The aim of this study was to investigate cell source-dependent nucleic acids repertoire of diverse subpopulations of plasma extracellular vesicles (EVs). Blood plasma from nine healthy volunteers was used for the analysis. Samples of EVs were obtained by differential centrifugation of plasma. The application of high-sensitivity fluorescence-activated vesicles sorting (hs-FAVS) using fluorophore-conjugated anti-CD41-FITC (Fluorescein isothiocyanate) and anti-CD235a-PE antibodies allowed the isolation of three subpopulations of EVs, namely CD41+ CD235a-, CD41-CD235a+ and CD41-CD235a dim. The high purity (>97%) of the sorted subpopulations was verified by highsensitivity flow cytometry. Presence of nanosized objects in sorted samples was confirmed by combination of low-voltage scanning electron microscopy and dynamic light scattering. The amount of material in sorted samples was enough to perform Quantitative polymerase chain reaction (qPCR)-based nucleic acid quantification. The most prominent differences in the nucleic acid repertoire were noted between CD41+ CD235-vs. CD41-CD235a+ vesicles: the former contained significantly (p = 0.004) higher amount of mitochondrial DNA, and platelet enriched miR-21-5p (4-fold), miR-223-3p (38-fold) and miR-199a-3p (187-fold), but lower amount of erythrocyte enriched miR-451a (90-fold). CD41-CD235a+ and CD41-CD235a dim vesicles differed in levels of miR-451a (p = 0.016) and miR-21-5p (p = 0.031). Nuclear DNA was below the limit of detection in all EV subpopulations. The hs-FCM-based determination of the number of sorted EVs allowed the calculation of per single-event miRNA concentrations. It was demonstrated that the most abundant marker in CD41+ CD235a-subpopulation was miR-223-3p, reaching 38.2 molecules per event. In the CD41-CD235+ subpopulation, the most abundant marker was miR-451a, reaching 24.7 molecules per event. Taken together, our findings indicate that erythrocyte-and platelet-derived EVs carry different repertoires of nucleic acids, which were similar to the composition of their cellular sources.

Background. The need to study the population immunity to the SARS-CoV-2 virus is due to the intensive spread of COVID-19 and the implementation of immunoprophylaxis of this infection. The identification of the features of the formation of immunoresistance in organized military collectives will allow us to predict the development of the epidemic situation, including among comparable population groups. Aims the study of population immunity to the SARS-CoV-2 virus in the context of the COVID-19 pandemic against the background of specific immunoprophylaxis in organized military collectives. Methods. According to epidemiological indications, an epidemiological study of collective immunity to the SARS-CoV-2 virus was conducted against the background of vaccination among cadets of military educational organizations. The study involved 497 people, divided into groups by epidemiological and vaccination history for COVID-19, blood groups and Rh factor. The assessment of the immunity intensity was carried out by the levels of class G immunoglobulins (IgG) to SARS-CoV-2 in the blood serum by the method of solid-phase enzyme immunoassay. Results. Seroprevalence in the total sample was 92.6%. The highest rates were observed among vaccinated patients: those who were not ill and vaccinated 99.0 0.7%, those who were ill and vaccinated-100% (mean geometric antibody titers 1:2234 and 1:4399). Among the ill, unvaccinated individuals, the seroprevalence index was 84.5 3.2% (1:220). Among those who were not ill, not vaccinated 8.2 3.1% (1:113), which may indicate a hidden course of the epidemic process in the team. A negative immune response was more common (tSt = 2.01; p 0.05) in individuals A(II)Rh+ blood group. The highest proportion of maximum antibody titers (1:32001:6400) was determined in AB(IV) individuals. Rh-blood groups (tSt=2.21; p 0.05). Conclusions. For the first time, the formation of combined immunity with the highest concentrations of specific antibodies was revealed in patients who have been ill and vaccinated has been revealed, which allows us to recommend vaccination to those who have suffered from COVID-19. The emergence of post-infectious immunity in organized groups with a latent epidemic process has been established. The relationship between the intensity of immunity with blood groups and the Rh factor was found.

Coronavirus disease (COVID-19) has become a global pandemic. COVID-19 patients need immediate diagnosis and rehabilitation, which makes it urgent to identify new protein markers for a prognosis of the severity and outcome of the disease. The aim of this study was to analyze the levels of interleukin-6 (IL-6) and secretory phospholipase (sPLA2) in the blood of patients regarding the severity and outcome of COVID-19 infection. The study included clinical and biochemical data obtained from 158 patients with COVID-19 treated at St. Petersburg City Hospital No. 40. A detailed clinical blood test was performed on all patients, as well as an assessment of IL-6, sPLA2, aspartate aminotransferase (AST), total protein, albumin, lactate dehydrogenase (LDH), APTT, fibrinogen, procalcitonin, D-dimer, C-reactive protein (CRB), ferritin, and glomerular filtration rate (GFR) levels. It was found that the levels of PLA2, IL-6, APTV, AST, CRP, LDH, IL-6, D-dimer, and ferritin, as well as the number of neutrophils, significantly increased in patients with mild to severe COVID-19 infections. The levels of IL-6 were positively correlated with APTT; the levels of AST, LDH, CRP, D-dimer, and ferritin; and the number of neutrophils. The increase in the level of sPLA2 was positively correlated with the levels of CRP, LDH, D-dimer, and ferritin, the number of neutrophils, and APTT, and negatively correlated with the levels of GFR and lymphocytes. High levels of IL-6 and PLA2 significantly increase the risk of a severe course by 13.7 and 2.24 times, and increase the risk of death from COVID-19 infection by 14.82 and 5.32 times, respectively. We have shown that the blood levels of sPLA2 and IL-6 increase in cases which eventually result in death and when patients are transferred to the ICU (as the severity of COVID-19 infection increases), showing that IL-6 and sPLA2 can be considered as early predictors of aggravation of COVID-19 infections.

