Abundant perforin expression at the maternal-fetal interface: guarding the semiallogeneic transplant?

Effects of gestational age on blood cortisol and prolactin levels during pregnancy in malaria endemic area

BACKGROUND

The hormonal shift occurring in pregnant women is crucial for the outcome of pregnancy. We conducted a study in pregnant women living in a malaria endemic area to determine the potential effect of gestational age on the modulation of the endocrine system by cortisol and prolactin production during pregnancy.

METHODS

Primigravidae and multigravidae with a gestational age between 16-20 weeks were included in the study and followed up to delivery and 6-7 weeks thereafter. Venous blood was collected at scheduled visit: Visit 1 (V1; 16-20 weeks of amenorrhea), Visit 2 (V2; 28 ±1 weeks of pregnancy), Visit 3 (V3; 32 ±1 weeks of pregnancy), Visit4 (V4; delivery) and Visit5 (V5; 6-7 weeks after delivery). In addition, a cord blood sample was also collected during labour at delivery. Nulliparous and primiparous/multiparous non-pregnant women were enrolled in the control group. Cortisol and prolactin plasma concentrations were measured using ichroma II and i-chamber apparatus. Light microscopy was used to detect Plasmodium falciparum infections. A linear mixed-effects regression (LMER) model was used to assess the association between the variation of cortisol titres and prolactin levels during the pregnancy and the post-partum.

RESULTS

Results showed that cortisol and prolactin levels in the peripheral blood were globally up-regulated during pregnancy. Concentrations of cortisol during follow-up was significantly higher in primigravidae than in multigravidae during the whole pregnancy (p<0.024). Moreover, the level of prolactin which was higher before delivery in primigravidae reversed at delivery and postpartum visit, but the difference was not statistically significant during the follow-up (V1 to V5) (p = 0.60). The cortisol level in peripheral blood at delivery was higher than that in the cord blood, and conversely for prolactin. Cortisol and prolactin levels decreased after delivery, though the level of prolactin was still higher than that at enrolment. An increase of one unit of prolactin was associated with the decrease of the average concentration of cortisol by 0.04 ng/ml (p = 0.009). However, when cortisol increases with one unit, the average concentration of prolactin decreases by 1.16 ng/ml (p = 0.013).

CONCLUSION

These results showed that the up-regulation effects of cortisol and prolactin are related to gestational age. A The downward regulation effect that both hormones have on each other during the pregnancy when each increase to 1 unit (1.0 ng/ml) was also reported.

The Functional Diversity of Tissue-Resident Natural Killer Cells Against Infection

For decades, studies of natural killer (NK) cells have focused on those found in peripheral blood (PBNK cells) as the prototype for NK cell biology. Only recently have researchers begun to explore the diversity of tissue-resident NK (tr-NK) cells. While tr-NK cells were initially identified from mice parabiosis and intravascular staining experiments, they can also be identified by tissue retention markers such as CD69, CD103, and others. More importantly, tr-NK cells have distinct functions compared to PBNK cells. Within the liver, there are diverse subsets of tr-NK cells expressing different combinations of tissue-retention markers and transcription factors, the clinical relevance of which are still unclear. Functionally, liver tr-NK are primed with immediate responsiveness to infection and equipped with regulatory mechanisms to prevent liver damage. When decidual NK (dNK) cells were first discovered, they were mainly characterized by their reduced cytotoxicity and functions related to placental development. Recent studies, however, revealed different mechanisms by which dNK cells prevent uterine infections. The lungs are one of the most highly exposed sites for infection due to their role in oxygen exchange. Upon influenza infection, lung tr-NK cells can degranulate and produce more inflammatory cytokines than PBNK cells. Less understood are gut tr-NK cells which were recently characterized in infants and adults for their functional differences. In this mini-review, we aim to provide a brief overview of the most recent discoveries on how several tr-NK cells are implicated in the immune response against infection. This article is protected by copyright. All rights reserved.

Colocalization of Granulysin Protein Forms with Perforin and LAMP-1 in Decidual Lymphocytes During Early Pregnancy

PROBLEM

Granulysin (GNLY) occurs in two forms, which have molecular weights of 9 and 15 kDa. We analyzed the cytotoxic potential of decidual lymphocytes (DLs) and peripheral blood lymphocytes (PBLs) based on the forms of GNLY that colocalizes with perforin (PER) and LAMP-1 following activation.

METHODS

The forms of GNLY were detected by using confocal microscopy. We investigated the colocalization with PER and LAMP-1 in freshly isolated and activated DLs and PBLs.

RESULTS

Activation of DLs and PBLs by K-562 cells increased the colocalization of 9 kDa GNLY with PER and LAMP-1. K-562 cells transfected with HLA-C decreased 9 kDa GNLY colocalization with PER in DLs only. IL-15 in DLs decreased 9 kDa GNLY and LAMP-1 colocalization, but increased both 15 kDa GNLY and LAMP-1, and PER and LAMP-1 colocalization.

CONCLUSION

Activated DLs and PBLs show greater cytotoxic potential based on increased colocalization of 9 kDa GNLY and PER. HLA-C and IL-15 affect DLs, indicating their role in maintaining the pregnancy tolerance.

Potential role of heat-shock protein 70 and interleukin-15 in the pathogenesis of threatened spontaneous abortions

PROBLEM

The role of HSP70 and both its constitutive (Hsc) and inducible (Hsp) forms in the pathogenesis of threatened spontaneous abortions was investigated.

METHOD OF STUDY

Immunohistology and/or immunofluorescence was used to analyze paraffin-embedded tissue sections, and reverse transcriptase-quantitative polymerase chain reaction and flow cytometry were used for analyses of decidual mononuclear cells (DMCs) and confocal microscopy for the detection of perforin, granulysin, and lysosome-associated membrane protein-1 (LAMP-1) in decidual lymphocytes (DLs).

