Invitroexperimental rewiring of 4 neutrophilic granulocyte subsets from the pro-inflammatory to the anti-inflammatory phenotype in children with surgical purulent infection of soft tissue [ЭКСПЕРИМЕНТАЛЬНАЯ ПЕРЕОРИЕНТАЦИЯ INVITRO ФЕНОТИПА 4 СУБПОПУЛЯЦИЙ НЕЙТРОФИЛЬНЫХ ГРАНУЛОЦИТОВ ИЗ ПРОВОСПАЛИТЕЛЬНОГО К ПРОТИВОСПАЛИТЕЛЬНОМУ У ДЕТЕЙ С ХИРУРГИЧЕСКОЙ ГНОЙНОЙ ИНФЕКЦИЕЙ МЯГКИХ ТКАНЕЙ]

Treatment of young children with atypical or recurrent purulent soft tissue infections (PSTD) that do not respond well to surgery and antibiotics is most challenging. PSTD occurs against the background of impaired functioning of the immune system and, first of all, the system of neutrophilic granulocytes (NG). The vector effect of immunotropic therapy on a specific NG subsets may allow the correction of NG dysfunctions without compromising host protection, including strategies to enhance, inhibit or restore their functions. The aim of study: to evaluate in vitro the modulating effects of arginyl-alpha-aspartyl-lysyl-valyl-tyrosyl-arginine (HP) on the transformed phenotype of 4 NG subsets, as well as on the functional activity of NG in children with purulent-inflammatory soft tissue diseases. We studied samples of peripheral blood (PB) from young children 2-4 years old: 17 children with atypical acute PSTD and 10 apparently healthy children. At stage I, a comparative assessment of the content and phenotype of 4 NG subsets CD16+CD62L+СD63-, CD16+CD62L+СD63+, СD64-CD16+CD32+CD11b+, СD64+CD16+CD32+CD11b+, phagocytic and microbicidal functions of NG was carried out. At stage II, the in vitro system determined the effects of HP on NG in children with PSTD according to the studied parameters. By the method of flow cytometry (FC500 “Beckman Coulter” (USA), conjugates of MkAT “Beckman Coulter International S.A.” (France)), the relative number of NGs of the studied subsets and the density of receptor expression (MFI) were determined. To assess the phagocytic function of NG a microbiological method was used to assess the completeness of phagocytosis with S. aureus (strain 209). The activity of NG NADPH oxidase was investigated in the NBT-spontaneous test (NBTsp.) and in the in vitro NBT-induced test (NBTind.). A comparative study of PB samples from conventionally healthy children and children with PSTD made it possible to identify various variants of transformation of the phenotype of the studied NG subsets, associated with defects in their functional activity. In the in vitro system the effects of HP were demonstrated, manifested by a decrease in the amount of CD16+CD62L+CD63+NG and an increase in CD16+CD62L+CD63-NG, modulation of the negatively altered phenotype of subsets CD64-CD32+CD16+CD11b+NG and CD64+CD32+CD16+CD11b+NG, aimed at restoring phagocytic function and maintaining the tension of NADPH oxidases. As a result of the study it was found the immunomodulatory effects of HP, which is manifested in the reorientation of NG from the pro-inflammatory phenotype to the anti-inflammatory one, which can be used in the future when creating personalized targeted immunotherapy aimed at correcting defective functioning NG in early children, suffering from PSTD. © 2021 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved.