Macrophage-derived LTB4 promotes abscess formation and clearance of Staphylococcus aureus skin infection in mice
Fig 4
LTB4 is required for neutrophil association in the abscess.
(A) Heat map of proteins involved in inflammatory immune response and resolution in WT and BLT1-/- mice infected with MRSA at day 1 and day 9 after infection measured using bead array multiplex. Proteins are listed on right-hand y-axis; grouped alphabetically in clades. Red indicates higher abundance whereas blue represents lower abundance. Each column for each condition represents a technical replicate (n = 4-5/group). B) Skin biopsy sections from WT, BLT1-/-, 5-LO-/-, and 5-LO-/- mice + LTB4 ointment were stained with anti-Ly6G/C antibody as described in the Material and Methods. Top panels are 40 X, and bottom panels are 400 X magnification. Neutrophil staining is shown in brown and counterstained in blue. C) Detection of Ly6G positive cells in the skin biopsies of mice infected and treated with the vehicle control or the ointment containing 0.001% BLT1 antagonist for 24 h using FACS analysis. D) Still frames of the intravital imaging from the EGFP-LysM mice infected with MRSA and treated with ointments containing vehicle control (untreated), 3.37 ng LTB4 ointment, or 0.001% BLT1 antagonist (U75302). After 24 hours, the mice were imaged by two-photon intravital microscopy for 30 minutes. E) Determination of the swarm size in WT EGFP-LysM mice treated or not with the LTB4 ointment using image J as described in the Material and Methods. F) Quantifications and track paths of mice represented in (C) that show the median velocity of the GFP+ cells. Track displacements of GFP+ cells and ratios of displacement/track durations were measured using FIJI (ImageJ) Trackpath plugin software and analyses were as described in the Material and Methods. Data are the mean ± SEM of 1000+ GFP+ cells representative of 3–4 mice. ****p < 0.0001 vs. untreated. White arrows indicate swarming.