Matthias Laudes

Christian-Albrechts-Universität zu Kiel, Kiel, Schleswig-Holstein, Germany

Are you Matthias Laudes?

Claim your profile

Publications (41)133.09 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Psoriasis is associated with comorbidity including obesity, insulin resistance and diabetes mellitus type 2. In obesity the protein wnt5a is released from adipose tissue macrophages and was shown to be of importance in the development of insulin resistance. As wnt5a was also shown to be up-regulated in psoriatic skin lesions we investigated if wnt5a and its counterpart sFRP5 are altered in the circulation of lean and obese patients with psoriasis compared to lean and obese healthy volunteers by measuring serum concentrations of both proteins. Our results showed that wnt5a was significantly higher in lean patients with psoriasis (0.096 ng/ml; SD 0.12) compared to lean healthy controls (0.020 ng/ml; SD 0.04; p=<0.01) as well as in obese patients (0.177 ng/ml; SD 0.14) compared to obese healthy controls (0.011 ng/ml; SD 0.03; p=<0.001). Therefore, we suggest that in psoriasis an increase of wnt5a may contribute to the development of metabolic comorbidity. This article is protected by copyright. All rights reserved.
    Experimental Dermatology 04/2014; · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: lincRNAs recently have been discovered as evolutionary conserved transcripts of non-coding DNA sequences and have been implicated in the regulation of cellular differentiation. In humans, molecular studies have suggested a functional role for lincRNAs in cancer development. The aim of the present study was to examine whether these novel molecules are specifically regulated by different cytokines in cells of the innate immune system in humans in vivo and whether lincRNAs thereby might be involved in the pathophysiology of rheumatoid arthritis (RA). Therefore, CD14(+) monocytes were isolated from RA patients before and after anti-IL-6R (tocilizumab) or anti-TNF-α (adalimumab) therapy and lincRNA transcription was analysed by a microarray based experiment. As expected, we found lincRNAs to be present in CD14(+) monocytes of RA patients. However, of the total number of 7.419 lincRNAs examined in this study only a very small number was significantly regulated by either IL-6 or TNF-α (85 lincRNAs, corresponding to 1.1%). The numbers of lincRNAs regulated was higher due to TNF-α compared to IL-6. Interestingly, none of the identified lincRNAs was influenced by both, IL-6 and TNF-α, suggesting the regulation of lincRNA transcription to be highly specific for distinct cytokines. Taken together, our results suggest (1) that lincRNAs are novel intracellular molecular effectors of specific cytokines in cells of the innate immune system in humans in vivo and (2) that lincRNAs might be involved in the molecular pathophysiology of RA.
    Cytokine 04/2014; · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Inflammation and metabolism have been shown to be evolutionary linked and increasing evidence exists that pro-inflammatory factors are involved in the pathogenesis of obesity and type 2 diabetes. Until now, most data suggest that within adipose tissue these factors are secreted by cells of the innate immune system, e. g. macrophages. In the present study we demonstrate that B lymphocyte stimulator (BLyS) is increased in human obesity. In contrast to several pro-inflammatory factors, we found the source of BLyS in human adipose tissue to be the adipocytes rather than immune cells. In grade 3 obese human subjects, expression of BLyS in vivo in adipose tissue is significantly increased (p<0.001). Furthermore, BLyS serum levels are elevated in grade 3 human obesity (862.5+222.0 pg/ml vs. 543.7+60.7 pg/ml in lean controls, p<0.001) and are positively correlated to the BMI (r = 0.43, p<0.0002). In the present study, bariatric surgery significantly altered serum BLyS concentrations. In contrast, weight loss due to a very-low-calorie-formula-diet (800 kcal/d) had no such effect. To examine metabolic activity of BLyS, in a translational research approach, insulin sensitivity was measured in human subjects in vivo before and after treatment with the human recombinant anti-BLyS antibody belimumab. Since BLyS is known to promote B-cell proliferation and immunoglobulin secretion, the present data suggest that adipocytes of grade 3 obese human subjects are able to activate the adaptive immune system, suggesting that in metabolic inflammation in humans both, innate and adaptive immunity, are of pathophysiological relevance.
