Maternal plasma leptin is increased in preeclampsia and positively correlates with fetal cord concentration

The Role of Leptin in Fetal Growth during Pre-Eclampsia

Leptin is secreted by the placenta and has a multi-facetted role in the regulation of functions related to pregnancy. Metabolic disorders and insufficient homeostatic compensatory mechanisms involving leptin during pregnancy play a decisive role in the development of pre-eclampsia (PE) and give rise to compromised intrauterine growth conditions and aberrant birth weight of offspring. This review was compiled to elucidate the metabolic background of PE and its relationship with adverse intrauterine growth conditions through the examination of leptin as well as to describe possible mechanisms linking leptin to fetal growth restriction. This review illustrates that leptin in PE is dysregulated in maternal, fetal, and placental compartments. There is no single set of unifying mechanisms within the spectrum of PE, and regulatory mechanisms involving leptin are specific to each situation. We conclude that dysregulated leptin is involved in fetal growth at many levels through complex interactions with parallel pregnancy systems and probably throughout the entirety of pregnancy.

Impact of hyperleptinemia during placental ischemia-induced hypertension in pregnant rats

The prevalence of preeclampsia and obesity have increased. Although obesity is a major risk factor for preeclampsia, the mechanisms linking these morbidities are poorly understood. Circulating leptin levels increase in proportion to fat mass. Infusion of this adipokine elicits hypertension in nonpregnant rats, but less is known about how hyperleptinemia impacts blood pressure during placental ischemia, an initiating event in the pathophysiology of hypertension in preeclampsia. We tested the hypothesis that hyperleptinemia during reduced uterine perfusion pressure (RUPP) exaggerates placental ischemia-induced hypertension. On gestational day (GD) 14, Sprague-Dawley rats were implanted with osmotic mini-pumps delivering recombinant rat leptin (1 µg/kg/min iv) or vehicle concurrently with the RUPP procedure to induce placental ischemia or Sham. On GD 19, plasma leptin was elevated in Sham + Leptin and RUPP + Leptin. Leptin infusion did not significantly impact mean arterial pressure (MAP) in Sham. MAP was increased in RUPP + Vehicle vs. Sham + Vehicle. In contrast to our hypothesis, placental ischemia-induced hypertension was attenuated by leptin infusion. To examine potential mechanisms for attenuation of RUPP-induced hypertension during hyperleptinemia, endothelial-dependent vasorelaxation to acetylcholine was similar between Sham and RUPP; however, endothelial-independent vasorelaxation to the nitric oxide (NO)-donor, sodium nitroprusside, was increased in Sham and RUPP. These findings suggest that NO/cyclic guanosine monophosphate (cGMP) signaling was increased in the presence of hyperleptinemia. Plasma cGMP was elevated in Sham and RUPP hyperleptinemic groups compared with vehicle groups but plasma and vascular NO metabolites were reduced. These data suggest that hyperleptinemia during placental ischemia attenuates hypertension by compensatory increases in NO/cGMP signaling.NEW & NOTEWORTHY Ours is the first study to examine the impact of hyperleptinemia on the development of placental ischemia-induced hypertension using an experimental animal model.

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.

Therapeutic Prospects in Preeclampsia - A Mini-Review

BACKGROUND

Preeclapmsia (PE) is characterized by early onset symptoms such as elevated blood pressure, proteinuria and edema in the pregnant woman, and may result in seizures in the affected female. Currently, there are no therapeutic drugs available to treat this condition, but there are interventions to regulate the symptoms based on the gestational period of the fetus, although the largely favored option is delivery of the fetus and placenta.

OBJECTIVE

A search for biomolecules associated with PE was conducted so as to identify diagnostic markers and therapeutic leads.

RESULTS

The literature search resulted in the identification of biomolecules such as Corin and Placental Protein 13 (PP13), among others that are associated with PE. Thereby, giving an insight into the various mechanistic pathways involved in the causation of PE. However, it is also evident that PE cannot be solely attributed to any single mechanism but is due to an interplay of different factors that have led to the development of this disease condition.

CONCLUSION

The identified biomarkers would ultimately help in understanding this complex disease and perhaps lead to the discovery of potential effective molecular targets for clinical trials, thereby providing a valuable therapeutic option for affected pregnant women.

Obesity and High-Fat Diet Induce Distinct Changes in Placental Gene Expression and Pregnancy Outcome

Obese women are at high risk of pregnancy complications, including preeclampsia, miscarriage, preterm birth, stillbirth, and neonatal death. In the current study, we aimed to determine the effects of obesity on pregnancy outcome and placental gene expression in preclinical mouse models of genetic and nutritional obesity. The leptin receptor (LepR) null-reactivatable (LepRloxTB), LepR-deficient (Leprdb/+), and high-fat diet (HFD)-fed mice were assessed for fertility, pregnancy outcome, placental morphology, and placental transcriptome using standard quantitative polymerase chain reaction (qPCR) and qPCR arrays. The restoration of fertility of LepRloxTB was performed by stereotaxic delivery of adeno-associated virus-Cre into the hypothalamic ventral premammillary nucleus. Fertile LepRloxTB females were morbidly obese, whereas the wild-type mice-fed HFD showed only a mild increase in body weight. Approximately 80% of the LepRloxTB females had embryo resorptions (∼40% of the embryos). In HFD mice, the number of resorptions was not different from controls fed a regular diet. Placentas of resorbed embryos from obese mice displayed necrosis and inflammatory infiltrate in the labyrinth and changes in the expression of genes associated with angiogenesis and inflammation (e.g., Vegfa, Hif1a, Nfkbia, Tlr3, Tlr4). In contrast, placentas from embryos of females on HFD showed changes in a different set of genes, mostly associated with cellular growth and response to stress (e.g., Plg, Ang, Igf1, Igfbp1, Fgf2, Tgfb2, Serpinf1). Sexual dimorphism in gene expression was only apparent in placentas from obese LepRloxTB mice. Our findings indicate that an obese environment and HFD have distinct effects on pregnancy outcome and the placental transcriptome.

