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To investigate the association of serum levels and the −2518 A→G promoter polymorphism of the gene for chemokine monocyte chemoattractant protein-1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, with metabolic parameters as well as insulin, leptin and the cytokines tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in 534 Caucasian patients with type 2 diabetes mellitus. MCP-1 concentrations were measured by enzyme-linked immunosorbent assay. MCP-1 genotyping was performed by RFLP analysis in a subset of 426 patients. Two hundred and thirty-one (54.2%) patients were homozygous for the wildtype allele (AA), 156 (36.6%) were heterozygous (AG) and 39 (9.2%) were homozygous for the mutated allele (GG). Allelic frequency was similar to non-diabetic populations (wildtype allele A: 0.73; mutated allele G: 0.27). MCP-1 mean concentrations and percentiles were substantially higher in non-diabetic populations but were not influenced by the genotype (AA: 662.0 ± 323.0 pg/ml; AG: 730.6 ± 491.4 pg/ml; GG: 641.2 ± 323.8 pg/ml). MCP-1 serum levels and genotypes were only marginally related to hormones (insulin and leptin) and cytokines (TNF-α and IL-6). This is the first study providing MCP-1 levels, percentiles and genotype frequency in a large and representative cohort of patients with type 2 diabetes mellitus. Compared to the literature, MCP-1 levels were found to be substantially higher in patients with type 2 diabetes mellitus. In contrast, genotype frequencies were similar compared to those in non-diabetic patients and were not related to MCP-1 levels. The mechanisms behind these elevated MCP-1 serum levels in type 2 diabetes are not to be explained by simple associations with hormones, cytokines or genotypes. [ABSTRACT FROM AUTHOR]

Abstract: Genomic structure, promoter region, amino acid sequence and exon-specific primer combinations of the human omentin gene are presented. Omentin mRNA expression differs between omental adipose tissue probes from patients with chronic inflammatory bowel diseases such as Crohn''s disease. Sequence comparisons revealed a 100% identity of omentin with human intelectin. Based on this, omentin might be a new adipocytokine playing a role in the defense against intestinal bacterial translocation in the context of Crohn''s disease. [Copyright &y& Elsevier]

Background and Aims: Ultra-microangiography (UMA) is a novel Doppler technique with optimized wall filtering that provides high sensitivity to low-velocity blood flows and optimized visualization of microcirculation. The aim of this pilot study was to compare intestinal vascularization assessed by color Doppler signals (CDS) and UMA., Methods: We investigated intestinal vascularization using UMA and CDS in 13 patients with confirmed inflammatory bowel disease (IBD). A cohort of 28 patients without structural bowel disease served as the control., Results: Microcirculation and dysregulated microcirculation in patients without and with inflammatory bowel disease can be visualized and quantified using UMA. In 83 % of IBD patients and 76% of non-IBD patients, a high resolution of intestinal perfusion could be achieved using UMA., Conclusions: To the best of our knowledge, this is the first study to investigate intestinal vascularization using UMA in patients with and without structural bowel disease. Quantification and visualization of intestinal vascularization should be further investigated in prospective studies and could help guide our therapy of patients with IBD.

Background: Accurate biomarkers for disease activity and progression in patients with inflammatory bowel disease (IBD) are a prerequisite for individual disease characterization and personalized therapy. We show that metabolic profiling of serum from IBD patients is a promising approach to establish biomarkers. The aim of this work was to characterize metabolomic and lipidomic serum profiles of IBD patients in order to identify metabolic fingerprints unique to the disease., Methods: Serum samples were obtained from 55 patients with Crohn's disease (CD), 34 patients with ulcerative colitis (UC), and 40 healthy control (HC) individuals and analyzed using proton nuclear magnetic resonance spectroscopy. Classification of patients and HC individuals was achieved by orthogonal partial least squares discriminant analysis and univariate analysis approaches. Disease activity was assessed using the Gastrointestinal Symptom Rating Scale., Results: Serum metabolome significantly differed between CD patients, UC patients, and HC individuals. The metabolomic differences of UC and CD patients compared with HC individuals were more pronounced than the differences between UC and CD patients. Differences in serum levels of pyruvic acid, histidine, and the branched-chain amino acids leucine and valine were detected. The size of low-density lipoprotein particles shifted from large to small dense particles in patients with CD. Of note, apolipoprotein A1 and A2 serum levels were decreased in CD and UC patients with higher fecal calprotectin levels. The Gastrointestinal Symptom Rating Scale is negatively associated with the concentration of apolipoprotein A2., Conclusions: Metabolomic assessment of serum samples facilitated the differentiation of IBD patients and HC individuals. These differences were constituted by changes in amino acid and lipoprotein levels. Furthermore, disease activity in IBD patients was associated with decreased levels of the atheroprotective apolipoproteins A1 and A2., (© 2023 Crohn’s & Colitis Foundation. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation.)

Compensation of matrix effects is the main obstacle to achieve accurate quantification in LC-MS/MS. Therefore, quantitative LC-MS/MS typically relies on addition of internal standards (ISs). Here, we present a systematic comparison of ISs from a routine LC-MS/MS method for bile acid (BA) analysis with a focus on tauro-conjugated. Both human serum based quality control (QC) and patient samples were quantified with a variety of stable isotope labeled (SIL) BAs including D 5 -tauro BAs. As expected, SIL-ISs that match the endogenous analytes provide the highest data quality (precision, accuracy). We could not observe systematic correlation of data quality with chemical similarity or proximity in retention time of ISs to the analyte. However, both accuracy and precision of QCs and patient's concentrations showed significant correlation. This provides evidence that calculation of matrix-based QCs with various ISs could be applied for the selection of ISs whenever matching SILs are not available. Moreover, data calculated without ISs exhibited a poor data quality for both QCs and patients' concentrations. Considering these results, data generated without ISs should be interpreted with great care and may not be suitable for proposal of biomarkers unless solid quantitative data could confirm initial findings.

