Vitamin D3 availability and functional activity of peripheral blood phagocytes in experimental type 1 diabetes

Abstract

The study was devoted to identifying the relation between vitamin D 3 availability (assessed by the level of circulatory 25OHD 3), content of vitamin D3 25-hydroxylase isozymes CYP 27A1 and CYP 2R1 in hepatic tissue and functional activity of peripheral blood phagocytes in mice with experimental type 1 diabetes. It has been shown that diabetes is accom-panied by the development of vitamin D3-deficiency which is characterized by decreased 25OHD3 content in blood serum and determined by changes in tissue expression of the major isoforms of vitamin D3 25-hydroxylase. The level of hepatic CYP 27A1 was revealed to be markedly reduced with a concurrent significant augmentation of CY P2R1. Cholecalciferol administration resulted in normalization of tissue levels of both isoforms of vitamin D3 25-hydroxylase and blood serum 25OHD 3 content. Diabetes-associated vitamin D3 deficiency correlated with a decrease in phagocytic activity of granulocytes and monocytes, and their ability to produce antibacterial biooxidants such as reactive oxygen and nitrogen forms. Vitamin D3 efficacy to attenuate these abnormalities of immune function was established, indicating an important immunoregulatory role of cholecalciferol in the phagocytic mechanism of antigens elimination implemented by granulocytes and monocytes. © Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, 2014.