The metabolic characteristic of decidual immune cells and their unique properties in pregnancy loss.

Maternal tolerance to semi- or fully allograft conceptus is a prerequisite for the maintenance of pregnancy. Once this homeostasis is disrupted, it may result in pregnancy loss. As a potential approach to prevent pregnancy loss, targeting decidual immune cells (DICs) at the maternal-fetal interface has been suggested. Although the phenotypic features and functions of DIC have been extensively profiled, the regulatory pathways for this unique immunological adaption have yet to be elucidated. In recent years, a pivotal mechanism has been highlighted in the area of immunometabolism, by which the changes in intracellular metabolic pathways in DIC and interaction with the adjacent metabolites in the microenvironment can alter their phenotypes and function. More inspiringly, the manipulation of metabolic profiling in DIC provides a novel avenue for the prevention and treatment of pregnancy loss. Herein, this review highlights the major metabolic programs (specifically, glycolysis, ATP-adenosine metabolism, lysophosphatidic acid metabolism, and amino acid metabolism) in multiple immune cells (including decidual NK cells, macrophages, and T cells) and their integrations with the metabolic microenvironment in normal pregnancy. Importantly, this perspective may help to provide a potential therapeutic strategy for reducing pregnancy loss via targeting this interplay.

Accumulation of γδT cells in the decidua is promoted by RANKL which upregulates ICAM-1 via NF-κB.

In brief: The mechanism underlying the accumulation of γδT cells in the decidua, which helps maintain maternal-fetal immunotolerance in early pregnancy, is unknown. This study reveals that DSC-derived RANKL upregulates ICAM-1 expression via the NF-κB pathway to enable γδT cell accumulation in the early decidua. Abstract: Decidual γδT (dγδT) cells help maintain maternal-fetal immunotolerance in early pregnancy. However, the mechanism underlying the accumulation of γδT cells in the decidua is unknown. Previous work showed that RANKL upregulated intercellular adhesion molecule 1 (ICAM-1) in decidual stromal cells (DSCs), and Rankl knockout mice had limited dγδT cell populations. In this study, we measured the expression levels of RANKL/RANK and ICAM-1 in DSCs, in addition to the integrins of ICAM-1 on dγδT cells, and the number of dγδT cells from patients with recurrent spontaneous abortion (RSA) and normal pregnant women in the first trimester. RSA patients showed significantly decreased RANKL/RANK and ICAM-1/CD11a signaling in decidua, and a decreased percentage of dγδT cells, which was positively correlated with DSC-derived RANKL and ICAM-1. Next, an in vitro adhesion experiment showed that the enhanced attraction of human DSCs to dγδT cells after RANKL overexpression was almost completely aborted by anti-ICAM-1. Furthermore, Rankl knockout mice showed a significant reduction in NF-κB activity compared with wild-type controls. Finally, we applied a selective NF-κB inhibitor named PDTC to validate the role of NF-κB in RANKL-mediated ICAM-1 upregulation. Taken together, our data show that DSC-derived RANKL upregulates ICAM-1 expression via the NF-κB pathway to enable γδT cell accumulation in the early decidua. A reduction in RANKL/ICAM-1 signaling in DSCs may result in insufficient accumulation of γδT cells in decidua and, in turn, RSA.

Extracellular succinate derived from ectopic milieu drives adhesion and implantation growth of ectopic endometrial stromal cells via the SUCNR1 signal in endometriosis.

