ABSTRACT
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 relationship 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.Copyright © Nikitin Yu.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.
ABSTRACT
Current review presents a brief overview of the immune system dysregulation during acute COVID-19 and illustrates the main alterations in peripheral blood CD4+ T-cell (Th) subsets as well as related target cells. Effects of dendritic cell dysfunction induced by SARS-CoV-2 exhibited decreased expression of cell-surface HLA-DR, CCR7 as well as co-stimulatory molecules CD80 and CD86, suggesting reduced antigen presentation, migratory and activation capacities of peripheral blood dendritic cells. SARS-CoV-2-specific Th cells could be detected as early as days 2-4 post-symptom onset, whereas the prolonged lack of SARS-CoV-2-specific Th cells was associated with severe and/or poor COVID-19 outcome. Firstly, in acute COVID-19 the frequency of Th1 cell was comparable with control levels, but several studies have reported about upregulated inhibitory immune checkpoint receptors and exhaustion-associated molecules (TIM3, PD-1, BTLA, TIGIT etc.) on circulating CD8+ T-cells and NK-cells, whereas the macrophage count was increased in bronchoalveolar lavage (BAL) samples. Next, type 2 immune responses are mediated mainly by Th2 cells, and several studies have revealed a skewing towards dominance of Th2 cell subset in peripheral blood samples from patients with acute COVID-19. Furthermore, the decrease of circulating main Th2 target cells - basophiles and eosinophils - were associated with severe COVID-19, whereas the lung tissue was enriched with mast cells and relevant mediators released during degranulation. Moreover, the frequency of peripheral blood Th17 cells was closely linked to COVID-19 severity, so that low level of Th17 cells was observed in patients with severe COVID-19, but in BAL the relative number of Th17 cells as well as the concentrations of relevant effector cytokines were dramatically increased. It was shown that severe COVID-19 patients vs. healthy control had higher relative numbers of neutrophils if compared, and the majority of patients with COVID-19 had increased frequency and absolute number of immature neutrophils with altered ROS production. Finally, the frequency of Tfh cells was decreased during acute COVID-19 infection. Elevated count of activated Tfh were found as well as the alterations in Tfh cell subsets characterized by decreased "regulatory" Tfh1 cell and increased "pro-inflammatory" Tfh2 as well as Tfh17 cell subsets were revealed. Descriptions of peripheral blood B cells during an acute SARS-CoV-2 infection werev reported as relative B cell lymphopenia with decreased frequency of "naive" and memory B cell subsets, as well as increased level of CD27hiCD38hiCD24- plasma cell precursors and atypical CD21low B cells. Thus, the emerging evidence suggests that functional alterations occur in all Th cell subsets being linked with loss-of-functions of main Th cell subsets target cells. Furthermore, recovered individuals could suffer from long-term immune dysregulation and other persistent symptoms lasting for many months even after SARS-CoV-2 elimination, a condition referred to as post-acute COVID-19 syndrome.Copyright © 2022 Saint Petersburg Pasteur Institute. All rights reserved.
ABSTRACT
In the context of the COVID-19 pandemic, scientific interest is growing in studying the impact of the proposed vaccination on women's reproductive health. As is known, alterations in the state of the immune system and activation of an autoimmune response can lead to reproductive failure in women and potential complications of subsequent pregnancy. Objective(s): to evaluate the effect of the "Gam-COVID-Vac" on the immune status parameters, the relationship of their changes and the specific immune response to vaccination with the dynamics of the level of autoantibodies in women of reproductive age. The prospective study included 120 women who were vaccinated against COVID-19 with the "Gam-COVID-Vac". The criteria for inclusion in the study were: the age from 18 to 49 years, the absence of COVID-19 in the anamnesis, a negative result of a study on SARS-CoV-2 by PCR and negative results of tests for antibodies of classes G and M to SARS-CoV-2 before vaccination, the absence of pregnancy and serious somatic diseases. The patients were examined twice: immediately before vaccination and 90-100 days after the introduction of the 1st component of the vaccine. The level of IgG antibodies to SARS-CoV-2 after vaccination was assessed using ELISA. Before and after vaccination, the levels of antiphospholipid, anti-nuclear, organ-specific and antihormonal autoantibodies were determined, peripheral blood lymphocytes were immunophenotyped to determine the main subpopulations (CD3, CD4, CD8, CD19, CD5, CD16, CD56), as well as the expression of activation markers of lymphocytes (HLA-DR, CD25, CD147) using monoclonal antibodies. The effectiveness and safety of the combined vector vaccine against COVID-19 were high. Specific IgG antibodies to SARS-CoV-2 were produced in 98.3% of vaccinated women, no serious adverse reactions were observed. After vaccination, there was an increase in the level of some autoantibodies within the reference ranges, only IgM antibodies to phosphatidylethanolamine (PE) and IgG antibodies to DNA increased above the reference values. However, this increase was transient. After vaccination, the following changes in the parameters of the immunogram were observed: an increase in the content of cells with CD3+CD25+, CD19+ phenotype in peripheral blood and a decrease in the content of cells with CD56+CD16+ phenotype within the reference ranges, a decrease in CD147+/CD3+. Weak correlations were noted between these changes in immunogram parameters and the levels of some autoantibodies. The specific antiviral immune response to vaccination did not correlate with the autoimmune response. Vaccination with "Gam-COVID-Vac" is effective and safe and does not lead to disorders in the immune system. The observed increase in the level of autoantibodies to PE and DNA is transient. Changes in the parameters of the immune status within the reference ranges may be due to vaccination and the development of a specific antiviral immune response. Copyright © 2022, SPb RAACI.