[The relationship between inflammatory and immunological processes during pregnancy. Practical aspects]. / A gyulladásos és immunológiai folyamatok kapcsolata a várandósság alatt. Gyakorlati vonatkozások.

The aim of this review is to explore, in addition to revealing the biological background, new conceptual and therapeutic approaches for reproductive clinicians to provide better and more effective care for sterile and infertile couples. In humans, 75% of unsuccessful pregnancies are the result of failures of implantation, and implantation failure is the limiting factor for in vitro fertilization treatment. A modified "good" inflammation is necessary for implantation and parturition, but for most of pregnancy, inflammation threatens the continuation of pregnancy. During this period, maintaining the non-inflammatory condition is extremely important, enabling the maternal epigenetic effects to occur in the fetus, making it possible for the offspring to adapt as much as possible to the extrauterine life. In the maintenance of the non-inflammatory condition of pregnancy, a large amount of progesterone hormone produced by the placenta (after the luteo-placental shift) plays a crucial role. It has been reported that the role of inflammation during implantation is an ancestral response to the embryo as a foreign body. During normal pregnancy, this inflammation is initiated by the trophoblast and involves the suppression of neutrophil infiltration, the recruitment of natural killer cells to the site of implantation as well as the production of a range of proinflammatory cytokines. During the "implantation window", the uterus is primed to produce several inflammatory signals such as prostaglandin E2 and a range of proinflammatory cytokines, including TNF, IL6 and IFNγ. The feto-placental unit is a semi-foreign graft called a "semi allograft", and the recognition of pregnancy by the mother (host) and the resulting maternal immune tolerance is an essential part of successful pregnancy and the birth of a healthy fetus. Because of the functional or absolute reduction of circulating progesterone (due to the decreasing hormone production of the physiologically "aging" placenta after around the 36th week of pregnancy) progesterone effects become insufficient. Therefore it is unable to suppress the production of IL8 and other inflammatory cytokines and the term inflammation, leading to cervical ripening, uterus contractions and parturition ("good" inflammation). Orv Hetil. 2019; 160(32): 1247-1259.

Comportamiento de las células asesinas naturales, las dendríticas y los macrófagos, en el embarazo / Behavior of the natural killer cells, dendritic cells and macrophages in pregnancy

La implantación de un embrión semialogénico en el útero materno constituye una paradoja inmunológica y es uno de los fenómenos que abre más interrogantes dentro del campo de la Inmunología. Mientras que en un determinado momento se consideró que la interfase materno-fetal era un sitio inmunológicamente privilegiado, hoy se sabe que ocurre un reconocimiento del feto semialogénico por el sistema inmune de la madre. Sin embargo, a pesar de este reconocimiento inmunológico se han descubierto varios mecanismos que pueden explicar el porqué la madre no rechaza al feto antigénicamente diferente. Estos mecanismos incluyen, tanto factores fetales como factores locales maternos, donde están incluidos los elementos de la respuesta inmunitaria adaptativa e innata. En este trabajo se hace referencia a la importante función que desempeñan las células asesinas naturales, las células dendríticas y los macrófagos en el embarazo(AU)

The implantation of a semiallogenic embryo in the womb is an immunological paradox and is one of the phenomena that open more questions in the field of immunology. While at one point it was considered that the maternal-fetal interface was an immunologically privileged site, now it is known that a fetus semiallogenic recognition by the immune system of the mother occurs. However, despite this immune recognition several mechanisms have been discovered that may explain why the mother does not reject the fetus antigenically different. These mechanisms include both fetal factors and local maternal factors, where the elements of innate and adaptive immune response are included. In this paper we refer to the important role of natural killer cells, dendritic cells and macrophages in pregnancy(AU)

Síndrome antifosfolípido en mujeres con pérdidas recurrentes de embarazo: diagnóstico de laboratorio / Antiphospholipid syndrome in women with recurrent pregnancy loss: laboratory diagnosis

