Macrophage-derived LTB4 promotes abscess formation and clearance of Staphylococcus aureus skin infection in mice
Fig 6
LTB4 promotes NADPH oxidase-mediated killing of MRSA.
A) Determination of bacterial killing in peritoneal macrophages and bone marrow-derived neutrophils from WT and BLT1-/- mice as described in the Material and Methods. B) (left) Determination of reactive oxygen species (ROS) production in macrophages from WT mice treated or not treated with the BLT1 antagonist, followed by challenge with MRSA for 60 minutes. (Right) Relative fluorescence units (RFU) levels of CellRox positive macrophages treated with vehicle control, LTB4, and BLT1 antagonist, followed by MRSA infection for 60 minutes. The RFU were determined as described in the Material and Methods. C) Mean fluorescence intensity (MFI) levels of CellRox positive bone marrow-derived neutrophils treated with vehicle control and BLT1 antagonist, followed by MRSA infection for 60 minutes. The MFI was determined as described in the Material and Methods. D) WT or gp91phox-/- mice were infected with MRSA via s.c. and treated topically daily with vehicle-control ointment, apocynin, LTB4 ointment, or apocynin + LTB4 combination ointment. Infection areas were measured 24 hours after infection, and the affected areas were measured as described in the Material and Methods. E) Bacterial loads of WT and Gp91phox-/- mice treated as in (D) and CFU were determined 24 hours after infection as described in the Material and Methods. F) H&E staining of mice treated and infected as in (D). The top panels are 4 X, and the bottom panels are 40 X magnification. Data are the mean ± SEM of 8–15 mice. *p < 0.05 vs. WT. White arrows indicate abscess edges. All abbreviations are defined in Figs 1 and 2 legends.