Role of the Fas/Fas ligand system in female reproductive organs: survival and apoptosis

Age-related histopathological and biochemical testicular damages were ameliorated by vitamin C administration

INTRODUCTION AND OBJECTIVES

Aging is an irreversible process associated with decreased biological functions that can lead to the reduction of reproductive organs capacities in males and females. Paternal age is a significant predictor of offspring health and development. So, the aim of this study was to evaluate the effects of vitamin C on histopathological and biochemical testicular changes following aging process with a focus on stereological methods.

MATERIAL AND METHODS

For this study, 48 adult male NMRI mice were divided into two control and experimental groups. Mice in experimental group were supplemented with vitamin C (150mg/kg) including 24-h interval by oral gavage for 33 weeks. Same regime was performed for animals in control group except that vitamin C was replaced by water. Then, right testes were extracted for stereological and left testes were used for molecular analyses on weeks 8, 12, and 33.

RESULTS

Our findings showed low semen quality, decreased level of serum Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), and testosterone along with increased reactive oxygen species (ROS) production and higher apoptotic gene expression following aging. Stereological studies showed that the volume of testes, the length of seminiferous tubules, and the number of spermatogenic and none-spermatogenic cells decreased significantly during aging. Also, vitamin C consumption for 33 weeks significantly improved biochemical and histological indices. The impact of aging on male reproduction seems to be inevitable worldwide. Therefore, the use of protective and preventive remedies conserving male fecundity is very important and based on our results, vitamin C is a beneficial candidate for improving age-related testicular changes due to aging process.

Fas regulates the apoptosis and migration of trophoblast cells by targeting NF-κB

Placental trophoblast apoptosis is a major pathological feature of preeclampsia. Fas has been reported to be highly expressed in the placentas of patients with preeclampsia. However, the role and underlying mechanisms of Fas in the pathogenesis of preeclampsia have not been elucidated. In the present study, the expression of Fas in JAR human choriocarcinoma cells was overexpressed and knocked down to determine the function and possible mechanism of Fas in trophoblast cells in the progression of preeclampsia. The results of flow cytometry, Cell Counting Kit-8 and Transwell assays indicated that the overexpression of Fas promoted apoptosis, suppressed viability and impaired the migration of the human trophoblast cells. In addition, western blotting revealed that the overexpression of Fas increased the expression of nuclear factor kB (NF-kB), Bax, tumor necrosis factor α (TNF-α) and interleukin-2 (IL-2), and decreased the expression of Bcl-2 at the protein level in trophoblast cells. By contrast, the knockdown of Fas decreased the apoptosis of trophoblast cells and increased their viability and migration. In addition, the knockdown of Fas suppressed the expression of NF-κB, Bax, TNF-α and IL-2, and increased the expression of Bcl-2. Notably, the overexpression of NF-κB p65 attenuated the Fas knockdown-induced inhibition of apoptosis and acceleration of migration of the trophoblast cells. The overexpression of NF-κB in trophoblast cells also reversed the reduction in Bax expression and increase in Bcl-2 expression induced by Fas knockdown in trophoblast cells. These results indicate that Fas regulates the apoptosis and migration of trophoblast cells by targeting NF-κB, which suggests that the silencing of Fas is a promising therapeutic strategy for preeclampsia.

Immunosuppressive Protein Signatures Carried by Syncytiotrophoblast-Derived Exosomes and Their Role in Human Pregnancy

The syncytiotrophoblast (STB) of human placenta constitutively and throughout pregnancy produces and secretes exosomes - nanometer-sized membrane-bound extracellular vesicles from the endosomal compartment that convey cell-cell contact 'by proxy' transporting information between donor and recipient cells locally and at a distance. Released in the maternal blood, STB-derived exosomes build an exosomal gradient around the feto-placental unit acting as a shield that protects the fetus from maternal immune attack. They carry signal molecules and ligands that comprise distinct immunosuppressive protein signatures which interfere with maternal immune mechanisms, potentially dangerous for the ongoing pregnancy. We discuss three immunosuppressive signatures carried by STB exosomes and their role in three important immune mechanisms 1) NKG2D receptor-mediated cytotoxicity, 2) apoptosis of activated immune cells and 3) PD-1-mediated immunosuppression and priming of T regulatory cells. A schematic presentation is given on how these immunosuppressive protein signatures, delivered by STB exosomes, modulate the maternal immune system and contribute to the development of maternal-fetal tolerance.