Markers of obesity and growth in preeclamptic and normotensive pregnant women

The objective of the study was to analyse leptin, IGF-1, Apo A, lipoproteins, haem oxygenase-1 (HO-1) in maternal sera and venous umbilical cord sera of newborn babies of 25 preeclamptics (group II), and 25 normotensive pregnant women (group I) as markers of obesity and growth in preeclamptic and normotensive pregnant women. Apo A I and II levels were estimated by competitive immunoassay using direct chemiluminiscence technology. Haem oxygenase-1 (HO-1), leptin and IGF-1 were analysed by ELISA. Maternal and cord blood levels of homocysteine, folic acid, lipid profile (namely, total cholesterol, triglycerides, LDL-C, VLDL-C and HDL-C), Haem oxygenase 1 were higher in preeclamptic women as compared to normotensive pregnant women. Serum and cord blood Apo A-I and Apo B, leptin levels, IGF-I were lower in preeclamptic women as compared to normotensive pregnant. The findings of high serum HO-1 levels in maternal and cord blood in preeclampsia supports the role of oxidative stress and excessive inflammatory response in the pathogenesis of preeclampsia. It seems likely that IGF-1 and leptin play a central role in controlling foetal growth. There is increasing evidence that the foundations of life-long health are, in part, laid in the uterus. Findings of present study suggest that alterations in biochemical markers of growth and obesity occur in mothers and foetuses and modifications of uterine environment can be of help to prevent future cardiovascular risk. Impact statement Preeclampsia has been reported to be associated with an increased risk of later life cardiovascular disease. However, information regarding how obesity increases the risk of preeclampsia is limited. Atherogenic milieu occurring during pregnancy persists into adulthood and foetal growth retardation is strongly associated with adult atherosclerosis. There is conflicting evidence regarding alterations of IGFs in preeclamptic pregnancies and deficit in circulating and cord blood IGF-1 levels in intrauterine growth restricted newborns and a correlation between IGF-1 levels and birth weight have been reported. Leptin is a predictor of cardiovascular risk independent of insulin resistance. Emerging evidence supports an important role for the haem oxygenase system (HO-1) in the maintenance of a healthy pregnancy, especially during pathological challenge. Conflicting data are available regarding HO-1, leptin and IGF -1 in preeclamptic mothers. The extent to which they mediate foetal growth and developmental abnormalities remains to be clarified. Serum IGF-1 levels were significantly decreased in preeclamptics and maternal IGF-1 showed a strong inverse correlation with leptin levels. High serum HO-1 levels in maternal and cord blood in preeclampsia were observed in the present study. Findings of the present study suggest that alterations in biochemical markers of growth and obesity occur in mothers and foetuses and modifications of the uterine environment can be of help to prevent future cardiovascular risk.

Uterine artery leptin receptors during the ovarian cycle and pregnancy regulate angiogenesis in ovine uterine artery endothelial cells†

Leptin regulates body weight, reproductive functions, blood pressure, endothelial function, and fetoplacental angiogenesis. Compared to the luteal phase, the follicular phase and pregnancy are physiological states of elevated estrogen, angiogenesis, and uterine blood flow (UBF). Little is known concerning regulation of uterine artery (UA) angiogenesis by leptin and its receptors. We hypothesized that (1) ex vivo expression of leptin receptors (LEPR) in UA endothelium (UAendo) and UA vascular smooth muscle (UAvsm) is elevated in pregnant versus nonpregnant (Luteal and Follicular) sheep; (2) in vitro leptin treatments differentially modulate mitogenesis in uterine artery endothelial cells from pregnant (P-UAECs) more than in nonpregnant (NP-UAECs) ewes; and (3) LEPR are upregulated in P-UAECs versus NP-UAECs in association with leptin activation of phospho-STAT3 signaling. Local UA adaptations were evaluated using a unilateral pregnant sheep model where prebreeding uterine horn isolation (nongravid) restricted gravidity to one horn. Immunolocalization revealed LEPR in UAendo and UAvsm from pregnant and nonpregnant sheep. Contrary to our hypothesis, western analysis revealed that follicular UAendo and UAvsm LEPR were greater than luteal, nongravid, gravid, and control pregnant. Compared to pregnant groups, LEPR were elevated in renal artery endothelium of follicular and luteal sheep. Leptin treatment significantly increased mitogenesis in follicular phase NP-UAECs and P-UAECs, but not luteal phase NP-UAECs. Although UAEC expression of LEPR was similar between groups, leptin treatment only activated phospho-STAT3 in follicular NP-UAECs and P-UAECs. Thus, leptin may play an angiogenic role particularly in preparation for the increased UBF during the periovulatory period and subsequently to meet the demands of the growing fetus.

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.

