β-adrenoreceptor (ADRB) ligands are actively used in the therapy of bronchopulmonary and cardiovascular diseases. When using these drugs, it is important to assess changes in ADRB content in different tissues. In most cases, the direct measurement of ADRB content in lung and heart cells is not possible. ADRB2 content in peripheral blood lymphocytes (or mononuclear cells) was shown to correlate with that in myocardial cells. It has been suggested that blood lymphocytes can be used to monitor ADRB content in solid organs. However, the estimation of ADRB1 content in myocardium from its content in peripheral lymphocytes is not possible due to the low content of ADRB1 in lymphocytes. In the present study, we performed simultaneous determination of ADRB1 and ADRB2 both in the total population of PBMCs and in isolated subpopulations of monocytes, T-lymphocytes, and NK-cells from 23 healthy donors using the modified radioligand method. The highest amount of ADRB2 was detected in NK cells, followed by PBMCs, monocytes, and T cells. The content of these receptors in all blood cell subpopulations was significantly correlated with each other, suggesting the possibility of using PBMCs to monitor ADRB2 in solid organs. For the first time, ADRB1 was detected in monocytes and NK cells.

The detection of autoantibodies against the β1-adrenergic receptor (ADRB1 Ab) in the blood of patients and the monitoring of the levels of these antibodies is an urgent need in clinical practice. The solid-phase enzyme-linked immunosorbent assay (ELISA), using ADRB1 in native conformation as antigen, seems to be the most suitable for this task. We have previously tested various amphipathic polymers for their ability to solubilize ADRB1 in the form of nanodiscs so that ADRB1 retains its antigenic properties. The aim of the present work was to investigate the ligand binding properties of ADRB1 in nanodiscs prepared with amphipathic polymers such as UltrasoluteTM Amphipol (UA17) and AASTY 11-45 and to determine the size of the nanodiscs by dynamic light scattering. The binding of the ligands isoproterenol (agonist) and cyanopindolol (antagonist) was assessed by their ability to compete with recombinant hAB2367 antibodies specific for the second extracellular loop of ADRB1 in ELISA. It was found that ADRB1 solubilized with UA17 and AASTY 11-45 retained its ligand-binding properties. This fact supports the assumption that ADRB1 retains its native structure in nanodiscs. The size of nanodiscs prepared with UA17 was determined for the first time by dynamic light scattering. In the range of polymer concentrations from 0.0625% to 0.5%, no significant differences were observed in the size of the nanodiscs, which varied between 10 and 16 nm.

The development of a reliable and easily used diagnostic test for measuring autoantibodies to ?1-adrenergic receptor (?1ADR Ab) in patient blood is an unmet clinical need. The enzyme-linked immunosorbent assay (ELISA) is considered as the most appropriate method for this task. In ELISA, the use of peptides corresponding to various fragments of amino acid sequence of ?1ADR as antigens leads to inadequate results as β1ADR Ab appear to recognize conformationally dependent epitopes that are generated during the formation of unique tertiary structure of the receptor. Isolation of ?1ADR preserving the native conformation and functional characteristics is a quite challenging task. A promising approach to address this task is the use of amphipatic polymers capable of forming nanodiscs, it permits to successfully solubilize membrane proteins. In order to obtain the preparations of solubilized β1ADR that can be used as antigens in ELISA we have tested 17 various amphipatic polymers. The best relative solubilization values (RSV) were obtained using UltrasoluteTM Amphipol 17 (87%) and 18 (62%), as well as by AASTY 11-45 (76%), 11-50 (77%) and 6-50 (78.5%).

