Figure 5
From: Activation of AMPK Enhances Neutrophil Chemotaxis and Bacterial Killing
Metformin increases bacteria uptake and killing in vitro and in vivo. (A, B). Neutrophils (106 cells/mL) were pretreated with or without metformin (500 µmol/L) for 2.5 h and then incubated with fluorescently tagged E. coli(107/mL) (A) or S. aureus (107/mL) (B) for additional 20 min. Neutrophil-dependent uptake of bacteria was determined using flow cytometry. Means ± SEM (n = 3), *P < 0.05 or **P < 0.01. (C, D) Neutrophils (2 × 106 cells/mL) were pretreated with metformin (0 or 500 µmol/L) for 2.5 h, AICAR (0 or 250 µmol/L) for 2 h, LPS (1 µg/mL), compound C (10 µmol/L) or rapamycin (10 nmol/L) for 60 min. Next, neutrophils were incubated with E. coli (2 × 107/mL) for 90 min. Images (C) show agar plates with colonies formed by viable E. coli that were obtained after incubating bacteria with neutrophils. Panel (D) shows the number of viable bacteria recovered from killing assay. Means ± SEM (n = 4), *P < 0.05 compared with control. (E, F, G) Mice were subjected to the administration of metformin (125 mg/kg; IP) for 12 h, compound C (3 mg/kg; IP), or vehicle (0.9% saline) for 2 h followed by IP injection of E. coli (2 × 108) for an additional 6 h. (E) Representative images showed the number of E. coli colonies formed from viable bacteria that were recovered from peritoneal lavages. (F, G) Average of viable bacteria (F) and neutrophils (G) obtained from peritoneal lavages (mean ± SEM, n ≥ 5). *P < 0.05, **P < 0.01. RFU, relative fluorescence unit; ctr, control; met, metformin; CFU, colony-forming unit; com. C, compound C.