BACKGROUND: As a dual-function metabolite, succinate has emerged in cell function and plays a key signaling role in linking mitochondrial function to other cellular functions. Succinate accumulation in the cytoplasm is commonly associated with hypoxia in the microenvironment and immune cell activation. Extracellular succinate released into the microenvironment is considered an inflammatory alarm that can be sensed by its membrane receptor SUCNR1, which boosts proinflammatory responses and acts akin to classical hormones and cytokines. Succinate plays an important role in the development of inflammatory diseases. Whether succinate facilitates the progression of endometriosis (EMs), characterized by chronic inflammation and peritoneal adhesion, is worth exploring. OBJECTIVE: We mimicked the ectopic milieu in vitro and in vivo to evaluate the main source and potential role of succinate in endometriosis. We assessed the molecular and functional effects of succinate on macrophages and peritoneal mesothelial cells in peritoneal cavity. The effect of succinate/SUCNR1 signaling on ectopic endometrial stromal cells (ESCs) was further explored in this study. METHODS: In this study, we used targeted organic acid metabolomics analysis and in vitro assays to assess the potential accumulation of succinate in the peritoneal fluid of EMs patients. We examined its correlation with disease severity, Visual Analogue Scale, and the Endometriosis Fertility Index. Flow cytometry, enzyme linked immunosorbent assay, western blot assay, quantitative real-time PCR, and other molecular biology techniques were used to explore the potential mechanisms. RESULTS: By mimicking the ectopic milieu, we constructed an in vitro co-culture system and found that M1 polarized macrophages and that the peritoneal mesothelial cell line (HMrSV5) mainly released succinate into their microenvironment and activated the succinate receptor (SUCNR1) signal, which further polarized the macrophages and significantly enhanced the invasive survival of ESCs, and the adhesion to the peritoneum. We further investigated the pathological effects of extracellular succinate in vivo using a xenograft mouse models of endometriosis. CONCLUSIONS: Succinate-SUCNR1 signaling facilitates the creation of inflammatory cells and plays a vital role in EMs progression and peritoneal adhesion. Our work on the molecular mechanisms underlying succinate accumulation and function will help elucidate the phenotypic mysteries of pain and infertility in EMs. Video Abstract.

The IL-33-ST2 axis plays a vital role in endometriosis via promoting epithelial-mesenchymal transition by phosphorylating ß-catenin.

OBJECTIVES: Interleukin 33 (IL-33) is a crucial inflammatory factor that functions as an alarm signal in endometriosis (EMs). Epithelial-mesenchymal transition (EMT), a process related to inflammatory signals, intracellular reactive oxygen species (ROS) production, and lipid peroxidation, have been proposed as potential mechanisms that contribute to the development and progression of EMs. IL-33 is highly upregulated in the ectopic milieu. Moreover, ectopic endometrial cells constitutively express interleukin-33 receptor ST2 (IL-33R). However, the role of IL-33/ST2 in the EMT of EMs remains largely unknown. In this study, we aimed to mechanistically determine the role of IL-33/ST2 in EMs-associated fibrosis. MATERIALS AND METHODS: We established a non-lethal oxidative stress model to explore the conditions that trigger IL-33 induction. We performed α-smooth muscle actin (α-SMA) protein detection, cell counting kit-8 (CCK-8) assays, and scratch assays to analyze the impact of IL-33 on primary endometrial stromal cells (ESCs) proliferation and invasion. Clinical samples from patients with or without EMs were subjected to immunohistochemical (IHC) and and immunofluorescence(IF) staining to assess the clinical relevance of IL-33 receptor ST2 and EMT-related proteins. Furthermore, we used the ectopic human endometrial epithelial cell line 12Z and normal human epithelial cell line EEC to evaluate the effects of IL-33 on Wnt/ß-catenin signaling. The effect of IL-33 on EMT-associated fibrosis was validated in vivo by intraperitoneal injections of IL-33 and antiST2. RESULTS: We observed that ectopic milieu, characterized by ROS, TGF-ß1, and high level of estrogen, triggers the secretion of IL-33 from ectopic ESCs. Ectopic endometrial lesions exhibited higher level of fibrotic characteristics and ST2 expression than that in the normal endometrium. Exogenous recombinant human (rhIL-33) enhanced ESC migration and survival. Similarly, 12Z cells displayed a higher degree of EMT characteristics with elevated expression of CCN4 and Fra-1, downstream target genes of the WNT/ß-catenin pathway, than that observed in EECs. Conversely, blocking IL-33 with neutralizing antibodies, knocking down ST2 or ß-catenin with siRNA, and ß-catenin dephosphorylation abolished its effects on EMT promotion. In vivo validation demonstrated that IL-33 significantly promotes EMs-related fibrosis through the activation of Wnt/ß-catenin signaling. CONCLUSION: Our data strongly support the vital role of the IL-33/ST2 pathway in EMs-associated fibrosis and emphasize the importance of the EMT in the pathophysiology of fibrosis. Targeting the IL-33/ST2/Wnt/ß-catenin axis may hold promise as a feasible therapeutic approach for controlling fibrosis in EMs.

