Circulating adipokines and mRNA expression in adipose tissue and the placenta in women with gestational diabetes mellitus.

Maternal adipose tissue and the placenta secrete various molecules commonly called adipokines such as chemerin, omentin-1, visfatin, adiponectin, and leptin that are important players in the pathogenesis of insulin resistance. Gestational diabetes mellitus (GDM) is defined as a state of glucose intolerance characterized by ß-cell dysfunction and insulin resistance. To examine whether circulating adipokines and their mRNA expression in the adipose tissue and the placenta are altered in GDM pregnancy, we compared 15 GDM women [obese (BMI > 30) and non-obese (BMI < 30)] to 23 NGT (normal glucose tolerance) women [obese and non-obese], at the time of the Cesarean section. Circulating chemerin and leptin were higher (p = 0.009 and p = 0.005, respectively) and circulating omentin-1, visfatin, as well as the adiponectin/leptin ratio were lower (p = 0.039, p = 0.007 and p = 0.011, respectively) in GDM-obese compared to NGT-non-obese women. Chemerin and leptin correlated positively with BMI and HOMA-IR and omentin-1 correlated negatively with BMI. Serum TNF-α was significantly elevated in all obese compared to non-obese pregnant women and correlated positively with BMI. Adiponectin levels were reduced -although not significantly- in GDM- and NGT-obese women compared to their non-obese counterparts. Resistin, RPB4 and IL-6 levels did not differ significantly between groups. Chemerin mRNA expression in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) was significantly higher compared to placenta in all women (6-to 24-times, p < 0.05). Chemerin-VAT mRNA expression in GDM-obese tended to be significantly higher compared to NGT-non-obese women (3-times, p = 0.005). Omentin-1 mRNA expression was significantly higher in VAT compared to SAT (50- to 100-times, p < 0.01) and its expression in placenta was negligible in all women. Although, leptin was expressed significantly higher in SAT compared to VAT and the placenta in all women (5- to 46-times, p < 0.05), only its mRNA expression in VAT of obese (GDM and NGT) differed significantly when compared to NGT-non-obese women (3-times higher, p < 0.02). Visfatin mRNA expression was comparable in all tissues. In conclusion, chemerin and leptin are elevated and omentin-1 and visfatin levels are decreased in GDM women complicated by obesity. This finding together with the positive association of chemerin and leptin with markers of insulin resistance, suggests that these adipokines and more especially chemerin and leptin accompanied by their adipose tissue expression could contribute to the increased insulin resistance and low grade inflammation that characterizes GDM-obese women.

Cytokines, diabetes mellitus and psychopathology: a challenging combination.

OBJECTIVES: The aim of this study was to investigate the association of IL-6, IL-12, and TNF-α with trait and state psychological factors in type 2 diabetic patients. DESIGN: Patients were divided in two groups. Group A consisted of 86 controlled diabetic patients (HbA1c<7) and the Group B consisted of 45 uncontrolled diabetic patients (HbA1c ≥ 7). SETTINGS: During the initial phase of the study (T0), blood samples were taken for measuring IL-6, IL-12 and TNF-α serum levels as well as a battery of psychometric instruments. One year later (T1), the uncontrolled diabetic patients were re-evaluated with the use of the same psychometric instruments and with the identical blood analysis. RESULTS: The average values of tnf-α were significantly different among controlled (7.73 ± 5.51) and uncontrolled patients (9.29 ± 4.52) at a significance level of 5% (p=0.009). Controlled diabetic patients show a statistically significant relationship between IL-6 and neuroticism (rp=0.303, p=0.010), and between IL-12 and psychotism, (rsp=0.382, p=0.001). Controlled diabetic patients show a statistically significant relationship between IL-12 and the act out hostility (rsp=-0.307, p=0.009). The scores of the psychometric tests differ significantly between the first and second evaluation. Acting out hostility and the direction of hostility increased when HbA1c values fell below the threshold of 7, while the total hostility index, as well as all other scales, dropped when patients controlled their metabolic profile. CONCLUSIONS: The present results provide evidence that IL-6, IL-12 and TNF-α are closely related to the course and treatment of type 2 diabetes.

High insulin and leptin increase resistin and inflammatory cytokine production from human mononuclear cells.

