Reactive shifts in neutrophil cells of the bone marrow and peripheral blood after local acute frostbite

Abstract

It is known that neutrophils during the inflammatory process play a role both in regulating the behavior of cells involved in inflammation and in the destruction and removal of factors that cause inflammation and damaged tissue. However, there is no quantitative information on the participation of neutrophils in the destruction of the extracellular matrix of the dermis.

Aim. To study the mechanism of reactive shift of neutrophil cells of the red bone marrow and peripheral blood during remodeling of the extracellular matrix of the dermis on a model of acute frostbite.

Materials and methods. The 100 practically healthy rats with a body weight of 180–200 g at the age of 4–5 months were selected as objects of experimental research. Laboratory animals, in which acute frostbite was simulated, formed five groups, each of which included 20 individuals. The comparison group included 20 intact mongrel rats. All rats were kept in a special room free of pathogens and maintained at a constant temperature (23–25℃), humidity (40–50%) and a 12-hour light/dark cycle. Contact frostbite was reproduced with a metal weight cooled to the temperature of liquid nitrogen. All stages of the study were performed using closed-circuit chloroform anesthesia. The animals were removed from the experiment on the 3^rd, 7^th, 14^th and 21^st days, followed by histological examination of damaged skin, peripheral blood and red bone marrow.

Results. On the 3^rd day after acute local frostbite, a leukocyte shaft is formed in the dermis, consisting mainly of neutrophils, against the background of a decrease in the content of collagen in the dermis and the thickness of its fibers. The processes of degradation of the extracellular matrix of the dermis negatively correlate with an increase in the blood content of neutrophils with segments 3 and 4 in the nucleus. An increase in the collagen content of the dermis and the thickness of its fibers on the 7^th day and by the end of the experiment was accompanied by a decrease in the level of correlations.

Conclusion. Based on the data obtained, it can be assumed that neutrophils, especially those containing segments 3 and 4 in the nucleus, are involved only in the degradation of the extracellular matrix of the dermis, but are not involved in the direct synthesis of collagen fibers.