Resistin is expressed in the human placenta

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Resistin and leptin in breast milk and infants in early life

BACKGROUND

The role of adipokines in early life is considered an emerging topic issue in nutritional researches.

AIMS

To evaluate serum resistin and leptin concentrations and their relations in infants and in breast milk.

STUDY DESIGN

We enrolled 41 term, AGA, healthy infants, of which 23 exclusively breast-fed (BF) and 18 formula-fed (FF), aged less than 6 months. Breast milk (BM) samples were collected from 23 breastfeeding mothers of the infants enrolled. Resistin concentration in serum and BM was determined by ELISA test (Human-Resistin-ELISA, Mediagnost, Reutlingen, Germany). Leptin concentration was determined by Radioimmunoassay method (LEP-R40, Mediagnost, Reutlingen, Germany). Infants weight, length and body mass index were measured. We used Mann-Whitney test. Spearman correlation was applied. Statistical significance was set at p<0.05. Data are reported as median and interquartile range (IR).

RESULTS

Infants serum resistin concentration was 9.30 (5.02) ng/ml. Breast milk resistin concentration (n=23) was 0.18 (0.44) ng/ml. Leptin concentration was 3.04 (3.68) ng/ml in infants serum and in BM was 2.34 (5.73) ng/ml. Serum resistin concentrations in BF infants correlated positively with BM resistin (r=0.636, p=0.035). We have shown a positive correlation between resistin and leptin in total group of infants (r=0.44, p=0.05), confirmed in breastfed subjects (r=0.65, p=0.02). No correlations were found between serum hormones and anthropometric parameters of infants.

CONCLUSION

Our findings show interestingly a positive correlation between resistin concentrations in BF infants serum and in BM and between resistin and leptin in infants.

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.

ITIH-5 expression in human adipose tissue is increased in obesity

Adipocytes secrete many proteins that regulate metabolic functions. The gene inter-α (globulin) inhibitor H5 (ITIH-5) encodes a secreted protein and is known to be expressed abundantly in the placenta. However, using gene expression profiles data we observed high expression of ITIH-5 in adipose tissue. The aim of this study was to test the hypothesis that ITIH-5 is strongly expressed in human adipocytes and adipose tissue, and is related to obesity and clinical metabolic variables. ITIH-5 adipose tissue mRNA expression was analyzed with DNA microarray and real-time PCR, and its association with clinical variables was examined. ITIH-5 protein expression was analyzed using western blot. ITIH-5 mRNA expression was abundant in human adipose tissue, adipocytes, and placenta, and higher in subcutaneous (sc) compared to omental adipose tissue (P < 0.0001). ITIH-5 mRNA and protein expression in sc adipose tissue were higher in obese compared to lean subjects (P < 0.0001 and P < 0.001, respectively). ITIH-5 mRNA expression was reduced after diet-induced weight loss (P < 0.0001). ITIH-5 mRNA expression was associated with anthropometry and clinical metabolic variables. In conclusion, ITIH-5 is highly expressed in sc adipose tissue, increased in obesity, down regulated after weight loss, and associated with measures of body size and metabolism. Together, this indicates that ITIH-5 merits further investigation as a regulator of human metabolism.

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.

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

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

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Adipokines: new emerging roles in fertility and reproduction

Adipose tissue is a specialized endocrine and paracrine organ producing specific factors called adipokines. It is well known that adipokines balance is fundamental to prevent obesity, metabolic syndrome, and cardiovascular diseases. During the last years, new roles of adipokines have been emerging in the field of fertility and reproduction. Although the literature is still quite controversial, this review serves to resume current knowledge on this topic. Alterations in adipokine levels or in their mechanism of action are associated with fertility impairment and pregnancy diseases, as well as with obesity, metabolic syndrome, and cardiovascular diseases. Normal levels of adipokines are fundamental to maintain integrity of hypothalamus-pituitary-gonadal axis, regular ovulatory processes, successful embryo implantation, and physiologic pregnancy. More efforts are needed to understand the mechanisms and to the extent to which adipokine changes are involved in the impairment of fertility and pregnancy outcome, to find possible medical treatments.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this educational activity, the obstetrician/gynecologist should be better able to demonstrate current knowledge in the research field of adipokines in fertility and reproduction; evaluate the central role of metabolism balance in good pregnancy outcome; and apply new perspectives of studies.

Breast milk hormones and regulation of glucose homeostasis

Growing evidence suggests that a complex relationship exists between the central nervous system and peripheral organs involved in energy homeostasis. It consists in the balance between food intake and energy expenditure and includes the regulation of nutrient levels in storage organs, as well as in blood, in particular blood glucose. Therefore, food intake, energy expenditure, and glucose homeostasis are strictly connected to each other. Several hormones, such as leptin, adiponectin, resistin, and ghrelin, are involved in this complex regulation. These hormones play a role in the regulation of glucose metabolism and are involved in the development of obesity, diabetes, and metabolic syndrome. Recently, their presence in breast milk has been detected, suggesting that they may be involved in the regulation of growth in early infancy and could influence the programming of energy balance later in life. This paper focuses on hormones present in breast milk and their role in glucose homeostasis.

Resistin concentration is increased in the peritoneal fluid of women with endometriosis

PROBLEM

The aim of this study was to investigate the concentration of resistin and adiponectin in the peritoneal fluid (PF) of patients with endometriosis.

METHOD OF STUDY

PF sampling was obtained from women with (n = 48) and without endometriosis (n = 36), and the anthropometric indices of the patients were measured. Resistin and adiponectin concentrations in the PF were determined using the enzyme-linked immunosorbent assay.

RESULTS

The mean concentration of PF resistin was significantly higher in women with endometriosis compared to the controls. PF resistin concentrations were not associated with any of the anthropometric indices. The PF adiponectin did not differ between the two groups, but showed a significant association with the weight, body mass index, and hip circumference. After adjusting for these factors, PF adiponectin expression was not associated with endometriosis.

CONCLUSION

The findings of this study suggest a potent role for resistin in endometriosis. Further studies are needed to elucidate the biological implications of resistin in endometriosis.

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.

Maternal and umbilical resistin levels do not correlate with infant birth weight either in normal pregnancies and or in pregnancies complicated with gestational diabetes

OBJECTIVE

To evaluate the role of resistin in the pathophysiology of insulin resistance during pregnancy and on the birth weight of infants born from women with gestational diabetes (GDM).