Effect of menopausal hormone therapy on proteins associated with senescence and inflammation

BACKGROUND

Estrogen may inhibit cell senescence that contributes to age-related disorders. This study determined the effects of menopausal hormone treatments on circulating levels of markers of cell senescence.

METHODS

Growth differentiation factor 15 (GDF15), tumor necrosis factor receptor 1 (TNFR1), FAS, and macrophage inflammatory protein 1α (MIP1α) were measured in serum using multiplexed bead-based assays and compared among menopausal women participating in the Kronos Early Estrogen Prevention Study randomized to either placebo (n = 38), oral conjugated equine estrogen (oCEE, n = 37), or transdermal 17β-estradiol (tE2, n = 34). Serum levels of the senescent markers for each treatment were compared to placebo 36 months after randomization using the Wilcoxon rank sum test.

RESULTS

Serum levels of GDF15, TNFR1, and FAS, but not MIP1α, were lower in both the oCEE and tE2 groups compared to placebo. The difference in levels between treatment and placebo for GDF15, TNFR1, and FAS were greater for oCEE [-108 pg/mL (p = .008), -234 pg/mL (p = .0006), and -1374 pg/mL (p < .0001), respectively] than for tE2 [-76 pg/mL (p = .072), -105 pg/mL (p = .076), and -695 pg/mL (p = .036), respectively]. Additionally, TNFR1 showed a positive association with time past menopause (correlation = 0.255, p = .019).

CONCLUSIONS

Circulating levels of some markers of cell senescence were lower in menopausal women treated with oCEE and tE2 compared to placebo. Differences in the magnitude of effect of the two active treatments may reflect the differences in circulating levels of estrogen metabolites due to formulation and mode of delivery. These data generate new hypotheses with regard to the effects of menopause on the biology of aging.

Phenoxodiol sensitizes metastatic colorectal cancer cells to 5-fluorouracil- and oxaliplatin-induced apoptosis through intrinsic pathway

Colorectal cancer (CRC) is one of the most common types of cancer seen in the world. 5-Fluorouracil (5-Fu) plus Oxaliplatin (1-OHP) remains the backbone of CRC chemotherapeutics, but with limited success. Phenoxodiol (Pxd) is an isoflavone analog with antitumor activity against various types of cancers, and sensitizes chemoresistant cancer cells to chemotherapeutics including platinum and taxanes. This study was, therefore, undertaken to examine whether Pxd pre-treatment with conventional chemotherapeutic agent(s) 5-Fu and 1-OHP co-administration be a therapeutic strategy for CRC. Cell viability and cytotoxicity were evaluated using dimethyl-thiazolyl diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase assays. The percentage of apoptotic and necrotic cells were determined by fluorescence microscopy analysis. Besides, active Caspase-3 levels by ELISA and relative mRNA levels of Caspase 3 (CASP3), CASP8 and CASP9 genes were determined by quantitative real-time PCR (qPCR) analysis. The pre-treatment of Pxd followed by 5-Fu and 1-OHP co-administration was more effective at inhibiting cell viability than either chemotherapeutic agents treatment alone. When compared to 5-Fu with 1-OHP alone treatment, Pxd pre-treatment overwhelmingly increased apoptotic Caspase-3 activity levels in CRC cells. Moreover, qPCR analyses showed that CASP3 and CASP9 mRNA levels significantly increased after pre-treatment with Pxd followed by 5-Fu and 1-OHP treatments, compared to 5-Fu with 1-OHP alone. Our results suggested that Pxd enhanced the in vitro antitumor activity of 5-Fu and 1-OHP. Our study also suggested that Pxd may be a potential candidate agent in advanced CRC and inclusion of Pxd to the conventional chemotherapeutic agent(s) could be an effective therapeutic strategy for CRC.

Could circRNA be a new biomarker for pre-eclampsia?

Pre-eclampsia is a devastating complication of pregnancy which is characterized by hypertension and proteinuria in pregnant women. Pre-eclampsia is important as it is the leading cause of death. Moreover, untreated pre-eclampsia might lead to other lethal complications, for both fetus and mother. Pre-eclampsia can also affect the quality of life in affected women. Despite a large number of risk factors for pre-eclampsia, these risk factors are able to detect just 30% of women who are susceptible to pre-eclampsia. Heterogeneous manifestations of pre-eclampsia necessitate the discovery of potential biomarkers required for its early detection. Circular RNAs (circRNAs) are a type of RNA which are more abundant, specific, and highly organized compared with other types of RNA. Accordingly, circRNAs have been suggested as one of the potential biomarkers for different diseases. Recently, researchers have shown interest in the effects of circRNAs in pre-eclampsia, although the current evidence is limited. The majority of obstetricians are probably not aware of circRNAs as a useful biomarker. Here, we aimed to summarize recent supporting evidence and assess the mechanisms by which circRNAs are involved in pre-eclampsia.

