Background: Endometriosis is a complex condition that impairs women's quality of life and reproductive potential. Its diagnosis remains significant challenge for clinicians. The aim of the study was to investigate cancer-like immune evasion mechanisms in endometriosis and to develop a novel diagnostic model using machine learning. Methods: In this study, we measured the levels of soluble forms of the following immune markers in blood serum and peritoneal fluid (PF): sMICA, sMICB, sEng, sCD25, s4-1BB, sB7.2, sCTLA-4, sPD-L1, sPD-1, sTIM-3, sLAG-3, and sGal-9. Results: sMICB levels in PF differed across endometriosis stages and were higher in patients with endometriosis-associated adhesions. sMICA levels in PF were elevated in women with endometriosis-associated infertility. The disease severity was inversely correlated with serum sB7.2 levels and positively correlated with serum sTIM-3 levels. A logistic regression model achieved an accuracy = 0.79, AUC = 0.94, and F1-score = 0.88, whereas XGBoost performed better with accuracy = 0.94, AUC = 0.95, and F1-score = 0.96. The key predictive features in both models were sMICB serum level and patients' pain score. Conclusions: Our results demonstrate the potential role of sMICA and sMICB shedding in endometriosis and present a novel, minimally invasive diagnostic approach.

Natural killer (NK) cells are effector cells of the innate immune system. The cytokine microenvironment influences NK cell function. Dysregulation of NK cell cytotoxicity can manifest in reproductive disorders and is also observed in tumor-transformed tissues. The search for immunotherapies capable of regulating NK cell activity is therefore relevant. This study aimed to evaluate the effect of the TGFβ signaling pathway inhibitor and the cyclin-dependent kinase (CDK) 7/12/13 inhibitor on the transcriptional profile of NK-92 cell line. In the study, the cytokines TGFβ1, IL-12, IL-15, IL-18, and TNFα, and the TGFβ receptor type 1 (TGFβR1) inhibitor LY3200882 and the CDK7/12/13 inhibitor THZ1 were used. The cells were cultured sequentially in the presence of inhibitors and cytokines, followed by assessment of the gene expression of NCR2, NCR3, AHR, NCAM1, B3GAT1, EOMES, GATA3, KLRC1, KLRC2, CCL5, IL10 and TBX21. We observed direct effects of the inhibitors on NK cells. LY3200882 increased the expression of KLRC1 and B3GAT1, and reduced NCAM1. THZ1 increased the expression of KLRC1, KLRC2, AHR and EOMES, while it reduced IL-10 and NCR2. IL-12, IL-15, IL-18, and TNFα modified the gene expression of some phenotypic and cytotoxic receptors and transcription factors. TGFβ1 increased the expression of KLRC1, NCAM1, and B3GAT1. Blocking TGFβ-dependent signaling with LY3200882 abolished TGFβ1 effects. We assessed CD56 presence on NK-92 cell membrane and found its increase in the presence of LY3200882. After LY3200882 treatment, in the presence of TGFβ1 and choriocarcinoma cell line JEG-3, the expression of CD56 receptor on NK cell membrane decreased. Pretreating NK cells with THZ1 decreased the expression of NCAM1, B3GAT1, and EOMES in the presence of TGFβ1. Thus, LY3200882 partially neutralized TGFβ1 effects on the expression of NK cell receptor genes. THZ1 followed by TGFβ1 treatment promoted NK cell transcriptional profile characteristic for CD56dim NK cells. Both LY3200882 and THZ1 affected the NK cell transcription even without cytokine treatment. The independent effects of synthetic inhibitors on NK cells, as well as their influence in the presence of tumor cells, should be considered.

