Focus on the anti-inflammatory effect of glucocorticosteroids in experimental acute lung injury

AIM: Assessment of the effect of various doses of dexamethasone as an inflammation modulator in experimental lipopolysaccharide-induced acute lung injury in rats.

MATERIALS AND METHODS: Acute lung injury in rats was modeled by intratracheal administration of cell wall lipopolysaccharide from the Salmonella enterica. White male rats were divided into groups: a group of intact animals (n = 10); the control group (n = 40), in which the animals were simulated acute lung injury without further treatment and removed from the experiment on day 3; three experimental groups (n = 40), in which, 3 hours after modeling acute lung injury, and then daily once a day for 3 days, dexamethasone solution was administered intraperitoneally in the following doses: in group 1 — 0.52 mg/kg (equivalent to 6.0 mg/day for a person), in group 2 — 1.71 mg/kg (20.0 mg/day for a person), in group 3 — 8.0 mg/kg (94.0 mg/day, pulse therapy for humans). On the 3^rd day, blood samples were taken from the caudal vena cava in surviving animals for clinical analysis and evaluation of the function of mitochondria of peripheral blood leukocytes. To determine the severity of local inflammatory reactions and pulmonary edema, bronchoalveolar lavage was performed with the study of an endopulmonary cytogram and an assessment of pathomorphological changes in the lung tissue.

RESULTS: indicate that dexamethasone reduces the amount of lung tissue damage and animal mortality, dose-dependently reduces the functions of mitochondria and the number of lymphocytes and monocytes in peripheral blood, as well as neutrophils, lymphocytes and macrophages in bronchoalveolar lavage samples.

CONCLUSION: The use of dexamethasone at a dose of 0.52 mg/kg (equivalent to 6.0 mg/day for humans) is accompanied by better survival, minimal effect on the viability and functional activity of inflammatory cells. Pulse therapy leads to a significant decrease in the number of immunocompetent cells in bronchoalveolar lavage, mitochondrial dysfunction in the form of a decrease in the ability of these cells to use the reserve power of mitochondrial respiration in response to the action of a stress factor. Excessive inhibition of immunocompetent cells can contribute to the activation of latent and opportunistic infections, which must be taken into account when choosing a dosing regimen for glucocorticosteroids.