Novel Insights into Prokineticin 1 Role in Pregnancy-related Diseases.

Prokineticin 1 (PROK1) is a secreted protein involved in a range of physiological activities such as cell proliferation, migration, angiogenesis, and neuronal cell proliferation. Emerging evidences show that PROK1/PROK receptors (PROKRs) are expressed by trophoblasts, and decidual stroma cells at the maternal-fetal interface. PROK1 plays a critical role in successful pregnancy establishment by regulating the decidualization, implantation and placental development. Dysregulation of prokineticin signaling has been described in certain pathological states associated with pregnancy, including pre-eclampsia, recurrent miscarriage and fetal growth restriction. In this review, the expression and pleiotropic roles of PROK1 under physiological and pathological pregnancy conditions are discussed.

Chitosan alleviates ovarian aging by enhancing macrophage phagocyte-mediated tissue homeostasis.

BACKGROUND: Age-related changes in the ovarian microenvironment are linked to impaired fertility in women. Macrophages play important roles in ovarian tissue homeostasis and immune surveillance. However, the impact of aging on ovarian macrophage function and ovarian homeostasis remains poorly understood. METHODS: Senescence-associated beta-galactosidase staining, immunohistochemistry, and TUNEL staining were used to assess senescence and apoptosis, respectively. Flow cytometry was employed to evaluate mitochondrial membrane potential (MMP) and apoptosis in granulosa cells lines (KGN), and macrophages phagocytosis. After a 2-month treatment with low molecular weight Chitosan (LMWC), ovarian tissues from mice were collected for comprehensive analysis. RESULTS: Compared with the liver and uterus, the ovary displayed accelerated aging in an age-dependent manner, which was accompanied by elevated levels of inflammatory factors and apoptotic cells, and impaired macrophage phagocytic activity. The aged KGN cells exhibited elevated reactive oxygen species (ROS) and apoptotic levels alongside decreased MMP. H2O2-induced aging macrophages showed reduced phagocytosis function. Moreover, there were excessive aging macrophages with impaired phagocytosis in the follicular fluid of patients with diminished ovarian reserve (DOR). Notably, LMWC administration alleviated ovarian aging by enhancing macrophage phagocytosis and promoting tissue homeostasis. CONCLUSIONS: Aging ovarian is characterized by an accumulation of aging and apoptotic granulosa cells, an inflammatory response and macrophage phagocytosis dysfunction. In turn, impaired phagocytosis of macrophage contributes to insufficient clearance of aging and apoptotic granulosa cells and the increased risk of DOR. Additionally, LMWC emerges as a potential therapeutic strategy for age-related ovarian dysfunction.

An Estrogen-NK Cells Regulatory Axis in Endometriosis, Related Infertility, and Miscarriage.

Endometriosis is a common estrogen-dependent condition that impacts 8-10% of women in their reproductive age, resulting in notable pain, morbidity, and infertility. Despite extensive research endeavors, the precise cause of endometriosis remains elusive, and the mechanisms contributing to its associated infertility are still not well comprehended. Natural killer (NK) cells, vital innate immune cells crucial for successful pregnancy, have been investigated for their potential involvement in the pathogenesis of endometriosis. Prior research has mainly concentrated on the diminished cytotoxicity of NK cells in endometrial fragments that evade the uterus. Interestingly, accumulating evidence suggests that NK cells play multifaceted roles in regulating the biology of endometrial stromal cells (ESCs), promoting local immune tolerance, influencing endometrial receptivity, oocyte development, and embryo implantation, thereby contributing to infertility and miscarriage in patients with endometriosis. In this comprehensive review, our goal is to summarize the current literature and provide an overview of the implications of NK cells in endometriosis, especially concerning infertility and pregnancy loss, under the influence of estrogen.

