O. L. Gorbunova

The Role of Kisspeptin in Immune Tolerance Formation during Pregnancy

258 In immunological terms, pregnancy is physiologii cal tolerance of the maternal immune system to the genetically alien fetus [1]. The most important mechh anism of tolerance formation is increase in the number of adaptive T regulatory cells (aTreg) suppressing the immune response, decrease in the content of interleuu kine 17 (ILL17) of T helper lymphocytes (Th17) [1, 2] stimulating cytotoxic reactions, and induction of the enzyme indolamin 2,3 dioxygenase (IDO) by antigenn presenting cells (APC), which promotes the formation of local immune tolerance in decidua [3]. Establishing the causes of formation of immune tolerance in pregnancy is important for understanding not only the mechanism of coexistence of two genetii cally alien organisms, but also the induction of carr cinogenesis. Hormones are important modulators of the functional activity of cells of the immune system. This modulation is especially pronounced in the case of the enzymes produced by the placenta [4]. The recently discovered hormone kisspeptin, which regulates the function of the gonadostat at the hypothalamus level [5], is produced by the placenta during pregnancy, and, as a result, it appears in the maternal systemic circulation [4]. Its immunomoduu latory effect has been studied for a short time yet [6], but it is already known that cells of immune system express specific membrane receptors for it [7]. The purpose of the study was to determine the role of kisspeptin in the regulation of formation of funcc tionally active aTreg and Th17, as well as IDO express sion by monocytes. It has been shown that kisspeptin increases the forr mation of aTreg cells (CD4 + FOXP3 + CTLAA4 + GITR +) from TGFFβ1primed CD4 + Т cells at concentrations specific for trimesters I–III of pregnancy, thereby enhancing the production of ILL10 by CD4 + Т cells. At the same time, kisspeptin decreases the differentiaa tion of Th17 cells and secretion of ILL17A by СD4 + Т cells. At the concentration corresponding to trimester II of pregnancy, the hormone significantly enhances the lipopolysaccharideeinduced IDO activity of monocytes. Thus, kisspeptin is a new factor of the forr mation of immune tolerance during normal pregg nancy that has not been taken into consideration pree viously. In the study, we used a fractionated suspension of mononuclear cells of peripheral blood (MNCs) of six healthy nonpregnant women of reproductive age (from 23 to 37). The mononuclear cell suspension was obtained by centrifugation in a ficoll–verografin denn sity …

The role of pregnancy-associated hormones in regulation of expression of molecules responsible for NK cell functional activity

261 The phenomenon of tolerance of the immune syss tem of the mother to the genetically alien fetus is an urgent problem of reproductive immunology, in the framework of which analysis of the role of hormones in the immunity regulation is the most important line of research. It is known that, in the period of early pregg nancy, natural killers (NK cells) are the dominant population among lymphoid cells localized in the decidual membrane [1]. NK cells with the CD16 + CD56 dim phenotype account for over 90% of peripheral NK cells and exhibit high cytoxicity comm pared to CD16 – CD56 bright [2]. It is suggested that decidd ual NK cells mature from peripheral CD16 – CD56 bright lymphocytes migrating to the uterus [3]. During pregnancy, the cytotoxic potential of the NKKcell population decreases due to a decrease in the percentage of CD16 + CD56 dim lymphocytes. At the same time, the increased concentration of CD16 + 56 dim NK cells in the peripheral blood of women is associated with habitual miscarriage of pregg nancy [4], which is related to their ability to lyse cells of trophoblast [2]. In turn, CD16 – CD56 bright NK cells express inhibitory receptors, such as NKG2A and LILRB, due to which they fulfill an immunotrophic function instead of the cytolytic one [2]. For instance, CD16 – CD56 bright cells directly participate in implann tation, neoangiogenesis, and support of pregnancy [3]. In addition, NK cells potentiate the induction of TT regulatory lymphocytes, which leads to formation of immunologic tolerance in the period of pregnancy [5]. Along with CD16 molecule, the activation recepp tors NKG2D and NKp46 are responsible for the cytoo toxic function of NK cells, the latter is constitutionally expressed over the entire population of NK cells and serves as the main marker for their identification [6]. It is known that hormones can determine the funcc tional activity of the immune system cells [7]. The most physiologically important, from this point of view, are hormones that appear in the woman body only during pregnancy—chorionic gonadotropin (CG) and estriol (Е 3). Apart from this, the immunoo regulation function is exercised by hormones whose level considerably increases during pregnancy due to placental synthesis. These are, first of all, leptin, ghree lin, and kisspeptin. Their important role in reproducc tion regulation is well known [8–10]; however, the modulating activity with respect to NK cells at conn …