Во многих тканях и клетках человека присутствуют как β1-, так и β2-адренорецепторы, информация о содержании и динамике поведения кото- рых часто является клинически значимой. В настоящем исследовании предложена методика раздельного определения обоих типов адреноре- цепторов на основе радиолигандного анализа с использованием 125I-йодоцианопиндолола, включающая проведение трех измерений: 1) без лигандов-конкурентов; 2) в присутствии селективного лиганда ICI 118,551 (0,25 мкМ); 3) в присутствии двух селективных лигандов ICI 118,551 и CGP 20712 (по 0,25 мкМ каждого). Методика протестирована на модельной системе из двух трансгенных линий клеток с экспрессией реком- бинантных β1- и β2-адренорецепторов. При соотношении количества β1-адренорецепторов к β2-адренорецепторам 1:10 погрешность измере- ния составляет около 15%. Анализ 9 клеточных линий, представляющих различные типы клеток крови, показал наличие β2-адренорецепторов в клетках Daudi, Raji, Dami, K-562, HL-60, U-937 и THP-1 и их отсутствие в Т-лимфоцитарных клетках Jurkat и MOLT-4. β1-адренорецепторы достоверно зарегистрированы лишь в клетках THP-1 моноцитарного происхождения. В остальных клетках, за исключением линии Dami, их количество оказалось ниже порога детекции, оцениваемого на уровне 250 молекул на клетку. Измерения, выполненные на мононуклеарных клетках периферической крови здоровых доноров, продемонстрировали присутствие β2-адренорецепторов в диапазоне от 1000 до 2500 моле- кул на клетку, тогда как содержание β1-адренорецепторов во всех случаях находилось на грани или за гранью порога детекции. По-видимому, изучение β1-адренорецепторов в дальнейшем следует проводить на отдельных фракциях клеток крови, в частности на фракции моноцитовβ1- and β2-adrenergic receptors are presented in various human tissues and cells, while the information of their content and dynamic behavior is oftenly considered as clinically significant. In this study, a method for the separate determination of both types of adrenoceptors based on radioligand binding analysis using 125I iodocyanopindolol is proposed, comprising three measurements: 1) without competing ligands; 2) in the presence of selective ligand ICI 118,551 (0.25 μM); 3) in the presence of two selective ligands ICI 118,551 and CGP 20712 (0.25 μM each). The technique was tested on a model system of two transgenic cell lines with the expression of recombinant β1- and β2-adrenergic receptors. If the ratio of the number of β1-adrenergic receptors to β2-adrenergic receptors is 1:10, the measurement error is about 15%. Analysis of 9 cell lines representing different types of blood cells showed the presence of β2-adrenergic receptors in Daudi, Raji, Dami, K-562, HL-60, U-937 and THP-1 cells and their absence in Jurkat and MOLT-4 cells. β1-adrenergic receptors are reliably registered only in THP-1 cells of monocytic origin. In the remaining cell lines, with the exception of Dami, the number of β1-adrenergic receptors was found below the detection limit, estimated as 250 molecules per cell. Measurements performed on the peripheral blood mononuclear cells of healthy donors showed the presence of β2-adrenergic receptors in the range from 1000 to 2500 molecules per cell, while the content of β1-adrenergic receptors in all cases appeared to be on the border or beyond the detection limit. Apparently, further study of β1-adrenergic receptors should be performed on the blood cells isolated fractions, on monocytes in particular

Current management of patients with acute coronary syndrome (ACS) includes a dual antiplatelet therapy with acetylsalicylic acid and a platelet P2Y12 receptor inhibitor. For patients without a high risk of bleeding, prasugrel and ticagrelor are preferred, since their effect is more pronounced, less dependent on metabolism of a specific patient, and occurs faster that the effect of clopidogrel. The prescription rate of platelet glycoprotein IIb/IIIa (GP IIb / IIIa) receptor inhibitors has considerably decreased. However, these drugs remain relevant in percutaneous coronary interventions in patients with a high risk of coronary thrombosis or a massive coronary thrombus, in thrombotic complications of the procedure, and in the "no-reflow" phenomenon. The intravenous route of GP IIb / IIIa inhibitor administration provides their effectiveness in patients with difficulties of drug intake or with impaired absorption of oral medications. This review presents clinical and pharmacological characteristics of various GP IIb / IIIa inhibitors and data of randomized clinical studies and registries of recent years that evaluated results of their use in patients with ACS.

