Nadine Schlichting

Combined Proteomic and Metabolomic Profiling of Serum Reveals Association of the Complement System with Obesity and Identifies Novel Markers of Body Fat Mass Changes

Obesity is associated with multiple adverse health effects and a high risk of developing metabolic and cardiovascular diseases. Therefore, there is a great need to identify circulating parameters that link changes in body fat mass with obesity. This study combines proteomic and metabolomic approaches to identify circulating molecules that discriminate healthy lean from healthy obese individuals in an exploratory study design. To correct for variations in physical activity, study participants performed a one hour exercise bout to exhaustion. Subsequently, circulating factors differing between lean and obese individuals, independent of physical activity, were identified. The DIGE approach yielded 126 differentially abundant spots representing 39 unique proteins. Differential abundance of proteins was confirmed by ELISA for antithrombin-III, clusterin, complement C3 and complement C3b, pigment epithelium-derived factor (PEDF), retinol binding protein 4 (RBP4), serum amyloid P (SAP), and vitamin-D binding protein (VDBP). Targeted serum metabolomics of 163 metabolites identified 12 metabolites significantly related to obesity. Among those, glycine (GLY), glutamine (GLN), and glycero-phosphatidylcholine 42:0 (PCaa 42:0) serum concentrations were higher, whereas PCaa 32:0, PCaa 32:1, and PCaa 40:5 were decreased in obese compared to lean individuals. The integrated bioinformatic evaluation of proteome and metabolome data yielded an improved group separation score of 2.65 in contrast to 2.02 and 2.16 for the single-type use of proteomic or metabolomics data, respectively. The identified circulating parameters were further investigated in an extended set of 30 volunteers and in the context of two intervention studies. Those included 14 obese patients who had undergone sleeve gastrectomy and 12 patients on a hypocaloric diet. For determining the long-term adaptation process the samples were taken six months after the treatment. In multivariate regression analyses, SAP, CLU, RBP4, PEDF, GLN, and C18:2 showed the strongest correlation to changes in body fat mass. The combined serum proteomic and metabolomic profiling reveals a link between the complement system and obesity and identifies both novel (C3b, CLU, VDBP, and all metabolites) and confirms previously discovered markers (PEDF, RBP4, C3, ATIII, and SAP) of body fat mass changes.

Metaproteome Analysis and Molecular Genetics of Rat Intestinal Microbiota Reveals Section and Localization Resolved Species Distribution and Enzymatic Functionalities

The digestion of food ingredients depends on the action of the gut microbiota and has a significant influence on the health, especially in the case of metabolic diseases, of the host organism. Despite the relevance of the structure and functionalities in the microbiota for the metabolism of the host, the spatial resolution of microbial consortia and the functionalities in the different gut sections of the rat are mostly unknown. Since there are suitable rat models for human metabolic diseases, the microbiota of the rat is of special interest. Samples along the intestinal tract of rats were investigated using metaproteomics and 16S rRNA gene pyrosequencing. The procedures for harvesting bacteria from the mucus and the content of the gut sections and feces were optimized leading to 2802 nonredundant bacterial protein groups in total that were assigned to spectra measured by liquid chromatography-tandem mass spectrometry. The majority of 16S rRNA genes and protein groups belonged to members of Firmicutes, Bacteroidetes and Proteobacteria. The functionalities in the enzyme repertoire were compared between the mucus and the content of the large intestine sections and the feces samples. This spatial resolution allowed pinpointing changes in the community to specific metabolic capacities like carbohydrate transport and energy conservation. The results showed that the mere analysis of feces samples reflects the functions of the gut microbiota only to a minor extent and sheds light on the metabolic interchange between the microbiota and the host organism.