MATERIAL AND METHODS

Thirty women diagnosed with GDM were compared to 30 normal pregnant controls. Maternal serum resistin and insulin levels were measured at the time of the oral glucose tolerance test screening. In addition, umbilical levels of resistin and insulin were measured at the time of delivery.

RESULTS

There was no difference in maternal serum resistin levels in women with GDM as compared to normal controls at 24-26 weeks. There was no difference in umbilical resistin levels between the infants born in the two groups. There was no correlation between infant weight and either maternal resistin at 24-26 week or umbilical resistin levels.

CONCLUSION

There were no significant differences in umbilical resistin levels between infants born of women with GDM as compared to normal pregnant women. In addition, there was no correlation between resistin levels during pregnancy, as well as between umbilical resistin levels and neonatal birth weight. In conclusion, resistin seems to play a rather minor role in the pathophysiology of GDM and the energy metabolism during fetal life.

The role of adipocytokines in fetal growth

Cumulative evidence suggests that the origins of obesity may occur during fetal development. In this respect, the concept of "developmental programming" was introduced and supported by experimental and epidemiological data. This concept supports the idea that the nutritional and hormonal status during pregnancy could irreversibly interfere in metabolism control. The mechanisms responsible for this developmental programming remain poorly documented. However, recent research indicates that adipocytokines may play a critical role in this process. Thus, leptin, adiponectin, and the recently identified resistin, visfatin, and apelin, all exert effects on fat, muscle, and liver cells early in life. The aforementioned adipocytokines are secreted by adipocytes and human placenta during fetal life and may play a major role in the etiopathogenesis of the metabolic syndrome. This review will focus on the intrauterine expression of adipocytokines, their contribution to the hormonal control of fetal growth, and their role in restricted and exaggerated intrauterine growth.

Cord blood resistin and adiponectin in term newborns of diabetic mothers

INTRODUCTION

Adipose tissue can release hormones into the blood stream in response to specific extracellular stimuli or changes in metabolic status. Resistin, an adipose-secreted factor, is primarily involved in the modulation of insulin sensitivity and adipocyte differentiation. Adiponectin, an adipocyte-specific hormone with insulin sensitizing, anti-inflammatory and anti-atherogenic effects, is reduced in obesity and type II diabetes. The aim of the study was to assess the influence of maternal pre-existing diabetes on cord blood resistin and adiponectin at birth in relation to neonatal anthropometric parameters and cord blood insulin levels.

MATERIAL AND METHODS

A total of 60 term newborns were prospectively enrolled and categorized into three groups: 20 were macrosomic infants of pre-gestational diabetic mothers (group I), 20 were non-macrosomic infants of pre-gestational diabetic mothers (group II) and 20 were healthy non-macrosomic infants born to non-diabetic mothers serving as controls (group III). Infants' anthropometric indices were recorded. Cord blood samples for glucose, insulin, resistin and adiponectin assay, together with maternal glycosylated haemoglobin were obtained.

RESULTS

Serum insulin was increased while resistin and adiponectin were significantly decreased in infants of diabetic mothers (IDMs) compared to the control group. Serum glucose, insulin, resistin and adiponectin were comparable in group I and II. Cord serum resistin correlated positively with cord blood glucose in IDMs in both macrosomic and non-macrosomic groups. Cord serum insulin correlated positively with triceps skinfold thickness in all studied neonates. Cord serum resistin and adiponectin showed no correlation with neonatal anthropometric indices. Multiple regression analysis demonstrated that insulin, resistin and adiponectin together were highly correlated with birth weight, with adiponectin as the one responsible for this positive correlation.

CONCLUSIONS

Infants of diabetic mothers had elevated levels of cord serum insulin and suppressed levels of cord serum resistin and adiponectin, suggesting that the regulation of these metabolic pathways is probably operational before birth. Levels were comparable in both macrosomic and non-macrosomic neonates.

Hyperresistinemia - a novel feature in systemic infection during human pregnancy

PROBLEM

Resistin, originally described as an adipokine, has emerged as a potent pro-inflammatory protein associated with both acute and chronic inflammation. Moreover, resistin has been proposed as a powerful marker of sepsis severity, as well as a predictor of survival of critically ill non-pregnant patients. The aim of this study was to determine whether pyelonephritis during pregnancy is associated with changes in maternal plasma resistin concentrations.

METHODS OF STUDY

This cross-sectional study included the following groups: (i) normal pregnant women (n = 85) and (ii) pregnant women with pyelonephritis (n = 40). Maternal plasma resistin concentrations were determined by ELISA. Non-parametric statistics was used for analyses.

RESULTS

(i) The median maternal plasma resistin concentration was higher in patients with pyelonephritis than in those with a normal pregnancy (P < 0.001); (ii) among patients with pyelonephritis, the median maternal resistin concentration did not differ significantly between those with and without a positive blood culture (P = 0.3); (iii) among patients with pyelonephritis who were diagnosed with systemic inflammatory response syndrome (SIRS), those who fulfilled > or =3 criteria for SIRS had a significantly higher median maternal plasma resistin concentration than those who met only two criteria; and (iv) maternal WBC count positively correlated with circulating resistin concentration (r = 0.47, P = 0.02).

CONCLUSION

Hyperresistinemia is a feature of acute pyelonephritis during pregnancy. The results of this study support the role of resistin as an acute-phase protein in the presence of bacterial infection during pregnancy.

Plasma resistin levels associate with risk for hypertension among nondiabetic women

Emerging evidence suggests a role for resistin in inflammation and vascular dysfunction, which may contribute to the pathogenesis of hypertension, but the association between resistin levels and incident hypertension is unknown. We examined the association between plasma resistin levels and the risk for incident hypertension among 872 women without a history of hypertension or diabetes from the Nurses' Health Study. We identified 361 incident cases of hypertension during 14 years of follow-up. After adjustment for potential confounders, resistin levels in the highest tertile conferred a 75% higher risk for hypertension than the lowest tertile (relative risk [RR] 1.75; 95% confidence interval [CI] 1.19 to 2.56). Further adjustment for other adipokines did not change the RR substantially. In stratified analysis, resistin levels in the highest tertile significantly increased the risk for hypertension among women aged >or=55 years (adjusted RR 2.40; 95% CI 1.55 to 3.73) but not among women aged <55 years (adjusted RR 0.64; 95% CI 0.25 to 1.62). In a subset analysis of 362 women who also had measurements of inflammatory and endothelial biomarkers, plasma resistin levels significantly correlated with IL-6, soluble TNF receptor 2, intercellular adhesion molecule 1, vascular adhesion molecule 1, and E-selectin after controlling for age and body mass index. After further adjustment for these biomarkers and C-reactive protein, resistin levels remained significantly associated with incident hypertension. In conclusion, higher plasma resistin levels independently associate with an increased risk for incident hypertension among women without diabetes.

