Elevated serum acylated (biologically active) ghrelin and resistin levels associate with pregnancy-induced weight gain and insulin resistance

Circulating inflammatory cytokines and gestational diabetes mellitus: Unraveling the role of macrophage migration inhibitory factor (MIF) through a bidirectional mendelian randomization study

BACKGROUND

Several studies have identified associations between some of circulating inflammatory cytokines and gestational diabetes mellitus (GDM). However, the causal role of these associations remains unclear and unsystematic. We aimed to provide evidence for the causal relationships between circulating inflammatory cytokines and gestational diabetes mellitus.

METHODS

We performed bidirectional two-sample Mendelian randomization (2SMR) to investigate the causal connection between circulating inflammatory cytokines and gestational diabetes mellitus. Publicly accessible data for circulating inflammatory cytokines (8,293 individuals) and gestational diabetes mellitus (123,579 individuals) were obtained from genome-wide association study (GWAS).

RESULTS

Only one causal association was identified between circulating inflammatory cytokines and GDM. The inverse variance weighting (IVW) method showed that macrophage migration inhibitory factor (MIF) increased the risk of GDM (OR 1.162, 95%CI 1.044,1.293). Moreover, two causal associations were detected between GDM and circulating inflammatory cytokines. GDM was negatively correlated with interferon gamma-induced protein 10 (IP10) (Beta -0.129, 95%CI -0.236,-0.231) and interleukin-18 (IL18) (Beta -0.133, 95%CI -0.241,-0.026).

CONCLUSION

Mendelian randomization study revealed MIF as a risk factor for gestational diabetes mellitus. This finding offers a new and valuable insight into the pathophysiological mechanisms underlying GDM.

Impact of Ghrelin on Islet Size in Nonpregnant and Pregnant Female Mice

Reducing ghrelin by ghrelin gene knockout (GKO), ghrelin-cell ablation, or high-fat diet feeding increases islet size and β-cell mass in male mice. Here we determined if reducing ghrelin also enlarges islets in females and if pregnancy-associated changes in islet size are related to reduced ghrelin. Islet size and β-cell mass were larger (P = .057 for β-cell mass) in female GKO mice. Pregnancy was associated with reduced ghrelin and increased liver-expressed antimicrobial peptide-2 (LEAP2; a ghrelin receptor antagonist) in wild-type mice. Ghrelin deletion and pregnancy each increased islet size (by ∼19.9-30.2% and ∼34.9-46.4%, respectively), percentage of large islets (>25 µm2×103, by ∼21.8-42% and ∼21.2-41.2%, respectively), and β-cell mass (by ∼15.7-23.8% and ∼65.2-76.8%, respectively). Neither islet cross-sectional area, β-cell cross-sectional area, nor β-cell mass correlated with plasma ghrelin, although all positively correlated with LEAP2 (P = .081 for islet cross-sectional area). In ad lib-fed mice, there was an effect of pregnancy, but not ghrelin deletion, to change (raise) plasma insulin without impacting blood glucose. Similarly, there was an effect of pregnancy, but not ghrelin deletion, to change (lower) blood glucose area under the curve during a glucose tolerance test. Thus, genetic deletion of ghrelin increases islet size and β-cell cross-sectional area in female mice, similar to males. Yet, despite pregnancy-associated reductions in ghrelin, other factors appear to govern islet enlargement and changes to insulin sensitivity and glucose tolerance in the setting of pregnancy. In the case of islet size and β-cell mass, one of those factors may be the pregnancy-associated increase in LEAP2.

Maternal adaptations to food intake across pregnancy: Central and peripheral mechanisms

A sufficient and balanced maternal diet is critical to meet the nutritional demands of the developing fetus and to facilitate deposition of fat reserves for lactation. Multiple adaptations occur to meet these energy requirements, including reductions in energy expenditure and increases in maternal food intake. The central nervous system plays a vital role in the regulation of food intake and energy homeostasis and responds to multiple metabolic and nutrient cues, including those arising from the gastrointestinal tract. This review describes the nutrient requirements of pregnancy and the impact of over- and undernutrition on the risk of pregnancy complications and adult disease in progeny. The central and peripheral regulation of food intake is then discussed, with particular emphasis on the adaptations that occur during pregnancy and the mechanisms that drive these changes, including the possible role of the pregnancy-associated hormones progesterone, estrogen, prolactin, and growth hormone. We identify the need for deeper mechanistic understanding of maternal adaptations, in particular, changes in gut-brain axis satiety signaling. Improved understanding of food intake regulation during pregnancy will provide a basis to inform strategies that prevent maternal under- or overnutrition, improve fetal health, and reduce the long-term health and economic burden for mothers and offspring.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus-pituitary-gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

Age, gestational and heat stress effects on ghrelin secretion in dairy cattle

It is known that heat stress decreases dry matter intake in cattle with impacts on milk production and fertility. Ghrelin is an orexigenic hormone with suppressive effects on reproduction. In this study, we investigated the effects of heat stress and gestational status on ghrelin secretion and its possible associations with DMI in Holstein cattle. The study was conducted in a dairy farm without any artificial cooling measures. The animals were fed a total mixed ration twice daily; each morning the leftovers were removed and weighted. Lactating cows and heifers were used during the winter and the summer; in each season 8 groups were formed as following: non-pregnant cows (n = 10) and non-pregnant heifers (n = 10) and pregnant cows (3 groups, each n = 8) and heifers (3 groups, each n = 10), being at the 1st (days 65-90), the 2nd (days 114-144) and the 3rd (dry cows, days 198-220; heifers, days 192-230) trimester of gestation. In each season the blood samples were collected from all groups on the same day, 1 h prior to morning feeding. In the winter, the Temperature Humidity Index (THI) was 58 in the winter and 73 in the summer. Normal and acidified sera were stored at -20 °C and analyzed for cortisol, total and acylated ghrelin concentrations, respectively. T-Test and Welch-Satterthwaite were performed for continuous data comparison, while two-way ANOVA to test for differences between gestation and season. Feed refusals were higher (p < 0.01) during the summer compared to the winter. In cows, total ghrelin levels differed between gestation stages in winter and summer(p < 0.04), while acylated ghrelin levels differed by gestation stage in winter (p < 0.001) but not in summer. There was an effect of season by the gestational stage in the pattern of acylated (p < 0.001) but not of total ghrelin. In heifers, the pattern of total and acylated ghrelin secretion was not affected by season or gestation stage (p > 0.05). Both in cows and heifers, acylated ghrelin levels were lower in summer compared to winter, (p < 0.002). During the summer months the low ghrelin levels might explain the reduced feed consumption of heat stressed animals. We infer that the lactation-induced altered metabolic status of the animals governed the different ghrelin levels at various gestational stages in cows and heifers.