Extracellular vesicles in host-pathogen interactions and immune regulation - exosomes as emerging actors in the immunological theater of pregnancy

This review correlates and summarizes the role of the maternal-fetal interface in the immune tolerance of the fetus and the processes that lead to infection avoidance, emphasizing the participation of exosomes and other extracellular vesicles in both situations. Exosomes are released into the extracellular medium by several cell types and are excellent carriers of biomolecules. Host-derived exosomes and the transport of pathogen-derived molecules by exosomes impact infections in different ways. The interactions of exosomes with the maternal immune system are pivotal to a favorable gestational outcome. In this review, we highlight the potential role of exosomes in the establishment of an adequate milieu that enables embryo implantation and discuss the participation of exosomes released at the maternal-fetal interface during the establishment of an immune-privileged compartment for fetal development. The placenta is a component where important strategies are used to minimize the risk of infection. To present a contrast, we also discuss possible mechanisms used by pathogens to cross the maternal-fetal interface. We review the processes, mechanisms, and potential consequences of dysregulation in all of the abovementioned phenomena. Basic information about exosomes and their roles in viral immune evasion is also presented. The interactions between extracellular vesicles and bacteria, fungi, parasites and proteinaceous infectious agents are addressed. The discovery of the placental microbiota and the implications of this new microbiota are also discussed, and current proposals that explain fetal/placental colonization by both pathogenic and commensal microbes are addressed. The comprehension of such interactions will help us to understand the immune dynamics of human pregnancy and the mechanisms of immune evasion used by different pathogens.

The relationship between Fas and Fas ligand gene polymorphism and preeclampsia risk

Preeclampsia is an idiopathic multisystem disorder with partial genetic and immunological etiology. Several studies investigated the association between various single-nucleotide polymorphisms (SNPs) in Fas and Fas ligand (FasL) genes and the risk of preeclampsia. However, they achieved inconsistent results. Therefore, we conducted a meta-analysis by systematically searching the Cochrane Library, PubMed and Embase databases and assessed this association by calculating pooled odds ratios with 95% confidence interval to reach a more trustworthy conclusion. Subgroup analyses by genotype methods and source of controls (SOC) were also conducted. Seven citations containing nine studies were included for four SNPs (Fas -670 A/G, FasL 124A/G, FasL -844C/T, Fas -1377 G/A) in this meta-analysis. Our data suggested the G allele and genotype GG of the Fas -670 A/G polymorphism, GG genotype of the FasL 124A/G polymorphism, and TT genotype of the FasL -844C/T polymorphism increased the risk of preeclampsia. Stratification analyses by genotype methods and SOC also indicated that Fas -670 A/G polymorphism was related to increased risk for preeclampsia. In conclusion, Fas and FasL gene polymorphisms play important roles in the development of preeclampsia. Further well-designed studies in other races are needed to confirm the findings of this meta-analysis.

Effects of apigenin on the expression levels of B-cell lymphoma-2, Fas and Fas ligand in renal ischemia-reperfusion injury in rats

The aim of the present study was to investigate the effect and possible mechanism of apigenin on renal ischemia-reperfusion (I/R) injury in rats, as well as in in vitro experiments. In total, 36 rats were subjected to 45 min of renal ischemia, with or without treatment prior to ischemia with different concentrations of apigenin (2, 10 and 50 mg/kg) administered intravenously. All rats were sacrificed at 24 h after I/R injury. The serum creatinine (Cr) and blood urea nitrogen (BUN) levels were analyzed, and histological examination was conducted. In addition, the expression levels of B-cell lymphoma 2 (Bcl-2) and Fas/Fas ligand (FasL) were detected by immunohistochemistry, reverse transcription-quantitative polymerase chain reaction and western blot analysis. For in vitro experiments, the NRK-52E cell line was employed. The viability, apoptosis and expression levels of Fas, FasL and Bcl-2 were examined in the culture of NRK-52E cells following the I/R. The results indicated that apigenin significantly decreased the levels of serum Cr and BUN induced by renal I/R, demonstrating an improvement in renal function. The histological evidence of renal damage associated with I/R was also mitigated by apigenin in vivo. Furthermore, apigenin increased the cell viability and decreased cell apoptosis in the culture of NRK52E after I/R in vitro. Compared with the I/R group, the expression of Bcl-2 was upregulated and the expression levels of Fas and FasL were downregulated by apigenin at the mRNA and protein levels in vivo and in vitro. In conclusion, apigenin appeared to increase the expression of Bcl-2 and reduce Fas/FasL expression in renal I/R injury, providing evident protection against renal I/R injury in rats.

