Extracellular vesicles (EVs) are cell-derived membrane vesicles which play an important role in cell-to-cell communication and physiology. EVs deliver biological information from producing to recipient cells by transport of different cargo such as proteins, mRNAs, microRNAs, non-coding RNAs and lipids. Adipose tissue EVs could regulate metabolic and inflammatory interactions inside adipose tissue depots as well as distal tissues. Thus, adipose tissue EVs are assumed to be implicated in obesity-associated pathologies, notably in insulin resistance and type 2 diabetes mellitus (T2DM). In this study we for the first time characterize EVs secreted by visceral (VAT) and subcutaneous adipose tissue (SAT) of patients with obesity and T2DM with standard methods as well as analyze their morphology with cryo-electron microscopy. Cryo-electron microscopy allowed us to visualize heterogeneous population of EVs of various size and morphology including single EVs and EVs with internal membrane structures in samples from obese patients as well from the control group. Single vesicles prevailed (up to 85% for SAT, up to 75% for VAT) and higher proportion of EVs with internal membrane structures compared to SAT was typical for VAT. Decreased size of single and double SAT EVs compared to VAT EVs, large proportion of multilayered EVs and all EVs with internal membrane structures secreted by VAT distinguished obese patients with/without T2DM from the control group. These findings could support the idea of modified biogenesis of EVs during obesity and T2DM.

The growth of obesity and type 2 diabetes incidence has made bariatric surgery a widespread method of treatment. The effectiveness of bariatricoperations in the treatment of obesity and related metabolic diseases is thoroughly highlighted in medical literature. However, the resultsof surgery do not always correlate with type of operation. As before, the mechanisms have not been fully studied of how the bariatric surgeryinfluence on insulinresistance, entero-insulin axes, adipokines. Understanding such mechanisms will allow us to determine more precisely theindications relating to surgical treatment, and enhance the effectiveness of surgery in specific patient. The review is focusing on the influence ofvarious types of bariatric surgery on the level of adipokines and incretines that participate in regulation of appetite and of fat and carbohydratemetabolism. The article elaborates modern concepts related to the impact of bariatric operations on metabolic disorders in obesity.

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Obesity is considered now as a chronic relapsing lifelong disease, with a tendency to progression. According to the WHO, it present about 60% of the population of economically developed countries is overweight, 25-30% – is obesity. Russia is in fifth place in the world in the prevalence of obesity and overweight, being second only to the United States, Mexico, Hungary and Scotland. According to the Research Institute of Nutrition in the North-West region of the Russian Federation, 29.7% of women and 18.5% of men are overweight. Associated with obesity diseases include atherosclerosis, type 2 diabetes, hypertension, coronary heart disease, hormonal disorders, some cancers, etc. In proportion to the number of obese people increases and the incidence of pathological conditions associated with overweight. The vast majority of 95% of obese people die from causes directly related to overweight. The life expectancy of patients with overweight is reduced by 10-20 years, depending on the age of development and severity of obesity. The effectiveness of the conservative methods of correction associated with overweight in the arsenal of medicine today is low due to the complexity of the impact on their main cause – overweight. The article presents modern ideas about the mechanisms of action, hormonal and metabolic effects of the main types of bariatric operations. High long-term efficacy of surgical treatment of obesity-associated dis-orders of lipid and carbohydrate metabolism, arterial hypertension has been shown.