Association of serum 25-hydroxyvitamin D levels with all-cause and cause-specific mortality among postmenopausal females: results from NHANES.

BACKGROUND: Vitamin D deficiency is common among the population, but its relationship with mortality of postmenopausal females is unclear. The aim of this study is to explore the association between serum 25-Hydroxyvitamin D (25(OH)D) and all-cause and cause-specific mortality among postmenopausal women in the United States. METHODS: 6812 participants of postmenopausal females from the National Health and Nutrition Examination Survey (2001-2018) were included in this study. The mortality status of the follow-up was ascertained by linkage to National Death Index (NDI) records through 31 December 2019. We used cox proportional hazards models to estimate the association of serum 25(OH)D concentrations and mortality of postmenopausal females. RESULTS: The mean level of serum 25(OH)D was 72.57 ± 29.93 nmol/L, and 65.34% had insufficient vitamin D. In postmenopausal females, low serum 25(OH)D concentrations were significantly associated with higher levels of glycohemoglobin, glucose, and lower levels of HDL. During follow-up, 1448 all-cause deaths occurred, including 393 cardiovascular disease (CVD)-related deaths and 263 cancer deaths. After multivariate adjustment, higher serum 25(OH)D levels were significantly related with lower all-cause and CVD mortality. In addition, serum 25(OH)D presented a L-shaped relationship with all-cause mortality, while appeared a U-shaped with CVD mortality, and the cut-off value is 73.89 nmol/L and 46.75 nmol/L respectively. CONCLUSIONS: Low serum 25(OH)D levels are associated with the higher risk of all-cause and CVD mortality in postmenopausal females. These findings provide new ideas and targets for the health management of postmenopausal women.

An abnormal LPA/LPAR1-NHE1 axis leads to the autophagy deficiency of trophoblast cells in recurrent spontaneous abortion.

In brief: Autophagy is important for trophoblast cells at the maternal-fetal interface during early pregnancy. This study suggests that trophoblast cells can promote the autophagy under a regulation of the LPA/LPAR 1-NHE1 axis. Abstract: The autophagy of trophoblasts is necessary for developing and maintaining a healthy pregnancy. Autophagy dysfunction in trophoblast cells is linked to recurrent spontaneous abortion (RSA). However, the mechanism underlying trophoblast autophagy is unknown. In this study, we investigated the expression of autophagy-related genes in both normal and RSA villi. We also examined the production of LPA and LPAR1 in trophoblast cells during early pregnancy. We found that the activation of the LPA-LPAR1 axis triggered the autophagy of trophoblast cells and increased the expression of NHE1. Inhibition of NHE1 suppressed the autophagy in trophoblast cells and we confirmed that NHE1 regulates LPA production in trophoblast cells. Additionally, we found decreased expression of autophagy-related genes and LPAR1 in villi from RSA patients. These observations indicate that the LPA/LPAR1-NHE1 axis regulates the autophagy of trophoblast cells during pregnancy. Insufficient autophagy and poor expression of LPAR1 in trophoblast cells may result in the dysfunction of the trophoblasts and an increased risk of spontaneous abortion. Overall, our research elucidated that a positive LPA/LPAR1-NHE1 axis can promote the autophagy of trophoblast cells and the abnormal axis leads to the autophagy deficiency of trophoblast cells in recurrent spontaneous abortion.

Hypoxia-mediated chemotaxis and residence of macrophage in decidua by secreting VEGFA and CCL2 during normal pregnancy.

