The Relationship between Cadmium Exposure and Mortality in Postmenopausal Females: A Cohort Study of 2001-2018 NHANES.

Cadmium is one of the most harmful elements to human health, and the health of postmenopausal females is an important public health issue. However, the correlation between exposure to cadmium and the survival status of postmenopausal women is currently not fully clear. This research intended to explore the correlation between cadmium exposure and mortality among postmenopausal females using a representative sample of the population in the U.S. We drew upon the data of the National Health and Nutrition Examination Survey (2001-2018). Cox's proportional hazards models and a restricted cubic spline regression (RCS) model were utilized to analyze the correlation between blood and urine cadmium and the mortality of postmenopausal women. Stratified analyses also were conducted to identify the highest risk factor of mortality for the participants. The mean concentration of blood cadmium was 0.59 µg/L, and the mean concentration of urine cadmium was 0.73 µg/g creatinine. Higher cadmium concentrations in blood and urine were significantly related to an increase in all-cause mortality for postmenopausal females after adjustment for multivariate covariates. Furthermore, there was a linear positive correlation between urine cadmium concentrations and cancer mortality, while there was no correlation between blood cadmium and cancer death. The correlation between cadmium concentrations and all-cause mortality is stronger in older, more overweight women with a history of hypertension or smoking. We propose that cadmium remains an important risk factor of all-cause and cancer mortality among postmenopausal females in the U.S. Further decreases in cadmium exposure in the population can promote the health of postmenopausal women and prolong their lifespan.

The role of CXC chemokine ligand 16 in physiological and pathological pregnancies.

The survival and development of a semi-allogeneic fetus during pregnancy require the involvement of a series of cytokines and immune cells. Chemokines are a type of special cytokine those were originally described as having a role in leukocyte trafficking. CXC chemokine ligand (CXCL) 16 is a member of the chemokine family, and CXC chemokine receptor (CXCR) 6 is its sole receptor. Emerging evidence has shown that CXCL16/CXCR6 is expressed at the maternal-fetal interface, by cell types that include trophoblast cells, decidual stroma cells, and decidual immune cells (eg, monocytes, γδT cells, and natural killer T (NKT) cells). The regulation of expression of CXCL16 is quite complex, and this process involves a multitude of factors. CXCL16 exerts a critical role in the establishment of a successful pregnancy through a series of molecular interactions at the maternal-fetal interface. However, an abnormal expression of CXCL16 is associated with certain pathological states associated with pregnancy, including recurrent miscarriage, pre-eclampsia, and gestational diabetes mellitus (GDM). In the present review, the expression and pleiotropic roles of CXCL16 under conditions of physiological and pathological pregnancy are systematically discussed.

Trophoblast-Derived CXCL16 Decreased Granzyme B Production of Decidual γδ T Cells and Promoted Bcl-xL Expression of Trophoblasts.

BACKGROUND: Decidual γδ T cells are known to regulate the function of trophoblasts at the maternal-fetal interface; however, little is known about the molecular mechanisms of cross talk between trophoblast cells and decidual γδ T cells. METHODS: Expression of chemokine C-X-C motif ligand 6 (CXCL16) and its receptor CXCR6 was evaluated in first-trimester human villus and decidual tissues by immunohistochemistry. γδ T cells were isolated from first-trimester human deciduae and cocultured with JEG3 trophoblast cells. Cell proliferation and apoptosis-related molecules, together with cytotoxicity factor and cytokine production, were measured by flow cytometry analysis. RESULTS: Expression of CXCL16 and CXCR6 was reduced at the maternal-fetal interface in patients who experienced unexplained recurrent spontaneous abortion as compared to healthy pregnancy women. With the administration of pregnancy-related hormones or coculture with JEG3 cells, CXCR6 expression was upregulated on decidual γδ T cells. CXCL16 derived from JEG3 cells caused a decrease in granzyme B production of decidual γδ T cells. In addition, decidual γδ T cells educated by JEG3-derived CXCL16 upregulated the expression of Bcl-xL in JEG3 cells. CONCLUSION: This study suggested that the CXCL16/CXCR6 axis may contribute to maintaining normal pregnancy by reducing the secretion of cytotoxic factor granzyme B of decidual γδ T cells and promoting the expression of antiapoptotic marker Bcl-xL of trophoblasts.

IL-25 promotes Th2 bias by upregulating IL-4 and IL-10 expression of decidual γδT cells in early pregnancy.