The existing biological models of diffuse alveolar damage (DAD) in mice have many shortcomings. To offset these shortcomings, we have proposed a simple, nonsurgical, and reproducible method of unilateral total damage of the left lung in ICR mice. This model is based on the intrabronchial administration of a mixture of bacterial lipopolysaccharide (LPS) from the cell wall of S. enterica and α-galactosylceramide (inducing substances) to the left lung. Using computer tomography of the lungs with endobronchial administration of contrast material, we have been able to perform an operative intravital verification of the targeted delivery of the inducer. The model presented is characterized by more serious and homogeneous damage of the affected lung compared to the existing models of focal pneumonia; at the same time, our model is characterized by longer animal survival since the right lung remains intact. The model is also characterized by diffuse alveolar damage of the left lung, animal survival of 100%, abrupt increases in plasma levels of TNFa, INFg, and IL-6, and significant myocardial overload in the right heart. It can be used to assess the efficacy of innovative drugs for the treatment of DAD and ARDS as the clinical manifestations that are developed in patients infected with SARS-CoV-2. Morphological patterns of lungs in the noninfectious (“sterile”) model of DAD induced by LPS simultaneously with α-galactosylceramide (presented here) and in the infectious model of DAD induced by SARS-CoV-2 have been compared. The DAD model we have proposed can be widely used for studying the efficacy of candidate molecules for the treatment of infectious respiratory diseases, such as viral pneumonias of different etiology, including SARS-CoV-2.

In diabetes-associated hyperlipidemia, free fatty acids (FFAs) are thought to induce insulin resistance and endothelial dysfunction leading to vascular injury and cardiovascular T2DM complications. However, evidence is scarce regarding the effects of FFA on vascular endothelial barrier. We used human umbilical vein endothelial cells (HUVEC) to model, in vitro, the endothelial barrier and reveal its responses to experimental hyperlipidemia induced by long-term treatment with palmitic acid in complex with albumin. Palmitate was continuously present in the growth medium at 0.8 mM to reproduce FFA levels typical for T2DM. We developed conditions to maintain the HUVEC monolayers in the presence of the high palmitate concentration for up to 2 weeks by adding exogenous carnitine to facilitate mitochondrial β-oxidation of FFA. In this model system, palmitate readily augmented the transendothelial electric resistance (TER) of HUVEC via increased NO production by endothelial NO-synthase (eNOS). Western blots showed that palmitate neither disturbed insulin signaling cascade towards eNOS nor upregulated eNOS expression. After the initial 3-4-day rise in TER, further treatment with palmitate led to barrier stabilization and attenuation as compared to FFA-free conditions. This later phase was associated with increased ROS and malondialdehyde (MDA) accumulation, both prevented by the mitochondria-targeted antioxidant SkQ1. Treatment of HUVEC with exogenous MDA impaired the TER and barrier suggesting that accumulation of MDA-modified proteins may contribute to the barrier dysfunction upon long-term experimental hyperlipidemia. Altogether, obtained evidence suggests that prolonged exposure of vascular endothelium to high levels of palmitate compromises endothelium barrier capacity and insulin-mediated eNOS regulation turning the enzyme permanently active. Disclosure M. Samsonov: None. V. P. Shirinsky: None. N. Podkuychenko: None. A. Y. Khapchaev: None. T. Vlasik: None. V. Lankin: None. M. Skulachev: Other Relationship; Self; Mitotech LLC. I. Stafeev: None. A. V. Vorotnikov: None. M. V. Shestakova: None. Funding Russian Science Foundation (19-15-00361)

Hyperlipidemia manifested by high blood levels of free fatty acids (FFA) and lipoprotein triglycerides is critical for the progression of type 2 diabetes (T2D) and its cardiovascular complications via vascular endothelial dysfunction. However, attempts to assess high FFA effects in endothelial culture often result in early cell apoptosis that poorly recapitulates a much slower pace of vascular deterioration in vivo and does not provide for the longer-term studies of endothelial lipotoxicity in vitro. Here, we report that palmitate (PA), a typical FFA, does not impair, by itself, endothelial barrier and insulin signaling in human umbilical vein endothelial cells (HUVEC), but increases NO release, reactive oxygen species (ROS) generation, and protein labeling by malondialdehyde (MDA) hallmarking oxidative stress and increased lipid peroxidation. This PA-induced stress eventually resulted in the loss of cell viability coincident with loss of insulin signaling. Supplementation with 5-aminoimidazole-4-carboxamide-riboside (AICAR) increased endothelial AMP-activated protein kinase (AMPK) activity, supported insulin signaling, and prevented the PA-induced increases in NO, ROS, and MDA, thus allowing to maintain HUVEC viability and barrier, and providing the means to study the long-term effects of high FFA levels in endothelial cultures. An upgraded cell-based model reproduces FFA-induced insulin resistance by demonstrating decreased NO production by vascular endothelium.