In brief: Hypoxia is vital for the establishment of the maternal-fetal interface during early pregnancy. This study shows that decidual macrophages (dMφ) could be recruited and reside in decidua under the regulation of hypoxia/VEGFA-CCL2 axis. Abstract: Infiltration and residence of decidual macrophages (dMφ) are of great significance to pregnancy maintenance for their role in angiogenesis, placental development, and inducing immune tolerance. Besides, hypoxia has now been acknowledged as an important biological event at maternal-fetal interface in the first trimester. However, whether and how hypoxia regulates biofunctions of dMφ remain elusive. Herein, we observed increased expression of C-C motif chemokine ligand 2 (CCL2) and residence of macrophages in decidua compared to secretory-phase endometrium. Moreover, hypoxia treatment on stromal cells improved the migration and adhesion of dMφ. Mechanistically, these effects might be mediated by upregulated CCL2 and adhesion molecules (especially ICAM2 and ICAM5) on stromal cells in the presence of endogenous vascular endothelial growth factor-A (VEGFA) in hypoxia. These findings were also verified by recombinant VEGFA and indirect coculture, indicating that the interaction between stromal cells and dMφ in hypoxia condition may facilitate dMφ recruitment and residence. In conclusion, VEGFA derived from a hypoxic environment may manipulate CCL2/CCR2 and adhesion molecules to enhance the interactions between dMφ and stromal cells and thus contribute to the enrichment of macrophages in decidua early during normal pregnancy.

Bone marrow stromal cell-derived exosomal circular RNA improves diabetic foot ulcer wound healing by activating the nuclear factor erythroid 2-related factor 2 pathway and inhibiting ferroptosis.

BACKGROUND: Diabetic foot ulcer (DFU) remains a serious chronic diabetic complication that can lead to disability. CircRNA-itchy E3 ubiquitin protein ligase (circ-ITCH) was observed to be down-regulated in diabetic retinopathy and diabetic nephropathy, and overexpression of circ-ITCH could inhibit the processes of these diseases. However, the detailed physiological and pathological functions of circ-ITCH in wound healing of DFU remain undetermined. METHODS: Exosomes derived from bone marrow stromal cells (BMSCs) were isolated and identified. Cell viability and angiogenesis of human umbilical vein endothelial cells (HUVECs) were evaluated by cell counting kit-8 (CCK-8) and tube formation assays, respectively. The interplays of circ-ITCH, TATA-Box-binding protein associated factor 15 (TAF15) and nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA were analysed by RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) combined immunofluorescent staining and RNA pull-down assays. qRT-PCR, western blot or immunohistochemistry (IHC) were used to measure the expression of circ-ITCH, TAF15, Nrf2, vascular endothelial growth factor (VEGFR) and ferroptosis-related makers. The mice DFU model was established to verify the in vitro results. RESULTS: Circ-ITCH was down-regulated in in vitro and in vivo models of DFU. Deferoxamine (DFO), an iron chelating agent, improved the viability and angiogenic ability of high glucose (HG)-treated HUVECs. Overexpression of circ-ITCH or co-cultured with exosomal circ-ITCH from BMSCs could alleviate HG-induced ferroptosis and improve the angiogenesis ability of HUVECs. Circ-ITCH in HUVECs recruited TAF15 protein to stabilize Nrf2 mRNA, thus activating the Nrf2 signalling pathway and suppressing ferroptosis. Exosomal circ-ITCH from BMSCs also accelerated the wound healing process by inhibiting ferroptosis in the DFU mice in a time-dependent manner. CONCLUSION: Exosomal circ-ITCH from BMSCs inhibited ferroptosis and improved the angiogenesis of HUVECs through activation of the Nrf2 signalling pathway by recruiting TAF15 protein, ultimately accelerating the wound healing process in DFU.

IL-27 deficiency inhibits proliferation and invasion of trophoblasts via the SFRP2/Wnt/ß-catenin pathway in fetal growth restriction.