Functions of natural killer cells (NK cells) can be modulated by environmental stimuli. However, the role of bacterial components in this modulation remains an area of ongoing research. This study investigates how bacterial supernatants influence NK cell function—including cytotoxicity, phenotype, and cytokine and mRNA production—following co-culture. These parameters were measured by flow cytometry and RT-PCR. We found that NK cells express TLR2 and TLR5, and that exposure to supernatants from ESKAPE group bacteria modified their cytotoxicity against JEG-3 and K-562 cell lines and their NKG2A and IL-10 mRNA levels. Our findings indicate that bacteria can modify NK cell features and their interactions with other cells in the microenvironment.

Placenta development is largely determined by the interaction of natural killer (NK) cells and trophoblast cells. Despite intensive research, the role of NK cells and methods for correcting their functional activity in reproduction remain controversial. The aim of this study was to investigate the effect of protein fractions of NK cell lysate on trophoblast cell proliferation in a model experiment in vitro. Chromatographic separation resulted in obtaining six cell lysate fractions with different sets of proteins (25–250 kDa). It was found that all the studied fractions stimulated trophoblast cell proliferation. Proliferation markers such as protein kinase B (AKT/PKB) and extracellular signal-regulated kinases (ERK1/2) were found in the protein fractions with molecular weights of 36–250, 29–66, and 47–62 kDa. The obtained data on the change in the proliferative activity of JEG-3 cells under the influence of the NK-92 cell lysate fractions hypothetically reflect the behavior of chorionic cells surrounded by NK cells in the event of their death under normal or pathological conditions caused by viral and bacterial infections, as well as other stress factors that lead to reproductive pathology.

The uterine decidua contains NK cells differing in their characteristics from classical NK cells, as well as other populations of innate lymphoid cells (ILCs). ILC differentiation depends on the active transcription factors: ILC1 is characterized by T-bet expression, ILC2 is defined by RORα and GATA3, ILC3 expresses RORγt and AhR. We analyzed in vitro the expression of transcription factors by NK cells in the presence of trophoblast cells and cytokines and changes in NK cell cytotoxic activity. We used NK-92 and JEG-3 cell lines, which we cocultured in the presence of IFNγ, IL-10, IL-15, and TGFβ. Then, cells were treated with antibodies to AhR, Eomes, GATA-3, RORα, RORγt, and T-bet and were analyzed. We determined NK cell cytotoxicity towards K562 cells. To characterize the functional state of trophoblast cells, we estimated their secretion of TGFβ and βhCG. We showed that in the presence of trophoblasts, the expression of the classical NK cell transcription factors—Eomes, T-bet, as well as RORα, regulating ILC2 differentiation, and AhR, participating in NCR+ ILC3 formation—decreased in NK cells. RORγt expression typical for NCR- ILC3 remained unchanged. IFNγ inhibited AhR expression. IL-10 stimulated an increase in the number of T-bet+ ILC1-like cells. Both IL-10 and IFNγ suppressed RORα expression by NK cells and stimulated TGFβ secretion by trophoblasts. After coculture with trophoblast cells, NK cells reduced their cytotoxicity. These results indicated trophoblast cell influence on the acquisition of ILC1 and ILC3 characteristics by NK cells.

MICA/B molecules (MICs) are stress-induced molecules expressed by infected and tumor cells. Their expression also characterizes trophoblast cells. Cytotoxic lymphocytes, including natural killer (NK) cells, express the NKG2D receptor, aiding them in the recognition and destruction of target cells that present MICs. To evade destruction, target cells employ various defense mechanisms, including the secretion of soluble forms of MICs. Choriocarcinoma JEG-3 cells and NK-92 cells were used to assess the expression of MICs and NKG2D. The cytotoxicity of NK-92 cells against JEG-3 cells in the presence of trichostatin A (TSA), anti-MICA/B antibodies (anti-MICA/B), and recombinant MIC proteins (rMICA/B) was evaluated. JEG-3 cells and NK-92 cells express MICs. Additionally, NK-92 cells exhibit high levels of NKG2D receptor expression. TSA treatment reduced the surface expression of MICs on choriocarcinoma cells, and was also associated with the release of soluble MICB. However, the TSA-induced decrease in MIC expression by choriocarcinoma cells did not protect them from the cytotoxic effects of NK cells. Only the activation of NK cells by IL-12 resulted in a decline in susceptibility of TSA-treated choriocarcinoma cells to NK cell-mediated cytotoxicity. Thus, NK cells activated by IL-12 lose their ability to effectively kill TSA-treated choriocarcinoma cells through the MIC-mediated mechanisms.

