Circulating Pro-Neurotensin in gestational diabetes mellitus.

BACKGROUND AND AIMS: Pro-Neurotensin (NT), a stable surrogate parameter of NT, has recently been introduced as a peptide predicting the development of obesity, diabetes mellitus, cardiovascular diseases, and cardiovascular mortality. However, regulation of Pro-NT in gestational diabetes mellitus (GDM) remains uninvestigated. METHODS AND RESULTS: Pro-NT was quantified in 74 women with GDM, 74 healthy, gestational age-matched, pregnant controls, as well as in a second cohort comprising of 74 healthy, non-pregnant control women, using a chemiluminometric sandwich immunoassay. Pro-NT was correlated to measures of obesity, hypertension, glucose and lipid metabolism, renal function, and inflammation. Mean ± standard deviation of circulating Pro-NT levels were not significantly different in women with GDM (100.2 ± 75.7 pmol/l) as compared to healthy, pregnant controls (103.2 ± 37.4 pmol/l) and healthy, non-pregnant female controls (105.9 ± 38.9 pmol/l) (p = 0.661). Homeostasis model assessment of insulin resistance (HOMA-IR) and creatinine positively correlated with serum Pro-NT in multivariate regression analysis. In contrast, free fatty acids (FFA) were inversely correlated with circulating Pro-NT. Results sustained adjustment for pregnancy status. CONCLUSIONS: Circulating Pro-NT is not independently associated with GDM, but is with HOMA-IR, creatinine, and FFA even after adjustment for pregnancy status.

Association of metabolic parameters and rs726344 in FNDC5 with serum irisin concentrations.

BACKGROUND/OBJECTIVES: Irisin has been suggested as a novel myokine with beneficial effects in rodents. However, previous data in humans showed conflicting results regarding its association with metabolic phenotypes and regulation of secretion. Furthermore, although an association of rs726344 in FNDC5 (fibronectin type III domain containing 5) coding for irisin with insulin sensitivity was reported, the effects of genetic variation at this locus on irisin serum levels have not been investigated, so far. Therefore, we investigated circulating irisin and the associations with rs726344 in a cohort of >1000 subjects. SUBJECTS/METHODS: Irisin serum concentrations were measured with enzyme-linked immunosorbent assay. Associations with metabolic parameters including renal function, glucose and lipid metabolism, inflammation, as well as adipokine profiles, were assessed in regression models. Dynamic changes of serum irisin were investigated during oral glucose tolerance test (OGTT) in a subset of the cohort (n=136). rs726344 was genotyped in all subjects and analyzed for associations with serum irisin and traits of the metabolic syndrome. RESULTS: Irisin was negatively associated with fat mass, fasting glucose and dyslipidemia but not with other adipokines. Moreover, irisin decreased during an OGTT in a subcohort comprising subjects with normal glucose tolerance, impaired fasting glucose, impaired glucose tolerance and type 2 diabetes mellitus. rs726344 was not associated with serum irisin levels or with other anthropometric and biochemical parameters. CONCLUSIONS: Circulating irisin levels are associated with a beneficial metabolic profile but not with other adipokines and not with rs726344 in our cohort. Our data suggest a potential favorable role of irisin in the regulation of metabolism.

Cardiovascular magnetic resonance feature-tracking assessment of myocardial mechanics: Intervendor agreement and considerations regarding reproducibility.