Background: Fetal growth restriction (FGR) is characterized by restricted fetal growth and dysregulated placental development. The etiology and pathogenesis still remain elusive. IL-27 shows multiple roles in regulating various biological processes, however, how IL-27 involves in placentation in FGR pregnancy hasn't been demonstrated. Methods: The levels of IL-27 and IL-27RA in FGR and normal placentae were determined by immunohistochemistry, western blot and RT-PCR. HTR-8/SVneo cells and Il27ra-/- murine models have been adopted to evaluate the effects of IL-27 on the bio-functions of trophoblast cells. GO enrichment and GSEA analysis were performed to explore the underlying mechanism. Findings: IL-27 and IL-27RA was lowly expressed in FGR placentae and administration of IL-27 on HTR-8/SVneo could promote its proliferation, migration and invasion. Comparing with wildtypes, Il27ra-/- embryos were smaller and lighter, and the placentae from which were poorly developed. In mechanism, the molecules of canonical Wnt/ß-catenin pathway (CCND1, CMYC, SOX9) were downregulated in Il27ra-/- placentae. In contrast, the expression of SFRP2 (negative regulator of Wnt) was increased. Overexpression of SFRP2 in vitro could impair trophoblast migration and invasion capacity. Interpretation: IL-27/IL-27RA negatively regulates SFRP2 to activate Wnt/ß-catenin, and thus promotes migration and invasion of trophoblasts during pregnancy. However, IL-27 deficiency may contribute to the development of FGR by restricting the Wnt activity.

Association of Early Pregnancy Free and Total Triiodothyronine With the Subsequent Risk of Gestational Diabetes Mellitus.

OBJECTIVE: To estimate the association of free triiodothyronine (FT3) and total triiodothyronine (TT3) in early pregnancy and subsequent gestational diabetes mellitus (GDM) risk and define appropriate TT3 thresholds for GDM screening. METHODS: This investigation is a hospital-based cohort study of pregnant women submitted to a universal thyroid function test before 24 weeks of gestation. GDM was diagnosed according to a 75-g oral glucose tolerance test. The association of maternal high FT3 and TT3 levels in early pregnancy with the risk of GDM was estimated using logistic regression. The potential nonlinear association was probed by the restricted cubic spline curve method. RESULTS: A total of 27 184 pregnant women and 3073 GDM cases were included in the analysis. FT3 and TT3 were associated with an increased subsequent risk of GDM in a nonlinear fashion. The adjusted odds ratios were 1.59 (95% confidence interval, 1.50-1.68) and 2.80 (95% confidence interval, 2.46-3.18) for FT3 and TT3 continuous levels, respectively. Associations were strong in euthyroid women, showed heterogeneity in women with mild thyroid dysfunction, and lacked in patients with overt hypothyroidism and hyperthyroidism. The TT3 thresholds of 1.5 and 2.0 ng/mL between 7 and 12 weeks of gestation and 1.6 and 2.1 ng/mL for 13 to 23 weeks of gestation effectively distinguished the subsequent risk of GDM. CONCLUSION: The increased FT3 and TT3 levels in early pregnancy were associated with a subsequent higher risk of GDM. These findings provide measures for early detection and potential prevention of GDM.

Maternal expectations of fetal gender and risk of postpartum depression.

BACKGROUND: Female offspring was associated with a high risk of postpartum depression (PPD) during the one-child policy period in China. However, little is known about the association between maternal expectations on fetal gender and the risk of PPD in the context of the new two children policy implemented in 2016. METHODS: We conducted a hospital-based cohort study of women with singleton pregnancies between 2017 and 2018 (n = 991) to address this concern. Logistic regression was run to estimate the association between unexpected fetal gender and the risk of PPD. RESULTS: A total of 127 women (12.8%) were diagnosed with PPD. Compared with women who achieved fetal gender expectations, the odds ratio (OR) for PPD among those who had an unexpected fetal gender was 2.44 (95% confidence interval (CI): 1.30-4.58) (in the backward method logistic regression model) and 2.25 (95% CI: 1.21-4.18) (in the forward method model), respectively. The disparity of the association was significant among primiparous and pluriparous women (OR, 2.52, 95% CI: 1.32-4.84, P = 0.005 vs. OR, 0.91, 95% CI: 0.09-8.75, P = 0.932). Fetal gender expectations accounted for about 15% of the risk of PPD in the structural equation models. CONCLUSIONS: These results indicated that unexpected fetal gender was associated with an increased risk of PPD among Chinese primiparous women.

Maternal traditional Chinese medicine exposure and risk of congenital malformations: a multicenter prospective cohort study.

