Adiponectin Concentrations in Maternal Serum: Elevated in Preeclampsis But Unrelated to Insulin Sensitivity

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.

Preeclampsia and Obesity-The Preventive Role of Exercise

Obesity is now recognized as a worldwide epidemic. An inadequate diet and reduced physical activity are acknowledged as the leading causes of excess body weight. Despite growing evidence that obesity is a risk factor for unsuccessful pregnancies, almost half of all women who become pregnant today are overweight or obese. Common complications of pregnancy in this group of women are preeclampsia and gestational hypertension. These conditions are also observed more frequently in women with excessive weight gain during pregnancy. Preeclampsia is one of the most serious pregnancy complications with an unpredictable course, which in its most severe forms, threatens the life and health of the mother and her baby. The early identification of the risk factors for preeclampsia development, including obesity, allows for the implementation of prophylaxis and a reduction in maternal and fetal complications risk. Additionally, preeclampsia and obesity are the recognized risk factors for developing cardiovascular disease in later life, so prophylaxis and treating obesity are paramount for their prevention. Thus, a proper diet and physical activity might play an essential role in the prophylaxis of preeclampsia in this group of women. Limiting weight gain during pregnancy and modifying the metabolic risk factors with regular physical exercise creates favorable metabolic conditions for pregnancy development and benefits the elements of the pathogenetic sequence for preeclampsia development. In addition, it is inexpensive, readily available and, in the absence of contraindications to its performance, safe for the mother and fetus. However, for this form of prevention to be effective, it should be applied early in pregnancy and, for overweight and obese women, proposed as an essential part of planning pregnancy. This paper aims to present the mechanisms of the development of hypertension in pregnancy in obese women and the importance of exercise in its prevention.

Angiogenic Imbalance and Inflammatory Biomarkers in the Prediction of Hypertension as Well as Obstetric and Perinatal Complications in Women with Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) increases the risk of hypertensive disorders of pregnancy (HDP). We aimed to analyze the altered inflammatory markers and angiogenic factors among women with GDM to identify pregnant women at higher risk of developing HDP. Methods: This was a prospective study of 149 women without hypertension diagnosed in the third trimester with GDM. Inflammatory markers and angiogenic factors were measured at 28−32 weeks of pregnancy. Obstetric and perinatal outcomes were evaluated. Results: More than eight percent of the women developed HDP. Higher levels of the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PIGF) ratio (4.9 ± 2.6 versus 2.3 ± 1.3, respectively; p < 0.001) and leptin (10.9 ± 0.8 versus 10.08 ± 1.1, respectively; p = 0.038), as well as lower levels of adiponectin (10.5 ± 1.3 versus 12.9 ± 2.7, respectively; p = 0.031), were seen in women who developed HDP versus normotensive women with GDM. A multivariable logistic regression analysis showed that adiponectin had a protective effect with 0.45-fold odds (0.23−0.83; p = 0.012), and that the sFlt-1/PIGF ratio was associated with 2.70-fold odds of developing HDP (CI 95%: 1.24−5.86; p = 0.012). Conclusion: An increase in angiogenic imbalance in the sFlt-1/PIGF ratio in women with GDM was detected and may be an indicator of developing HDP in addition to any subsequent obstetric and perinatal complications.

Evaluation of the Blood Level of Adiponectin in Pregnant Adolescents

OBJECTIVE

 To evaluate serum levels of adiponectin in pregnant adolescents between 30 and 36 weeks of gestation.

METHOD

 A prospective cross-sectional study enrolled 67 normal pregnant women between 30 and 36 weeks of gestation and eutrophic (body mass index [BMI]: 18.5-25 kg/m2), of which 36 were adolescents (< 20 years old) and 31 adults (≥ 20 years old). Serum adiponectin levels were determined by enzyme-linked immunosorbent assay (ELISA). The t-student or Mann-Whitney tests were used for intergroup comparison.

RESULTS

 Pregnant adolescents showed significantly higher serum adiponectin concentrations compared with pregnant adults (p = 0.04). No differences were observed in adiponectin levels in younger pregnant adolescents (< 16 years old) compared with older pregnant adolescents (≥ 16 years old). Adiponectin values were divided into 3 subgroups: < 3,000 ng/mL, between 3,000 and 5,000 ng/mL, and > 5,000 ng/mL. Birthweight was significantly higher in women > 5,000 ng/mL when compared with < 3,000 ng/mL in the adolescent group. No association between pregestational adiponectin levels and BMI, gestational weight gain, and gestational age was observed; however, there was a positive relation with birthweight (p = 0.0239).

CONCLUSION

 Serum adiponectin values in pregnant adolescents between 30 and 36 weeks of gestation were higher compared with pregnant adults; however, no differences between younger and older pregnant adolescents were observed.

Serum adipocytokines and adiposity as predictive indices of preeclampsia

BACKGROUND

This study was aimed at determining the levels of serum adiponectin, leptin, resistin, visfatin and lipids during the first trimester in pregnant women and to evaluate the relationship between these biochemical markers and preeclampsia (PE). Available evidence point to changes in the levels of these adipokines in PE hence this study examined the potential of using these biomarkers in the prediction of the disease.

METHODS

This was a case-control study which compared first trimester serum biochemical and anthropometric parameters in pregnant women who subsequently developed PE and those who did not. Blood pressure and urine protein were determined after 20 weeks of gestation and diagnosis of PE performed according to the guidelines of the American Heart Association.

RESULTS

There was no significant difference (p > 0.05) in the lipid profile with the exception of HDL cholesterol which was significantly lower (p = 0.043) in the PE group compared to the normotensive group. There were, however, significant differences (p <  0.05) in the adipokines between the PE group and those without PE. Analyses of area under the receiver operating characteristic curves (AUCs) for the adipokines, showed their ability to correctly predict PE even after controlling for body mass index (BMI) and family history of hypertension.

CONCLUSION

Adiponectin, leptin, resistin and visfatin were found to be significant predictors of PE, with resistin being the best predictor after controlling for BMI. However, adiponectin was the best predictor after controlling for BMI, age, parity and family history of diabetes and preeclmapsia.

The role of serum adipokine levels in preeclampsia: A systematic review

BACKGROUND

Preeclampsia represents a major pregnancy complication, associated with high rates of perinatal morbidity. The aim of this systematic review is to accumulate current literature evidence in order to examine the pattern of serum adipokine levels among preeclamptic women and asses their potential efficacy in the prediction of the disease.

METHODS

Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched from inception. All observational studies reporting serum adipokine values among preeclamptic and healthy pregnant women were held eligible.

RESULTS

A total of 163 studies were included, comprising 23,482 women. Leptin was evaluated in 91 studies and its values were found to be significantly elevated in preeclamptic women during all pregnancy trimester, independently of disease onset and severity. Preeclampsia was also associated with increased serum fatty acid binding protein-4 and chemerin levels, when measured both during the 1st and 3rd trimester. Data concerning the rest adipokines were either conflicting or limited to reach firm conclusions. Quality of evidence was evaluated to be high for leptin, moderate for serum fatty acid binding protein-4 and chemerin and low for the other adipokines.

CONCLUSIONS

The existing evidence suggests that preeclampsia is linked to increased levels of leptin, chemerin and fatty acid binding protein-4 in all pregnancy trimesters and forms of the disease. Inconsistent data currently exists concerning the role of the other adipokines. Large-scale prospective studies should longitudinally evaluate the serum concentration of novel adipokines and define the optimal threshold and timing of measurement to be widely applied in clinical practice.

Adipokines and Endothelium Dysfunction Markers in Pregnant Women with Gestational Hypertension

Objective

The aim of the study was to evaluate the levels of adipokines such as adiponectin and leptin as well as soluble intercellular adhesion molecule-1 (sICAM-1) and endogenous NOS inhibitor-asymmetric dimethylarginine (ADMA), as the endothelium dysfunction markers in pregnant women with gestational hypertension (GH).

Patients and Methods

Adiponectin, leptin, sICAM-1, and ADMA concentrations were measured in a group of 34 patients with GH and in 32 healthy pregnant women between the 24^th and 34^th week of gestation with ELISA tests.