Preeclampsia As Modulator of Offspring Health

A balanced intrauterine homeostasis during pregnancy is crucial for optimal growth and development of the fetus. The intrauterine environment is extremely vulnerable to multisystem pregnancy disorders such as preeclampsia, which can be triggered by various pathophysiological factors, such as angiogenic imbalance, immune responses, and inflammation. The fetus adapts to these conditions by a mechanism known as developmental programming that can lead to increased risk of chronic noncommunicable diseases in later life. This is shown in a substantial number of epidemiological studies that associate preeclampsia with increased onset of cardiovascular and metabolic diseases in the later life of the offspring. Furthermore, animal models based predominantly on one of the pathophysiological mechanism of preeclampsia, for example, angiogenic imbalance, immune response, or inflammation, do address the susceptibility of the preeclamptic offspring to increased maternal blood pressure and disrupted metabolic homeostasis. Accordingly, we extensively reviewed the latest research on the role of preeclampsia on the offspring's metabolism and cardiovascular phenotype. We conclude that future research on the pathophysiological changes during preeclampsia and methods to intervene in the harsh intrauterine environment will be essential for effective therapies.

The Impact of Preeclampsia on Gene Expression at the Maternal-Fetal Interface

Preeclampsia (PE) impacts 8 million mother-infant pairs worldwide each year. This human pregnancy-specific disease characterized by hypertension and proteinuria accounts for significant maternal and neonatal morbidity and mortality. The current theory of the pathogenesis of PE as reviewed by Drs. Christopher Redman and Ian Sargent is thought to occur as a 2-stage process with poor placentation in the first half of pregnancy resulting in the maternal response in the second half of pregnancy. Our studies have focused on understanding the placental contribution to this serious disease by examining the gene expression profile of the deciduas basalis or basal plate, the region of the placenta involved in the "poor placentation". In this review we present summaries of our microarray datasets both of normal placentation and those gene expression changes resulting in the context of PE. Additionally, we have taken this opportunity to combine the data sets to provide a more comprehensive view of this region of the placenta. As defects in the basal plate are, in part, at the root of the disease process, we believe that understanding the pathobiology that occurs in this region will increase our ability to alter the development and/or course of PE.

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.

Transcriptomic analysis of human placenta in intrauterine growth restriction

BACKGROUND

Intrauterine growth restriction (IUGR) is a frequent complication of pregnancy defined as a restriction of fetal growth. The objective of this work was to improve the knowledge on the pathophysiology of IUGR using a genome-wide method of expression analysis.

METHODS

We analyzed differentially expressed genes in pooled placental tissues from vascular IUGR (four pools of three placentas) and normal pregnancies (four pools of three placentas) using a long nucleotide microarray platform (Nimblegen). We first did a global bioinformatics analysis based only on P value without any a priori. We secondly focused on "target" genes among the most modified ones. Finally, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed on an extended panel of tissue samples (n = 62) on selected "target".

RESULTS

We identified 636 modified genes among which 206 were upregulated (1.5 and higher; P < 0.05). Groups of patients were classified unambiguously. Genes involved in mitochondrial function and oxidative phosphorylation were decreased affecting three out of five complexes of the respiratory chain of the mitochondria, and thus energy production and metabolism. Among the most induced genes, we identified LEP, IGFBP1, and RBP4.

CONCLUSION

Complementary studies on the role and function of LEP, IGFBP1, and RBP4 in IUGR pathophysiology and also in fetal programming remain necessary.

Obesity and low-grade inflammation increase plasma follistatin-like 3 in humans

BACKGROUND

Rodent models suggest that follistatin-like 3 (fstl3) is associated with diabetes and obesity. In humans, plasma fstl3 is reduced with gestational diabetes. In vitro, TNF-α induces fstl3 secretion, which suggests a link to inflammation.

OBJECTIVE

To elucidate the association between plasma fstl3 and obesity, insulin resistance, and low-grade inflammation in humans.

STUDY DESIGN

Plasma fstl3 levels were determined in a cross-sectional study including three groups: patients with type 2 diabetes, impaired glucose tolerance, and healthy controls. In addition, lipopolysaccharide (LPS), TNF-α, or interleukin-6 (IL-6) as well as a hyperinsulinemic euglycemic clamp were used to examine if plasma fstl3 was acutely regulated in humans.

RESULTS

Plasma fstl3 was increased in obese subjects independent of glycemic state. Moreover, plasma fstl3 was positively correlated with fat mass, plasma leptin, fasting insulin, and HOMA B and negatively with HOMA S. Furthermore plasma fstl3 correlated positively with plasma TNF-α and IL-6 levels. Infusion of LPS and TNF-α, but not IL-6 and insulin, increased plasma fstl3 in humans.

CONCLUSION

Plasma fstl3 is increased in obese subjects and associated with fat mass and low-grade inflammation. Furthermore, TNF-α increased plasma fstl3, suggesting that TNF-α is one of the inflammatory drivers of increased systemic levels of fstl3.

Leptin and leptin receptor polymorphisms and recurrent pregnancy loss

OBJECTIVE

Leptin signaling is important in the establishment of pregnancy. We sought to determine if single nucleotide polymorphisms (SNPs) in the leptin and leptin receptor genes are associated with idiopathic recurrent pregnancy loss (RPL).