Decidual immune cells (DICs), consisting of both innate and adaptive immune cells, have a pivotal role in maintaining immune tolerance for normal pregnancy. Our previous study demonstrated that interleukin (IL)-25 stimulates the proliferation of decidual stromal cells (DSCs) in an autocrine manner. However, the role of IL-25 in functional regulation of DICs is largely unknown. Flow cytometry was used to analyze the expression of IL-25 and its receptor (IL-17RB) in DICs, and the effect of IL-25 on the expression of Ki-67, IL-4, IL-10, interferon (IFN)-γ and transforming growth factor (TGF)-ß in decidual γδT cells. In addition, ELISA assays were performed to detect the secretion of IL-10 and TGF-ß in decidual γδT cells. The present findings indicated that decidual CD56 bright CD16-natural killer (NK) cells, natural killer T (NKT) cells, regulatory T (Treg) cells, CD3+ T cells, macrophages and γδT cells co-expressed IL-25 and IL-17RB, particularly γδT cells. Recombinant human (rh) IL-25 protein upregulated the expression of Ki-67, IL-4, and IL-10, but downregulated the expression of IFN-γ in γδT cells; however, anti-human IL-25 or IL-17RB neutralizing antibody reversed these effects. These data suggest that IL-25 may promote IL-10 production by γδT cells as well as the proliferation of γδT cells, and possibly forms a positive feedback loop to maintain a T helper 2 cell bias at the maternal-fetal interface and further contributes to the maintenance of successful pregnancy.

IL­33 restricts invasion and adhesion of trophoblast cell line JEG3 by downregulation of integrin α4ß1 and CD62L.

Interleukin-33 (IL-33) promotes migration of cancer cells through downregulating the expression of E-cadherin. Previous studies have demonstrated that IL­33 stimulates the proliferation of trophoblasts. However, the effect of IL­33 on the adhesion and invasion of trophoblasts has not been investigated in detail. In the present study, the expression of IL­33 and its receptor, IL­1 receptor­like 1 (ST2), was examined in villi from women during early pregnancy using immunohistochemistry. ST2 expression on human trophoblast and choriocarcinoma cell lines JAR, BeWo, JEG3 and HTR8 was confirmed by flow cytometry (FCM) assay. The effect of recombinant human IL­33 (rhIL­33) on adhesion, invasion and associated molecules was analyzed by cell adhesion, Matrigel invasion and FCM assays. The current study identified that human trophoblasts expressed IL­33 and ST2. RhIL­33 inhibited trophoblast invasion and adhesion, and decreased adhesion and invasion­associated molecules such as integrin α4ß1 and CD62L. Therefore, these results suggest that IL­33 may serve an important role in limiting invasion and implantation of trophoblasts by adhesion and invasion­associated molecules, contributing to the formation of the placenta and maintenance of normal pregnancy during early pregnancy.

PCSK6 regulated by LH inhibits the apoptosis of human granulosa cells via activin A and TGFß2.

Mammalian proprotein convertases (PCs) play an important role in folliculogenesis, as they proteolytically activate a variety of substrates such as the transforming growth factor beta (TGFß) superfamily. PC subtilism/kexin 6 (PCSK6) is a member of the PC family and is ubiquitously expressed and implicated in many physiological and pathological processes. However, in human granulosa cells, the expression of the PC family members, their hormonal regulation, and the function of PCs are not clear. In this study, we found that PCSK6 is the most highly expressed PC family member in granulosa cells. LH increased PCSK6 mRNA level and PCSK6 played an anti-apoptosis function in KGN cells. Knockdown of PCSK6 not only increased the secretion of activin A and TGFß2 but also decreased the secretion of follistatin, estrogen, and the mRNA levels of FSH receptor (FSHR) and P450AROM (CYP19A1). We also found that, in the KGN human granulosa cell line, TGFß2 and activin A could promote the apoptosis of KGN cells and LH could regulate the follistatin level. These data indicate that PCSK6, which is regulated by LH, is highly expressed in human primary granulosa cells of pre-ovulatory follicles and plays important roles in regulating a series of downstream molecules and apoptosis of KGN cells.

Interleukin-25 induced by human chorionic gonadotropin promotes the proliferation of decidual stromal cells by activation of JNK and AKT signal pathways.