Meiotic wave adds extra asymmetry to the development of female chicken gonads

Development of female gonads in the chicken is asymmetric. This asymmetry affects gene expression, morphology, and germ cell development; consequently only the left ovary develops into a functional organ, whereas the right ovary remains vestigial. In males, on the other hand, both gonads develop into functional testes. Here, we revisited the development of asymmetric traits in female (and male) chicken gonads between Hamburger Hamilton stage 16 (HH16) and hatching. At HH16, primordial germ cells migrated preferentially to the left gonad, accumulating in the left coelomic hinge between the gut mesentery and developing gonad in both males and females. Using the meiotic markers SYCP3 and phosphorylated H2AFX, we identified a previously undescribed, pronounced asymmetryc meiotic progression in the germ cells located in the central, lateral, and extreme cortical regions of the left female gonad from HH38 until hatching. Moreover, we observed that--in contrast to the current view--medullary germ cells are not apoptotic, but remain arrested in pre-leptotene until hatching. In addition to the systematic analysis of the asymmetric distribution of germ cells in female chicken gonads, we propose an updated model suggesting that the localization of germ cells--in the left or right gonad; in the cortex or medulla of the left gonad; and in the central part or the extremities of the left cortex--has direct consequences for their development and participation in adult reproduction.

Effects of maternal diabetes on trophoblast cells

Diabetes mellitus (DM) is a health condition characterized by hyperglycemia over a prolonged period. There are three main types of DM: DM type 1 (DM1), DM2 and gestational DM (GDM). Maternal diabetes, which includes the occurrence of DM1 and DM2 during pregnancy or GDM, increases the occurrence of gesttional complications and adverse fetal outcomes. The hyperglycemic intrauterine environment affects not only the fetus but also the placental development and function in humans and experimental rodents. The underlying mechanisms are still unclear, but some evidence indicates alterations in trophoblast proliferation, apoptosis and cell cycle control in diabetes. A proper coordination of trophoblast proliferation, differentiation and invasion is required for placental development. Initially, increased expression of proliferative markers in junctional and labyrinth zones of rat placentas and villous cytotrophoblast, syncytiotrophoblast, stromal cells and fetal endothelial cells in human placentas is reported among diabetics. Moreover, reduced apoptotic index and expression of some apoptotic genes are described in placentas of GDM women. In addition, cell cycle regulators including cyclins and cyclin-dependent kinase inhibitors seem to be affected by the hyperglycemic environment. More studies are necessary to check the balance between proliferation, apoptosis and differentiation in trophoblast cells during maternal diabetes.

Expression and regulation of avian cathepsin L in the oviduct during molting

Cathepsins (CTSs) are peptidases that have biological roles in degrading extracellular matrix, catabolism of intracellular proteins, and processing of pro-hormones. Of these, cathepsin L (CTSL) is closely associated with morphological changes in reproductive organs required for proper function in mammals, including humans and mice, but little is known about CTSL in avian species. In the present study, the expression of CTSL was investigated in the oviduct of hens during regression and recrudescence in response to molting. Our results revealed that expression of CTSL mRNA increased (P<0.001) when the oviduct underwent regression during the molting period in hens. In situ hybridization and immunohistochemial analyses detected CTSL mRNA and protein predominantly in the luminal (LE) and glandular epithelia (GE) during regression of the oviduct, but not during regeneration of the oviduct. Expression of CTSL decreased in the oviduct of chicks treated with diethylstilbestrol (DES, a synthetic estrogen agonist). Furthermore, we discovered four miRNAs including miR-23b, miR-551, miR-1464 and miR-1803 that regulate expression of the CTSL gene at the post-transcriptional level, which suggests that CTSL mRNA can be regulated by specific miRNAs via 3'-UTR in chickens. Results of the present research suggest that estrogen regulates expression of CTSL during regression of the oviduct during molting and that down-regulation of CTSL is likely a prerequisite for the normal regeneration of oviductal tissues following molting in laying hens.