    PLoS ONE 01/2014; 9(4):e94282. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the present study was to examine to what extent different social network mechanisms are involved in the pathogenesis of obesity and insulin-resistance. We used nonparametric and parametric regression models to analyse whether individual BMI and HOMA-IR are determined by social network characteristics. A total of 677 probands (EGO) and 3033 social network partners (ALTER) were included in the study. Data gathered from the probands include anthropometric measures, HOMA-IR index, health attitudes, behavioural and socio-economic variables and social network data. We found significant treatment effects for ALTERs frequent dieting (p<0.001) and ALTERs health oriented nutritional attitudes (p<0.001) on EGO's BMI, establishing a significant indirect network effect also on EGO's insulin resistance. Most importantly, we also found significant direct social network effects on EGO's insulin resistance, evidenced by an effect of ALTERs frequent dieting (p = 0.033) and ALTERs sport activities (p = 0.041) to decrease EGO's HOMA-IR index independently of EGO's BMI. Social network phenomena appear not only to be relevant for the spread of obesity, but also for the spread of insulin resistance as the basis for type 2 diabetes. Attitudes and behaviour of peer groups influence EGO's health status not only via social mechanisms, but also via socio-biological mechanisms, i.e. higher brain areas might be influenced not only by biological signals from the own organism, but also by behaviour and knowledge from different human individuals. Our approach allows the identification of peer group influence controlling for potential homophily even when using cross-sectional observational data.
    PLoS ONE 01/2014; 9(4):e93860. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: lincRNAs recently have been discovered as evolutionary conserved transcripts of non-coding DNA sequences and have been implicated in the regulation of cellular differentiation. In humans, molecular studies have suggested a functional role for lincRNAs in cancer development. The aim of the present study was to examine whether these novel molecules are specifically regulated by different cytokines in cells of the innate immune system in humans in vivo and whether lincRNAs thereby might be involved in the pathophysiology of rheumatoid arthritis (RA). Therefore, CD14+ monocytes were isolated from RA patients before and after anti-IL-6R (tocilizumab) or anti-TNF-α (adalimumab) therapy and lincRNA transcription was analysed by a microarray based experiment. As expected, we found lincRNAs to be present in CD14+ monocytes of RA patients. However, of the total number of 7.419 lincRNAs examined in this study only a very small number was significantly regulated by either IL-6 or TNF-α (85 lincRNAs, corresponding to 1.1%). The numbers of lincRNAs regulated was higher due to TNF-α compared to IL-6. Interestingly, none of the identified lincRNAs was influenced by both, IL-6 and TNF-α, suggesting the regulation of lincRNA transcription to be highly specific for distinct cytokines. Taken together, our results suggest (1) that lincRNAs are novel intracellular molecular effectors of specific cytokines in cells of the innate immune system in humans in vivo and (2) that lincRNAs might be involved in the molecular pathophysiology of RA.
    Cytokine 01/2014; · 2.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The concentration of serum testosterone is mainly regulated by the testicular function, which is under control of the central hypothalamic-pituitary-gonadal axis. A certain amount of testosterone is converted into β-estradiol by adipose tissue. Obesity in men is often associated with decreased androgen levels. The aim of the present study was to examine the effect of caloric restriction on serum testosterone levels in obese men. Dietary intervention study was performed with a very low calorie diet (800 kcal/d) for 12 weeks. Thirteen obese human male subjects (median body mass index: 42.7 kg/m2) were included. Body composition was assessed by impedance analysis. Insulin sensitivity was estimated by leptin-to-adiponectin ratio (LAR). Testosterone (T), β-estradiol, albumin, sex hormone-binding globulin (SHBG), LH, and FSH serum concentrations were measured by enzyme immunoassays. Statistical analysis was performed on baseline and values after 3 months. Caloric restriction significantly increased total testosterone (6.97 nmol/l to 13.21 nmol/l; p=0.001) and SHBG (22.11 nmol/l to 42.12 nmol/l; p=0.001) concentrations in serum. This is caused by a significant improvement of the testicular function (LH/T: 0.36-0.20; p=0.005) and a significant reduction of the T/β-estradiol conversion rate (73.59-104.29; p=0.003). There was a significant negative correlation of improvement of testicular function and LAR (rs=-0.683 (p=0.042)). In obese men caloric restriction significantly increases the serum testosterone concentration. This is achieved by 2 distinct mechanisms, that is, improvement of testicular function and reduced conversion of testosterone to β-estradiol by aromatase activity of the adipose tissue.