Placental Regulation of Energy Homeostasis During Human Pregnancy

Successful pregnancies rely on sufficient energy and nutrient supply, which require the mother to metabolically adapt to support fetal needs. The placenta has a critical role in this process, as this specialized organ produces hormones and peptides that regulate fetal and maternal metabolism. The ability for the mother to metabolically adapt to support the fetus depends on maternal prepregnancy health. Two-thirds of pregnancies in the United States involve obese or overweight women at the time of conception. This poses significant risks for the infant and mother by disrupting metabolic changes that would normally occur during pregnancy. Despite well characterized functions of placental hormones, there is scarce knowledge surrounding placental endocrine regulation of maternal metabolic trends in pathological pregnancies. In this review, we discuss current efforts to close this gap of knowledge and highlight areas where more research is needed. As the intrauterine environment predetermines the health and wellbeing of the offspring in later life, adequate metabolic control is essential for a successful pregnancy outcome. Understanding how placental hormones contribute to aberrant metabolic adaptations in pathological pregnancies may unveil disease mechanisms and provide methods for better identification and treatment. Studies discussed in this review were identified through PubMed searches between the years of 1966 to the present. We investigated studies of normal pregnancy and metabolic disorders in pregnancy that focused on energy requirements during pregnancy, endocrine regulation of glucose metabolism and insulin resistance, cholesterol and lipid metabolism, and placental hormone regulation.

Impact of pregravid obesity on maternal and fetal immunity: Fertile grounds for reprogramming

Maternal pregravid obesity results in several adverse health outcomes during pregnancy, including increased risk of gestational diabetes, preeclampsia, placental abruption, and complications at delivery. Additionally, pregravid obesity and in utero exposure to high fat diet have been shown to have detrimental effects on fetal programming, predisposing the offspring to adverse cardiometabolic, endocrine, and neurodevelopmental outcomes. More recently, a deeper appreciation for the modulation of offspring immunity and infectious disease-related outcomes by maternal pregravid obesity has emerged. This review will describe currently available animal models for studying the impact of maternal pregravid obesity on fetal immunity and review the data from clinical and animal model studies. We also examine the burden of pregravid obesity on the maternal-fetal interface and the link between placental and systemic inflammation. Finally, we discuss future studies needed to identify key mechanistic underpinnings that link maternal inflammatory changes and fetal cellular reprogramming events.

The role of adipokines in the pathogenesis of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a complex condition whose physiopathology to date has not been completely clarified. Two major metabolic disorders, insulin resistance and β-cells dysfunction, play currently major role in pathogenesis of GDM. These elements are influenced by the amount of adipose tissue present before and/or during the pregnancy. Consequently, adipokines (adiponectin (APN), leptin (LPT), adipocyte fatty acid-binding protein, resistin, visfatin, omentin, vaspin, apelin, chemerin) secreted by adipose tissue, may contribute directly and/or indirectly, through the enhancement of chronic inflammation, aggravating insulin resistance and promoting GDM onset. This review aims to outline the potential physiopathological and prognostic role in GDM of adipokines, mainly APN and LPT.

Altered Resistin Concentrations in Mid-trimester Amniotic Fluid of Fetuses With Trisomies 18 and 13: A Window onto the Pathophysiology of Trisomies 18 and 13

BACKGROUND/AIM

The study aimed to examine whether resistin is present in second trimester amniotic fluid from pregnancies with trisomy 18 and 13 and evaluate its concentration in comparison with euploid pregnancies.

PATIENTS AND METHODS

The study included 37 women who underwent amniocentesis. Eleven fetuses had trisomy 18, 3 had trisomy 13, while 23 had a normal karyotype.

RESULTS

Resistin was detected in all cases. The mean level of resistin in trisomy 18 was statistically significantly lower compared to euploid controls. Resistin levels in all abnormal cases were below its median concentration in euploid controls. ROC analysis showed very good prognostic value for both trisomies.

CONCLUSION

Resistin is a constituent of mid-trimester amniotic fluid of pregnancies with trisomies 13 and 18, exhibiting lower levels than those in euploid fetuses. The reduced levels of resistin in amniotic fluid may be associated with early changes in metabolic pathways and immunoinflammatory responses.

Serum levels of adipokines in gestational diabetes: a systematic review

OBJECTIVE

To determine the difference of serum levels of 10 adipokines (apelin, chemerin, fatty acid-binding protein-4, fibroblast growth factor-21, monocyte chemoattractant protein-1, nesfatin-1, omentin-1, resistin, vaspin, and visfatin) among women with gestational diabetes and healthy pregnant controls.

MATERIALS AND METHODS

Literature search was conducted using the Medline (1966-2018), Scopus (2004-2018), Cochrane Central Register of Controlled Trials (CENTRAL) (1999-2018), Clinicaltrials.gov (2008-2018) and Google Scholar (2004-2018) databases, along with the reference list of the included studies.

RESULTS

Ninety-one studies were included in the present review, with a total number of 11,074 pregnant women. A meta-analysis was not conducted due to the high inter-study heterogeneity. Current evidence suggests that fatty acid-binding protein-4 levels are significantly increased in pregnancies complicated with gestational diabetes, while no association of serum apelin and monocyte chemoattractant protein-1 with the disease can be supported. Data regarding the rest adipokines are conflicting, since the available studies did not unanimously indicate a significant change of their levels in gestational diabetes.

CONCLUSIONS

The findings of the present systematic review suggest the promising role of fatty acid-binding protein-4 in the prediction of gestational diabetes, while inconsistent evidence exists regarding the rest novel adipokines. Future cohorts are needed to assess their predictive efficacy and fully elucidate their contribution in the disease.

Leptin and Ghrelin in Excessive Gestational Weight Gain-Association between Mothers and Offspring

Two-thirds of pregnant women exceed gestational weight gain recommendations. Excessive gestational weight gain (EGWG) appears to be associated with offspring's complications induced by mechanisms that are still unclear. The aim of this study was to investigate whether umbilical cord leptin (UCL) and ghrelin (UCG) concentrations are altered in full-term neonates born to EGWG mothers and whether neonatal anthropometric measurements correlate with UCL and UCG levels and maternal serum ghrelin and leptin as well as urine ghrelin concentrations. The study subjects were divided into two groups, 28 healthy controls and 38 patients with EGWG. Lower UCL and UCG levels were observed in neonates born to healthy mothers but only in male newborns. In the control group UCG concentrations correlated positively with neonatal birth weight, body length and head circumference. In the control group maternal serum ghrelin levels correlated negatively with neonatal birth weight, body length and head circumference as well as positively with chest circumference. In the EGWG group UCG concentrations correlated negatively with neonatal birth weight and birth body length. UCL correlated positively with birth body length in EGWG group and negatively with head circumference in the control group. In conclusion, EGWG is associated with disturbances in UCL and UCG concentrations.

