Immunological aspects of the use of melatonin in experimental thermal trauma

The prevalence of thermal trauma, the high risk of infectious and non-infectious short- and long- term complications, and the limited effectiveness of the therapeutic approaches used are prerequisites for the search and pathogenetic justification of new therapies, among which the endogenous homeostasis regulator with pleiotropic properties melatonin attracts attention.The aim of the work is to investigate the immunological aspects of intraperitoneal use of melatonin (MT) in experimental thermal trauma (TT).The work was performed on 158 rats of the Wistar line, grade III TT and a relative area of 3.5% were simulated by skin immersion in water at 98-99 °C for 12 s. MT was administered intraperitoneally daily at a dose of 10 mg/kg for 5 days. The quantitative composition of blood cells was evaluated on a hematological analyzer. Plasma concentrations of IL-4, TNFa, IFNg, and CRP were determined on an automatic enzyme immunoassay using rat-specific test systems, and MT by capillary electrophoresis.With experimental TT, against the background of a progressive increase in the number of leukocytes in the blood from 5 to 20 days due to neutrophils, monocytes, basophils, the number of lymphocytes decreases. With TT, the concentration of CRP increases in serum on days 5 and 10. The content of TNFa, IL-4 increases on days 5, 10 and 20 in the absence of significant changes in the concentration of IFNg. The concentration of serum MT does not change significantly. Intraperitoneal use of MT in TT leads to a partial restoration of the number of lymphocytes in the blood on day 5. Evaluation of the cytokine profile in serum revealed a decrease in the concentration of TNFa on days 10 and 20, no significant changes in the concentration of IL-4 and IFNg were recorded, the concentration of CRP decreased on day 5. The concentration of serum MT increases by 5 days.With TT on the 5th, 10th, 20th day of the experiment, the number of neutrophils, monocytes, basophils in the blood increases, decreases – lymphocytes, the serum content of CRP, TNFa, IL-4 increases, the content of IFNg and melatonin does not change. Intraperitoneal use of MT in TT partially restores the number of lymphocytes in the blood, the concentration of CRP, TNFa. A decrease in serum concentrations of TNFa and CRP in TT under the conditions of MT use suggests a limitation of the acute phase response as a consequence of the antioxidant, anti-inflammatory effect of MT, which can accelerate healing and reduce the area of the lesion of TT.