Resistin competes with lipopolysaccharide for binding to toll-like receptor 4

Toll-like receptors (TLRs) are a family of cellular structures activated by recognition of pathogen associated molecular sequences. The activation of TLRs triggers a variety of intracellular mechanisms aiming to protect the host from the invading microorganisms. Lipopolysaccharide (LPS) is the main ligand for TLR4. Here we show that resistin, a cystein-rich protein believed to regulate carbohydrate metabolism, competes with LPS for binding to TLR4. Binding of recombinant resistin to human myeloid and epithelial cells was assessed by flow cytometry and its co-precipitation with TLR4 was demonstrated. Antibodies against TLR4 abolished resistin binding to human leucocytes and cytokine production by peripheral blood mononuclear cells in response to resistin stimulation. In contrast, isotype-matched murine IgG or TLR2 antibodies were unable to prevent binding of resistin to the cells. Similarly, TLR4-dependent pattern of resistin binding was observed in epithelial cell line HEK293 (human epithelial kidney cell), where TLR4 transfected, but not myeloid differentiation factor 2/CD14-transfected, TLR2 transfected or HEKnull cells, responded functionally to resistin stimulation. Intracellular signalling of resistin was assessed using inhibitors of transcription factors mitogen activated protein kinases, nuclear factor-kappaB, phosphoinositide 3-kinase and siRNA targeting TLR4 and human myeloid differentiation factor 88. Results demonstrate that TLR4 serves as a receptor for the pro-inflammatory effects of resistin in human cells. This may partly explain the multifunctional role of resistin in chronic inflammation, atherosclerosis and insulin resistance.

The role of resistin as a regulator of inflammation: Implications for various human pathologies

Resistin was originally described as an adipocyte-secreted peptide that induced insulin resistance in rodents. Increasing evidence indicates its important regulatory roles in various biological processes, including several inflammatory diseases. Further studies have shown that resistin in humans, in contrast to its production by adipocytes in mice, is synthesized predominantly by mononuclear cells both within and outside adipose tissue. Possible roles for resistin in obesity-related subclinical inflammation, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, rheumatic diseases, malignant tumors, asthma, inflammatory bowel disease, and chronic kidney disease have already been demonstrated. In addition, resistin can modulate several molecular pathways involved in metabolic, inflammatory, and autoimmune diseases. In this review, current knowledge about the functions and pathophysiological implications of resistin in different human pathologies is summarized, although there is a significant lack of firm evidence regarding the specific role resistin plays in the "orchestra" of the numerous mediators of inflammation.

Markers of insulin sensitivity in placentas and cord serum of intrauterine growth-restricted newborns

OBJECTIVE

Intrauterine growth restriction (IUGR) has been related to a higher incidence of insulin resistance in adult life, which is associated with low adiponectin and high resistin, insulin and interleukin (IL)-6 serum concentrations. This study assessed cortisol, insulin, total insulin receptor, resistin, adiponectin and IL-6 concentrations, as markers of insulin sensitivity, in placental lysates and cord serum of IUGR and appropriate for gestational age (AGA) newborns, to establish relationships among peptides and with growth parameters at birth.

DESIGN AND PATIENTS

Whole villous tissue and cord serum at birth were collected from 24 AGA and 18 IUGR newborns of comparable gestational age.

MEASUREMENTS

Hormonal and peptide concentrations were assayed in placental lysates and cord serum using specific commercial kits. Concentrations in lysates were adjusted per mg of total protein content.

RESULTS

Cortisol, insulin and resistin concentrations and the total amount of insulin receptor were similar in both groups. IL-6 concentration in lysates was significantly higher in IUGR compared with AGA newborns. Adiponectin was significantly lower in lysates from IUGR compared with AGA newborns. Placental insulin and resistin concentrations were positively correlated. Placental adiponectin concentration was positively correlated with the weight of the placenta, birthweight and head circumference. IL-6 concentration in lysates was negatively correlated with birth length, birthweight and head circumference.

CONCLUSIONS

This study evaluated the markers of insulin sensitivity in the placentas of subjects born IUGR, showing new potential roles for adiponectin and IL-6 in particular, and suggesting a role for the placenta in the programming of these hormones.

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.

High resistin and interleukin-6 levels are associated with gestational diabetes mellitus

Resistin is a cysteine-rich adipokine originally described as a molecular link between obesity and insulin resistance in rodents. In this study, we hypothesised that serum resistin concentrations are elevated in patients with gestational diabetes mellitus (GDM) when compared with pregnant women with normal glucose tolerance (NGT) and related to proinflammatory interleukin-6 (IL-6) and other factors conferring insulin resistance. Serum resistin and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA) in 81 women with GDM, 82 women with NGT between 24 and 31 weeks of gestation and 25 healthy non-pregnant women. Resistin concentrations were significantly higher in the GDM (21.9 [17.55-25.40] ng/ml) than in the NGT group (19.03 [15.92-23.91] ng/ml, p = 0.047), as well as in the non-pregnant women (14.8 [13.7-16.6] ng/ml, p < 0.0001). Serum IL-6 levels were elevated in the GDM (1.0 [0.7-1.5] pg/ml) as compared with the NGT group (0.8 [0.5-1.1] pg/ml, p = 0.006) and the non-pregnant controls (0.7 [0.5-1.1] pg/ml, p = 0.04). Multiple regression analysis revealed that in the pregnant women circulating resistin was related to serum IL-6 (beta = 0.33, p = 0.0004) but not to insulin or the index of insulin resistance. It is concluded that the finding of high resistin and IL-6 levels in women with gestational diabetes might confirm a role of low-grade inflammation in the pathogenesis of GDM.