Maternal resistin predisposes offspring to hypothalamic inflammation and body weight gain

Resistin promotes hypothalamic neuroinflammation and insulin resistance through Toll like receptor 4 (TLR4), this hormone is thought to be a link between obesity and insulin-resistance. Indeed, resistin plasma levels are higher in obese and insulin resistant subjects. However, the impact of maternal resistin on the predisposition of offspring to hypothalamic neuroinflammation is unknown. Here, female mice were treated with resistin during gestation/lactation periods, then hypothalamic neuroinflammation was investigated in male offspring at p28 and p90. At p28, resistin increased the expression of inflammation markers (IL6, TNFα and NFκB) and TLR4 in the hypothalamus and decreased both hypothalamic insulin and leptin receptors' expression. The hypothalamic up-regulation IL6, TNFα and TLR4 was sustained until p90 promoting most likely hypothalamic inflammation. Maternal resistin also increased IL6 and TNFα in the adipose tissue of offspring at p90 associated with a higher body weight gain. In contrast, liver and muscle were not affected. These findings reveal that the augmentation of maternal resistin during gestation and lactation promotes hypothalamic and adipose tissue inflammation of offspring as evidenced by sustained increase of inflammation markers from weaning to adulthood. Thus, maternal resistin programs offspring hypothalamic and adipose tissue inflammation predisposing then offspring to body weight gain.

Maternal serum level of resistin is associated with risk for gestational diabetes mellitus: A meta-analysis

BACKGROUND

Resistin is most likely involved in the pathogenesis of gestational diabetes mellitus (GDM), but the existing findings are inconsistent.

AIM

To review the literature investigating the associations of the risk of GDM with serum level of resistin.

METHODS

A systematic literature search was performed using MEDLINE, EMBASE, and Web of Science (all databases). This meta-analysis included eligible studies that: (1) investigated the relationship between the risk of GDM and serum resistin; (2) included GDM cases and controls without GDM; (3) diagnosed GDM according to the oral glucose-tolerance test; (4) were performed in humans; (5) were published as full text articles in English; and (6) provided data with median and quartile range, median and minimum and maximum values, or mean and standard deviation. The pooled standardized mean difference (SMD) and 95% confidence interval (CI) were calculated to estimate the association between the risk of GDM and serum resistin. To analyze the potential influences of need for insulin in GDM patients and gestational age at blood sampling, we performed a subgroup analysis. Meta-regression with restricted maximum likelihood estimation was performed to assess the potentially important covariate exerting substantial impact on between-study heterogeneity.

RESULTS

The meta-analysis for the association between serum resistin level and GDM risk included 18 studies (22 comparisons) with 1041 cases and 1292 controls. The total results showed that the risk of GDM was associated with higher serum resistin level (SMD = 0.250, 95%CI: 0.116, 0.384). The “after 28 wk” subgroup, “no need for insulin” subgroup, and “need for insulin” subgroup indicated that higher serum resistin level was related to GDM risk (“after 28 wk” subgroup: SMD = 0.394, 95%CI: 0.108, 0.680; “no need for insulin” subgroup: SMD = 0.177, 95%CI: 0.018, 0.336; “need for insulin” subgroup: SMD = 0.403, 95%CI: 0.119, 0.687). The “before 14 wk” subgroup, “14-28 wk” subgroup, and “no information of need for insulin” subgroup showed a nonsignificant association between serum resistin level and GDM risk (“before 14 wk” subgroup: SMD = 0.087, 95%CI: -0.055, 0.230; “14-28 wk” subgroup: SMD = 0.217, 95%CI: -0.003, 0.436; “no information of need for insulin” subgroup: SMD = 0.356, 95%CI: -0.143, 0.855). The postpartum subgroup included only one study and showed that higher serum resistin level was related to GDM risk (SMD = 0.571, 95%CI: 0.054, 1.087) The meta-regression revealed that no need for insulin in GDM patients, age distribution similar between cases and controls, and ELISA all had a significant impact on between-study heterogeneity.

CONCLUSION

This meta-analysis supports that the maternal serum resistin level is associated with GDM risk.

Ghrelin in Serum and Urine of Post-Partum Women with Gestational Diabetes Mellitus

Women with a previous history of gestational diabetes mellitus (GDM) have a significantly increased risk of developing type 2 diabetes, obesity, and cardiovascular diseases in the future. The aim of the study was to evaluate ghrelin concentrations in serum and urine in the GDM group in the early post-partum period, with reference to laboratory results, body composition, and hydration status. The study subjects were divided into two groups, that is, 28 healthy controls and 26 patients with diagnosed GDM. The maternal body composition and hydration status were evaluated by the bioelectrical impedance analysis (BIA) method. The concentrations of ghrelin in the maternal serum and urine were determined via enzyme-linked immunosorbent assay (ELISA). The laboratory and BIA results of the mothers with GDM were different from those without GDM. Urine ghrelin positively correlated with serum ghrelin and high-density lipoprotein cholesterol (HDL) levels in healthy mothers. There were direct correlations between urine ghrelin and HDL as well as triglycerides levels in the GDM group. Neither the lean tissue index nor body cell mass index were related to the serum ghrelin concentrations in this group. Only the urine ghrelin of healthy mothers correlated with the fat tissue index. Our results draw attention to urine as an easily available and appropriable biological material for further studies.

Serum adipokines (adiponectin and resistin) correlation in developing gestational diabetes mellitus: pilot study

Adiponectin and resistin are adipose tissue-derived proteins with antagonistic actions; adiponectin has insulin sensitive properties while resistin is involved in the development of insulin resistance. We analyzed adiponectin and resistin levels in gestational diabetes mellitus (GDM) women to evaluate the association of these adipokines in a very high diabetes prevalence population. An age-matched case-control study of GDM and normal pregnant women in Saudi population. We recruited 90 pregnant women at 24-32 weeks of gestation. Glucose levels (fasting, 1, 2, and 3 h) and lipid parameters (cholesterol, triglyceride, HDL cholesterol, LDL cholesterol) were measured. Serum adiponectin and resistin levels were analyzed using Randox evidence biochip analyzer. Pearson's correlation coefficient was used to determine the association of adiponectin and resistin with GDM risk factors. GDM women showed significantly low adiponectin and high resistin levels when compared with control group. Pearson's correlation analysis of adiponectin and resistin in all the subjects with various GDM risk factors showed a negative association of adiponectin (r = -0.32, p = .05) and a positive correlation of resistin (r = 0.41, p = .01) with LDL cholesterol. This study analyzes adiponectin and resistin levels together, as accumulating evidences shows that these are involved in the pathophysiology of GDM. This is going to help to determine in conjunction with traditional risk factors the incremental value of circulating adiponectin and resistin in developing GDM.

