Placental Trophoblast Specific Overexpression of Chemerin Induces Preeclampsia-like Symptoms

Raised levels of chemerin in women with preeclampsia: A meta-analysis

Chemerin is a multifunctional adipokine associated with systemic inflammation, angiogenesis, and oxidative stress. Emerging evidence suggests a potential link between chemerin and the pathogenesis of preeclampsia (PE). In this systematic review and meta-analysis, we aimed to evaluate the serum chemerin levels in women with PE. A systematic search was conducted across Medline, Web of Science, and Embase databases from inception until April 15, 2023, to identify studies comparing serum chemerin levels in pregnant women with and without PE. A random-effects model was employed to pool the results, accounting for heterogeneity. Thirteen datasets from 10 observational studies, encompassing 832 women with PE and 1298 healthy pregnant women, were analyzed. The pooled findings indicated a statistically significant elevation in serum chemerin levels in women with PE compared to controls (mean difference [MD] = 89.56 ng/mL, 95% confidence interval [CI] 62.14 - 116.98; P < 0.001; I2 = 87%). The subgroup analysis revealed consistent findings across studies that measured chemerin levels before or after the diagnosis of PE, studies that did or did not match the body mass index (BMI), and studies with varying quality scores (P values for subgroup differences were all > 0.05). Compared to controls, women with severe PE exhibited a significantly greater increase in serum chemerin levels than those with mild PE (P value for subgroup difference = 0.007). Additionally, meta-regression analysis results suggested that the mean BMI of the included pregnant women might positively modify the difference in circulating chemerin levels between women with and without PE (coefficient = 8.92; P = 0.045). In conclusion, this meta-analysis suggests a positive correlation between elevated serum chemerin levels and PE diagnosis in comparison to pregnant women without the condition.

Statins Prevent the Deleterious Consequences of Placental Chemerin Upregulation in Preeclampsia

BACKGROUND

Chemerin, an inflammatory adipokine, is upregulated in preeclampsia, and its placental overexpression results in preeclampsia-like symptoms in mice. Statins may lower chemerin.

METHODS

Chemerin was determined in a prospective cohort study in women suspected of preeclampsia and evaluated as a predictor versus the sFlt-1 (soluble fms-like tyrosine kinase-1)/PlGF (placental growth factor) ratio. Chemerin release was studied in perfused placentas and placental explants with or without the statins pravastatin and fluvastatin. We also addressed statin placental passage and the effects of chemerin in chorionic plate arteries.

RESULTS

Serum chemerin was elevated in women with preeclampsia, and its addition to a predictive model yielded significant effects on top of the sFlt-1/PlGF ratio to predict preeclampsia and its fetal complications. Perfused placentas and explants of preeclamptic women released more chemerin and sFlt-1 and less PlGF than those of healthy pregnant women. Statins reversed this. Both statins entered the fetal compartment, and the fetal/maternal concentration ratio of pravastatin was twice that of fluvastatin. Chemerin constricted plate arteries, and this was blocked by a chemerin receptor antagonist and pravastatin. Chemerin did not potentiate endothelin-1 in chorionic plate arteries. In explants, statins upregulated low-density lipoprotein receptor expression, which relies on the same transcription factor as chemerin, and NO release.

CONCLUSIONS

Chemerin is a biomarker for preeclampsia, and statins both prevent its placental upregulation and effects, in an NO and low-density lipoprotein receptor-dependent manner. Combined with their capacity to improve the sFlt-1/PlGF ratio, this offers an attractive mechanism by which statins may prevent or treat preeclampsia.

Physical exercise for a healthy pregnancy: the role of placentokines and exerkines