Natural killer (NK) cells are a population of innate immune cells that have cytotoxic functions and are involved in protecting the body from viruses and transformed cells. Placental development is largely determined by the interaction of decidual NK cells and trophoblast cells. During pregnancy, NK cells accumulate around trophoblast cells, while regulating trophoblast proliferation, migration and invasion through the secretion of cytokines and growth factors. The trophoblast, in turn, secretes chemokines and expresses ligands for NK cell adhesion receptors. Thus, functional regulation of trophoblast and NK cells is reciprocal. Despite intensive research, the role of NK cells and methods for correcting their functional activity in reproduction remain controversial. The aim of this study was to assess the effect of NK cell lysate protein fractions on the phenotype, migration and apoptosis of trophoblast cells in an in vitro model experiment, using a new methodological approach. Chromatographic separation yielded six fractions with different protein cargoes. It was found that CD105 (endoglin) expression on the surface of JEG-3 trophoblast cells after their cultivation in the presence of high- (< 250 kDa) or low-molecular-weight (< 45 kDa) fractions of NK-92 whole-cell lysate was reduced compared to spontaneous expression, with the relative count of trophoblast cells with a CD105+ phenotype being also lowered. In addition, one of the low-molecular-weight fractions decreased TRAIL-R2 receptor expression by trophoblast cells. The high-molecular-weight fractions did not enable trophoblast cells to migrate completely through a semi-permeable membrane, with the area occupied by the migrated cells not exceeding the baseline control area. Moreover, the high-molecular-weight fraction containing the TGFβ dimer increased p-SMAD2/3 level in trophoblast cells 1 h after co-culture, followed by a decrease in the level of this phosphorylated form after 2 or more hours, and also elevated procaspase-3 level one day after co-culture. The data obtained hypothetically reflect the possible behavior of chorion cells under the influence of collapsing NK cells in the event of their death under both normal and pathological conditions caused by viral and bacterial infections, as well as other stress factors leading to reproductive pathology.

The interaction of natural killer and trophoblast cells underlies maternal-fetal immune tolerance. The data on the participation of endoglin (ENG, CD105), or its soluble form, in the regulation of the communication of these cells are currently insufficient. In this study, we have investigated the role of endoglin in the intercellular interactions between natural killer cells and trophoblasts. Here, we show that NK-92 cells and JEG-3 cells constitutively express MICA/B, and CD105. In the presence of JEG-3 cells, the expression of NKG2D, CD94, MICA/B, and CD105 by NK-92 cells was increased, and the number of NK-92 cells expressing NKG2A, CD94, and MICA was reduced. Antibodies against ENG and recombinant endoglin (rENG), attenuated the trophoblasts’ influence and returned the phenotype of the NK-92 cells to that of cells found in monoculture conditions. The antibodies and rENG also increased the expression of pSMAD2/3 by NK cells in both monoculture and co-culture conditions. The antibodies increased the trophoblasts’ sensitivity to the cytotoxic effect of NK cells. In general, our findings indicate a significant role of endoglin in the intercellular communication between NK cells and trophoblasts. We also speculate that endoglin forms a complex with TGFβ, which aids in TGFβ trafficking between these cells.