Results

The patients with GH compared with healthy ones were characterized by significantly higher BMI (28.09 ± 7.90 vs. 22.34 ± 4.21 kg/m², p=0.016) and higher concentrations of leptin (45.89 ± 35.91 vs. 24.09 ± 24.40 ng/mL, p=0.006). sICAM-1 levels were also higher in the GH group but without the statistical significance (264.51 ± 50.99 vs. 232.56 ± 43.3 ng/ml, p=0.057). There were no significant differences between groups in adiponectin (8.79 ± 8.67 vs. 7.90 ± 3.71 μg/mL, p=0.46, NS) and ADMA (0.57 ± 0.26 vs. 0.60 ± 0.24 μmol/L, p=0.68, NS) levels. The significant correlation between leptin levels and BMI value was observed only in patients with GH (R = 0.56, p=0.02).

Conclusions

The higher levels of leptin in pregnant women with gestational hypertension may be suggestive of the role of leptin in GH development. As the patients in the GH group had higher BMI, hyperleptinemia may link obesity with gestational hypertension. The significance of leptin as the predictive marker of GH development could be implied. It could be postulated that the higher levels of sICAM-1 in the GH patients, although not statistically significant, could reflect some impairment of the endothelium function occurring in GH regardless of BMI. The comparable adiponectin levels in GH and healthy pregnant patients and the lack of its correlation with BMI may indicate the occurrence of a protective mechanism in pregnancy maintaining its concentration and preserving from the consequences of the decrease in its levels in overweight and obese patients. Since ADMA levels were similar in GH and healthy pregnant women, ADMA seems not to be involved in GH pathogenesis, suggesting that NO synthesis is not impaired in this pregnancy complication. As the data on the gestational hypertension pathogenesis and its correlations with adipokines and markers of the endothelium dysfunction are limited, further studies on this issue are warranted.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

The roles of leptin and adiponectin at the fetal-maternal interface in humans

Infertility now affects one in seven couples, and the prevalence of this condition continues to increase. Ovulatory defects and unknown causes account for more than half of the cases of infertility. It has been postulated that a significant proportion of these cases are directly or indirectly related to obesity, since the presence of excess adipose tissue has a variety of effects on reproductive function. Here, we review on the effects of the two major adipokines (leptin and adiponectin) on fertility, with a focus on the first steps in embryo implantation and the key components of fetal-maternal interface (the placenta and the endometrium). These adipokines are reportedly involved in the regulation of cell proliferation and differentiation, and as such affect local angiogenesis, immune tolerance and inflammatory processes in placental and endometrial tissues. In placental cells, leptin and adiponectin also modulate trophoblast invasiveness and the nutrient supply. These observations strongly suggest by interfering with the placenta and endometrium, adipokines can create a favorable environment for embryo implantation and have a key role in fetal-maternal metabolism, fetal-maternal communication, and gestation. Given that reproductive functions are tightly coupled to the energy balance, metabolic abnormalities may lead to the development of complications of pregnancy and changes in fetal growth. In this context, we suggest that the leptin/adiponectin ratio may be a clinically valuable marker for detecting a number of pathologies in pregnancy.

CpG Oligodeoxynucleotides Downregulate Placental Adiponectin and Increase Embryo Loss in Non-Obese Diabetic Mice

PROBLEM

CpG oligodeoxynucleotides (ODNs) can induce immunological changes in non-obese diabetic (NOD) mice and increase embryo loss, but little is known about the mechanism. This study aimed to determine the role of adiponectin in CpG ODN-induced pregnancy failure.

METHOD OF STUDY

Oligodeoxynucleotide 1826 was intraperitoneally injected to NOD mice, and ODN 2216, ODN 2006, and ODN 2395 were used to stimulate human trophoblast cell lines to investigate adiponectin expression patterns and its possible effects on trophoblast function.

RESULTS

CpG ODNs downregulated adiponectin via the cJun N-terminal kinase signaling pathway and led to increased embryo loss (from 6.9 to 33.3%). ODN 2006 impaired human trophoblast cell migration, which was successfully rescued by adiponectin treatment.

CONCLUSION

CpG ODNs decreased placental adiponectin expression in NOD mice and impaired human trophoblast function and was associated with increased embryo loss. Adiponectin may therefore play an important protective role in the prevention of bacteria-induced pregnancy failure.

Characterization of Visceral and Subcutaneous Adipose Tissue Transcriptome and Biological Pathways in Pregnant and Non-Pregnant Women: Evidence for Pregnancy-Related Regional-Specific Differences in Adipose Tissue

Objective

The purpose of this study was to compare the transcriptome of visceral and subcutaneous adipose tissues between pregnant and non-pregnant women.

Study Design

The transcriptome of paired visceral and abdominal subcutaneous adipose tissues from pregnant women at term and matched non-pregnant women (n = 11) was profiled with the Affymetrix Human Exon 1.0 ST array. Differential expression of selected genes was validated with the use of quantitative reverse transcription–polymerase chain reaction.

Results

Six hundred forty-four transcripts from 633 known genes were differentially expressed (false discovery rate (FDR) <0.1; fold-change >1.5), while 42 exons from 36 genes showed differential usage (difference in FIRMA scores >2 and FDR<0.1) between the visceral and subcutaneous fat of pregnant women. Fifty-six known genes were differentially expressed between pregnant and non-pregnant subcutaneous fat and three genes in the visceral fat. Enriched biological processes in the subcutaneous adipose tissue of pregnant women were mostly related to inflammation.

Conclusion

The transcriptome of visceral and subcutaneous fat depots reveals pregnancy-related gene expression and splicing differences in both visceral and subcutaneous adipose tissue. Furthermore, for the first time, alternative splicing in adipose tissue has been associated with regional differences and human parturition.

The Role of Obesity in Preeclampsia

The incidence of obesity is increasing at an alarming rate. There is compelling evidence that obesity increases the risk of preeclampsia about 3-fold, and in developed countries is the leading attributable risk for the disorder. In this presentation we explore this relationship and propose targets for future studies guided by the much more extensively studied relationship of obesity to cardiovascular disease. We further address the hypothesis that asymmetric dimethyl arginine (ADMA), an endogenous inhibitor of nitric oxide synthase, may be one convergence point for the mechanism by which obesity increases the risk of preeclampsia. We conclude with consideration of the clinical implications of this information.

Critical periods of increased fetal vulnerability to a maternal high fat diet

BACKGROUND

Fetal adaptations to high fat (HF) diet in utero (IU) that may predispose to Metabolic Syndrome (MetS) in adulthood include changes in fetal hepatic gene expression. Studies were performed to determine whether maternal exposure to HF diet at different stages during pregnancy had different effects on the fetus, including hepatic gene expression.

METHODS

Female wild type mice were fed either a HF or breeding chow (C) for 2 wks prior to mating. The experimental groups were composed of embryonic day (e) 18.5 fetuses obtained from WT female mice that were fed HF (HF, 35.5% fat) or breeding chow (C, 9.5% fat) for 2 wk before mating until e9.5 of pregnancy (periconception-midpregnancy). At e9.5 dams were switched to the opposite diet (C-HF or HF-C).

RESULTS

Exposure to HF diet throughout pregnancy reduced maternal weight gain compared to C diet (p < 0.02 HF vs. C). HF-C dams had significantly decreased adiponectin levels and litter size when compared to C-HF (p < 0.02 HF-C vs C-HF). Independent of the timing of exposure to HF, fetal weight and length were significantly decreased when compared to C diet (HF, C-HF and HF-C vs. C p < 0.02). HF diet during the second half of pregnancy increased expression of genes in the fetal liver associated with fetal growth (C-HF vs C p < 0.001), glucose production (C-HF vs C p < 0.04), oxidative stress and inflammation (C-HF vs C p < 0.01) compared to C diet.

