Gabor Voros

Nutritionally Induced Obesity Is Attenuated in Transgenic Mice Overexpressing Plasminogen Activator Inhibitor-1

Objective—The objective of this study was to investigate the role of plasminogen activator inhibitor-1 (PAI-1) in adipose tissue development in vivo. Methods and Results—Transgenic (Tg) mice overexpressing murine PAI-1 under control of the adipocyte promoter aP2 and wild-type (WT) controls were kept on standard food (SFD) or on high-fat diet (HFD) for 15 weeks. The body weight and the weight of the isolated subcutaneous and gonadal fat deposits of the Tg mice kept on the HFD were significantly lower than those of the WT mice. The number of adipocytes in the adipose tissue was similar for Tg and WT mice on the HFD, but adipocyte hypotrophy and a significantly lower ratio of stroma cells/adipocytes were observed in the Tg mice. A significant negative correlation (P <0.01) was observed between expression of preadipocyte factor-1, which blocks adipocyte differentiation, and adipose tissue weight. Fasting insulin and total cholesterol levels on the HFD were lower in Tg than in WT mice. Conclusions—High circulating PAI-1 levels attenuate nutritionally induced obesity. This may be related to modifications in adipose tissue cellularity affecting weight and plasma metabolic parameters.

Impaired Adipose Tissue Development in Mice With Inactivation of Placental Growth Factor Function

Placental growth factor (PlGF)-deficient (PlGF−/−) and wild-type mice were kept on a standard-fat or high-fat diet for 15 weeks. With the standard-fat diet, the body weights of PlGF−/− and wild-type mice were comparable, whereas the combined weight of subcutaneous and gonadal adipose tissues was lower in PlGF−/− mice (P = 0.02). With the high-fat diet, PlGF−/− mice had a lower body weight (P < 0.05) and less total subcutaneous plus gonadal adipose tissue (P < 0.0001). Blood vessel size was lower in gonadal adipose tissue of PlGF−/− mice with both the standard-fat and high-fat diet (P < 0.05). Blood vessel density, normalized to adipocyte number, was significantly lower in subcutaneous adipose tissue of PlGF−/− mice fed the high-fat diet (P < 0.01). De novo adipose tissue development in nude mice injected with 3T3-F442A preadipocytes was reduced (P < 0.005) by administration of a PlGF-neutralizing antibody. Bone marrow transplantation from wild-type or PlGF−/− mice to wild-type or PlGF−/− recipient mice revealed significantly lower blood vessel density in PlGF−/− recipient mice without an effect on adipose tissue growth. Thus, in murine models of diet-induced obesity, inactivation of PlGF impairs adipose tissue development, at least in part as a result of reduced angiogenesis.

Differential expression of plasminogen activator inhibitor-1, tumor necrosis factor-α, TNF-α converting enzyme and ADAMTS family members in murine fat territories

Our objective was to investigate expression of A disintegrin and metalloproteinase (ADAM) and ADAM proteins with a thrombospondin (TS) motif (ADAMTS) family members in adipose tissue of lean and obese mice. Five-week-old male mice were kept on standard chow (SFD) or on high fat diet (HFD) for 15 weeks, and subcutaneous (SC) and gonadal (GON) adipose tissue, as well as mature adipocytes and stromal–vascular (S–V) cells were harvested. mRNA levels of plasminogen activator inhibitor-1 (PAI-1), tumor necrosis factor-a (TNF-a), ADAM-17 (TACE or TNF-a converting enzyme), ADAMTS-1 and ADAMTS-8 were quantified in isolated adipose tissues and cell fractions, and during differentiation of murine preadipocytes. The HFD resulted in a significantly enhanced weight of isolated SC and GON fat pads, and in enhanced blood levels of glucose, cholesterol and PAI-1. ADAM-17, TNF-a, PAI-1, ADAMTS-1 and ADAMTS-8 mRNA were detected in both SC and GON adipose tissue of lean mice (SFD). In SC adipose tissue of obese mice (HFD), the expression of ADAM17 and PAI-1 was enhanced and that of ADAMTS-1 reduced, whereas in GON adipose tissue expression of TNF-a was enhanced and that of ADAMTS-8 reduced. In lean and obese mice, expression of ADAM-17, ADAMTS-1 and ADAMTS-8 was higher in the S–V cell fraction than in mature adipocytes. During differentiation of murine 3T3-F442A preadipocytes, expression of ADAM-17 and ADAMTS-1 remained virtually unaltered, whereas that of ADAMTS-8 decreased as adipocytes matured. Several ADAM and ADAMTS family members are expressed in adipose tissue and during differentiation of preadipocytes. Modulation of their expression upon development of obesity is adipose tissue-dependent. D 2002 Elsevier Science B.V. All rights reserved.

