[Production and internalization of extracellular vesicules in normal and under conditions of hyperglycemia and insulin resistance]

Extracellular vesicles (EVs) are spherical structures of cell membrane origin, ranging in the size from 40 nm to 5000 nm. They are involved in the horizontal transfer of many proteins and microRNAs. The mechanisms EV internalization include clathrin-dependent endocytosis, caveolin-dependent endocytosis, raft-mediated endocytosis, and macropinocytosis. Type 2 diabetes mellitus (T2DM) is a common group of metabolic disorders in adults; the incidence and prevalence increase in parallel with the obesity epidemic. Since adipose tissue plays a crucial role in the development of insulin resistance, EVs secreted by adipose tissue can be a kind of information transmitter in this process. EVs of adipocytic origin are predominantly absorbed by tissue macrophages, adipocytes themselves, hepatocytes, and skeletal muscles. This contributes to the M1 polarization of macrophages, a decrease in glucose uptake by hepatocytes and myocytes due to the transfer of functionally active microRNAs by these EVs, which affect carbohydrate and lipid metabolism. Patients with T2DM and impaired glucose tolerance have significantly higher levels of CD235a-positive (erythrocyte) EVs, as well as a tendency to increase CD68-positive (leukocyte) and CD62p-positive (platelets/endothelial cells) EVs. The levels of CD31+/CD146-positive BB (endothelial cells) were comparable between diabetic and euglycemic patients. EVs from diabetic patients were preferably internalized by monocytes (mainly classical and intermediate monocyte fractions and to a lesser extent by non-classical monocyte fractions) and B cells compared to euglycemic patients. Internalization of EVs from patients with T2DM by monocytes leads to decreased apoptosis, changes in differentiation, and suppression of reactions controlling oxidative stress in monocytes. Thus, insulin resistance increases secretion of EVs, which are preferentially internalized by monocytes and influence their function. EVs are considered as sources of promising clinical markers of insulin resistance, complications of diabetes mellitus (endothelial dysfunction, retinopathy, nephropathy, neuropathy), and markers of EVs can also be used to monitor the effectiveness of therapy for these complications.

Internalization of extracellular vesicles of cancer patients by peripheral blood mononuclear cells during polychemotherapy: connection with neurotoxicity

Extracellular vesicles (EVs), exhibiting their functional activity after internalization by recipient cells, are involved in the pathogenesis of drug-induced polyneuropathy (DIPN), a common complication of antitumor therapy. In this work, the internalization of EVs obtained from colorectal cancer patients undergoing polychemotherapy and its relationship with neurotoxicity were assessed using a model system of mononuclear leukocytes. Circulating EVs were isolated from 8 colorectal cancer patients who received antitumor therapy according to the FOLFOX or XELOX regimens before the start of chemotherapy (point 1) and after 3-4 courses (point 2). Mononuclear leukocytes of a healthy donor served as a cellular model system for EV internalization in vitro. EV internalization was assessed using fluorescence microscopy. It was shown that internalization of EVs obtained from colorectal cancer patients with high neurotoxicity was higher than in the group with low neurotoxicity. The ability of CD11b-positive (CD11b⁺) and CD11b-negative (CD11b⁻) mononuclear leukocytes of a healthy donor to internalize EVs obtained from patients before and after chemotherapy did not reveal significant differences. A direct relationship was found between the relative number of CD11b⁻ cells with internalized EVs and the integral index of neurotoxicity according to the NRS scale at the peak of its manifestation (point 2) (r=0.675, p.