AIM: To assess intervendor agreement of cardiovascular magnetic resonance feature tracking (CMR-FT) and to study the impact of repeated measures on reproducibility. MATERIALS AND METHODS: Ten healthy volunteers underwent cine imaging in short-axis orientation at rest and with dobutamine stimulation (10 and 20 µg/kg/min). All images were analysed three times using two types of software (TomTec, Unterschleissheim, Germany and Circle, cvi(42), Calgary, Canada) to assess global left ventricular circumferential (Ecc) and radial (Err) strains and torsion. Differences in intra- and interobserver variability within and between software types were assessed based on single and averaged measurements (two and three repetitions with subsequent averaging of results, respectively) as determined by Bland-Altman analysis, intraclass correlation coefficients (ICC), and coefficient of variation (CoV). RESULTS: Myocardial strains and torsion significantly increased on dobutamine stimulation with both types of software (p<0.05). Resting Ecc and torsion as well as Ecc values during dobutamine stimulation were lower measured with Circle (p<0.05). Intra- and interobserver variability between software types was lowest for Ecc (ICC 0.81 [0.63-0.91], 0.87 [0.72-0.94] and CoV 12.47% and 14.3%, respectively) irrespective of the number of analysis repetitions. Err and torsion showed higher variability that markedly improved for torsion with repeated analyses and to a lesser extent for Err. On an intravendor level TomTec showed better reproducibility for Ecc and torsion and Circle for Err. CONCLUSIONS: CMR-FT strain and torsion measurements are subject to considerable intervendor variability, which can be reduced using three analysis repetitions. For both vendors, Ecc qualifies as the most robust parameter with the best agreement, albeit lower Ecc values obtained using Circle, and warrants further investigation of incremental clinical merit.

Adipocyte fatty acid-binding protein is released from adipocytes by a non-conventional mechanism.

Adipocyte fatty acid-binding protein (AFABP) is an adipokine, which induces insulin resistance. However, AFABP does not possess any secretion-directed signals and the mechanisms for AFABP release have not been thoroughly assessed so far. In the current study, mechanisms for AFABP secretion were elucidated in 3T3-L1 adipocytes in vitro in the presence or absence of hormonal stimulation, calcium ionophore and secretion inhibitors by cell fractionation experiments, immunoblotting and ELISAs. We demonstrate that AFABP secretion is upregulated during adipocyte differentiation. AFABP secretion is not influenced by treatment with protein secretion inhibitors that block vesicular traffic at the endoplasmic reticulum and the Golgi apparatus. AFABP is secreted partially by adipocyte-derived microvesicles (ADMs), an established mechanism for unconventional secretion from adipocytes. Both total and ADM-secreted AFABP are downregulated by insulin and upregulated by the calcium ionophore ionomycin. Furthermore, murine RAW 264.7 macrophages secrete AFABP and AFABP release from these cells is upregulated by lipopolysaccharide treatment. Taken together, these results suggest that AFABP is actively released by unconventional mechanisms and by ADMs from 3T3-L1 adipocytes. Furthermore, AFABP secretion from fat cells is regulated by insulin and intracellular calcium.

Serum levels of fractalkine are associated with markers of insulin resistance in gestational diabetes.

AIMS: Fractalkine has recently been introduced as an adipokine that improves glucose tolerance. Regulation of fractalkine in gestational diabetes, as well as its association with markers of obesity, glucose and lipid metabolism, inflammation and renal function, has not been elucidated. METHODS: Circulating fractalkine was quantified by enzyme-linked immunosorbent assay in 74 women with gestational diabetes and 74 healthy, pregnant control subjects matched for age, BMI, and gestational age. RESULTS: Median (interquartile range) levels of fractalkine were not significantly different between the two groups [gestational diabetes: 2.24 (2.16) µg/l; control: 2.45 (1.38) µg/l] (P = 0.461). In multivariate linear regression analysis, fractalkine remained independently associated with homeostasis model assessment of insulin resistance (ß = -0.253, P = 0.002) and the proinflammatory adipokine progranulin (ß = 0.218, P = 0.007). CONCLUSIONS: Circulating fractalkine is not different between women with gestational diabetes and control subjects, but the adipokine is independently associated with markers of insulin resistance and proinflammatory progranulin in pregnancy.

Relationship between serum levels of angiopoietin-related growth factor and metabolic risk factors.

