Figure 4

Metformin diminished LPS-induced inhibition of neutrophil chemotaxis. (A) Neutrophils were treated with metformin (met; 0 or 500 µmol/L) for 90 min and then LPS (0 or 300 ng/mL) for 60 min, or cells were first treated with LPS (300 ng/mL) for 60 min followed by inclusion of metformin (500 µmol/L) in the cultures for an additional 90 min. Neutrophil chemotaxis was then examined. Means ± SD, n = 3, *P < 0.05, **P < 0.01 compared with neutrophils treated with LPS alone. (B) Representative images show direction and distance (length of arrows) passed by the neutrophils a pretreated with metformin, LPS, compound C or combination of metformin and LPS. Panel (C) shows neutrophil velocity. Mean ± SEM, n ≥ 20, *P < 0.05, **P < 0.01 compared with control, *P < 0.001 compared with metformin and §P < 0.001 compared with LPS alone. Large arrow indicates direction to W-peptide. (D, E). Metformin stimulates, whereas compound C diminishes neutrophil chemotaxis in vivo. Panel (D) shows time line administration of metformin (125 mg/kg; IP), compound C (3 mg/kg; IP), PBS (200 µL; IP) or W-peptide (0.43 mg/kg; IP) followed by acquisition of peritoneal neutrophils. Panel (E) shows amount of peritoneal neutrophils obtained from mice treated as indicated in (D). Mean ± SEM (n ≥ 3). *P< 0.05, compared control or mice treated with compound C. ctr, Control; met or Met., metformin; W-pep, W-peptide; com. C, compound C.