    Hormone and Metabolic Research 11/2013; · 2.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVES: Blocking the interleukin-6 pathway by tocilizumab (TCZ) has been associated with changes in the lipoprotein profile, which could adversely impact cardiovascular (CV) risk in patients with rheumatoid arthritis (RA). In the present study, we addressed the effect of TCZ on lipoproteins in both fasting and non-fasting state in RA patients and tested the effect of TCZ on LDL receptor (LDLr) expression in vitro. METHODS: Twenty patients with active RA and an inadequate response to TNF blockers received monthly TCZ intravenously. On week 0, 1 and 6 blood was drawn before and after an oral fat load, the lipid profiles and HDL antioxidative capacity were measured. Effects of TCZ on LDLr expression in transfected HepG2 cells were subjected. RESULTS: After 6 weeks of TCZ, total cholesterol increased by 22% (4.8 ± 0.9 to 5.9 ± 1.3 mmol/L; p < 0.001), LDLc by 22% (3.0 ± 0.6 to 3.6 ± 0.8 mmol/L; p < 0.001) and HDLc by 17% (1.4 ± 0.4 to 1.7 ± 0.7 mmol/L; p < 0.016). Fasting triglycerides (TG) increased by 48% (1.0 ± 0.4 to 1.4 ± 0.8 mmol/L; p = 0.011), whereas postprandial incremental area under the curve TG increased by 62% (p = 0.002). Lipid changes were unrelated to the change in disease activity or inflammatory markers. No difference in HDL antioxidative capacity was found. In vitro, LDLr expression in cultured liver cells was significantly decreased following TCZ incubation (P < 0.001). CONCLUSIONS: TCZ adversely impacts on both LDLc as well as fasting and postprandial TG in patients with RA. The changes in hepatic LDLr expression following TCZ imply that adverse lipid changes may be a direct hepatic effect of TCZ. The net effect of TCZ on CV-morbidity has to be confirmed in future clinical trials.
    Atherosclerosis 05/2013; · 3.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Inflammatory mechanisms are involved in the pathogenesis of type 2 diabetes with interleukin (IL)-6 being particularly important. While long term exercise has been shown to be associated with reduction in IL-6 serum levels in several reports, the discussion on the effect of dietary intervention on IL-6 serum levels is controversial. In the present study, we aimed to investigate the effect of weight loss due to a very low calorie diet (VLCD) on insulin sensitivity and IL-6 serum levels in nondiabetic obese human individuals. 10 patients with obesity were examined during 12 weeks of a VLCD (800 kcal/d). Body composition was measured by impedance analysis. Blood samples were taken before, during, and after the dietary intervention. Leptin, adiponectin, and IL-6 serum levels were measured by ELISA. The body weight decreased significantly from 123.9±6.2-103.5±5.6 kg with a significant reduction in body fat content (43.2±2.3-36.1±3.1%). Leptin levels exhibited a significant decrease from 56.8±5.6-27.9±5.6 ng/ml while adiponectin levels increased significantly from 7.5±0.9-10.6±1.1 μg/ml. Thereby the leptin-to-adiponectin ratio, a novel marker for insulin sensitivity, significantly improved. Mean IL-6 serum concentrations were within the normal range (3.2±0.8 pg/ml) before the study and were not significantly altered by the nutritional therapy. Despite improvement of insulin sensitivity, IL-6 serum levels did not change throughout the study period, suggesting that in nondiabetic obese human subjects IL-6 might have only a minor role in the impairment of insulin sensitivity.