Serum resistin correlates with central obesity but weakly with insulin resistance in Chinese children and adolescents

OBJECTIVE

Resistin has been linked with obesity and hypothesized as a potential marker of insulin resistance in addition to being linked with acute inflammation. However, these links are still highly controversial in humans. Our goal was to examine resistin levels in relation to obesity, insulin resistance and inflammation markers in a large population of Asian children and adolescents.

METHODS

Children and adolescents (n=3472) aged 6-18 years, boys (n=1765) and girls (n=1707), were assessed for body size parameters, pubertal development, blood lipids, glucose, insulin, resistin, C-reactive protein (CRP), adiponectin and complement C3 (C3) levels.

RESULTS

Resistin increased with central obesity in both genders but not with simple adiposity in boys. Several markers associated with central obesity correlated in a gender-specific fashion with plasma resistin. Waist circumference, fat-mass percentage, waist-to-height ratio and body mass index (BMI) positively correlated with resistin in both genders. Blood lipids such as triglycerides, nonesterified fatty acids (NEFA) and low-density lipoprotein cholesterol, diastolic and systolic blood pressure correlated positively with resistin in boys. NEFA, high-density lipoprotein cholesterol (negatively) and inflammation markers, such as CRP and C3, positively correlated with resistin in girls. There was no correlation between resistin and adiponectin, and no association of adiponectin with resistin quintiles in either boys or girls. In both boys and girls, resistin tended to decrease with age, with girls having higher levels than boys. Few indices of insulin resistance were linked with plasma resistin in either gender.

CONCLUSION

In this population, plasma resistin levels are a weak biochemical marker of metabolic dysfunction defined by central obesity, adiposity and inflammation and does not predict insulin resistance. Only a small proportion of resistin variation can be explained by factors related to metabolic syndrome, suggesting that resistin is not strongly implicated in a concentration-dependent fashion in any of the examined pathologies.

Intrauterine growth restriction and adult disease: the role of adipocytokines

Intrauterine growth restriction (IUGR) is the failure of the fetus to achieve his/her intrinsic growth potential, due to anatomical and/or functional disorders and diseases in the feto-placental-maternal unit. IUGR results in significant perinatal and long-term complications, including the development of insulin resistance/metabolic syndrome in adulthood. The thrifty phenotype hypothesis holds that intrauterine malnutrition leads to an adaptive response that alters the fetal metabolic and hormonal milieu designed for intrauterine survival. This fetal programming predisposes to an increased susceptibility for chronic diseases. Although the mechanisms controlling intrauterine growth are poorly understood, adipose tissue may play an important role in linking poor fetal growth to the subsequent development of adult diseases. Adipose tissue secretes a number of hormones, called adipocytokines, important in modulating metabolism and recently involved in intrauterine growth. This review aims to summarize reported findings concerning the role of adipocytokines (leptin, adiponectin, ghrelin, tumor necrosis factor (TNF), interleukin-6 (IL6), visfatin, resistin, apelin) in early life, while attempting to speculate mechanisms through which differential regulation of adipocytokines in IUGR may influence the risk for development of chronic diseases in later life.

Increased serum resistin concentration in patients with chronic pancreatitis: possible cause of pancreatic fibrosis

BACKGROUND

Resistin is an adipokine, which displays proinflammatory properties. Thus, it is likely that resistin can influence the course of chronic pancreatitis, and/or that chronic pancreatitis may affect the serum resistin concentration.

GOALS

The aim of the present study was to determine the serum resistin concentration in patients with chronic pancreatitis and to analyze the relationship between serum resistin concentration and serum concentrations of leptin (proinflammatory adipokine) and adiponectin (anti-inflammatory adipokine).

STUDY

A total of 23 male, nondiabetic patients with chronic pancreatitis of alcoholic origin and 16 healthy subjects were examined. Fasting blood samples were collected from patients in both groups. Serum resistin concentration was assayed by enzyme-linked immunosorbent assay. Serum adiponectin, leptin, and insulin concentrations were determined by radioimmunoassay.

RESULTS

Serum resistin concentration was significantly higher in patients with chronic pancreatitis as compared with control subjects. In contrast, patients with chronic pancreatitis had lower serum leptin and insulin concentrations than healthy subjects. There were no statistically significant differences in serum adiponectin concentration between patients with pancreatitis and healthy subjects.

CONCLUSIONS

The results presented in this paper indicate that chronic pancreatitis in human is associated with the increase in serum resistin concentration and with the decrease in serum leptin and insulin concentrations. It can be supposed that resistin, by stimulation of tumor necrosis factor-alpha synthesis in blood mononuclear cells and in macrophages, increases the concentration of tumor necrosis factor-alpha, which in turn activates stellate cells. Activated stellate cells can produce collagen, eventually resulting in the development of pancreatic fibrosis.

Resistin in amniotic fluid and its association with intra-amniotic infection and inflammation

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is one of the most important mechanisms of disease in preterm birth. Resistin is an adipocytokine that has been linked to insulin resistance, diabetes, obesity and inflammation. The objective of this study was to determine if resistin is present in amniotic fluid (AF) and if its concentration changes with gestational age, in the presence of labour, and in IAI in patients with spontaneous preterm labour (PTL) and intact membranes, preterm prelabour rupture of membranes (PPROM) and clinical chorioamnionitis.

STUDY DESIGN

This cross-sectional study included 648 patients in the following groups: (1) women in the mid-trimester of pregnancy (14-18 weeks) who underwent amniocentesis for genetic indications and delivered a normal neonate at term (n = 61); (2) normal pregnant women at term with (n = 49) and without (n = 50) spontaneous labour; (3) patients with an episode of PTL and intact membranes who were classified into: (a) PTL who delivered at term (n = 153); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 108); and (c) PTL with IAI (n = 84); (4) women with PPROM with (n = 47) and without (n = 44) IAI; and (5) patients with clinical chorioamnionitis at term with (n = 22) and without (n = 30) microbial invasion of the amniotic cavity. Resistin concentration in AF was determined by enzyme-linked immunoassay. Non-parametric statistics were used for analyses.