Objectives: Several clinical studies have suggested the adipocytokine adiponectin is involved in the progression of rheumatoid arthritis (RA). From this point of view, adiponectin might present a new therapeutic target. However, as adiponectin also exerts beneficial effects in the human organism, a strategy that would allow its detrimental effects to be abolished while maintaining the positive effects would be highly favourable. To elucidate such a strategy, the authors analysed whether the different adiponectin isoforms induce diverging effects, especially with regard to rheumatoid arthritis synovial fibroblasts (RASF), a central cell type in RA pathogenesis capable of invading into and destroying cartilage., Methods: Affymetrix microarrays were used to screen for changes in gene expression of RASF. Messenger RNA levels were quantified by real-time PCR, protein levels by immunoassay. The migration of RASF and primary human lymphocytes was analysed using a two-chamber migration assay., Results: In RASF, the individual adiponectin isoforms induced numerous genes/proteins relevant in RA pathogenesis to clearly different extents. In general, the most potent isoforms were the high molecular weight/middle molecular weight isoforms and the globular isoform, while the least potent isoform was the adiponectin trimer. The chemokines secreted by RASF upon adiponectin stimulation resulted in an increased migration of RASF and lymphocytes., Conclusion: The results clearly suggest a pro-inflammatory and joint-destructive role of all adiponectin isoforms in RA pathophysiology, indicating that in chronic inflammatory joint diseases the detrimental effects outweigh the beneficial effects of adiponectin.

Background: The adipokine CTRP-3 (C1q/TNF-related protein-3) belongs to the C1q/TNF-related protein family which antagonizes the effects of lipopolysaccharide (LPS). The aim was to investigate the antiinflammatory and antifibrotic role of CTRP-3 in Crohn's disease (CD)., Methods: Mesenteric adipose tissue (MAT) of patients with CD or colonic cancer (CC) was resected. Human primary colonic lamina propria fibroblasts (CLPF) were isolated from controls and CD patients. Concentrations of chemokines and cytokines in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Expression of connective tissue growth factor (CTGF), collagen I, and collagen III was analyzed by real-time polymerase chain reaction (PCR). Recombinant CTRP-3 expressed in insect cells was used for stimulation experiments., Results: CTRP-3 is synthesized and secreted by MAT resected from patients with CD, ulcerative colitis (UC), CC, and sigma diverticulitis as well as by murine and human mature adipocytes. CTRP-3 had no effect on the basal secretion of MCSF, MIF, or RANTES in MAT of CD and control patients. LPS-stimulation (10 ng/mL) significantly increased IL-8 release in CLPF of CD patients and, to a lesser extent, in cells of controls and of fibrotic CD tissue. CTRP-3 significantly and dose-dependently reduced LPS-induced IL-8 secretion in CLPF within 8 hours after LPS exposure, whereas LPS-induced IL-6 and TNF release was not affected. CTRP-3 inhibited TGF-β production and the expression of CTGF and collagen I in CLPF, whereas collagen III expression remained unchanged., Conclusions: CTRP-3 exerts potent antiinflammatory and antifibrotic effects in CLPF by antagonizing the LPS pathway and by targeting the TGF-β-CTGF-collagen I pathway., (Copyright © 2011 Crohn's & Colitis Foundation of America, Inc.)

Aims/hypothesis: Obesity and insulin resistance are characterized by a chronic and low grade state of inflammation and the pro-inflammatory response of monocytes is affected in type 2 diabetes mellitus (T2D). We aimed to investigate whether LPS-induced monocytic cytokine and chemokine release depends on serum lipoprotein parameters in T2D patients., Methods: Primary human monocytes were isolated from 29 patients with known T2D and from 20 healthy volunteers. Anthropometric and disease-related parameters such as age, gender, BMI, WHR, diabetes duration, diabetes complications, and diabetes control (HbA1c) were documented. Monocytes were stimulated for 18 h with LPS (1 μg/ml). Unstimulated monocytes served as control. The supernatant concentrations of CCL2, CCL3, CCL4, CCL5, MIF and resistin were measured by ELISA., Results: LPS-stimulation significantly (p<0.001) increased CCL chemokine and resistin concentrations in healthy controls and in patients with T2D, whereas MIF release was not affected in both groups. LPS-induced CCL2 and resistin concentrations were significantly higher in T2D patients when compared to healthy controls. In T2D patients, LPS-induced CCL3 concentration was higher in males when compared to females (p=0.039) and supernatant resistin concentration upon stimulation with LPS showed a significant and positive correlation with age (r=0.6; p=0.001). LPS-induced CCL2 concentration was significantly and positively correlated with serum triglyceride concentration (r=0.4; p=0.009) in T2D patients. Furthermore, LPS-induced CCL4 concentration was significantly and positively correlated with total (r=0.4; p=0.035) and LDL cholesterol (r=0.4; p=0.033) concentration., Conclusions: LPS responsiveness of monocytes is altered in T2D and is affected by the respective serum lipoprotein metabolism., (© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York.)

