The Influence of Adiponectin on Transport of Low-Density Lipoproteins through Human Endothelial Cell Monolayer In Vitro.

The influence of adiponectin, a protein secreted by adipocytes, on the activation of transendothelial LDL transport, the initial event of atherogenesis, was studied. The addition of adiponectin to the cultured endothelial hybridoma EA.hy926 cells did not affect both basal and TNF-stimulated transendothelial transport of LDL. In addition, adiponectin affects neither expression levels of CAV1, SCARB1, and ACVRL1 genes encoding proteins involved in transendothelial LDL transport, nor the MMP secretion by the EA.hy926cells. At the same time, adiponectin suppressed the TNF-stimulated IL-8 production and expression of the adhesion molecule gene ICAM1 in these cells. Thus, adiponectin reduces proinflammatory activation of EA.hy926 cells, which is not accompanied by changes in the transendothelial LDL transport. We speculate that anti-inflammatory action of adiponectin is the base for the influence of this adipokine on atherogenesis.

[Adiponectin in normal and atherosclerotic intima of human aorta]. / Adiponektin v normal'noi i ateroskleroticheski izmenennoi intime aorty cheloveka.

BACKGROUND: Adiponectin (AN) is a protein synthesized by adipocytes that has regulatory effects on lipid and lipoprotein metabolism, increases tissue sensitivity to insulin, and modulates endothelial functions and inflammatory response. However, its involvement in the processes of atherogenesis remains poorly understood. OBJECTIVE: To determine the localization and sources of AN in atherosclerotic and normal human aortic intima. MATERIAL AND METHODS: Immunohistochemical study was performed on sections of atherosclerotic and normal human aorta obtained during autopsy. Reverse transcription real-time PCR was performed using biopsies of para-aortic and abdominal adipose tissue, intima-media of the thoracic aorta, atherosclerotic plaques of the human carotid and femoral arteries, as well as on endothelial cells isolated from the human thoracic aorta. Transendothelial transport of AN was evaluated in a two-chamber model using a monolayer of human endothelial cell hybridoma EA.Hy926. RESULTS: It has been established that AN is present in atherosclerotic but not in normal human aortic intima. At the same time, AN ADIPOQ mRNA was not detected either in the intima media of the human aorta, nor in isolated endothelial cells of the aorta, nor in cells of atherosclerotic plaques of the carotid and femoral arteries. AN slowly penetrated the endothelial monolayer in vitro, but this transport was significantly enhanced by the action of tumor necrosis factor-alpha (TNFa). CONCLUSION: Obtained data indicate that AN is present in atherosclerotic but not in normal aortic intima. We assume that AN is not synthesized by the cells of normal and atherosclerotic arterial walls, but permeates from the plasma. Transendothelial transport of AN, like many other plasma proteins, is activated during the development of atherosclerotic lesions, apparently under the action of pro-inflammatory cytokines, in particular, TNFα.

[The changes of copper metabolism in rats fed with low- or high-calorie ration].

Copper is an essential micronutrient, because it is a catalytic and structural cofactor of enzymes that control the basic processes in all cells, and moreover it is a participant in signaling pathways. The toxic properties of copper ions, due to their chemical nature, are manifested when the cellular and/or organism systems for copper homeostasis are disturbed. Aim of the work was to study the relationships between the diet caloric and the copper status in the blood serum, the copper metabolism in the liver and white adipose tissue (WAT) of rats. MATERIAL AND METHODS: The work was performed on three groups (each n=5) of white outbred rats (average body weight 220±15 g), kept for 75 days on a standard, low-calorie (LCR) or high-calorie (high-fat) (HCR) rations. mRNA concentration was measured by qRT-PCR technology. The сeruloplasmin (CP) content was determined by the method of immune electrophoresis, immune blotting and by oxidase activity. The copper concentration was measured by atomic absorption spectrometry. RESULTS AND DISCUSSION: It has been shown that serum level of triglycerides increased in rats fed LCR. The main indicators of copper status (concentration of atomic copper, the level of holo-CP, and the content of immunoreactive CP) decreased in rats fed HCR. In the liver, none of the diets affected Cp gene expression level. In the cells of the subcutaneous fatty tissue, the concentration of both splice-forms of CP-mRNA significantly increased in rats fed LCR. In visceral adipose tissue the concentration of Cp-mRNA encoding the secretory CP did not change in LCR-rats, but the level of mRNA, encoding CP anchored to plasma membrane, dropped to almost zero as compared to the control group. There was no significant change in the level of both splice-forms of CP-mRNA in HCR-rats. The features of copper metabolism in the cells of the liver and WAT, due to the caloric content of ration, have been discussed. CONCLUSIONS: In rats' liver, the link between copper metabolism and calorie intake is manifested in changes in the expression of the CP gene at the translation level, and in white adipose tissue - at the level of transcription and post-transcriptional maturation of the pre-mRNA of this gene.