Palmitate Induced IL-6 and MCP-1 Expression in Human Bladder Smooth Muscle Cells Provides a Link between Diabetes and Urinary Tract Infections

Background Urinary tract infections (UTI) are more frequent in type-2 diabetes mellitus patients than in subjects with normal glucose metabolism. The mechanisms underlying this higher prevalence of UTI are unknown. However, cytokine levels are altered in diabetic patients and may thus contribute to the development of UTI. Increased levels of free fatty acids (FFA), as observed in obese patients, can induce IL-6 production in various cell types. Therefore we studied the effects of the free fatty acid palmitate and bacterial lipopolysaccharide (LPS) on interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1) expression and secretion in cultured human bladder smooth muscle cells (hBSMC). Methodology/Principal Findings Biopsies were taken from patients undergoing cystectomy due to bladder cancer. Palmitate or LPS stimulated hBSMC were analysed for the production and secretion of the IL-6, gp80, gp80soluble, gp130, MCP-1, pSTAT3, SOCS3, NF-κB and SHP2 by quantitative PCR, ELISA, Western blotting, and confocal immunofluorescence. In signal transduction inhibition experiments we evaluated the involvement of NF-κB and MEK1 in IL-6 and MCP-1 regulation. Palmitate upregulates IL-6 mRNA expression and secretion via NF-κB dependent pathways in a concentration- and time-dependent manner. MCP-1 was moderately upregulated by palmitate but was strongly upregulated by LPS involving NF-κB and MEK1 dependent pathways. Soluble IL-6 receptor (gp80soluble) was downregulated by palmitate and LPS, while membrane-bound gp80 was moderately upregulated. LPS increased SOCS3 and SHP2, whereas palmitate only induced SOCS3. Secondary finding: most of the IL-6 is secreted. Conclusions/Significance Bacterial infection (LPS) or metabolic alterations (palmitate) have distinct effects on IL-6 expression in hBSMC, (i) short term LPS induced autocrine JAK/STAT signaling and (ii) long-term endocrine regulation of IL-6 by palmitate. Induction of IL-6 in human bladder smooth muscle cells by fatty acids may represent a pathogenetic factor underlying the higher frequency and persistence of urinary tract infections in patients with metabolic diseases.

Cytokine Effects on Gap Junction Communication and Connexin Expression in Human Bladder Smooth Muscle Cells and Suburothelial Myofibroblasts

Background The last decade identified cytokines as one group of major local cell signaling molecules related to bladder dysfunction like interstitial cystitis (IC) and overactive bladder syndrome (OAB). Gap junctional intercellular communication (GJIC) is essential for the coordination of normal bladder function and has been found to be altered in bladder dysfunction. Connexin (Cx) 43 and Cx45 are the most important gap junction proteins in bladder smooth muscle cells (hBSMC) and suburothelial myofibroblasts (hsMF). Modulation of connexin expression by cytokines has been demonstrated in various tissues. Therefore, we investigate the effect of interleukin (IL) 4, IL6, IL10, tumor necrosis factor-alpha (TNFα) and transforming growth factor-beta1 (TGFβ1) on GJIC, and Cx43 and Cx45 expression in cultured human bladder smooth muscle cells (hBSMC) and human suburothelial myofibroblasts (hsMF). Methodology/Principal Findings HBSMC and hsMF cultures were set up from bladder tissue of patients undergoing cystectomy. In cytokine stimulated cultured hBSMC and hsMF GJIC was analyzed via Fluorescence Recovery after Photo-bleaching (FRAP). Cx43 and Cx45 expression was assessed by quantitative PCR and confocal immunofluorescence. Membrane protein fraction of Cx43 and Cx45 was quantified by Dot Blot. Upregulation of cell-cell-communication was found after IL6 stimulation in both cell types. In hBSMC IL4 and TGFβ1 decreased both, GJIC and Cx43 protein expression, while TNFα did not alter communication in FRAP-experiments but increased Cx43 expression. GJ plaques size correlated with coupling efficacy measured, while Cx45 expression did not correlate with modulation of GJIC. Conclusions/Significance Our finding of specific cytokine effects on GJIC support the notion that cytokines play a pivotal role for pathophysiology of OAB and IC. Interestingly, the effects were independent from the classical definition of pro- and antiinflammatory cytokines. We conclude, that connexin regulation involves genomic and/or post-translational events, and that GJIC in hBSMC and hsMF depend of Cx43 rather than on Cx45.

Bariatric surgery in severely obese adolescents improves major comorbidities including hyperuricemia.