Objectives: Peripancreatic necrosis determines clinical severity in acute pancreatitis. Early markers predicting peripancreatic necrosis and clinical severity are lacking. Because adipocytes of peripancreatic adipose tissue secret highly active adipocytokines, the aim of the study was to investigate whether adipocytokines are able to serve as early markers predicting peripancreatic necrosis and clinical severity., Methods: A total of 50 patients (20 women, 30 men) with acute pancreatitis were included in this noninterventional, prospective, and monocentric cohort study on diagnostic accuracy. Clinical severity was classified by the Ranson score and the APACHE (Acute Physiology And Chronic Health Evaluation) II score. Pancreatic and peripancreatic necrosis were quantified by using the computed tomography-based Balthazar score, the Schroeder score, and the pancreatic necrosis score. Adiponectin, leptin, and resistin were measured at admission and daily for at least 10 days by enzyme-linked immunosorbent assay., Results: In contrast to admission C-reactive protein values, admission resistin values were significantly correlated with clinical severity and even with clinical end points such as death and need for interventions. Admission resistin levels were significantly elevated in patients with higher pancreatic and extrapancreatic necrosis scores. It was shown by receiver-operator characteristics that admission resistin concentration provides a positive predictive value of 89% in predicting the extent of peripancreatic necrosis (area under the curve, 0.8; P=0.002; sensitivity, 80%; specificity, 70%) by using a cutoff value of 11.9 ng/ml., Conclusions: Admission resistin concentration serves as an early predictive marker of peripancreatic necrosis and clinical severity in acute pancreatitis. Resistin may have potential for clinical use as a new and diagnostic serum marker.

Objective: Rheumatoid arthritis (RA) is associated with increased production of adipokines, which are cytokine-like mediators that are produced mainly in adipose tissue but also in synovial cells. Since RA synovial fibroblasts (RASFs), lymphocytes, endothelial cells, and chondrocytes are key players in the pathophysiology of RA, this study was undertaken to analyze the effects of the key adipokine adiponectin on proinflammatory and prodestructive synovial effector cells., Methods: Lymphocytes were activated in part prior to stimulation. All cells were stimulated with adiponectin, and changes in gene and protein expression were determined by Affymetrix and protein arrays. Messenger RNA and protein levels were confirmed using semiquantitative reverse transcription-polymerase chain reaction (PCR), real-time PCR, and immunoassays. Intracellular signal transduction was evaluated using chemical signaling inhibitors., Results: Adiponectin stimulation of human RASFs predominantly induced the secretion of chemokines, as well as proinflammatory cytokines, prostaglandin synthases, growth factors, and factors of bone metabolism and matrix remodeling. Lymphocytes, endothelial cells, and chondrocytes responded to adiponectin stimulation with enhanced synthesis of cytokines and various chemokines. Additionally, chondrocytes released increased amounts of matrix metalloproteinases. In RASFs, adiponectin-mediated effects were p38 MAPK and protein kinase C dependent., Conclusion: Our previous findings indicated that adiponectin was present in inflamed synovium, at sites of cartilage invasion, in lymphocyte infiltrates, and in perivascular areas. The findings of the present study indicate that adiponectin induces gene expression and protein synthesis in human RASFs, lymphocytes, endothelial cells, and chondrocytes, supporting the concept of adiponectin being involved in the pathophysiologic modulation of RA effector cells. Adiponectin promotes inflammation through cytokine synthesis, attraction of inflammatory cells to the synovium, and recruitment of prodestructive cells via chemokines, thus promoting matrix destruction at sites of cartilage invasion.

No detailed data are available on hepatic clearance, postprandial release, and distribution profile of metabolically active adipokines in splanchnic blood compartments such as portal and hepatic veins. This would be a prerequisite for understanding the role of visceral adipose tissue-derived adipokines in metabolism. Adiponectin, resistin, leptin, and visfatin concentrations were measured by enzyme-linked immunosorbent assay in peripheral veins, arterial blood, hepatic veins, and portal veins in 50 patients with liver cirrhosis undergoing transjugular intrahepatic portosystemic shunt implantation, in 6 patients with normal liver function, and in fasted and fed rats. Adiponectin, leptin, resistin, and visfatin did not differ among blood compartments in normal-weight probands in the fasted state. Adiponectin and leptin levels were similar in patients with and without liver cirrhosis. Systemic visfatin levels were decreased and resistin levels were increased in liver cirrhosis. Visfatin secretion was higher from visceral than from peripheral subcutaneous adipose tissue in liver cirrhosis. There was no hepatic clearance of visfatin. Leptin secretion was higher from peripheral than from visceral adipose tissue. Leptin did not undergo hepatic clearance. Resistin and adiponectin did not differ between blood compartments in liver cirrhosis. Resistin concentrations increased upon feeding in rats, and there was an increase in the postprandial clearance of adiponectin by the liver. A postprandial increase of leptin concentrations was restricted to peripheral adipose tissue in rats. The results give insight into the dynamics of splanchnic adipokine concentrations and help critically interpret data derived from messenger RNA expression studies.

