT and S100a9^−/− mice. N = 8 (control WT, control a9^−/−, high Mn a9^−/−), 5 (high Mn WT), 7 (low Mn WT), 9 (low Mn a9^−/−). Bars show median +/− interquartile range. (C) Survival of WT and S100a9^−/− mice following infection. N = 4. Survival is representative of three independent experiments. *P < 0.05, *** P < 0.001 by ANOVA with Tukey’s multiple comparisons test (B) or log-rank test (C). See also Figure S2