    Hormone and Metabolic Research 03/2012; 44(6):465-70. · 2.15 Impact Factor
  • Cell metabolism 03/2012; 15(3):265-6; author reply 267-9. · 17.35 Impact Factor
  • Clinical Endocrinology 01/2012; 77(2):332-4. · 3.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hyperglycemia is commonly observed in extremely low gestational age newborns (ELGANs) and is associated with both increased morbidity and mortality. The objective of this study was to examine the relationship between neonatal hyperglycemia and adiponectin levels in ELGANs. Ten preterm infants between 22+6/7 and 27+3/7 weeks' gestation with neonatal hyperglycemia (defined as pre-feeding blood glucose levels above 200mg/dl on two consecutive measurements with a maximum parenteral glucose infusion of 4 mg/kg*min(-1)) formed the case cohort of this study. To every single patient of this case cohort a patient with normal fasting ( = pre-feeding) blood glucose levels was matched in terms of gestational age and gender. Adiponectin ELISAs were performed both at onset of hyperglycemia and at term-equivalent age. In the case cohort 9/10 patients had to be treated with insulin for 1-26 days (range 0.01-0.4 IU/kg*h(-1)). Compared to matched-paired controls, significant hypoadiponectinemia was observed at onset of hyperglycemia in these affected patients (6.9 µg/ml versus 15.1 µg/ml, p = 0.009). At term equivalent age, normoglycemia without any insulin treatment was found in both groups. Moreover, adiponectin levels at that time were no longer significantly different (12.3 µg/ml versus 20.0 µg/ml; p = 0.051) possibly indicating a mechanistic relevance of this adipokine in regulating insulin sensitivity in ELGANs. Decreased circulating adiponectin levels are correlated with hyperglycemia in ELGANs and may contribute to the pathogenesis of impaired glucose homeostasis in these infants. These findings suggest that adiponectin might be a potential future drug target for the potentially save treatment of hyperglycemia in pre-term infants.
    PLoS ONE 01/2012; 7(6):e38481. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Obesity is associated with macrophage infiltration of adipose tissue. These inflammatory cells affect adipocytes not only by classical cytokines but also by the secreted glycopeptide wnt5a. Healthy adipocytes are able to release the wnt5a inhibitor sFRP5. This protective effect, however, was found to be diminished in obesity. The aim of the present study was to examine (1) whether obese human subjects exhibit increased serum concentrations of wnt5a and (2) whether wnt5a and/or sFRP5 serum concentrations in obese subjects can be influenced by caloric restriction. 23 obese human subjects (BMI 44.1 ± 1.1 kg/m(2)) and 12 age- and sex-matched lean controls (BMI 22.3 ± 0.4 kg/m(2)) were included in the study. Obese subjects were treated with a very low-calorie diet (approximately 800 kcal/d) for 12 weeks. Body composition was assessed by impedance analysis, insulin sensitivity was estimated by HOMA-IR and the leptin-to-adiponectin ratio and wnt5a and sFRP5 serum concentrations were measured by ELISA. sFRP5 expression in human adipose tissue biopsies was further determined on protein level by immunohistology. Pro-inflammatory wnt5a was not measurable in any serum sample of lean control subjects. In patients with obesity, however, wnt5a became significantly detectable consistent with low grade inflammation in such subjects. Caloric restriction resulted in a weight loss from 131.9 ± 4.0 to 112.3 ± 3.2 kg in the obese patients group. This was accompanied by a significant decrease of HOMA-IR and leptin-to-adiponectin ratio, indicating improved insulin sensitivity. Interestingly, these metabolic improvements were associated with a significant increase in serum concentrations of the anti-inflammatory factor and wnt5a-inhibitor sFRP5. Obesity is associated with elevated serum levels of pro-inflammatory wnt5a in humans. Furthermore, caloric restriction beneficially affects serum concentrations of anti-inflammatory sFRP5 in such subjects. These findings suggest a novel regulatory system in low grade inflammation in obesity, which can be influenced by nutritional therapy.