Aims/hypothesis: It was the aim to investigate the hypothesis that the new C1q/TNF-family member CTRP-3 (C1q/TNF-related protein-3) acts anti-inflammatory in human monocytes from healthy controls and patients with type 2 diabetes mellitus (T2D)., Methods: Monocytes were isolated from 20 healthy controls and 30 patients with T2D. IL-6 and TNF concentrations were measured by ELISA. CTRP-3 was expressed in insect cells and used for stimulation experiments., Results: Basal IL-6 and TNF were not different in control and in T2D monocytes. LPS-stimulation (1 microg/ml) significantly (p<0.001) increased IL-6 and TNF in the supernatants of control and in T2D monocytes to a similar extent. CTRP-3 (1 microg/ml) significantly (p=0.03) inhibited LPS-induced IL-6 in control monocytes but not in T2D monocytes. TNF upon co-stimulation with LPS and CTRP-3 was significantly (p=0.012) lower in control than in T2D monocytes. LPS-induced TNF concentration was significantly and positively correlated with serum total cholesterol and LDL cholesterol in T2D patients., Conclusions: CTRP-3 inhibits LPS-induced IL-6 and TNF release. This anti-inflammatory effect is lost in T2D. Serum cholesterol concentration affects the pro-inflammatory potential of LPS to induce TNF release from T2D monocytes in the presence or absence of CTRP-3. CTRP-3 might partly account for the pro-inflammatory state in T2D., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Compared with bone marrow-derived mesenchymal stem cells, adipose tissue-derived stromal cells (ADSC) do have an equal potential to differentiate into cells and tissues of mesodermal origin, such as adipocytes, cartilage, bone, and skeletal muscle. However, the easy and repeatable access to subcutaneous adipose tissue and the simple isolation procedures provide a clear advantage. Since extensive reviews focusing exclusively on ADSC are rare, it is the aim of this review to describe the preparation and isolation procedures for ADSC, to summarize the molecular characterization of ADSC, to describe the differentiation capacity of ADSC, and to discuss the mechanisms and future role of ADSC in cell therapy and tissue engineering. An initial effort has also been made to differentiate ADSC into hepatocytes, endocrine pancreatic cells, neurons, cardiomyocytes, hepatocytes, and endothelial/vascular cells. Whereas the lineage-specific differentiation into cells of mesodermal origin is well understood on a molecular basis, the molecular key events and transcription factors that initially allocate the ADSC to a lineage-specific differentiation are almost completely unknown. Decoding these molecular mechanisms is a prerequisite for developing novel cell therapies.

Background and Aim: Severe acute pancreatitis is characterized by lipase-induced peripancreatic fat cell necrosis. Because adipocytes secret several highly active molecules, the aim of the present study was to investigate the hypothesis that adipocytokines could serve as potential markers predicting peripancreatic necrosis and severity in acute pancreatitis., Methods: A total of 23 patients (11 females, 12 males) with acute pancreatitis were included and a computed tomography (CT) examination was available in 20 patients. Balthazar score, Schröder score, pancreatic necrosis score, Ranson score and APACHE II score were calculated, correlated with biochemical parameters and analyzed using receiver-operator characteristics (ROC) analysis. Adipocytokine serum levels were measured daily by enzyme-linked immunosorbent assay (ELISA) over 10 days after admission., Results: Resistin and leptin were significantly elevated in patients with severe pancreatitis and were correlated with a radiological scoring system for extrapancreatic necrosis. Whereas resistin correlated positively with clinical scoring systems, time until discharge and the need for interventions, leptin was correlated positively with C-reactive protein (CRP) levels. Resistin levels measured on the day of admittance had a positive predictive value of 93.3% (cut-off: >6.95 ng/mL) in predicting a Schröder score >3., Conclusion: Resistin, and to a lesser extent leptin, but not adiponectin levels are novel potential markers for extrapancreatic necrosis and severity of acute pancreatitis and should therefore be tested in larger cohorts of patients.

Background: Creeping fat represents a characteristic feature of Crohn's disease (CD), and adipose tissue secretes adipocytokines and chemokines/growth factors such as vascular endothelial growth factor (VEGF). Because VEGF serum levels and mucosal VEGF expression is elevated in CD patients, the aim of the present paper was to investigate creeping fat-derived VEGF secretion in CD., Material and Methods: Adipose tissue was obtained from creeping fat of 10 patients with CD. Mesenteric adipose tissue was resected from 13 patients with colon cancer (CC) and from seven patients with diverticulitis (DIV). Three fat tissue specimens per well, and several wells (6-8) per patient were incubated ex vivo for 24 h. The release of VEGF into the supernatant was measured by ELISA., Results: There was stable VEGF secretion from mesenteric adipose tissue of patients with CC or DIV and from creeping fat of patients with CD. Whereas the VEGF secretion rate was not different between patients with CD (465 +/- 98 pg/g fat per 24 h) and CC (399 +/- 48 pg/g fat per 24 h), VEGF secretion was significantly reduced in patients suffering from DIV (115 +/- 41 pg/g fat per 24 h; P < 0.0001 and P = 0.001, respectively). The CD patients treated with steroids had significantly lower VEGF secretion rates (294 +/- 42 pg/g fat per 24 h) than CD patients not receiving steroids (607 +/- 105 pg/g fat per 24 h; P = 0.001)., Conclusions: Creeping fat is an important source of VEGF secretion. The characteristics of the inflammatory changes in CD might be due to the lack of VEGF downregulation that is seen in DIV.

Background: Creeping fat represents a characteristic feature of Crohn's disease (CD) and adipose tissue is currently being recognized as a complex compartment secreting highly active molecules. Pro- or anti-inflammatory adipose tissue-derived secretory products (adipocytokines) might play a role in the pathogenesis of CD., Methods: Adipose tissue specimens were obtained from creeping fat contiguous to the involved intestine of 10 patients with CD. Mesenteric adipose tissue specimens resected in 13 patients with colon cancer (CC) and in seven patients with diverticulitis (DIV) served as controls. Three fat tissue specimens per well and n = 6-8 wells per patient were incubated ex vivo for 24 h. The release of regulated on activation, T-cell expressed and secreted (RANTES) and interleukin (IL)-10 into the supernatant was measured by ELISA., Results: Both RANTES and IL-10 secretion could be demonstrated from total adipose tissue explants. The RANTES secretion is increased from creeping fat in CD (3691 +/- 597 pg/g fat per 24 h) when compared to mesenteric adipose tissue from patients with CC (1690 +/- 191 pg/g fat per 24 h; P < 0.0001) or DIV (1672 +/- 336 pg/g fat per 24 h; P < 0.0001). In contrast, IL-10 secretion is downregulated significantly only in patients with DIV (1418 +/- 180 pg/g fat per 24 h; P = 0.016) when compared to CC patients (2368 +/- 259 pg/g fat per 24 h). Crohn's disease patients receiving steroids had a higher secretion rate of RANTES and IL-10., Conclusions: Both RANTES and IL-10 secretion can be detected from mesenteric adipose tissue and from creeping fat. The elevated RANTES and IL-10 secretion from creeping fat in CD is not due to a CD-specific effect but caused by steroid treatment.

