The development of renal dysfunction in patients with rheumatoid arthritis (RA) is due to the presence and severity of autoimmune disorders, chronic systemic inflammation, a multiplicity of comorbid conditions, and pharmacotherapy features. The most important parameter that describes the general condition of the kidneys is glomerular filtration rate (GFR). This review presents the data on the possibilities of modern methods for determining estimated GFR (e-GFR) and the specificity of their use in various clinical situations that accompany the course of RA. For the initial assessment of GFR in patients with RA it is advisable to use the measurement of e-GFR based on serum creatinine concentration using the CKD-EPI equation (2009) (with or without indexing by body surface area). In cases where the e-GFR equations are not reliable enough or the results of this test are insufficient for clinical decision making, the serum cystatin C level should be measured and the combined GFR calculation based on creatinine and cystatin C should be used.

Background:Objectives:To assess the potential role of angiopoietin-like protein type 4 (ANGPTL4) in metabolic disorders caused by inflammation in rheumatoid arthritis (RA).Methods:The study included 88 patients with significant RA, 64 patients with other rheumatic diseases (RD) (36 patients with osteoarthritis (OA); 28 patients with psoriatic arthritis (PsA); 17 patients with ankylosing spondylitis (AS)) and 32 healthy individuals. Estimation of ANGPTL4 was carried out by enzyme immunoassay using the commercial test system “RayBio Human ANGPTL4 ELISA Kit” (RayBiotech, USA) in blood serum. Levels of ESR, CRP, RF, antibodies to cyclic citrullinated peptide (anti-CCP) and modified vimentin (anti-MCV) in the ELISA test were determined for all patients with RA.Results:The level of ANGPTL4 in the blood serum of patients with RA was significantly higher than in healthy people (p <0.001) and patients with other RD (p = 0.012 compared with OA; p = 0.046 with PsA; p = 0.008 with AS). ANGPTL4 indices in patients with RA correlated with the age of onset of RA (r = -0.658, p <0.001), disease activity according to DAS-28 (r = 0.449, p = 0.001), level of education (r = 0.235, p = 0.029), dose of glucocorticoid hormones (r = 0.321, p = 0.009) and methotrexate (r = -0.496, p = 0.05), the presence of osteopenia (r = 0.44), signs of kidney damage - proteinuria (r = 0.309, p = 0.037) and hypoalbuminemia (r = 0.386, p = 0.022), as well as with CRP levels (r = 0.488, p = 0.003), ESR (r = 0.458, p = 0.002), serum vitamin D (r = -0.417) and urinary calcium when recalculated to creatinine (r = 0.797, p = 0.032).Patients with RA showed a high frequency of insulin resistance (according to the HOMA-IR index) (1.27 [0.84–1.62] in patients with RA; 0.76 [0.44–1.02] in healthy individuals; p <0.001) and the presence of coronary heart disease, as well as a positive correlation between disease activity (according to DAS-28) and insulin resistance (according to the HOMA-IR index) (p = 0.033).Higher values of C-reactive protein (p = 0.04) and serum ANGPTL4 levels (p = 0.042, compared with patients with RA without type 2 diabetes; p = 0.026, compared with healthy individuals) were determined in the group of patients with RA with the presence of type 2 diabetes. ANGPTL4 acts as an inhibitor of lipoprotein lipase. His contribution to the development of dyslipidemia in RA can be demonstrated by the results we obtained when comparing groups of patients with / without signs of metabolic syndrome (MS). A positive correlation between ANGPTL4 and triglyceride levels (r = 0.42, p = 0.018) was found. An increase in the level of ANGPTL4 in blood serum of patients with RA with MS (p = 0.027 compared with RA without MS) can predict the development of cardiac pathology in this group of patients.Conclusion:ANGPTL4 is directly involved in the regulation of glucose homeostasis, lipid metabolism, and insulin sensitivity. Cardiovascular diseases associated with atherosclerosis, insulin resistance and metabolic syndrome are known as the most common extraarticular manifestations of RA; the study of the role of ANGPTL4 in metabolic disorders caused by inflammation can show a new direction in the development of laboratory and therapeutic technologies in RA.Disclosure of Interests:None declared

