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Each stage of angiogenesis depends on the nature of the communication between endothelial cells and the microenvironment, and on the complex balance between stimulators and inhibitors of this process. Natural killer cells secrete a variety of cytokines and chemokines that can influence the microenvironment. The aim of this study was to assess the effect of protein fractions of an NK-92 natural killer cell lysate on the phenotype, proliferation and migration of the EA.hy926 endothelial cell line in an in vitro experimental model. We have shown that CD54 (ICAM-1) receptor expression by EA.hy926 cells after co-cultivation with 10–50 kDa and 30–80 kDa fractions was elevated in comparison with non-activated cells. The relative number of EA.hy926 cells with the CD54+ phenotype also increased after co-cultivation with the above fractions. The other remaining fractions (<20 kDa) had no effect on the expression of CD54, CD34, CD119 (IFNγR1) and CD31 (PECAM-1) receptors and the relative number of EA.hy926 cells. Proliferation and migration of EA.hy926 cells after co-cultivation with the fractions altered in opposite directions and concentration-dependently or remained unchanged. The residual area not occupied by migrated EA.hy926 cells after co-cultivation with the fractions did not always correlate with the intensity of migration and was not inversely proportional to the number of the migrated cells. Light fractions (<10 kDa) had no effect on the proliferation and migration of EA.hy926 cells. Using the MALDI-TOF mass spectrometric analysis, more than 1200 entries of proteins with a variety of functions were identified in the NK-92 natural killer cell lysate. Among those linked to natural killer cell functions are proteins related to signal transduction, cell skeleton, cell metabolism, cell proliferation/adhesion, immune response, and enzymes. Chemokines, cytokines, growth factors, semaphorins, defensins, collectin, ficolin, galectin-3, interferon β, TGFβ, VEGF, TNF ligands, and regulators of apoptosis could be specific agents responsible for the effects of the protein fractions seen on the target cells. These findings may indicate an alternative involvement of natural killer cell effector proteins in their communication with endothelial cells. The model used may also reflect the effect of the intracellular content of natural killer cells on the endothelium in case of their death by necrosis. [ABSTRACT FROM AUTHOR]

We analyzed the effect of individual cytokines that are secretory products of placenta typical of the uteroplacental bed. The proinflammatory cytokines IL-6, IFNγ, and IL-1β increased the expression of TGFβR2 molecule by trophoblast cells, while VEGF and PLGF increased the expression of CD45, CD29, and CD54 adhesion molecule by trophoblast cells. The antiinflammatory cytokine IL-4 increased LeptinR expression by trophoblast cells. PMA and TNFα also enhanced the adhesion of NK cells to trophoblast cells. Our findings suggest that NK cells involved CD11a, CD11b, and CD18 molecules during their transmigration through trophoblast, as well as during their transendothelial migration. [ABSTRACT FROM AUTHOR]

Studies of interactions between natural killer (NK) cells and trophoblasts and identification of conditions for the NK cells to perform their cytotoxic function are of fundamental and practical importance for understanding their role in the development of pathological processes and complications during pregnancy. In this study, we examined changes in the content of caspases and studied activation of these enzymes in Jeg-3 trophoblasts in various models of their coculturing with NK-92 cells and demonstrated the necessity of direct contact between these cell populations for the activation of caspase-8 and caspase-3 in the trophoblasts. Contact coculturing of the two cell lines resulted in the appearance of the cytotoxic protein granzyme B in Jeg-3 cells that was accompanied by a decrease in the content of this enzyme in NK-92 cells. Distant coculturing of NK-92 and Jeg-3 cells did not trigger initiator and effector caspases characteristic for the apoptosis development in Jeg-3 cells. The observed decrease in the content of procaspases in the trophoblasts may be associated with alternative non-apoptotic functions of these enzymes. [ABSTRACT FROM AUTHOR]

We evaluated cytotoxic activity of peripheral blood NK cells towards trophoblast cells. NK cells either isolated or in the composition of mononuclear cell fraction, caused death of trophoblast cells. In women with physiological pregnancy, the cytotoxic effect of NK cells present in mononuclear cell fraction preincubated with IL-2 was lower than in nonpregnant women, who had never been pregnant previously, and in fertile women. Cytotoxic activity of isolated NK cells preincubated with IL-2 in fertile women was lower than in nonpregnant women, who had never been pregnant previously. [ABSTRACT FROM AUTHOR]

We studied changes in angiogenesis during contact interaction of natural killer cells and endothelial cells in the presence of secretory products of trophoblast cells activated by various cytokines. Activated trophoblast regulates angiogenesis by producing soluble factors that affect endothelial cells either directly or indirectly through activation of proangiogenic activity of natural killer cells. A stimulating effect of the trophoblast supernatants activated by IL-1β and an inhibitory effect of trophoblast supernatants activated by IL-6 and TGFβ for the formation of tube-like structures by endothelial cells were revealed. During contact culturing, natural killer cells increased the length of tube-like structures formed by endothelial cells. The trophoblast activated by IL-1β affects angiogenesis both directly through the production of proangiogenic factors and indirectly through activation of the proangiogenic potential of natural killer cells. Trophoblast activated by IFNγ affects angiogenesis only by stimulating the proangiogenic potential of natural killer cells. Under conditions of contact interaction of natural killer cells and endothelial cells, soluble factors of trophoblast activated by IL-6 or TGFβ attenuated the angiogenesis-stimulating effect of natural killer cells. [ABSTRACT FROM AUTHOR]

NK cells present in different organs differ by their functional characteristics, in particular, proliferative activity. For studying tissue-resident NK cells, tissue-specific microenvironment should be reproduced. In case of decidual NK cells, this microenvironment is created by trophoblast cells. We developed a method for evaluation of proliferative activity of peripheral blood NK cells in the presence of trophoblast cells. Proliferative activity of peripheral blood NK cells was evaluated by the expression of protein Ki-67 after culturing with JEG-3 trophoblast cells. This method allows evaluating the functional state of NK cells in microenvironment specific for the decidua. [ABSTRACT FROM AUTHOR]