There is increasing evidence that visceral adipose tissue is a causative risk factor for fatty liver and nonalcoholic steatohepatitis. Adipose tissue-derived secretory proteins are collectively named adipocytokines. Obesity and mainly visceral fat accumulation impair adipocyte function and adipocytokine secretion and the altered release of these proteins contributes to hypertension, impaired fibrinolysis and insulin resistance. This review summarizes recent findings on the role of the adipocytokines adiponectin, leptin and resistin in the context of hepatic insulin resistance, fatty liver and liver fibrosis. Elevated levels of resistin antagonize hepatic insulin action and raise plasma glucose levels. Leptin exerts insulin-sensitizing effects, but obesity has been linked to leptin resistance and low levels of circulating leptin receptor, indicating that high levels of leptin cannot mediate its beneficial effects. Adiponectin improves insulin sensitivity; however, low circulating adiponectin is found in the obese state. Adiponectin is an anti-inflammatory protein, whereas leptin augments inflammation and fibrogenesis. Disturbed adipocytokine secretion might, therefore, promote hepatic steatosis and the development of nonalcoholic steatohepatitis. The beneficial effects of the therapeutic approaches so far tested in the treatment of fatty liver disease and fibrosis might be due to the modulation of these adipocytokines.

Adipose tissue has long been regarded as a passive type of connective tissue that stores energy as triglycerides and releases energy as free fatty acids, however, this point of view has now changed. The wide variety of products expressed and secreted by adipose tissue, such as adiponectin, leptin, and resistin, mean that the total adipose tissue mass can be defined as a real endocrine organ. The anatomic, metabolic and biochemical characteristics of visceral adipose tissue make it interesting in the context of intestinal and mesenteric diseases. These characteristics include increased lipolysis, venous drainage via the portal vein and local glucocorticoid excess owing to the specific expression of 11-beta-hydroxysteroid-dehydrogenase type 1. In this review, the role of the visceral adipose tissue and its secretory products in intestinal and mesenteric diseases is systematically reviewed, with special focus on 'creeping fat' in Crohn's disease and mesenteric panniculitis.

Background: Resistin, a peptide hormone, has been discussed controversially as a missing link between obesity and insulin resistance. In contrast to resistin mRNA expression in adipose tissue, data on human serum levels in obesity and diabetes mellitus is scarce. The physiological range of serum resistin levels, reference values or adjusted percentiles have not yet been determined, making the interpretation of serum resistin concentrations quite difficult., Methods: Resistin serum concentrations were measured systematically by ELISA in 216 healthy controls, 555 patients with type 2 diabetes and 114 patients with type 1 diabetes. Mean values, median, and range were determined, and BMI-, gender-, and disease-adapted percentiles were calculated for all subgroups., Results: Age and gender did not have any influence on resistin levels. BMI and resistin levels were positively correlated in healthy controls (p = 0.02), albeit with a weak correlation coefficient. This correlation was absent in patients with type 1 and type 2 diabetes. In both genders, healthy controls had significantly higher resistin levels than patients with type 1 and type 2 diabetes (7.9 +/- 0.2 ng/ml vs. 5.7 +/- 0.2 ng/ml and 5.5 +/- 0.1 ng/ml, respectively; p < 0.0001). There was no correlation between resistin levels and occurrence of diabetic retinopathy or nephropathy., Conclusions: Serum resistin levels can be measured by ELISA over a broad range from 0.6 ng/ml up to 27.7 ng/ml, suggesting that percentiles might be helpful in the interpretation of an individuals resistin value. While age and gender do not influence resistin levels, BMI and occurrence of diabetes have to be considered.

Heterogeneity of peripheral blood monocytes is characterized by specific patterns in the membrane expression of Fc gamma-receptor III (FcgammaRIII/CD16) and the lipopolysaccharide receptor (LPS receptor CD14), allowing discrimination of distinct subpopulations. The aim was to analyze the correlation of these phenotypic differences to the early interaction of freshly isolated monocytes with modified lipoproteins by the use of either enzymatically degraded low density lipoprotein (E-LDL), acetylated low density lipoprotein (ac-LDL), oxidized low density lipoprotein (ox-LDL), or native low density lipoprotein. Highest E-LDL binding was observed on CD14(high) CD16(+) monocytes as determined by flow cytometry, suggesting a selective interaction of E-LDL with distinct subpopulations of monocytes. E-LDL induced rapid foam cell formation both in predifferentiated monocyte-derived macrophages and, in contrast to ac-LDL or ox-LDL, also in freshly isolated peripheral blood monocytes. This was accompanied by upregulation of the 2 class B scavenger receptors CLA-1/SR-BI (CD36 and LIMPII Analogous-1/scavenger receptor type B class I) and CD36. Cellular binding and uptake of E-LDL was neither competed by ac-LDL nor the class A scavenger-receptor inhibitor polyinosinic acid but was partially inhibited by an excess of ox-LDL. In predifferentiated monocyte-derived macrophages, an anti-CD36 antibody inhibited cellular binding and uptake of E-LDL by approximately 20%, suggesting that recognition of these hydrolase-modified low density lipoprotein particles is mediated only in part by the class B scavenger receptor CD36.

