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CAMP (Cathelicidin antimicrobial peptide) is synthesized and secreted by adipocytes and involved in adipose tissue (AT) innate immune response and host defense of subcutaneous AT against Gram positive bacteria. Data on the regulation of CAMP in obesity and during weight loss are scarce and reference values do not exist. Serum CAMP levels (ELISA) and AT gene expression levels (quantitative real time PCR) were investigated in two large and longitudinal (12 months) cohorts of severely obese patients undergoing either a low calorie diet (LCD; n=79) or bariatric surgery (BS; n=156). The impact of metabolic factors on CAMP expression in vitro was investigated in differentiated 3T3-L1 adipocytes. CAMP serum levels significantly increased after BS but not during LCD. Females had lower CAMP serum levels and lower gene expression levels in subcutaneous AT. CAMP was positively correlated to unfavorable metabolic factors/adipokines and negatively to favorable factors/adipokines. CAMP gene expression was higher in subcutaneous than in visceral AT but serum CAMP levels were not correlated to levels of AT gene expression. While certain bile acids upregulated CAMP expression in vitro, high glucose/insulin as well as GLP-1 had an inhibitory effect. There exist gender-specific and AT compartment-specific effects on the regulation of CAMP gene expression. Weight loss induced by BS (but not by LCD) upregulated CAMP serum levels suggesting the involvement of weight loss-independent mechanisms in CAMP regulation such as bile acids, incretins and metabolic factors. CAMP might represent an adipokine at the interface between metabolism and innate immune response. [ABSTRACT FROM AUTHOR]

The postprandial regulation of lipocalin-2 and retinol binding protein 4 (RBP-4) by oral uptake of lipids and carbohydrates in healthy ndividuals has not yet been investigated. The regulation of lipocalin-2 and RBP-4 in 2 large cohorts of healthy volunteers during oral lipid tolerance test (OLTT; n = 100) and oral glucose tolerance test (OGTT; n = 100) was analyzed. One hundred healthy volunteers underwent OLTT and OGTT in an outpatient setting. Venous blood was drawn after 0, 2, 4, and 6 h in OLTT and after 0, 1, and 2 h in OGTT. In order to dissect carbohydrateinduced from lipid induced effects, a novel OLTT solution completely free of carbohydrates and protein was applied. Subjects were characterized by anthropometric and laboratory parameters. Serum concentrations of lipocalin-2 and RBP-4 were measured by enzyme-linked immunosorbent assay (ELISA). Whereas RBP-4 levels remained unchanged during OGTT, lipocalin-2 concentrations significantly decreased during OGTT. During OLTT, RBP-4 levels were not influenced, whereas lipocalin-2 levels decreased significantly and stepwise. Fasting concentrations of RBP-4 were negatively correlated with BMI and waist-hip ratio, whereas lipocalin-2 levels were positively associated with BMI and waist-hip ratio. Female users of hormonal contraception had higher RBP-4 levels than females not on contraceptives. There is no significant short-term regulation of RBP-4 by orally ingested lipids or carbohydrates. Lipocalin-2 is downregulated after lipid and carbohydrate ingestion and this kind of regulation was not predicted by age, sex, triglycerides, glucose, or insulin levels. [ABSTRACT FROM AUTHOR]

