M. A. Vasilenko

Nitric oxide and mitochondria in metabolic syndrome

Metabolic syndrome (MS) is a cluster of metabolic disorders that collectively increase the risk of cardiovascular disease. Nitric oxide (NO) plays a crucial role in the pathogeneses of MS components and is involved in different mitochondrial signaling pathways that control respiration and apoptosis. The present review summarizes the recent information regarding the interrelations of mitochondria and NO in MS. Changes in the activities of different NO synthase isoforms lead to the formation of metabolic disorders and therefore are highlighted here. Reduced endothelial NOS activity and NO bioavailability, as the main factors underlying the endothelial dysfunction that occurs in MS, are discussed in this review in relation to mitochondrial dysfunction. We also focus on potential therapeutic strategies involving NO signaling pathways that can be used to treat patients with metabolic disorders associated with mitochondrial dysfunction. The article may help researchers develop new approaches for the diagnosis, prevention and treatment of MS.

Pathogenesis of insulin resistance in metabolic obesity

This review considers molecular mechanisms of insulin resistance developed under conditions of metabolic inflammation; special attention is paid to analysis of the results of experimental and clinical studies work aimed at identifying molecular targets for the development of new methods for prevention and treatment of insulin resistance.

The role of production of adipsin and leptin in the development of insulin resistance in patients with abdominal obesity

We investigated the tissue-specific features of the production of adipokines (leptin and adipsin) by adipose tissue in obese patients depending on the degree of obesity and the state of carbohydrate metabolism. An increase in the content of adipsin and leptin in the blood plasma was found. In patients with varying degrees of obesity with and without type 2 diabetes mellitus (DM 2), we determined the level of tissue-specific expression of LEP and CFD genes encoding leptin and adipsin, respectively. The contribution of different adipose tissue depots to the blood plasma level of adipsin and leptin in obese patients with and without DM 2 was established. The disturbance of reciprocal relationships between adipsin and leptin in obesity is associated with the development of insulin resistance.

Evaluating the number of mitochondrial DNA copies in leukocytes and adipocytes from metabolic syndrome patients: Pilot study

Metabolic syndrome is a complex of metabolic, hormonal, and clinical disorders. Defects in mitochondrial functions play an important role in the metabolic syndrome pathogenesis. Here, variations in the number of mitochondrial DNA (mtDNA) copies were evaluated in different fat-tissue and peripheral-blood-leukocyte samples from metabolic syndrome patients ranked by body mass indices. The number of mtDNA copies showed a tendency to decrease with increase body mass index.

The pathogenetic importance of C774T single nucleotide polymorphism of the endothelial nitric oxide synthase gene in the development of metabolic syndrome

The relationship between nitric oxide production and metabolic disorders and the role of endothelial nitric oxide synthase (eNOS or NOS3) in metabolic syndrome (MS) remain poorly understood and need deeper investigation. In this context the role of the NOS3 gene in pathogenesis of MS is of special interest. The aim of the study was to investigate association of NOS3 single nucleotide polymorphism C774T with risk of MS in the Slavic population of the Kaliningrad region and the relationship of this polymorphic variant with some parameters of endothelial dysfunction. The study included 128 patients (48 men and 80 women aged from 36 to 52 years) with MS. The control group consisted of 126 healthy volunteers (60 men and 66 women aged from 30 to 40 years). Genotyping was performed by real-time PCR. Serum nitrite levels were determined spectrophotometrically by the Griess method. Serum levels of endothelin-1 and eNOS were evaluated by ELISA. The study has shown association of T allele (OR = 2.06; p = 0.0004; CI: 1.38–3.08) and CT genotype (OR = 1.97; p = 0.014; CI: 1.14–3.40 ) C774T polymorphism of the NOS3 gene with risk of MS in the Slavic population of the Kaliningrad region. Allele C (OR = 0.48; p = 0.0004; CI: 0.32–0.72) and homozygous CC genotype (OR = 0.41; p = 0.001; CI: 0.24–0.69) C774T polymorphism of the NOS3 gene were associated with reduced risk of the development of MS. Significant differences in serum levels of eNOS and endothelin-1 depended on the CT and TT genotypes of C774T polymorphism of the NOS3 gene in MS.

Additional evidence of the link between mtDNA copy number and the body mass index

Mitochondria are the central players in cellular energy production. Mitochondrial DNA (mtDNA) encodes core subunits of oxidative phosphorylation complex (Anderson et al. 1981) and thus it is expected that the total number of mtDNA copies fits the requirements of each cell type as a result of a regulatory crosstalk between nuclear and mitochondrial genomes (Clay Montier et al. 2009). Deviations from the optimal number of mtDNA copies are expected to be deleterious and might cause some diseases and aging. The reasons of potential deviations in mtDNA copies might be genetic (R€ otig and Poulton 2009) or environmental, such as hormonal imbalance in non-hereditary diseases (Prikoszovich et al. 2011). There is increasing evidence of mitochondrial involvement in the pathogenesis of obesity and subsequent metabolic syndrome (MS). In particular, the study has shown that mitochondrial dysfunctions lead to oxidative stress, which initiates the development of atherosclerosis, cardiovascular disease, and insulin resistance, the hallmarks of obesity (Devarshi et al. 2017; Ong et al. 2017). It is widely accepted that changes in the level of mtDNA in peripheral blood leukocytes can also lead to oxidative stress and can correlate with the development of MS (Huang et al. 2016). Our previous data suggested a decreased peripheral blood mononuclear cell’s mtDNA copy number in individuals with high body mass index (BMI) (Mozhe K % et al. 2014). To test these initial observations in this study, we used the droplet digital PCR (ddPCR) approach to estimate the absolute mtDNA copy numbers in several tissues (peripheral blood mononuclear cell, liver tissue, several different locations of adipose tissues) of MS individuals with various degrees of obesity. We found out that the BMI correlates positively with the number of mtDNA copies in subcutaneous adipose tissues (SATs) but negatively with mtDNA copies in peripheral blood mononuclear cells and liver.