RESULTS

The percentage of single Hsp70(+) , Hsc70(+) , and IL-15(+) cells and mRNA levels of HSP70, CD91, and TLR4 were lower in the decidua basalis in cases of threatened miscarriages compared to that in cases of normal pregnancy. In a suspension of normal DMCs, IL-15 significantly decreased the HSP70 members and TLR4 in dendritic cells, T cells, and NK cells while increasing CD91 in NK cells alone.

CONCLUSION

Downregulation of Hsc70, Hsp70, and IL-15 expression at gene and/or protein levels might support the retention of fertilization products in cases of missed abortion and blighted ovum.

Role of tumor-associated glycoprotein-72 in the progression of endometrial adenocarcinoma: a proposed study

Endometrial adenocarcinoma is on the basis of the molecular, immunohistological and clinicopathologic features broadly divided into two groups, referred as type I and type II. Type I appears more frequently and in principle patients have a good prognosis; however a significant number of patients develop local recurrences. We hypothesize that TAG-72, expressed on endometrial carcinoma binds and internalizes endocytic pattern recognition receptors on surrounding tissue antigen presenting cells (dendritic cells and macrophages), powers their anti-inflammatory maturation program and make them capable to elicit or modulated tolerogenic immune response mediated by local T and NK effectors. This could support uncontrolled local tumor growth, deeper tumor invasion into surrounding tissues, frequent local recurrences and/or lymph node metastasis. To test this hypothesis, we propose a semi-quantitative immunohistochemical analysis of TAG-72 expression in endometrial adenocarcinoma samples and to correlate the results with clinical and pathological parameters (age, type and histological grade of the tumor, estrogen and progesterone receptor expression, invasion into the myometrium and capillaries, presence of lymph node metastases, FIGO stage, and TNM classification). It would be worthwhile to investigate the local tissue immune response in the tumor environment using tissue samples removed during surgery. These studies could elucidate the underlying immunopathological mechanisms that govern the early recurrence and possibly distant metastases of TAG-72-expressing adenocarcinomas and might help in deciding the type of treatment to be applied in a selected group of cancer patients including application of biological therapy with anti-TAG-72 antibodies, according the principle of personalized oncology treatments.

Multiple roles of perforin in hampering ERBB-2 (Her-2/neu) carcinogenesis in transgenic male mice

Perforin (pfp)-mediated cytotoxicity is one of the principal immunosurveillance mechanisms involved in the fight against cancer. However, its importance in spontaneous epithelial cancer is still poorly defined. In this study, we use a realistic mouse model that displays many features that are equivalent to human pathology to evaluate the role of pfp-dependent immunosurveillance by comparing tumor progression in rat ERBB-2 (neu) transgenic, pfp-proficient (neu(+)/pfp(+)) or pfp-deficient (neu(+)/pfp(-)) BALB/c male mice. Adult neu(+)/pfp(+) males developed poorly differentiated salivary carcinomas, whereas neu(+)/pfp(-) males displayed their salivary carcinomas noticeably earlier and showed zones of more highly differentiated tumor, indicating that pfp-mediated immunosurveillance is able not only to delay the growth kinetic of an aggressive epithelial tumor, but also to shape its histology. The role of pfp-mediated immunosurveillance appeared to be of even more dramatic importance against the less aggressive male mammary carcinomas. In neu(+)/pfp(+) males, the incidence of mammary carcinomas was a sporadic and late event. In contrast, in neu(+)/pfp(-) males their incidence was four-fold higher. This higher cancer incidence was associated with a 2-fold higher occurrence of persisting mammary remnants, a major risk factor for mammary cancer in male mice, and one that would appear to be due to pfp's previously unidentified involvement in male mammary gland rejection during embryogenesis. This work thus provides further proof of the complex role that the immune system plays in the body and gives new insight into the pathogenesis of epithelial tumors, demonstrating that the penetrance and malignancy of a tumor may be dramatically affected by pfp-dependent mechanisms.

Specific decidual CD14(+) cells hamper cognate NK cell proliferation and cytolytic mediator expression after mucin 1 treatment in vitro

Mucin 1 (MUC1) forms a glycocalyx on the surface of decidual epithelial cells that needs to be removed for successful embryo attachment. We investigated whether MUC1 affects human early pregnancy decidual CD14(+) cells and their interactions with cognate decidual natural killer (NK) cells. FITC-dextran internalisation, surface and intracellular antigen levels, and proliferation of CD14(+) and/or CD56(+) cells were analysed by flow cytometry. Magnetic separation was used to purify CD56(+) and CD14(+) cells. Uncultured CD14(+) cells expressed a negligible percentage of CD1a and CD83 molecules. They expressed lower levels of CD16, and higher levels of endocytic mannose receptors (MR), dendritic cell-specific intercellular adhesion molecule grabbing non-integrin (DC-SIGN), proinflammatory chemokine CC receptor 5 (CCR5), and CD163 receptor, than their peripheral blood counterparts. Lipopolysaccharide stimulation did not affect FITC-dextran internalisation in CD14(+) cells. MUC1 bound and internalised, in a dose-dependent manner, the carbohydrate recognition domain of MR, increasing the decoy IL-1 receptor type II and decreasing IL-15 expression in CD14(+) cells. In the presence of MUC1-treated macrophages, the expression levels of the proliferation and cytotoxic mediators (perforin, Fas ligand and TNF-related activation-induced ligand or TRAIL) was attenuated, while that of the anti-inflammatory chemokine CCL17 was increased, in NK cells compared with untreated macrophages. In conclusion, MUC1 supports the alternative activation of tissue-specific CD14(+) cells, and may restrict proliferation of NK cells and regulate their content of cytotoxic mediators. Based on the experiments with first-trimester decidual cells in vitro, we conclude that removing MUC1 from decidual tissue might help control trophoblast invasion by NK cells.