Background and Aims: Members of the family of ABC transporters are involved in different processes of sterol metabolism, and ABCA1 was recently identified as a key regulator of high-density lipoprotein (HDL) metabolism. Our aim was to further analyze the role of ABCA1 in cholesterol metabolism., Methods: ABCA1-deficient mice (ABCA1-/-) and wild-type mice were compared for different aspects of sterol metabolism. Intestinal cholesterol absorption was determined by a dual stable isotope technique, and analysis of fecal, plasma, and tissue sterols was performed by gas chromatography/mass spectrometry. Key regulators of sterol metabolism were investigated by Northern and Western blot analyses or enzyme activity assays., Results: ABCA1-disrupted sv129/C57BL/6 hybrid mice showed a significant reduction in intestinal cholesterol absorption. The decrease in cholesterol absorption was followed by an enhanced fecal loss of neutral sterols, whereas fecal bile acid excretion was not affected. Total body cholesterol synthesis was significantly increased, with enhanced 3-hydroxy-3-methyglutaryl-coenzyme A (HMG-CoA) reductase observed in adrenals and spleen. In addition, ABCA1-/- mice showed markedly increased concentrations of cholesterol precursors in the plasma, lung, intestine, and feces. Reduced HMG-CoA reductase messenger RNA and enzyme activity in the liver suggest that enhanced cholesterol synthesis in ABCA1-/- mice occurs in peripheral tissues rather than the liver., Conclusions: The metabolism of cholesterol and cholesterol precursors is markedly affected by a lack of ABCA1 function.

Members of the human ABC transporter A subfamily have gained considerable attention based on the recent findings that ABCA1 and ABCR (ABCA4) cause familial HDL-deficiency syndromes and distinct forms of hereditary retinopathies, respectively. Here we report the complete cDNA and the genomic organization of ABCA2, another member of the human ABC A transporter subfamily. The ABCA2 coding region is 7.3 kb in size and codes for a 2436 amino acid polypeptide that bears the typical features of a full-size ABC transporter. Among the known members of the ABC A subfamily ABCA2 shares highest homology with the cholesterol-responsive transporters ABCA1 (50%) and the recently cloned ABCA7 (44%). The ABCA2 gene comprises 48 exons which are localized within a genomic region of only 21 kb. Analysis of the putative ABCA2 promoter sequence revealed potential binding sites for transcription factors that are involved in the differentiation of myeloid and neural cells. Gene expression analysis in human macrophages showed that ABCA2 mRNA is induced during cholesterol import indicating that ABCA2 is a cholesterol-responsive gene. Our results suggest a potential role for ABCA2 in macrophage lipid metabolism and neural development.

Excessive uptake of atherogenic lipoproteins such as modified low-density lipoprotein complexes by vascular macrophages leads to foam cell formation, a critical step in atherogenesis. Cholesterol efflux mediated by high-density lipoproteins (HDL) constitutes a protective mechanism against macrophage lipid overloading. The molecular mechanisms underlying this reverse cholesterol transport process are currently not fully understood. To identify effector proteins that are involved in macrophage lipid uptake and release, we searched for genes that are regulated during lipid influx and efflux in human macrophages using a differential display approach. We report here that the ATP-binding cassette (ABC) transporter ABCG1 (ABC8) is induced in monocyte-derived macrophages during cholesterol influx mediated by acetylated low-density lipoprotein. Conversely, lipid efflux in cholesterol-laden macrophages, mediated by the cholesterol acceptor HDL(3), suppresses the expression of ABCG1. Immunocytochemical and flow cytometric analyses revealed that ABCG1 is expressed on the cell surface and in intracellular compartments of cholesterol-laden macrophages. Inhibition of ABCG1 protein expression using an antisense strategy resulted in reduced HDL(3)-dependent efflux of cholesterol and choline-phospholipids. In a comprehensive analysis of the expression and regulation of all currently known human ABC transporters, we identified an additional set of ABC genes whose expression is regulated by cholesterol uptake or HDL(3)-mediated lipid release, suggesting a potential function for these transporters in macrophage lipid homeostasis. Our results demonstrating a regulator function for ABCG1 in cholesterol and phospholipid transport define a biologic activity for ABC transporters in macrophages.

After transformation of the Streptomyces lividans chloramphenicol-sensitive, arginine-auxotrophic mutant strain AJ100 with a derivative of plasmid SCP2, some of the regenerated protoplasts contained an 8.2 kb DNA sequence amplified to several hundred copies per chromosome. The corresponding non-amplified sequence, called AUD4, was isolated from a lambda phage genomic library of S. lividans 1326. Two cytosine residues were the only directly repeated nucleotides at the ends of the element, indicating that AUD4 is a class I amplifiable sequence. The element mapped in the AseI-D fragment of the S. lividans chromosome, where other class I amplifications have been described. The complete element was sequenced and 10 ORFs were identified. Some of the deduced proteins are highly conserved in other organisms but a putative function could be attributed to only a few of them. Duplication of AUD4 by integration of an Escherichia coli plasmid carrying various parts of AUD4 and a thiostrepton-resistance gene in S. lividans AJ100, ZX7 or TK64 induced amplification of the integrated plasmid, AUD4 or both at high frequency.