Angiopoietin-related growth factor (AGF, also known as angiopoietin-like protein 6) has been introduced as a novel hepatocyte-derived factor, which antagonizes obesity and insulin resistance in mice. However, human studies show conflicting results and are limited to a small cohort of patients. In the current study, we therefore sought to investigate AGF serum levels in a large metabolically well-characterized cohort. AGF serum concentrations were determined by commercial enzyme-linked immunosorbent assay in 697 patients of a cohort from Eastern Germany (Sorbs). Correlations of AGF serum levels with clinical and biochemical measures of glucose and lipid metabolism, as well as markers of renal function, were investigated. In nondiabetic subjects (n=627), AGF was positively correlated with markers of insulin resistance and negatively correlated with high-density lipoprotein cholesterol in univariate analyses (p<0.05). After adjustment for age, gender, and body mass index, none of these factors remained independently associated with AGF, neither in nondiabetic subjects nor in patients with type 2 diabetes mellitus (T2DM) (n=70). However, we confirmed existing data of significantly higher AGF concentrations in patients with T2DM as compared to controls in this large cohort. Circulating AGF is elevated in subjects with T2DM and related to the type of antidiabetic treatment, but is not independently associated with anthropometric parameters, indices of insulin sensitivity and secretion, or a number of other adipokines.

Different associations of adipokines in lean and healthy adults.

Regulation of adipokines in lean adults without metabolic disease and without eating disorders has not been comprehensively elucidated. We hypothesized that some of the established associations of these adipocyte-secreted proteins with anthropometric and biochemical measures of glucose homeostasis, lipid metabolism, renal function, as well as inflammation, differ in healthy and low weight adults as compared to overweight/obese patients. Eighty-one subjects with a body mass-index below 22.0 kg/m2 and without malnutrition or eating disorders, as well as fifty overweight/obese patients, were recruited for the study. Serum concentrations of seven adipokines (adiponectin, leptin, adipocyte fatty acid-binding protein [AFABP], chemerin, fibroblast growth factor [FGF]-21, resistin, retinol-binding protein [RBP]-4) were measured by enzyme-linked immunosorbent assays. Lean probands had significantly higher levels of adiponectin and resistin, as well as lower levels of leptin, AFABP, and RBP-4, as compared to overweight/obese subjects. Serum concentrations of adiponectin, leptin, AFABP, chemerin, and resistin were significantly higher in lean women as compared to men (p<0.05). In lean subjects, fasting insulin independently predicted leptin and resistin concentrations. Furthermore, C-reactive protein was independently associated with circulating AFABP and chemerin. Moreover, lean body mass was an independent predictor of leptin, fat mass predicted AFABP levels, whereas RBP-4 was independently correlated to age and triglycerides. In addition, high density lipoprotein cholesterol predicted AFABP. Our results support the notion that several of these adipokines are regulated in a different manner in lean adults as compared to overweight/obese subjects and patients with eating disorders.

Circulating adipocyte fatty acid binding protein is increased in chronic and acute renal dysfunction.

BACKGROUND AND AIMS: The adipokine adipocyte fatty acid binding protein (AFABP) is positively associated with the development of the metabolic syndrome, diabetes mellitus, and cardiovascular disease. We hypothesized that AFABP also increases with deteriorating renal function. METHODS AND RESULTS: Serum AFABP levels were quantified by enzyme linked immunosorbent assay in 532 patients with chronic kidney disease (CKD) covering the whole spectrum of estimated glomerular filtration rate (eGFR) categories from G1 to G5 (study population 1). Furthermore, AFABP was measured in 32 patients before and within 30 h after elective unilateral nephrectomy, a model of acute kidney dysfunction (AKD) (study population 2). Moreover, circulating AFABP was investigated in rats undergoing bilateral nephrectomy (BNE) as compared to sham-operated animals. Median serum AFABP levels adjusted for age, gender, and body mass index significantly increased with increasing eGFR category (G1: 22.0 µg/l; G2: 34.6 µg/l; G3: 56.7 µg/l; G4: 95.2 µg/l; and G5: 173.9 µg/l). Furthermore, renal dysfunction remained positively associated with AFABP in multivariate analysis in this cohort. In patients undergoing unilateral nephrectomy, AFABP increased significantly after surgery (42.1 µg/l) as compared to pre-surgical values (29.3 µg/l). Furthermore, relative changes of post-to-pre-surgical AFABP levels were independently associated with relative changes of post-to-pre-surgical creatinine concentrations. After BNE in rats, AFABP increased significantly as compared to sham-operated animals. CONCLUSIONS: We show that AFABP is significantly elevated in CKD and AKD patients. Furthermore, measures of renal function are associated with circulating AFABP. Moreover, animal experiments indicate that AFABP levels strongly depend on renal function.