Cell death mechanisms at the maternal-fetal interface: insights into the role of granulysin

During mammal pregnancy, a sensitive balance between hormones, cytokines, humoral factors, and local cellular interactions must be established. Cytotoxic cells infiltrating the decidua are heavily equipped with cytolytic molecules, in particular perforin and granulysin. Granulysin is especially abundant in NK cells which are able to spontaneously secrete high quantities of granulysin. Besides being a potent bactericidal and tumoricidal molecule, granulysin is also found to be a chemoattractant and a proinflammatory molecule. The precise role(s) of granulysin at the maternal-fetal interface has not been elucidated yet. It is possible that it behaves as a double-edged sword simultaneously acting as an immunomodulatory and a host defense molecule protecting both the mother and the fetus from a wide spectrum of pathogens, and on the other hand, in case of an NK cell activation, acting as an effector molecule causing the apoptosis of semiallograft trophoblast cells and consequently leading to various pregnancy disorders or pregnancy loss.

Phenotype of NK cells and cytotoxic/apoptotic mediators expression in ectopic pregnancy

PROBLEM

The expression of cytotoxic/apoptotic mediators and the phenotype characteristics of uterine NK cells (uNK) in tubal ectopic pregnancy (EP) were investigated.

METHOD OF STUDY

Samples of uterine decidua and tubal mucosa as well as peripheral blood (PB) of the same women with EP were used for phenotype characterization of NK cells and detection of cytotoxic/apoptotic mediators and IL-15.

RESULTS

In tubal mucosa, perforin, FasL, granulysin and IL-15 were almost completely absent, but they were present in normal and EP uterine deciduas. TRAIL was present on trophoblast and tubal mucosa, contrary to its lack in normal and EP uterine decidua. CD16⁻ CD56(dim) NK cells, mostly CD94⁻ and NKG2A⁻, predominate in tubal mucosa, whereas CD16⁻ CD56(bright) NK cells, predominantly CD94(+) and NKG2A(+) prevail in EP uterine decidua. NK cells at the EP implantation site express lower percentages of perforin and granulysin, but they express a higher percentage of TRAIL than do EP uterine decidual and PB NK cells. Lower percentage of TNF-α-expressing and IL-4-expressing NK cells were found at the implantation site compared to EP uterine decidua.

CONCLUSIONS

Authentic uNK cell population seems to be insufficient to restrict trophoblast invasion because of low expression of cytotoxic/apoptotic mediators.

Uterine natural killer (uNK) cells and their missions during pregnancy: a review

Natural killer (NK) cells are lymphocytes of the innate immune system. The aim of this review is to describe the properties and roles of NK cells in the human uterus during pregnancy. Uterine natural killer cells (uNK) constitute a major lymphocyte population during early gestation in the uterus. The uterine natural killer cells are recognized owing to their CD56(bright), CD16(-), CD3(-) phenotype. Their number increases in the first trimester with a subsequent decline as pregnancy progresses. They have been shown to be closely associated with cells of the extravillous trophoblast (EVT) and spiral arteries. They play important roles in remodeling of the spiral arteries, control of trophoblast invasion and in the development of the placenta. Some studies have shown the number and repertoire of receptors of uNK differ between women with healthy pregnancies and those with pathologic pregnancies, such as pre-eclampsia or intrauterine growth retardation. During pregnancy, the cytotoxic characteristics of the uterine killer cells are not directed towards the fetus, and scientists continue to question and explore this phenomenon with increasing evidence that these cells may perform differing beneficial roles during pregnancy. Contrary to their previously suspected "hostile" characteristics, the uterine killer cells are considered to be "friendly" and appear to be essential and very important regulators of successful implantation and pregnancy.

The human decidual NK-cell response to virus infection: what can we learn from circulating NK lymphocytes?

NK cells present in the peripheral blood respond rapidly to pathogens or pathogen-infected cells by various means including cytotoxicity and production of cytokines. Whether decidual NK (dNK) cells are able to play a similar role when the pregnant uterus is infected by viruses is still largely unknown. Decidual NK cells are generally considered as poorly cytotoxic when compared to their peripheral blood counterparts. However, we have recently demonstrated that freshly isolated dNK cells from healthy early pregnant uterus do have a cytotoxic potential mediated by the specific engagement of NKp46 activating receptor. We further found that the co-engagement of CD94/NKG2A inhibiting receptor drastically inhibits the cytolytic function of dNK. This latter observation suggests that in situ the CD94/NKG2A receptor interaction with its HLA-E specific ligand is a dominant negative regulatory mechanism that prevents unwanted dNK cell cytotoxicity in non-infected pregnant uterus. How do dNK cells behave when they are activated by virus-infected cells present at the maternal-fetal interface? Largely based on data obtained from circulating NK cells, this review briefly discusses the following questions: Does uterine viral infection promote decidual NK cell proliferative capacity in situ? Are dNK cells able to kill virus-infected autologous decidual target cells and thus limit the virus spreading to the fetus? Which viral-mediated signal(s) and molecular interactions may subvert inhibition of dNK cytotoxic potential? Does uterine viral infection promote decidual NK cell secretion of cytokines and chemokines that boost the anti-viral immune response?