RESULTS

(1) Resistin was detected in all AF samples; (2) the median AF resistin concentration at term was significantly higher than in the mid-trimester (23.6 ng/mL vs. 10 ng/mL; p < 0.001); (3) among patients with PTL, the median AF resistin concentration was significantly higher in patients with IAI than in those without IAI (144.9 ng/mL vs. 18.7 ng/mL; p < 0.001) and those with PTL and intact membranes who delivered at term (144.9 ng/mL vs. 16.3 ng/mL; p < 0.001); (4) patients with PPROM with IAI had a significantly higher median AF resistin concentration than those without IAI (132.6 ng/mL vs. 13 ng/mL; p < 0.001); (5) no significant differences were observed in the median AF resistin concentration between patients with spontaneous labour at term and those at term not in labour (28.7 ng/mL vs. 23.6 ng/mL; p = 0.07); and (6) AF resistin concentration > or =37 ng/mL (derived from a receiver-operating characteristic curve) had a sensitivity of 85.4% and a specificity of 94.3% for the diagnosis of intra-amniotic inflammation.

CONCLUSIONS

Resistin is a physiologic constituent of the AF, and its concentrations in AF: (1) are significantly elevated in the presence of IAI; (2) increase with advancing gestation; and (3) do not change in the presence of spontaneous labour at term. We propose that resistin may play a role in the innate immune response against intra-amniotic infection.

Gene expression of placental hormones regulating energy balance in small for gestational age neonates

OBJECTIVE

Fetal growth restriction is associated with an increased risk for metabolic and cardiovascular disease in later life. To further elucidate mechanisms that might be involved in the process of prenatal programming, we measured the adipokines leptin, resistin, and adiponectin and the GH-releasing hormone ghrelin in the placenta of small for gestational age (SGA) neonates.

STUDY DESIGN

The control group included 24 placentas of appropriate for gestational age (AGA) newborns, in the study group were 16 placentas of SGA neonates. Gene expression of leptin, resistin, adiponectin, and ghrelin was examined. For hormones showing alterations in gene regulation placental protein expression was measured by Western blot.

RESULTS

Placental mRNA expression of leptin was significantly increased in SGA placentas (p=0.0035, related to beta-actin). Protein concentration was increased, as well. There were no differences in placental resistin, adiponectin, or ghrelin gene expressions between SGA neonates and controls. Leptin was the only hormone to demonstrate a significant inverse correlation with birth weight (r=-0.44, p=0.01). Adiponectin correlated significantly with leptin (r=0.53, p=0.0023) and ghrelin (r=0.50, p=0.0045).

CONCLUSIONS

Placental leptin gene expression and protein concentration showed the expected increase in the SGA group. Leptin was inversely correlated with birth weight. Positive correlation of adiponectin with leptin and ghrelin expression suggests an interaction between these hormones in the placenta. However, the unchanged expression of resistin, adiponectin, and ghrelin in SGA placentas and the absence of correlation with birth weight cast doubt whether these hormones produced in the placenta play a key role in fetal programming.

First trimester adipocytokine concentrations and risk of developing gestational diabetes later in pregnancy

OBJECTIVE

Adipocytokines are important regulators of insulin resistance. The aim of this study was to compare maternal adipocytokines in early pregnancy among women diagnosed with and without gestational diabetes (GDM) months later.

DESIGN

A nested case-control study.

PATIENTS

Adiponectin, resistin and interleukin-6 (IL-6) were measured in 59 nulliparous women (30 women with GDM and 29 controls) in plasma obtained in early pregnancy. Patients underwent routine testing for GDM in late pregnancy.

MEASUREMENTS

Adiponectin was measured using radioimmunoassay. Resistin and IL-6 were measured by ELISA. Statistical analysis included Student's t-test, logistic regression and Pearson's correlation.

RESULTS

Groups were not different by baseline descriptors or obstetric outcomes. Mean gestational age at sampling was 9.3 +/- 2.6 weeks. Adiponectin was lower (P < 0.001) in women who later developed GDM compared to controls (4.3 +/- 0.4 vs. 6.9 +/- 0.6 microg/ml). Adiponectin was negatively associated with the development of GDM (P = 0.002; OR: 0.70, 95% CI: 0.56, 0.88) and the association persisted in multivariable analysis controlling for confounders (P = 0.01; OR: 0.69, 95% CI: 0.52, 0.92). Women with first trimester adiponectin concentrations < 25th% were 10 times more likely to be diagnosed with GDM (OR 10.2; 95% CI 1.3, 78.7). Early adiponectin concentrations negatively correlated with BMI (P = 0.01; r = -0.32) and subsequent 50 g glucose challenge (P = 0.03; r =-0.29). Mean resistin and IL-6 concentrations were not different between the two groups.

CONCLUSIONS

Women with GDM have evidence of altered adipocyte function as measured by adiponectin early in pregnancy, months before the clinical diagnosis of GDM is traditionally made.

Resistin in serum is associated with higher levels of IL-1Ra in post-menopausal women with rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate associations between serum levels of resistin, an adipokine and markers of inflammation, bone metabolism, plasma lipids and kidney function in post-menopausal RA patients and to evaluate if HRT during 2 yrs affected resistin levels.

METHODS

Eighty-eight women were randomly allocated to receive HRT, vitamin D(3) and calcium or vitamin D(3) and calcium alone. Serum levels of resistin, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-6 soluble receptor, TNF-alpha were measured by ELISA, markers of bone metabolism, carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen by RIA, ESR, CRP, Hb, creatinine and lipids by standard laboratory techniques, BMD and total lean mass (TLM) by DXA and joint destruction by Larsen score. Resistin was also measured in 42 healthy control women.

RESULTS

There was no difference in resistin concentration between patients and healthy controls. Resistin was significantly correlated with IL-1Ra, CRP, TNF-alpha, ICTP, glucocorticosteroids and Larsen score and inversely with BMD, hip and with TLM. In multiple regression analysis, IL-1Ra, TLM and use of corticosteroids remained determinants of resistin. Patients treated with HRT displayed significant increase in resistin compared with controls in the first but not the second year.

CONCLUSIONS

Resistin was associated with increased inflammation, particularly by the acute-phase reactant IL-1Ra antagonizing IL-1beta, joint destruction, glucocorticosteroids and with reduced BMD and TLM. These findings suggest resistin being a significant mediator in the inflammatory process in RA. Further studies examining the mechanisms behind the relation between resistin and IL-1Ra are encouraged. HRT does not seem to have important long-term effect on resistin.