OBJECTIVE: To clarify the role and mechanism of interleukin (IL)-25 in regulating the biological functions of decidual stromal cells (DSCs) in human early pregnancy. DESIGN: Laboratory study of the effect of IL-25 induced by hCG on the proliferation of DSCs. SETTING: Research laboratories. PATIENT(S): Women aged 23-47 years with normal pregnancy and abortion. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Signal transduction from IL-25. RESULT(S): Here we show that DSCs coexpress IL-25/IL-17RB. Human chorionic gonadotropin promotes the expression of IL-25/IL-17RB. In contrast to anti-human IL-25 neutralizing antibody, recombinant human IL-25 (rhIL-25) significantly stimulates the proliferation of DSCs in dosage- and time-dependent manners. RhIL-25 promotes the phosphorylation of AKT, extracellular-signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinases (JNK), and nuclear factor κB in DSCs. Interestingly, blocking JNK or AKT signal with inhibitors down-regulates the stimulatory effect on DSC proliferation induced by rhIL-25. In addition, the results of Western blot show that the expression of IL-25/IL-17RB in DSCs from normal pregnancy was higher than that from abortion. CONCLUSION(S): Our results have revealed that hCG derived of trophoblasts up-regulates the expression of IL-25/IL-17RB in DSCs and that IL-25 further stimulates the proliferation of DSCs through activating JNK and AKT signals, which finally contributes to the establishment and maintenance of physiological pregnancy.

Thymic stromal lymphopoietin suppresses the apoptosis of decidual gamma-delta T cells via regulation of the signal transduction and activation of transcription 3/caspase-3 signaling pathway.

PROBLEM: To investigate whether thymic stromal lymphopoietin (TSLP) regulates the apoptosis of decidual γδ T cells and to elucidate the mechanism. METHOD OF STUDY: Primary human decidual γδ T cells were treated with TSLP only or TSLP combined with different signaling inhibitors (STAT3, STAT5, AKT, and ERK). The levels of signal transduction and activation of transcription 3 (STAT3) tyrosine phosphorylation and caspase3 expression were determined using Western blot analysis, and the apoptosis of decidual γδ T cells was analyzed by flow cytometry. RESULTS: The proportions of γδ T cells in the peripheral circulation and in decidual CD3(+) cell population in women with normal pregnancy were higher than the proportions of γδ T cells in either non-pregnant control or miscarriage. Decidual γδ T cells co-expressed the TSLP receptors (TSLPR) and IL-7Rα, and the expression of TSLPR in decidual γδ T cells was higher than that in decidual CD8(+) and CD4(+) T cells. Treatment with TSLP significantly suppressed the apoptosis of decidual γδ T cells and enhanced STAT3 phosphorylation. Moreover, STAT3, and not other inhibitors, completely abrogated the anti-apoptotic effect and expression of caspase3 in decidual γδ T cells induced by recombinant human TSLP. CONCLUSION: These results suggest that TSLP may down-regulate caspase3 expression through activation of the STAT3 pathway, thereby suppressing the apoptosis of decidual γδ T cells.

Thymic stromal lymphopoietin downregulates NME1 expression and promotes invasion in human trophoblasts via the activation of STAT3 signaling pathway.

Our previous study has demonstrated that TSLP induces the invasion of human trophoblasts and plays a role in embryo implantation. The present study is undertaken to explore the mechanism by which TSLP modulates trophoblast invasion. It was revealed that TSLP treatment significantly downregulated NME1 and TIMP1 expression in both human trophoblasts and JEG-3 cells. The stimulatory effect of TSLP on trophoblast invasion was partially inhibited by either STAT3 inhibitor or STAT5 inhibitor. The downregulation of NME1 expression by TSLP was completely abrogated by STAT3 inhibitor. TIMP1 expression was attenuated by NME1 siRNA interference and enhanced by NME1 overexpression in JEG-3 cells. TSLP-stimulated increase in trophoblast invasion was partially attenuated by NME1 overexpression. Our data suggest that TSLP might downregulate NME1 expression via STAT3 signaling pathway, affecting TIMP1 expression in influencing trophoblast invasion. Our studies suggest that further studies on TSLP as a potential therapeutic for recurrent spontaneous abortion are warranted.

The decidual gamma-delta T cells up-regulate the biological functions of trophoblasts via IL-10 secretion in early human pregnancy.

The functions of decidual γδT cells in early human pregnancy are not fully understood. The present study was undertaken to characterize the action of decidual γδT cells, and analyze their regulatory roles in proliferation and invasion of trophoblasts in early human pregnancy. It was revealed that decidual γδT cells were a CD4(-) and CD8(-) subset whose numbers increased significantly in either the decidua or peripheral blood. The main cytokines synthesized in decidual γδT cells in decreasing concentration were; IL-10>TGF-ß>TNF-α≥IFN-γ, with little IL-2 or IL-4 being produced. Decidual γδT cells promoted trophoblast proliferation and invasion, and suppressed trophoblast apoptosis through IL-10 secretion in co-culture. These results suggest that γδT cells in human decidua might play an important role in the Th2 bias at maternal-fetal interface and in the development and progression of the placenta, which is beneficial to maternal immunotolerance toward the fetus in early human pregnancy.