Fetomaternal immunotolerance

Implantation of mammalian conceptus in uterine cavity is the result of evolutionary adaptation, through high level of physiological procedures to ensure its success. However the majority of pregnancy losses occur before or during implantation. It is expected that exploring and defining the molecular and physiological road map during the crucial time of implantation will enable us to decode and effectively treat fertility defects. Immunological, hormonal and molecular factors participate in the feto-maternal cross talk during implantation and designate the effectiveness of the process. The atypical expression of major histocompatibility complex and other protein-antigens, such as Fas/FasL and petformin in human trophoblast, the modified function of cellular constituents of the feto-maternal interface, as well as the specific role of some hormones and cytokines, represent substantive parameters of feto-maternal immunotolerance during implantation.

Critical and differential roles of NKp46- and NKp30-activating receptors expressed by uterine NK cells in early pregnancy

In early human pregnancy, uterine decidual NK cells (dNK) are abundant and considered as cytokine producers but poorly cytotoxic despite their cytolytic granule content, suggesting a negative control of this latter effector function. To investigate the basis of this control, we examined the relative contribution to the cytotoxic function of different activating receptors expressed by dNK. Using a multicolor flow cytometry analysis, we found that freshly isolated dNK exhibit a unique repertoire of activating and inhibitory receptors, identical among all the donors tested. We then demonstrated that in fresh dNK, mAb-specific engagement of NKp46-, and to a lesser extent NKG2C-, but not NKp30-activating receptors induced intracellular calcium mobilization, perforin polarization, granule exocytosis and efficient target cell lysis. NKp46-mediated cytotoxicity is coactivated by CD2 but dramatically blocked by NKG2A coengagement, indicating that the dNK cytotoxic potential could be tightly controlled in vivo. We finally found that in dNK, mAb-specific engagement of NKp30, but not NKp46, triggered the production of IFN-gamma, TNF-alpha, MIP-1alpha, MIP-1beta, and GM-CSF proinflammatory molecules. These data demonstrate a differential, controlled role of NKp46- and NKp30-activating receptors expressed by dNK that could be critical for the outcome of pregnancy and the killing of uterine cells infected by pathogens.

The possible correlation between the patient's immune tolerance level during cesaerean section and the incidence of subsequent emergency peripartum hysterectomy

Introduction. Cesarean section is an independent risk factor for peripartum hysterectomy. As a method of delivery, cesarean section may interfere with a number of molecular changes that occur at the maternal-fetal interface during the course of labor. Methods. The level of CD3, CD56, CD25, and CD69 antigen immunoreactivity was assessed by immunohistochemistry in 26 decidual tissue samples. The tissue samples were obtained from 18 women who underwent cesarean sections at term and from 8 women who underwent cesarean hysterectomies. Results. An increase in the activity and infiltration of immune cells in the decidua sampled during the spontaneous beginning of labor was observed. The further progression of labor was accompanied by a decrease in the number and activity of immune cells. The number of CD56+ and CD3+ cells in the decidua was statistically significantly lower in patients who had undergone cesarean hysterectomies than in those who had had cesarean sections at term. Conclusion. Abnormal immune response during labor may increase the risk for peripartum hysterectomy.

Early pregnancy decidual lymphocytes beside perforin use Fas ligand (FasL) mediated cytotoxicity

Decidual natural killer (NK) cells are the predominant lymphocytes at the maternal-fetal interface. They are involved in defense against virally infected, parasitized and transformed cells and may contribute to the control of trophoblast invasion. The presence of perforin and other possible cytolytic mediators suggests these functions. Cytolytic mechanisms of unstimulated and Th1 cytokine stimulated decidual lymphocytes (DL), as well as purified decidual CD56(+) cells, were analyzed against NK sensitive and resistant targets. DL were isolated from decidual mononuclear cells (DMC) cultured in the medium only or in the presence of Th1 cytokines: IL-2, IL-12, IL-15, IL-18 and their combinations (IL-12/IL-18 or IL-15/IL-18). Fas ligand (FasL), perforin and granzyme B mRNAs expression and cytotoxicity were analyzed by flow cytometry and/or RT-PCR. DL (containing 72.19+/-7.53% of CD56(+) cells), obtained from 18h-cultured DMC in the medium only, expressed perforin, FasL and granzyme B mRNAs and lysed the NK-sensitive K-562 cell line, and also the NK-resistant P815 and P815-Fas transfected cell lines. Concanamycin A, a blocker of granule exocytosis, decreased significantly K-562 lysis, but not P815 lysis. However, the addition of anti-FasL antibody diminished significantly P815 lysis as well. IL-2 and IL-15, known inducers of perforin and FasL mRNAs and protein expression, could not additionally increase P 815 cell lysis by DL cultured within DMC. These results suggest that DL cultured in DMC for 18h, have the characteristics of lymphokine-activated killer (LAK) cells and are able to use efficiently both the perforin and the FasL cytolytic pathways.

Comparison of RCAS1 and metallothionein expression and the presence and activity of immune cells in human ovarian and abdominal wall endometriomas

BACKGROUND

The coexistence of endometrial and immune cells during decidualization is preserved by the ability of endometrial cells to regulate the cytotoxic immune activity and their capability to be resistant to immune-mediated apoptosis. These phenomena enable the survival of endometrial ectopic cells. RCAS1 is responsible for regulation of cytotoxic activity. Metallothionein expression seems to protect endometrial cells against apoptosis. The aim of the present study was to evaluate RCAS1 and metallothionein expression in human ovarian and scar endometriomas in relation to the presence of immune cells and their activity.

METHODS

Metallothionein, RCAS1, CD25, CD69, CD56, CD16, CD68 antigen expression was assessed by immunohistochemistry in ovarian and scar endometriomas tissue samples which were obtained from 33 patients. The secretory endometrium was used as a control group (15 patients).