Tangier disease (TD) is an autosomal recessive disorder of lipid metabolism. It is characterized by absence of plasma high-density lipoprotein (HDL) and deposition of cholesteryl esters in the reticulo-endothelial system with splenomegaly and enlargement of tonsils and lymph nodes. Although low HDL cholesterol is associated with an increased risk for coronary artery disease, this condition is not consistently found in TD pedigrees. Metabolic studies in TD patients have revealed a rapid catabolism of HDL and its precursors. In contrast to normal mononuclear phagocytes (MNP), MNP from TD individuals degrade internalized HDL in unusual lysosomes, indicating a defect in cellular lipid metabolism. HDL-mediated cholesterol efflux and intracellular lipid trafficking and turnover are abnormal in TD fibroblasts, which have a reduced in vitro growth rate. The TD locus has been mapped to chromosome 9q31. Here we present evidence that TD is caused by mutations in ABC1, encoding a member of the ATP-binding cassette (ABC) transporter family, located on chromosome 9q22-31. We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product. The identification of ABC1 as the TD locus has implications for the understanding of cellular HDL metabolism and reverse cholesterol transport, and its association with premature cardiovascular disease.

The human adipocyte-specific apM-1 gene encodes a secretory protein of the adipose tissue that has been suggested to play a role in the pathogenesis of obesity. The regulation of apM-1 was studied along adipocyte differentiation. While apM-1-mRNA and apM-1 protein were absent in preadipocytes and in 48 h differentiated adipocytes, they were found upregulated from day 4 to day 9 of adipocyte differentiation as shown by RNase protection assay and Western blot analysis. These data indicate that apM-1 may be a late marker of adipocyte differentiation. In human sera apM-1 protein is also detectable by Western blots using a polyclonal antibody raised against a synthetic peptide sequence of the human apM-1. The genomic structure of the human apM-1 gene together with a total of 2.7 kb of the 5'-flanking region with putative transcription factor binding sites is presented. Interestingly, sequence comparisons link the apM-1 gene to the family of TNF's and to genes expressed in activated T-cells. The chromosomal localization of apM-1 was investigated by FISH and mapped to human chromosome 1q21.3-1q23, a region that was identified as a susceptibility locus for Familial Combined Hyperlipidaemia (FCH) and polygenic NIDDM. These data and the chromosomal localization on chromosome 1q21.3-q23 raises the possibility that apM-1 as an adipocyte-specific secretory protein may play a role in the pathogenesis of FCH and associated insulin resistance. Exon- and intron-specific primer sequences are presented as a basis for mutation screening of patients affected with FCH., (Copyright 1999 Academic Press.)

Human lysosomal acid lipase (LAL) is a hydrolase required for the cleavage of cholesteryl esters and triglycerides derived from plasma lipoproteins. It is shown here that during monocyte to macrophage differentiation, the expression of LAL-mRNA is induced. This induction is dependent on protein kinase C activity and protein synthesis. The cell type-specific increase in LAL expression is further investigated in the THP-1 cell line with respect to transcriptional regulation. The human monocytic leukemia cell line THP-1 differentiates into macrophage-like cells when treated with phorbol esters. In order to determine the cis-acting elements necessary for both basal and phorbol 12-myristate-13 acetate (PMA)-enhanced promoter activity, we performed deletion analysis and reporter gene assays. A PMA responsive element has been identified between -182 bp and -107 bp upstream of the major transcription start site. Gel mobility shift assays demonstrated that binding of Sp1 and AP-2 to the LAL promoter is increased by PMA in THP-1 cells. Co-transfections with expression plasmids for Sp1 and AP-2 further emphasized the important role of these transcription factors in both basal and PMA-enhanced LAL expression. Our data suggest that differentiation dependent increase of lysosomal acid lipase (LAL) expression in THP-1 cells is mediated by a concerted action of Sp1 and AP-2.

We describe the genomic organization and the functional promoter of the monocyte specific gene Dif-2, the human homologue to genes in mouse (gly96) and rat (PRG1), that is downregulated during cell differentiation. The Dif-2 gene consists of two exons and a single intron of 112 bp in length. RNase protection assay indicates one major transcription start site. Sequence analysis reveals several consensus sequences for transcription factors including NF-kappa B, C/EBP, SP1, and the lack of a classical TATA-box. To demonstrate promoter activity, DNA fragments of the Dif-2 5'-flanking region were ligated upstream to the luciferase gene and transfected into HepG2 and HeLa cells. A minimal promoter element between nt -158 and nt +74 containing NF-kappa B and SP1 binding sites was shown to be sufficient for basal activity. These transcription factor binding sites, which are conserved between Dif-2, gly96, and PRG1 promoter regions, indicate a significant role for Dif-2 expression and may explain LPS and C2-ceramide sensitivity. The Dif-2 gene was mapped to chromosome 6p21.3 using in situ hybridization technique.

Cholesteryl ester storage disease (CESD) and Wolman disease (WD) are both autosomal recessive disorders associated with reduced activity of lysosomal acid lipase (LAL), that leads to the tissue accumulation of cholesteryl esters in endosomes and lysosomes. WD is caused by genetic defects of LAL that leave no residual enzymatic activity, while in CESD patients a residual LAL activity can be identified. We have analyzed the LAL cDNA in three CESD patients from two nonrelated families and identified the mutations responsible for the disease. The associated genetic defects characterized revealed compound heterozygosity for a splice defect leading to skipping of exon 8, due to a G-->A transition at position -1 of the exon 8 splice donor site, and a point mutation leading to a Hisl08Pro change (CAT-->CCT) in two patients (siblings) with mild CESD phenotype. A further CESD patient was hemizygous for a His108-->Arg missense mutation (CAT-->CGT) in combination with a partial deletion of the LAL gene and was affected more severely. Expression of the LAL enzymes with the His108-->Pro and His108-->Arg mutation in insect cells revealed residual enzymatic activities of 4.6% versus 2.7%, respectively, compared with controls. Therefore, His108 seems to play a crucial role in folding or catalytic activity of the lysosomal acid lipase. This is the first description of two different, naturally occurring mutations involving the same amino acid residue in the lysosomal acid lipase in unrelated CESD patients. Moreover, our results demonstrate that the variable manifestation of CESD can be explained by mutation-dependent, variable inactivation of the LAL enzyme.