Expression of resistin protein in normal human subcutaneous adipose tissue and pregnant women subcutaneous adipose tissue and placenta

The expression of resistin protein in normal human abdominal, thigh, pregnant women abdominal, non-pregnant women abdominal subcutaneous adipose tissue and placenta and the relationship between obesity, type 2 diabetes mellitus (T2DM), pregnant physiological insulin resistance (IR) and gestational diabetes mellitus (GDM) was investigated. The expression of resistin protein in normal human abdominal, thigh, pregnant women abdominal, non-pregnant women abdominal subcutaneous adipose tissue and placenta was detected by using Western blotting method. Fasting serum glucose concentration was measured by glucose oxidase assay. Serum cholesterol (CHOL), serum triglycerides (TG), serum HDL cholesterol (HDL-C) and serum LDL cholesterol (LDL-C) were determined by full automatic biochemical instrument. Fasting insulin was measured by enzyme immunoassay to calculate insulin resistance index (IRI). Height, weight, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured to calculate body mass index (BMI) and body fat percentage (BF %). Resistin protein expression in pregnant women placental tissue (67 905 +/- 8441) (arbitrary A values) was much higher than that in subcutaneous adipose tissue in pregnant women abdomen (40 718 +/- 3818, P < 0.01), non-pregnant women abdomen (38 288 +/- 2084, P < 0.01), normal human abdomen (39 421 +/- 6087, P < 0.01) and thigh (14 942 +/- 6706, P < 0.001) respectively. The resistin expression in abdominal subcutaneous adipose tissue showed no significant difference among pregnant, non-pregnant women and normal human, but much higher than that in thigh subcutaneous adipose tissue (P < 0.001). Pearson analysis revealed that resistin protein was correlated with BMI (r = 0.42), fasting insulin concentration (r = 0.38), IRI (r = 0.34), BF % (r = 0.43) and fasting glucose (r = 0.39), but not with blood pressure, CHOL, TG, HDL-C and LDL-C. It was suggested that resistin protein expression in human abdominal subcutaneous adipose tissue was much higher than that in human thigh subcutaneous adipose tissue. Resistin was closely related with central obesity, leading to IR, subsequently obesity and T2DM. Resistin protein expression in placental tissue was much higher than that in subcutaneous adipose tissue in normal human abdomen, pregnant abdomen, non-pregnant women abdomen and thigh. It was indicated that resistin protein could be secreted from human placental tissue. Resistin might be one of the factors that lead to pregnant physiological IR and GDM.

Effects of aging and calorie restriction on the global gene expression profiles of mouse testis and ovary

Background

The aging of reproductive organs is not only a major social issue, but of special interest in aging research. A long-standing view of 'immortal germ line versus mortal soma' poses an important question of whether the reproductive tissues age in similar ways to the somatic tissues. As a first step to understand this phenomenon, we examine global changes in gene expression patterns by DNA microarrays in ovaries and testes of C57BL/6 mice at 1, 6, 16, and 24 months of age. In addition, we compared a group of mice on ad libitum (AL) feeding with a group on lifespan-extending 40% calorie restriction (CR).

Results

We found that gene expression changes occurred in aging gonads, but were generally different from those in somatic organs during aging. For example, only two functional categories of genes previously associated with aging in muscle, kidney, and brain were confirmed in ovary: genes associated with complement activation were upregulated, and genes associated with mitochondrial electron transport were downregulated. The bulk of the changes in gonads were mostly related to gonad-specific functions. Ovaries showed extensive gene expression changes with age, especially in the period when ovulation ceases (from 6 to 16 months), whereas testes showed only limited age-related changes. The same trend was seen for the effects of CR: CR-mediated reversal of age-associated gene expression changes, reported in somatic organs previously, was limited to a small number of genes in gonads. Instead, in both ovary and testis, CR caused small and mostly gonad-specific effects: suppression of ovulation in ovary and activation of testis-specific genes in testis.

Conclusion

Overall, the results are consistent with unique modes of aging and its modification by CR in testis and ovary.

Resistin modulates glucose uptake and glucose transporter-1 (GLUT-1) expression in trophoblast cells

The adipocytokine resistin impairs glucose tolerance and insulin sensitivity. Here, we examine the effect of resistin on glucose uptake in human trophoblast cells and we demonstrate that transplacental glucose transport is mediated by glucose transporter (GLUT)-1. Furthermore, we evaluate the type of signal transduction induced by resistin in GLUT-1 regulation. BeWo choriocarcinoma cells and primary cytotrophoblast cells were cultured with increasing resistin concentrations for 24 hrs. The main outcome measures include glucose transport assay using [³H]-2-deoxy glucose, GLUT-1 protein expression by Western blot analysis and GLUT-1 mRNA detection by quantitative real-time RT-PCR. Quantitative determination of phospho(p)-ERK1/2 in cell lysates was performed by an Enzyme Immunometric Assay and Western blot analysis. Our data demonstrate a direct effect of resistin on normal cytotrophoblastic and on BeWo cells: resistin modulates glucose uptake, GLUT-1 messenger ribonucleic acid (mRNA) and protein expression in placental cells. We suggest that ERK1/2 phosphorylation is involved in the GLUT-1 regulation induced by resistin. In conclusion, resistin causes activation of both the ERK1 and 2 pathway in trophoblast cells. ERK1 and 2 activation stimulated GLUT-1 synthesis and resulted in increase of placental glucose uptake. High resistin levels (50–100 ng/ml) seem able to affect glucose-uptake, presumably by decreasing the cell surface glucose transporter.

Adipokines and insulin resistance during pregnancy

Normal pregnancy has been characterized as a "diabetogenic state". On the other hand, the adipose tissue is now considered an active organ, capable of secreting substances such as adipokines, which may play a role in the pathogenesis of insulin resistance. Resistin, leptin serum and placental levels increase as pregnancy progresses, which is in contrast to levels of adiponectin. These levels correlate with the state of reduced insulin sensitivity often developed in the latter stages of pregnancy. The objective of this article is to review recent advances in our understanding of adipokines and insulin resistance during pregnancy.