CONCLUSIONS

This model defines that there are critical periods during gestation in which the fetus is actively shaped by the environment. Early exposure to a HF diet determines litter size while exposure to HF during the second half of pregnancy leads to dysregulation of expression of key genes responsible for fetal growth, hepatic glucose production and oxidative stress. These findings underscore the importance of future studies designed to clarify how these critical periods may influence future risk of developing MetS later in life.

Adiponectin serum concentrations in newborn at delivery appear to be of fetal origin

OBJECTIVE

Adiponectin (APN) may play a role in adapting energy metabolism at the maternal-fetal unit. The aim of the study was to investigate the relationship between placental APN mRNA expression, maternal serum APN concentration and umbilical cord serum APN concentration in full-term healthy newborns.

METHODS

Serum APN levels were compared in 46 samples (23 from healthy newborns; gestational age 37.0 to 41.5 weeks) and their mothers (n=23). The APN concentration was measured using enzyme linked immunosorbent assay (ELISA). We analyzed the mRNA expression profile of APN in 22 placenta tissue samples using real time polymerase chain reaction (RT-PCR).

RESULTS

The highest APN serum concentrations were found in umbilical cord blood, these were significantly higher than maternal APN levels (mean concentration±SD; 38.48±12.8 vs. 6.6±2.3 μg/mL, p<0.001). Otherwise, there were no significant correlation between maternal APN and umbilical cord APN concentration. APN gene expression was very low and only found in 8 out of 22 placentas. There were no significant correlation between placental APN mRNA and umbilical cord serum APN or maternal serum APN concentration. Umbilical cord APN concentrations were positively associated with birth weight (r=0.535; p=0.012) and gestational age (r=0.559; p=0.013). Maternal APN concentration revealed a negative correlation between maternal body weight (r=-0.623; p=0.009) and body mass index (BMI) (r=-0.634; p=0.008) at delivery. Additionally, no significant correlation was found between newborn birth weight and maternal weight.

CONCLUSIONS

This study suggests that high serum APN concentrations in umbilical cord blood are not regulated by placental APN mRNA gene expression. The high concentration of APN in cord blood is independent from maternal APN concentration, suggesting an important physiological role of APN and implicating that umbilical APN concentration reflects its exclusive production by fetal tissues.

Different profile of serum leptin between early onset and late onset preeclampsia

Aim. This study was designed to clarify the role of leptin and adiponectin in preeclampsia (PE) pathogenesis and different subtypes of preeclampsia. Method. This case control study was performed in 45 PE patients and 45 healthy controls matched for age, BMI, and ethnicity. Serum leptin and adiponectin levels were determined by enzyme linked immunosorbent assay (ELISA). Results. Maternal serum leptin and adiponectin were significantly higher in PE women than controls. Serum leptin was elevated in early onset preeclampsia (EOPE) and late onset preeclampsia (LOPE) compared to controls. Among PE patients, serum leptin was higher in EOPE than LOPE women. However, serum adiponectin was not different between EOPE and LOPE women. The serum leptin was significantly higher in severe PE than mild PE. The serum adiponectin was significantly elevated in severe PE compared to controls. Significant positive correlation was observed between leptin and adiponectin and also between leptin and BMI in controls. Moreover significant positive correlation was observed between adiponectin and BMI in PE patients and controls. Conclusion. The present study showed that serum leptin level may play a significant role as a biomarker to differentiate early and late onset PE and also its relation to BMI and severity of disease.

Chemerin is present in human cord blood and is positively correlated with birthweight

OBJECTIVE

Chemerin, a novel adipokine, has been implicated in adipogenesis, inflammation, and metabolism. The aims of this study were to determine the presence of chemerin in cord blood and its association with birthweight.

STUDY DESIGN

This cross-sectional study included the following: (1) twins with (n = 24) or without (n = 28) birthweight discordancy; and (2) singletons subclassified into small-for-gestational-age (SGA; n = 18); appropriate for gestational age (AGA; n = 33); and large-for-gestational-age (LGA; n = 8). Cord blood chemerin was determined. Parametric and nonparametric statistics were used for analysis.

RESULTS

The results of the study included the following: (1) within the discordant twins group, the median chemerin concentration was significantly lower in the SGA group than in their cotwins; (2) within singletons, the median chemerin concentration was significantly higher in the LGA than the AGA newborns; and (3) the regression model revealed that chemerin was independently associated with birthweight.

CONCLUSION

Cord blood chemerin is present in cord blood and its concentrations are positively correlated with birthweight. These novel findings support a role of adipokines in fetal growth.

Adipokines, an adipose tissue and placental product with biological functions during pregnancy

Latter half of pregnancy is characterized by a "physiological diabetogenic state" since changes in insulin-sensitivity have been well documented. These changes ensure continuous supply of nutrients to the growing fetus. In the last years the role of adipocyte-derived signaling molecules, collectively known as adipokines has been object of different in vitro and in vivo studies. Of interest, adipokines and/or their receptors are expressed in the placental tissue which, therefore, can contribute to development of maternal insulin-resistance and, as a consequence, fetal growth. Leptin, adiponectin, and resistin represent the most well studied adipokines and, with the exception of adiponectin, their serum and placental levels increase as pregnancy progresses. High levels of adipokines have also been detected in umbilical plasma hence suggesting a possible role on fetal development and metabolism; however, it remains still unclear if such adipokines can directly stimulate fetal tissues development acting as growth factors. In addition to their well known metabolic effects, we also reported studies describing the role of adipokines in promoting proliferation and invasiveness of trophoblast cells and affecting local angiogenic processes. These observations strongly suggest that adipokines, by alternatively interfering with placental development, may affect pregnancy outcome and fetal growth. However, further studies are needed to better understand the local regulation of their expression. © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Adiponectin and reproduction

Adiponectin is an adipocyte-derived cytokine that acts as a major regulator of insulin sensitivity. Adiponectin deficiency can result in severe diabetes and metabolic disorders in humans. Since its discovery, our understanding of adiponectin's biological functions has expanded from insulin sensitization properties to new effects on inflammation, immunology, and human reproduction. Indeed, both obesity and excessive leanness are associated with reproductive dysfunction. The objective of this chapter is to review such biological actions and the potential roles of adiponectin on human reproduction. There is accumulative evidence for direct effects of this adipokine on the late stages of folliculogenesis and on the development of a functional placenta. In addition, clinical and genomic studies associate hypoadiponectinemia with pregnancy-related disorders, including polycystic ovarian syndrome.

Leptin, adiponectin and other adipokines in gestational diabetes mellitus and pre-eclampsia

Proteins secreted from adipocytes - so-called adipokines - influence metabolic and vascular function. Recent data suggest that various adipokines are dysregulated in gestational diabetes mellitus (GDM) and pre-eclampsia (PE) and might be of pathophysiological and prognostic significance in these complications of pregnancy. This review gives an overview on the regulation and pathophysiology of leptin and adiponectin in GDM and PE. Furthermore, data on novel adipokines including resistin, visfatin, retinol-binding protein 4 and vaspin are summarized.

Insulin sensitivity in late gestation and early postpartum period: the role of circulating maternal adipokines

OBJECTIVE

Early postpartum period is characterised by a dramatic decrease in insulin resistance and significant metabolic alterations. The aims of this study were to determine the changes in circulating maternal concentrations of total adiponectin, adiponectin multimers, leptin and resistin before and after the delivery and to explore their relationship with insulin sensitivity.

METHODS

Twenty-seven normal pregnant women at term were included in this longitudinal study. Blood samples were taken before and 4 days after elective caesarean section. Total adiponectin, adiponectin multimers, leptin, resistin, glucose, insulin and prolactin were measured in maternal serum. Adiponectin multimers were measured before and after the delivery in eight women.

RESULTS

(1) The mean maternal serum total adiponectin concentration was significantly higher before than after delivery while the relative distribution of circulating maternal adiponectin multimers did not change after delivery; (2) the median maternal serum concentration of leptin was significantly higher in the antepartum than in the postpartum period; (3) the median maternal serum resistin concentration was comparable before and after delivery; (4) multiple linear regression analysis revealed that antepartum insulin sensitivity was associated with maternal low body mass index, and low glucose concentrations in glucose challenge test, as well as with maternal age and increased leptin concentrations. Postpartum insulin sensitivity was associated with decreased circulating resistin concentrations.

