Novel approaches to increase resistance to acute respiratory infections

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Relevance . Respiratory infections are the most common in the world. In order to prevent epidemics, there is a need to improve the strategies for organizing medical care and develop new approaches in order to increase the nonspecific resistance, mobilize innate immunity. Objective . The aim of this study was to investigate the effect of glucosaminylmuramyldipeptide (GMDP) on the level of expression of markers of differentiation and activation of functionally significant subpopulations of dendritic cells in peripheral blood mononuclear cells of healthy donors,the second aim was to assess the effectiveness of GMDP in the prevention of acute respiratory infections in an unfavorable epidemiological period of the COVID-19 pandemic. Materials and Methods . An open comparative study included 309 apparently healthy participants, aged 19-22 years. At the first stage of the study, 42 participants (22 female and 20 male) took the drug Licopid 1 mg for 10 days according to the instructions, 1 tablet 3 times a day in order to prevent acute respiratory infections. Peripheral blood sampling was performed before taking the drug (day 0) and the next day after the last dose of the drug (day 12). Evaluation of the expression of markers of differentiation and activation of dendritic cell subpopulations HLA-DR, CD11c, CD123, CD80, CD83, CCR7, CD3, CD14, CD20 was assessed by flow cytometry. At the same time, mRNA was isolated from mononuclear cells of perfusion blood and, after reverse transcription, the level of gene expression was determined by RT PCR. At the next stage, the effectiveness of the prophylactic use of the drug Licopid in 267 students of the Institute of Physical Culture was assessed in order to prevent acute respiratory infections in an unfavorable epidemiological period; the observation period was 12 months. Results and Discussion . A study of the relative quantitative composition of DCs in the peripheral blood of healthy donors by flow cytometry revealed the possibility of an increase in their total number, as well as subpopulations of MDC and PDC under the influence of GMDP. There was a statistically significant increase in the receptors for the chemokine CCR7, which is responsible for the recruitment of DCs to the secondary lymphoid organs. Analysis of the levels of expression of genes XCR1, CD11b , and CD103 showed a statistically significant effect of GMDP on an increase in their expression compared to the baseline level (before GMDP intake), with the mean value being higher in participants undergoing moderate exercise. It was found that the use of the drug Licopid 1mg for the purpose of preventing and reducing the seasonal incidence of acute respiratory infections at the stage of basic training of students of the Institute of Physical Culture contributed to a decrease in the incidence of acute respiratory infections within 12 months of observation after taking the drug. The number of episodes of acute respiratory infections decreased 3.7 times, while the group with 3 or more episodes of acute respiratory infections during the year, which constituted 14.5 % of participants, completely disappeared. The maximum efficiency of GMDP was observed in the track and field command, in which the number of participants who had no episodes of acute respiratory infections during the year increased by 7 times. Conclusion . Our data complement the modern understanding of the molecular mechanism of action of GMDP and substantiate the possibility of its experimental and clinical use in order to develop new strategies for organizing medical care in order to increase the nonspecific resistance of the organism.