Microvesicles produced by natural killer cells of the NK-92 cell line affect the phenotype and functions of endothelial cells of the EA.Hy926 cell line
Microvesicles (MVs) are small (100-1000 nm) subcellular structures produced by both motionless and activated cells that can transfer molecules to target cells, and regulate physiological and pathological processes. MVs of leukocyte origin, in particular those produced by natural killer cells (NK cells), remain the least studied population of MVs. NK cells can change the functional activity of endothelial cells (ECs) and are involved in regulating angiogenesis. The ability of NK cell-derived MVs to influence the functionality of ECs is understudied currently. We aimed to study the effect of MVs produced by NK cells of the NK-92 cell line on the phenotype, caspase activity, proliferation and migration of ECs of the EA.Hy926 cell line. We cultured ECs in the presence of MVs derived from the NK-92 cell line, and then used flow cytometry to assess changes in EC phenotype, intracellular protein transfer from MVs to ECs, and the relative death of ECs. We used western blot analysis to evaluate the expression of granzyme B in NK cells and in the MVs that they produced, as well as the expression of granzyme B, caspases, extracellular-regulated kinase (ERK) and protein kinase B (AKT) in ECs. We also assessed the proliferation and migration of ECs in the presence of MVs derived from cells of the NK-92 cell line. The results revealed significant differences in the proteomic profiles of cells of the NK-92 cell line and their MV product. Contact between ECs and MVs derived from cells of the NK-92 cell line is accompanied by the following events: a) expression of granzyme B in ECs, b) activation of caspase-9 and caspase-3, with partial EC death, c) appearance of the panleukocyte marker CD45 on ECs, d) decrease in CD105 expression, and increase in CD34 and CD54 expression, and e) inhibition of EC migration. Transfer of ERK (but not AKT) from MVs derived from cells of the NK-92 cell line to ECs, at a concentration 10 times lower than that which causes EC death, leads to an increase in EC proliferation