[Antibodies against modified low-density lipoproteins and their complexes in blood of patients with various manifestations of atherosclerosis]. / Soderzhanie antitel k modifitsirovannym lipoproteinam nizkoi plotnosti i ikh kompleksov v krovi patsientov s razlichnymi proiavleniiami ateroskleroza.

The study included 79 patients with coronary artery disease, 25 individuals with preclinical atherosclerosis and 59 healthy controls. Key lipid parameters were examined in all the participants. Levels of antibodies (Abs) against (IgG and IgM) LDL modified by malondialdehyde (MDA), acetic anhydride and hypochlorite, were determined by the enzyme-linked immunosorbent assay (ELISA). Abs specificity was tested by competitive ELISA. Circulating immune complexes (CIC) were isolated by precipitation in polyethylene glycol. Abs to hypochlorite-modified low density lipoprotein (hypochlorite-LDL) were detected in the serum samples. These Abs did not demonstrate cross-reactivity with MDA-modified LDL (MDA-LDL) and acetylated LDL (acetyl-LDL). Patients with coronary artery disease had increased levels of CIC (p<0.0001) and decreased levels of Abs (IgM) to hypochlorite-LDL, compared with healthy controls and patients with preclinical atherosclerosis (p=0.006). A correlation between the levels of Abs (IgG) to the hypochlorite-LDL and Abs to MDA- and acetyl-LDL was found. There was a correlation between the content of the Abs (IgM) to MDA- and acetyl-LDL and the concentration of CIC-cholesterol. Lipid parameters did not correlate with Abs levels.

[ABCG1 transporter gene expression in peripheral blood mononuclear cells of patients with atherosclerosis].

Accumulation of cholesterol in arterial wall macrophages is a main hallmark of atherosclerosis. The ABCG1 transporter mediates cholesterol efflux to high density lipoproteins (HDL) and plays an important role in macrophage foam cell formation. The goal of our study was to investigate the potential role of ABCG1 in atherosclerosis development in humans. ABCG1 gene expression has been examined in leukocytes, monocytes and monocyte-derived macrophages of patients with atherosclerosis and in the control group. Real time PCR and Western blotting were used to determine ABCG1 mRNA and ABCG1 protein levels. Monocyte ABCG1 mRNA level was inversely correlated with the rate of artery occlusion (r = -0.45, P = 0.016). Patients with 100% artery occlusions had decreased monocyte ABCG1 mRNA levels compared to patients who had smaller plaques and controls (P < 0.05). ABCG1 mRNA (P < 0.001) and ABCG1 protein (P < 0.05) levels in macrophages of patients with coronary artery stenosis were significantly reduced compared to the control group. No significant correlation between the ABCG1 gene expression in mononuclear cells and HDL cholesterol concentration has been found. Our study suggests that decrease in the ABCG1 gene expression in macrophages is associated with atherosclerosis.

[[Length polymorphism of minisatellite repeat B2-VNTR of the bradykinin B2 receptor gene in healthy Russians and in patients with coronary heart disease].

Bradykinin B2 receptor is involved in many processes, including the regulation of blood pressure and smooth muscle contraction, vasodilation, inflammation, edema, cell proliferation, pain. It is suggested that this receptor may be one of the factors that have cardioprotective and infarct-limiting effects. It is assumed that certain genetic variants in both coding and non-coding regions ofBDKRB2 gene may influence its expression. In the 3'-untranslated region of BDKRB2 exon 3 the minisatellite repeat B2-VNTR is located. B2-VNTR has previously been shown to affect the BDKRB2 mRNA stability. Therefore, it is important to perform the molecular genetic analysis of this minisatellite in patients with different forms of coronary heart disease in order to reveal possible associations between specific B2-VNTR alleles and certain clinical forms of coronary heart disease. In the present study, a comparative analysis of the allele and genotype frequencies of B2-VNTR was carried out in groups of healthy individuals and patients with two clinical forms of coronary heart disease (angina pectoris and myocardial infarction), ethnically Russian. The results of the B2-VNTR length polymorphism analysis indicate that this tandem repeat may be attributed to a class of low polymorphic and non-hypervariable minisatellite. In all analyzed groups we revealed three B2-VNTR alleles, consisting of 43, 38 and 33 repeat units. Alleles of 43 and 33 repeats were major in all investigated groups. No statistically significant differences were found in the B2-VNTR allele and genotype frequencies between men and women in control group, and also between healthy men and men with angina pectoris and myocardial infarction. Thus, B2-VNTR length polymorphism was not associated with these clinical forms of coronary heart disease in Russian men. However, we do not exclude the possibility of association between the B2-VNTR short alleles (38 and 33 repeats) and cardioprotective effects of bradykinin B2 receptor in women with coronary heart disease. This hypothesis requires further investigation.