The costimulatory signal upregulation is associated with Th1 bias at the maternal-fetal interface in human miscarriage.

PROBLEM To evaluate whether the association of the costimulatory signal regulation with T helper 1/T helper 2 (Th1/Th2) bias at maternal-fetal interface in human pregnancy loss. METHOD OF STUDY The expression of CD80 and CD86 in decidual tissues and CD28 and cytotoxic T-lymphocyte antigen-4 (CTLA-4) in the decidual T cells was compared between normal early pregnancy and miscarriage by qPCR and Western blot. The cytokine production in decidual T cells was performed by flow cytometry. The correlation of costimulatory molecule expression with Th1/Th2 cytokines was analyzed. RESULTS The CD80 mRNA and protein expression showed no significant difference between normal pregnancy and miscarriage. An increase in the expression of CD28 and CD86 was accompanied by a decrease in the expression of CTLA-4 in miscarriage in comparison with the early pregnancy. The higher expression of interleukin (IL)-2 and interferon-γ (IFN-γ), and lower expression of IL-4 and IL-10 in the decidual T cells were present in miscarriage. A correlation analysis showed a significant positive correlation of CD86 and CD28 expression with the Th1 cytokine production (IL-2 and IFN-γ), a significant negative correlation of CTLA-4 expression with the Th1 cytokine production. CONCLUSION The upregualtion of costimulatory signals on T cells might form an abnormal immune microenvironment, a shift to Th1 responses, at maternal-fetal interface, which leads to human miscarriage.

CXCL12 controls over-invasion of trophoblasts via upregulating CD82 expression in DSCs at maternal-fetal interface of human early pregnancy in a paracrine manner.

Tetraspanin CD82 has been identified as a potential contributor to controlling trophoblast invasiveness in human first-trimester pregnancy. However, it is unclear how the regulation of CD82 expression at maternal-fetal interface. The present study is to investigate the effect of the trophoblast-derived CXCL12 on CD82 expression in decidual stromal cells (DSCs) that in turn controls trophoblast cell invasiveness. In-cell Western was used to evaluate the expression of CD82 in DSCs. A co-culture model was established to investigate the reciprocal interaction between trophoblasts and DSCs via CXCL12/CXCR4 and CD82 expression. We found that both anti-CXCL12 and anti-CXCR4 neutralizing antibody can eliminate increase of CD82 expression in DSCs induced by the trophoblasts supernatant. Moreover, the invasiveness of trophoblasts pre-treated with anti-CXCR4 neutralizing antibody was significantly decreased. Interestingly, when DSCs were pre-treated with anti-CXCR4 neutralizing antibody, the trophoblasts invasiveness in the co-culture was enhanced, and thus anti-CXCR4 neutralizing antibody can reverse the decrease of trophoblasts invasiveness induced by CD82. The trophoblast cell-derived CXCL12 does not only increase the invasiveness in an autocrine manner, but also control the over-invasion of trophoblasts through promoting CD82 expression in DSCs in a paracrine manner, which maintains a physiological balance of human trophoblasts invasiveness via the cross-talk between trophoblasts and DSCs.

Regulation of costimulatory signal in maternal-fetal immune tolerance.

A pregnancy is associated with modifications in the immune status of the mother, but the mechanisms are not well understood. Several observations have indicated that CD28/CTLA-4 and B7-1/B7-2 are involved in the maternal-fetal immune regulation. This review aims to recapitulate our current knowledge concerning the role of CD28/CTLA-4 and B7-1/B7-2 in maternal-fetal immune regulation. Several studies suggest that up-regulation of B7-2 and/or CD28 and/or down-regulation of CTLA-4 are correlated with the occurrence of pregnancy loss. Therefore, an accurate expression of costimulatory molecules at the maternal-fetal interface may ensure that the decidual cells do not elicit a 'danger' signal to the maternal immune system, perhaps instead contributing to the establishment of immune tolerance in vivo. It is showed that costimulation blockade with anti-B7 mAbs results in altered allogeneic T-cell response and overcomes increased maternal rejection to the fetus, which improves fetus growth in the abortion-prone system. These findings suggest that the anti-B7-treated T cells not only function as potent suppresser cells but also exert immunoregulatory effect on the maternal T cells. This procedure might be potentially useful to immunotherapy for human recurrent spontaneous abortion.