The modulatory role of cytokines IL-4 and IL-17 in the functional activity of phagocytes in diabetic pregnant women

The study investigated the role of cytokines IL-4 and IL-17 in the modulation of the functional activity of mononuclear phagocytes in diabetic pregnant women with hyperglycemia. Sixty pregnant women were assigned to the following groups: nondiabetic (ND), mild gestational hyperglycemia (MGH), gestational diabetes mellitus (GDM), or type 2 diabetes mellitus (DM2). The functional activity of phagocytes from maternal blood, cord blood, and colostrum was assessed by determining their superoxide release, phagocytosis, microbicidal activity, and intracellular Ca²⁺ release. Irrespective of glycemic status, colostrum and blood cells treated with IL-4 and IL-17 increased superoxide release in the presence of enteropathogenic Escherichia coli (EPEC). The highest phagocytosis rate was observed in cells from the DM2 group treated with IL-4. In all the groups, phagocytes from colostrum, maternal blood, and cord blood exhibited higher microbicidal activity against EPEC when treated with cytokines. IL-17 increased intracellular Ca²⁺ release by colostrum phagocytes in diabetic groups. The results indicate that the IL-4 and IL-17 modulate the functional activity of phagocytes in the maternal blood, cord blood, and colostrum of diabetic mother. The natural immunity resulting from the interaction between the cells and cytokines tested may be an alternative procedure to improve the prognosis of maternal and newborn infections.

Linking Stress and Infertility: A Novel Role for Ghrelin

Infertility affects a remarkable one in four couples in developing countries. Psychological stress is a ubiquitous facet of life, and although stress affects us all at some point, prolonged or unmanageable stress may become harmful for some individuals, negatively impacting on their health, including fertility. For instance, women who struggle to conceive are twice as likely to suffer from emotional distress than fertile women. Assisted reproductive technology treatments place an additional physical, emotional, and financial burden of stress, particularly on women, who are often exposed to invasive techniques associated with treatment. Stress-reduction interventions can reduce negative affect and in some cases to improve in vitro fertilization outcomes. Although it has been well-established that stress negatively affects fertility in animal models, human research remains inconsistent due to individual differences and methodological flaws. Attempts to isolate single causal links between stress and infertility have not yet been successful due to their multifaceted etiologies. In this review, we will discuss the current literature in the field of stress-induced reproductive dysfunction based on animal and human models, and introduce a recently unexplored link between stress and infertility, the gut-derived hormone, ghrelin. We also present evidence from recent seminal studies demonstrating that ghrelin has a principal role in the stress response and reward processing, as well as in regulating reproductive function, and that these roles are tightly interlinked. Collectively, these data support the hypothesis that stress may negatively impact upon fertility at least in part by stimulating a dysregulation in ghrelin signaling.

Resistin role in development of gestational diabetes mellitus

Diabetes is estimated to be one of the major causes of deaths in most countries due to its high prevalence rate, which was 8.8% in 2015. Hyperglycemia detected during pregnancy is known as gestational diabetes mellitus and it increases the potential risk of development of Type 2 diabetes in mothers with its varying prevalence rate of 1-14% in different populations. It also leads to the higher risk of developing abnormal glucose tolerance and obesity in their child at an early age. Recent studies show that potential mediators of insulin resistance such as adipokines - adiponectin, leptin and resistin are important for glucose and lipid metabolism. Adipokines are directly involved in the regulation of insulin secretion and insulin sensitivity in the liver, muscle and adipose tissue. It is also involved in inflammation, adipose tissue accumulation, adverse fat distribution and subsequently affects glucose metabolism. This review highlights the role of resistin (an adipokine) in the development of gestational diabetes mellitus.

Maternal obesity and inflammatory mediators: A controversial association

The link between maternal obesity and inflammatory mediators is still unclear. Our aim was to summarize the main findings of recently published studies on this topic. We performed a search in Medline for studies published in the last years on obesity, human pregnancy, and inflammatory mediators. We report the findings of 30 studies. The characteristics and number of participants, study design, gestational age at sample collection, and type of sample varied widely. Approximately two-thirds of them investigated more than one mediator, and 50% included participants in only one trimester of pregnancy. The most frequently investigated mediators were leptin, tumour necrosis factor-alpha (TNF-α), and interleukin (IL)-6. Almost all studies reported an association between maternal obesity, leptin, and C-reactive protein (CRP) serum levels but not with IL-1β and IL-10. The association of IL-6, TNF-α, monocyte chemo-attractant protein-1 (MCP-1), adiponectin, and resistin with maternal obesity is still controversial. To clarify the physiopathological link between maternal obesity and inflammation, more high-quality studies are needed.

Early Pregnancy Biochemical Predictors of Gestational Diabetes Mellitus

PURPOSE OF REVIEW

Universal oral glucose tolerance-based screening is employed to identify pregnant women with gestational diabetes mellitus (GDM), as treatment of this condition decreases the risk of associated complications. A simple and accurate blood test which identifies women at low or high risk for GDM in the first trimester would have the potential to decrease costs and improve outcomes through prevention or treatment. This review summarizes published data on early pregnancy biomarkers which have been tested as predictors of GDM.

RECENT FINDINGS

A large number of first-trimester biochemical predictors of GDM have been reported, mostly in small case-control studies. These include glycemic markers (fasting glucose, post-load glucose, hemoglobin A1C), inflammatory markers (C-reactive protein, tumor necrosis factor-alpha), insulin resistance markers (fasting insulin, sex hormone-binding globulin), adipocyte-derived markers (adiponectin, leptin), placenta-derived markers (follistatin-like-3, placental growth factor, placental exosomes), and others (e.g., glycosylated fibronectin, soluble (pro)renin receptor, alanine aminotransferase, ferritin). A few large studies suggest that first-trimester fasting glucose or hemoglobin A1C may be useful for identifying women who would benefit from early GDM treatment. To translate the findings from observational studies of first-trimester biomarkers for GDM to clinical practice, trials or cost-effectiveness analyses of screening and treatment strategies based on these novel biomarkers are needed.

Altered cytokine network in gestational diabetes mellitus affects maternal insulin and placental-fetal development

Pregnancy is characterized by an altered inflammatory profile, compared to the non-pregnant state with an adequate balance between pro-and anti-inflammatory cytokines needed for normal development. Cytokines are small secreted proteins expressed mainly in immunocompetent cells in the reproductive system. From early developmental stages onward, the secretory activity of placenta cells clearly contributes to increase local as well as systemic levels of cytokines. The placental production of cytokines may affect mother and fetus independently. In turn because of this unique position at the maternal fetal interface, the placenta is also exposed to the regulatory influence of cytokines from maternal and fetal circulations, and hence, may be affected by changes in any of these. Gestational diabetes mellitus (GDM) is associated with an overall alteration of the cytokine network. This review discusses the changes that occur in cytokines post GDM and their negative effects on maternal insulin and placental-fetal development.