Communication between natural killer cells (NK cells) and monocytes/macrophages may play an important role in immunomodulation and regulation of inflammatory processes. The aim of this research was to investigate the impact of NK cell-derived large extracellular vesicles on monocyte function because this field is understudied. We studied how NK-cell derived large extracellular vesicles impact on THP-1 cells characteristics after coculturing: phenotype, functions were observed with flow cytometry. In this study, we demonstrated the ability of large extracellular vesicles produced by NK cells to integrate into the membranes of THP-1 cells and influence the viability, phenotype, and functional characteristics of the cells. The results obtained demonstrate the ability of large extracellular vesicles to act as an additional component in the immunomodulatory activity of NK cells in relation to monocytes.

Natural killer cells (NK cells) exert cytotoxicity towards target cells in several ways, including the expression of apoptosis-mediating ligands (TRAIL, FasL). In addition, NK cells themselves may be susceptible to apoptosis due to the expression of TRAIL receptors. These receptors include TRAIL-R1 (DR4), TRAIL-R2 (DR5), capable of inducing apoptosis, and TRAIL-R3 (DcR1), TRAIL-R4 (DcR2), the so-called “decoy receptors”, which lack an intracellular domain initiating activation of caspases. Of particular interest is the interaction of uterine NK cells with cells of fetal origin, trophoblasts, which are potential targets for natural killer cells to carry out cytotoxicity. The aim of this work was to evaluate the expression of proapoptotic receptors and their ligands as well as CD107a expression by NK cells in a model of interaction with trophoblast cells. To evaluate NK cells, we used cells of the NK-92 line; cells of the JEG-3 line were used as target cells. The cytokines IL-1β, IL-15, IL-18, TNFα, IL-10, TGFβ and conditioned media (CM) of the first and third trimester chorionic villi explants were used as inducers. We established that cytokines changed the expression of apoptotic receptors by NK cells: in the presence of TNFα, the amount and intensity of Fas expression increased, while in the presence of TGFβ, the amount and intensity of expression of the DR5 receptor decreased. Soluble chorionic villi factors alter the expression of TRAIL and FasL by NK-92 cells, which can reflect the suppression of the TRAIL-dependent mechanism of apoptosis in the first trimester and stimulating the Fas-dependent mechanism in the third trimester. In the presence of trophoblast cells, the expression of TRAIL and DcR1 by NK cells was reduced compared to intact cells, indicating an inhibitory effect of trophoblast cells on NK cell cytotoxicity. In the presence of chorionic villi CM and trophoblast cells, a reduced number of NK-92 cells expressing DR4 and DR5 was found. Therefore, soluble factors secreted by chorionic villi cells regulate the resistance of NK cells to death by binding TRAIL, likely maintaining their activity at a certain level in case of contact with trophoblast cells.

This review presents current data on the origin of monocytes/macrophages, the conditions necessary for the differentiation of monocytes into M1 or M2 macrophages. Three subpopulations of peripheral blood monocytes are described: (I) classical – the main subpopulation (85-90%), effectively carrying out phagocytosis; (II) intermediate monocytes (5-10%) – participate in antigen processing and presentation, in angiogenesis, vascular endothelium restoration; (III) non-classical monocytes (10%) - "patrol" vascular network, remove cellular debris, participate in tissue remodeling. The review provides detailed characteristics for each subclass of macrophages: pro-inflammatory (M1) and anti-inflammatory (M2), which play different roles in the initiation and resolution of inflammation; their phenotype, the spectrum of secreted cytokines, the expression of transcription factors, and the functions performed are described. For the M2 population, the features of the subpopulation are described in detail: M2a, M2b, M2c, M2d. The review presents methods and approaches to obtaining polarized macrophages in vitro from both peripheral blood monocytes and cells of transplanted cultures based on signals received by macrophages in vivo; the phenotype, cytokine production and functional properties of artificially polarized macrophages depending on the conditions of their production are given. The review examines in detail the features of contact and distant interaction of macrophages of various subclasses with microenvironment cells on the example of natural killer cells and trophoblast cells, provides information on changes in the phenotype, transcriptional and secretory profile of interacting cells. The mechanisms of trophoblast control of macrophage differentiation into a unique M2 population of decidual macrophages controlling both the development and functioning of the trophoblast and its apoptosis are described. The review examines in detail the currently known variants of the interaction of macrophage subpopulations with natural killers. The influence of Mf on NK cells manifests itself in a change in the expression of transcription factors by the latter, which determine not only their differentiation, but also their functional activity. Macrophages are considered as cells that actively influence the functional state and differentiation of natural killers. The review examines the mechanisms of the relationship of all three types of cells: macrophages, trophoblast and natural killers in the area of uteroplacental contact. The study of the interactions of these cells will shed light not only on the features of intercellular relationships in the area of uteroplacental contact, but also on the relationship of tumor cells with NK cells and macrophages.

