Pleiotropic immunomodulating effects of peptide Arginyl-alpha-Aspartyl-Lysyl-Valyl-Tyrosyl-Arginine on various subsets of neutrophilic granulocytes and their phenotype in patients with COVID-19 in vitro

The key role of neutrophilic granulocytes (NG) in the pathogenesis of COVID-19 makes them new targets for therapeutic approaches and of influencing the course and outcome of the disease, restoring changes in the phenotype and functions of NG. Synthetic peptides or polypeptide complexes of action are the most promising in the treatment of COVID-19. Aim: to reveal the effects of the influence of the hexapeptide (HP) – Arginyl-alpha-Aspartyl-Lysyl-Valyl-Tyrosyl-Arginine on the phenotype of functionally significant NG subsets in moderate COVID-19.The study examined patients 61 (57-71) years old (n = 45) in the acute period of COVID-19 – study group1 (SG1). In vitro, samples SG1 were incubated with HP (106 g/L, 60 min, 37 °C) – study group2 (SG2). The number of NG subsets was evaluated: CD16+IFNα/βR1+CD119+, CD16+IFNα/βR1+CD119- , CD16+IFNα/βR1+CD119+, CD64- CD16+CD32+CD11b+, CD64+CD16+CD32+CD11b+ and phenotype by membrane receptor expression density (MFI) (FC 500, Beckman Coulter, USA); NG phagocytic activity was tested before and after incubation with HP. The comparison group (GS) – of 22 volunteers examined in the pre-COVID period.It was revealed that unidirectional effects of HP in vitro contributing to the restoration of the phenotype of subsets CD16+IFNα/βR1- CD119+, CD16+IFNα/βR1+CD119- to CG indicators. There was a decrease in MFI CD16 (p < 0.05) in both subsets; MFI CD119 (p < 0.05) in the CD16+IFNα/βR1- CD119+NG subset, MFI IFNa/βR1 in the CD16+IFNα/βR1+CD119- NG subset. The effects of HP on the phenotype of CD16+IFNα/βR1+CD119+NG subsets in 76% of cases were manifested by a decrease in MFI CD16 (p<0.05), an increase in MFI IFNα/βR1 and CD119 (p1, 2<0.05), and in 24% of cases a decrease in MFI IFNα/βR1 (p<0.05). HP in vitro remodeling of the phenotypes subsets CD64- CD16+CD32+CD11b+ and CD64+CD16+CD32+CD11b+ were established, providing the usefulness of effector functions from hyperactivated to normal. In the CD64- CD16+CD32+CD11b+ subset, there was a decrease in MFI CD16 and CD11b to the indicators CG (p1, 2 < 0.05). Recovery of the NG phenotype under the influence of HP led to the restoration of the phagocytic function of NG.Positive effects of HP in vitro on the phenotypes of subsets actively and NGfunctions in COVID-19 open up prospects for the creation of new methods of immunotherapy to restore NG dysfunctions.