OBJECTIVE Serum uric acid (sUA) is believed to contribute to the pathogenesis of metabolic comorbidities like hypertension, insulin-resistance (IR) and endothelial dysfunction (EDF) in obese children. The present pilot study investigated the association between sUA concentrations and loss of body weight following laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y-gastric bypass (RYGB) in severely obese adolescents. MATERIALS/METHODS 10 severely obese adolescents underwent either LSG (n=5) or RYGB (n=5). 17 normal weight, healthy, age- and gender-matched adolescents served as a normal weight peer group (NWPG). Pre- and 12 months postoperatively, sUA and relevant metabolic parameters (glucose homeostasis, transaminases, lipids) were compared. RESULTS Preoperatively, sUA was significantly elevated in patients with severe obesity compared to NWPG. Twelve months after LSG and RYGB, a significant decrease in sUA, BMI, CVD risk factors, hepatic transaminases, and HOMA-IR was observed. Reduction in SDS-BMI significantly correlated with changes in sUA. CONCLUSIONS sUA levels and metabolic comorbidities improved following bariatric surgery in severely obese adolescents. The impact of changes in sUA on long-term clinical complications of childhood obesity deserves further study.

Serum vaspin concentrations are decreased after exercise-induced oxidative stress.

Elevated visceral adipose tissue-derived serpin (vaspin) serum concentrations are associated with impaired insulin sensitivity, but increase unexpectedly after long-term physical training. We therefore investigated the effect of an acute exercise bout and the effects of vitamin supplementation on chronic exercise effect and on serum vaspin concentrations. We measured serum vaspin and thiobarbituric acid-reactive substances (TBARS) concentrations in 80 individuals before and after a 1-hour acute exercise bout and independently in 40 healthy young men who were randomly assigned to either antioxidant (vitamin C (1,000 mg/day) and vitamin E (400 IU/day)) or to no supplementation after a standardized 4-week physical training program as a post hoc analysis. Serum vaspin concentrations significantly decreased after acute physical exercise as well as after 4 weeks of training in individuals without antioxidants. Changes in vaspin serum concentration correlate with increased TBARS serum concentrations both in response to a 1-hour exercise bout (r = –0.42, p < 0.01) and to the 4-week training (r = –0.31, p < 0.05). Interestingly, supplementation with antioxidants rather increased circulating vaspin levels in response to 4 weeks of exercise. In conclusion, vaspin serum concentrations are decreased by exercise-induced oxidative stress, but not by exercise-associated improvement in insulin sensitivity.

Struktur und Funktion der suburothelialen Myofibroblasten in der humanen Harnblase unter normalen und pathologischen Bedingungen

BACKGROUND Myofibroblasts play a pivotal role in numerous pathological alterations. Clarification of the structure and function and of the cellular plasticity of this cell type in the bladder may lead to new insights into the pathogenesis of lower urinary tract disorders. PATIENTS AND METHODS Bladder biopsies from patients with bladder carcinoma and interstitial cystitis were used to analyse the morphology and receptor expression using confocal immunofluorescence and electron microscopy. Cytokine effects and coupling behavior were tested in cultured myofibroblasts and detrusor smooth muscle cells. RESULTS Myofibroblasts are in close contact with the suburothelial capillary network. They express Cx43 and form functional syncytia. The expression of muscarinic and purinergic receptors is highly variable. Dye coupling experiments showed differences to detrusor myocytes. CONCLUSIONS Upregulation of smooth muscle cell alpha-actin and/or transdifferentiation into smooth muscle cells may contribute to the etiology of urge incontinence. A multi-step model is presented as a working hypothesis.ZusammenfassungHintergrundBei zahlreichen pathologischen Veränderungen spielen Myofibroblasten eine wesentliche Rolle. Die Aufklärung der Struktur und Funktion sowie der zellulären Plastizität dieses Zelltyps in der Harnblase könnte zu einer neuen Beurteilung der Pathogenese von Harnabflusstörungen führen.Patienten und MethodenHarnblasenbiopsien von Tumorpatienten und Patienten mit interstitieller Zystitis wurden immunhistologisch und elektronenmikroskopisch untersucht. Kopplungseigenschaften wurden an kultivierten Myofibroblasten und Detrusormuskelzellen mit Hilfe von Farbstoffinjektion analysiert.ErgebnisseMyofibroblasten stehen in engem Kontakt zum suburothelialen Kapillarnetz. Sie exprimieren Cx43 und bilden funktionelle Synzytien. Die Expression von muskarinischen und purinergen Rezeptoren variiert sehr stark. In Farbstoffkopplungsexperimenten fanden wir Unterschiede zu Detrusormyozyten.DiskussionPathologische Expression von glattmuskulärem Aktin und/oder Transdifferenzierung zu glatten Muskelzellen könnten eine Rolle bei der Ätiologie der Dranginkontinenz spielen. Ein mehrstufiges Modell wird als Arbeitshypothese vorgeschlagen.AbstractBackgroundMyofibroblasts play a pivotal role in numerous pathological alterations. Clarification of the structure and function and of the cellular plasticity of this cell type in the bladder may lead to new insights into the pathogenesis of lower urinary tract disorders.Patients and methodsBladder biopsies from patients with bladder carcinoma and interstitial cystitis were used to analyse the morphology and receptor expression using confocal immunofluorescence and electron microscopy. Cytokine effects and coupling behavior were tested in cultured myofibroblasts and detrusor smooth muscle cells.ResultsMyofibroblasts are in close contact with the suburothelial capillary network. They express Cx43 and form functional syncytia. The expression of muscarinic and purinergic receptors is highly variable. Dye coupling experiments showed differences to detrusor myocytes.ConclusionsUpregulation of smooth muscle cell alpha-actin and/or transdifferentiation into smooth muscle cells may contribute to the ethiology of urge incontinence. A multi-step model is presented as a working hypothesis.