Resistin and the proinflammatory cytokines, such as TNF- α , IL-6, and IL-1 ß , produced by adipocytes, and macrophages, are considered to be important modulators of chronic inflammation contributing to the development of obesity and atherosclerosis. Human monocyte-enriched mononuclear cells, from ten healthy individuals, were exposed to high concentrations of insulin, leptin, and glucose (alone or in combination) for 24 hours in vitro. Resistin, TNF- α , IL-6, and IL-1 ß production was examined and compared to that in untreated cells. High insulin and leptin concentrations significantly upregulated resistin and the cytokines. The subsequent addition of high glucose significantly upregulated resistin and TNF- α mRNA and protein secretion, while it did not have any effect on IL-6 or IL-1 ß production. By comparison, exposure to dexamethasone reduced TNF- α , IL-6, and IL-1 ß production, while at this time point it increased resistin protein secretion. These data suggest that the expression of resistin, TNF- α , IL-6, and IL-1 ß from human mononuclear cells, might be enhanced by the hyperinsulinemia and hyperleptinemia and possibly by the hyperglycemia in metabolic diseases as obesity, type 2 diabetes, and atherosclerosis. Therefore, the above increased production may contribute to detrimental effects of their increased adipocyte-derived circulating levels on systemic inflammation, insulin sensitivity, and endothelial function of these patients.

Arterial stiffness is associated with increased monocyte expression of adiponectin receptor mRNA and protein in patients with coronary artery disease.

BACKGROUND: Arterial stiffness and carotid intima-media thickness (IMT) constitute validated cardiovascular prognostic markers. Adiponectin and its receptors 1 (AdipoR1) and 2 (AdipoR2) are involved in coronary artery disease (CAD). We investigated whether AdipoR1 and R2 mRNA and protein expression are associated with arterial stiffness, IMT and extent of coronary atherosclerosis. METHODS: We studied 71 patients (61 men, 10 women) with angiographically proven CAD. We measured: (i) monocyte expression of AdipoR1 and AdipoR2 mRNA (quantitative real-time PCR) and protein expression (flow cytometry) (iii) adiponectin, metalloproteinase-9 (MMP-9) and C-reactive protein (CRP) blood levels, (iv) carotid-femoral artery pulse wave velocity (PWV) and carotid IMT. RESULTS: Patients with multi-vessel CAD had higher AdipoR1 and AdipoR2 mRNA than those with single-vessel (P < 0.05). PWV was associated with AdipoR1 mRNA (r = 0.474), AdipoR1 protein (r = 0.228), AdipoR2 mRNA (r = 0.716), AdipoR2-protein (r = 0.261), adiponectin (r = 0.236), and MMP-9 (r = 0.350) (P < 0.05, for all correlations). After adjustment for age, sex, waist-hip ratio, and mean blood pressure both AdipoR1 and AdipoR2 mRNA remained independent determinants of PWV (R(2) = 0.35 and R(2) = 0.57, P < 0.05). IMT was also associated with AdipoR2 mRNA, AdipoR2 protein, and MMP-9 (P < 0.05). Increased expression of ADR2 mRNA significantly related to MMP-9 (r = 0.210), and CRP (r = 0.531) (P < 0.05). CONCLUSION: Increased mRNA and protein expression of adiponectin receptors is related with increased aortic stiffness, coronary and peripheral atherosclerosis in patients with CAD. The interrelation of AdipoR2 with inflammatory markers, PWV and IMT suggests a compensatory increase of these receptors to counteract the excess inflammatory and atherogenic process in CAD. Thus, adiponectin receptors may provide a potential therapeutic target of agents activating their beneficial action.American Journal of Hypertension 2012; doi:10.1038/ajh.2012.42.

Adiponectin levels and expression of adiponectin receptors in isolated monocytes from overweight patients with coronary artery disease.