Real-time phase-contrast flow MRI of haemodynamic changes in the ascending aorta and superior vena cava during Mueller manoeuvre.

AIM: To evaluate the potential of real-time phase-contrast flow magnetic resonance imaging (MRI) at 40 ms resolution for the simultaneous determination of blood flow in the ascending aorta (AA) and superior vena cava (SVC) in response to reduced intrathoracic pressure (Mueller manoeuvre). MATERIALS AND METHODS: Through-plane flow was assessed in 20 healthy young subjects using real-time phase-contrast MRI based on highly undersampled radial fast low-angle shot (FLASH) with image reconstruction by regularized non-linear inversion. Haemodynamic alterations (three repetitions per subject = 60 events) were evaluated during normal breathing (10 s), inhalation with nearly closed epiglottis (10 s), and recovery (20 s). RESULTS: Relative to normal breathing and despite interindividual differences, reduced intrathoracic pressure by at least 30 mmHg significantly decreased the initial peak mean velocity (averaged across the lumen) in the AA by -24 ± 9% and increased the velocity in the SVC by +28 ± 25% (p < 0.0001, n = 23 successful events). Respective changes in flow volume per heartbeat were -25 ± 9% in the AA and +49 ± 44% in the SVC (p < 0.0001, n = 23). Flow parameters returned to baseline during sustained pressure reduction, while the heart rate was elevated by 10% (p < 0.0001) after the start (n = 24) and end (n = 17) of the manoeuvre. CONCLUSIONS: Real-time flow MRI during low intrathoracic pressure non-invasively revealed quantitative haemodynamic adjustments in both the AA and SVC.

Adipocyte fatty acid binding protein: a novel adipokine involved in the pathogenesis of metabolic and vascular disease?

Adipocyte fatty acid binding protein (AFABP, also known as aP2 and FABP4) has recently been introduced as a novel fat-derived circulating protein. AFABP serum concentrations are positively correlated with markers of the metabolic syndrome and vascular disease in various cross-sectional and interventional studies. Furthermore, a small set of prospective studies indicates that high AFABP serum levels at baseline predict the risk for metabolic and vascular morbidity and mortality. Studies in Afabp (also known as Fabp4) knockout mice and AFABP inhibitor-treated animals suggest that total AFABP promotes insulin resistance, hypertriacylglycerolaemia and atherosclerosis by ligand/ligand delivery, as well as ligand-independent mechanisms. In contrast, the pathophysiological significance of circulating AFABP and the mechanisms leading to its release remain to be established. The current review summarises recent findings on the regulation and potential role of AFABP in metabolic and vascular disease.

Metabolic and genetic predictors of circulating adipocyte fatty acid-binding protein.

BACKGROUND: Adipocyte fatty acid-binding protein (AFABP) was recently introduced as a novel adipokine playing an important role in glucose homeostasis. In this study, we investigated the relationship between serum AFABP levels and metabolic, as well as cardiovascular parameters, in the self-contained population of Sorbs. Furthermore, we conducted a genome-wide association study on serum AFABP concentrations in the Sorbs and we separately analyzed the effects of two common variants in the FABP4 gene on AFABP serum concentration. METHODS: Serum AFABP concentrations were quantified by enzyme-linked immunosorbent assay and correlated with metabolic and cardiovascular parameters, as well as inflammatory markers and renal function, in 868 well-characterized non-diabetic Sorbs from Germany. RESULTS: Median AFABP serum concentrations were 1.5-fold higher in female subjects (23.03 µg l(-1)) as compared to male subjects (15.86 µg l(-1)). Waist-to-height ratio and glomerular filtration rate were independently associated with AFABP concentrations in multiple regression analysis in both female and male subjects. The genome-wide scan for association of single-nucleotide polymorphisms with serum AFABP levels in the Sorbs revealed 39 loci reaching P-values <10(-4). Two single-nucleotide polymorphisms, rs16909187 and rs10808846, representing common genetic variation in FABP4 did not show any effect on serum AFABP concentrations in our study cohort. CONCLUSION: AFABP serum concentrations are determined by parameters of fat distribution, renal function and gender.