Free fatty acid palmitate impairs the vitality and function of cultured human bladder smooth muscle cells.

Background Incidence of urinary tract infections is elevated in patients with diabetes mellitus. Those patients show increased levels of the saturated free fatty acid palmitate. As recently shown metabolic alterations induced by palmitate include production and secretion of the pro-inflammatory cytokine interleukine-6 (IL-6) in cultured human bladder smooth muscle cells (hBSMC). Here we studied the influence of palmitate on vital cell properties, for example, regulation of cell proliferation, mitochondrial enzyme activity and antioxidant capacity in hBSMC, and analyzed the involvement of major cytokine signaling pathways. Methodology/Principal Findings HBSMC cultures were set up from bladder tissue of patients undergoing cystectomy and stimulated with palmitate. We analyzed cell proliferation, mitochondrial enzyme activity, and antioxidant capacity by ELISA and confocal immunofluorescence. In signal transduction inhibition experiments we evaluated the involvement of NF-κB, JAK/STAT, MEK1, PI3K, and JNK in major cytokine signaling pathway regulation. We found: (i) palmitate decreased cell proliferation, increased mitochondrial enzyme activity and antioxidant capacity; (ii) direct inhibition of cytokine receptor by AG490 even more strongly suppressed cell proliferation in palmitate-stimulated cells, while counteracting palmitate-induced increase of antioxidant capacity; (iii) in contrast knockdown of the STAT3 inhibitor SOCS3 increased cell proliferation and antioxidant capacity; (iv) further downstream JAK/STAT3 signaling cascade the inhibition of PI3K or JNK enhanced palmitate induced suppression of cell proliferation; (v) increase of mitochondrial enzyme activity by palmitate was enhanced by inhibition of PI3K but counteracted by inhibition of MEK1. Conclusions/Significance Saturated free fatty acids (e.g., palmitate) cause massive alterations in vital cell functions of cultured hBSMC involving distinct major cytokine signaling pathways. Thereby, certain cytokines might counteract the palmitate-induced downregulation of cell proliferation and vitality. This could be an important link to clinical findings of increased risk of metabolic related bladder diseases such as overactive bladder (OAB) and bladder pain syndrome/interstitial cystitis (BPS/IC).

Structure and function of suburothelial myofibroblasts in the human urinary bladder under normal and pathological conditions