RESULTS

The lowest metallothionein expression was revealed in ovarian endometriomas in comparison to scar endometriomas and to the control group. RCAS1 expression was at the highest level in the secretory endometrium and it was at comparable levels in ovarian and scar endometriomas. Similarly, the number of CD56-positive cells was lower in scar and ovarian endometriomas than in the secretory endometrium. The highest number of macrophages was found in ovarian endometriomas. RCAS1-positive macrophages were observed only in ovarian endometriomas. CD25 and CD69 antigen expression was higher in scar and ovarian endometriomas than in the control group.

CONCLUSION

The expression of RCAS1 and metallothionein by endometrial cells may favor the persistence of these cells in ectopic localization both in scar following cesarean section and in ovarian endometriosis.

Short-term Cytolytic Mediators' Expression in Decidual Lymphocytes is Enhanced by Interleukin-15

PROBLEM

We investigated whether decidual adherent cells (DAC) and interleukin (IL)-15, in comparison to interleukin (IL)-2 affect cytolytic potential of first trimester decidual lymphocytes (DL).

METHOD OF STUDY

Decidual mononuclear cells were obtained by enzymatic digestion and density gradient centrifugation. Non-adherent DL were collected after 2-hr adherence and cultured for 18 or 72 hr with: IL-15 (0.5-5 ng/mL), IL-2 (100-1000 U/mL) or both of these cytokines, DAC (ratio 3:1 and 1:1) or DAC and anti-IL-15 antibody. Perforin, Fas ligand (FasL) and granzyme B were detected at mRNA level in indicated culture conditions. Cytolytic activity of DL against K-562, P815 and P815-Fas was measured by 2-hr PKH-26 cytotoxicity assay. The dynamics of perforin protein and mRNA expression were measured in DL after a contact with K-562 targets.

RESULTS

Interleukin-15 enhanced perforin, FasL and granzyme B transcription after 18-hr culture and prevented perforin protein downregulation, observed after DL culture. IL-2 had similar effects. DAC sustained perforin expression in DL and anti-IL-15 monoclonal antibody abrogated this effect. DAC increased cytotoxicity of DL against K-562 which was mediated by IL-15.

CONCLUSION

Interleukin-15, probably produced by DAC, upregulates cytolytic mediators' expression and perforin-mediated cytotoxicity of DL, with equal efficiency as high concentrations of IL-2.

Perforin and Fas/FasL Cytolytic Pathways at the Maternal-Fetal Interface

The immunogenetic enigma of maternal acceptance of the fetal semiallograft has been termed an immunological paradox. The first trimester decidua is heavily infiltrated with CD56(bright) CD16- uterine natural killer (uNK) cells which must be prepared to respond to potential pathogen challenges and still be able to control immune responses that allow the development of the fetus. The significant presence of cytolytic mediators, perforin and Fas/Fas ligand (FasL), at the maternal-fetal interface raises a question of their role(s) in the immunological interrelations between maternal tissues and trophoblast cells. As uNK cells in vitro lyse target cell lines (K562, P815 and P815Fas) using these effector molecules, it seems that, although immunocompetent, their cytotoxicity is not directed against trophoblast during normal pregnancy. Therefore, it is generally believed that the hormonal and Th1/Th2 cytokine balance plays an important role in the tolerance and maintenance of pregnancy. This paper gives an overview of the recent findings on the complex immunological events that occur at the maternal-fetal interface.

Perforin improves the morphogenesis of mouse placenta disturbed by IL-2 treatment

The pore-forming protein (perforin) produced by lymphocytes can induce apoptosis in target cells. In mouse placenta, although a large amount of perforin is produced by the uterine natural killer (uNK) cells, its role in the reproductive process is still not clear. Since the cytotoxicity of uNK cells can be enhanced by interleukin (IL)-2, we studied the role of perforin in the placenta of wild-type and perforin-knockout mice treated with IL-2 during days 10-14 of pregnancy. Immunohistochemistry of the wild-type mice showed that the perforin was positive in the membrane of trophoblast glycogen cells as well as the cytoplasm of uNK cells, and there was an increase in the expression level following IL-2 treatment as revealed by RT-PCR analysis, although no change was identified in fertility. In the IL-2-treated perforin-knockout mice, however, the number of live fetuses was decreased, accompanied by an increase in the weight of placentae. Examination of these placentae showed an abnormally enlarged junctional zone, occupied by a large number of the trophoblast glycogen cells and significantly few of the apoptotic cells. These findings indicate that perforin can contribute to a successful pregnancy by inhibiting the excessive growth of the junctional zone induced by IL-2.

Tolerance of the fetus by the maternal immune system: role of inflammatory mediators at the feto-maternal interface

The adaptive immune system of placental mammals has evolved to tolerate the fetus. Rejection of the fetus by adaptive immune responses is therefore a rare event, with abortion being caused more frequently by inflammation in the placenta. This review will cover recent aspects of immune privilege and the innate immune system at the feto-maternal interface, citing examples of the role played by microbial infections in fetal demise.

A DNA prime-Mycobacterium bovis BCG boost vaccination strategy for cattle induces protection against bovine tuberculosis

The variable efficacy of bacillus Calmette-Guérin (Mycobacterium bovis BCG) in protecting humans and cattle against tuberculosis has prompted a search for a more effective vaccination regimen. A prime-boost strategy was investigated in cattle naturally sensitized to environmental mycobacteria by using a combination of three DNA vaccines coding for Hsp 65, Hsp 70, and Apa for priming, followed by a boost with BCG prior to experimental challenge with virulent M. bovis. Controls were vaccinated with DNA or BCG alone or were not vaccinated. The immune responses were monitored throughout the study, and protection was assessed based on reductions in the numbers of lesions and viable mycobacteria in lymph node samples. Vaccination with BCG alone or with a DNA prime-BCG boost regimen induced high levels of antigen-specific gamma interferon (IFN-gamma) in whole-blood cultures. In the prime-boost group there were fewer animals with severe lung lesions, fewer lymph nodes with lesions per animal, a smaller proportion of animals with lesions, lower mean lung and lymph node lesion scores, and less M. bovis isolated from retropharyngeal and thoracic lymph nodes compared to the results obtained for the nonvaccinated animals. The prime-boost regimen induced significant enhancement of protection in six parameters, compared with significant enhancement of protection in only two parameters for BCG alone. In addition, following challenge, in vitro IFN-gamma responses against ESAT-6 and CFP-10, as well as bovine tuberculin-induced skin test and in vitro IFN-gamma responses, were identified as immunological markers that predicted protection. The use of the prime-boost strategy suggested that a combination of vaccines may be better than a single vaccine for protection against tuberculosis.