El síndrome antifosfolípido es el tipo de trombofilia adquirida más frecuente y se define como un estado de hipercoagulabilidad de causa autoimnune, que puede provocar trombosis arterial, venosa, o ambas; así como una amplia gama de complicaciones obstétricas por lo general asociadas a insuficiencia placentaria. Entre ellas están: la pérdida gestacional recurrente, la muerte fetal, la preclampsia grave precoz, la restricción del crecimiento intrauterino, el desprendimiento precoz de placenta y los partos prematuros. En general, en los países en vías de desarrollo se desconoce la magnitud del problema ocasionado por estos anticuerpos antifosfolípidos en mujeres con pérdidas recurrentes de embarazo, debido a que para el diagnóstico de esta entidad se precisa de pruebas que resultan costosas, que requieren de personal calificado para su interpretación y por otra parte, no existe uniformidad en los criterios de laboratorio utilizados por diferentes instituciones para realizar el diagnóstico. En Cuba contamos con posibilidades diagnósticas para la identificación de los anticuerpos antifosfolípidos, lo que constituye un pilar fundamental en el análisis diferencial de esta entidad obstétrica; por ello, la combinación de un diagnóstico adecuado, un minucioso seguimiento y un tratamiento certero redundarán en el éxito del embarazo(AU)

The antiphospholipid syndrome is the most common type of acquired thrombophilia and is defined as a hypercoagulable state of autoimmune cause, which can provoke arterial and/or venous thrombosis, as well as a wide range of adverse obstetric complications associated to placental insufficiency. Among them are the recurrent pregnancy loss, stillbirth, early severe preeclampsia, intrauterine growth restriction, premature placental abruption and premature births. In general, in developing countries the magnitude of the problem caused by these antiphospholipid antibodies in women with recurrent pregnancy losses is high, as tests of elevated cost for the diagnosis of this disease are needed, which also requires qualified personnel for the interpretation of results and there is no uniformity in the laboratory criteria used for diagnosis by different institutions In Cuba we have diagnostic possibilities for the identification of these antiphospholipids which is a fundamental pillar in the differential analysis of this obstetric entity; therefore, the combination of an accurate diagnosis, careful monitoring and the proper treatment, guarantees pregnancy success(AU)

Células natural killer endometriais: o que são? O que fazem? O que devemos saber? / Endometrial natural killer cells: what are they? What do they do? What do we need to know?

As células natural killer endometriais, também chamadas células natural killer uterinas, têm recebido especial atenção no campo da imunologia reprodutiva. Teorias que consideram alterações na resposta imune como uma causa de infertilidade conjugal e de falhas nos tratamentos de reprodução assistida têm ponderado um possível envolvimento negativo das células natural killer endometriais. As células natural killer são linfócitos que podem ser identificados no sangue periférico e no endométrio, apresentando diferenças fenotípicas e funcionais importantes. As células periféricas não se alteram com a fase do ciclo menstrual e implantação, sendo que as células natural killer endometriais apresentam variações durante o ciclo menstrual e período peri-implantacional, com menores concentrações durante a fase proliferativa e aumentando na segunda fase do ciclo. A célula natural killer endometriais participam nas várias fases da implantação, invasão trofoblástica, placentação e desenvolvimento fetal e no desenvolvimento da gestação humana até aproximadamente 20 semanas.

Endometrial natural killer cells have been given special attention in reproductive immunology. The relation between the endometrial natural killer cells and alterations in the immune response as a cause of couples infertility and failure in assisted reproduction treatment have been studied in several theories. Natural killer cells are lymphocytes that may be identified in peripheral blood and endometrium, with phenotypical and functional differences between them. Peripheral natural killer cells do not change with the menstrual cycle or implantation, as opposed to endometrial natural killer cells which present lower concentration in the proliferative phase and higher concentration in the luteal phase. Endometrial natural killer cells play an important role in the implantation, trophoblastic invasion, placentation, fetal development and development of the human pregnancies up to 20 weeks of gestation.

[Immunological role of progesterone in the maintenance of pregnancy]. / Papel inmunológico de la progesterona en el mantenimiento del embarazo.