CONCLUSIONS

Despite increase in insulin sensitivity, early postpartum period is characterised by a decrease in maternal circulating total adiponectin and by steady concentrations of resistin and adiponectin multimers compared to the late third trimester.

Could alterations in maternal plasma visfatin concentration participate in the phenotype definition of preeclampsia and SGA?

OBJECTIVE

Women with preeclampsia and those who delivered a small-for-gestational-age (SGA) neonate share several mechanisms of disease, including chronic uteroplacental ischemia and failure of physiologic transformation of the spiral arteries. However, the clinical manifestation of these obstetrical syndromes is remarkably different. It has been proposed that an altered maternal metabolic state, as well as a unique circulating cytokines milieu, predispose women to develop either preeclampsia or SGA. Compelling evidence suggests that adipose tissue orchestrates both metabolic pathways and immunological responses via the production of adipokines. Visfatin is a novel adipocytokine with metabolic and immunomodulating properties. The objective of this study was to determine whether preeclampsia and SGA are associated with alterations in maternal circulating visfatin concentrations.

METHODS

This cross-sectional study included pregnant women in the following groups: (1) normal pregnancy (n = 158); (2) patients with preeclampsia (n = 43) of which 32 had an AGA and 11 had an SGA neonate; (3) patients without preeclampsia who delivered an SGA neonate (n = 55). Maternal plasma visfatin concentrations were measured by ELISA. Nonparametric tests and multiple linear regression analysis were used.

RESULTS

(1) Women who delivered an SGA neonate had a higher median maternal plasma visfatin concentration than those with a normal pregnancy (20.0 ng/ml, interquartile range: 17.2-24.6 vs. 15.2 ng/ml, 12.1-19.2, respectively; P < 0.001) and than those with preeclampsia (14.5 ng/ml, 12.5-18.7; P < 0.001); (2) the median maternal plasma visfatin concentration did not differ significantly between patients with preeclampsia and those with a normal pregnancy (P = 0.8); (3) among patients with preeclampsia, there was no significant difference in the median maternal plasma visfatin concentration between those with or without an SGA neonate (P = 0.5); (4) in a linear regression model, delivery of an SGA neonate and pregestational body mass index were independently associated with increased visfatin concentration after adjustment for confounding factors (maternal age, smoking, gestational age at blood collection and the presence of preeclampsia or SGA).

CONCLUSION

(1) Patients with SGA, but not those with preeclampsia, had a higher maternal plasma visfatin concentration than those with a normal pregnancy; (2) this finding suggests differential involvement of visfatin in SGA and preeclampsia; (3) we propose that changes in circulating maternal visfatin concentration may be implicated in the phenotypic definitions and distinction of preeclampsia and SGA.

Evidence for differential regulation of the adipokine visfatin in the maternal and fetal compartments in normal spontaneous labor at term

OBJECTIVE

Visfatin, a novel adipokine with metabolic and immunoregulatory properties, has been implicated in the regulation of fetal growth, as well as in preterm labor. A gap in knowledge is whether spontaneous labor at term is associated with changes in the maternal and fetal concentrations of visfatin. The aim of this study was to determine if the presence of labor at term is associated with alterations in maternal and neonatal plasma visfatin concentrations.

STUDY DESIGN

This cross-sectional study included 50 normal pregnant women at term and their appropriate-for-gestational age (AGA) neonates in the following groups: 1) 25 mother-neonate pairs delivered by elective cesarean section without spontaneous labor, and 2) 25 mother-neonate pairs who delivered vaginally following spontaneous labor. Maternal plasma and cord blood visfatin concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) The median visfatin concentration was higher in umbilical cord plasma of neonates born following a spontaneous labor at term than that of those who were born by an elective cesarean section (P=0.02); 2) in contrast, the median maternal plasma visfatin concentration did not differ significantly between patients with and without labor (P=0.44); and 3) there was a significant correlation between umbilical cord plasma concentration of visfatin and both maternal visfatin concentration (r=0.54, P=0.005) and gestational age (GA) at delivery (r=0.58; P=0.002) only in the absence of labor.

CONCLUSION

Term labor is associated with increased fetal, but not maternal, circulating visfatin concentrations. Previous reports indicate that preterm labor leading to preterm delivery is characterized by an increase in maternal plasma concentrations of visfatin. The observations reported herein support the view that there are fundamental differences in the endocrine and metabolic adaptations in normal labor at term and preterm labor.

Adiponectin in amniotic fluid in normal pregnancy, spontaneous labor at term, and preterm labor: a novel association with intra-amniotic infection/inflammation

OBJECTIVE

Adiponectin, an anti-inflammatory and anti-diabetogenic adipokine, has an important regulatory effect on both the innate and adaptive limbs of the immune response. The objective of this study was to determine whether adiponectin is present in amniotic fluid (AF) and if its concentration changes with gestational age, in the presence of labor, and in the presence of intra-amniotic infection (IAI) in patients with spontaneous preterm labor (PTL) and intact membranes.

STUDY DESIGN

This cross-sectional study included 468 patients in the following groups: (1) women in the mid-trimester of pregnancy (14-18 weeks) who underwent amniocentesis for genetic indications and delivered a normal neonate at term (n = 52); (2) normal pregnant women at term with (n = 49) and without (n = 41) spontaneous labor; (3) patients with an episode of PTL and intact membranes who were classified into: (a) PTL who delivered at term (n = 149); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 108); and (c) PTL with IAI (n = 69). Adiponectin concentration in AF was determined by ELISA.

RESULTS

(1) The median AF adiponectin concentration at term was significantly higher than in the mid-trimester (35.6 ng/ml, interquartile range [IQR] 26.4-52.7 vs. 29.9 ng/ml, IQR 19.9-35.2; p = 0.01); (2) among women with PTL and intact membranes, the median AF adiponectin concentration was significantly higher in patients with IAI than in those without IAI who delivered either at term (54.3 ng/ml, 39.0-91.8 vs. 50.1 ng/ml, 33.2-72.8; p = 0.02) or preterm (47.6 ng/ml, 32.6-74.6; p = 0.01); and (3) among women at term, there was no significant difference in the median AF adiponectin concentration between those with and without labor (33.7 ng/ml, IQR 21.7-53.9 vs. 35.6 ng/ml, IQR 26.4-52.7; respectively p = 0.5).

CONCLUSIONS

(1) Adiponectin is a physiologic constituent of AF; and (2) adiponectin concentrations in AF are increased significantly with advancing gestation and in the presence of IAI. Collectively, these findings suggest that adiponectin plays a dynamic role in normal gestation and in the presence of IAI.

Adiponectin induced placental cell apoptosis could be mediated via the ADIPOR1-receptor in pre-eclampsia with IUGR

AIMS

Adiponectin and leptin are members of the adipocytokine family. Adiponectin promotes and leptin inhibits apoptosis and both are regulators of angiogenesis. Adipocytokines and their receptors are expressed in the placenta, and in the pre-eclamptic (PE) mother the serum levels of both are higher than in healthy ones. Our aim was to study the expression of adiponectin, leptin, their receptor genes and apoptosis in severely PE and normal placentas.

METHODS

The study group comprised 13 PE mothers and their 16 healthy controls. Placental biopsies were taken during cesarean section, the RNA was extracted and micro-array study was performed, followed by PCR and apoptosis studies.

RESULTS

The placental expression level of the leptin and adiponectin receptor 1 genes was significantly higher in PE mothers than in controls. No significant changes were observed in the levels of the adiponectin, adiponectin receptor 2 and Leptin receptor genes. The expression of the Adiponectin gene was low. The rate of apoptosis was higher in the PE placentas.

CONCLUSIONS

The activity of placental adipocytokines and their receptor genes in severe PE may suggest an important role in placental angiogenesis. Placental apoptosis induced by adiponectin could be mediated via the ADIPOR1-receptor.