[Molecular forms of adiponectin: comparative evaluation of their correlations with parameters of carbohydrate and lipid metabolism].

Interrelationship between total, multimer (MM) and oligomer (OM) adiponectin blood concentrations with some metabolic parameters has been investigated in 49 men and 49 women (mean age of 57.3 +/- 10.1 years). We have found negative correlations between total blood adiponectin and its MM form content with body mass index, waist circumference, the insulin resistance index HOMA, with blood concentrations of insulin, glucose, free fatty acids, triglycerides and also positive correlations with high density lipoprotein cholesterol content. There was a poor correlation between OM adiponectin concentration with any parameter studied. According to the regression analysis, concentration of total adiponectin but not its MM form was an independent determinant of the HOMA index in women and free fatty acid concentration in men. In the group of men with the low level of adiponectin its MM form but not total adiponectin reversely correlated with the HOMA index and was its independent determinant. Thus, correlation between blood adiponectin concentration and metabolic parameters is associated with its MM rather than OM form. Study of the role of adiponectin in development of metabolic disorders may be limited to determination of total blood adiponectin concentration except a group of male patients characterized by a low level of this adipokine. In these patients concentrations of the MM form should be determined.

[ABCA1 gene expression in peripheral blood lymphocytes and macrophages in patients with atherosclerosis].

ABCA1 transporter is known to play important role in the cholesterol transport from peripheral tissues. However its contribution in atherosclerosis development remains not completely understood. Using Real Time PCR, a significant reduction of ABCA1 mRNA level in leukocytes of patients with atherosclerosis was determined when compared with controls. Mean ABCA1 expression levels in leukocytes for the group of patients and for the control group are 0.57 +/- 0.28 and 0.93 +/- 0.14 (p = 0.02). At the same time we detected a significant increase of ABCA1 mRNA level in macrophages of patients when compared with controls. Mean ABCA1 expression levels in macrophages for the group of patients and for the control group are 1.32 +/- 0.10 and 0.90 +/- 0.14 (p = 0.014). In summary, we suggest that expression level of ABCA1 gene may contribute to the development of atherosclerosis.

[Determination of human plasma concentration of asymmetric dimethylarginine by high performance liquid chromatography using an electrochemical detector].

Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NO synthetase. Elevated ADMA levels are accompanied by impaired endothelium-dependent vasodilation in the brachial artery and increased intima-media thickness in the elastic arteries. The purpose of the study was to develop a procedure for qualitative and quantitative determination of the plasma content of free ADMA and symmetric dimethylarginine by reverse-phase high performance liquid chromatography in an isocratic elution mode, by applying an electrochemical detector. Ortho-phthalic aldehyde with the sulfur-containing component sodium sulfite was used as a derivation reagent. The mobile phase is a system that consists of acetonitrile, sodium hydrophosphate, and sodium dihydrophosphate. The retention time for the detectable substance on the column was 21.7 min. The total time of the analysis was 31 min. In patients with the clinical manifestations of atherosclerosis and in healthy individuals, the plasma ADMA concentration measured by the devised method was 0.69-0.30 and 0.13-0.04 microM, respectively.

[Role of adipokines and nonesterified fatty acids in the development of insulin resistance].

The purpose of the study was to reveal a possible role of adipokines, biologically active adipose tissue proteins (leptin and adiponectin) and nonesterified fatty acids in generating insulin resistance (IR). One hundred and fifty-seven patients (90 females and 67 males) aged 57.5±9.2 years were enrolled in the study. According to the HOMA index for IR, the patients were divided into 3 equal groups. The examinees with a high HOMA index were found to have elevated levels of fatty acids, leptin and decreased concentrations of adiponectin. At the same time according to the linear regression analysis, all these indices are its independent determinants. However, analysis of the data in the groups of patients with different body weight revealed that the increased concentrations of fatty acids and leptin may play a role in the development of IR in subjects with obesity while the higher level of fatty acids and lower adiponectin may be involved in patients without noticeable obesity. Thus, it may be assumed that leptin, adiponectin and nonesterified fatty acids may affect the development of IR; however, their contribution depends on the degree of adiposity.