Autoantibodies to 1-adrenergic receptor may play a role in the development of certain cardiovascular system diseases.Synthetic peptide-based enzyme-linked immunosorbent assay (eliSA), traditionally used for the detection of such antibodies, does not allow to obtain adequate data, probably due to the poor similarity of peptide conformations to the spatial structure of the extracellular regions.Aim of the study: to improve the peptide-based eliSA method for the detection of autoantibodies to 1 adrenergic receptor by a separate determination of the igG1, igG2, igG3, igG4, igM and igA autoantibody isotypes.Material and methods: a modification of the eliSA method with peptides corresponding to the sequences of the 1-adrenergic receptor first and second extracellular loops, and secondary antibodies specific to the abovementioned human immunoglobulin isotypes.the method has been tested on a panel of samples obtained from patients with dilated cardiomyopathy (dcM), arrhythmia and coronary heart disease.ResultS: small excess of the signal mean values of individual antibody isotypes have been recorded for some groups of patients in comparison with the group of healthy volunteers.however, these differences were not statistically significant.the proportion of signals «above the 1 ооо «МонА», ул.кастанаевская, 38, стр. 1, Москва, 121108, российская федерация; 2 фГБу «национальный медицинский исследовательский центр кардиологии» Минздрава россии, ул.3-я черепковская, 15а, Москва, 121552, российская федерация Резюме Аутоантитела к 1-адренорецептору могут играть важную роль в развитии некоторых заболеваний сердечно-сосудистой системы.иммуноферментный анализ (ифА) с использованием синтетических пептидов, традиционно применяемый с целью детекции таких антител, не позволяет получать адекватные данные, вероятно, вследствие слабого сходства конформаций пептидов с пространственной структурой внеклеточных участков 1-адренорецептора.Цель исследования.усовершенствовать метод ифА для детекции аутоантител к 1-адренорецептору за счет раздельного определения аутоантител изотипов igG1, igG2, igG3, igG4, igM и igA.Материал и методы.предложена модификация метода ифА с использованием пептидов, соответствующих последовательностям первой и второй внеклеточных петель 1-адренорецептора, и вторых антител, специфических к вышеуказанным изотипам иммуноглобулинов человека.Метод опробован на панели образцов сыворотки крови, полученных от пациентов с дилатационной кардиомиопатией (дкМп), желудочковой аритмией и ишемической болезнью сердца.Результаты. для некоторых групп больных зафиксированы небольшие превышения средних значений сигналов отдельных изотипов антител по сравнению с группой здоровых добровольцев, однако эти отличия не являются статистически значимыми.доля сигналов «выше уровня нормы» в группе больных дкМп составила 21% для изотипа igG1 и от 6 до 16% для остальных изотипов, что весьма далеко от частоты встречаемости аутоантител к 1-адренорецептору (70-80%), наблюдаемой у больных дкМп при использовании функциональных методов анализа.в других группах доля таких сигналов не превысила 30% ни для одного изотипа антител.

Abstract Background Takotsubo cardiomyopathy (TTC) is an acute, life-threatening condition which is typically induced by stress and manifested by chest pain and ECG changes. The TTC prevalence among patients (pts) with acute coronary syndrome is 1.7–2.2%. The mortality rate from TTC is up to 8%. TTC is clinically indistinguishable from acute myocardial infarction (AIM). Differential diagnosis of TTC and AIM remains an unresolved problem. Recent studies have shown the differences in profiles of plasma microRNAs inTTC and AIM. Purpose To evaluate the possibility of differentiating TTC and AIM using a PCR-based semi-quantitative analysis of mRNAs, the plasma levels of which had been shown to be increased in patients with AIM (miR-1, miR-208a, miR-133a, miR-499a) and TTC (miR-16, miR-26a). Methods Plasma from 38 pts was used: 13 pts with confirmed TTC (12 women, 1 man), 25 pts with AIM (9w, 16m). For 10 pts with AIM, blood was collected twice: at 6 and 24 hours after the heart attack. The control arm comprised 40 healthy people from the same age group (12w, 28m). Plasma was obtained using the Cell-Free DNA blood collection tubes. Nucleic acids were separated using a modified Boom method. A semi-quantitative assessment of the mRNA levels was performed using dCq method with stem-loop qRT-PCR. Normalization for spiked synthetic cel-miR-39 and endogenous miR-23a was performed. Control of hemolysis was performed by measuring the ratio of miR-451 (specific for RBCs) and miR-23a (absent from RBCs). The statistical significance of differences between mRNA levels was assessed using Mann–Whitney test. Results No significant differences in the levels of miR-16, miR-26a and miR-208a in TTC group and control group have been found. Pts with AIM significantly differed from pts with TTC (p=0.0038 and 0.0002, respectively) and control pts (p=3.1x10–9 and 2,66x10–10) with the increased levels of cardiac-specific miR-1 and miR-133a. As compared to plasma levels at 6 hours after the heart attack, at 24-hour point the levels of these mRNAs were markedly reduced in 9 of 10 pts (mean reduction was 22.3-fold for miR-133a and 7.5-fold for miR-1). The correlation between changes in the levels of these mRNAs was high (Spearman correlation coefficient=0.89). Significant differences in plasma levels of miR-133a between pts with AIM and TTC were maintained even if blood was collected after 24 hours (p=0.007). For miR-16 and miR-26a, no significant differences between pts with AIM and TTC were found. The results of analysis of these mRNAs are affected to a substantial degree by the residual hemolysis due to their high content in blood cells. Conclusions It was shown that measuring the plasma levels of mRNAs miR-1 and miR-133a allows to distinguish TTC from AIM by excluding the diagnosis of TTC. The differential diagnosis is possible only within several hours after acute clinical symptoms and requires proper normalization and full compliance with the technical specifications.