STUDY DESIGN

We conducted a case-control study with cases defined as women with idiopathic RPL and controls as parous women without pregnancy losses. A total of 99 cases and 108 controls were genotyped for the leptin (-2548 G/A) SNP and the leptin receptor A223G SNP. Genotype and allele frequencies were compared between cases and controls using χ(2) test.

RESULT

In this population, there was no significant difference in the genotype or allele frequencies for the leptin (-2548 G/A) or leptin receptor A223G SNPs between women with idiopathic RPL and controls.

CONCLUSION

Although leptin signaling is critical to many aspects of reproduction, the maternal leptin and leptin receptor SNPs evaluated in this study are unlikely to have a clinically meaningful role in RPL.

Biomarkers in pre-eclampsia: a novel approach to early detection of the disease

Pre-eclampsia is a unique disorder of human pregnancy with a great impact on maternal and perinatal morbidity and mortality worldwide and especially in developing countries. The aetiology is still unknown and the pathophysiology of the disease is the subject of extensive investigation. Recently, much of the interest of the investigators for the prediction of pre-eclampsia has been aimed at measurable manifestations of abnormal placentation, endothelial dysfunction and feto-maternal unit perfusion. Biomarkers constitute a novel approach to an early detection of the disease. Low maternal serum levels of PAPP-A and PP13 early in pregnancy are predictive for emerging pre-eclampsia. On the other hand, increased levels of homocysteine, ADMA, sEng, leptin and sFlt-1 in the 1st trimester, signal the onset of the disease later in pregnancy. After the onset of pre-eclampsia, increased serum levels of PAPP-A, ADMA, homocysteine and sFlt-1 are associated with the severity of the disease. The identification of biomarkers which can contribute to the early detection of pre-eclampsia is essential. It could then be possible to apply better surveillance and treatment protocols in such patients.

Maternal and fetal leptin, adiponectin levels and associations with fetal insulin sensitivity

OBJECTIVE

It remains uncertain whether leptin and adiponectin levels are correlated in maternal vs. fetal circulations. Little is known about whether leptin and adiponectin affect insulin sensitivity during fetal life.

DESIGN AND METHODS

In a prospective singleton pregnancy cohort (n = 248), we investigated leptin and adiponectin concentrations in maternal (at 24-28 and 32-35 weeks of gestation) and fetal circulations, and their associations with fetal insulin sensitivity (glucose/insulin ratio, proinsulin level).

RESULTS

Comparing concentrations in cord vs. maternal blood, leptin levels were 50% lower, but adiponectin levels more than doubled. Adjusting for gestational age at blood sampling, consistent and similar positive correlations (correlation coefficients: 0.31-0.34, all P < 0.0001) were observed in leptin or adiponectin levels in maternal (at 24-28 or 32-25 weeks of gestation) vs. fetal circulations. For each SD increase in maternal plasma concentration at 24-28 weeks, cord plasma concentration increased by 12.7 (95% confidence interval 6.8-18.5) ng/ml for leptin, and 2.9 (1.8-4.0) µg/ml for adiponectin, respectively (adjusted P < 0.0001). Fetal insulin sensitivity was negatively associated with cord blood leptin (each SD increase was associated with a 5.4 (2.1-8.7) mg/dl/µU/ml reduction in cord plasma glucose/insulin ratio, and a 5.6 (3.9, 7.4) pmol/l increase in proinsulin level, all adjusted P < 0.01) but not adiponectin (P > 0.4) levels). Similar associations were observed in nondiabetic full-term pregnancies (n = 211).

CONCLUSIONS

The results consistently suggest a maternal impact on fetal leptin and adiponectin levels, which may be an early life pathway in maternal-fetal transmission of the propensity to obesity and insulin resistance.

LEPR c.668A>G polymorphism in a cohort of Sri Lankan women with pre-eclampsia / pregnancy induced hypertension: a case control study

Background

Leptin is known to be elevated in pre-eclampsia/ pregnancy induced hypertension (PE/PIH). However the reports on the association of leptin receptor (LEPR) c.668A>G polymorphism with PE/PIH are inconsistent.

Findings

LEPR c.668A>G polymorphism was studied in a cohort of women with PE/PIH (N = 61) and normotensive pregnancies (N = 40) by polymerase chain reaction / restriction fragment length polymorphism. Genotype and allele frequencies were in Hardy-Weinberg equilibrium within both groups (Chi square test). Allele and genotype frequencies were not significantly different between PE/PIH and normotensive pregnancies (Chi square test). Leptin levels (Kruskal Wallis analysis of variance) and leptin/body mass index (one way analysis of variance) were not significantly different between genotypes within each group. However, leptin (Mann Whitney U test) and leptin normalised to body mass index (unpaired t test) were significantly higher in PE/PIH women homozygous and heterozygous for the G668 allele than in respective normotensives.

Conclusions

Whether the leptin receptor c.668A>G polymorphism increases the risk of developing PE/PIH in Sri Lankan women remains inconclusive in view of the smaller sample studied. However leptin levels in PE/PIH appeared to be modulated by this polymorphism.

Comparative gene expression profiling of placentas from patients with severe pre-eclampsia and unexplained fetal growth restriction

BACKGROUND

It has been well documented that pre-eclampsia and unexplained fetal growth restriction (FGR) have a common etiological background, but little is known about their linkage at the molecular level. The aim of this study was to further investigate the mechanisms underlying pre-eclampsia and unexplained FGR.

METHODS

We analyzed differentially expressed genes in placental tissue from severe pre-eclamptic pregnancies (n = 8) and normotensive pregnancies with or (n = 8) without FGR (n = 8) using a microarray method.