BACKGROUND:In obstetrics and reproductive medicine, the use of intravenous immunoglobulin remains controversial. There are no clearly developed indications for immunoglobulins therapy. The search for immunological criteria for prescribing this therapy is an urgent task AIM:The aim of this study was to evaluate the effectiveness of the use of intravenous immunoglobulins in the complex therapy of women with multiple reproductive losses associated with changes in the quantitative and functional parameters of natural killer cells. MATERIALS AND METHODS:Group 1 consisted of 61 women with recurrent miscarriage; group 2 involved 40 women with two or morein vitrofertilization failures, while group 3 comprised 27 healthy fertile individuals. The activity of blood natural killer cells was assessed by CD107a expression before and after activation. Patients with altered natural killer cell activity received intravenous immunoglobulins therapy under the control of the dynamics of immunological parameters. RESULTS:The number of natural killer cells that expressed CD107a before and after activation differed between the study groups. In patients receiving intravenous immunoglobulins, gestational complications were observed less frequently, with the incidence of biochemical pregnancy being higher. CONCLUSIONS:In patients with early reproductive failures (such as recurrent miscarriage andin vitrofertilization failures) and immunological abnormalities in the form of altered Natural killer cell activity, the use of intravenous immunoglobulins has an immunomodulatory and clinical effect.

BACKGROUND: Alteration in the composition and function of endometrial immune cells, in particular NK cells, are associated with implantation and placentation pathology, which is considered as one of the causes of reproductive losses. However, data regarding abnormalities in the number and activity of NK cells in repeated implantation failures, including depending on the type of infertility, remain ambiguous. AIM: The aim of this study was to evaluate the number of CD56+ and CD16+ cells and the area of expression of CD107a and NKG2D markers in the endometrium of patients with repeated implantation failure (RIF). MATERIALS AND METHODS: This prospective comparative study included patients with RIF (main group I, n = 47), who were divided into two subgroups: Ia, patients with primary infertility (n = 29); Ib, patients with secondary infertility (n = 18). Comparison group II included patients with a history of effective ART programs (n = 17). Control group III included healthy fertile women without a history of reproductive loss (n = 12). Endometrial biopsies were obtained on days 19–23 of the menstrual cycle. The expression of CD56+, CD16+, CD107a and NKG2D was assessed by immunohistochemistry. RESULTS: In the endometrium of patients in groups I and II, as compared to the control group, the number of CD56+ cells was significantly increased (p 0.001). In patients of subgroup Ia, when compared to the control group, we verified an increase in the number of CD16+ cells (p 0.05) and a decrease in the expression of CD107a (p 0.05). In patients in groups I and II, a negative correlation was revealed between the number of CD56+ and CD16+ cells and the number of pregnancies in history (rs = –0.30 and rs = –0.34, p 0.05), while a positive correlation was found between the expressions of CD56+ and CD107a (rs = 0.66 and rs = 0.75, p 0.05). In patients in group II, a positive correlation was revealed between the expressions of CD16+ and CD107a (rs = 0.75, p 0.05). In the endometrial stroma, CD107a expression increased significantly in patients in group I (p 0.05), while NKG2D expression increased in groups II and III (p 0.01, p 0.05) from the early to the middle stage of the secretion phase. In patients of group II, a positive correlation was established between the expressions of CD56+ and NKG2D (rs = 0.68, p 0.05). CONCLUSIONS: In the endometrium of patients with primary infertility and RIF, the number of CD56+ and CD16+ cells is increased with a decrease in the expression of their activation marker CD107a, which may be a potential mechanism for impaired implantation. Further studies of the immune profile of the endometrium may help to personalize diagnostic and therapeutic approaches to management of patients with RIF and to increase the chances of pregnancy in ART programs.