The potential role of biomarkers in predicting gestational diabetes

Gestational diabetes (GD) is a frequent complication during pregnancy and is associated with maternal and neonatal complications. It is suggested that a disturbing environment for the foetus, such as impaired glucose metabolism during intrauterine life, may result in enduring epigenetic changes leading to increased disease risk in adult life. Hence, early prediction of GD is vital. Current risk prediction models are based on maternal and clinical parameters, lacking a strong predictive value. Adipokines are mainly produced by adipocytes and suggested to be a link between obesity and its cardiovascular complications. Various adipokines, including adiponectin, leptin and TNF&, have shown to be dysregulated in GD. This review aims to outline biomarkers potentially associated with the pathophysiology of GD and discuss the role of integrating predictive biomarkers in current clinical risk prediction models, in order to enhance the identification of those at risk.

Active ghrelin and the postpartum

Postpartum depression (PPD) occurs in 10-15 % of women. The appetite hormone ghrelin, which fluctuates during pregnancy, is associated with depression in nonpregnant samples. Here, we examine the association between PPD and active ghrelin from pregnancy to postpartum. We additionally examine whether ghrelin changes from pregnancy to postpartum and differs between breastfeeding and non-breastfeeding women. Sixty women who participated in a survey examining PPD and had information in regard to ghrelin concentrations were included in the study. The Edinburgh Postnatal Depression Scale was used to assess symptoms of PPD. Raw ghrelin levels and ghrelin levels adjusted for creatinine were included as outcomes. Women screening positive for PPD at 12 weeks postpartum had higher pregnancy ghrelin concentrations. Ghrelin concentrations significantly decreased from pregnancy to 6 weeks postpartum and this change differed based on pregnancy depression status. Finally, ghrelin levels were lower in women who breastfed compared with women who were bottle-feeding. No significant findings remained once ghrelin levels were adjusted for creatinine. Although results do not suggest an association between PPD and ghrelin after adjusting for creatinine, future research should continue to explore this possibility extending further across the postpartum period with larger sample sizes.

First trimester screening for gestational diabetes mellitus by maternal factors and markers of inflammation

OBJECTIVE

To examine the potential role of maternal serum levels of tumor necrosis factor-α (TNF-α) and high sensitivity C-reactive protein (Hs-CRP) in the first trimester of pregnancy in the prediction of gestational diabetes mellitus (GDM).

METHODS

Maternal serum TNF-α and Hs-CRP concentrations were measured in a case-control study of singleton pregnancies at 11-13 weeks' gestation, which included 200 cases that subsequently developed GDM and 800 unaffected controls. Measured levels of TNF-α and Hs-CRP were expressed as multiples of the median (MoM) after adjustment for maternal characteristics and history. The performance of screening for GDM by maternal factors and MoM values of TNF-α and Hs-CRP was evaluated by the area under the receiver operating characteristic curves (AUROC).

RESULTS

In the GDM group, compared to the normal group, the median TNF-α was significantly increased (1.303 MoM, interquartile range [IQR] 1.151-1.475 vs. 1.0 MoM, IQR 0.940-1.064; p=0.031) and the median Hs-CRP was not significantly different (1.113 MoM, IQR 0.990-1.250 vs. 1.0 MoM, IQR 0.943-1.060; p=0.084). In the prediction of GDM, the AUROC for maternal characteristics with TNF-α or Hs-CRP was not significantly different than the AUROC for maternal characteristics alone (p=0.5055 and p=0.2197, respectively).

CONCLUSIONS

In pregnancies that develop GDM there is no evidence of an inflammatory response at 11-13 weeks' gestation and the levels of serum TNF-α and Hs-CRP are not useful in first-trimester screening for GDM.

Maternal Serum Resistin Is Reduced in First Trimester Preeclampsia Pregnancies and Is a Marker of Clinical Severity

OBJECTIVE

To examine whether resistin levels in first trimester maternal serum are associated with insulin resistance or preeclampsia (PE).

METHODS

A case-control study of maternal serum resistin concentration conducted using 285 normal pregnancies and 123 PE pregnancies matched for gestational age, parity and maternal age. Samples were taken in gestational weeks 10⁺⁰-13⁺⁶.

RESULTS

There was a negative correlation between resistin and clinical severity of PE, but no correlation with IS, TNF-α, body mass index, birth weight and pregnancy length.

CONCLUSIONS

Resistin is reduced in first trimester of PE pregnancies, particularly in severe PE. Inflammation and IS cannot explain this phenomenon.

The Role of Maternal Dietary Proteins in Development of Metabolic Syndrome in Offspring

The prevalence of metabolic syndrome and obesity has been increasing. Pre-natal environment has been suggested as a factor influencing the risk of metabolic syndrome in adulthood. Both observational and experimental studies showed that maternal diet is a major modifier of the development of regulatory systems in the offspring in utero and post-natally. Both protein content and source in maternal diet influence pre- and early post-natal development. High and low protein dams’ diets have detrimental effect on body weight, blood pressure191 and metabolic and intake regulatory systems in the offspring. Moreover, the role of the source of protein in a nutritionally adequate maternal diet in programming of food intake regulatory system, body weight, glucose metabolism and blood pressure in offspring is studied. However, underlying mechanisms are still elusive. The purpose of this review is to examine the current literature related to the role of proteins in maternal diets in development of characteristics of the metabolic syndrome in offspring.

The endocrine function of human placenta: an overview

During pregnancy, several tightly coordinated and regulated processes take place to enable proper fetal development and gestational success. The formation and development of the placenta is one of these critical pregnancy events. This organ plays essential roles during gestation, including fetal nourishment, support and protection, gas exchange and production of several hormones and other mediators. Placental hormones are mainly secreted by the syncytiotrophoblast, in a highly and tightly regulated way. These hormones are important for pregnancy establishment and maintenance, exerting autocrine and paracrine effects that regulate decidualization, placental development, angiogenesis, endometrial receptivity, embryo implantation, immunotolerance and fetal development. In addition, because they are released into maternal circulation, the profile of their blood levels throughout pregnancy has been the target of intense research towards finding potential robust and reliable biomarkers to predict and diagnose pregnancy-associated complications. In fact, altered levels of these hormones have been associated with some pathologies, such as chromosomal anomalies or pre-eclampsia. This review proposes to revise and update the main pregnancy-related hormones, addressing their major characteristics, molecular targets, function throughout pregnancy, regulators of their expression and their potential clinical interest.