RESULTS

A subset of the FGR samples showed a high correlation coefficient overall in the microarray data from the pre-eclampsia samples. Many genes that are known to be up-regulated in pre-eclampsia are also up-regulated in FGR, including the anti-angiogenic factors, FLT1 and ENG, believed to be associated with the onset of maternal symptoms of pre-eclampsia. A total of 62 genes were found to be differentially expressed in both disorders. However, gene set enrichment analysis for these differentially expressed genes further revealed higher expression of TP53-downstream genes in pre-eclampsia compared with FGR. TP53-downstream apoptosis-related genes, such as BCL6 and BAX, were found to be significantly more up-regulated in pre-eclampsia than in FGR, although the caspases are expressed at equivalent levels.

CONCLUSIONS

Our current data indicate a common pathophysiology for FGR and pre-eclampsia, leading to an up-regulation of placental anti-angiogenic factors. However, our findings also suggest that it may possibly be the excretion of these factors into the maternal circulation through the TP53-mediated early-stage apoptosis of trophoblasts that leads to the maternal symptoms of pre-eclampsia.

Maternal leptin and body composition in the first trimester of pregnancy

BACKGROUND

Leptin is produced mainly by adipocytes. Levels are increased in women with obesity and during pregnancy. Increased levels are also associated with pregnancy complications such as, pre-eclampsia and gestational diabetes mellitus.

OBJECTIVE

We studied what component of body composition correlated best with maternal leptin in the first trimester of pregnancy and, whether maternal leptin correlated better with visceral fat rather than fat distributed elsewhere.

SUBJECTS AND METHODS

Women were recruited in the first trimester. Maternal adiposity was measured using body mass index and advanced bioelectrical impedance analysis. Maternal leptin was measured using an enzyme-linked immunosorbent assay technique.

RESULTS

Of the 100 subjects studied, the mean leptin concentration was 37.7 ng/ml (range: 2.1-132.8). Leptin levels did not correlate with gestational age in the first trimester, maternal age, parity or birth weight. Serum leptin correlated positively with maternal weight and body mass index, and with the different parameters of body composition. On multiple regression analysis, serum leptin correlated with visceral fat but not fat distributed elsewhere.

CONCLUSIONS

Visceral fat is the main determinant of circulating maternal leptin in the first trimester of pregnancy. This raises the possibility that maternal leptin in early pregnancy may be a marker for the development of metabolic syndrome, including diabetes mellitus.

Association of -2548 G/A polymorphism in the leptin gene with preeclampsia/pregnancy-induced hypertension

OBJECTIVES

To investigate −2548 G/A polymorphism of LEP gene, plasma leptin and soluble leptin receptor in preeclampsia/pregnancy induced hypertension.

METHODS

Sixty-two patients and 63 controls (normal pregnancies) studied in the third trimester. Leptin and soluble leptin receptor measured by enzyme immunosorbent assay and −2548 G/A polymorphism by polymerase chain reaction followed by restriction enzyme digestion.

RESULTS

Frequency of the AA genotype was significantly (p < 0.001) higher in patients. The A allele conferred a relative risk of 1.67 for the disease (p < 0.0001). Preeclampsia/pregnancy induced hypertension significantly (p < 0.001 to 0.0001) affected leptin and soluble leptin receptor concentrations, free leptin index and leptin normalized to body mass index. Genotype significantly (p < 0.05) influenced only the soluble leptin receptor concentrations.

CONCLUSIONS

Preeclampsia/pregnancy induced hypertension appears to be associated with higher circulating leptin and lower SLR levels, and with the AA genotype of −2548 G/A polymorphism of the leptin gene.

Upregulation of leptin-receptor in placental cells by hypoxia

OBJECTIVE

Leptin and its receptor (Ob-R) are co-expressed in human placenta suggesting auto- and paracrine mechanisms of the hormone. So far it is unclear, how changes in the placental environment affect Ob-R expression. Hence, the main purpose of the study was to investigate leptin receptor expression and regulation under hypoxic conditions. The influences of hypoxia and leptin on signal transduction and cell proliferation in chorioncarcinoma cell lines as well as primary villous trophoblasts were determined.

RESULTS

We found a time-dependent induction of leptin receptor mRNA and protein in placental cells under hypoxic conditions. In contrast, soluble leptin receptor expression did not change under oxygen deprivation. Leptin treatment neither activated the p42/p44 nor the STAT3 pathway in placental cells, being independent of hypoxic or normoxic conditions. Furthermore, leptin added to the culture medium in high concentrations was unable to interfere with the rate of proliferation.

CONCLUSION

Our data demonstrate that hypoxia leads to an increase of Ob-R expression in placental cells. Interestingly, leptin-dependent signal transduction and proliferation remained unaffected. A possible role of the soluble leptin receptor in modulating free leptin levels will be discussed.

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.

Microarray analysis of placental tissue in intrauterine growth restriction

OBJECTIVE

Besides foetal or maternal disorders, placental dysfunction is a major cause of intrauterine growth restriction (IUGR). Although numerous macro- and histopathological changes have been described, little is known about the precise aetiology and the contribution of foetal/placental genes in this disorder.

DESIGN

Placental tissues of 20 IUGR and control neonates were analysed by microarray technique. Four of the regulated genes with possible relevance in the pathogenesis of IUGR and its consequences were further studied in placentas of 27 IUGR and 35 control newborns.