[Adiponectin: lowering in metabolic syndrome and independent relation to hypertriglyceridemia].

Aim of the study was to elucidate possible role of adiponectin in development of clinico-metabolic derangements in metabolic syndrome (MS). We examined 35 men and 45 women (mean age 58.0+/-8.8 years). Adiponectin level was significantly lower (p<0.01) in patients with MS (5.8+/-4.6) compared with subjects without MS (9.2+/-5.3 mkg/ml). Body mass index (BMI), waist circumference (WC), index of insulin resistance , levels of glucose, insulin, free fatty acids (FFA), triglycerides (TG) were lower in 3rd tertile of distribution of adiponectin blood content compared with 1st tertile. Significant negative correlations were found between adiponectin content and BMI (r=-0.36), WC (r=-0.34), index (r=-0.31), level of diastolic arterial pressure (r=-0.34), concentrations of glucose (r=-0.24), insulin (r=-0.26), FFA (r=-0.24), TG (r=-0.45), uric acid (r=-0.29). Correlation between adiponectin and level of high density lipoprotein cholesterol was positive (I=0.26). However after adjustment for MI, sex, and age adiponectin content correlated significantly only with concentration of TG (r=-0.27) and diastolic arterial pressure (r=-0.26). Regression analysis revealed independent from factors presented above role of adiponectin in determination of blood level of TG (beta=-0.30, p=0.02).

[Familial hypercholesterolemia in St. Petersburg: diversity of mutations argues against a strong founder effect].

Examination of low-density lipoprotein (LDL) receptor, its promoter, and major exon-intron boundaries from a sample of patients with familial hypercholesterolemia (FH) from 74 probands of St. Petersburg revealed 34 mutations and 8 widely spread polymorphisms at this locus. Only four mutations were considered silent, while the other 30 are likely associated with familial hypercholesterolemia (FH). Mutations in the LDL receptor gene, inducing the disease, were identified in 41 (55%) out of 74 families with FH. Mutation R3500Q in apolipoprotein B (APOB) gene was not detected in all probands. Therefore in the families lacking mutations hypercholesterolemia was induced by mutations in the introns of the LDL receptor gene or by other genetic factors. Nineteen mutations causing disease progression were described in St. Petersburg for the first time, while 18 of them are specific for Russia. Among Ashkenazi Jews, major mutation G197del was detected in 30% (7 out of 22) of patients with FH. In the Slavic population of St. Petersburg, no major mutations were detected. Only five mutations were identified in two families, while 24 were found in isolated families. These data are indicative of the lack of a strong founder effect for FH in the St. Petersburg population.

[On the seeming and real atherogenicity of LDLP-IgG immune complexes in blood plasma and the arterial wall].

LDLP-antibody immune complexes and free LDLP were isolated from the serum and aortal wall of people who had died of myocardial infarction; their atherogenicity was compared on the basis of their capture by mouse peritoneal macrophages. The experiment showed that the capture of serum and aortal autoimmune LDPT-antibody complexes was approximately 2.5 times higher than that of free serum lipoproteins (mostly native ones). However, the capture of free (mostly modified) aortal LDLP was approximately 3.6 times higher than that of aortal immune complexes. According to the data received, the comparative atherogenicity of immune complexes and free lipoproteins can be ranked in the following order: modified LDLP --> modified LDLP-IgG complex --> native LDLP. The study shows that LDLP-antibody immune complexes formed in a rabbit's organism get extremely quickly eliminated from bloodstream, probably due to their active capture by reticuloendothelial system cells. The authors suggest that the formation of antilipoprotein autoantibodies and lipoprotein-antibody complexes is a protective response of the organism to appearance of highly atherogenic modified lipoproteins directed towards the weakening of the atherogenicity of such lipoproteins and the intensification of their elimination from bloodstream.

Changes in the lipid composition of blood plasma and liver in rats induced by severe psychic trauma.

The concentration of high-density lipoprotein cholesterol and triglycerides in rat serum sharply decreased after psychic trauma caused by life hazard. The content of these substances remained unchanged for not less than 1 week after trauma. The concentration of high-density lipoprotein cholesterol was low, while serum content of triglycerides increased 6 weeks after trauma. The concentration of high-density lipoprotein cholesterol significantly decreased after repeated psychic trauma. These changes were accompanied by a sharp increase in the concentration of triglycerides in the serum. Total cholesterol concentration in the liver decreased under these conditions.

Cytotoxic effect of low-density lipoproteins.