Progesterone is an essential hormone for pregnancy maintenance. This hormone acts by binding to its intracellular receptor or by rapid non-genomic actions to regulate a wide variety of biological functions in the feto-placental unit. Progesterone regulates blastocyst implantation and placental development by inducing immunosuppression through type Th2 cytokines secretion. This review summarizes current research about the role of progesterone as critical regulator of expression and secretion of cytokines by T-cell and other placental cells.

Papel inmunológico de la progesterona en el mantenimiento del embarazo / Immunological role of progesterone in the maintenance of pregnancy

Progesterone is an essential hormone for pregnancy maintenance. This hormone acts by binding to its intracellular receptor or by rapid non-genomic actions to regulate a wide variety of biological functions in the feto-placental unit. Progesterone regulates blastocyst implantation and placental development by inducing immunosupression through type Th2 cytokines secretion. This review summarizes current research about the role of progesterone as critical regulator of expression and secretion of cytokines by T-cell and other placental cells.

La progesterona es una hormona esteroide muy versátil y esencial para el mantenimiento del embarazo. El principal mecanismo de acción de la progesterona es el clásico, vía receptor intracelular, regulando diversas funciones, aspectos celulares y vías moleculares implicadas en el proceso de la implantación. Asimismo existen mecanismos adicionales que no dependen de la interacción del complejo hormona receptor con la maquinaria transcripcional y que son capaces de regular rápidamente cascadas de señalización que determinarán la respuesta de la célula. En particular se ha demostrado que la progesterona ejerce efectos inmunosupresores durante la gestación al favorecer la secreción de citocinas de tipo Th2 por los linfocitos T, evento importante para regular el sistema inmunológico materno y evitar el rechazo de la placenta. El objetivo de esta revisión se centra en analizar la influencia de la progesterona en la interfase materno-fetal sobre la expresión y secreción de citocinas por las células T y no T como es el caso del trofoblasto.

Nerve growth factor in reproductive biology: link between the immune, endocrine and nervous system?

Successful pregnancy outcome requires balanced networking of the immune and endocrine system. In addition, numerous sophisticated adaptive mechanisms promote invasion of fetal tissue and facilitate tolerance. This highly sensitive and vulnerable environment may be challenged from either the maternal or the fetal site. In this overview we collect evidence of a functional role of neurotrophins, predominately nerve growth factor (NGF), in pregnancy maintenance. We demonstrate several pathways through which NGF may be involved in maintaining pregnancy and/or--if exaggerated--inducing pregnancy failure. Due to the pleiotropism of NGF, we hypothesize that NGF is mandatory for the success of pregnancy, e.g. via inhibition of paternal MHC II molecule expression on trophoblast cells. This is supported by published evidence on progesterone, the hormone of pregnancy, which maintains local levels of NGF. On the other hand, if levels of NGF are upregulated in response to environmental challenges, e.g. stress, this may result in a threat to pregnancy maintenance due to a skew towards proinflammatory cytokines and increased apoptotic cell death. Hence, we strongly suggest that NGF constitutes a functional link between the nervous, endocrine and immune system translating environmental or endocrine signals during pregnancy into an immunological answer.

Depletion of CD8+ cells abolishes the pregnancy protective effect of progesterone substitution with dydrogesterone in mice by altering the Th1/Th2 cytokine profile.