RESULTS

Elevated gene expression of leptin, corticotrophin-releasing hormone (CRH), and IGF-binding protein-1 (IGFBP-1) in IUGR placentas could be confirmed in the larger group by real-time PCR, whereas prolactin showed no significant difference. Accordingly, protein expression of leptin and IGFBP-1 depicted by Western blot was elevated in IUGR, prolactin was not different. Birthweight standard deviation score (SDS) correlated negatively to leptin, IGFBP-1, and CRH, whereas placental weight correlated only to IGFBP-1. Leptin correlated negatively to gestational age of IUGR patients and positively to placental score, a marker of severity of impaired foeto-placental circulation.

CONCLUSIONS

As confirmed in a large group of IUGR and control samples, the up-regulated factors leptin, IGFBP-1, and CRH may serve as candidate genes for the prediction of subsequent metabolic consequences in IUGR newborns. These three factors may not only influence growth of the foetus, but might also interact with programming of its metabolic functions, which has to be determined in an ongoing study.

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).

Leptin in first trimester pregnancy serum: no reduction associated with small-for-gestational-age infants

Leptin is an adipocytokine that is also synthesized by the placenta. Leptin and its receptor, which is also expressed by the placenta, are believed to play an auto- and paracrine role in trophoblast invasion and placental development. The leptin concentration in first trimester maternal serum and its relation to fetal growth disturbances were examined in this study. The study is a case-control study with 36 small-for-gestational-age (SGA) (<5th percentile) pregnancies and 108 appropriate-for-gestational-age (AGA) (> or =5th percentile) pregnancies. The groups were matched by maternal age, gestational age and body mass index (BMI). All were non-smokers. Leptin was measured in maternal serum in weeks 8-13 and was normalized for BMI with concentrations expressed as multiples of the median for the actual BMI. It was found that maternal serum leptin increased strongly (r = 0.7, P < 10(-4))with maternal BMI. There was no significant difference in maternal serum leptin concentrations between SGA and AGA pregnancies. In conclusion, SGA pregnancies are not associated with a lower maternal serum leptin concentration in first trimester. The maternal serum leptin concentration is largely determined by maternal BMI. Variation in the leptin concentration in maternal serum in first trimester does not seem to be associated with impaired fetal growth.

Insulin resistance: the possible link between gestational diabetes mellitus and hypertensive disorders of pregnancy

Gestational hypertension, preeclampsia, and diabetes are all associated with increased risks of poor maternal and perinatal outcomes. Pregnant women with gestational diabetes have been shown in population studies to have increased risk of pregnancy-associated hypertension compared with nondiabetic women. Moreover, pregnant patients with hypertension are at increased risk for developing gestational diabetes mellitus. It has been hypothesized that this association could be due, at least in part, to insulin resistance. Although insulin resistance is a physiologic phenomenon in normal pregnancy, in predisposed individuals this could lead to hyperinsulinemia with the development of gestational hypertension, gestational diabetes mellitus, or both.

Raised Leptin Concentrations in Feto-Placental Tissues from Women with Preeclampsia

OBJECTIVE

The aim of this study was to estimate the levels of leptin in the amnion, chorion laeve, and placenta and to examine for any differences in leptin levels in these tissues from preeclamptic and normotensive pregnant women.

METHOD

Fresh samples of amnion, chorion laeve, and placenta were obtained from 10 normotensive and 10 preeclamptic women following vaginal delivery. After repeated washing with Krebs Heinsleit solution, 2 g of each tissue were homogenized separately. Following centrifugation, the supernatant was removed and stored at -80 degrees C for analysis of leptin at a later date. Leptin in supernatants from homogenates was measured using commercially available radioimmunoassay (RIA) Kits. Statistical analysis was performed using student's t-test for independent samples and all results are expressed as mean +/- SEM.

RESULTS

Leptin concentrations were significantly higher in all the three tissues from preeclamptic women when compared to the corresponding tissues from normotensive controls (0.52 +/- 0.1 vs. 1.15 +/- 0.41; 0.99 +/- 0.16 vs. 2.19 +/- 0.71; and 10.28 +/- 1.06 vs. 13.95 +/- 1.13 in the amnion, chorion laeve, and placenta, respectively, from normotensive pregnant women and women with preeclampsia; p < 0.05).

CONCLUSION

Leptin concentration is significantly raised in fetoplacental tissues from women with preeclampsia. Its role in preeclampsia remains unclear and it is not possible to say from this study if the raised levels of leptin evident in placentas from preeclamptic women are a cause or consequence of preeclampsia, although the latter seems more likely.

Predicting Transformation from Gestational Hypertension to Preeclampsia in Clinical Practice: A Possible Role for 24 Hour Ambulatory Blood Pressure Monitoring

OBJECTIVE

To identify parameters that may assist clinicians in predicting which women will develop preeclampsia (PE) after initially presenting with gestational hypertension (GH).

METHODS

118 women were recruited to the study with GH or PE. They were divided into three groups based on their diagnosis at delivery- (1) GH, (2) PE from the time of presentation, (3) those with an initial diagnosis of GH who progressed to PE. Women underwent 24 hour ambulatory blood pressure monitoring (ABPM) and had serum estrogen, progesterone, beta-HCG, leptin and adiponectin measured as possible predictors of transformation of GH to PE.