We have identified the functional promoter of the translational inhibitor p14.5, the human homologue to a rat perchloric acid-soluble protein (PSP), a mouse heat-responsive protein (Hrp12) and a goat tumor antigen (UK114). Sequence analysis revealed a GC-rich promoter with several consensus sequences for transcription factors, but no TATA- and CAAT-box. To confirm promoter activity, DNA fragments of the p14.5 5'-flanking region were ligated in front of the luciferase gene and were transfected into HeLa and HepG2 cells. A minimal promoter between nt -104 and nt +88 relative to the transcription start site was responsible for basal activity. Furthermore, we observed a head-to-head orientation of p14.5 to the gene for the protein subunit of RNase P and MRP ribonucleoproteins (hPOP1). Luciferase assays with fragments of the hPOP1 5'-flanking region revealed a minimal promoter between nt -20 and nt +98 relative to the start of transcription. These data indicate that the 102 bp region between p14.5 and hPOP1 can act as a bidirectional promoter. The p14.5-hPOP1-cluster was mapped to chromosome 8q22 using in situ hybridization technique., (Copyright 1997 Academic Press.)

We have determined the exon/intron organization of the human lipopolysaccharide binding protein (LBP) and bactericidal permeability increasing protein (BPI) genes. The LBP gene spans approximately 28.5 kb and is composed of 14 exons while the 31.5-kb-long BPI gene is composed of 15 exons. Comparison of the genomic organization of the LBP and BPI genes together with the genomic structures of the PLTP (phospholipid transfer protein) and CETP (cholesteryl ester transfer protein) genes, which all together constitute a gene family of functionally related proteins, revealed high homology with a remarkable conservation of exon/intron transitions. The exon/intron junctions of the LBP, BPI, and PLTP genes are almost identical, with most of the exons being of the same size. In addition, functional domains are conserved in these proteins. The C-terminal octapeptide important for CETP anchoring in lipoprotein particles is also present in LBP, BPI, and PLTP. The LPS binding motif in exons 3 and 4 has been retained in LBP and BPI. Our results indicate that the LBP, BPI, and PLTP genes, and probably the CETP gene, may have evolved from a common primordial gene and may share similar functional properties.

A novel differentiation-dependent cDNA (DIF-2) has been isolated from human mononuclear phagocytes by differential display. The full-length cDNA was cloned and sequenced. DIF-2 consists of 156 amino acids and has a predicted isoelectric point of 8.84. The mRNA is expressed in freshly isolated monocytes and is downregulated significantly when monocytes are subjected to differentiation. A similar differentiation-dependent downregulation is observed in normal hepatocytes compared to undifferentiated HepG2 cells. The mRNA expression in monocytes is sensitive to lipopolysaccharide and ceramide which both strongly increase DIF-2 transcription, while lysophosphatidylcholine results in a weaker upregulation of DIF-2 expression. A DIF-2 homologous gene has been previously isolated from mouse fibroblasts and was shown to be a serum growth factor-inducible immediate early gene. Our results indicate that DIF-2 represents a gene which is regulated in differentiation processes and strongly responsive to lipopolysaccharide, ceramide and lysophosphatidylcholine.

Cholesteryl ester storage disease (CESD) and Wolman disease are both autosomal recessive disorders associated with reduced activity and genetic defects of lysosomal acid lipase (LAL). We provide evidence that the strikingly more severe course of Wolman disease is caused by genetic defects of LAL that leave no residual enzyme activity. In a CESD patient, a G --> A mutation at position -1 of the exon 8 splice donor site results in skipping of exon 8 in 97% of the LAL hnRNA originating from this allele, while 3% are spliced correctly, resulting in full-length LAL enzyme. The mutant LAL mRNA codes for a protein lacking amino acids 254 to 277. On the other allele, a G --> T mutation leads to a premature stop codon at Gly245, resulting in inactive LAL enzyme. In addition, the previously identified Leu179 --> Pro mutation is present on this allele, and the LAL mRNA is rendered unstable by the premature stop codon. Analysis of two children with Wolman disease showed that both were homozygous for a G --> A mutation at position +1 of the same splice donor site as for the CESD patient, leading to skipping of exon 8. In contrast to the CESD patient, no correctly spliced mRNA was detectable. We have also expressed a wildtype LAL cDNA and the mutant LAL cDNA from one Wolman patient in Sf9 and H5 insect cells. We demonstrate that the LAL enzyme generated from the wildtype LAL cDNA was active in homogenates from Sf9 and H5 cells, while the enzyme with the internal deletion of 24 amino acids originating from the LAL cDNA of the Wolman patient was not. The combined data provide evidence that the only functionally relevant genetic difference between the Wolman patients and the CESD patient is that the splice defect in Wolman, which affects one of the invariable nucleotides of the splice consensus sequences (position +1), does not permit any correct splicing, whereas the defect observed in CESD (position -1) allows some correct splicing (3% of total LAL mRNA) and therefore the synthesis of functional enzyme.