One of the most remarkable immunological regulations is the maternal immune tolerance toward the fetal semiallograft during pregnancy, which has been referred to as immunity's pregnant pause. Rejection of the semiallogeneic trophoblast cells must be selectively inhibited and pathways presumably include Th2 cytokines unopposed by Th1 cytokines. Steroid hormones, including progesterone, have similar effects. Low levels of progesterone and Th2 cytokines and high levels of Th1 cytokines are attributable for increased abortions in mammalians, which may be triggered by psychoemotional stress. Thus, the aim of the present study was to provide experimental evidence for the mechanism involved in the mediation of immune responses by endocrine signals during pregnancy and stress-triggered pregnancy failure. DBA/2J-mated CBA/J female mice were randomized in three groups: 1) control females, 2) mice exposed to stress on gestation day 5.5, and 3) mice exposed to stress and substituted with dydrogesterone, a progestogen with a binding profile highly selective for the progesterone receptor on gestation day 5.5. On gestation days 7.5, 9.5, and 10.5, mice of each group were sacrificed, and the frequency of CD8(+) cells and cytokine expression (IL-4, IL-12, TNF-alpha, IFN-gamma) in blood and uterus cells was evaluated by flow cytometry. Additionally, some mice were depleted of CD8 cells by injection of mAb. We observed that progesterone substitution abrogated the abortogenic effects of stress exposure by decreasing the frequency of abortogenic cytokines. This pathway was exceedingly CD8-dependent, because depletion of CD8 led to a termination of the pregnancy protective effect of progesterone substitution.

Cytokines during early pregnancy of mammals: a review.

This article reviews the function of cytokines during early pregnancy of mammals including the human species. Investigations concerning conceptus and other secretory proteins, their meaning for maternal recognition and maintenance of pregnancy, fetal and placental growth and differentiation, adhesion, invasion and implantation are discussed, and differences between laboratory rodents, carnivores, artiodactyls, horses and human beings elucidated and summarized. Finally topics that might be of interest for further research are emphasized.

Distributions of endometrial NK cells, B cells, T cells, and Th2/Tc2 cells fail to predict pregnancy outcome following recurrent abortion.

PROBLEM: To evaluate the ability of immunophenotypes of endometrial leukocytes from patients with histories of recurrent abortion to predict outcome of subsequent pregnancy. METHODS OF STUDY: Seventeen women with two successive spontaneous abortions with normal karyotype in the conceptus and 15 women with male-factor infertility were studied. Subsequent pregnancy outcomes in 17 recurrent abortion patients were noted; 11 had live birth, while six aborted in the first trimester. All of 15 women with male-factor infertility became pregnant after therapy, resulting in live birth in all cases. Endometrium was sampled during the peri-implantation period before subsequent pregnancy. We immunostained paraffin-embedded sections for lymphocyte markers including natural killer (NK) cell markers, CD56 and CD16, a B-cell marker CD20, T-cell markers CD3 and CD8, and a specific T-helper(Th)2 and T-cytotoxic (Tc)2 marker termed 'chemoattractant receptor-homologous molecule expressed on Th2 cells' (CRTH2). Immunoreactive cells for these antigens were counted and positivity ratios to CD45- or CD3-positive cells were calculated. These parameter were compared between 17 patients with histories of recurrent abortion and 15 control women and also compared between 11 patients whose subsequent pregnancy was successful and six patients whose subsequent pregnancy was a failure. RESULTS: Numbers of CD45+, CD56+, CD16+, CD20+, CD3+, CD8+, and CRTH2+ cells in recurrent abortion patients resembled those in controls. No significant difference in lymphocyte subset numbers or ratios was noted between patients whose subsequent pregnancy was successful and those who again aborted. CONCLUSION: We could not predict pregnancy outcome by immunophenotypic analysis of endometrium in women with recurrent abortion.

Cytokines of the placenta and extra-placental membranes: roles and regulation during human pregnancy and parturition.

Summary In an earlier, companion, review, we concluded that cytokines produced by the placenta and associated membranes are likely to be involved in control of the processes of implantation and placental development (Bowen et al., 2002). In this review, we discuss evidence that cytokines continue to be part of a paracrine/autocrine regulatory network in the placenta and membranes throughout the mid and late stages of gestation. Cytokines are involved in regulation of placental growth during these later stages of pregnancy and also function to protect the fetus from pathological organisms. The evidence, while not entirely consistent, suggests that production of certain cytokines within the extraplacental membranes is altered during normal term parturition, whereas in the villous placenta evidence of labour-associated changes is much more equivocal. Roles for cytokines have been postulated in many facets of parturition, including expulsion of the fetus by uterine contractions, membrane rupture, and dilation of the cervix. Imbalances and disruptions to the cytokine milieu have been implicated in a number of diseases of pregnancy involving abnormalities of both placental growth/establishment and initiation of parturition. Cytokine secretion induced by intrauterine infection is associated with increased occurrence or severity of some neonatal diseases. This wealth of data supports the view that cytokines are an integral part of a functional regulatory/communication network operating within the placental-maternal unit during normal gestation.