BACKGROUND Myofibroblasts play a pivotal role in numerous pathological alterations. Clarification of the structure and function and of the cellular plasticity of this cell type in the bladder may lead to new insights into the pathogenesis of lower urinary tract disorders. PATIENTS AND METHODS Bladder biopsies from patients with bladder carcinoma and interstitial cystitis were used to analyse the morphology and receptor expression using confocal immunofluorescence and electron microscopy. Cytokine effects and coupling behavior were tested in cultured myofibroblasts and detrusor smooth muscle cells. RESULTS Myofibroblasts are in close contact with the suburothelial capillary network. They express Cx43 and form functional syncytia. The expression of muscarinic and purinergic receptors is highly variable. Dye coupling experiments showed differences to detrusor myocytes. CONCLUSIONS Upregulation of smooth muscle cell alpha-actin and/or transdifferentiation into smooth muscle cells may contribute to the etiology of urge incontinence. A multi-step model is presented as a working hypothesis.ZusammenfassungHintergrundBei zahlreichen pathologischen Veränderungen spielen Myofibroblasten eine wesentliche Rolle. Die Aufklärung der Struktur und Funktion sowie der zellulären Plastizität dieses Zelltyps in der Harnblase könnte zu einer neuen Beurteilung der Pathogenese von Harnabflusstörungen führen.Patienten und MethodenHarnblasenbiopsien von Tumorpatienten und Patienten mit interstitieller Zystitis wurden immunhistologisch und elektronenmikroskopisch untersucht. Kopplungseigenschaften wurden an kultivierten Myofibroblasten und Detrusormuskelzellen mit Hilfe von Farbstoffinjektion analysiert.ErgebnisseMyofibroblasten stehen in engem Kontakt zum suburothelialen Kapillarnetz. Sie exprimieren Cx43 und bilden funktionelle Synzytien. Die Expression von muskarinischen und purinergen Rezeptoren variiert sehr stark. In Farbstoffkopplungsexperimenten fanden wir Unterschiede zu Detrusormyozyten.DiskussionPathologische Expression von glattmuskulärem Aktin und/oder Transdifferenzierung zu glatten Muskelzellen könnten eine Rolle bei der Ätiologie der Dranginkontinenz spielen. Ein mehrstufiges Modell wird als Arbeitshypothese vorgeschlagen.AbstractBackgroundMyofibroblasts play a pivotal role in numerous pathological alterations. Clarification of the structure and function and of the cellular plasticity of this cell type in the bladder may lead to new insights into the pathogenesis of lower urinary tract disorders.Patients and methodsBladder biopsies from patients with bladder carcinoma and interstitial cystitis were used to analyse the morphology and receptor expression using confocal immunofluorescence and electron microscopy. Cytokine effects and coupling behavior were tested in cultured myofibroblasts and detrusor smooth muscle cells.ResultsMyofibroblasts are in close contact with the suburothelial capillary network. They express Cx43 and form functional syncytia. The expression of muscarinic and purinergic receptors is highly variable. Dye coupling experiments showed differences to detrusor myocytes.ConclusionsUpregulation of smooth muscle cell alpha-actin and/or transdifferentiation into smooth muscle cells may contribute to the ethiology of urge incontinence. A multi-step model is presented as a working hypothesis.

A global proteome approach in uric acid stimulated human aortic endothelial cells revealed regulation of multiple major cellular pathways

BACKGROUND Uric acid (UA) has been identified as one major risk factor for cardiovascular diseases. Lowering of serum UA levels improves endothelial function. The present study investigates for the first time concentration-dependent effects of UA on human aortic endothelial cells (HAEC) and the cellular pathways involved in global proteomic analysis. METHODS The concentration dependent effects of UA on HAEC were investigated by nanoLC-MS/MS and ingenuity pathway analysis to reveal putative cellular pathways. For verification of the identified pathways the abundance or activity of key proteins was measured using ELISA or Western blotting. NO production was quantified by confocal laser microscopy. RESULTS We identified ubiquitin-proteasome system (UPS) and eIF4 signaling as the major pathways regulated by UA. K-means clustering analysis revealed 11 additional pathways, of which NO, superoxide signaling and hypoxia were further analyzed. A complex regulatory network was detected demonstrating that 500μmol/L UA, which is well above the concentration regarded as pathological in clinical settings, led to diminishing of NO bioavailability. In addition a UA-dependent downregulation of eIF4, an upregulation of UPS and an increase in HIF-1α were detected. CONCLUSIONS Here we show for the first time, that increasing UA levels activate different sets of proteins representing specific cellular pathways important for endothelial function. This indicates that UA may alter far more pathways in HAEC than previously assumed. This regulation occurs in a complex manner depending on UA concentration. Further studies in knockout and overexpression models of the identified proteins are necessary to prove the correlation with endothelial dysfunction.