Macrophage-derived LTB4 promotes abscess formation and clearance of Staphylococcus aureus skin infection in mice
Fig 2
LTB4/BLT1 axis is essential to control MRSA skin infections.
A) The infection area was measured every other day for 9 days in wild-type (WT) C57BL/6 and BLT1-/- mice infected subcutaneously (s.c.) with MRSA and then treated daily or not treated with BLT1 antagonist U75302 (U7) or vehicle control. B) Bacterial loads (CFU counts) determined at days 1 and 9 after MRSA skin infection in C57BL/6, 5-LO-/-, BLT1-/-, and BLT1 antagonist-treated mice. C) Infection areas were determined as in (A) in the C57BL/6, and 5-LO-/- mice treated or not treated daily with LTB4 ointment. D) Bacterial load in the infected skin determined as in (B) in WT and 5-LO-/- mice treated or not treated with LTB4 ointment. E) Gram staining of Skin biopsies collected at day 1 post-MRSA skin infection from WT, BLT1-/-, 5-LO-/-, and 5-LO-/- mice treated topically with 3.37 × 10−6% LTB4 ointment. Gram staining to label gram-positive bacteria is shown in purple/brown. Top panels are 40 X, middle panels are 100 X, and bottom panels are 400 X magnification Insets represent 1000 X magnification. Black arrows indicate MRSA clusters. Images are representative of 3–5 mice. F) H&E stains from mice treated as in (E) and shown at 40 X (upper) and 100 X magnification. G) Thickness of Masson’s trichrome blue positive layer surrounding the abscess was measured with ImageJ software. In all cases, data represent the mean ± SEM from 3–4 mice. *p < 0.05 vs. WT. #p < 0.05 vs. 5-LO-/- treated with vehicle-control ointment.