[Apolipoprotein A-I stimulates secretion of insulin and matrix metalloproteinases by islets of Langerhans].

The development of type 2 diabetes mellitus (DM2) is accompanied by disturbances in lipid metabolism. These include the increase in serum levels of atherogenic fractions of very low-density (VLDL) and low-density lipoproteins (LDL), total cholesterol, triglycerides and apo B. In contrast, the level of antiatherogenic high density lipoproteins (HDL) and the content of apolipoprotein A-I (apoA-I) decreased. To study the effect of the observed metabolic changes on insulin secretion in vitro, we used the islets of Langerhans isolated from the rat pancreas. It has been found that incubation of the islets in the presence of serum of the obese patients and patients with decompensated DM2 leads to a decrease in insulin secretion by 2.4 and 5.0 times, respectively. On the contrary, the addition of HDL to the incubation medium increased the insulin secretion by 3.4 times. A similar effect was observed in the presence of apoA-I, the main protein component of HDL. In the presence of apoA-I, the extracellular activity of matrix metalloproteinases (MMPs) demonstrated a 10-fold increase. The addition of LDL and VLDL to the islets did not change the secretion of insulin and activity of MMP. Our results testify to the important role of HDL and apoA-I in regulation of the insulin secretion by b-cells and the activity of MMPs in the islets of Langerhans.