P<0.05) as well as severity of arrhythmic episodes (AS 36.5 6 27.0 vs 8.3 6 12.3 in RVA 60, P<0.05).Conclusion: Prevention of acute bradycardia decreases the probability of arrhythmia development as well as the severity of induced arrhythmic events.P1022

According to current knowledge, autoantibodies against 1-adrenergic receptors may be involved in pathogenesis of different cardiovascular diseases and are mostly studied in patients with Chagas disease, dilated cardiomyopathy and heart rhythm disorders. They may play an important role in cardiomyocyte apoptosis, alteration of their chrono- and inotropic effects and electrophysiological characteristics. Their effects are transduced via 1-adrenergic receptors and depend on multiple factors as ligand properties, durability of its coupling with the receptor, amount of receptors on the cell surface, their affinity and conformation. Up to the present moment, reasons for autoimmune response and clinical significance of autoantibodies against 1-adrenergic receptors are not thoroughly understood. Autoantibodies against 1-adrenergic receptors can be removed from the bloodstream by immunoadsorption and thus development of validated methods of their identification is relevant.

OBJECTIVE:This study aimed to assess the level of anti-1-adrenergic receptor autoantibodies in patients with ventricular arrhythmias with no signs of organic heart disease and with presence of cardiovascular pathology in comparison with a group of healthy volunteers. MATERIAL AND METHODS:The study included 44 patients with ventricular arrhythmias with no signs of organic heart disease ("idiopathic"), 34 patients with diagnosed dilated cardiomyopathy (DCM) of inflammatory origin, 35 patients with coronary heart disease and ventricular arrhythmias, 12patients with coronary heart disease with no ventricular arrhythmias, and 19 healthy volunteers (control group). The level of autoantibodies against the 1-adrenergic receptor was determined by the developed competitive cell-based enzyme-linked immunosorbent assay (ELISA) and by the standard ELISA using peptides corresponding to the second extracellular loop of the 1-adrenergic receptor. RESULTS:Elevated level of autoantibodies detected by a competitive cell-based ELISA was observed in 62% of patients with DCM compared to 21% of healthy volunteers (p=0.0006). In patients with "idiopathic" ventricular arrhythmias, the level of 1-adrenergic receptor autoantibodies was lower than in healthy subjects (p=0.003). Coronary heart disease patients with or without ventricular arrhythmias exhibited no differences from the control group. The number of significantly positive signals in peptide-based ELISA did not exceed 10% in any of the groups. No correlation between the data from competitive cell-based ELISA and peptide-based ELISA was found. CONCLUSIONS:This study demonstrated that competitive cell-based ELISA technique can be applied for detection of 1-adrenergic receptor autoantibodies. The results in DCM patients generally correspond to the expected. Decreased level of autoantibodies in patients with "idiopathic" ventricular arrhythmias indicates that this disease is related to changes in the immune system. Such relation is not observed in the case of coronary heart disease patients.