RESULTS

Women who presented with GH, and progressed to PE, presented four weeks earlier (33 vs 37 weeks, p < 0.001) than those who did not progress. Women with PE, either as their initial diagnosis or after progression from GH, were delivered earlier (p < 0.001) and had more small for gestational age (SGA) babies than women with GH at delivery (p < 0.05). Those who developed PE after presenting with GH generally had higher blood pressures than those who remained as GH, significant for awake and 24 hour systolic blood pressures (p < 0.05). beta-HCG, estrogen, progesterone or leptin values were similar across the groups. Adiponectin was higher in women with established PE at presentation compared to women with GH (p = 0.02) but adiponectin failed to discriminate those women with an initial diagnosis of GH who progressed to PE.

CONCLUSION

24 hr ABPM may provide a non-invasive method of identifying this 'at risk' GH population, particularly in the case of early presentation.

Markers for Presymptomatic Prediction of Preeclampsia and Intrauterine Growth Restriction

Preeclampsia and intrauterine growth restriction are both characterized by placental malfunction. The pathological processes of abnormal trophoblast invasion, partial absence of maternal spiral artery modification, increased apoptosis of trophoblast cells, and placental ischemia are all associated with the release of specific molecules. These proteins, as well as cell-free fetal DNA and RNA might be detected in the maternal peripheral circulation, quantified, and used for early identification and prediction of preeclampsia and intrauterine growth restriction, prior to the appearance of the clinical symptoms. As preeclampsia and intrauterine growth restriction are associated with increased maternal, perinatal, and neonatal morbidity and mortality, early identification of these pregnancy associated complications will permit the design of appropriate preventive measures. In this review a variety of factors reported to be useful as potential markers for early detection of pregnancies at increased risk will be discussed. Molecules associated with the establishment of the placenta and essential in fetal-maternal interactions, like interleukin 2-receptor, insulinlike growth factor-1, and insulinlike growth factor binding protein-1, placenta growth factor, hepatocyte growth factor, inhibin A, activin A, and human chorionic gonadotrophin seem to be the most likely candidates for presymptomatic markers for preeclampsia and/or intrauterine growth restriction. Detection and discrimination of these molecules through the placental RNA in maternal plasma based strategy has become a realistic option.

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.

Leptin affects system A amino acid transport activity in the human placenta: evidence for STAT3 dependent mechanisms

BACKGROUND

Amino acids are important nutrients during fetal development, and the activity of placental amino acid transporters is crucial in the regulation of fetal growth. Leptin, an adipocyte- and placenta-derived hormone, has been proposed to act as a peripheral signal in reproduction in humans. Leptin is elevated during pregnancy and elevated further in pathologic pregnancies such as preeclampsia. However, the role of leptin in placental function has not been fully elucidated. We hypothesize that leptin plays a role in the regulation of placental amino acid transport by activation of the JAK-STAT pathway.

METHODS

Placental amino acid transport, specifically system A transport was studied in placental villous fragments using the amino acid analog, methylaminoisobutyric acid (MeAIB). Specific inhibitors of the JAK-STAT signal transduction pathway were used to further elucidate their role in leptin-mediated effects on amino acid transport activity. Western blotting was performed to identify STAT3 phosphorylation as a measure of leptin receptor activation.

RESULTS

Leptin significantly increased system A amino acid transporter activity by 22-42% after 1h of incubation. Leptin activated JAK-STAT signaling pathway as evidenced by STAT3 phosphorylation, and inhibition of STAT3 or JAK2 resulted in 36-45% reduction in system A amino acid transporter activity. Furthermore, blocking endogenously produced leptin also decreased system A transport by 45% comparable to STAT3 inhibition.

CONCLUSIONS

These data demonstrate that leptin stimulates system A by JAK-STAT dependent pathway in placental villous fragments. Our findings support the autocrine/paracrine role of leptin in regulating amino acid transport in the human placenta.

Severe preeclampsia-related changes in gene expression at the maternal-fetal interface include sialic acid-binding immunoglobulin-like lectin-6 and pappalysin-2

Preeclampsia (PE), which affects 4-8% of human pregnancies, causes significant maternal and neonatal morbidity and mortality. Within the basal plate, placental cytotrophoblasts (CTBs) of fetal origin invade the uterus and extensively remodel the maternal vasculature. In PE, CTB invasion is often shallow, and vascular remodeling is rudimentary. To better understand possible causes, we conducted a global analysis of gene expression at the maternal-fetal interface in placental samples from women with PE (n = 12; 24-36 wk) vs. samples from women who delivered due to preterm labor with no evidence of infection (n = 11; 24-36 wk), a condition that our previous work showed is associated with normal CTB invasion. Using the HG-U133A&B Affymetrix GeneChip platform, and statistical significance set at log odds-ratio of B >0, 55 genes were differentially expressed in PE. They encoded proteins previously associated with PE [e.g. Flt-1 (vascular endothelial growth factor receptor-1), leptin, CRH, and inhibin] and novel molecules [e.g. sialic acid binding Ig-like lectin 6 (Siglec-6), a potential leptin receptor, and pappalysin-2 (PAPP-A2), a protease that cleaves IGF-binding proteins]. We used quantitative PCR to validate the expression patterns of a subset of the genes. At the protein level, we confirmed PE-related changes in the expression of Siglec-6 and PAPP-A2, which localized to invasive CTBs and syncytiotrophoblasts. Notably, Siglec-6 placental expression is uniquely human, as is spontaneous PE. The functional significance of these novel observations may provide new insights into the pathogenesis of PE, and assaying the circulating levels of these proteins could have clinical utility for predicting and/or diagnosing PE.