    PLoS ONE 01/2012; 7(2):e32437. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In patients with obesity and type 2 diabetes, adipose tissue is infiltrated by macrophages known to alter adipogenesis of mesenchymal precursor cells via secretion of proinflammatory cytokines. Recently, it has been shown that under certain conditions, immune cells can also express wnt-5a, a factor known to inhibit adipogenesis in humans. Therefore, in this study we aimed to investigate whether macrophages affect adipogenesis of mesenchymal precursor cells via wnt-5a. Wnt-5a was found to be expressed in adipose tissue macrophages in obese and type 2 diabetic human subjects in vivo by immunohistochemistry of adipose tissue biopsies. Furthermore, wnt-5a was detectable in circulating CD14(+) blood monocytes of human subjects with obesity and type 2 diabetes on RNA level by real-time PCR. Besides expression analysis in vivo, we also performed functional studies to explore the role of wnt-5a in low-grade inflammation of adipose tissue. In a cell culture experiment, macrophage-conditioned differentiation medium inhibited adipogenesis of 3T3-L1 cells. This inhibitory effect was restored by adding neutralising anti-wnt-5a antibodies. In conclusion, our data indicate that macrophages alter adipogenesis of 3T3-L1 cells not only via classical proinflammatory cytokines, but also via wnt signalling molecules.
    International journal of obesity (2005) 02/2011; 35(11):1450-4. · 5.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Lipoprotein(a) [Lp(a)] is an independent risk factor for cardiovascular disease. The interleukin-6 (IL-6) receptor antagonist tocilizumab has been shown to lower serum Lp(a) concentrations. We investigated whether the IL-6 single nucleotide polymorphism -174G/C is associated with baseline serum Lp(a) concentrations. We divided 2321 subjects from the Lipid Analytic Cologne (LIANCO) cohort into 2 groups, the ones with substantially elevated Lp(a), defined as concentrations ≥60 mg/dl (n = 510), and the ones with Lp(a) <60 mg/dl (n = 1811). The association with the genotypes GG (33.7%), GC (50.75%) and CC (15.55%) was investigated. The GC and the CC genotype were associated with a significantly increased odds ratio of having substantially elevated Lp(a) concentrations (OR = 1.3, 95% CI 1.04 to 1.63, P = 0.02 and OR = 1.44, 95% CI 1.06 to 1.93, P = 0.018). These associations remained significant after adjusting for age, sex, smoking behavior, body mass index, serum lipoproteins, hypertension and diabetes. Of these covariates, only LDL cholesterol was significantly and independently associated with elevated Lp(a) concentrations. The IL-6 single nucleotide polymorphism -174G/C is associated with increased odds of having elevated Lp(a). Whether this association plays a role in the Lp(a)-lowering effects of IL-6 receptor antagonists remains to be established.