Syngeneic pregnancy induces overexpression of natural killer T cells in maternal liver

Conditions such as stress, infection, autoimmune disease, etc. elevate the number and function of extrathymic T cells that are generated mainly in the liver. As primitive, self-reactive clones of T cells that coexpress receptors of the natural killer (NK) lineage, they mediate cytotoxicity against altered self, malignant and infected cells and have the unique potential to rapidly secrete large amount of T helper 1 (Th1) or Th2 cytokines. To elucidate whether some of these changes occur even during the syngeneic pregnancy, we made phenotypic and functional characterization of mononuclear lymphatic cells (MNLCs) isolated from the liver and spleen of pregnant C57BL/6 mice, testing their cytotoxicity against syngeneic thymocytes as well as against NK- and lymphokine-activated killer (LAK)-sensitive targets. The data have shown that on the sixteenth day of syngeneic pregnancy TCRint, NK1.1+ and IL-2Rbeta+ cells were accumulated in the liver, while the quantities of CD4+ and CD8+ T cells and total number classical NK (NK1.1+CD3- or IL-2Rbeta+CD3-) cells were increased in the spleen. Pregnancy-activated hepatic and splenic MNLCs were more cytotoxic against syngeneic thymocytes, YAC-1 and P815 targets, suggesting that the maternal liver is a main producer of autoreactive NKT clones, which subsequently augment NK- and LAK cell-mediated cytotoxicity in the liver and spleen.

Hemophagocytic lymphohistiocytosis is associated with deficiencies of cellular cytolysis but normal expression of transcripts relevant to killer-cell-induced apoptosis

In 65 patients with hemophagocytic lymphohistiocytosis (HLH), we found an as yet undescribed heterogeneity of defects in cellular cytotoxicity when assay conditions were modified by the incubation time, the presence of mitogen, or interleukin-2 (IL-2). The standard 4-hour natural killer (NK) test against K562 targets was negative in all patients. In patients deficient in type 1 (n = 21), type 2 (n = 5), and type 4 (n = 8) HLH, negative NK function could be reconstituted by mitogen, by IL-2, or by prolongation of the incubation time (16 hours), respectively. Most patients (n = 31) displayed the type 3 defect, defined by a lack of any cellular cytotoxicity independent of assay variations. The characteristic hypercytokinemia also concerned counterregulatory cytokines, such as proinflammatory interferon-gamma (IFN-gamma), simultaneously elevated with suppressive IL-10 in 38% of types 1-, 2-, and 4-deficient patients and in 71% of type 3-deficient patients. Elevated IFN-gamma alone correlated with high liver enzymes, but sCD95-ligand and sCD25 did not-though these markers were expected to indicate the extent of histiocytic organ infiltration. Outcome analysis revealed more deaths in patients with type 3 deficiency (P =.017). Molecular defects were associated with homozygously mutated perforin only in 4 patients, but other type 3 patients expressed normal transcripts of effector molecules for target-cell apoptosis, including perforin and granzyme family members, as demonstrated by RNase protection analysis. Thus, target-cell recognition or differentiation defects are likely to explain this severe phenotype in HLH. Hyperactive phagocytes combined with NK defects may imply defects on the level of the antigen-presenting cell.

IL-18 is present at the maternal-fetal interface and enhances cytotoxic activity of decidual lymphocytes

PROBLEM

Perforin expressing uterine natural killer (uNK) cells are under complex cytokine influence. The aim of the study was to investigate the presence and role of interleukin (IL)-18 on NK cytolytic potential at maternal-fetal (M-F) interface.

METHOD OF STUDY

Peripheral blood cells and decidual tissue were obtained from elective pregnancy termination of normal human 6-10-week-old pregnancies. Perforin expression and cytolytic activity of peripheral blood (PBL) and decidual lymphocytes (DL) were analyzed by flow cytometry. IL-18 positive decidual adherent cells (DAC) were detected by the same method. Interleukin-18 and IL-18 receptor (IL-18R) expression on the trophoblastic cells was detected by immunohistology using biotinylated anti-IL-18 and IL-18R monoclonal antibodies.

RESULTS

The IL-18 added in a dose of 10 ng/mL up-regulates perforin expression and cytolytic activity of DL. Simultaneous stimulation with IL-18 and IL-12 enhanced DL cytolytic activity, while IL-18 combined with IL-10 or IL-15 did not show this effect. Cytolytic activity of PBL was up-regulated by IL-18 as well, and this effect was enhanced by the addition of IL-12 and IL-15. Interleukin-18 did not affect perforin-protein expression in cultured PBL. Approximately 20% of DAC were IL-18 positive and these cells were mostly human leukocyte antigen (HLA)-DR negative. IL-18R positive cells were found on syncytiotrophoblast cell layer, interstitial tissue cells of villi and fetal blood cells. There was no detectable IL-18 staining on trophoblast cell layer on villi, but strong staining of fetal blood cells in villous vessels.