Complications such as diabetes and preeclampsia can occur during pregnancy. Moderate-intensity exercise can prevent such complications by releasing placentokines and exerkines, such as apelin, adiponectin, leptin, irisin, and chemerin. Exercise and apelin increase thermogenesis and glucose uptake in pregnancy by activating AMPK, PI3K, PGC-1α, AKT1, UCP3, and sarcolipin. Exercise increases apelin levels to reduce preeclampsia symptoms by increasing eNOS, NO, placental growth factor (PlGF), and VEGF and decreasing levels of fms-like tyrosine kinase 1 (sFlt-1), soluble endoglin (sEng), and oxidative stress. A negative relationship has been reported between plasma leptin and VO2peak/kg and VO2peak in women with gestational diabetes. In active women, decreases in leptin levels reduce the risk of preeclampsia by ~ 40%. Higher adiponectin levels are associated with greater physical activity and lead to increased insulin sensitivity. Increased adiponectin levels in preeclampsia and exercise counteract inflammatory and atherogenic activities while also having vascular protective effects. Exercise increases irisin levels that correlate negatively with fasting glucose, insulin concentration, and glycosylated hemoglobin levels. Irisin augments mRNA expression levels of UCP1 and cell death-inducing DNA fragmentation factor-like effector A (cidea) to cause browning of adipose tissue, increased thermogenesis, and increased energy consumption. Irisin concentrations in mothers with preeclampsia in the third trimester negatively correlate with systolic and diastolic blood pressure. Expression levels of chemerin, IL-6, and TNF-α are increased in gestational diabetes, and the increases in chemerin in late pregnancy positively correlate with the ratio of sFlt-1 to PlGF as a marker of preeclampsia. The effects of physical exercise on placentokines and exerkines in women at various stages of pregnancy remain poorly understood.

Circulating chemerin levels in preeclampsia: a systematic review and meta-analysis

BACKGROUND

Preeclampsia (PE) is a new-onset pregnancy-specific disorder with a high prevalence that leads to over 70 000 maternal and 500 000 foetal fatalities worldwide each year. The level of chemerin, a newly identified adipokine, is increased in diabetic and obese patients. Currently, there are several studies describing the relationship between maternal circulating chemerin levels and PE. Therefore, this study aimed to assess their association in pooled samples.

METHODS

Four databases were systematically searched to identify potential studies that reported circulating chemerin levels in PE and normal pregnancy groups. Standardized mean differences (SMDs), 95% confidence intervals (CIs), and 95% prediction intervals (PIs) were calculated using a random-effects meta-analysis. The probability of heterogeneity was also investigated by sensitivity analysis, subgroup analysis, and meta-regression.

RESULTS

Thirteen studies in 11 articles with a total of 860 PE patients and 1309 women with normal pregnancies met the inclusion criteria. The results of the meta-analysis revealed that circulating chemerin, which levels in PE patients were considerably higher than those in controls (SMD = 1.39, 95% CI: 1.02, 1.77, 95% PI: -0.07, 2.86). Moreover, sensitivity analysis determined that the outcomes of the overall pooled results were not affected after the elimination of any study. Notably, subgroup analysis demonstrated a similar expression pattern irrespective of geographic location, severity, timing of sampling, and sample size. Last, there were no factors that significantly impacted the overall estimate, according to meta-regression.

CONCLUSIONS

This meta-analysis is the first to assess circulating chemerin levels in PE patients. The findings indicate that circulating chemerin levels may be a potential marker to diagnose PE.

RISING STARS: Approaches to modeling placental function in preeclampsia in vitro and in vivo

Modeling preeclampsia remains difficult due to the nature of the disease and the unique characteristics of the human placenta. Members of the Hominidae superfamily have a villous hemochorial placenta that is different in structure from those of other therian mammals, including the mouse hemochorial placenta, making this common animal model less ideal for studying this disease. Human placental tissues delivered from pregnancies complicated by preeclampsia are excellent for assessing the damage the disease causes but cannot answer how or when the disease begins. Symptoms of preeclampsia manifest halfway through pregnancy or later, making it currently impossible to identify preeclampsia in human tissues obtained from an early stage of pregnancy. Many animal and cell culture models recapitulate various aspects of preeclampsia, though none can on its own completely capture the complexity of human preeclampsia. It is particularly difficult to uncover the cause of the disease using models in which the disease is induced in the lab. However, the many ways by which preeclampsia-like features can be induced in a variety of laboratory animals are consistent with the idea that preeclampsia is a two-stage disease, in which a variety of initial insults may lead to placental ischemia, and ultimately systemic symptoms. The recent development of stem cell-based models, organoids, and various coculture systems have brought in vitro systems with human cells ever closer to recapitulating in vivo events that lead to placental ischemia.