Perinatal changes of plasma resistin concentrations in pregnancies with normal and restricted fetal growth

BACKGROUND

The adipocytokine resistin inhibits adipogenesis and induces insulin resistance. Intrauterine growth-restricted (IUGR) neonates have reduced fat mass and changes of endocrine/metabolic mechanisms, predisposing to insulin resistance and metabolic syndrome in adult life.

OBJECTIVES

To investigate plasma resistin concentrations in maternal, fetal and neonatal samples from IUGR and appropriate-for-gestational-age (AGA) pregnancies and correlate them with respective insulin concentrations.

METHODS

Plasma resistin and insulin concentrations were determined in 40 mothers and their 20 IUGR and 20 AGA singleton full-term fetuses and neonates on postnatal day 1 (N1) and day 4 (N4).

RESULTS

No significant differences in resistin concentrations were observed between AGA and IUGR groups. In the AGA group, maternal resistin concentrations were significantly lower compared to fetal, N1 and N4 ones (p = 0.003, p = 0.017 and p = 0.039, respectively). Maternal resistin concentrations positively correlated with fetal ones (r = 0.527, p = 0.02). In the IUGR group, maternal resistin concentrations were significantly lower compared to N1 (p < 0.001) and positively correlated with N4 concentrations (r = 0.626, p = 0.007). In both groups, the effect of gender, mode of delivery, parity and adjusted birth weight (customized centiles) on resistin concentrations was not significant. No correlation between resistin and insulin concentrations was documented.

CONCLUSIONS

Lack of difference in resistin concentrations between IUGR and AGA groups, and lack of correlation between resistin and insulin concentrations as well as customized centiles, possibly suggests that resistin may not be directly involved in the regulation of insulin sensitivity and adipogenesis in the perinatal period. Mode of delivery and parity are not associated with circulating resistin concentrations.

Serum resistin in gestational diabetes mellitus and early postpartum

OBJECTIVES

To observe the alterations in serum resistin in gestational diabetes (GDM) and the early postpartum period, and compare this to nondiabetic pregnancies in order to evaluate the role of serum resistin in gestational diabetes mellitus.

DESIGN

A cross-sectional study.

PATIENTS

Twenty women with normal pregnancy and 20 with gestational diabetes.

MEASUREMENTS

Serum resistin concentration was assayed by ELISA.

RESULTS

Serum resistin concentration was significantly higher in women with GDM than in controls before delivery. Serum levels of resistin significantly decreased after delivery in both the GDM group and controls (P < 0.001 for both). There was a trend of higher serum resistin in women with GDM than in controls. Differences existed on days 1 (P < 0.001) and 3 (P = 0.013), but not by day 5 (P = 0.052) after delivery.

CONCLUSIONS

Elevated serum resistin level was observed in women with gestational diabetes, suggesting that it is important in the pathology of the disease.

The interplay between nutrients and the adipose tissue

The importance of adipose tissue in health as well as disease has been demonstrated in several studies recently, and it has become appropriate to use the term 'adipose organ' when referring to adipose tissue as a whole. The obesity epidemic, with a marked increase in the incidence of the metabolic syndrome leading to diabetes type 2 as well as cardiovascular complications, has stimulated considerable interest in adipose tissue biology. Moreover, several studies in different species have shown that limited energy intake is associated with less inflammation, improved biomarkers of health and a marked increase in longevity. In addition, there is convincing evidence that an optimal amount of adipose tissue is essential for many body functions such as immune response, reproduction and bone quality. Some nutrients and their metabolites are important as energy sources as well as ligands for many transcription factors expressed in adipose tissue, including all energy-providing nutrients both directly and indirectly as well as cholesterol, vitamin E and vitamin D. In particular, fatty acids can be effectively taken up by adipocytes and they can interact with several transcription factors crucial for growth, development and metabolic response, e.g. PPARalpha, -delta and -gamma, sterol regulatory element-binding proteins1 and 2 and liver X receptors alpha and beta). Moreover, glucose is also readily taken up and stored as fatty acids via lipogenesis in adipocytes. It is known that some metabolic signals released as proteins from adipose tissue (adipokines) are important for normal as well as pathological responses to the amount of energy stored in the adipose organ. The future challenge will be to understand the function of adipose tissue in energy homeostasis and the interplay with nutrients in order to be able to give optimal advice for the prevention and treatment of obesity.

Expression and regulation of resistin in osteoblasts and osteoclasts indicate a role in bone metabolism

The adipose tissue is the site of expression and secretion of a range of biologically active proteins, called adipokines, for example, leptin, adiponectin, and resistin. Leptin has previously been shown to be expressed in osteoblasts and to promote bone mineralization, whereas adiponectin expression is enhanced during osteoblast differentiation. In the present study we explored the possible role of resistin in bone metabolism. We found that resistin is expressed in murine preosteoclasts and preosteoblasts (RAW 264.7, MC3T3-E1), in primary human bone marrow stem cells and in mature human osteoblasts. The expression of resistin mRNA in RAW 264.7 was increased during differentiation and seemed to be regulated through PKC- and PKA-dependent mechanisms. Recombinant resistin increased the number of differentiated osteoclasts and stimulated NFkappaB promoter activity, indicating a role in osteoclastogenesis. Resistin also enhanced the proliferation of MC3T3-E1 cells in a PKA and PKC-dependent manner, but only weakly interfered with genes known to be upregulated during differentiation of MC3T3-E1 into osteoblasts. All together, our results indicate that resistin may play a role in bone remodeling.

Study of Resistin gene expression in peripheral blood mononuclear cell and its gene polymorphism in a small range population

OBJECTIVE

To observe the expression of Resistin mRNA in peripheral blood mononuclear cells and its gene polymorphism in coding region in a small range population in Zhejiang Province of China.

METHODS

Eighty-three cases of type 2 diabetes mellitus and 53 healthy people were included. The expression of Resistin mRNA in peripheral blood mononuclear cells was detected by RT-PCR and semi-quantitative PCR assay. The sequencing work was done in Resistin cDNA and gene polymorphism was analyzed.

RESULTS

At the same condition, in 83 diabetes patients, Resistin mRNA was detected in 23 cases (11 males and 12 females). There was no Resistin mRNA expression in 53 healthy people. The ratio of PCR products between Resistin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was from 0.564 to 1.238, averaging 0.804+/-0.436. The sequence of Resistin cDNA is almost identical with each other and with that in GenBank with no single nucleotide polymorphism being found.

