Hyperglycemia-induced impaired neutrophil activity in the dynamic of burn wound healing in rats

BACKGROUND: Understanding mechanisms underlying hyperglycemia-induced dysfunctions in burn wound healing is an important biomedical issue. The aim was to assess how changes in systemic neutrophil functional activity in bone marrow (BM) and peripheral blood (PB) correlate with their recruitment to the burn wound site and the efficiency of wound healing in rats with altered glucose metabolism. METHODS: Diabetes mellitus (DM) was developed in Wistar male rats (176.8 +/- 8.3 g) by streptozotocin injection (50 mg/kg b.w.). Skin burn injury was induced in control and DM groups (N.=24) and healing dynamic was assessed (3, 7, 14, 21 days). The myeloperoxidase (MPO) activity in BM cells was assayed cytochemically. MPO content in regenerated tissue was determined by western blotting. Phagocytic index of PB neutrophils was assessed by latex test. RESULTS : DM group showed less healing rate (contraction to 35.8% from initial wound size compared with 25% in control on day 21). Hyperglycemia led to increased MPO activity in BM neutrophils (7th day: 18.97%, 14th: 20.15%, 21th: 14.34% vs. control). We detected hyperglycemiainduced decrease in MPO content in tissue regenerate at the early stage (3rd day: 66%, 7th: 44.4%) that reflects local neutrophil dysfunction. A tight correlation between wound contraction dynamics and Phagocytic Index of PB neutrophils was found. CONCLUSIONS: Burn injury in DM group was accompanied by an altered pattern of neutrophilic activity and recruitment at early stages: reduced ability to phagocytose, declined MPO content in skin regenerate and elevated MPO activity in BM that resulted in the inhibition of the wound closure rate.