Cytokine cross-talk between mother and the embryo/placenta.

Cytokines are regulatory glycoproteins that can affect virtually every cell type in the body and have pleiotropic regulatory effects on hematopoietic, endocrine, nervous and immune systems. Chemokines, although considered as members of the cytokine superfamily, are establishing their own identity. Chemokines mediate leukocyte migration through specific G protein coupled receptors in various tissues. Recently, much evidence has suggested that cytokines and chemokines play a very important role in the reproduction, i.e. embryo implantation, endometrial development, and trophoblast growth and differentiation by modulating the immune and endocrine systems. The close correlation between the embryo and endometrium and between the placenta and decidua are mediated by sex steroid hormones, cytokines and chemokines. As a result of this closely related cross-talk, pregnancy is successfully maintained.

During pregnancy, in the context of a Th2-type cytokine profile, serum IL-6 levels might condition the quality of the synthesized antibodies.

PROBLEM: In recent years, the central role of cytokines in the immune response has been widely studied. It is considered that a T helper (Th)1-type cytokine profile is associated with the rejection phenomenon, whereas a Th2-type cytokine profile is associated with immunological tolerance. In pregnancy, the enhanced Th2/Th1 ratio seems to be necessary to fetal protection. Taking into account that a Th2-type response means antibody production by B cells, and that these antibodies could induce degradation of the paternal antigens, we investigated the quality of the antibodies produced during pregnancy and their regulation. METHOD OF STUDY: Review of previous data. RESULTS: The regulation of protective antibodies by IL-6 in a dose-dependent fashion is proposed as a hypothesis. CONCLUSION: Cytokines play a central role in the success (or failure) of pregnancy. However, the quality of the synthesized antibodies is also a regulatory key. The preferential synthesis of asymmetric immunoglobulin G antibodies during pregnancy could be one of the several pathways that lead to a successful pregnancy

Soluble HLA-G influences the release of cytokines from allogeneic peripheral blood mononuclear cells in culture.

Exquisitely regulated cytokine balance during early pregnancy is thought to be necessary for promoting survival of the fetal allograft. Our previous studies have demonstrated that membrane-bound human leukocyte antigen (mHLA-G) expressed on trophoblasts is one of the key factors in regulating cytokine balance by shifting the Th1/Th2 balance toward Th2 polarization, a favourable milieu for the maintenance of pregnancy. Given that trophoblasts secrete soluble HLA-G (sHLA-G), we examined its biological roles in comparison with mHLA-G. We cultured peripheral blood mononuclear cells (PBMC) with either the HLA-A and -B-deficient B lymphoblast cell line (721.221 cells) or the same cell line transfected with mHLA-G (721.221-G1 cells), in the presence or absence of recombinant sHLA-G. Cytokine concentrations in the culture media were determined by enzyme-linked immunosorbent assay. In contrast to mHLA-G protein, sHLA-G stimulated the release of tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, whereas it reduced the release of interleukin (IL)-3, regardless of the presence of the presence of a stimulatory effect of the mHLA-G-expressing cells. Although mHLA-G reduced the release of IL-4, sHLA-G did not have any effect. Conversely, sHLA-G stimulated the release of IL-10 whereas mHLA-G was without effect. These results suggest that sHLA-G regulates the release of cytokines from PBMC chiefly by counterbalancing mHLA-G, and thereby may play a role in maintaining pregnancy.

The expression of a progesterone-induced immunomodulatory protein in pregnancy lymphocytes.

