Insulin attenuates the cytokine response in a burn wound infection model

A massive burn is one of the most serious injuries resulting in major imbalances of the immune system. The aftermath of a burn is frequently complicated by infections and septic events that additionally increase mortality and morbidity. The aim of the present study was to investigate if insulin attenuates the cytokine response of burned mice challenged with Pseudomonas. Male mice (C57/BL/6) received a full thickness burn of 35% of their total body surface area. Mice received 5 IU/kg insulin i.p. or an equal volume of saline for 5 days after burn. Mice were challenged with 5x10 colony forming units Pseudomonas aeruginosa intraperitoneally. Serum was harvested 6 h after the bacterial challenge, and 18 serum cytokines were measured using the Bio-Plex suspension array system (Bio-Rad, Hercules, Calif). All 18 cytokines were elevated after the Pseudomonas challenge. However, mice treated with insulin showed significantly lower proinflammatory cytokine concentrations of interleukin 5, interleukin 6, and keratinocyte-derived chemokine after the Pseudomonas infection when compared with placebo-treated mice (P<0.05). In contrast, serum concentrations of G-CSF were significantly higher in insulin-treated animals when compared with placebo (P<0.05). We conclude, that insulin treatment selectively modulates specific cytokines in a burn wound infection model.