Ghrelin-ghrelin O-acyltransferase system in the pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is currently considered as the most common liver disease in Western countries, and is rapidly becoming a serious threat to public health worldwide. However, the underlying mechanisms leading to the development of NAFLD are still not fully understood. The ghrelin-ghrelin O-acyltransferase (GOAT) system has recently been found to play a crucial role in both the development of steatosis and its progression to nonalcoholic steatohepatitis. Ghrelin, the natural ligand of the growth hormone secretagogue receptor, is a 28-amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by GOAT. The ghrelin-GOAT system is involved in insulin resistance, lipid metabolism dysfunction, and inflammation, all of which play important roles in the pathogenesis of NAFLD. A better understanding of ghrelin-GOAT system biology led to the identification of its potential roles in NAFLD. Molecular targets modulating ghrelin-GOAT levels and the biologic effects are being studied, which provide a new insight into the pathogenesis of NAFLD. This review probes into the possible relationship between the ghrelin-GOAT system and NAFLD, and considers the potential mechanisms by which the ghrelin-GOAT system brings about insulin resistance and other aspects concerning NAFLD.

Effects of the use of assisted reproductive technologies and an obesogenic environment on resistance artery function and diabetes biomarkers in mice offspring

Maternal obesity affects the incidence of cardiovascular disease and diabetes in offspring. Also the use of assisted reproductive technologies (ART) has been associated with cardiovascular deficiencies in offspring. Obese women often suffer from infertility and use ART to achieve a pregnancy, but the combined effects of maternal obesity and ART on cardiovascular health and incidence of diabetes in the offspring is not known. Here, we report the effects of the use of ART within an obesogenic environment, consisting of feeding a western diet (WD) to dams and offspring, on resistance artery function and presence of diabetes biomarkers in juvenile mice offspring. Our results indicate that WD and ART interacted to induce endothelial dysfunction in mesenteric resistance arteries isolated from 7-week-old mice offspring. This was determined by presence of a reduced acetylcholine-induced dilation compared to controls. The arteries from these WD-ART mice also had greater wall cross-sectional areas and wall to lumen ratios indicative of vascular hypertrophic remodeling. Of the diabetes biomarkers measured, only resistin was affected by a WD×ART interaction. Serum resistin was significantly greater in WD-ART offspring compared to controls. Diet and sex effects were observed in other diabetes biomarkers. Our conclusion is that in mice the use of ART within an obesogenic environment interacts to favor the development of endothelial dysfunction in the resistance arteries of juvenile offspring, while having marginal effects on diabetes biomarkers.

A gene variant in the transcription factor 7-like 2 (TCF7L2) is associated with an increased risk of gestational diabetes mellitus

OBJECTIVE

Adipokines play an important role in the pathogenesis of insulin resistance during pregnancy. We studied the association of genetic variants linked with type 2 diabetes in gestational diabetes mellitus (GDM) subjects and its influence on maternal adipokines.

STUDY DESIGN

We recruited 25 healthy pregnant women (Controls) and 45 women with GDM at 24-28 weeks of gestation. Maternal blood samples were collected at recruitment and delivery. Adipokines were determined at both sampling times. Genomic DNA was extracted from recruitment samples and FTO rs9939609, TCF7L2 rs4506565, rs7901695, rs12243326, rs12255372 and rs7903146, INSIG2 rs7566605, SREBF1 rs114001633, rs45535737 and rs12941356 and FATP4 rs2003560 genotyped.

RESULTS

Serum adiponectin was significantly lower in GDM than Controls at recruitment and showed a similar trend at delivery (p=0.060). In contrast, resistin tended to higher levels in GDM only at recruitment. TCF7L2 rs4506565 (OR=2.31, 95% CI: 1.97-5.01; p=0.031) and FTO rs9939609 (OR=2.17, 95% CI: 1.07-4.41; p=0.039) were associated with GDM risk. Women carrying the T allele of TCF7L2 rs4506565 had increases in plasma resistin of 9.38 μg/L (95% CI 1.39-17.37; p=0.022) per allele; this association remained significant after adjusting for pre-gestational body weight.

CONCLUSION

TCF7L2 rs4506565 variant (T/T) is associated with increased risk of GDM and plasma resistin concentrations in women with GDM.

Adipokines in gestational diabetes

Gestational diabetes is characterised by glucose intolerance with onset or first recognition during pregnancy. The disease shows facets of the metabolic syndrome including obesity, insulin resistance, and dyslipidaemia. Adipokines are a group of proteins secreted from adipocytes, which are dysregulated in obesity and contribute to metabolic and vascular complications. Recent studies have assessed the role of various adipokines including leptin, adiponectin, tumour necrosis factor α (TNFα), adipocyte fatty acid-binding protein (AFABP), retinol-binding protein 4 (RBP4), resistin, NAMPT, SERPINA12, chemerin, progranulin, FGF-21, TIMP1, LCN2, AZGP1, apelin (APLN), and omentin in gestational diabetes. This Review provides an overview of these key adipokines, their regulation in, and potential contribution to gestational diabetes. Based on the evidence so far, the adipokines adiponectin, leptin, TNFα, and AFABP seem to be the most probable candidates involved in the pathophysiology of gestational diabetes.

Role of ghrelin in fertilization, early embryo development, and implantation periods

In order to clarify the physiological role of ghrelin in gestation, we evaluated the effects of administration of exogenous ghrelin (2 or 4 nmol/animal per day) or its antagonist (6 nmol/animal per day of (d-Lys3)GHRP6) on fertilization, early embryo development, and implantation periods in mice. Three experiments were performed, treating female mice with ghrelin or its antagonist: i) starting from 1 week before copulation to 12 h after copulation, mice were killed at day 18 of gestation; ii) since ovulation induction until 80 h later, when we retrieved the embryos from oviducts/uterus, and iii) starting from days 3 to 7 of gestation (peri-implantation), mice were killed at day 18. In experiments 1 and 3, the antagonist and/or the highest dose of ghrelin significantly increased the percentage of atrophied fetuses and that of females exhibiting this finding or a higher amount of corpora lutea compared with fetuses (nCL/nF) (experiment 3: higher nCL/nF-atrophied fetuses: ghrelin 4, 71.4-71.4% and antagonist, 75.0-62.5% vs ghrelin 2, 46.2-15.4% and control, 10-0.0%; n=7-13 females/group; P<0.01). In experiment 2, the antagonist diminished the fertilization rate, and both, ghrelin and the antagonist, delayed embryo development (blastocysts: ghrelin 2, 62.5%; ghrelin 4, 50.6%; and antagonist, 61.0% vs control 78.4%; n=82-102 embryos/treatment; P<0.0001). In experiment 3, additionally, ghrelin (4 nmol/day) and the antagonist significantly diminished the weight gain of fetuses and dams during pregnancy. Our results indicate that not only hyperghrelinemia but also the inhibition of the endogenous ghrelin effects exerts negative effects on the fertilization, implantation, and embryo/fetal development periods, supporting the hypothesis that ghrelin (in 'adequate' concentrations) has a physiological role in early gestational events.

Structure and physiological actions of ghrelin

Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin.