PROBLEM: The immunological effects of progesterone are mediated by a protein, named the progesterone-induced blocking factor (PIBF). The PIBF blocks NK activity in vitro and therefore prevents the abortive effect on high NK activity in mice. Increased NK activity has been suggested to play a role in pregnancy termination; thus NK inhibitory effect of the PIBF should contribute to the maintenance of normal gestation. This study was designed to investigate the relationship between n vivo PIBF-producing capacity and in vitro cytotoxic activity of pregnancy lymphocytes, as well as the clinical status or the outcome of pregnancy. METHOD: Lymphocytes of 168 pregnant women (96 normal pregnancies, 16 showing clinical symptoms of threatened preterm pregnancy termination, 46 recurrent aborters, and 10 women sampled at the onset of spontaneous abortion or preterm delivery) were isolated on Ficoll-Paque gradient. The lymphocytes were tested for reactivity with a PIBF-specific antibody by immunocytochemistry, and simultaneously for cytotoxic activity to human embryonic fibroblast targets. RESULTS: The percentage of PIBF-positive lymphocytes in peripheral blood of healthy pregnant women was significantly higher than in that of women at risk for premature pregnancy termination. In peripheral blood of patients undergoing spontaneous pregnancy termination at the time of sampling, and in those of women showing symptoms of premature pregnancy termination we found lower than normal percentage of PIBF-positive cells. PIBF expression of the lymphocytes showed an inverse correlation with NK activity, and the rate of PIBF positive lymphocytes was related to the outcome of pregnancy. CONCLUSION: These data suggest a strong relationship between PIBF producing capacity as well as NK activity of the lymphocytes and the success of gestation.

The biological function of rabbit blastocyst peptides (RBPs).

The inhibitory effect of rabbit blastocystic peptides (RBPs) on lymphocyte transformation was studied by the method of measuring the incorporation of 3H-thymidine into DNA. The results indicated that RBPs inhibited PHA-stimulated rat and human lymphocyte transformation in vitro. In the concentration ranging from 40 to 200 micrograms/2.5 ml, the inhibition was dose-dependent. No obvious inhibitory action was found with hCG (16-128) IU/2.5 ml), progesterone (250 ng-1 microgram/2.5 ml) and pregnant rabbit serum. It was further demonstrated that RBPs at a higher dosage (200 micrograms/ml) was inhibitory to PGF2 alpha secretion. On the other hand, the 3H-leucine incorporation of rabbit endometrium was enhanced by these peptides, and this action could be blocked by the addition of actidine.

Alteration of lymphocyte reactivity in pregnant women treated with the progesterone receptor inhibitor ZK 98734.

Thirteen women during the 5th and 6th weeks of gestation were treated with a progesterone receptor blocker (ZK 98734) for pregnancy termination. Five patients received 100 mg/day of the compound, and eight patients received 50 mg/day for 4 days. Daily blood samples were obtained during the treatment period as well as on days 8 and 15 after the beginning of drug administration, and cytotoxic activity, progesterone sensitivity, and progesterone binding capacity of the lymphocytes were determined. Determination of SP-1 concentrations monitored the saturation state of trophoblastic progesterone receptors. High and low responders to the progesterone antagonist were identified. Lymphocytes of high responders treated with the 100 mg/day dose demonstrated a rapid increase of cytotoxicity, with a concomitant fall in progesterone sensitivity and progesterone binding capacity. Vaginal bleeding began as early as the 2nd day of treatment, and pregnancy was terminated by the 8th day of the treatment. Low responders receiving 100 mg/day demonstrated similar but attenuated changes. Low responders did not bleed during the first 4 days of treatment, and termination of pregnancy occurred later compared to high responders. Lymphocytes of high responders treated with 50 mg/day behaved similarly to those obtained from the low responders treated with 100 mg/day, and abortion was not completed before the 25th day after the beginning of the treatment. Lymphocytes function of low responders treated with 50 mg/day did not change significantly, the SP-1 concentration did not decline, and pregnancies continued. We conclude that a difference in sensitivity to the progesterone receptor blocker explains the selective block at trophoblastic binding sites only and the inability to block those in the lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)