THE COMPLEX EFFECT OF VITAMIN D AND ALPHA TOCOPHEROL ACETATE ON THE LUNG MICROCIRCULATION IN THE EXPERIMENTAL INDUCTION OF SYSTEMIC SCLEROSIS

Abstract. The aim of the study was to investigate the effects of vitamin D3 (vitamin D) and alpha-tocopherol acetate (vitamin E) on the microcirculatory vessels of the lungs in an experimental model of systemic sclerosis (SSc). Methods. We divided the experimental animals into four separate groups: an intact group (IG) consisting of 15 animals, a control group (CG) of 20 animals, experimental group 1 (EG1) and experimental group 2 (EG2) consisting of of 25 animals each. Randomization of groups was carefully performed using the weight variance minimization method. To induce SSc in laboratory animals of EG1, subcutaneous injections of 0.5 ml of 5% sodium hypochlorite (NaClO) were administered 3 times a week for 6 weeks in a row. The CG of rats received an isotonic solution following the same scheme, while the IG was not subjected to any injections. In addition to NaClO, the EG2 received intramuscular injections of vit E (10 mg/100 g) and vit D (1000 IU/100 g) for three weeks during the second half of the experiment. After 8 weeks, the animals were euthanized, and lung tissue samples were obtained for histological and electron microscopic analysis. The histological preparations were examined using light microscopy and photographed using a Leica DME light microscope, a DCM 900 digital microscope camera, and a Nicon Coolpix P5100 camera. Meanwhile, the electron microscopy was performed to visualize the ultrastructural characteristics of the lung tissue by use of "PEM-125K" (Selmi, Ukraine) with subsequent photography at magnifications from 2000 to 20000 times. All animal procedures were carried out in strict compliance with bioethical principles. The Ethics Commission of the IFNMU granted approval for the study under document number 117/20 on November 19, 2020. Results. The histological analysis of the lung specimens of CG animals showed a normal morphological structure. In the EG1, the lungs exhibited abnormalities in the structure of the hemocapillaries, including narrowing of the vessel lumen due to thickening of the vascular wall, edema, and infiltration of polymorphonuclear cells. However, in the EG2, there was an improvement in the histological features, with a reduction in edematous processes and a decrease in the intensity of polymorphonuclear cell infiltration. The electron microscopic examination of the lung samples from EG1 animals revealed the presence of platelet adhesion and aggregation, as well as aggregates of erythrocytes within the hemocapillary lumen. Swelling of endothelial cells and narrowing of the hemocapillary lumen were also observed, along with uneven thickening of the basement membrane. In contrast, the combination of vitamins D and E in EG2 animals resulted in improved rheological properties of blood and ultrastructural characteristics of the hemomicrocirculatory elements. The lumen of the hemocapillaries contained single erythrocytes and inactive platelets. The endothelial cells’ membraines showed minimal alterations, with clear contours and no micropinocytotic vesicles or cytoplasmic growths. The nuclei of the endothelial cells had a fine-grained matrix with evenly distributed chromatin granules. Conclusions. This study proves that the combined use of vitamins D and E has a positive effect on the state of the microcirculatory vessels in the lungs of experimentally induced systemic sclerosis.