Dysregulation of maternal serum adiponectin in preterm labor

OBJECTIVE

Intra-amniotic and systemic infection/inflammation have been causally linked to preterm parturition and fetal injury. An emerging theme is that adipose tissue can orchestrate a metabolic response to insults, but also an inflammatory response via the production of adipocytokines, and that these two phenomenons are interrelated. Adiponectin, an insulin-sensitising, anti-inflammatory adipocytokine, circulates in multimeric complexes including low-molecular weight (LMW) trimers, medium-molecular weight (MMW) hexamers and high-molecular weight (HMW) isoforms. Each of these complexes can exert differential biological effects. The aim of this study was to determine whether spontaneous preterm labor (PTL) with intact membranes and intra-amniotic infection/inflammation (IAI) is associated with changes in maternal serum circulating adiponectin multimers.

STUDY DESIGN

This cross-sectional study included patients in the following groups: (1) normal pregnant women (n=158); (2) patients with an episode of preterm labor and intact membranes without IAI who delivered at term (n=41); (3) preterm labor without IAI who delivered preterm (n=27); and (4) preterm labor with IAI who delivered preterm (n=36). Serum adiponectin multimers (total, HMW, MMW and LMW) concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

(1) Preterm labor leading to preterm delivery or an episode of preterm labor that does not lead to preterm delivery was associated with a lower median maternal serum concentration of total and HMW adiponectin, a lower median HMW/total adiponectin ratio and a higher median LMW/total adiponectin ratio than normal pregnancy; (2) among patients with preterm labor, those with IAI had the lowest median concentration of total and HMW adiponectin, as well as the lowest median HMW/total adiponectin ratio; (3) the changes in maternal adiponectin and adiponectin multimers remained significant after adjusting for confounding factors such as maternal age, BMI, gestational age at sampling and parity.

CONCLUSION

(1) Preterm labor is characterised by a change in the profile of adiponectin multimers concentrations and their relative isoforms. These changes were observed in patients with an episode of preterm labor not leading to preterm delivery, in patients with intra-amniotic inflammation, or in those without evidence of intra-amniotic inflammation. (2) The changes in adiponectin multimer concentrations reported in preterm labor are different from those previously reported in spontaneous labor at term, suggesting that there is a fundamental difference between preterm labor and labor at term. (3) The findings reported herein provide the first evidence for the participation of adiponectin multimer in preterm parturition. We propose that adiponectins and adipokines in general provide a mechanism to organise the metabolic demands generated by the process of preterm parturition regardless of the nature of the insult (intra-amniotic inflammation or not).

Serum Adiponectin Concentration Prior to Clinical Onset of Preeclampsia

OBJECTIVE

This study assesses whether the adipokine adiponectin is a useful marker in pregnant women who subsequently develop preeclampsia (PE).

METHODS

A retrospective case-control study was conducted to measure the total serum levels of adiponectin, measured by radioimmunoassay kit, in serum samples stored in serological biobanks.

RESULTS

Total serum adiponectin concentrations between the groups were not significantly different (p = 0.22). There were no obvious clinical signs of the preeclamptic inflammatory process at the time when samples were drawn.

CONCLUSION

Using this design, total adiponectin appeared not be a useful pre-clinical marker of PE.

Free fatty acid profiles in preeclampsia

Preeclampsia has many characteristics similar to the metabolic syndrome. One of these is aberrant lipid metabolism. We studied free fatty acid (FFA) profiles at baseline and after oral glucose load in 21 preeclamptic and 11 normotensive pregnant women. Insulin sensitivity was measured by intravenous glucose tolerance test. We found that serum total FFA concentrations at baseline were 67% higher in preeclamptic than in normotensive pregnancies (P=0.0002). The difference between the two groups was largest in the concentrations of oleic (75%), linoleic (129%) and arachidonic (315%) acids. Oral intake of glucose suppressed total FFA in preeclamptic women by 40% (95% CI 32.1-46.1%, P<0.0001) but only 24% in control women (95% CI 0.01-42.0%, P=0.045). Insulin sensitivity, which in preeclamptic women was 37% lower (P=0.009), was unrelated to total or any individual FFA concentration. We concluded that preeclamptic women have higher circulating FFA concentrations, which despite insulin resistance are suppressed by oral glucose loading.

Transition period-related changes in the abundance of the mRNAs of adiponectin and its receptors, of visfatin, and of fatty acid binding receptors in adipose tissue of high-yielding dairy cows

Adipose tissue expresses adipokines, which are involved in regulation of energy expenditure, lipid metabolism, and insulin sensitivity. To adapt for the transition from pregnancy to lactation, particularly in high-yielding dairy cows, adipokines, their receptors, and particular G-protein coupled receptors (GPRs) are of potential importance. Signaling by GPR 41 stimulates leptin release via activation by short-chain fatty acids; GPR 43/109A inhibits lipolysis, and GPR 109A thereby mediates the lipid-lowering effects of nicotinic acid and beta-hydroxybutyrate. The aim of this study was to compare the mRNA expression of adiponectin and visfatin, adiponectin receptors 1 and 2 (AdipoR1/2), leptin receptor (obRb), insulin receptor as of the aforementioned GPRs during the transition period in high-yielding dairy cows. Biopsies from subcutaneous fat and blood samples were obtained from 10 dairy cows 1 week before and 3 weeks after calving. For AdipoR1 and AdipoR2 mRNA abundance as well as for leptin concentrations in plasma, a reduction (P</=.05) was observed postpartum; for visfatin and putative GPR 109A mRNA abundance in adipose tissue, there was a trend (P<.1) for analogous changes. In contrast, the mRNA content of obRb and GPR 41 in adipose tissue was higher (P</=.05) in samples from early lactation than in those from late gestation. Our results indicate decreasing adiponectin sensitivity in adipose tissue after calving, which might be involved in the reduced insulin sensitivity of adipose tissue during early lactation. In addition, visfatin, GPR 41, and GPR 109A may further modulate insulin sensitivity.

Maternal serum adiponectin multimers in gestational diabetes

OBJECTIVE

Adiponectin, an adipokine with profound insulin-sensitizing effect, consists of heterogeneous species of multimers. These oligomeric complexes circulate as low-molecular-weight (LMW) trimers, medium-molecular-weight (MMW) hexamers and high-molecular-weight (HMW) isoforms and can exert differential biological effects. The aims of this study were to determine whether there is a change in circulating adiponectin multimers in the presence of gestational diabetes mellitus (GDM), overweight/obesity or with a treatment with sulfonylurea or insulin in patients with GDM.

STUDY DESIGN

This cross-sectional study included women with: 1) normal pregnancy (n=149); and 2) patients with GDM (n=72). Thirty-three patients with GDM were managed with diet alone. Among the others 39 diabetic patients, 17 were treated with Glyburide and 22 with insulin. The study population was further stratified by first trimester body mass index (BMI) (normal weight <25 kg/m(2) vs. overweight/obese > or =25 kg/m(2)). Serum adiponectin multimers (total, HMW, MMW and LMW) concentrations were determined by ELISA.

RESULTS

1) The median maternal serum of total, HMW, MMW and LMW were lower in patients with GDM than in those with normal pregnancies (P<0.001 for all comparisons); 2) patients with GDM had a lower HMW/total adiponectin ratio and a higher MMW/total and LMW/total adiponectin ratio than those with a normal pregnancy (P<0.001 for all comparisons); and 3) among GDM patients, there were no differences in the concentrations and relative distribution of adiponectin multimers between those who were managed with diet, and those who were treated with pharmacological agents.

CONCLUSION

1) GDM is characterized by a distinctive pattern of concentrations and relative distribution of adiponectin multimers akin to Type 2 diabetes mellitus; 2) dysregulation of adiponectin multimeres can provide a mechanistic basis for the association between adiposity and GDM.

Expressions of adiponectin receptors in placenta and their correlation with preeclampsia

BACKGROUND

Adiponectin and its receptors, adiponectin receptor 1 (Adipo-R1) and adiponectin receptor 2 (Adipo-R2), may contribute to preeclampsia; however, the reports up to date are conflicting. Here we further explore this issue.