CONCLUSION

Resistin mRNA is expressed in human peripheral blood mononuclear cells in some type 2 diabetes mellitus, but its expression is at a low level. Among the experiment population we did not find polymorphism phenomenon in Resistin coding region. The different individual's Resistin coding region is highly coincident.

Maternal and foetal resistin and adiponectin concentrations in normal and complicated pregnancies

OBJECTIVE

The aim of this study was to evaluate how resistin and adiponectin (ApN) are involved in maternal energy metabolism and foetal growth.

DESIGN

A cross-sectional study.

PATIENTS AND MEASUREMENTS

Resistin and ApN were measured in 30 healthy nonpregnant women, 73 pregnant women [10-41 weeks of gestation; 18 with gestational diabetes mellitus (GDM), five with pregnancy-induce hypertension (PIH), nine with pre-eclampsia (PE), eight with chronic hypertension (CH) and 33 normal] and 40 foetal samples (20-41 weeks of gestation; 18 from GDM mothers and 22 from normal mothers).

RESULTS

Resistin levels were significantly higher in normal pregnant women than in nonpregnant controls (13.7 +/- 2.1 vs. 6.3 +/- 1.6 ng/ml; P < 0.005) and showed a negative correlation with gestational age (P < 0.0001, r = -0.7). Only women with PE presented resistin levels significantly lower than normotensive women of the same gestational age (8.2 +/- 1.2 vs. 17.9 +/- 4.3 ng/ml; P < 0.005). ApN levels, although similar in normal pregnant women to those in nonpregnant controls, were significantly lower in women with GDM (37-41 weeks; 5.2 +/- 0.5 vs. 8.2 +/- 0.8 mg/l; P < 0.0001) and PE (20-37 weeks; 5.0 +/- 0.7 vs. 9.5 +/- 0.7 mg/l; P = 0.008) than those found in normal women matched for gestational age. Resistin was detected in the umbilical venous blood in foetuses from 20 to 41 weeks of gestation. In all newborns, both resistin and ApN levels were significantly higher than those recorded in adult life and did not correlate with maternal levels (P = ns, r = 0.03 for resistin and P = ns, r = -0.3 for ApN). Foetuses from diabetic mothers had ApN significantly lower than normal foetuses (26.8 +/- 2.6 vs. 37.5 +/- 3.5 mg/l; P = 0.02), while resistin levels were similar (17.3 +/- 3.7 vs. 18.2 +/- 1.5 ng/ml; P = ns).

CONCLUSION

The secretion pattern of ApN in normal and complicated pregnancies strongly suggests an involvement of ApN in insulin resistance during gestation, while resistin seems to have a minor role. Moreover, the detection of high levels of resistin and ApN in cord blood during gestation is consistent with a regulatory action of these adipokines on tissue differentiation and foetal growth.

Resistin: a hormone which induces insulin resistance is increased in normal pregnancy

AIMS

Resistin, a newly discovered adipokine, is thought to play a key role in the regulation of insulin resistance. The objectives of this study were to develop a nomogram of maternal plasma concentrations of resistin from 11 weeks of gestation to term and to determine whether resistin concentrations differ between normal and overweight pregnant women.

METHODS

In this cross-sectional study, plasma concentrations of resistin were determined in normal pregnant women of normal body mass index (BMI 18.5-24.9; n=261), overweight pregnant women (BMI > or =25; n=140), and non-pregnant women of normal BMI (n=40). Blood samples were collected once from each woman between the first trimester and term. Percentiles for resistin concentration were determined for five pre-specified windows of gestational age. Plasma resistin concentration was determined by immunoassay. Non-parametric statistics were used for analysis.

RESULTS

The median maternal plasma concentration of resistin between 11 to 14 weeks of gestation in women of normal weight was significantly higher than non-pregnant women; the plasma concentration of resistin increased with gestational age.

CONCLUSIONS

Normal pregnant women have a higher median plasma concentration of resistin than non-pregnant women and the concentration of this adipokine increases with advancing gestation. Alterations in the maternal plasma concentration of resistin during pregnancy could contribute to metabolic changes of pregnancy.

Resistin worsens cardiac ischaemia-reperfusion injury

We provide the first report of direct effects of resistin upon haemodynamic and neurohumoral parameters in isolated perfused rat heart preparations. Pre-conditioning with 1 nmol L-1 recombinant human resistin prior to ischaemia significantly impaired contractile recovery during reperfusion, compared with vehicle-infused hearts (P<0.05, n=12). This was accompanied by a significant increase in both A-type and B-type natriuretic peptides (P<0.05, n=12 both ANP and BNP vs vehicle), creatine kinase, and tumour necrosis factor-alpha (TNF-alpha) release in resistin-infused hearts. Resistin had no significant effect on myocardial glucose uptake. Co-infusion of resistin with Bay 11 7082 (an NF-kappaB inhibitor) improved contractile recovery following ischaemia and reduced both natriuretic peptide and creatine kinase release. This is the first evidence indicating resistin impairs cardiac recovery following ischaemia, stimulates cardiac TNF-alpha secretion, and modulates reperfusion release of natriuretic peptides and biochemical markers of myocardial damage. A TNF-alpha signalling related mechanism is suggested as one component underlying these effects.

Inflammation and pre-eclampsia

Pre-eclampsia is a common and potentially dangerous disorder of human pregnancy. The maternal syndrome of hypertension, proteinuria and oedema is part of a severe systemic inflammatory response that includes leukocyte and endothelial cell activation. Although the origins of pre-eclampsia remain unclear, a major cause is the failure to develop an adequate blood supply to the placenta, leading to placental oxidative stress. This results in the excess release of placental factors, such as syncytiotrophoblast debris or soluble fms-like tyrosine kinase-1 (sFlt-1), the soluble receptor for vascular endothelial growth factor (VEGF), into the maternal circulation, where they trigger an inflammatory response and endothelial dysfunction. Alternatively, pre-eclampsia can develop in the presence of a normal placenta in women that are susceptible to systemic inflammation, such as with chronic cardiovascular disease or diabetes. While clinical management of pre-eclampsia does not currently include anti-inflammatory agents, current research is focusing on ways to reduce inflammation and oxidative stress.