The influence of chorionic gonadotropin and estriol on NK cell phenotype and functional activity

The influence of chorionic gonadotropin (CG) and estriol (Е3) at the concentrations typical of pregnancy on the expression of phenotypic markers and cytokine production by separated NK cells has been studied. It has been found that these hormones increase the percentage of CD56bright L-selectin+ NK cells, but also stimulate the expression of the inhibitory molecule NKG2A in the lymphocytes. In addition, Е3 and CG stimulate the production of TGF-β, inhibiting the secretion of all other cytokines by separated NK cells. In general, these hormones contribute to the formation of the phenotype and cytokine spectrum characteristic of the regulatory NK3 subpopulation of NK cells during pregnancy.

Roles of leptin and ghrelin in the regulation of the phenotype and cytokine production by NK cells from peripheral blood

Both leptin and ghrelin used separately at the concentrations corresponding to trimesters II–III of pregnancy increase the number of CD56bright NK cells in mononuclear cell suspension; their combination also enhances the L-selectin expression on the surface of these cells in the culture. These hormones do not affect the production of TGF-β1, IL-17А, or IFN-γ by NK cells, and they inhibit the production of IL-10. Leptin decreses the IL-4 production by NKp46+ cells, but the presence of ghrelin abrogates this effect.

The effect of kisspeptin on the functional characteristics of isolated NK cells

The effect of kisspeptin at concentrations typical of pregnancy on the functional activity of isolated cytokine-primed NK cells has been investigated. The hormone has been shown to promote an increase in the proportion of CD56bright NK cells, as well as an increase in the L-selectin expression on the cell surface. Assessment of cytokine levels has shown that kisspeptin suppresses the production of IL-4, IL-10, and IFN-γ while stimulating the production of TGF-β by isolated NK cells. The overall effect of the hormone investigated consisted in the formation of a phenotype and a cytokine spectrum characteristic of the regulatory NK3 subpopulation of NK cells in pregnancy.

Role of CD40-Dependent Signal in Induction of Recombinase RAG-1 Expression in Peripheral T Cells of Patients with Autoimmune Diabetes Mellitus

We studied the mechanisms of induction of recombinase activity in peripheral T cells of patients with autoimmune type 1 diabetes mellitus. It was shown that the presence of CD40 on T cell membrane (not typical of these cells) is crucial for this process: expression of recombinase RAG-1 in diabetic patients was detected primarily in αβTCR+CD40+ lymphocytes; targeted CD40-dependent activation of intact T cells in vitro increases, while blockade of CD40 signal in the culture of stimulated T cells abolishes recombinase expression.

Regulation of phenotypic maturation of intact and interleukin-2-activated NK and NKT cells by chorionic gonadotropin