    PLoS ONE 01/2011; 6(9):e24719. · 3.53 Impact Factor
  • Matthias Laudes
    [Show abstract] [Hide abstract]
    ABSTRACT: The development of obesity is characterised not only by increased storage of lipids in existing fat cells but also by the generation of new adipocytes from progenitor cells. This process, called adipogenesis, can be divided into two related steps. First, during determination, multipotent mesenchymal stem cells commit to preadipocytes. These cells exhibit similar morphology compared with stem cells; however, they are committed to the adipogenic lineage and are not longer able to transform into osteoblasts, myocytes or chondrocytes. Secondly, during differentiation, preadipocytes become mature fat cells. As in other developmental processes, adipogenesis is tightly regulated at a molecular level by several transcription factors. Within the last decade, it has also become clear how the activity of these transcription factors is coordinated by extracellular signals. In this respect, secreted WNT signalling molecules are particularly important. Several members of the WNT family have been shown to inhibit early steps of adipogenesis. Conversely, endogenous inhibitors of WNT signalling were found to promote generation of adipocytes, indicating a fundamental role of these bioactive peptides in adipogenesis. From a pathophysiological point of view, it is of interest that polymorphisms in genes of the WNT signalling system have been associated with the development of obesity and type 2 diabetes in humans. Moreover, recent findings indicate that certain WNT molecules are involved in the so-called low-grade inflammation of adipose tissue, which is crucial in the development of obesity-associated insulin resistance. These important findings in nutritional and metabolic medicine will be summarised in the present review.
    Journal of Molecular Endocrinology 01/2011; 46(2):R65-72. · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Wnt/β-catenin signaling network offers potential targets to diagnose and uncouple obesity from its metabolic complications. In this study, we investigate the role of the Wnt antagonist, secreted frizzled-related protein 1 (SFRP1), in promoting adipogenesis in vitro and adipose tissue expansion in vivo. We use a combination of human and murine, in vivo and in vitro models of adipogenesis, adipose tissue expansion and obesity-related metabolic syndrome to profile the involvement of SFRP1. SFRP1 is expressed in both murine and human mature adipocytes. The expression of SFRP1 is induced during in vitro adipogenesis, and SFRP1 is preferentially expressed in mature adipocytes in human adipose tissue. Constitutive ectopic expression of SFRP1 is proadipogenic and inhibits the Wnt/β-catenin signaling pathway. In vivo endogenous levels of adipose SFRP1 are regulated in line with proadipogenic states. However, in longitudinal studies of high-fat-diet-fed mice, we observed a dynamic temporal but biphasic regulation of endogenous SFRP1. In agreement with this profile, we observed that SFRP1 expression in human tissues peaks in patients with mild obesity and gradually falls in morbidly obese subjects. Our results suggest that SFRP1 is an endogenous modulator of Wnt/β-catenin signaling and participates in the paracrine regulation of human adipogenesis. The reduced adipose expression of SFRP1 in morbid obesity and its knock-on effect to prevent further adipose tissue expansion may contribute to the development of metabolic complications in these individuals.
    International journal of obesity (2005) 12/2010; 34(12):1695-705. · 5.22 Impact Factor
  • Clinical Research in Cardiology 12/2010; 100(4):379-82. · 3.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Low-grade inflammation is important in the development of obesity related pathologies such as insulin resistance and type 2 diabetes, and also cardiovascular disease. Visfatin/PBEF/Nampt and resistin are proinflammatory adipokines secreted from adipocytes, monocytes, and macrophages, and have been linked to atherosclerotic plaque formation, recently. The aim of the present study was to investigate if the expression of these molecules in circulating blood monocytes is altered in obese and/or type 2 diabetic human subjects. Monocytes were isolated by CD14-antibody based magnetic cell sorting from blood samples of 17 lean controls, 20 obese nondiabetic subjects, and 19 obese patients with type 2 diabetes. FACS analysis was performed to test purity of the cell preparations. Expression of the different adipokines was measured by multiplex real-time PCR on RNA-level. Visfatin/PBEF/Nampt was found to be very strongly expressed in monocytes, whereas resistin levels were significantly lower. Furthermore, visfatin/PBEF/Nampt expression was significantly upregulated in obese type 2 diabetic patients, whereas obese nondiabetics exhibited similar levels compared to lean controls, indicating that visfatin/PBEF/Nampt levels are related to type 2 diabetes rather than to obesity. In contrast, resistin expression displayed a different pattern being significantly increased in obese subjects compared to controls but not related to type 2 diabetes. These data suggest a differential role for these two proinflammatory adipokines in linking metabolic diseases to atherosclerosis with visfatin/PBEF/Nampt being more important in patients with type 2 diabetes and resistin in obese but nondiabetic human subjects.