Background:New serological markers that can serve as objective indicators of osteoporotic changes in patients with rheumatoid arthritis (RA) are being currently searched [1, 2, 3, 4, 5].Objectives:To reveal the connection between the concentrations of serum angiopoietin-like protein type 4 (ANGPTL4) and the decrease in bone mineral density (BMD) in patients with RA.Methods:114 patients with reliable RA (90.4% of women, 9.6% of men) aged 21 to 80 years (mean age 55.4 ± 11.2 years old, disease duration - 11.18 ± 9.03 years, positive for rheumatoid factor (RF-IgM) - 63.2%, positive for anti-citrullinated protein antibody (ACPA) - 59.7%) were examined using a bone X-ray densitometer LUNAR DPX (GE, USA). Patients with an advanced clinical stage - 49%, moderate activity according to DAS28 - 58.8%, II-III radiological stage - 85.1% and functional class II - 64.9% prevailed. ANGPTL4 measurement in blood serum was carried out by enzyme immunoassay using a commercial test system “RayBio Human ANGPTL4 ELISA Kit” (RayBiotech, USA). ESR, RF, as well as C-reactive protein (CRP), ACPA, and antibodies to modified vimentin (anti-MCV) in an ELISA test were determined in all RA patients.Results:ANGPTL4 indices in RA patients correlated with the CRP level (r = 0.34, p = 0.001) and the DAS-28 (r = 0.29, p = 0.002). There was no correlation between the level of ANGPTL4 and the intake of glucocorticoids, both at the time of the study (p = 0.678) and with their long-term (more than 3 months) use (p = 0.097). There was a negative correlation of weak strength between ANGPTL4 and the dose of non-steroidal anti-inflammatory drugs (r = -0.21, p = 0.035). There was no correlation between ACPA, anti-MCV, and ANGPTL4 levels (p> 0.1 and p = 0.084). A direct correlation was found between the level of ANGPTL4 and the presence of osteopenia in RA patients (r = 0.43, p = 0.036), as well as a negative correlation between ANGPTL4 and bone mineral density in the spine (BMD L1-4, r = -0.631, p <0.001), but not in the femur (p> 0.05). Densitometry data also allowed to establish a negative correlation between low values of the T-criterion and increased titers of anti-MCV (r = -0.51, p = 0.029), but not ACPA (p = 0.276). It has previously been noted that anti-MCV are able to activate osteoclasts with a consequent decrease in periarticular BMD.Conclusion:The absence of a relationship between anti-MCV and the level of ANGPTL4 may indicate different mechanisms of osteoporosis development and localization of osteoporotic changes in groups of anti-MCV or ANGPTL4 positive patients with RA.References:[1]Ramli FF, Chin KY. A Review of the Potential Application of Osteocyte-Related Biomarkers, Fibroblast Growth Factor-23, Sclerostin, and Dickkopf-1 in Predicting Osteoporosis and Fractures. Diagnostics (Basel). 2020;10(3):145. doi: 10.3390/diagnostics10030145[2]Aleksandrov V., Aleksandrov A. Angiopoetin-like protein type 3 as an indicator of rheumatoid inflammation and resorption of bone tissue in rheumatoid arthritis. Ann Rheum Dis. 2020;79(s1):1340. doi: 10.1136/annrheumdis-2020-eular.2174[3]Nagy EE, Nagy-Finna C, Popoviciu H, Kovács B. Soluble Biomarkers of Osteoporosis and Osteoarthritis, from Pathway Mapping to Clinical Trials: An Update. Clin Interv Aging. 2020;15:501-518. doi: 10.2147/CIA.S242288[4]Aleksandrov A.V., Alekhina I.Y., Aleksandrova N.V., Shilova L.N., Aleksandrov V.A. High antibody titers to cyclic citrullinated vimentin promote the development of periarticular osteoporosis in patients with rheumatoid arthritis. Osteoporosis International. 2019; 30(s2):680.[5]Donati S, Ciuffi S, Palmini G, Brandi ML. Circulating miRNAs: A New Opportunity in Bone Fragility. Biomolecules. 2020;10(6):927. doi: 10.3390/biom10060927Disclosure of Interests:None declared.