Enhanced stimulation of anti-ovarian cancer CD8(+) T cells by dendritic cells loaded with nanoparticle encapsulated tumor antigen

PROBLEM

Dendritic cell (DC)-based cancer therapies are favored approaches to stimulate anti-tumor T-cell responses. Unfortunately, tolerance to tumor antigens is difficult to overcome. Biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) are effective reagents in the delivery of drugs and tumor-associated antigens (TAA). In this study, we assessed the capacity of a PLGA NP-based delivery system to augment CD8 T-cell responses to ovarian cancer TAA.

METHOD OF STUDY

Human DC were generated from blood monocytes by conventional in vitro differentiation and loaded with either soluble tumor lysate or NP/lysate conjugates (NPL). These antigen-loaded DC were then used to stimulate autologous CD8(+) T cells. Cytokine production and activation markers were evaluated in the CD8(+) T cells.

RESULTS

DC loading with NPL increased cytokine production by stimulated CD8 T cells and induced T-cell expression of cell surface co-stimulatory molecules, typical of anti-tumor immune responses. In contrast, delivery of naked tumor lysate antigens preferentially induced a T-cell profile characteristic of tolerization/exhaustion.

CONCLUSION

These findings indicate that delivery of TAA in NP enables DC to efficiently activate anti-tumor CD8(+) T cells. PLGA NP encapsulation of tumor-derived lysate protein antigens is an encouraging new preparative methodology for DC-based vaccination meriting clinical testing.

Modulation of macrophage inflammatory profile in pregnant nonobese diabetic (NOD) mice

During normal early pregnancy circulating monocytes are recruited to the maternal-placental interface where they differentiate to macrophages expressing different functional phenotypes for the maintenance of tissue homeostasis. Pregnancy in the nonobese diabetic (NOD) mouse model presents some pathological features in the pre-diabetic stage. The aim of this work was to analyze the functional profile of peritoneal macrophages faced with inflammatory and phagocytic stimuli in early pregnant pre-diabetic NOD mice and their modulation by vasoactive intestinal peptide (VIP). Pregnant NOD mouse macrophages showed no basal NFκB activation, lower IL-12 and nitrites production compared with the macrophages from non-pregnant NOD mice. Their pro-inflammatory aberrant response to LPS and apoptotic cell challenge was reduced and VIP inhibited macrophage residual deleterious responses to apoptotic cells. A functional phenotype switch in macrophages during pregnancy in NOD mice and a promoting effect of VIP towards this regulatory phenotype would be in line with the central role of macrophages in the maternal-placental dialogue.

Cancers take their Toll--the function and regulation of Toll-like receptors in cancer cells

Cancer could be deemed as an abnormal and uncontrolled tissue repair process. Therefore, it would not be surprising that factors that function in the tissue repair process, such as cytokines, chemokines, growth factors and Toll-like receptor (TLR) ligands, as well as growth signals for compensatory proliferation, would also be key factors in regulating and enhancing cancer progression. The TLR pathways, which play a critical role in tissue repair, are also key regulators in cancer progression as well as chemoresistance. TLRs serve as cell surface sensors that can initiate pathways leading to proliferation and chemoresistance; as well as mediators that are able to regulate the infiltrating immune cells to provide further support for cancer progression.

CD 95 mediated apoptosis in embryogenesis: implication in tooth development

INTRODUCTION

Understanding of apoptotic mechanisms involved in tissue shaping is of particular interest because of possible targeted modulation of the development of organ structures such as teeth. Research of CD 95 mediated apoptosis has been focused particularly on cell death in the immune system and related disorders. However, CD 95 mediated apoptosis is also involved in embryogenesis of many organs as the kidney, the lung, the intestine and tissue networks such as the nervous system.

DESIGN

Narrative review.

RESULTS

This review briefly summarizes the current knowledge of CD 95 mediated apoptosis in embryogenesis with possible implication in tooth development. CD 95 receptor and CD 95 ligand are found at early stages of tooth development. The data suggest some positive correlations with dental apoptosis distribution, particularly in the primary enamel knot where apoptosis occurs during elimination of this structure. CD 95 deficient (lpr) adult mouse tooth phenotype, however, did not show any alterations in final tooth pattern and morphology.