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.

Leptin and its metabolic interactions: an update

Obesity results from an abnormal accumulation of fat in the white adipose tissue. Recent research utilizing genetic models of obesity in rodents has implicated a major role of leptin as a controller of obesity. Leptin is a 167-amino acid peptide hormone encoded by the obesity gene (ob), which is secreted by adipocytes and plays an important role in regulating food intake, energy expenditure and adiposity. Leptin receptors (OB-R) are expressed in the central nervous system mainly in afferent satiety centres of hypothalamus and in peripheral organs such as adipose tissues, skeletal muscles, pancreatic beta-cells and liver, thus indicating the autocrine and paracrine role of leptin in energy regulation. In human beings, a highly organized circadian pattern of leptin secretion is observed with peak levels in the midnight probably resulting from cumulative hyperinsulinemia of entire day. Leptin has a dual role in weight maintenance. Leptin reflects total body adipose tissue mass whereas in conditions of negative and positive energy balance, the dynamic changes in plasma leptin concentration function as a sensor of energy balance and influence the efferent energy regulation pathways. Many effects of leptin on metabolism are mediated by interaction with Insulin and also by synergistic action with cholecystokinin. Besides physiological roles, leptin may influence pathological conditions like obesity-associated atherosclerosis, oxidative stress and cancers. The purpose of the present review is to summarize the important aspects of the biology, actions, and regulation of leptin and to serve as an update of new information.

Increased levels of pregnancy-associated plasma protein-A2 in the serum of pre-eclamptic patients

Pregnancy-associated plasma protein-A and -A2 (PAPP-A and -A2) are proteases that cleave insulin-like growth factor-binding proteins (IGFBPs), resulting in local activation of IGF signaling pathways. Here, we examined PAPP-A and -A2 mRNA and protein levels in placenta and maternal sera from women with pre-eclampsia and compared them with samples from uncomplicated pregnancy. PAPP-A2 but not PAPP-A mRNA and protein were elevated in pre-eclamptic placenta (P < 0.01). PAPP-A2 is normally produced in placental syncytiotrophoblast cells and maternal decidua. PAPP-A2 in syncytiotrophoblast cells was dramatically increased in pre-eclampsia. Maternal serum concentrations of PAPP-A2 but not PAPP-A were also significantly elevated in pre-eclampsia as compared with uncomplicated pregnancy. mRNA levels of IGFBP5, a specific substrate for PAPP-A2 protease activity, were also significantly increased, suggesting a potential role for IGFBP5 in fetal and placental growth suppression during pre-eclampsia. However, IGFBP5 protein levels were not increased in placenta from pre-eclampsia, possibly due to cleavage by up-regulated PAPP-A2. These data might imply that PAPP-A2 may be up-regulated in pre-eclamptic pregnancy to compensate for IGFBP5-mediated suppression of the IGF pathway, although final birthweights are still low in pre-eclamptic pregnancy.

Serum leptin and ghrelin concentrations of maternal serum, arterial and venous cord blood in healthy and preeclamptic pregnant women

Preeclampsia, a common complication of pregnancy, is associated with alteration in the concentration of leptin in maternal blood. The action of leptin is antagonistic to that of ghrelin. Here, we compared the levels of leptin and ghrelin in maternal serum and in arterial and venous cord blood between healthy pregnant women and those suffering from mild and severe preeclampsia. The levels of leptin in maternal and newborn's blood were elevated in both mild and severe preeclamptic patients (p < 0.05). Moreover, serum ghrelin levels were negatively correlated with blood pressure and leptin/ghrelin ratio was decreased in preeclampsia (p < 0.05). We concluded that increased production of ghrelin may represent a compensatory hypotensive mechanism in preeclamptic women.

Fetal responses during placental malaria modify the risk of low birth weight

Inflammation during placental malaria (PM) is associated with low birth weight (LBW), especially during the first pregnancy, but the relative contribution of maternal or fetal factors that mediate this effect remains unclear and the role of gamma interferon (IFN-gamma) has been controversial. We examined the relationship of maternal and cord plasma levels of IFN-gamma, tumor necrosis factor alpha, interleukin-10, ferritin, and leptin to birth weight for Tanzanian women delivering in an area where there is a high rate of malaria transmission. The placental levels of inflammatory cytokines, including IFN-gamma, increased significantly during PM in primigravid and multigravid women but not in secundigravid women. PM also increased maternal peripheral levels of all inflammatory markers except IFN-gamma but had strikingly little effect on cord levels of these proteins. In a multivariate analysis, placental IFN-gamma was negatively associated (P = 0.01) and cord ferritin was positively associated (P < 0.0001) with birth weight in infected (PM-positive [PM+]) first-time mothers. This relationship was not observed in other mothers, consistent with the epidemiology of PM and disease. Cord leptin had a strong positive relationship with birth weight in offspring of PM-negative women (P = 0.02 to P < 0.0001) but not in offspring of PM+ women (all differences were not significant) in the three gravidity groups. The results confirmed that placental IFN-gamma is related to LBW due to PM during first pregnancies and suggest that fetal ferritin plays a protective role. Because fetal cells are a source of placental IFN-gamma and cord ferritin, the fetal response to PM may modify the risk of LBW.