Fig. 4
Ligand-specific Mac-1 inhibition improves sterile and bacterial sepsis by preventing excessive inflammation and enhanced bacterial clearance. A systemic inflammatory response syndrome (SIRS) induced in C57Bl/6 mice by an i.p. injection of 20μg LPS (0111:B4). a Leukocyte accumulation in the peritoneal cavity was characterized with a 15-parameter panel in flow cytometry. b Macrophages were sub-divided into F4/80low and F4/80high. c Relative myeloid cell composition in the peritoneal cavity was compared in untreated mice (left cake diagram), after LPS injection (LPS), and after surgical induction of a cecal ligation and puncture (CLP) polymicrobial sepsis. d Male, 8-week-old C57Bl/6 mice were injected with 20 μg LPS (0111:B4) and 50 μg of the indicated antibody clones. After 20 h, myeloid cell populations were quantified in the peritoneal cavity (expressed as % of IgG-treated animals). e Myeloid cell populations in the peritoneal cavity 20 h after surgical induction of a CLP sepsis in male, 8-week-old C57Bl/6 mice. 1 h before surgery 50μg of the indicated antibodies, including anti-mouse Mac-1 (M1/70), were injected. f Limulus assay in the peritoneal cavity and plasma to detect bacterial LPS titers after CLP. g, h Uptake of Alexa-488 labeled E. coli into macrophages and i binding of the complement factor iC3b in vitro after pre-incubation with the indicated antibody clones. j CLP was induced in male, 8-week-old C57Bl/6 mice. To assess whether treatment with Mac-1 antibody clones (50 μg) affects survival, mice were treated by intraperitoneal injection with either anti-Mac-1 (clone M1/70) or anti-M7 Fab preparations at −1, 48, and 96 h after induction of CLP sepsis. Relative survival was calculated and displayed as Kaplan–Maier survival curve. Error bars indicate mean ± SEM. Statistical significance was assessed by two-sided, unpaired T-test (d, e, f, h, i) against IgG or a Log-rank (Mantel-Cox) test (j). *P < 0.05, **P < 0.01, ***P < 0.001. Data are the result of N ≥ 9 mice per group (c–f), N = 5 mice per group (h, i), or N = 15 mice per group (j). Representative FACS plots are shown in (a, b, g)