INTRODUCTION: The potential teratogenic risk of traditional Chinese medicine (TCM) is of widespread concern; however, related evidence is largely absent in humans. This study aimed to compare the prevalence of congenital malformations between pregnant women with and without TCM exposure. MATERIAL AND METHODS: This was a multicenter prospective cohort study of 17 713 women who participated in a survey on periconceptional TCM exposure. Primary outcome was congenital malformations diagnosed from a survey conducted on the day 42 after delivery. RESULTS: A total of 16 751 pregnant women with 273 congenital malformations were included in the analysis. Fetuses exposed to TCM had an increased risk of congenital malformations compared to those without exposure (odds ratio [OR] 2.10; 95% confidence interval [CI] 1.09-4.02) after controlling for potential confounders. There were significant associations with congenital malformations in women with early pregnant exposure (OR 2.04, 95% CI 1.00-4.20) and for those who received ≥2 TCM formulas (OR 5.84, 95% CI 1.44-23.65). Pre-pregnancy TCM exposure was significantly associated with an increased risk of congenital heart defects (OR 12.69; 95% CI 3.01-53.51). CONCLUSIONS: Periconceptional TCM exposure is associated with an increased risk of congenital malformation. This effect was cumulative and sensitive to periconceptional age. Therefore, TCM deserves more attention and should be used cautiously for pregnant women and those trying to become pregnant.

An imbalance of the IL-33/ST2-AXL-efferocytosis axis induces pregnancy loss through metabolic reprogramming of decidual macrophages.

During embryo implantation, apoptosis is inevitable. These apoptotic cells (ACs) are removed by efferocytosis, in which macrophages are filled with a metabolite load nearly equal to the phagocyte itself. A timely question pertains to the relationship between efferocytosis-related metabolism and the immune behavior of decidual macrophages (dMΦs) and its effect on pregnancy outcome. Here, we report positive feedback of IL-33/ST2-AXL-efferocytosis leading to pregnancy failure through metabolic reprogramming of dMΦs. We compared the serum levels of IL-33 and sST2, along with IL-33 and ST2, efferocytosis and metabolism of dMΦs, from patients with normal pregnancies and unexplained recurrent pregnancy loss (RPL). We revealed disruption of the IL-33/ST2 axis, increased apoptotic cells and elevated efferocytosis of dMΦs from patients with RPL. The dMΦs that engulfed many apoptotic cells secreted more sST2 and less TGF-ß, which polarized dMΦs toward the M1 phenotype. Moreover, the elevated sST2 biased the efferocytosis-related metabolism of RPL dMΦs toward oxidative phosphorylation and exacerbated the disruption of the IL-33/ST2 signaling pathway. Metabolic disorders also lead to dysfunction of efferocytosis, resulting in more uncleared apoptotic cells and secondary necrosis. We also screened the efferocytotic molecule AXL regulated by IL-33/ST2. This positive feedback axis of IL-33/ST2-AXL-efferocytosis led to pregnancy failure. IL-33 knockout mice demonstrated poor pregnancy outcomes, and exogenous supplementation with mouse IL-33 reduced the embryo losses. These findings highlight a new etiological mechanism whereby dMΦs leverage immunometabolism for homeostasis of the microenvironment at the maternal-fetal interface.

An active glutamine/α-ketoglutarate/HIF-1α axis prevents pregnancy loss by triggering decidual IGF1+GDF15+NK cell differentiation.

Deficiency of decidual NK (dNK) cell number and function has been widely regarded as an important cause of spontaneous abortion. However, the metabolic mechanism underlying the crosstalk between dNK cells and embryonic trophoblasts during early pregnancy remains largely unknown. Here, we observed that enriched glutamine and activated glutaminolysis in dNK cells contribute to trophoblast invasion and embryo growth by insulin-like growth factor-1 (IGF-1) and growth differentiation factor-15 (GDF-15) secretion. Mechanistically, these processes are dependent on the downregulation of EGLN1-HIF-1α mediated by α-ketoglutarate (α-KG). Blocking glutaminolysis with the GLS inhibitor BPTES or the glutamate dehydrogenase inhibitor EGCG leads to early embryo implantation failure, spontaneous abortion and/or fetal growth restriction in pregnant mice with impaired trophoblast invasion. Additionally, α-KG supplementation significantly alleviated pregnancy loss mediated by defective glutaminolysis in vivo, suggesting that inactivated glutamine/α-ketoglutarate metabolism in dNK cells impaired trophoblast invasion and induced pregnancy loss.