METHODS

We studied 20 pregnant women with term normal pregnancy, 22 women with severe preeclampsia, and 12 mild cases. The levels of Adipo-Rs' protein and messenger RNA (mRNA) were detected by immunohistochemistry and real-time quantitative polymerized chain reaction (PCR) analysis, respectively.

RESULTS

The expression of Adipo-R2, but not Adipo-R1, was observed in the cytoplasm of both placental cytotrophoblasts and syncytiotrophoblasts of the mild preeclempsia, severe cases and normal pregnancy group. There was no significant difference of Adipo-R2 protein level between the maternal side and the fetal side in each group (all P > .05). Adipo-R2 protein and mRNA levels in severe preeclamptic group were significantly higher than those of mild cases (P < .001) and normal pregnancy group (P < .001). There was also no significant difference of Adipo-R2 protein and mRNA levels between term delivery and preterm delivery in severe preeclamptic group (P > .05). Nonetheless, both the protein and mRNA levels were significantly higher in comparison to those of the normal group (P < .05).

CONCLUSIONS

The abnormality of Adipo-R2 may be associated with the pathogenesis of preeclampsia.

Reviews: adipocytokines in normal and complicated pregnancies

Human pregnancy is characterized by insulin resistance, traditionally attributed to the effects of placental hormones. Normal pregnancy-induced insulin resistance is further enhanced in pregnancy complications, associated with disturbed placental function, such as gestational diabetes mellitus, preeclampsia, and intrauterine growth restriction. Compelling evidence suggests that these pregnancy disorders are associated with future development of maternal metabolic syndrome. However, the pathogenetic mechanisms underlying the association between abnormal placental development, insulin resistance, and maternal metabolic syndrome are not fully understood. A large body of evidence has recently supported the role of adipose tissue in the regulation of insulin resistance in both nonpregnant and pregnant participants. In this respect, adipocytokines, which are adipocyte-derived hormones, have been implicated in the regulation of maternal metabolism and gestational insulin resistance. Adipocytokines, including leptin, adiponectin, tumor necrosis factor alpha, interleukin 6, as well as the newly discovered resistin, visfatin, and apelin, are also known to be produced within the intrauterine environment. However, data concerning the pattern of adipocytokines secretion in normal and complicated pregnancies are still limited and partially contradictory. Given the importance of adipose tissue and its hormones in terms of adequate metabolic control and energy homeostasis, we present a review of published data related to the role of adipocytokines in pregnancy, especially in relation to pregnancy complications. Focus will be placed on the functions and other potential roles of the novel adipocytokines resistin, visfatin, and apelin.

Adiponectin multimers in maternal plasma

OBJECTIVE

Adiponectin is an anti-diabetic, anti-atherogenic, anti-inflammatory, and angiogenic adipokine that circulates in oligomeric complexes including: low molecular weight (LMW) trimers, medium molecular weight (MMW) hexamers, and high molecular weight (HMW) isoforms. The aim of this study was to determine whether there are changes in adiponectin multimers in pregnancy and as a function of maternal weight.

STUDY DESIGN

In this cross-sectional study, plasma concentrations of total, HMW, MMW, and LMW adiponectin were determined in women included in three groups: (1) normal pregnant women of normal body mass index (BMI) (n = 466), (2) overweight pregnant women (BMI >or=25; n = 257), and (3) non-pregnant women of normal weight (n = 40). Blood samples were collected once from each woman between 11 and 42 weeks of gestation. Plasma adiponectin multimer concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric statistics were used for analysis.

RESULTS

(1) The median HMW adiponectin concentration and the median HMW/total adiponectin ratio were significantly higher, and the median LMW adiponectin concentration was significantly lower in pregnant women than in non-pregnant women. (2) Among pregnant women, the median plasma concentration of total, HMW, and MMW adiponectin was significantly higher in normal weight women than in overweight patients. (3) Maternal HMW was the most prevalent adiponectin multimer regardless of gestational age or BMI status. (4) There were no significant differences in the median concentration of total, MMW, and LMW adiponectin and their relative distribution with advancing gestation.

CONCLUSION

Human pregnancy is characterized by quantitative and qualitative changes in adiponectin multimers, especially the most active isoform, HMW adiponectin.

Circulating and uteroplacental adipocytokine concentrations in preeclampsia

BACKGROUND

The adipokines adiponectin and leptin may contribute to preeclampsia; however, the reports are conflicting. We explored the issue further.

METHODS

We studied 25 pregnant women with normal pregnancy in first, 25 in second, and 30 in third trimesters, 15 healthy nonpregnant women, and 32 women with preeclampsia. We used enzyme-linked immunosorbent assay to measure human plasma adiponectin (ng/mL) and leptin (ng/mL) concentrations. We also investigated adiponectin and leptin expression by quantitative messenger RNA in fat, decidua, and placenta tissues in a second study.

RESULTS

Prepregnancy body mass index was not different in preeclamptic and nonpreeclamptic women. Plasma adiponectin concentrations increased throughout normal pregnancy, compared to nonpregnant women. The values increased in every trimester but were invariably lower in women with preeclampsia. Adiponectin nonetheless correlated inversely with prepregnancy body mass index. Such correlations were not found in women with preeclampsia. Plasma leptin in contrast decreased during pregnancy in every trimester. Leptin values were much higher in preeclamptic than in nonpreeclamptic women. Leptin expression was increased in the uteroplacental unit and in fat tissue of preeclamptic, compared to nonpreeclamptic women, while no differences in adiponectin expression were found.

CONCLUSIONS

Adiponectin increases in normal pregnancy but remains correlated with prepregnancy body mass index. Plasma leptin decreases in normal pregnancy. In preeclamptic women, the normal adipokine responses are perturbed and this could be of pathophysiological significance.

Maternal serum adiponectin multimers in preeclampsia

OBJECTIVE

Obesity, insulin resistance, and dyslipidemia are associated with preeclampsia. Recently, "adipose tissue failure", characterized by dysregulation of adipokine production, has been implicated in the pathophysiology of these metabolic complications. Adiponectin, an insulin-sensitizing, anti-atherogenic, anti-inflammatory and angiogenic adipokine, circulates in oligomeric complexes including: low-molecular-weight (LMW) trimers, medium-molecular-weight (MMW) hexamers and high-molecular-weight (HMW) isoforms. These multimers exert differential biological effects, and HMW to total adiponectin ratio (S(A)) has been reported to be a specific marker of adiponectin activity. The aim of this study was to determine whether preeclampsia is associated with changes in circulating adiponectin multimers.

STUDY DESIGN

This cross-sectional study included women with: 1) normal pregnancy (n=225); and 2) patients with mild preeclampsia (n=111). The study population was further stratified by first trimester BMI (normal weight <25 kg/m(2) vs. overweight/obese >or=25 kg/m(2)). Serum adiponectin multimers (total, HMW, MMW and LMW) concentrations were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

1) The median maternal HMW and LMW adiponectin concentrations were lower in patients with preeclampsia than in those with normal pregnancies (P<0.001 and P=0.01, respectively); 2) patients with preeclampsia had a lower HMW/total adiponectin ratio (P<0.001) and higher MMW/total adiponectin and LMW/total adiponectin ratios than those with a normal pregnancy (P<0.001 and P=0.009, respectively); 3) the presence of preeclampsia was independently associated with lower maternal serum HMW adiponectin concentrations (P=0.001) and with a low HMW/total adiponectin ratio (P<0.001) after correction for maternal age, maternal BMI, the difference in BMI between the third and the first trimester, and gestational age at sampling; and 4) overweight/obese pregnant women had a lower median total and HMW adiponectin concentration than normal weight pregnant women among women with normal pregnancies, but not among those with preeclampsia.