AIM:To compare levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) in blood serum of patients from different cardiovascular risk categories.MATERIAL AND METHODS:Patients from Moscow prospective study database (n = 519) were divided into 4 cardiovascular risk categories according to present clinical recommendations (low, moderate, high, very high). Measurement of Lp-PLA2 concentration (mass) was performed using PLAC Test ELISA Kit. Measurement of Lp-PLA2 activity was made using PLAC Test for Lp-PLA2 Activity. Blood serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides (TG), lipoprotein (a) (Lp(a)), high sensitive C-reactive protein (hsCRP) and uric acid were also determined.RESULT:Preliminary analysis showed that associations between Lp-PLA2 mass and activity became more obvious in patients not treated with statins and patients without diabetes mellitus. So patients receiving statins and diabetics were excluded from final analysis. Lp-PLA2 mass and activity were lower in low cardiovascular risk category patients. There were no significant differences in Lp-PLA2 mass and activity between patients from moderate, high and very high risk categories. There was moderate correlation between Lp-PLA2 mass and Lp-PLA2 activity (r = 0.38, p < 0.00001). We did not find any correlation between Lp-PLA2 and hsCRP, Lp(a) levels, but detected moderate correlation between Lp-PLA2 mass and activity and TC, LDL-C. We also found a mild positive correlation between Lp-PLA2 mass and HDL-C levels. There was a positive correlation between Lp-PLA2 activity and TG, uric acid and negative correlation between Lp-PLA2 activity and HDL-C levels.CONCLUSION:In this group of nondiabetic patients not treated with statins both Lp-PLA2 activity and mass were similarly related to categories of cardiovascular risk.

Objectives: Small dense LDL particles (sdLDL) are generally accepted as coronary heart disease (CHD) risk factor. High atherogenic potential of sdLDL particles is often attributed to their elevated susceptibility to oxidative stress.

AIM:To assess the impact of combined treatment with simvastatin and ezetimibe or treatment with simvastatin only on lipoprotein-associated phospholipase A2 in patients with ischemic heart disease.METHODS:One hundred patients with angiographically documented coronary atherosclerosis took part in the investigation. Lp-PLA2 mass and cholesterol fractions were determined at baseline and after 6 months of treatment. Lp-PLA2 mass was determined by enzyme immunoassay method, using two highly specific monoclonal antibodies.RESULTS:Combined treatment with ezetimibe and simvastatin led to significantly greater declines in Lp-PLA2 and cholesterol fractions compared with treatment only with simvastatin: Lp-PLA2 decreased by 46 vs 38%, total cholesterol by 35 vs 28%, LDL cholesterol by 50 vs 40%, respectively (p<0.05). Combination therapy with ezetimibe and simvastatin 20 and 40mg/day proved to be as effective as monotherapy with simvastatin 80 mg/day on the effect on Lp-PLA2 mass and cholesterol fractions (p<0.05). Lp-PLA2 correlated positively with total cholesterol (r=0.28) and LDL-C (r=0.33).CONCLUSIONS:Combined treatment led to greater reduction of total cholesterol and LDL-C, as well as significantly reduced level of Lp-PLA2 mass. The latter can be considered as target for suppression of inflammation and achievement of stabilization of atherosclerotic plaque.

Aim. To asses the connection between lipoprotein-associated phospholipase A2 (Lp-PLA2) mass and activity levels and carotid atherosclerosis severity. Methods. 519 patients (162 men, 357 women, the mean age is 57.0 (51.0-64.0) years) were included in this study. Cardiovascular risk factors evaluation, clinical examination, biochemical analysis of blood with lipidemic profile, Lp-PLA2 levels determination and duplex ultrasound of the carotid arteries were performed. Results. Median Lp-PLA2 activity serum level was 202.4 (178.5 -232.6) nmol/min/ml. Median Lp-PLA2 mass serum level was 220.4 (197.1-247.2) ng/ml. There was a positive correlation between Lp-PLA2 activity (but not mass) levels and carotid atherosclerosis severity. The number of atherosclerotic plaques (р=0.01), maximal (p=0.03) and total (р=0.004) percent of carotid arteries stenoses were higher in patients, who had their Lp-PLA2 activity levels in the upper three quartiles compare to patients, who had their Lp-PLA2 activity levels in the lower quartile. Conclusion. Our data confirmed that there was a relation between Lp-PLA2 serum levels and carotid atherosclerosis severity. Lp-PLA2 activity was more associated with carotid atherosclerosis than Lp-PLA2 mass.