The Role of Chemerin in Metabolic and Cardiovascular Disease: A Literature Review of Its Physiology and Pathology from a Nutritional Perspective

Chemerin is a novel adipokine that plays a major role in adipogenesis and lipid metabolism. It also induces inflammation and affects insulin signaling, steroidogenesis and thermogenesis. Consequently, it likely contributes to a variety of metabolic and cardiovascular diseases, including atherosclerosis, diabetes, hypertension and pre-eclampsia. This review describes its origin and receptors, as well as its role in various diseases, and subsequently summarizes how nutrition affects its levels. It concludes that vitamin A, fat, glucose and alcohol generally upregulate chemerin, while omega-3, salt and vitamin D suppress it. Dietary measures rather than drugs acting as chemerin receptor antagonists might become a novel tool to suppress chemerin effects, thereby potentially improving the aforementioned diseases. However, more detailed studies are required to fully understand chemerin regulation.

Programming of metabolism by adipokines during development

The intrauterine and early postnatal periods represent key developmental stages in which an organism is highly susceptible to being permanently influenced by maternal factors and nutritional status. Strong evidence indicates that either undernutrition or overnutrition during development can predispose individuals to disease later in life, especially type 2 diabetes mellitus and obesity, a concept known as metabolic programming. Adipose tissue produces important signalling molecules that control energy and glucose homeostasis, including leptin and adiponectin. In addition to their well-characterized metabolic effects in adults, adipokines have been associated with metabolic programming by affecting different aspects of development. Therefore, alterations in the secretion or signalling of adipokines, caused by nutritional insults in early life, might lead to metabolic diseases in adulthood. This Review summarizes and discusses the potential role of several adipokines in inducing metabolic programming through their effects during development. The identification of the endocrine factors that act in early life to permanently influence metabolism represents a key step in understanding the mechanisms behind metabolic programming. Thus, future strategies aiming to prevent and treat these metabolic diseases can be designed, taking into consideration the relationship between adipokines and the developmental origins of health and disease.

Understanding the Role of Chemerin in the Pathophysiology of Pre-Eclampsia

Chemerin is a multifaceted adipokine that is involved in multiple biological processes, including inflammation, angiogenesis, adipogenesis, and energy metabolism, as well as oxidative stress. There is a vast body of evidence for a crucial role of chemerin in the development of different cardiovascular diseases. Blood chemerin levels, as well as its placental expression, are elevated in patients with pre-eclampsia (PE) and correlate positively with the severity of the disease. This narrative review summarizes the current knowledge about the potential role of chemerin during PE development, with a particular focus on its involvement in oxidative stress and endothelial dysfunction.

Third-Trimester Maternal Serum Chemerin and Hypertension After Preeclampsia: A Prospective Cohort Study

Background Limited data are available for postpartum hypertension prediction after preeclampsia. Methods and Results We examined the association between maternal serum chemerin levels in patients with preeclampsia and blood pressure (BP) levels after delivery in a prospective birth cohort of 15 041 singleton pregnant women. A total of 310 cases among 322 patients with preeclampsia (follow-up rate, 96.3%) were followed up during a mean 2.8 years after delivery. Compared with matched uncomplicated controls (n=310), serum chemerin measured at ≈35 gestational weeks was significantly increased in preeclampsia (171.8±49.2 versus 140.2±53.5 ng/mL; P<0.01) and positively correlated with the occurrence of postpartum hypertension, defined as either BP ≥130/80 mm Hg (per 1-SD increase: odds ratio [OR], 4.01 [95% CI, 2.77-5.81]) or as BP ≥140/90 mm Hg (per 1-SD increase: OR, 1.70 [95% CI, 1.28-2.25]) in patients with preeclampsia. The addition of chemerin levels improved the predictive performance of the clinical variable-derived prediction models for postpartum hypertension (for BP ≥130/80 mm Hg: area under the curve, 0.903 [95% CI, 0.869-0.937], Δ area under the curve, 0.070, P<0.001; for BP ≥140/90 mm Hg: area under the curve, 0.852 [95% CI, 0.803-0.902], Δ area under the curve, 0.030, P=0.002). The decision curve analysis revealed a net benefit of the chemerin-based prediction model for postpartum BP ≥130/80 mm Hg. Conclusions This study provides the first evidence supporting the independent predictive role of third-trimester maternal chemerin levels for postpartum hypertension after preeclampsia. Future study is warranted for external validation of this finding.