The explanation of mother immune system tolerance to genetically allogenic fetus is a topical issue ofreproductive immunology, whose important branch isthe study of the role of hormones in immune systemcontrol. In terms of maintaining normal pregnancy,chorionic gonadotropin (CG) is the key hormonehaving evident immunomodulatory properties [1, 2].Natural killer cells (NK cells), together with the Tcells fulfilling the functions of natural killer cells(NKT cells), play a significant part during pregnancy.It is known that NK and NKT cells lyse not only targetcells infected with intracellular pathogens, but alsoneoplasms, as well as cells of the trophoblast [3, 4].Moreover, NKT cells actively produce cytokinesinducing type 2 immune response [5, 12].Interleukin (IL2), increasing the NK and NKTcell cytotoxic potentials [1] and trasforming NK cellsinto lymphokineactivated killers (LAK cells) capableof lysing trophoblasts [6], is one of essential activationfactors for NK and NKT cells. It is known that thesyncytioblast releases IL2 into the matricular–placentary compartment during pregnancy [7]. Thus,mother immune system cells simultaneously contactCG and IL2 in the hemochorial zone.The aim of our research was to estimate the influence of CG on the phenotypic maturation of intactand IL2activated NK and NKT cells.We obtained new facts proving that CG promotesphenotypic maturation of intact NK and NKT cells.IL2 significantly increases only the number of NKcells, without affecting the level of NKT lymphocyteswith CD16 expression, which indicates phenotypicmaturation. Upon IL2 stimulation, CG at concentrations normal for the first pregnancy trimester suppresses the NKactivating IL2 effect. At the sametime, IL2activated NKT cells become more susceptible to the differentiation hormone activity.A mononuclear leukocyte suspension from peripheral blood of healthy nonpregnant women during thefollicular phase of the menstrual cycle (

Hormonal Regulation of Dendritic Cell Differentiation in the Thymus

We studied the effect of hormones estriol, ghrelin, kisspeptin, and chorionic gonadotropin in concentrations corresponding to their content in the peripheral blood in each trimester of pregnancy on the expression of membrane molecules on myeloid and plasmacytoid dendritic cells of the thymus. It was found that thymic myeloid dendritic cells are sensitive to the action of estriol and kisspeptin. Estriol in a concentration of the first trimester of pregnancy reduces the number of myeloid dendritic cells expressing receptor for thymic stromal lymphopoietin (CD11c+TSLP-R+) and inhibitory molecule B7-H3 (CD11c+CD276+). In contrast to estriol, kisspeptin regulates the processes of differentiation of thymic myeloid dendritic cells in concentrations typical of the second-third trimesters and reduced their total number (CD11c+) and the number of cells expressing TSLP-R (CD11c+TSLP-R+). Estriol and kisspeptin do not affect the total number of plasmacytoid dendritic cells (CD303+) and expression of TSLP-R and CD276 by these cells. Ghrelin and chorionic gonadotropin in the studied concentrations had no significant effect on the total number of thymic myeloid and plasmacytoid dendritic cells and on the expression of membrane molecules of TSLP-R and CD276.

Role of Kisspeptin and Leptin in the Development of Immune Reactivity during Pregnancy

The effects of kisspeptin, an important regulator of reproductive function, and leptin, a classical metabolic hormone, on the formation of inducible regulatory T cells (iTreg) and T helper cells that produce interleukin 17 (Th17), as well as on the activity of indoleamine 2,3-dioxygenase (IDO) have been studied. Both hormones are actively produced by the placenta and involved in the formation of a new hormonal profile during pregnancy. It was found that kisspeptin at concentrations typical for trimesters I–III of pregnancy stimulates the formation of iTreg and simultaneously inhibit Th17 induction. Regardless of the used concentration, kisspeptin increases the secretion of interleukin-10 (IL-10) and reduces the production of IL-17A in CD4+ T lymphocytes in women. At the same time leptin at physiological concentrations typical for pregnancy has the opposite effect, inhibiting the formation of iTreg without affecting the production of IL-10 in cultures of CD4+T lymphocytes and simultaneous stimulating the induction of Th17 and production of IL-17A in CD4+T lymphocytes. At the concentration corresponding to trimesters II–III of pregnancy both hormones significantly enhance lipopolysaccharide-induced activity of IDO in monocytes.

Hormonal regulation of NK cell cytotoxic activity

The effects of chorionic gonadotropin, estriol (E3), leptin, ghrelin, and kisspeptin on the intracellular expression of perforin, granzyme A, and granzyme B was studied in separated NK cells. All studied hormones except E3 are could modulate the expression of cytotoxic enzymes in NK cells by suppression of the expression of the most active proapoptotic agents, resulting in increased expression of granzyme A, which is typical of the decidual subpopulation of these lymphocytes.