The cytopathogenic effect of various modified lipoproteins on cultured peritoneal macrophages was studied in vitro. After minor peroxide modification lipoproteins induced apoptosis of macrophages. Immune complexes containing oxidized lipoproteins caused cell necrosis.

[Measurement of blood homocysteine by high performance liquid chromatography (HPLC)]. / Opredelenie soderzhaniia gomotsisteina plazmy krovi metodom vysokoéffektivnoi zhidkostnoi khromatografii (VEZhKh).

Hyperhomocysteinemia is an independent risk factor for atherosclerosis and vascular occlusive diseases. Measurements of total homocysteine (Hcy) require an accurate reproducible method. A high-performance liquid chromatographic (HPCL) method for evaluating plasma Hcy after reduction with 2-mercaptoethanol and precolumn derivatization with iodoacetic acid and o-phthaldialdehyde is described. The resultant derivatives were separated on reverse-phase column C18 in the isocratic HPCL mode with fluorimetric detection. The detection limit for Hcy is 0.8 mumol/liter. The concentration of Hcy after overnight fasting was increased significantly (p < 0.02) in the patients in comparison with the control (11.7 +/- 1.1 vs. 8.3 +/- 0.5 mumol/liter). The method can be used for measuring the concentrations of asparaginic acid, glutamic acid, cysteine, asparagine, serine, and glutamine.

Simultaneous determination of several amino acids, including homocysteine, cysteine and glutamic acid, in human plasma by isocratic reversed-phase high-performance liquid chromatography with fluorimetric detection.

A method for the simultaneous measurement of two biologically important thiol compounds cysteine and homocysteine and five amino acids including neurotransmitters aspartate and glutamate is reported. This method utilized derivatization of compounds with o-phthalaldehyde in the presence of 2-mercaptoethanol following alkylation of the free sulfydryl group with iodoacetic acid followed by separation using reversed-phase high-performance liquid chromatography. These o-phthalaldehyde-2-mercaptoethanol-labeled compounds were separated within 30 min on a Spherisorb ODS-2 column with isocratic elution using 17% methanol, 0.04 M sodium phosphate buffer (pH 7.0), 0.002 M Na2EDTA and detected fluorimetrically (excitation 340 nm, emission 450 nm). Using this method, the concentrations of homocysteine, cysteine, glutamic acid. aspartic acid, asparagine, serine and glutamine in human plasma were determined.

Receptor-mediated transfer of DNA--galactosylated poly-L-lysine complexes into mammalian cells in vitro and in vivo.

With the goal of developing non-viral techniques for exogenous gene delivery into mammalian cells, we have studied receptor-mediated gene transfer using complexes of plasmid DNA and galactosylated poly-L-lysine, poly(L-Lys)Gal. To evaluate the optimal parameters for efficient gene transfer into human hepatoma HepG2 cells by the DNA-poly(L-Lys)Gal complexes, the bacterial reporter genes lacZ and cat were used. Examination of the reporter gene expression level showed that the efficiency of DNA delivery into the cells depends on the structure of DNA--poly(L-Lys)Gal complexes formed at various ionic strength values. The efficiency of DNA transfer into the cells also depends on DNA/poly(L-Lys)Gal molar ratio in the complexes. Plasmid vector carrying human apolipoprotein A-I (apoA-I) gene was injected as its complex with poly(L-Lys)Gal into rat tail vein. Some level of ApoA-I was detected in the serum of the injected rats. Also, the human apoA-I-containing plasmid was found to be captured specifically by the rat liver cells and transported into the cell nuclei, where it can persist as an episome-like structure for at least a week. After repeated injections of DNA--poly(L-Lys)Gal complexes, the level of human ApoA-I in rat serum increases, probably, due to accumulation of functional human apoA-I gene in the liver cell nuclei. The data seem to be useful for the development of non-viral approaches to gene therapy of cardiovascular diseases.

[Mechanism of acceleration of acid hemolysis of the E-form of serum albumin]. / Mekhanizm uskoreniia kislotnogo gemoliza E-forma syvorotochnogo al'bumina.

The influence of human and bovine serum albumin on the proton-mediated lysis of human, rabbit and sheep erythrocytes was studied. An essential acceleration of hemolysis (2-7-fold) by the action of albumin was observed only at pH values below 4.0, i.e. at values at which the transition of albumin to the E conformation occurs. It was shown in the experiments with fatty-acid-free albumin and the protein loaded by palmitate that the accelerating effect of albumin was due to the hemolytic action of fatty acids released from the protein. As a result of the proton potentiation of detergent-dependent hemolysis, fatty acids released from E-albumin become more potent hemolytic agents.