THE FUNCTIONAL ACTIVITY OF INNATE IMMUNITY CELLS IN BACTERIAL INFECTION ON BACKGROUND OF THERMAL STRESS

Abstract

Maintenance of thermo homeostasis under the coordinating influence of the hypothalamus is ensured by integrative interaction of various systems organisme, including the immune system. Temperature stress in infectious diseases activates the reaction of heat shock, the biochemical consequence of which is the initiation of the organism’s defense against the pathogen. Cells of innate immunity (neutrophils and macrophages) are the first line of protection against pathogenic agents and play a primary role in the development of bacterial infections. Of particular interest is the study of the duration of the effect of hyperthermia to achieve a balance between the bioenergetic costs of these cells, as well as the study of the course of the pathological process in an organism previously exposed to hige temperature. The functional status of neutrophils and macrophages, including phagocytosis, the activity of enzymes of the oxygen-dependent system: lactate dehydrogenase, cytochrome oxidase, myeloperoxidase, cellular stimulation (intracellular AMPase content) and the content of nitrogen oxide metabolites have been studied in the model of animals exposed to low and high temperatures. It has been established that under hyperthermia conditions, the change in the functional activity of cells by enzyme level is more pronounced than when exposed to animals with low temperature, especially 4 h exposure. In animals pre-exposed to heat stress, manifestations of pseudotuberculosis infection were more severe with an increase in mortality rates by 2.6 times, compared to animals infected by bacteria. These animals had a high stimulation of effector cells of inflammation in the initial periods (at 7 days) their metabolism was enhanced, which was expressed of the activity of enzymes of the oxygen-dependent system, as well as in high nitroxide-producing activity. In target organs (lung, liver, spleen) of experienced animals the severe disturbance of blood circulation in combination with significant destructive changes typical for generalized infection were showed. At dead animals on the background of marked hemorrhagic component pathological process and weak cell inflammatory response observed depletion of the immune system (delimphatization), indicating a decrease in defense reactions and the development of immunodeficiency. Thus, under conditions of heat stress (+30°С), the intensity of the reaction of innate immunity cells in terms of enzyme’s functional activity was higher than when exposed to animals of low temperature (+4°C). Under these temperature conditions, a high level of cell priming was determined, which reduced their killing potential. These data indicate the adequacy of the model used to reproduce induced secondary immunodeficiency in a congenital defense system. Moreover, in the pathogenesis of pseudotuberculosis infection against the background of prolonged action high temperature, the effects of phagocytes oxidative stress in the structural changes of immunocompetent organs were detected.