Проведена оценка отдаленных результатов применения метода низкочастотной магнитотерапии (НМТ) при проведении восстановительного лечения больных остеоартрозом (ОА). Обследовано 83 пациента с ОА (16 мужчин и 67 женщин в возрасте от 28 до 73 лет), проходящих курсовое (21 день) лечение в санаторно-курортных условиях. Все больные ОА были разделены на две группы, сопоставимые по половому составу, возрасту, длительности, активности заболевания и фактору фоновой терапии: основную (n=50) -с применением метода НМТ, и контрольную (n=33) -группа плацебо. Результаты изучения лечебного воздействия НМТ свидетельствуют о высокой эффективности данного метода и характеризуются достоверными изменениями индекса WОMАС (в основной группе уменьшение суммарного индекса WОMАС на 64,8%, в контрольной группе -на 28,6%), увеличением сроков ремиссии заболевания (ремиссия более 9 месяцев отмечалась у 18% пациентов из основной группы и у 6,1% из контрольной группы), снижением частоты рецидивов и частоты приема нестероидных противовоспалительных препаратов больными ОА. Применение НМТ на санаторно-курортном этапе соответствует условиям целенаправленной реабилитации больных ОА и позволяет улучшить отдаленные результаты терапии больных данного профиля. Ключевые слова: остеоартроз, низкочастотная магнитотерапия, восстановительная терапия. The results of the study of the therapeutic effects of LFMT demonstrate the high efficiency of this method and are characterized by significant changes of WOMAC index (in the primary group -decrease in total WOMAC index by 64.8%, in the control group -28.6%), the increase in terms of disease remission (remission more than 9 months was observed in 18% of patients in the primary group and 6.1% in the control group), a decrease in the frequency of relapses and frequency of intake of NSAID in OA patients. Application of LFMT on sanatorium stage corresponds to the conditions of targeted rehabilitation of patients with OA and improves long-term results of treatment of patients of this type. ASSESSMENT ОF LONG-TERM RESULTS OF LOW-FREQUENCY MAGNETIC

BackgroundIn the pathogenesis of SLE an important place is given to immune mechanisms with many uncertain aspects. Adenosine deaminase (ADA), 5-nucleotidase (5-NT), adenosine kinase (ADK) and xanthine oxidase (XO) are the main enzymes of adenine branch of purine metabolism (PM), the activity of which is closely related to the immunological processes in the body. The role of antibodies to enzymes PM in systemic lupus erythematosus (SLE) is not defined and poorly studied.ObjectivesThe purpose of our work was to study antibodies to enzymes of adenine branch of PM in SLE patients and to detect correlations between studied antibodies and clinical and laboratory indices of pathological process.Methods30 healthy individuals aged 18 to 40 years (20 women and 10 men) and 60 SLE patients aged 22 to 58 years (55 women and 5 men) were included into the research. The diagnosis of SLE was verified using the ACR criteria of the 1997. The object of research was blood serum. IgG antibodies to ADA (anti-ADA), 5-NT (anti-5NT), ADC (anti-ADC) and XO (anti-XO) were determined in the method developed by us for indirect ELISA-assay using an immobilized form of the correlative enzyme as antigen matrix. Positive results were considered greater than 2 standard deviations of figures obtained during the examination of healthy persons (0.106 Unit for anti-ADA; 0.1 Unit for anti-5NT; 0.47 Unit for anti-ADC; 0.097 U for the anti-XO). The results were expressed as mean ± σ, differences were considered significant when p<0.05. Person correlation coefficient (r) was also used.ResultsAccording to the results of the research the number of SLE patients with elevated levels of anti-ADA was 51.6%, anti-5NT - 41.7%, anti-ADK - 46,7%, the anti-XO - 53.3%. Comparison between the positive and negative for the presence of anti-ADA groups of patients with SLE showed a statistically significant increase in the detection rate of chronic headaches (p=0.01), lymphopenia (p=0.025) and the definition of increased values of antibodies to phospholipids (p=0.014).Comparison between the positive and negative for the presence of blood serum anti-5NT groups of SLE patients showed an increase in the frequency of kidney damage (p=0.031) and vessels (p=0.053). Analysis of anti-5NT in relation to laboratory data allowed to identify a number of statistically significant correlations: with proteinuria (r=0,27; p=0,039), leukocyturia (r=0,35; p=0,012) and red blood cell (r=0,29; p=0,026). These data allow us to consider the anti-5NT as an additional indicator of lupus nephropathy.Among patients with the presence of anti-ADK a significant number of patients with vascular disease (p=0,023) was revealed. A bit more often, but not statistically significant, patients with the presence of anti-ADC pulmonary injury (p=0,113) and the autonomic nervous system (p=0,124) were observed.Comparison between the positive and negative for the presence of anti-CA groups of patients with SLE demonstrated a statistically significant increase in the frequency of signs of kidney (p=0.032) and blood...