BACKGROUND: Adiponectin has insulin-sensitizing and anti-atherosclerotic effects, partly mediated through its action on monocytes. We aimed to determine adiponectin levels and expression of its receptors (AdipoR1 and AdipoR2) in peripheral monocytes from overweight and obese patients with coronary artery disease (CAD). METHODS: Fifty-five overweight/obese patients, suspected for CAD, underwent coronary angiography: 31 were classified as CAD patients (stenosis ≥ 50% in at least one main vessel) and 24 as nonCAD. Quantitative RT-PCR and flow cytometry were used for determining mRNA and protein surface expression of adiponectin receptors in peripheral monocytes. A high sensitivity multiplex assay (xMAP technology) was used for the determination of plasma adiponectin and interleukin-10 (IL-10) secreted levels. RESULTS: Plasma adiponectin levels were decreased in CAD compared to nonCAD patients (10.9 ± 3.1 vs. 13.8 ± 5.8 µg/ml respectively, p = 0.033). In multivariable analysis, Matsuda index was the sole independent determinant of adiponectin levels. AdipoR1 and AdipoR2 protein levels were decreased in monocytes from CAD compared to nonCAD patients (59.5 ± 24.9 vs. 80 ± 46 and 70.7 ± 39 vs. 95.6 ± 47.8 Mean Fluorescence Intensity Arbitrary Units respectively, p < 0.05). No significant differences were observed concerning the mRNA levels of the adiponectin receptors between CAD and nonCAD patients. AdipoR2 protein levels were positively correlated with plasma adiponectin and Matsuda index (r = 0.36 and 0.31 respectively, p < 0.05 for both). Furthermore, basal as well as adiponectin-induced IL-10 release was reduced in monocyte-derived macrophages from CAD compared to nonCAD subjects. CONCLUSIONS: Overweight patients with CAD compared to those without CAD, had decreased plasma adiponectin levels, as well as decreased surface expression of adiponectin receptors in peripheral monocytes. This fact together with the reduced adiponectin-induced IL-10 secretion from CAD macrophages could explain to a certain extent, an impaired atheroprotective action of adiponectin.

Genetic variation in the adiponectin receptor 2 (ADIPOR2) gene is associated with coronary artery disease and increased ADIPOR2 expression in peripheral monocytes.

BACKGROUND: Adiponectin is an adipose tissue secreted protein known for its insulin sensitising and anti-atherogenic actions. To this date two adiponectin receptors have been discovered, adiponectin receptor 1 (ADIPOR1) and adiponectin receptor 2 (ADIPOR2). The aim of this study was to investigate the association of ADIPOR2 gene variations with coronary artery disease (CAD). METHODS: Eight common single nucleotide polymorphisms (SNPs) spanning the entire ADIPOR2 locus were chosen to perform association studies with anthropometric and metabolic parameters in a Greek population. They were classified as either CAD (stenosis >50% in at least one main vessel) or non-CAD individuals in accordance with coronary angiography data.Genotyping was performed using a microsphere-based suspension array and the Allele Specific Primer Extension (ASPE) method. Expression of ADIPOR2 protein and mRNA in circulating CD14+ monocytes were determined using flow cytometry and real time Polymerase Chain Reaction assays respectively. RESULTS: There was a significant difference in the distribution of genotypes of polymorphism rs767870 of ADIPOR2 between CAD and non-CAD individuals (p = 0.017). Furthermore, heterozygotes of the rs767870 polymorphism had significantly lower Flow Mediated Dilatation (FMD) values, higher values of Intima-Media Thickness (IMT) and increased ADIPOR2 protein levels in peripheral monocytes, compared to homozygotes of the minor allele after adjustment for age, sex, waist to hip ratio and HOMA. CONCLUSIONS: Our findings suggest that variants of ADIPOR2 could be a determinant for atherosclerosis independent of insulin resistance status, possibly by affecting ADIPOR2 protein levels.

Peripheral mononuclear cell resistin mRNA expression is increased in type 2 diabetic women.

Resistin has been shown to cause insulin resistance and to impair glucose tolerance in rodents, but in humans its physiological role still remains elusive. The aim of this study was to examine whether resistin mRNA expression in human peripheral mononuclear cells (PBMCs) and its corresponding plasma levels are altered in type 2 diabetes. Resistin mRNA levels were easily detectable in human PBMC, and found to be higher in DM2 compared to healthy women (P = .05). Similarly, mononuclear mRNA levels of the proinflammatory cytokines IL-1beta, TNF-alpha, and IL-6 were all significantly higher in DM2 compared to control women (P < .001). The corresponding plasma resistin levels were slightly, but not significantly, increased in DM2 women (P = .051), and overall, they correlated significantly with BMI (r = 0.406, P = .010) and waist circumference (r = 0.516, P = .003), but not with fasting insulin levels or HOMA-IR. Resistin mRNA expression is increased in PBMC from DM2 women, together with increased expression of the inflammatory cytokines IL-1beta, TNF-alpha, and IL-6, independent of obesity. These results suggest that resistin and cytokines might contribute to the low-grade inflammation and the increased atherogenic risk observed in these patients.

Stress, the endoplasmic reticulum, and insulin resistance.