The review presents the data on clinical diagnostic value of studying one of the components of urinary proteome - macrophage chemotactic protein -1 (MCP-1). Along with the general characteristics of MCP-1, there are given the data on changes in its concentration regarding various diseases of the urinary system. It was shown that for various diseases and research conditions, the concentration of MCP-1 can be an important diagnostic criterion in assessing inflammatory, metabolic, fibrotic and other renal lesions.

Assessment of viral load levels in various biological samples taken from the respiratory tract can be an indicator of an ongoing process of active viral replication and may be used to monitor severe respiratory viral infections. The study of the relationship between SARS-CoV-2 viral load and immunological laboratory parameters is an important step in the search for clinical markers of COVID-19.The aim of this research was to quantify viral load in patients with COVID-19 and to identify the relation-ship between viral load and changes in the parameters of the cellular component of the immune system.A laboratory examination was carried out on 74 patients diagnosed with COVID-19, they were divided into 3 groups based on the severity of the disease: mild, moderate, severe. Total viral load in clinical samples was determined by the number of SARS-CoV-2 RNA copies per 100 copies of the reference RNaseP gene.     A comprehensive assessment of the cellular component of the immune system was performed using flow cytometry and direct monoclonal antibodies, and the IL-6, and C-reactive protein concentrations were determined.We revealed a relationship between the development of serious clinical conditions in the patients with COVID-19, and the levels of viral load. High levels of viral RNA in biological samples correlate with main indicators of the T cell component of the immune system associated with disease severity. In a subgroup of patients with an extremely high viral load, strong positive correlations were found between the relative numbers of cytotoxic lymphocytes (CD3+CD8+), activated T lymphocytes (CD3+HLA-DR+), as well as absolute and relative numbers of activated B lymphocytes and NK cells (CD3-CD25+).Laboratory monitoring of the cellular component of the immune system, along with the assessment of viral loads, should improve  early assessment of clinical condition in the patients with COVID-19. Changes   in expression levels of activation markers on immune cells can be potentially viewed as indicators of recovery during COVID-19.

To date, there is no consensus explaining the relationship between varying concentrations of IFNγ and the severity of infection caused by SARS-CoV-2. The aim of this article was to analyze and formulate conclusions from the selected studies and publications, which, in sum, provide a potentially reasonable view on the role of IFNγ in COVID-19 pathogenesis. This article highlights current data on the immunological role of IFNγ which affects differentiation of naive T helper cells, acting as a polarizing factor. It activates the major histocompatibility complex (MHC) class I and II, by increasing the expression of MHC I/II subunits, inhibiting replication of the viral particles by initiating activation of interferon-stimulated genes followed by subsequent synthesis of antiviral proteins. Moreover, IFNγ activates the production of cytokines by T cells, enhancing cytotoxic activity of the T killers. IFNγ exerts immunostimulatory and immunomodulatory effects via STAT1, SOCS1 and PIAS genes, thus regulating activation of the JAK-STAT signaling pathway. A number of studies were considered where the patterns of changes in serum IFNγ concentration were examined in viral infections and SARS-CoV-2. We performed a systemic analysis of the results of studies that showed a relationship between high concentrations of IFNγ and COVID-19 severity. In a number of studies, the significantly high levels of IFNγ in COVID-19 patients were often associated with a poor outcome of the disease. The median values of the IFNγ concentration in severe COVID-19 were found to be significantly higher compared to the results obtained in the cases of moderate severity. It shows an increase, in parallel with viral load in the nasopharyngeal samples upon worsening of the clinical condition. Based on the data on the decreased IFNγ concentrations in convalescent patients, the mechanism of antagonism between IFNγ and IL-4 is considered, where the decreases serum concentrations of IFNγ along with increasing level of IL-4 may be an indirect proof of normal adaptive immune response with subsequent development of antibodies to SARS-CoV-2 and gradual elimination of the virus from the body. Moreover, the evidence is discussed that the patients harboring some parasitic infections (Toxoplasma gondii, Cryptosporidium, Blastocystis hominis, Giardia duodenalis, Entamoeba histolytica) with persistently elevated level of IFNγ are at reduced risk for severe course of COVID-19.

Dangerous professions are associated with working conditions in which work factors cause a threat to the life of an employee and a high risk of injury. Employees of law enforcement agencies (the armed forces, law enforcement agencies, emergency staffs) are included in the list of dangerous professions. Their work is associated with the presence of a threat to life and health, psychological and physical overstrain, fatigue, suddenness of events with a shortage of time, information overload, etc. Their adaptive mechanisms are often distorted. Among them, one of the most vulnerable is the endocrine system. The aim is to study the hormonal supply of the body with the pituitary – thyroid gland system in persons of dangerous professions (law enforcement officers) at various levels of professional strain. Materials and methods: in different groups of law enforcement officers (combatants, regular policemen, cadets), a study was conducted to identify the features of thyroid hormone status (thyroid-stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) were determined). The results of the study: the analysis of the results showed the presence of statistically significant differences in most of the studied indicators between the study groups. In the group of combatants, the average level of TSH and T3 is higher compared to other participants in the study. Thus, the dependence of the secretory function of the pituitary-thyroid link of endocrine regulation on the nature of service and the degree of professional load is statistically proved. It is concluded that the identified features of the thyroid secretory function in law enforcement officers are an adaptive response to various requirements during the performance of professional duties. It is assumed that with prolonged exposure to stress factors, prolonged hormonal stress, dysfunctions of their regulation are possible, leading to disruption of interhormonal interactions, probable disruption of the adaptation process and maintenance of homeostasis in general.

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