Features of beta cell differentiation during the development of type 2 diabetes mellitus

Abstract

Type 2 diabetes mellitus is characterized by a mild inflammatory reaction in the pancreas, which affects the structure and function of the pancreatic islets: the number of β-cells decreases and the number of α-cells increases. The work examined the features of β-cell differentiation in the development of experimental type 2 diabetes mellitus and while reducing the inflammatory process. Biochemical, histological methods, enzyme-linked immunosorbent assay, immunohistochemical methods were used using primary antibodies to insulin, glucagon, proliferation marker Ki-67 and secondary antibodies labeled with fluorescent dyes. Streptozotocin and nicotinamide were used to model type 2 diabetes mellitus, and the sodium salt of 5-amino-2,3-dihydrophthalazine-1,4-dione was used to reduce the inflammatory response. Previous studies have shown that it changes the macrophage phenotype from proinflammatory M1 to anti-inflammatory M2. In type 2 diabetes mellitus, against the background of a decrease in the number of macrophages with the CD163 marker and the concentration of the cytokine TGF-β1, which have an anti-inflammatory effect, in the pancreatic islets, a decrease in the number of β-cells and their functional activity was observed, while the content of α-cells synthesizing glucagon increased. After administration of the sodium salt of 5-amino-2,3-dihydrophthalazine-1,4-dione, the opposite picture was observed in the pancreatic islets: against the background of an increase in the number of CD163+ macrophages and the content of TGF-β1, the number of β cells increased and the number of α cells decreased-cells. The increase in the number of insulin-synthesizing cells was not accompanied by their mitotic activity. It is likely that a decrease in the number of CD163+ macrophages and the level of the antiinflammatory cytokine TGF-β1 in the islets are factors contributing to changes in the cell microenvironment and, as a consequence, the differentiation of β-cells into α-cells. On the contrary, an increase in the number of CD163+ macrophages and TGF-β1 against the background of administration of the sodium salt of 5-amino-2,3-dihydrophthalazine-1,4-dione presumably promotes reverse differentiation of α-cells into β-cells and restoration of insulin synthesis pancreas. Targeted effects on the microenvironment of cells in the pancreatic islet in type 2 diabetes mellitus may be a new approach to treating the disease.

Keywords

• type 2 diabetes mellitus
• α-cells
• β-cells
• β-cell differentiation
• macrophages
• cytokines