Macrophage-derived LTB4 promotes abscess formation and clearance of Staphylococcus aureus skin infection in mice
Fig 5
Skin macrophages are necessary for LTB4 production and host defenses during MRSA skin infection.
A) Skin biopsy sections from WT, BLT1-/-, 5-LO-/-, and 5-LO-/- plus the LTB4 ointment treated mice stained with the anti-F4/80 antibody as described in Material and Methods. The top panels are 40 X, the middle panels are 400 X, and the bottom panels are 1000 X magnification. Macrophages stained brown, and the counterstain is blue. Black arrows indicate macrophages and the black dashed box is the amplified region. Images are representative of 3–5 mice. B) Depletion of skin macrophages in MMDTR mice were PBS-treated or DT-treated and infected with MRSA by subcutaneous injection. C) Percentages of Ly6G+ cells in MMDTR mice treated or not treated with DT, followed by MRSA infection for 24 hours, and examined by FACS analyses. D) LTB4 production in the skin of MMDTR treated or not treated with DT mice, followed by infection at the indicated time points as detected by EIA. E and F) Production of CXCL1 (E) and CCL4 (F) in the skin biopsies from MMDTR mice treated or not treated with DT, followed by MRSA skin infection for the indicated time points as detected by ELISA. G) Slides were stained using DAPI (blue), mCherry for macrophages (red), and FITC-labeled anti-Ly6G antibody (green). Images shown are at 200 X magnification and are representative of 3–5 mice/group. White arrows indicate mCherry+ stained macrophages. H) Bacterial loads of MMDTR mice treated or not treated with DT, infected with MRSA, and treated with LTB4 ointment for 24 hours as measured by CFU counts/mg tissue. I) Lesion sizes of MMDTR mice treated as in (F) and measured 24 hours after infection. Data are the mean ± SEM of 3–8 mice. *p < 0.05 vs. naïve. #p < 0.05 vs PBS-treated mice.