CONCLUSION

These are first results showing IL-18R expression, but not IL-18 expression on villous trophoblastic cells, as well as enhancement of perforin expression and NK cytolytic potential of DL under the influence of IL-18. IL-18 in concert with other cytokines and hormones could play an important role in the regulation of cytolytic potential of first trimester pregnancy decidual and peripheral blood NK cells.

Progesterone induced blocking factor (PIBF) mediates progesterone induced suppression of decidual lymphocyte cytotoxicity

PROBLEM

Progesterone induced blocking factor (PIBF) is a mediator of progesterone that blocks peripheral blood lytic natural killer (NK) activity. Progesterone or PIBF stimulated decidual macrophages block up-regulation of perforin expression in decidual lymphocytes (DL). Therefore, we investigated whether progesterone regulates cytotoxicity of DL. METHOD OD STUDY: Decidual mononuclear cells were cultured with progesterone. PIBF, progesterone and anti-PIBF antibody or in the medium only. Cytolytic activity of non-adherent DL was measured by PKH-26 (red) 2 hr cytolytic assay and flow cytometry. Perforin positive DL were detected by immunofluorescency and PIBF-positive cells by immunohistology.

RESULTS

Progesterone and PIBF, in a dose-dependent manner decreased cytotoxicity of DL against K-562 targets, and perforin egzocytosys was blocked. Anti-PIBF antibodies reversed the progesterone mediated reduction in cytolytic activity of DL. PIBF positive cells were found in first trimester pregnancy decidua.

CONCLUSION

The results indicate possible role for PIBF, as a mediator of progesterone in regulation of DL cytolytic activity at the maternal-foetal (M-F) interface.

Heat shock fusion protein gp96-Ig mediates strong CD8 CTL expansion in vivo

PROBLEM

As shown previously, gp96-Ig peptide complexes secreted by an ovalbumin transfected tumor (EG7) mediate strong, specific tumor immunity through a CD4 T cell independent CD8+ CTL response. In this study, we set out to develop a system to quantitatively determine the CD8 CTL response to gp96-Ig and to evaluate the influence of an established wild type tumor.

METHODS

Secreted heat shock protein gp96-Ig was constructed by replacement of the endoplasmic reticulum retention signal with the Fc portion of IgGI, transfected into EG7 (EG7-gp96-Ig) and used to induce CD8+ CTL expansion in vivo. Adoptively transferred, ovalbumin specific T-cell receptor (TCR) transgenic CD8+ cells (OT-1) responded with clonal expansion to the immunization with EG7-gp96-Ig. OT-1 expansion was quantitated with K(b-peptide)-tetramers by flow cytometry.

RESULTS

In response to primary immunization with EG7-gp96-Ig, OT-1 expand from an initial frequency of 0.5 to 25% of all CD8 cells, and to 50% of all CD8 cells after a booster immunization. Endogenous ovalbumin specific CD8 cells also expand strongly. Antigen specific effector function was measured by enzyme-linked immunosorbent spot-forming cell assay (ELISPOT) for interferon-gamma (IFN-gamma). While effector function was strongly induced by secreted gp96-Ig, not all expanded OT-1 produce IFN-gamma. EG7 does not cause OT-1 expansion, but rather induces anergy. If OT-1 are transferred into wild type EG7 tumor bearing mice to induce anergy of OT-1, immunization with EG7-gp96-Ig can partly overcome unresponsiveness.

CONCLUSIONS

We conclude that secreted gp96-Ig is a powerful mediator of specific CD8+ CTL responses in vivo. Secretory gp96 mimics release of gp96 by damaged or necrotic cells that is able to activate dendritic cells without CD4 help. Gp96-Ig associated peptides have not been selected by binding to major histocompatibility complex (MHC). Specific immunization by secreted gp96-Ig therefore is expected to occur also in allogeneic settings.

Immunity in neonates

Passively derived maternal immunity hampers active immunization of newborns. Further, an immature immune system contributes to a weak and Th2 polarized immunity. This state of immunity in early life sustains endemic infections in man and continuous reinfections in animal herds. The endemic infections of the young occur preferentially when the immune system is still functionally immature and when the low levels of maternal antibodies are no longer protective but yet blocks protective immune responses. Vaccines overcoming these problems would have strong positive effects on the herd health and environmental benefits. The Th2 bias of the newborn is mediated by high levels of progesterone and Th2 cytokines produced in the maternal-fetal interface. The activity of the innate system is enhanced in the mother during the prepartus period, certainly having effects on the offspring. Newborn, 2-days-old, mice can be primed with Sendai virus envelope proteins as model antigens to induce Th1 or Th2 responses, dependent on the supplementation of the virus antigen formulation with Th1 or Th2 adjuvants. This priming has a strong life-long effect when complemented with subsequent boosts. However and importantly this priming effect can be modulated by adjuvants focusing for Th1 and Th2 when applied to the mice at 6 weeks of age, i.e. when they are immunologically adult. It has been shown in various species, besides mice, i.e. dog, sheep, horse and seal, that a strong Th1 driving adjuvant can induce immune response and protection in newborns when conventional vaccines fail. In conclusion, the Th2 bias prevailing around partus can be overcome by appropriate immunological treatments, permitting effective vaccination and protective immunity in the newborn.

Accumulation of CD16+ cells with secretion of Ksp37 in decidua at the end of pregnancy

PROBLEM

Maternal cellular immunity is thought to be in a state of tolerance during pregnancy, but the precise mechanism of immunomodulation is not yet known. We investigated a novel serum protein, killer-specific secretory protein of 37 kDa (Ksp37), produced by cytotoxic lymphocytes, during pregnancy.

METHOD OF STUDY

The level of Ksp37 was determined by enzyme linked immunosorbent assay (ELISA) in the sera of healthy pregnant women. Intracellular Ksp37 expression in mononuclear cells, isolated from peripheral blood and decidua at parturition, was examined with a flow cytometer.

