In vitro effects of hexapeptide -arginyl- alpha- aspartyl- lysyl- valyl- tyrosyl- arginine on 2 subsets and functions of neutrophilic granulocytes in moderate COVID-19

ABSTRACT

Background: The hyperactivated subsets of neutrophilic granulocytes (NG) play a negative role on the development, course and outcome of the COVID-19. With this position, NG are interesting target for creation of new therapeutic approaches. Method(s) The study group (SG) included 31 patients with moderate COVID-19, aged 61(57;71)years. Before and after incubation of whole blood with HP (106 g/l, 60 min., 37degreeC) 2 NG subsets were tested major -CD64- CD16+CD32+CD11b+, minor -CD64+ CD16+CD32+CD11b+ with detection of their phenotypes using MFI (FC 500, Beckman Coulter, USA). Phagocytic activity of NG against S. aureus was studied. Comparison group(CG) consisted 22 healthy volunteers 58 (57;70) years old. Result(s) In patients with COVID-19 the minor subset of NG CD64+CD16+CD32+CD11b+(% ) was significantly increased in 5-fold versus the CG (p <= 0.005) and had transformed phenotype CD64dimCD16brightCD32midCD11bbright versus CD64midCD16dimCD32midCD11b brightin the CG (p <= 0.005). This transformed phenotype had high expression levels of receptors of activation CD16 and CD11b, that suggested its negative hyperactivation. The % of the major subset NG did not change (p > 0.05), but an altered phenotype of CD64-CD16brightCD32midCD11bdimNG was determine against CD64-CD16dimCD32midCD11boNG in the CG. Defects of phagocytic activities of NG were found the decrease of % an active phagocytic NG, absorbing and digesting abilities (p1 <= 0.005;p2 <= 0.005;p3 <= 0.005).The effects of HP in vitro were shown the significant decreasing of NG minor subset (%) in comparison with it's level before HP influences (p <= 0.005) reached to the values of the CG (p > 0.05). In parallel, the phenotype of minor subset changed to CD64brightCD16dimCD32midCD11bo, with decreasing level of CD16 to normal (p > 0.05). The transformed phenotype of the major subset was changed to CD64-CD16midCD32brightCD11 bmidNG a decrease in MFI CD16, an increase in MFI CD32 and MFI CD11b (p1 <= 0.005;p2 <= 0.005;p3 <= 0.005). The restoration of defective phagocytic function of NG was received. Conclusion(s) Immunomodulating effects of HP in vitro on NG in moderate COVID-19 were shown positive remodeling of the phenotype of minor aggressive NG subset from hyperactivated to normal and the restoration of defective NG phagocytic function.