Stress, such as nutrient deprivation, viral infections, inflammation, heat shock, or lipid accumulation, imposes a serious threat to the body. These stimuli, acting both on the central control stations of the stress system and its final effectors, catecholamines and glucocorticoids, and on the peripheral target tissues, can modulate insulin action in the body. Metabolic complications, such as diabetes, visceral obesity, and atherosclerosis have emerged as major health threats in the modern societies. Indeed, obesity and atherosclerosis are regarded as states of chronic low-grade inflammation, while inflammatory mediators and lipid accumulation can evoke a chronic stress at the cellular level, principally affecting the endoplasmic reticulum (ER). It has recently been shown that ER responds to metabolic stressors through a well coordinated molecular response that involves the transcriptional activation of multiple genes, the attenuation of protein synthesis and degradation of the ER-localized misfolded proteins, and the onset of apoptosis. This article examines the emerging role of stress on ER and its possible link with obesity, insulin resistance, and type 2 diabetes.

Compound heterozygosity of a frameshift mutation in the coding region and a single base substitution in the promoter of the ACTH receptor gene in a family with isolated glucocorticoid deficiency.

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive syndrome characterized by glucocorticoid insufficiency without mineralocorticoid deficiency. Mutations in the coding region of the ACTH receptor (MC2R) have been reported in several families with IGD. We amplified and sequenced the entire MC2R coding region in a new family with IGD. The proband was found to be heterozygous (paternal allele) for the mutation Gly217fs, which changes the open reading frame of the MC2R protein resulting in a truncated receptor. No other abnormality was found in the MC2R coding region. However, sequencing of the promoter region of the MC2R gene (-1017/44 bp) of the proband revealed a heterozygous T-->C substitution in the maternal allele at -2 bp position from initiation of the transcription start site. This substitution was found in only 6.5% in a healthy unrelated population. Constructs containing this polymorphism consistently showed a significant 15% decrease in promoter activity compared to wild type. In conclusion, we provide evidence that the IGD in this previously unreported family with ACTH resistance appears to be secondary to compound heterozygosity of a coding region and a promoter mutation in the MC2R gene.

Expression of leptin receptors in mononuclear cells from myelodysplastic syndromes and acute myeloid leukemias.

Leptin, the adipocyte hormone, and its receptor have been implicated in the differentiation/proliferation of hematopoietic cells. Given that the deregulated expression of a variety of growth factors and/or their receptors has been implicated in the pathogenesis of certain leukemias, we aimed to characterize the potential differences in the expression pattern of the two major leptin receptor transcript variants in peripheral blood mononuclear cells (PBMC) between different hematologic malignancies. Using RT-PCR and Southern blotting, we compared the expression levels of the two major leptin receptors, the longest (OB-R(L)) and the shortest (OB-R(S)) splice variants, in PBMC from patients with myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), healthy individuals and two human hematopoietic cell lines (HL-60 and K562). Expression of the OB-R(S) transcript clearly exceeded that of OB-R(L) in all patients and controls and in the HL-60 cells, but this was reversed in the K562 cell line. However, the expression of the OB-R(L) was significantly lower in MDS compared to controls and tended to be so in AML, while OB-R(S) tended to be higher in MDS and AML patients compared to controls, but this difference was not significant. Serum leptin levels and circulating soluble leptin receptor levels were slightly but not significantly higher in AML and MDS. These alterations in the expression of the leptin receptor isoforms in MDS and AML patients could suggest a potential role of leptin and its signaling in hematopoietic malignancies, which requires further examination.

The upstream regulatory region of the gene for the human homologue of the adhesion molecule TAG-1 contains elements driving neural specific expression in vivo.

Cell adhesion molecules (CAMs) of the immunoglobulin superfamily (IgSF) exhibit restricted spatial and temporal expression profiles requiring a tight regulatory program during development. The rodent glycoprotein TAG-1 and its orthologs TAX-1 in the human and axonin-1 in chick are cell adhesion molecules belonging to the contactin/F3 subgroup of the IgSF. TAG-1 is expressed in restricted subsets of central and peripheral neurons, not only during development but also in adulthood, and is implicated in neurite outgrowth, axon guidance and fasciculation, as well as neuronal migration. In an attempt to identify the regulatory elements that guide the neuronal expression of TAG-1, we have isolated genomic clones containing 4 kb of the TAX-1 upstream sequence and used them to drive the expression of the LacZ reporter gene in transgenic mice. We demonstrate that this sequence includes elements not only sufficient to restrict expression to the nervous system, but also to recapitulate to a great extent the endogenous pattern of the TAG-1 expression in the developing CNS.