Background and aim: Dysbalance of pro- and anti-inflammatory adipokines is a hallmark of metabolic syndrome but their nutrition-dependent regulation in healthy individuals is poorly characterized. We investigated pro-inflammatory resistin and anti-inflammatory adiponectin regulation during oral lipid ingestion (OLI) in healthy adults. Response of resistin upon free fatty acid (FFA) stimulation was investigated in 3T3-L1 adipocytes. Material and methods: 100 healthy volunteers underwent OLI. Venous blood was drawn after 0, 2, 4, and 6 hours (h). Subjects were characterized by anthropometric and standard laboratory parameters. Serum concentrations of adiponectin and resistin were measured by enzymelinked immunosorbent assay (ELISA). Adipocytes were stimulated with FFA and concentrations of adipokines were measured by ELISA. Results: Irrespective of BMI and gender, OLI led to a significant reduction of resistin serum levels in a stepwise manner whereas adiponectin concentrations remained unchanged. There were positive correlations of resistin with waist/hip ratio and visfatin levels, as was calculated by regression analysis. Resistin concentrations were significantly higher in smokers when compared to non-smokers. Adiponectin concentrations were higher in females and in users of hormonal contraception. Adiponectin levels showed a positive correlation with heart rate and HDL cholesterol and a negative correlation with age, waist/hip-ratio, BMI, diastolic/systolic blood pressure, visfatin levels and LDL/HDL-ratio. Resistin secretion was significantly induced by palmitic acid, linoleic acid and oleic acid in adipocytes. Conclusions: OLI is a physiological repressor of systemic resistin release whereas FFA upregulate resistin release in vitro from adipocytes. [ABSTRACT FROM AUTHOR]

Background: Studies postulate an involvement of adipokines in inflammatory gastrointestinal diseases. Leptin-deficient ob/ob mice as well as TLR9-deficient mice have a more moderate course of chronic DSS-induced colitis (DSS-CC) and adipocytes do express functional TLR9 molecules. Material and Methods: Adipokine mRNA expression in visceral adipose tissue of mice before and after the induction of DSS-CC was investigated. Experiments were performed in both TLR9wt/wt and TLR9-/- mice. In vitro, the effect of TLR9 blocking peptide on leptin and visfatin protein secretion was studied in 3T3-L1 adipocytes. Results: Induction of DSS-CC led to an upregulation of leptin mRNA expression in TLR9wt/wt mice, while TLR9-/- animals showed a significant reduction of leptin expression even below baseline. While visfatin expression remained unchanged in TLR9wt/wt animals, TLR9-/- mice exhibited a significant induction during DSSCC. CTRP-3 expression was reduced after colitis induction only in TLR9-/- animals. Of note, IL-6 expression levels remained unchanged, while CXCL1/KC and cyclophilin A expression was reduced in DSS-CC. Inhibition of TLR9 signaling by using TLR9 blocking peptide led to reduced leptin protein secretion into cell culture supernatants in 3T3-L1 adipocytes, while visfatin protein secretion was enhanced. Conclusions: DSS-CC leads to differential adipokine expression profiles in the visceral fat pad in TLR9wt/wt vs. TLR9-/- mice. In vitro, inhibition of TLR9 signaling induces visfatin secretion while inhibiting leptin secretion in adipocytes. Thus, visceral adipokines are regulated by intact TLR9 signaling pathway and a specific interplay between the leptin- and the TLR9-pathways might be of pathophysiological importance in chronic intestinal inflammation. [ABSTRACT FROM AUTHOR]

Context: Regulation of FGF-19 and FGF-21 by oral uptake of lipids and carbohydrates in healthy individuals is poorly characterized. Objective: We investigated the regulation of FGF-19 and FGF-21 in 2 large cohorts of healthy volunteers during oral lipid tolerance test (OLTT; n = 100) and oral glucose tolerance test (OGTT; n = 100). Design and setting: 100 volunteers underwent OLTT and OGTT in an outpatient setting. Venous blood was drawn at 0 h (fasting) and at 2, 4, and 6 h in OLTT or 1 and 2 h in OGTT. In order to dissect carbohydrate-induced from lipid-induced effects, a special OLTT solution was applied. Subjects were characterized by anthropometric and laboratory parameters. Serum concentrations of FGF-19 and FGF-21 were measured by enzymelinked immunosorbent assay (ELISA). Results: Mean FGF-19 levels ranged between 12 and 544 pg/ml with a fasting mean value of 105 ± 81 pg/ml and 118 ± 86 pg/ml in OLTT and OGTT. Mean FGF-21 levels ranged between 4 and 1 393 pg/ml with a fasting mean value of 160 ± 204 pg/ml and 235 ± 288 pg/ml in OLTT and OGTT. There was a significant, positive correlation between FGF-19 and FGF-21 in OLTT (p < 0.001, r = 0.5) and in OGTT (p = 0.011, r = 0.4). FGF-21 levels were positively correlated with waist circumference and waist hip-ratio in both cohorts. OGTT had no effect on FGF-19 and FGF- 21. In contrast, FGF-19 levels were significantly induced and FGF-21 levels were significantly reduced during OLTT. Conclusions: OLTT is a physiological inductor of FGF-19 and a repressor of FGF-21 in healthy adults. There is a significant and positive correlation between FGF-19 and FGF-21. Dietary lipids specifically and differentially regulate FGF-19 and FGF-21 whereas dietary carbohydrates have no effect. The present data provide the clinical basis for the postulated negative feedback loop between dietary lipids and postprandial inhibition of hepatic lipogenesis. [ABSTRACT FROM AUTHOR]