Hereditary angioedema (HAE) in children and adolescents--a consensus on therapeutic strategies.

Hereditary angioedema due to C1 inhibitor (C1 esterase inhibitor) deficiency (types I and II HAE-C1-INH) is a rare disease that usually presents during childhood or adolescence with intermittent episodes of potentially life-threatening angioedema. Diagnosis as early as possible is important to avoid ineffective therapies and to properly treat swelling attacks. At a consensus meeting in June 2011, pediatricians and dermatologists from Germany, Austria, and Switzerland reviewed the currently available literature, including published international consensus recommendations for HAE therapy across all age groups. Published recommendations cannot be unconditionally adopted for pediatric patients in German-speaking countries given the current approval status of HAE drugs. This article provides an overview and discusses drugs available for HAE therapy, their approval status, and study results obtained in adult and pediatric patients. Recommendations for developing appropriate treatment strategies in the management of HAE in pediatric patients in German-speaking countries are provided.Conclusion Currently, plasma-derived C1 inhibitor concentrate is considered the best available option for the treatment of acute HAE-C1-INH attacks in pediatric patients in German-speaking countries, as well as for short-term and long-term prophylaxis.

Serum levels of the adipokine zinc-α2-glycoprotein are increased in preeclampsia.

BACKGROUND: Preeclampsia (PE) is associated with facets of the metabolic syndrome and an increased future metabolic and cardiovascular risk for mother and newborn. Recently, zinc-α2-glycoprotein (ZAG) has been proposed as a new adipokine involved in the pathogenesis of obesity. AIM: In the current study, we investigated ZAG serum levels in PE patients as compared to healthy gestational age-matched controls. SUBJECTS AND METHODS: We quantified serum concentrations of ZAG in patients with PE (no.=37) as compared to healthy gestational age-matched controls (no.=37) by enzyme-linked immunosorbent assay. Furthermore, association of this adipokine with renal function, glucose and lipid metabolism, as well as inflammation was studied. RESULTS: Median serum ZAG levels were 1.4-fold higher in PE patients (58.8 mg/l) as compared to controls (41.9 mg/l) (p<0.01). Furthermore, circulating ZAG was positively correlated to systolic and diastolic blood pressure, creatinine, triglycerides, and leptin in univariate analyses. In multiple regression analysis, creatinine remained independently associated with ZAG. CONCLUSIONS: We demonstrate that maternal ZAG serum concentrations are significantly increased in PE. Furthermore, renal function is an independent predictor of circulating ZAG.

Central vaspin administration acutely reduces food intake and has sustained blood glucose-lowering effects.

AIMS/HYPOTHESIS: Vaspin (visceral adipose tissue-derived serpin) was first identified as an adipokine in a rat model of type 2 diabetes, in which it is predominantly secreted from visceral adipose tissue. Serum concentrations of vaspin show a food intake-related diurnal variation. We therefore tested the hypothesis that vaspin plays a role in the regulation of food intake. METHODS: Vaspin levels in the hypothalamus and human stomach were determined by western blotting. The cerebrospinal fluid concentration of vaspin was measured in five healthy volunteers using an ELISA. Fed 11-week-old female db/db mice were given intraperitoneal injections of 1 mg/kg body weight of vaspin (n = 6) or saline (n = 6) on experimental days 1, 3 and 4. Changes in food intake and fed plasma glucose concentrations were determined after one intracerebroventricular administration of either 1 µg vaspin or artificial cerebrospinal fluid into 11-week-old female db/db (n = 8) and C57BL/6 mice (n = 8) up to 6 days after injection. RESULTS: We detected vaspin in the hypothalamus of db/db and C57BL/6 mice and in the cerebrospinal fluid of healthy individuals. Both peripheral and central vaspin administration decrease food intake in obese db/db and lean C57BL/6 mice. In db/db mice, vaspin treatment is associated with sustained glucose-lowering effects for at least 6 days after injection. In addition, we demonstrated expression of the gene encoding vaspin in the gastric mucosa in humans, and found that this was subject to regional variations. CONCLUSIONS/INTERPRETATION: Our data suggest a previously unrecognised role of vaspin in the regulation of food intake. We postulate that vaspin inhibits a protease that degrades an anti-orexigenic factor.