CONCLUSION

To date studies of apoptotic machinery during tooth development show spatial localization of many of the components together with precise and localized timing of cell death. There is still much to be learned about the regulation and importance of apoptosis in tooth development. Nevertheless, the involvement of apoptotic regulatory mechanisms interplaying with other molecules participates to the cellular cross-talk in developing tissues, which opens possible targeted modulations as suggested, e.g. for future molecular dentistry.

Galectin-1: biphasic growth regulation of Leydig tumor cells

Galectin-1 (Gal-1) is a widely expressed beta-galactoside-binding protein that exerts pleiotropic biological functions. To gain insight into the potential role of Gal-1 as a novel modulator of Leydig cells, we investigated its effect on the growth and death of MA-10 tumor Leydig cells. In this study, we identified cytoplasmic Gal-1 expression in these tumor cells by cytofluorometry. DNA fragmentation, caspase-3, -8, and -9 activation, loss of mitochondrial membrane potential (DeltaPsim), cytochrome c (Cyt c) release, and FasL expression suggested that relatively high concentrations of exogenously added recombinant Gal-1 (rGal-1) induced apoptosis by the mitochondrial and death receptor pathways. These pathways were independently activated, as the presence of the inhibitor of caspase-8 or -9 only partially prevented Gal-1-effect. On the contrary, low concentrations of Gal-1 significantly promoted cell proliferation, without inducing cell death. Importantly, the presence of the disaccharide lactose prevented Gal-1 effects, suggesting the involvement of the carbohydrate recognition domain (CRD). This study provides strong evidence that Gal-1 is a novel biphasic regulator of Leydig tumor cell number, suggesting a novel role for Gal-1 in the reproductive physiopathology.

Soluble Fas receptor and soluble Fas ligand in the serum of women with uterine tumors

It is commonly accepted that apoptosis plays an important role in the death of normal and neoplastic cells. Related proteins and their receptors on cell surfaces regulate apoptosis. One of the best-characterized systems is the Fas-Fas ligand system. The aim of the study was to examine the concentrations of soluble Fas receptor (sFas) and the soluble ligand for the Fas receptor (sFasL) in serum of women with uterine tumors. The study included 42 women with uterine tumors. As a normal control, sera were obtained from 20 healthy female volunteers. The concentrations of sFas and sFasL in serum were measured by enzyme-linked immunosorbent assay ELISA. Significant increases of the mean value of sFas and sFasL were found in the serum of women with uterine tumor compared to the control group (p < 0.0001). The mean levels of these parameters increased in consecutive stages of the clinical extent of the uterine cancer (I-III). The lowest concentration was observed in women with stage I and the highest in women with stage III of clinical extent according to FIGO. Apoptosis that appears to occur in the cancerous cells of malignant uterine tumors is associated with high levels of sFas and sFasL in serum.

The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy

Apoptosis is important for normal placental development, but it may also be involved in the pathophysiology of pregnancy-related diseases. Normal placental development is dependent upon the differentiation and invasion of the trophoblast, the main cellular component of the placenta. Trophoblast apoptosis increases in normal placentas as gestation proceeds, and a greater incidence of trophoblast apoptosis has been observed in pregnancies complicated by preeclampsia or intrauterine growth retardation (IUGR). In response to different stimuli, apoptosis may be initiated extrinsically by the death receptor pathway or intrinsically by the mitochondrial pathway. The central executioners of apoptosis are the caspases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By inhibiting caspase activation, several endogenous inhibitors, including flice-like inhibitory proteins (FLIPs), inhibitors of apoptosis (IAPs), and antiapoptotic Bcl-2 family members, can prevent further propagation of the death signal. Macrophages present at the maternal-fetal interface may also contribute to trophoblast survival by removing apoptotic cells and producing cytokines and growth factors, which influence the progression of the apoptotic cascade. This review focuses on the role of apoptosis in trophoblast development and differentiation, the molecular mechanisms by which normal trophoblast apoptosis can occur, and how it is regulated to prevent excessive trophoblast apoptosis and possible pregnancy complications.