Background and aim: The C1q/TNF-related protein (CTRP) family represents a growing family of adiponectin paralogous proteins. CTRP-5 was detected in adipose tissue of mice and plays a role in the context of the metabolic syndrome. It was the aim to investigate the detailed expression profile of CTRP-5 in a variety of adipocytic cells and to determine whether CTRP-5 circulates in human serum. Moreover, regulation and function of CTRP-5 was studied in the context of adi-pocyte biology. Material and methods: CTRP-5 serum levels were measured in 50 healthy subjects by ELISA. Genotype analysis was performed by direct sequencing in 200 probands. CTRP-5 mRNA and protein expression was analyzed by RT-PCR, realtime RT-PCR and Western blot. Recombinant CTRP-5 and fatty acids were used for stimulation experiments in 3T3-L1 adipocytes. siRNA-mediated knockdown of CTRP-3 was performed during adipocyte differentiation. Results: CTRP-5 mRNA and protein was strongly expressed in a wide variety of human and murine adipocytic cells and was induced during adipocyte differentiation. Saturated fatty acids increased CTRP-5 expression in adipocytes. siRNA-mediated cellular knockdown of CTRP-3 in adipocytes resulted in an upregulation of CTRP-5 expression. CTRP-5 inhibited the release of resistin and adiponectin dose-dependently. CTRP-5 circulates abundantly in human sera with a broad interindividual variation. The SNP 1014 T/A was not associated with type 2 diabetes mellitus in 200 Caucasian probands. Conclusions: CTRP-5 might be a novel adipok-ine that circulates abundantly in human sera. CTRP-5 is functionally involved in adipocyte biology and there might exist a counter-regulatory connection with its family member, CTRP-3. [ABSTRACT FROM AUTHOR]

Background: The growing family of C1Q/TNFrelated proteins is characterized by structural homologies to the anti-inflammatory adipokine adiponectin. CTRP-3 was recently reported to function as an anti-infl ammatory LPS-antagonist in vitro . Material and methods: Human subcutaneous and visceral adipocytes and murine 3T3-L1 adipocytes were used for analysis of CTRP-3 expression and function. Western blot analysis of CTRP-3, siRNA mediated knockdown of CTRP-3, Oil red O staining, assessment of basal and epinephrine- induced lipolysis, ELISA-based measurements of supernatant chemokines, recombinant CTRP-3 protein expression, and Staphylococcus aureus (S. aureus) infection assays were used. Results: CTRP-3 is expressed in subcutaneous and visceral adipocytes. CTRP-3 is positively regulated by insulin, whereas chronic LPS-exposure inhibits terminal adipocyte differentiation and CTRP-3 expression. Intracellular infection of adipocytes by S. aureus also decreases CTRP-3 expression. As demonstrated by siRNA-mediated cellular knockdown of CTRP-3 in adipocytes, CTRP-3 regulates resistin secretion and lipolysis. Conclusion: CTRP-3 is expressed in human adipocytes and plays an important role in adipocyte physiology such as lipolysis and adipokine secretion. Both, metabolic factors and infection/ inflammation-related factors regulate CTRP-3 expression. [ABSTRACT FROM AUTHOR]