An IGF1-expressing endometrial stromal cell population is associated with human decidualization.

BACKGROUND: Decidualization refers to the process of transformation of endometrial stromal fibroblast cells into specialized decidual stromal cells that provide a nutritive and immunoprivileged matrix essential for blastocyst implantation and placental development. Deficiencies in decidualization are associated with a variety of pregnancy disorders, including female infertility, recurrent implantation failure (RIF), and miscarriages. Despite the increasing number of genes reportedly associated with endometrial receptivity and decidualization, the cellular and molecular mechanisms triggering and underlying decidualization remain largely unknown. Here, we analyze single-cell transcriptional profiles of endometrial cells during the window of implantation and decidual cells of early pregnancy, to gains insights on the process of decidualization. RESULTS: We observed a unique IGF1+ stromal cell that may initiate decidualization by single-cell RNA sequencing. We found the IL1B+ stromal cells promote gland degeneration and decidua hemostasis. We defined a subset of NK cells for accelerating decidualization and extravillous trophoblast (EVT) invasion by AREG-IGF1 and AREG-CSF1 regulatory axe. Further analysis indicates that EVT promote decidualization possibly by multiply pathways. Additionally, a systematic repository of cell-cell communication for decidualization was developed. An aberrant ratio conversion of IGF1+ stromal cells to IGF1R+ stromal cells is observed in unexplained RIF patients. CONCLUSIONS: Overall, a unique subpopulation of IGF1+ stromal cell is involved in initiating decidualization. Our observations provide deeper insights into the molecular and cellular characterizations of decidualization, and a platform for further development of evaluation of decidualization degree and treatment for decidualization disorder-related diseases.

Single-Frame Infrared Image Non-Uniformity Correction Based on Wavelet Domain Noise Separation.

In the context of non-uniformity correction (NUC) within infrared imaging systems, current methods frequently concentrate solely on high-frequency stripe non-uniformity noise, neglecting the impact of global low-frequency non-uniformity on image quality, and are susceptible to ghosting artifacts from neighboring frames. In response to such challenges, we propose a method for the correction of non-uniformity in single-frame infrared images based on noise separation in the wavelet domain. More specifically, we commence by decomposing the noisy image into distinct frequency components through wavelet transformation. Subsequently, we employ a clustering algorithm to extract high-frequency noise from the vertical components within the wavelet domain, concurrently employing a method of surface fitting to capture low-frequency noise from the approximate components within the wavelet domain. Ultimately, the restored image is obtained by subtracting the combined noise components. The experimental results demonstrate that the proposed method, when applied to simulated noisy images, achieves the optimal levels among seven compared methods in terms of MSE, PSNR, and SSIM metrics. After correction on three sets of real-world test image sequences, the average non-uniformity index is reduced by 75.54%. Moreover, our method does not impose significant computational overhead in the elimination of superimposed noise, which is particularly suitable for applications necessitating stringent requirements in both image quality and processing speed.

Emerging Roles of Lysophosphatidic Acid in Macrophages and Inflammatory Diseases.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that regulates physiological and pathological processes in numerous cell biological functions, including cell migration, apoptosis, and proliferation. Macrophages are found in most human tissues and have multiple physiological and pathological functions. There is growing evidence that LPA signaling plays a significant role in the physiological function of macrophages and accelerates the development of diseases caused by macrophage dysfunction and inflammation, such as inflammation-related diseases, cancer, atherosclerosis, and fibrosis. In this review, we summarize the roles of LPA in macrophages, analyze numerous macrophage- and inflammation-associated diseases triggered by LPA, and discuss LPA-targeting therapeutic strategies.