The impact of adipokines on vascular networks in adipose tissue

Adipose tissue (AT) is a highly active and plastic endocrine organ. It secretes numerous soluble molecules known as adipokines, which act locally to AT control the remodel and homeostasis or exert pleiotropic functions in different peripheral organs. Aberrant production or loss of certain adipokines contributes to AT dysfunction associated with metabolic disorders, including obesity. The AT plasticity is strictly related to tissue vascularization. Angiogenesis supports the AT expansion, while regression of blood vessels is associated with AT hypoxia, which in turn mediates tissue inflammation, fibrosis and metabolic dysfunction. Several adipokines can regulate endothelial cell functions and are endowed with either pro- or anti-angiogenic properties. Here we address the role of adipokines in the regulation of angiogenesis. A better understanding of the link between adipokines and angiogenesis will open the way for novel therapeutic approaches to treat obesity and metabolic diseases.

Adipokine chemerin overexpression in trophoblasts leads to dyslipidemia in pregnant mice: implications for preeclampsia

BACKGROUND

The adipokine chemerin regulates adipogenesis and the metabolic function of both adipocytes and liver. Chemerin is elevated in preeclamptic women, and overexpression of chemerin in placental trophoblasts induces preeclampsia-like symptoms in mice. Preeclampsia is known to be accompanied by dyslipidemia, albeit via unknown mechanisms. Here, we hypothesized that chemerin might be a contributor to dyslipidemia.

METHODS

Serum lipid fractions as well as lipid-related genes and proteins were determined in pregnant mice with chemerin overexpression in placental trophoblasts and chemerin-overexpressing human trophoblasts. In addition, a phospholipidomics analysis was performed in chemerin-overexpressing trophoblasts.

RESULTS

Overexpression of chemerin in trophoblasts increased the circulating and placental levels of cholesterol rather than triglycerides. It also increased the serum levels of lysophosphatidic acid, high-density lipoprotein cholesterol (HDL-C), and and low-density lipoprotein cholesterol (LDL-C), and induced placental lipid accumulation. Mechanistically, chemerin upregulated the levels of peroxisome proliferator-activated receptor g, fatty acid-binding protein 4, adiponectin, sterol regulatory element-binding protein 1 and 2, and the ratio of phosphorylated extracellular signal-regulated protein kinase (ERK)1/2 / total ERK1/2 in the placenta of mice and human trophoblasts. Furthermore, chemerin overexpression in human trophoblasts increased the production of lysophospholipids and phospholipids, particularly lysophosphatidylethanolamine.

CONCLUSIONS

Overexpression of placental chemerin production disrupts trophoblast lipid metabolism, thereby potentially contributing to dyslipidemia in preeclampsia.

Chemerin-Induced Down-Regulation of Placenta-Derived Exosomal miR-140-3p and miR-574-3p Promotes Umbilical Vein Endothelial Cells Proliferation, Migration, and Tube Formation in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) leads to poor pregnancy outcomes and fetoplacental endothelial dysfunction; however, the underlying mechanisms remain unknown. This study aimed to investigate the effect of placenta-derived exosomal miRNAs on fetoplacental endothelial dysfunction in GDM, as well as to further explore the role of chemerin to this end. Placenta-derived exosomal miR-140-3p and miR-574-3p expression (next-generation sequencing, quantitative real-time PCR), its interactions with cell function (Cell Counting Kit-8, Transwell, tube formation assay), chemerin interactions (Western blotting), and placental inflammation (immunofluorescence staining, enzyme-linked immunosorbent assay) were investigated. Placenta-derived exosomal miR-140-3p and miR-574-3p were downregulated in GDM. Additionally, miR-140-3p and miR-574-3p inhibited the proliferation, migration, and tube formation ability of umbilical vein endothelial cells by targeting vascular endothelial growth factor. Interestingly, miR-140-3p and miR-574-3p expression levels were negatively correlated with chemerin, which induced placental inflammation through the recruitment of macrophage cells and release of IL-18 and IL-1β. These findings indicate that chemerin reduces placenta-derived exosomal miR-140-3p and miR-574-3p levels by inducing placental inflammation, thereby promoting the proliferation, migration, and tube formation of umbilical vein endothelial cells in GDM, providing a novel perspective on the underlying pathogenesis and therapeutic targets for GDM and its offspring complications.