Angiogenesis is the development of new blood vessels from pre-existing ones. It is a complex multifaceted process that is essential for the adequate functioning of human organisms. The investigation of angiogenesis is conducted using various methods. One of the most popular and most serviceable of these methods in vitro is the short-term culture of endothelial cells on Matrigel. However, a significant disadvantage of this method is the manual analysis of a large number of microphotographs. In this regard, it is necessary to develop a technique for automating the annotation of images of capillary-like structures. Despite the increasing use of deep learning in biomedical image analysis, as far as we know, there still has not been a study on the application of this method to angiogenesis images. To the best of our knowledge, this article demonstrates the first tool based on a convolutional Unet++ encoder–decoder architecture for the semantic segmentation of in vitro angiogenesis simulation images followed by the resulting mask postprocessing for data analysis by experts. The first annotated dataset in this field, AngioCells, is also being made publicly available. To create this dataset, participants were recruited into a markup group, an annotation protocol was developed, and an interparticipant agreement study was carried out.

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.

The interaction of natural killer (NK) and trophoblast cells underlies the formation of immune tolerance in the mother–fetus system and the maintenance of the physiological course of pregnancy. In addition, NK cells affect the function of trophoblast cells, interacting with them via the receptor apparatus and through the production of cytokines. Microvesicles (MVs) derived from NK cells are able to change the function of target cells. However, in the overall pattern of interactions between NK cells and trophoblasts, the possibility that both can transmit signals to each other via MVs has not been taken into account. Therefore, the aim of this study was to assess the effect of NK cell-derived MVs on the phenotype, proliferation, and migration of trophoblast cells and their expression of intracellular messengers. We carried out assays for the detection of content transferred from MV to trophoblasts. We found that NK cell-derived MVs did not affect the expression of CD54, CD105, CD126, CD130, CD181, CD119, and CD120a receptors in trophoblast cells or lead to the appearance of CD45 and CD56 receptors in the trophoblast membrane. Further, the MVs reduced the proliferation but increased the migration of trophoblasts with no changes to their viability. Incubation of trophoblast cells in the presence of MVs resulted in the activation of STAT3 via pSTAT3(Ser727) but not via pSTAT3(Tyr705). The treatment of trophoblasts with MVs did not result in the phosphorylation of STAT1 and ERK1/2. The obtained data indicate that NK cell-derived MVs influence the function of trophoblast cells, which is accompanied by the activation of STAT3 signaling.