Serum levels of the adipokine fasting-induced adipose factor/angiopoietin-like protein 4 depend on renal function.

Fasting-induced adipose factor/angiopoietin-like protein 4 (FIAF/Angptl4) was recently introduced as a novel adipokine influencing glucose and lipid homeostasis. In the current study, we quantified circulating FIAF/Angtl4 levels in patients on chronic hemodialysis (CD) as compared to controls with a glomerular filtration rate above 50 ml/min. FIAF/Angptl4 was determined by ELISA in control (n=60) and CD (n=60) patients and correlated to clinical and biochemical measures of renal function, glucose and lipid metabolism, as well as inflammation, in both groups. Median serum FIAF/Angptl4 levels were more than 5-fold higher in CD patients (48.3 µg/l) as compared to control subjects (8.4 µg/l) (p<0.001). Furthermore, serum creatinine independently predicted FIAF/Angptl4 concentrations in multiple regression analyses in control subjects (p<0.01). In CD patients, C-reactive protein was independently and positively associated with circulating FIAF/Angptl4 (p<0.01). Taken together, we show that serum FIAF/Angptl4 levels are significantly increased in end-stage renal disease and independently associated with markers of renal function in control subjects.

[Lipodystrophy. Mechanisms, clinical presentation, therapy]. / Lipodystrophie. Mechanismen, Klinik, Therapie.

Lipodystrophy syndromes are a heterogenous group of congenital and acquired disorders with generalized or partial absence of subcutaneous adipose tissue. They are associated with severe metabolic abnormalities such as insulin resistance, diabetes mellitus, and hypertriglyceridemia that may result in life-threatening acute pancreatitis, steatohepatitis, and cardiovascular disease. Conventional lipid-lowering and antihyperglycemic medications may be insufficient to control severe metabolic abnormalities. The adipose tissue-derived hormone leptin has been investigated as a novel therapeutic option for severe lipodystrophy and significantly improves metabolic abnormalities in these patients. In Germany, leptin treatment for lipodystrophic patients with severe metabolic abnormalities is offered free of charge by the University Medicine Leipzig within a compassionate use program.

Fibroblast growth factor 19 serum levels: relation to renal function and metabolic parameters.

Fibroblast growth factor 19 (FGF19) was recently introduced as a novel metabolic regulator reversing diabetes mellitus, hepatic steatosis, hyperlipidemia, and adiposity. In the current study, we determined circulating FGF19 levels in patients on chronic hemodialysis (CD) as compared to controls with a glomerular filtration rate (GFR) above 50 ml/min. FGF19 was measured by ELISA in control (n=60) and CD (n=60) patients and correlated to clinical and biochemical measures of renal function, glucose, and lipid metabolism, as well as inflammation, in both groups. Median serum FGF19 levels were 1.5-fold higher in CD patients (266.7 microg/l) as compared to subjects with a GFR above 50 ml/min (178.1 microg/l) (p=0.001). Furthermore, fasting glucose negatively and independently predicted circulating FGF19 in controls (p<0.05). Moreover, adiponectin was a positive and C-reactive protein was a negative independent predictor of FGF19 serum concentrations in CD patients. Taken together, we have demonstrated that circulating FGF19 levels are significantly increased in end-stage renal disease. Furthermore, FGF19 is associated with a beneficial metabolic profile in both control and CD patients.

Serum levels of the adipokine lipocalin-2 are increased in preeclampsia.