The Role of Mitochondrial DNA ORIB Polymorphism in Metabolic Syndrome

The development of the metabolic syndrome (MS) involves many genes. Certain evidence exists in the literature on the association of polymorphism in the mitochondrial DNA (mtDNA) oriB site, also known as the polycytosine pathway, with the development of insulin resistance, type 2 diabetes mellitus (T2DM) and other metabolic disorders in various ethnic populations. It is suggested that certain polymorphisms at this site are associated with mtDNA copy number in the cell. In this study, using capillary sequencing, we have identified various allelic variants of the mtDNA oriB site in patients with MS (n = 106) and conditionally healthy donors (n = 71). The mtDNA copy number in blood leukocytes was determined by the droplet digital polymerase chain reaction (ddPCR). It has been shown that the variant of the continuous polycytosine tract is significantly more frequent in MS patients with T2DM (p < 0.01). In general, the mtDNA copy number of blood leukocytes was lower in MS patients than in controls. We did not find any correlations between the oriB site variability and the mtDNA copy number.

Changes of Chemerin Production in Obese Patients with Different States of Carbohydrate Metabolism

Chemerin is an adipose tissue mediator involved in the regulation of many processes, including lipogenesis, inflammatory responses, etc. The role of chemerin in the development of insulin resistance still needs better understanding. The aim of the study was to investigate chemerin production in obese patients with different states of carbohydrate metabolism. The study included 155 patients with diagnosed obesity and 34 patients with overweight. The control group 1 consisted of 43 conditionally healthy donors without obesity. For comparison of the research data on evaluation of tissue-specific mRNA expression of the genes IL-6, TNF-α, RARRES2, (encoding IL-6, TNF-α, and chemerin, respectively) control group 2 consisting of 30 non-obese was also included into this study. The relative level of mRNA expression of the genes IL-6, TNF-α and RARRES2 (encoding IL-6, TNF-α and chemerin, respectively) was carried out using real time PCR. Concentrations of IL-6, TNF-α, and chemerin were measured in serum/plasma using an enzymelinked immunosorbent assay (ELISA). Significant differences were found in the plasma level of chemerin and tissue-specific patterns of RARRES2 gene expression in obese patients; these changes depended on the degree of obesity and the state of carbohydrate metabolism. Opposite associations between RARRES2 gene expression and expression TNF-α and IL-6 genes have been recognized in adipose tissues of different localization: in obese patients (BMI ≤ 40 kg/m2) without type 2 diabetes mellitus (DM2) they were negative, while in obese patients with DM2 diabetes they were positive. The recognized correlations between the plasma content of chemerin and the expression level of its gene in biopsies with various parameters of carbohydrate and lipid metabolism, and proinflammatory molecules indicate chemerin involvement in metabolic and immune processes in obesity.

Association of Glu298Asp Polymorphism of Endothelial NO Synthase Gene with Metabolic Syndrome Development: a Pilot Study

We studied association of single nucleotide polymorphism Glu298Asp (rs1799983) of the NOS3 gene with the risk of metabolic syndrome in the Slavic population. Blood samples were obtained from 128 patients with metabolic syndrome and 100 healthy individuals. Polymorphism Glu298Asp of the NOS3 gene was genotyped by allele-specific PCR. Allele Asp (OR=1.95, 95%CI 1.29-2.95, p=0.007) and genotype Asp/Asp (OR=2.56, 95%CI 0.98-6.72, p=0.04) were associated with the risk of metabolic syndrome in Slavic population. Patients with metabolic syndrome carrying genotype Asp/Asp had higher serum endothelin-1 level in comparison with Glu/Asp and Glu/Glu carriers.

The association of the mitochondrial DNA oriB variants with metabolic syndrome

Different genes are involved in the development of pathology and formation the metabolic syndrome (MS) phenotype. In the literature, there is a data connection to the site oriB polymorphisms of mitochondrial DNA (mtDNA), known as 16184-16193 polycytosine tract, with insulin resistance, type 2 diabetes (T2DM) and other metabolic abnormalities in different ethnic populations. It is supposed that for certain polymorphisms at this site decreases mtDNA copy number in the cells. In this study, we have identified different allelic variants of the mtDNA oriB site in MS patients (n=106) and healthy individuals (n=71) using capillary sequencing, and determined the amount of mtDNA copy blood leukocytes by droplet digital polymerase chain reaction (ddPCR). The continuous polycytosine tract was significantly more common in MS patients, and such a link was particularly strong in MS patients with type 2 diabetes (p<0.01). No significant correlation has been found between mtDNA copy number and the oriB site variants, but in general there is a tendency to decreased mtDNA copy number in MS patients.