Natural killer cells (NK cells) represent a group of lymphocytes of innate immunity. In addition to NK cells of peripheral blood, tissue-resident populations are described. NK cells of the decidual envelope (decidual NK cells) represent one of the local NK cell populations. Decidual NK cells differ in phenotype and function from peripheral blood NK cells. These cells have, mainly, regulatory functions. At the same time they retain the ability to perform cytotoxic effects. In the uterus, NK cells are located closely to the cells of fetal origin, i.e., trophoblast cells, which differentiate from the outer layer of the invading blastocyst. The purpose of the review article was to analyze the literature data on the studies of the molecular interactions between NK cells and trophoblast cells, as well as potential means of regulating these interactions. The review presents currently available data on receptor-mediated effects (due to adhesion molecules and cytotoxic receptors) and distant interactions (involving cytokines, chemokines and growth factors secreted by the both cell types) between NK population and trophoblast cells. The receptors regulating contacts of NK cells and trophoblast cells with extracellular matrix are also considered. The review provides information on activation of signaling pathways in NK cells and trophoblast cells resulting from their interaction with each other and components of the extracellular matrix. Currently, the molecular mechanisms regulating the NK cell functions and their interaction with trophoblast cells have not been studied sufficiently. The authors attempted to consider molecular regulation of the functional activity of NK cells mediated by the molecular complex of RNA polymerase II. We also describe participation of cyclin-dependent CDK8/19 kinases which comprise a part of the mediator complex which provides functioning of immune cells. The data on the participation of CDK8/19 in regulation of intracellular signaling pathways, as well as influence of CDK8/19 on the NK cell functions, are considered. Summarizing the data presented in the literature, one may emphasize that there is an extensive mutual influence of NK cells and trophoblast cells in decidual lining of uterus during pregnancy, thus leading to a changes in phenotype and functions of these cells. Experimental studies are required on the contribution of molecular mechanisms involved in transcription and translation processes to the biology of NK cells, and their role in maintaining interactions between NK cells and trophoblast cells, including the pathways involving CDK8/19.

Intercellular communication plays a huge role in the vital activity of living organisms. At present, far less studied is distant cellular communication, in which, along with autocrine and paracrine regulations by soluble factors (e.g. cytokines and growth factors), of particular interest is communication by means of microparticles via their ligand-receptor interaction with target cells, direct membrane fusion, or internalization by endocytosis. This study aimed at evaluating in vitro the effect of microparticles produced by natural killer cells of the NK-92 cell line on the content and activation of markers associated with apoptosis initiation in trophoblast cells of the JEG-3 cell line. Microparticles derived from NK-92 cells caused caspase-8 activation in trophoblast cells with the formation of an intermediate fragment and no final cleavage to active caspase-8. We found no significant changes in the content of the various cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (c-FLIP) isoforms (long isoform, FLIP L ; short isoform, FLIP S ) in trophoblast cells after their treatment with microparticles derived from natural killer cells. In contrast, distant interaction of trophoblast cells with natural killer cells modeled by the transwell system increased the content of FLIP S in trophoblast cells. We demonstrated that microparticles produced by natural killer cells were able to transfer their cargo to target cells, including the cytotoxic protein granzyme B. Furthermore, we could observe an increase in the caspase-3 and caspase-9 activities in trophoblast cells.

During pregnancy, uterine NK cells interact with trophoblast cells. In addition to contact interactions, uterine NK cells are influenced by cytokines, which are secreted by the cells of the decidua microenvironment. Cytokines can affect the phenotypic characteristics of NK cells and change their functional activity. An imbalance of pro- and anti-inflammatory signals can lead to the development of reproductive pathology. The aim of this study was to assess the effects of cytokines on NK cells in the presence of trophoblast cells in an in vitro model. We used TNFα, IFNγ, TGFβ and IL-10; the NK-92 cell line; and peripheral blood NK cells (pNKs) from healthy, non-pregnant women. For trophoblast cells, the JEG-3 cell line was used. In the monoculture of NK-92 cells, TNFα caused a decrease in CD56 expression. In the coculture of NK cells with JEG-3 cells, TNFα increased the expression of NKG2C and NKG2A by NK-92 cells. Under the influence of TGFβ, the expression of CD56 increased and the expression of NKp30 decreased in the monoculture. After the preliminary cultivation of NK-92 cells in the presence of TGFβ, their cytotoxicity increased. In the case of adding TGFβ to the PBMC culture, as well as coculturing PBMCs and JEG-3 cells, the expression of CD56 and NKp44 by pNK cells was reduced. The differences in the effects of TGFβ in the model using NK-92 cells and pNK cells may be associated with the possible influence of monocytes or other lymphoid cells from the mononuclear fraction.