Estrogens up-regulate the Fas/FasL apoptotic pathway in lactotropes

The Fas/FasL system provides the major apoptotic mechanism for many cell types, participating in cell turnover in hormone-dependent tissues. In the present study, we localized both Fas and FasL in anterior pituitary cells, mainly in lactotropes and somatotropes. The percentage of anterior pituitary cells showing immunoreactivity for Fas or FasL was higher in cells from rats killed in proestrus than in diestrus. Also, the proportion of pituitary cells from ovariectomized (OVX) rats expressing Fas or FasL increased in the presence of 17beta-estradiol (10(-9) M). This steroid increased the percentage of lactotropes with immunoreactivity for Fas or FasL and the percentage of somatotropes expressing Fas. Activation of Fas by an agonist anti-Fas antibody (Mab-Fas) decreased the vi-ability-3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT assay)-of anterior pituitary cells from OVX rats cultured in the presence of 17beta-estradiol. Also, membrane-bound FasL decreased cell viability-[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay (MTS assay)-only when anterior pituitary cells from OVX rats were incubated with 17beta-estradiol. Moreover, FasL increased the percentage of hypodiploid anterior pituitary cells (flow cytometry). Mab-Fas increased the percentage of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive pituitary cells and lactotropes from OVX rats only when cells were incubated in the presence of 17beta-estradiol. Also, Mab-Fas triggered apoptosis of anterior pituitary cells from rats killed at proestrus but not at diestrus. Our results show that 17beta-estradiol up-regulates the expression of the Fas/FasL system in anterior pituitary cells and increases Fas-induced apoptosis in lactotropes, suggesting that Fas-induced apoptosis could be involved in the pituitary cell renewal during the estrous cycle.

Detection of Fas ligand in the bovine oviduct

Presence of a Fas-Fas ligand (FasL) system defines the immune-privileged status of certain tissues such as placenta. This study examined the fluids and tissue(s) of the bovine oviduct, where both spermatozoa and early embryos escape elimination by the female immune system, for the presence and the distribution of Fas and FasL, which might provide an explanation for the immune-privileged site of this organ. In the present study, the immunolocalisation of FasL and Fas, as well as the gene expression of FasL, were determined in the uterotubal junction (UTJ), isthmic (I) and ampullar (A) segments of the oviduct during oestrus and the luteal phase of the oestrous cycle. The degree of apoptosis of oviductal epithelium was examined by the TUNEL method. Oviductal fluid (ODF), collected chronically via indwelling catheters from the I or A segments during both non-luteal and luteal phases of the cycle, was analysed for the presence of FasL. The Fas immunostaining was scattered along the epithelium of all regions of the oviduct and cycle stages investigated, whereas FasL immunolabelling was more conspicuous in oestrous samples. This staining disappeared during the luteal phase, which was particularly evident in the sperm reservoir (UTJ and I). There were fewer TUNEL-positive cells than Fas- or FasL-positive cells in the oviductal epithelium, suggesting that tubal Fas and FasL are not directly involved in epithelial apoptosis. Western blot analyses detected FasL in ODF collected from both I and A, most conspicuously as a 24-27kDa band but also at a 40-45kDa band level. FasL mRNA was expressed in the epithelial cells from the sperm reservoir and A during both non-luteal and luteal phases. However, the level of expression differed significantly between segments during the luteal phase. The results provide novel evidence that the Fas-FasL system is present in the bovine oviduct and could be involved in mediating survival of spermatozoa and early embryos.

Pre-eclampsia

Pre-eclampsia is a major cause of maternal mortality (15-20% in developed countries) and morbidities (acute and long-term), perinatal deaths, preterm birth, and intrauterine growth restriction. Key findings support a causal or pathogenetic model of superficial placentation driven by immune maladaptation, with subsequently reduced concentrations of angiogenic growth factors and increased placental debris in the maternal circulation resulting in a (mainly hypertensive) maternal inflammatory response. The final phenotype, maternal pre-eclamptic syndrome, is further modulated by pre-existing maternal cardiovascular or metabolic fitness. Currently, women at risk are identified on the basis of epidemiological and clinical risk factors, but the diagnostic criteria of pre-eclampsia remain unclear, with no known biomarkers. Treatment is still prenatal care, timely diagnosis, proper management, and timely delivery. Many interventions to lengthen pregnancy (eg, treatment for mild hypertension, plasma-volume expansion, and corticosteroid use) have a poor evidence base. We review findings on the diagnosis, risk factors, and pathogenesis of pre-eclampsia and the present status of its prediction, prevention, and management.

Macrophages and apoptotic cell clearance during pregnancy

BACKGROUND

During implantation, apoptosis is critical for the appropriate tissue remodeling of the maternal decidua and invasion of the developing embryo, yet the regulation of apoptosis is also imperative for a successful pregnancy. The quick and effective removal of apoptotic cells by tissue macrophages represents an essential process, which prevents the release of self-antigens, and in the case of pregnancy, paternal alloantigens.