Resistin concentration and gestational diabetes: a systematic review of the literature

Gestational diabetes (GD) exposes mothers and infants to the risk of immediate and later adverse outcomes. Increased insulin resistance is a common feature of GD and obesity. Because of its critical role in regulating insulin sensitivity, resistin has been implicated in the physiopathology of GD. The aim of this study was to review the existing literature on the relationship between circulating maternal resistin levels and GD. Three electronic databases (MEDLINE, EMBASE, and LILACS) were searched for pertinent studies published from 2001 to 2012, without language restrictions. Eleven studies, with a total of 639 participants between 23 and 41 weeks of gestation, were included. The number of GD patients per study ranged from 11 to 81, with varying degrees of disease severity and several different GD diagnostic criteria. Mean concentrations of resistin varied widely both in control women (0.05-22.21 ng/ml) and in GD patients (0.05-62.38 ng/ml). We performed a meta-analysis including a total of 10 studies, and also subgroup analyses according to gestational age at sample collection (up to 32 and >33 weeks). The pooled absolute mean difference (WMD) in resistin levels was slightly lower in GD patients than in controls, but this did not reach statistical significance (WMD=-0.02, 95% CI -0.07 to 0.04). According to the data from the 11 studies analyzed, there was no association between circulating resistin levels and GD. However, this result should be interpreted with caution owing to the large heterogeneity amongst the existing published studies.

Potential mechanisms of exercise in gestational diabetes

Gestational diabetes mellitus (GDM) is defined as glucose intolerance first diagnosed during pregnancy. This condition shares same array of underlying abnormalities as occurs in diabetes outside of pregnancy, for example, genetic and environmental causes. However, the role of a sedentary lifestyle and/or excess energy intake is more prominent in GDM. Physically active women are less likely to develop GDM and other pregnancy-related diseases. Weight gain in pregnancy causes increased release of adipokines from adipose tissue; many adipokines increase oxidative stress and insulin resistance. Increased intramyocellular lipids also increase cellular oxidative stress with subsequent generation of reactive oxygen species. A well-planned program of exercise is an important component of a healthy lifestyle and, in spite of old myths, is also recommended during pregnancy. This paper briefly reviews the role of adipokines in gestational diabetes and attempts to shed some light on the mechanisms by which exercise can be beneficial as an adjuvant therapy in GDM. In this regard, we discuss the mechanisms by which exercise increases insulin sensitivity, changes adipokine profile levels, and boosts antioxidant mechanisms.

Cytokine levels in gestational diabetes mellitus: a systematic review of the literature

PROBLEM

Gestational diabetes mellitus (GDM) is an inflammatory condition that involves unbalanced cytokine production. We carried out a systematic review on the relationship between GDM and maternal circulating levels of cytokines in the 2nd/3rd trimesters.

METHOD OF STUDY

Three electronic databases (MEDLINE, EMBASE and LILACS), were searched. Duplicate study selection, extraction and quality assessment was performed.

RESULTS

Twenty-two studies with 1982 participants reporting levels of 9 cytokines (IL-1B, IL-2, IL-6, IL-10, IL-13, IL-18, IFN-G, TGF-B and TNF-A) were included. Most studies differed considerably in selection criteria, sampling and assay methods and in reporting their results. Consequently, only two studies could be pooled: TNF-A concentration was slightly higher in GDM than in control patients, although not significant (WMD=0.45, 95% CI -0.34-1.23).

CONCLUSIONS

New studies with well-defined, more homogeneous methodological parameters are needed to detect whether there are significant differences in circulating levels of cytokines in patients with GDM.

Ghrelin, acylated ghrelin, leptin and PYY-3 levels in hyperemesis gravidarum

OBJECTIVE

To assess the serum levels of gut and adipocyte-derived metabolic hormones that control appetite, adipocity, weight gain and energy hemostasis, namely total ghrelin (TG), acylated ghrelin (AG), leptin and PYY-3 in hyperemesis gravidarum (HG).

METHODS

Plasma samples of 86 women in their first trimester pregnancies with HG (n = 30), morning sickness of pregnancy (MSP) (n = 34) and control (n = 22) groups were obtained. Serum levels of TG, AG, leptin and PYY-3 were compared between the groups, and the correlations with severity of symptoms using modified PUQE (Pregnancy Unique Quantification of Emesis) scoring, BMI, E2, hCG and TSH were calculated.

RESULTS

Levels of TG, AG, PYY-3 and the TG/leptin ratio were significantly higher in HG group compared to MSP and the control groups (p ≤ 0.017). AG/TG ratio was significantly lower in the HG group compared to both MSP and control groups (p ≤ 0.017). There were either weak or no significant statistical correlations between the gut and adipose-related hormones and the modified PUQE scores, BMI, E2, hCG and TSH.

CONCLUSION

Gut-derived metabolic hormones ghrelin, AG and PYY-3 may be involved in the HG pathophysiology.

Serum ghrelin level and TNF-α/ghrelin ratio in patients with previous myocardial infarction

BACKGROUND AND AIMS

Studies investigating serum ghrelin level in atherosclerosis yielded contradictory results. Interaction of ghrelin with adipocytokines is obscure in cardiovascular diseases. We undertook this study to determine which molecules influence ghrelin level and to see whether post-myocardial infarction (MI) patients have decreased ghrelin levels.

METHODS

In this cross-sectional study, acyl-ghrelin concentration was determined by radioimmunoassay in sera of 171 patients (ages 62 ± 6 years, mean ± SD) with previous MI and 81 age-matched referent subjects. We evaluated the associations of ghrelin with insulin, adiponectin, leptin, resistin, fetuin-A and tumor necrosis factor-alpha (TNF-α).

RESULTS

Patients had lower ghrelin levels compared to referent subjects (240.55 ± 59.33 vs. 337.96 ± 30.75 pg/mL, p <0.001) even after excluding diabetic and obese patients (240.63 ± 54.08 vs. 337.96 ± 30.75, p <0.001). In multivariate analysis, insulin (β = -0.327, p <0.001) and adiponectin (β = 0.301, p <0.001) determined ghrelin level (R(2) = 0.199, p <0.001). There was no association between ghrelin and TNF-α levels. In discriminant analysis using ghrelin, adiponectin, leptin, fetuin-A, resistin and TNF-α, the structure matrix revealed ghrelin and TNF-α as strongest predictors for belonging to the patient group (0.760 and -0.569, respectively). Using these two parameters, 89.7% of cases were correctly classified. Subjects with high TNF-α/ghrelin ratio had 11.25 times higher chance for belonging to the patient group (95% CI 5.80-21.80; χ(2) (1) = 215.6, p <0.001)

CONCLUSIONS

Acylated ghrelin levels are decreased in patients with coronary atherosclerosis, independently of body weight and the presence of type 2 diabetes mellitus. Ghrelin level is determined by elevated insulin and decreased adiponectin levels. Ghrelin alone or in combination with TNF-α may prove to be a novel indicator of coronary atherosclerosis.