    Hormone and Metabolic Research 04/2010; 42(4):268-73. · 2.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Dipeptidyl-peptidase (DPP)-4, which catalizes the degradation of the insulinotropic incretin glucagon-like-peptide (GLP)-1, and the DPP-4 like enzyme attractin are involved in activation of T-lymphocytes and monocytes. Recently, it has been demonstrated, that the risk for certain infections is increased in type 2 diabetic patients under DPP-4 inhibitor treatment. The aim of the present study was to examine the expression of DPP-4 and attractin in circulating blood monocytes of obese and type 2 diabetic subjects. Monocytes were isolated by CD14-antibody based magnetic cell sorting from blood samples of 17 lean controls, 20 obese, non-diabetic subjects and 19 obese patients with type 2 diabetes. FACS analysis was performed to test purity of the cell preparations. Expression was measured by multiplex RT-PCR on RNA-level. DPP-4 and attractin were detectable in human circulating monocytes with attractin being expressed at higher levels compared to DPP-4. Both enzymes were significantly higher expressed in circulating blood monocytes of obese subjects compared to lean controls. In contrast, type 2 diabetes did not significantly affect expression levels. Finally, neither DPP-4 nor attractin expression was altered by sitagliptin or insulin treatment. In conclusion, our data demonstrate, that expressions of DPP-4 and attractin in circulating blood monocytes of human subjects are influenced by metabolic abnormalities with obesity being an important factor.
    Experimental and Clinical Endocrinology & Diabetes 03/2010; 118(8):473-7. · 1.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Increasing adipocyte size as well as numbers is important in the development of obesity and type 2 diabetes, with adipocytes being generated from mesenchymal precursor cells. This process includes the determination of mesenchymal stem cells (MSC) into preadipocytes (PA) and the differentiation of PA into mature fat cells. Although the process of differentiation has been highly investigated, the determination in humans is poorly understood. In this study, we compared human MSC and human committed PA on a cellular and molecular level to gain further insights into the regulatory mechanisms in the determination process. Both cell types showed similar morphology and expression patterns of common mesenchymal and hematopoietic surface markers. However, although MSC were able to differentiate into adipocytes and osteocytes, PA were only able to undergo adipogenesis, indicating that PA lost their multipotency during determination. WNT-5a expression showed significantly higher levels in MSC compared with PA suggesting that WNT-5a down-regulation might be important in the determination process. Indeed, incubation of human MSC in medium containing neutralizing WNT-5a antibodies abolished their ability to undergo osteogenesis, although adipogenesis was still possible. An opposite effect was achieved using recombinant WNT-5a protein. On a molecular level, WNT-5a was found to promote c-Jun N-terminal kinase-dependent intracellular signaling in MSC. Activation of this noncanonical pathway resulted in the induction of osteopontin expression further indicating pro-osteogenic effects of WNT-5a. Our data suggest that WNT-5a is necessary to maintain osteogenic potential of MSC and that inhibition of WNT-5a signaling therefore plays a role in their determination into PA in humans.
    Journal of Biological Chemistry 02/2010; 285(9):6170-8. · 4.65 Impact Factor

Publication Stats

501 Citations
133.09 Total Impact Points

Institutions

  • 2013–2014
    • Christian-Albrechts-Universität zu Kiel
      • Institute of Experimental Medicine
      Kiel, Schleswig-Holstein, Germany
  • 2012–2014
    • University Medical Center Schleswig-Holstein
      Kiel, Schleswig-Holstein, Germany
  • 2009–2012
    • University of Cologne
      • • Department of Internal Medicine
      • • Center for Molecular Medicine (CMMC)
      Köln, North Rhine-Westphalia, Germany
  • 2004–2010
    • University of Cambridge
      • Department of Clinical Biochemistry
      Cambridge, ENG, United Kingdom