CONCLUSION

1) Preeclampsia is associated with a lower median concentration of the HMW adiponectin isoform, the most active form of this adipokine, and a low HMW/total adiponectin ratio, a specific marker of adiponectin biologic activity; 2) in contrast to normal pregnancy, preeclampsia is not associated with decreased circulating adiponectin multimers in overweight/obese individuals suggesting altered regulation of this adipokine in preeclampsia; 3) collectively, these findings suggest that preeclampsia is characterized by alterations in adiponectin multimers and their relative distribution implying a role for adiponectin multimers in the mechanism of disease in preeclampsia.

Maternal serum adiponectin multimers in patients with a small-for-gestational-age newborn

OBJECTIVE

Several mechanisms of disease have been implicated in the pathophysiology of small-for-gestational-age (SGA) including an anti-angiogenic state, and an exaggerated intravascular pro-inflammatory response. Adiponectin plays a role in a wide range of biological activities including those that have been implicated in the pathophysiology SGA. Thus, the aim of this study was to determine if third trimester adiponectin concentrations differed between women with normal weight infants and those with an SGA neonate.

STUDY DESIGN

This cross-sectional study included women with: 1) a normal pregnancy (n=234); and 2) an SGA neonate (n=78). SGA was defined as a birth weight below the 10th percentile for gestational age at birth. The study population was further stratified by first trimester body mass index (BMI) (normal weight <25 kg/m(2) vs. overweight/obese > or =25 kg/m(2)). Maternal serum adiponectin multimers [total, high-molecular-weight (HMW), medium-molecular-weight (MMW) and low-molecular-weight (LMW)] concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) The median maternal serum concentrations of total, HMW and MMW adiponectin were significantly lower in patients with an SGA neonate than in those with normal pregnancies; 2) patients with an SGA neonate had a significantly lower median HMW/total adiponectin ratio and higher median MMW/total adiponectin and LMW/total adiponectin ratios than those with a normal pregnancy; 3) among patients with an SGA neonate, neither maternal serum concentrations of adiponectin multimers, nor their relative distribution differ between normal weight and overweight/obese patients.

CONCLUSION

1) Pregnancies complicated by an SGA neonate are characterized by a alterations in the maternal serum adiponectin multimers concentrations and their relative abundance; 2) the findings reported herein suggest that maternal adipose tissue may play a role, in the pathogenesis of SGA.

Maternal visfatin concentration in normal pregnancy

OBJECTIVE

Adipose tissue has now emerged as a powerful endocrine organ via the production of adipokines. Visfatin, a novel adipokine with diabetogenic and immuno-modulatory properties has been implicated in the pathophysiology of insulin resistance in patients with obesity and Type-2 diabetes mellitus. The aim of this study was to determine whether there are changes in the maternal plasma concentration of visfatin with advancing gestation and as a function of maternal weight.

STUDY DESIGN

In this cross-sectional study, maternal plasma concentrations of visfatin were determined in normal weight and overweight/obese pregnant women in the following gestational age groups: 1) 11-14 weeks (n=52); 2) 19-26 weeks (n=68); 3) 27-34 weeks (n=93); and 4) >37 weeks (n=60). Visfatin concentrations were determined by ELISA. Non parametric statistics were used for analysis.

RESULTS

1) The median maternal plasma visfatin concentration was higher in pregnant women between 19-26 weeks of gestation than that of those between 11-14 weeks of gestation (P<0.01) and those between 27-34 weeks of gestation (P<0.01); 2) among normal weight pregnant women, the median plasma visfatin concentrations of women between 19-26 weeks of gestation was higher than that of those between 11-14 weeks (P<0.01) and those between 27-34 weeks (P<0.01); and 3) among overweight/obese patients, the median maternal visfatin concentration was similar between the different gestational age groups.

CONCLUSION

The median maternal plasma concentration of visfatin peaks between 19-26 and has a nadir between 27-34 weeks of gestation. Normal and overweight/obese pregnant women differed in the pattern of changes in circulating visfatin concentrations as a function of gestational age.

Maternal serum adiponectin multimers in gestational diabetes

OBJECTIVE

Adiponectin, an adipokine with profound insulin-sensitizing effect, consists of heterogeneous species of multimers. These oligomeric complexes circulate as low-molecular-weight (LMW) trimers, medium-molecular-weight (MMW) hexamers and high-molecular-weight (HMW) isoforms and can exert differential biological effects. The aims of this study were to determine whether there is a change in circulating adiponectin multimers in the presence of gestational diabetes mellitus (GDM), overweight/obesity or with a treatment with sulfonylurea or insulin in patients with GDM.

STUDY DESIGN

This cross-sectional study included women with: 1) normal pregnancy (n=149); and 2) patients with GDM (n=72). Thirty-three patients with GDM were managed with diet alone. Among the others 39 diabetic patients, 17 were treated with Glyburide and 22 with insulin. The study population was further stratified by first trimester body mass index (BMI) (normal weight <25 kg/m(2) vs. overweight/obese > or =25 kg/m(2)). Serum adiponectin multimers (total, HMW, MMW and LMW) concentrations were determined by ELISA.

RESULTS

1) The median maternal serum of total, HMW, MMW and LMW were lower in patients with GDM than in those with normal pregnancies (P<0.001 for all comparisons); 2) patients with GDM had a lower HMW/total adiponectin ratio and a higher MMW/total and LMW/total adiponectin ratio than those with a normal pregnancy (P<0.001 for all comparisons); and 3) among GDM patients, there were no differences in the concentrations and relative distribution of adiponectin multimers between those who were managed with diet, and those who were treated with pharmacological agents.

CONCLUSION

1) GDM is characterized by a distinctive pattern of concentrations and relative distribution of adiponectin multimers akin to Type 2 diabetes mellitus; 2) dysregulation of adiponectin multimeres can provide a mechanistic basis for the association between adiposity and GDM.

High molecular weight adiponectin dominates in cord blood of newborns but is unaffected by pre-eclamptic pregnancies

OBJECTIVE

This study is the first to report high molecular weight (HMW) adiponectin in newborns from normal and pre-eclamptic pregnancies (PE). Adiponectin is adversely related to Metabolic Syndrome-linked diseases such as obesity, dyslipidaemia, insulin resistance and hypertension. It is abundant in human plasma where it circulates as several characteristic multimeric forms of which the HMW form is the most active. As children from PE-pregnancies have a greater susceptibility to hypertensive disorders later in life, we hypothesized that adiponectin measured in cord blood could be a putative risk marker.

DESIGN AND PATIENTS

Cross-sectional, hospital-based study of newborns from mothers with pre-eclampsia (30 cases and 62 controls). Venous cord blood samples were collected immediately after birth and were analysed for total adiponectin and HMW adiponectin.

MEASUREMENTS

Total adiponectin and HMW adiponectin were measured by commercially available enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

The PE newborns showed a significantly lower gestational age (GA), total adiponectin and HMW adiponectin levels than the controls. No differences in adiponectin levels were found between case and control groups when correcting for GA. In combined groups, log (total adipo) = 0.40 + 0.027*GA; r = 0.43, P < 0.001. Furthermore, the HMW form is the dominant form of adiponectin: HMW adipo = -5.06 + 0.81*total adipo; r = 0.90, P < 0.001.

CONCLUSIONS

Adiponectin in cord blood from PE pregnancies may not be a tentative risk marker for Metabolic Syndrome-linked diseases. HMW adiponectin is the dominant form of adiponectin in cord blood. Its role during pregnancy and postnatal life should be further explored.