BACKGROUND: Preeclampsia (PE) is a serious complication in pregnancy which increases the future risk for vascular and metabolic disease in both mother and newborn. Recently, lipocalin-2 has been introduced as a novel adipokine which contributes to obesity, insulin resistance, and vascular disease. AIM: In the current study, we investigated lipocalin-2 serum levels in PE patients as compared to healthy gestational age-matched controls. SUBJECTS AND METHODS: Lipocalin-2 serum concentrations were quantified by enzyme-linked immunosorbent assay in control (no.=22) and PE (no.=22) patients. Furthermore, lipocalin-2 levels were correlated to clinical and biochemical measures of renal function, glucose, and lipid metabolism, as well as inflammation. RESULTS: Median maternal lipocalin-2 concentrations were significantly increased in PE (121.3 µg/l) as compared to control subjects (99.8 µg/l) (p<0.05). Furthermore, circulating lipocalin 2 correlated positively with diastolic blood pressure, creatinine, and C reactive protein. In multivariate analyses, creatinine and C reactive protein remained independently associated with lipocalin-2 levels. CONCLUSIONS: We demonstrate that maternal lipocalin-2 concentrations are significantly increased in PE. Furthermore, markers of renal function and inflammation independently predict circulating lipocalin-2.

Therapeutic implications of the IL-21: IL-4 receptor system in children with common variable immunodeficiency syndrome.

OBJECTIVES: Interleukin-21 (IL-21) has been shown to restore immunoglobulin production together with Interleukin-4 (IL-4) in common variable immunodeficiency syndrome (CVID). Here, we elucidate the functional and structural properties of the corresponding IL-21R : IL-4R system. PATIENTS AND METHODS: An in vitro cell culture system was established to study the molecular effects of IL-21 and IL-4 on B cell differentiation, class-switch recombination (CSR) and immunoglobulin (Ig) production in 32 paediatric patients with CVID. MHC haplotypes and the IL21 and IL21R gene were analysed by genotyping. Ternary complexes of the IL-21 respectively IL-4 receptor were set-up by homology modeling and ligand-interaction was examined by molecular dynamics (MD) simulation. RESULTS: Stimulation with IL-21, IL-4 and CD40L uniformly induced IgG and IgA production in B cells from all tested patients by initiation of both CSR and AID-independent Ig production. No mutations were found in the coding regions of the IL21 or IL21R genes and no distinct HLA allele or extended haplotype could be correlated with the amount of Ig production or the gene expression pattern induced by IL-21. MD simulations of the modelled receptor complexes showed that IL-4 and IL-21 are both able to bind to IL-4R and IL-21R complexes in an interchangeable manner. CONCLUSIONS: The function of the IL-21R : IL-4R system seems not to be related to the aetiology of CVID in paediatric patients and might be suitable for a regenerative therapy.

Adipose triglyceride lipase gene expression in human visceral obesity.

In comparison to subcutaneous (SC) fat, visceral adipose tissue is more sensitive to catecholamine-induced lipolysis and less sensitive to the antilipolytic effects of insulin. Variation in the expression of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) have been reported. We therefore hypothesized that expression of adipose triglyceride lipase (ATGL) is different in visceral and SC depot and investigated whether ATGL mRNA expression is related to obesity, fat distribution and insulin sensitivity. ATGL, LPL, and HSL mRNA expression was measured in 85 paired samples of omental and subcutaneous adipose tissue in normal glucose tolerant lean and obese individuals. In addition, we included a subgroup of obese (BMI >30 kg/m2) individuals with either impaired or preserved insulin sensitivity determined by euglycemic-hyperinsulinemic clamps. ATGL mRNA levels are significantly decreased in insulin resistant obese subjects. Independently of body fat mass, omental ATGL mRNA correlates with fasting insulin concentration, glucose uptake during the steady state of the clamp and HSL mRNA expression. In obese, but not in lean subjects, LPL and HSL mRNA expression was significantly higher in omental compared to SC fat. In both depots, HSL mRNA was significantly lower in obese individuals. Visceral HSL mRNA expression is closely related to adipocyte size and fasting plasma insulin concentrations, whereas visceral fat area significantly predicts visceral LPL mRNA expression. ATGL mRNA expression is not significantly different between omental and SC fat. HSL, but not ATGL mRNA expression is closely related to individual and regional differences in adipocyte size. Impaired insulin sensitivity was associated with decreased ATGL and HSL mRNA expression, independently of body fat mass and fat distribution.