Maternal serum resistin at 11 to 13 weeks' gestation in normal and pathological pregnancies

The objective was to examine maternal serum levels of resistin at 11 to 13 weeks' gestation in normal and pathological pregnancies. Serum resistin, pregnancy-associated plasma protein A (PAPP-A), and uterine artery pulsatility index (PI) at 11 to 13 weeks were measured in 480 singleton pregnancies, including 240 with normal outcome, 60 that subsequently developed preeclampsia (PE), 60 that developed gestational diabetes mellitus (GDM), 60 that delivered large for gestational age (LGA) neonates, and 60 that delivered small for gestational age (SGA) neonates. Each value in both the normal and pathological outcome groups was expressed as a multiple of the expected normal median (MoM), and the median MoM values in the outcome groups were compared. In the PE group, compared with the controls, there were an increase in median resistin (1.22 MoM, P = .003) and uterine artery PI (1.25 MoM, P < .0001) and a decrease in serum PAPP-A (0.72, P < .0001). There was no significant association between serum resistin with either uterine artery PI (P = .415) or serum PAPP-A (P = .290). In the SGA, LGA, and GDM groups, serum resistin MoM was not significantly different from that of the controls (P = .415, P = .702, and P = .549, respectively). In pregnancies that develop PE, maternal serum resistin concentration at 11 to 13 weeks is increased in a manner not related to altered placental perfusion or function. In pregnancies complicated by the development of GDM or delivery of SGA or LGA neonates, serum resistin is not significantly altered.

Role of adipokines and other inflammatory mediators in gestational diabetes mellitus and previous gestational diabetes mellitus

Previous Gestational Diabetes Mellitus (pGDM) is a common condition and has been associated with future development of Type 2 Diabetes Mellitus (T2DM) and Metabolic Syndrome (MS) in women affected. The pathogenesis and risk factors implicated in the development of these conditions later in the lives of women with pGDM are not as yet fully understood. Research has recently focused on a group of substances produced mainly by adipose tissue called adipokines, this group including, among others, adiponectin, leptin, Retinol-Binding Protein-4 (RBP-4), and resistin. These substances as well as other inflammatory mediators (CRP, IL-6, PAI-1, TNF-α) seem to play an important role in glucose tolerance and insulin sensitivity dysregulation in women with pGDM. We summarize the data available on the role of these molecules.

Recent advances in potential clinical application of ghrelin in obesity

Ghrelin is the natural ligand of the growth hormone secretagogue receptor (GHS-R1a). Ghrelin is a 28 amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by ghrelin O-acyltransferase (GOAT). Ghrelin stimulates growth hormone secretion, but also appetite, food intake, weight gain, and gastric emptying. Ghrelin is involved in weight regulation, obesity, type 2 diabetes, and metabolic syndrome. Furthermore, a better understanding of ghrelin biology led to the identification of molecular targets modulating ghrelin levels and/or its biological effects: GOAT, ghrelin, and GHS-R1a. Furthermore, a recent discovery, showing the involvement of bitter taste receptor T2R in ghrelin secretion and/or synthesis and food intake, suggested that T2R could represent an additional interesting molecular target. Several classes of ghrelin-related pharmacological tools for the treatment of obesity have been or could be developed to modulate the identified molecular targets.

Ablations of ghrelin and ghrelin receptor exhibit differential metabolic phenotypes and thermogenic capacity during aging

Background

Obesity is a hallmark of aging in many Western societies, and is a precursor to numerous serious age-related diseases. Ghrelin (Ghrl), via its receptor (growth hormone secretagogue receptor, GHS-R), is shown to stimulate GH secretion and appetite. Surprisingly, our previous studies showed that Ghrl^-/- mice have impaired thermoregulatory responses to cold and fasting stresses, while Ghsr^-/- mice are adaptive.

Methodology/Principal Findings

To elucidate the mechanism, we analyzed the complete metabolic profiles of younger (3–4 months) and older (10–12 months) Ghrl^-/- and Ghsr^-/- mice. Food intake and locomotor activity were comparable for both null mice and their wild-type (WT) counterparts, regardless of age. There was also no difference in body composition between younger null mice and their WT counterparts. As the WT mice aged, as expected, the fat/lean ratio increased and energy expenditure (EE) decreased. Remarkably, however, older Ghsr^-/- mice exhibited reduced fat/lean ratio and increased EE when compared to older WT mice, thus retaining a youthful lean and high EE phenotype; in comparison, there was no significant difference with EE in Ghrl^-/- mice. In line with the EE data, the thermogenic regulator, uncoupling protein 1 (UCP1), was significantly up-regulated in brown adipose tissue (BAT) of Ghsr^-/- mice, but not in Ghrl^-/- mice.

Conclusions

Our data therefore suggest that GHS-R ablation activates adaptive thermogenic function(s) in BAT and increases EE, thereby enabling the retention of a lean phenotype. This is the first direct evidence that the ghrelin signaling pathway regulates fat-burning BAT to affect energy balance during aging. This regulation is likely mediated through an as-yet-unidentified new ligand of GHS-R.

Maternal serum resistin concentrations in gestational diabetes mellitus and normal pregnancies

AIM

To investigate changes in maternal serum resistin levels during pregnancy and postpartum and clarify their relationship to insulin resistance.

METHODS

Thirty normal pregnant women were compared to 30 women diagnosed with gestational diabetes mellitus (GDM). Serum resistin levels were collected at the time of glucose challenge test (26-28 weeks), at 38 gestational weeks and at the third postpartum day and measured with enzyme immunoassay. Correlation of resistin to the homeostatic model assessment-insulin resistance (HOMA-IR) was performed.

RESULTS

Maternal serum resistin levels at 38 weeks were significantly higher in pregnant women with GDM compared to the control group (0.28 vs 0.21 ng/mL, P = 0.02) and the same was true for the immediate puerperium (0.25 vs 0.19 ng/mL, P = 0.03). A significant increase in resistin levels was observed in GDM women from 26-28 weeks to 38 weeks (0.21 vs 0.28 ng/mL, P = 0.02), but not in controls. A decrease in serum resistin levels was noted in both the GDM and control groups, at 38 weeks and the immediate postpartum period, but this decrease did not reach statistical significance in either of the two groups. Resistin levels were positively correlated to HOMA-IR at 26-28 weeks of gestation (r = +0.253, P = 0.05).

CONCLUSION

GDM is associated with increased resistin serum levels in term pregnancy as well as postpartum. Resistin is positively correlated to HOMA-IR at 26-28 weeks of gestation. A reduction in maternal resistin after delivery indicates a significant placental or fetal contribution in the production of resistin.