Activation of nuclear factor-kappaB by high molecular weight and globular adiponectin

Adipose tissue secretes a wide range of hormones named adipokines, and these may play a role in obesity-related inflammation. Adiponectin is an exceptional adipokine because low plasma concentrations are associated with obesity, type 2 diabetes, and cardiovascular diseases. It has been observed that plasma adiponectin concentrations are elevated during inflammatory conditions like preeclampsia and arthritis. Nuclear factor-kappaB (NF-kappaB) is an essential transcription factor for expression of inflammation-related proteins. We have used U937 cells stably transfected to express luciferase under the control of NF-kappaB to examine if adiponectin may modulate NF-kappaB activity. Physiological concentrations of native adiponectin induced NF-kappaB activity. This effect was relatively strong compared with proinflammatory adipokines like leptin, resistin, and IL-6. The enhanced NF-kappaB activity was attributed to the high molecular weight adiponectin isoforms. NF-kappaB was not activated by mutated adiponectin that is unable to form high molecular weight complexes. Furthermore, the C-terminal fragment, globular adiponectin, markedly increased NF-kappaB reporter activity, cytokine release, and mRNA expression of inflammation marker genes, at higher levels than stimulation with TNF-alpha and lipopolysaccharide. NF-kappaB activation by globular adiponectin was not affected by antibody inhibition of toll-like receptor 4 or TNF receptors 1 and 2 but was attenuated by inhibitors of p38 MAPK, phosphatidylinositol 3-kinase, and protein kinase C. Analyses of the p65 subunit of NF-kappaB in different leukocyte cell lines showed activation of two monocytic cell lines (U937 and THP-1) by native and globular adiponectin. Our results indicate that adiponectin has proinflammatory properties in monocytic cells.

Correlation between soluble endoglin, vascular endothelial growth factor receptor-1, and adipocytokines in preeclampsia

CONTEXT

Recent reports have demonstrated that soluble endoglin (sEng), an antiangiogenic protein thought to impair TGF-beta binding to receptors, and soluble vascular endothelial growth factor receptor (sVEGFR)-1 play important roles in the pathophysiology of preeclampsia (PE). Moreover, insulin resistance, which is greatly influenced by adipocytokines, characterizes PE.

OBJECTIVES

We examined possible links between sEng, VEGF, sVEGFR, and adipocytokines in the pathophysiology of PE.

STUDY DESIGN

We performed a cross-sectional study in 30 PE patients and controls matched for gestational age and body mass index. Blood samples were collected soon after disease onset. We measured serum concentrations of leptin, adiponectin, sEng, VEGF, placental growth factor (PlGF), and sVEGFR [soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble fetal liver kinase 1 (sFlk-1)], and examined the placental protein content of sEng and sFlt-1.

RESULTS

sEng concentrations in PE patients (60.9 +/- 28.8 ng/ml) were significantly higher than those in controls (11.2 +/- 4.4 ng/ml). There was a significant correlation between sEng and sFlt-1 or PlGF. Moreover, there were significant differences in mean blood pressure between the high and low sEng groups, and in proteinuria between the high and low sFlt-1 groups, and significant differences in placental sEng and sFlt-1 contents between patients with and without severe hypertension or proteinuria. sEng was also correlated positively with adiponectin levels and negatively with the leptin to adiponectin ratio.

CONCLUSIONS

Along with sFlt-1 and PlGF, sEng might play a role in the pathophysiology of PE, especially in elevating blood pressure, while the association with hypoadiponectinemia and the high leptin to adiponectin ratio in pregnancy seem to be risk factors for PE.

The role of adipocytokines in insulin resistance in normal pregnancy: visfatin concentrations in early pregnancy predict insulin sensitivity

BACKGROUND

Throughout pregnancy maternal adipose tissue is metabolically active, producing adipocytokines involved in the process of insulin resistance. We explored the role of serum adipocytokines, including the newly identified adipocytokine visfatin, in the process of insulin resistance in normal pregnancy.

METHODS

We examined 80 pregnant nonobese, nondiabetic white women during the 3 trimesters of pregnancy. All study participants underwent anthropometric measurements, adipocytokine evaluation, and a 75-g oral glucose tolerance test. Homeostasis mathematical model assessment (HOMA-R), insulin sensitivity index (ISI), and indices of beta-cell secretion were calculated.

RESULTS

Maternal weight, percentage total body fat, hip circumference, and indices of beta-cell secretion increased significantly during the 3 trimesters, and HOMA-R and ISI increased and decreased, respectively, in the 3rd trimester. During early pregnancy, insulin resistance, beta-cell secretion, and weight correlated positively with leptin. During the 1st trimester, visfatin correlated negatively with percentage body fat and was the best positive predictor of 2nd trimester ISI. In the 2nd trimester, serum visfatin was the best negative predictor of percentage body fat.

CONCLUSIONS

During normal pregnancy of nonobese, nondiabetic women, adipose tissue increases, accompanied by a significant progressive increase of insulin resistance. Visfatin concentrations in the 1st trimester positively predict insulin sensitivity during the 2nd trimester. Body fat mass during 1st trimester of pregnancy is negatively associated with insulin sensitivity during the 2nd trimester and perhaps should be kept under control.

Plasma adiponectin concentrations and placental adiponectin expression in pre-eclamptic women

This study was conducted to compare maternal plasma adiponectin concentrations and adiponectin expression in term placentas between normotensive pregnant women and pre-eclamptic women. Plasma adiponectin concentrations were assessed by a sandwich enzyme-linked immunosorbent assay in 81 normotensive pregnant women, 27 pre-eclamptic women and 15 non-pregnant healthy women. The expression of adiponectin in the placentas was assessed by immunohistochemistry. Plasma adiponectin concentrations in normotensive pregnant women did not show a significant change during pregnancy and postpartum compared with non-pregnant women. However, plasma adiponectin concentrations in pre-eclamptic women were significantly (p < 0.05) lower than in non-pregnant and normotensive pregnant women. No immunoreactive adiponectin was detected in the term placentas of normotensive pregnant women, whereas a positive immunostaining for adiponectin was observed in endothelial cells of chorionic vessels in pre-eclamptic women. Our data suggest that decreased plasma adiponectin concentrations may contribute to the pathophysiology of pre-eclampsia and that adiponectin localized in chorionic vessels may play a role in the restoring of endothelial damage in the feto-maternal units of pre-eclampsia.

Differential regulation of visfatin and adiponectin in pregnancies with normal and abnormal placental function

OBJECTIVE

There is compelling evidence that insulin resistance may play a pivotal role in the development of pregnancy complications including pre-eclampsia and intrauterine growth restriction (IUGR). As dysregulation of visfatin and adiponectin is found in insulin resistance, both adipokines might contribute to pregnancy disorders.

PATIENTS AND METHODS

Plasma levels of visfatin and adiponectin were quantified in second-trimester pregnancies with abnormal uterine perfusion and in third-trimester pregnancies with IUGR as compared to healthy controls.

RESULTS

Mean plasma adiponectin levels were significantly increased in women with pathological perfusion (7078 +/- 789 ng/ml) as compared to normal uterine perfusion (4481 +/- 1183 ng/ml) (P < 0.05) whereas visfatin plasma concentrations were not different between these groups. Visfatin levels were significantly elevated in women with IUGR (140.1 +/- 10 ng/ml) as compared to patients with normal outcome (65.5 +/- 11 ng/ml) (P < 0.05). By contrast, adiponectin plasma concentrations were not significantly altered in women with IUGR.

CONCLUSIONS

Our data support the view that the adipokines visfatin and adiponectin are differentially regulated in pregnancy complications.

Maternal serum adiponectin levels during human pregnancy

OBJECTIVE

Pregnancy is a unique situation characterized by insulin resistance. The role of adiponectin, an insulin-sensitizing hormone, has not been completely clarified during pregnancy. The aim of this cross-sectional study was to evaluate adiponectin levels during pregnancy and postpartum.

STUDY DESIGN

Adiponectin and leptin levels were tested in 80 pregnant women, 20 in each trimester (mean gestational age 10.5+/-1.9; 19.3+/-4.9; 39.3+/-0.8 weeks,) as well as 4 days postpartum.

RESULTS

Adiponectin levels during first (13.3+/-3.6 micro g/ml), second (12.6+/-4.4 micro g/ml) and third trimester (11.2+/-3.7 micro g/ml) did not differ and were significantly higher than postpartum levels (8.8+/-2.1 micro g/ml; P<0.0001, P<0.004 and P<0.02, respectively).

CONCLUSION

Despite increased insulin resistance during pregnancy, no significant alterations in adiponectin levels were observed. This may imply that the regulation of adiponectin during gestation is altered. The elevated gestational adiponectin levels are consistent with increased 'adiponectin resistance' during pregnancy.