METHODS OF STUDY

Recent studies have shown that the process of apoptotic cell clearance is not a neutral event, but rather an active one that induces macrophage production of anti-inflammatory cytokines and survival factors. Apoptotic cell clearance is, therefore, necessary for the resolution of inflammatory conditions, which during pregnancy could have lethal consequences.

CONCLUSIONS

The function of the maternal immune system during implantation and throughout pregnancy is, therefore, an important area of investigation. This review will discuss the role of decidual macrophages in apoptotic cell clearance during pregnancy.

The Fas/Fas ligand system and cancer: immune privilege and apoptosis

The Fas/FasL system has been suggested to play an important role in the establishment of immune privilege status for tumors by inducing Fas-mediated apoptosis in tumor-specific lymphocytes. However, the role of cell-surface expressed FasL in tumor cell protection has recently become controversial. Our laboratory has focused on the study of the role of the Fas/FasL system in the normal tissue remodeling of the female reproductive tract and in immune-privileged organs. Our studies have demonstrated a connection between sex hormones and the regulation of the Fas/FasL pathway in immune and reproductive cells. More recently, we have investigated the resistance of tumor cells to Fas-mediated apoptosis. We have also characterized a new form of FasL, different from the classical membranal form, which is secreted by ovarian cancer cells. In this review we describe the main techniques used in these studies.

Potential role of macrophages as immunoregulators of pregnancy

The role of the maternal immune system during pregnancy has focused mainly on the aspect of immune tolerance to the invading trophoblast and, therefore, fetus. While this is a critical aspect of reproductive immunology, it is also important to consider the function of the maternal immune system in the promotion of implantation and maintenance of pregnancy. Apoptosis or cell death is not the final stage in tissue development. The quick and effective removal of apoptotic cells by tissue macrophages represents a vital process preventing "leak" of self-antigens and promoting the production of proliferative/survival factors. One of the key requirements of apoptotic cell clearance is the resolution of inflammatory conditions, which, as in the case of pregnancy, may have lethal consequences. This review will focus on decidual macrophages and their role on apoptosis and cell clearance during pregnancy.

Targeted therapy for epithelial ovarian cancer: Current status and future prospects

Despite advances in surgery and chemotherapy, less than 20% of patients with stage III or IV ovarian cancer survive long-term. In the past, cytotoxic regimens have been developed empirically, combining active agents at maximally tolerated doses, often without a clear rationale for their interaction. Advances in understanding the biology of ovarian cancer have identified multiple molecular targets that differ in normal and malignant cells. Targets include cell cycle regulators, growth factor receptors, signal transduction pathways, molecules that confer drug resistance, and angiogenic mechanisms. A number of targeted agents have entered clinical trials. Small molecular weight inhibitors, monoclonal antibodies, and antisense and gene therapy are all being evaluated alone and in combination with cytotoxic drugs. In contrast to earlier studies, the impact of each agent on the designated target can be assessed and agents can be matched to the genotype and phenotype of malignant and normal cells. In the long run, this should facilitate individualization of more effective, less toxic therapy for women with ovarian cancer.

Phenoxodiol--an isoflavone analog--induces apoptosis in chemoresistant ovarian cancer cells

Interference with the innate apoptotic activity is a hallmark of neoplastic transformation and tumor formation. In this study we characterize the cytotoxic effect of phenoxodiol, a synthetic anticancer drug analog of genestein, and demonstrate the mechanism of action by which phenoxodiol affects the components of the Fas apoptotic pathway on ovarian cancer cells. Primary ovarian cancer cells, isolated from ascitic fluids of ovarian cancer patients, resistant to conventional chemotherapy, undergo apoptosis following phenoxodiol treatment. This effect is dependent upon the activation of the caspase system, inhibiting XIAP, an inhibitor of apoptosis, and disrupting FLICE inhibitory protein (FLIP) expression through the Akt signal transduction pathway. We suggest that phenoxodiol is an efficient inducer of cell death in ovarian cancer cells and sensitizes the cancer cells to Fas-mediated apoptosis. We identified FLIP and XIAP signalling pathways as key factors regulating the survival of ovarian cancer cells. These findings demonstrate a novel nontoxic drug that controls FLIP/XIAP function and has the potential to eliminate tumor cells through Fas-mediated apoptosis.