Chemerin: A Functional Adipokine in Reproductive Health and Diseases

As a multifaceted adipokine, chemerin has been found to perform functions vital for immunity, adiposity, and metabolism through its three known receptors (chemokine-like receptor 1, CMKLR1; G-protein-coupled receptor 1, GPR1; C-C motif chemokine receptor-like 2, CCRL2). Chemerin and the cognate receptors are also expressed in the hypothalamus, pituitary gland, testis, ovary, and placenta. Accumulating studies suggest that chemerin participates in normal reproduction and underlies the pathological mechanisms of certain reproductive system diseases, including polycystic ovary syndrome (PCOS), preeclampsia, and breast cancer. Herein, we present a comprehensive review of the roles of the chemerin system in multiple reproductive processes and human reproductive diseases, with a brief discussion and perspectives on future clinical applications.

The Regulatory Roles of Chemerin-Chemokine-Like Receptor 1 Axis in Placental Development and Vascular Remodeling During Early Pregnancy

Chemerin is an adipokine that regulates metabolism in pregnancy. An elevation of serum chemerin level is associated with pregnancy complications. Consistently, we demonstrated that the chemerin expression was increased in placenta of preeclamptic patients at deliveries. The G protein-coupled receptor chemokine-like receptor 1 (CMKLR1) mediates the actions of chemerin. The functions of the chemerin-CMKLR1 axis in maintaining pregnancy are still unknown. In this study, we demonstrated that CMKLR1 was expressed in the decidual natural killer (dNK) cells and chorionic villi of human. Chemerin suppressed the proliferation of the dNK cells in vitro. Specific antagonist of CMKLR1, α-Neta abolished the suppressive effect of spent medium from chemerin-treated dNK cells culture on extravillous trophoblast invasion. Activation of the chemerin-CMKLR1 axis promoted fusion and differentiation of human cytotrophoblast to syncytiotrophoblast in vitro. We generated Cmklr1 knockout mice and showed that the Cmklr1 deficiency negatively affected pregnancy outcome in terms of number of implantation sites, litter size and fetal weight at birth. Histologically, the Cmklr1 deficiency impaired formation of the syncytiotrophoblast layer II, induced enlargement of the maternal lacunae in the labyrinth, increased the diameter of the spiral arteries and increased trophoblast invasion in the decidua. The Cmklr1 deficient placenta also displayed an increased number of dNK cells and serum IL-15 level. In summary, the chemerin-CMKLR1 axis regulated placental development and spiral artery remodeling in early pregnancy.

Chemerin Effect on the Endometrial Proteome of the Domestic Pig during Implantation Obtained by LC-MS/MS Analysis

Chemerin (CHEM) is a hormone mainly expressed in adipocytes involved in the regulation of energy homeostasis and inflammatory response. CHEM expression has been demonstrated in the structures of the porcine hypothalamic-pituitary-gonadal axis, as well as in the uterus, trophoblasts and conceptuses of pigs. In this study, we performed high-throughput proteomic analyses (liquid chromatography with tandem mass spectrometry, LC-MS/MS) to examine the influence of CHEM (400 ng/mL) on differentially regulated proteins (DRPs) in the porcine endometrial tissue explants during implantation (15 to 16 days of gestation). Among all 352 DRPs, 164 were up-regulated and 188 were down-regulated in CHEM-treated group. DRPs were assigned to 47 gene ontology (GO) terms (p-adjusted < 0.05). Validation of four DRPs (IFIT5, TGFβ1, ACO1 and PGRMC1) by Western blot analysis confirmed the veracity and accuracy of the LC-MS/MS method used in the present study. We suggest that CHEM, by modulating various protein expressions, takes part in the endometrial cell proliferation, migration and invasion at the time of implantation. It also regulates the endometrial immune response, sensitivity to P4 and the formation of new blood vessels. Additionally, CHEM appears to be an important factor involved in endothelial cell dysfunction during the pathogenesis of preeclampsia. The identification of a large number of DRPs under the influence of CHEM provides a valuable resource for understanding the molecular mechanisms of this hormone action during implantation, which is a prerequisite for better control of pig reproduction.