RESULTS

Serum Ksp37 levels significantly increased at late pregnancy, compared with non-pregnant controls and the first trimester of pregnancy. The flow cytometric analysis exhibited that Ksp37 was mainly expressed in CD16+ natural killer (NK) cells in decidua of term placenta.

CONCLUSIONS

Serum Ksp37 level was elevated at late gestational period. CD16+ NK cells in decidua seem to be a main maternal source of Ksp37. Innate immunity, with CD16+ NK cells, may play important roles near parturition.

Peri-partum changes in the intraepithelial lymphocyte population of sheep interplacentomal endometrium

PROBLEM

Previous studies have shown that the proportion of gammadeltaTCR+ large granulated lymphocytes (LGLs) increased markedly during pregnancy and declined dramatically by 2 days after parturition in sheep interplacentomal uterine epithelium. In the present study, the distribution, dynamics and fate of these cells, just before, during and immediately after parturition are described.

METHODS OF STUDY

Interplacentomal tissues were collected at 140 days postcoitus (dpc), 148 dpc, during parturition, 1-2 hr postpartum, 1 day postpartum (dpp) and 3 dpp, and were studied using light and electron microscopy, and immuno histochemistry. Uterine washings were collected at 148 dpc and examined for the presence of LGLs. Semi-thin Araldite sections taken at different stages were used to quantify the intraepithelial LGLs, non-granulated lymphocytes (NGLs) and apoptotic cells, whereas frozen sections were used to quantify CD45R+, CD8+ and gammadeltaTCR+ intraepithelial lymphocytes (IELs).

RESULTS

A dramatic decline in the proportion of IELs in the luminal epithelium during parturition was observed, mainly because of the decline in CD45R+, CD8+ and gammadeltaTCR+ IELs. There was also a significant decline in the number of granules/ LGL at parturition. This was accompanied by the presence of apoptotic cells of which some were LGLs. The proportions of IELs, LGLs and apoptotic cells markedly increased at 3 dpp. LGLs were found both in uterine washings at 148 dpc and in the uterine lumen at 3 dpp. Apoptosis of glandular epithelial cells was also evident at parturition and markedly increased at 1 dpp.

CONCLUSIONS

Our results demonstrated that the dramatic decline in the proportion of gammadeltaTCR+ LGLs at parturition was because of de-granulation, apoptosis and migration of these cells into the uterine lumen.

[HLA molecules, immunity and gestation]

During pregnancy, the fetus develops particularly efficient molecular regulatory mechanisms to prevent possible maternal anti-paternal alloimmune response and avoid viral spreading from maternal tissue. Among the different mechanisms, there has been noted a selective expression of HLA molecules on trophoblast cells: the absence of HLA class II and of polymorphic HLA-A and HLA-B expression but presence of both non polymorphic HLA-G and HLA-E class Ib as well as of HLA-C class Ia. The functional consequences of such a particular pattern of HLA expression in gestation are examined here.

Expression of RCAS1 and FasL in human trophoblasts and uterine glands during pregnancy: the possible role in immune privilege

Pregnancy is an immunological balancing act. Trophoblasts do not express MHC class I or II, except HLA-C and G, but express Fas ligand (FasL), which confers immune privilege. RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) has recently been recognized to play a role in immune evasion of the tumour cells. We therefore studied the involvement of RCAS1 and FasL in the infiltration of NK cells by examining the curettaged uterine contents of 20 cases of early stage of pregnancy. The cases were clinically divided into two groups; curettage was performed (A) due to the absence of foetal heart beats, and (B) due to spontaneous uterine bleeding and abortion. In group A, RCAS1 was expressed in the uterine glands and extravillous cytotrophoblasts, as was FasL. Infiltration of NK cells around the uterine glands was scarcely detected. In contrast, in group B, expression of both RCAS1 and FasL was strikingly decreased in both the level of expression and the numbers of RCAS1/FasL-positive cells and massive infiltration of NK cells was frequently detected around the uterine glands. These findings suggest that a reduction in RCAS1 and FasL expression seems to be closely associated with activation and infiltration of maternal NK cells and destruction of uterine glands, resulting in rejection of the foetus. Thus, expression of RCAS1 and FasL in the uterine glands and cytotrophoblasts may play a role in the downregulation of the maternal immune response, thereby maintaining pregnancy at early stage.

Peripheral T/Natural killer-cell lymphoma involving the female genital tract: A clinicopathologic study of 5 cases

Malignant lymphoma of the female genital tract (FGT) is rare. In this study, 5 peripheral T/natural killer (NK)-cell lymphomas (PTCLs) involving the FGT are reported. They include 2 from the uterus and 1 each from ovary, uterus and ovary, and vagina, and were detected between 1996 and 2000. One of the 2 ovarian tumors was bilateral. In all cases, the FGT was the initial site of clinical presentation of disease. Age at presentation ranged from 21 to 52 years (median, 36 years). One case was stage I disease, 2 were stage II, and 2 were stage IV. All 5 tumors were positive for CD3epsilon, and 3 harbored the Epstein-Barr virus, although the detailed immunophenotypic profiles varied. Three were diagnosed as nasal type T/NK-cell lymphoma, 1 as anaplastic large-cell lymphoma (anaplastic lymphoma kinase [ALK]-positive), and 1 as unspecified PTCL of cytotoxic phenotype, according to the forthcoming World Health Organization classification. Four of 5 patients received laparotomy and chemotherapy. Four patients (in stages II and IV) died of disease within 16 months of the initial diagnosis, whereas only 1 patient (in stage I) is alive without disease at 39 months of follow-up. Our experience in this series provided clinically relevant information on diagnosis, treatment, and outcome for extremely rare tumors of the FGT.