Influence of membrane-bound tumor necrosis factor (TNF)-alpha on obesity and glucose metabolism

Summary.  Objective: To investigate the influence of transmembrane tumor necrosis factor (TNF)‐α on adipose tissue development and insulin‐mediated glucose metabolism. Methods and results: TNF‐α and lymphotoxin‐α‐deficient mice expressing non‐cleavable transmembrane TNF‐α (Tg‐tmTNF‐α) and TNF‐α/lymphotoxin‐α double knockout (control) mice were kept on high‐fat diet for 15 weeks. The food intake and feeding efficiency of Tg‐tmTNF‐α mice were significantly higher compared with control mice. At the end of the study, Tg‐tmTNF‐α mice had a significantly higher total body weight, as well as subcutaneous and gonadal adipose tissue mass. Histological analysis revealed that the expression of Tg‐tmTNF‐α resulted in a significantly increased adipocyte area and blood vessel density. Plasma leptin levels correlated positively with adipose tissue mass. The plasma levels of total cholesterol and HDL‐cholesterol were significantly increased and LDL‐cholesterol levels significantly decreased in Tg‐tmTNF‐α mice. Fasting blood glucose and plasma insulin levels were not different between the two genotypes and intraperitoneal glucose and insulin tolerance tests did not show significant differences. Conclusions: Transmembrane TNF‐α enhances adipose tissue formation without altering insulin‐mediated glucose metabolism in mice with nutritionally induced obesity.

Overexpression of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in mice does not affect adipogenesis or adipose tissue development.

In order to evaluate a potential functional role of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in development of obesity, we studied the effect of overexpression of human TIMP-1 (hTIMP-1) in C57Bl/6J mice in vivo and in 3T3-F442A preadipocytes in vitro. Stable long-term overexpression of hTIMP-1 in mice was achieved by adenoviral gene transfer, yielding plasma levels exceeding 250 ng/ml at eight weeks after injection. Mice overexpressing hTIMP-1 and kept on a high fat diet for 14 weeks had body weights, adipose tissue weights, and adipocyte diameters that were somewhat, but not significantly, lower than those of control mice. Similar observations were made after overexpression of hTIMP-1 in mice with lipectomy of the subcutaneous adipose tissue, kept on a high fat diet for 20 weeks. In both in vivo models, blood vessels in the adipose tissues were significantly smaller after hTIMP-1 gene transfer than in control mice. Overexpression of hTIMP-1 in 3T3-F442A preadipocytes had no effect on their subsequent differentiation into mature adipocytes. Thus, overexpression of hTIMP-1 in mice had no significant effect on ongoing adipogenesis or adipose tissue development, although the blood vessel size in adipose tissues was reduced.

Deficiency of thrombospondin-1 in mice does not affect adipose tissue development.

Thrombospondin-1 (TSP-1) is a 420 kDa matricellular glycoprotein released by platelets during the formation of a hemostatic plug. It has been implicated in cell–matrix and cell–cell interactions that play an important role in platelet function, angiogenesis, tumor biology, wound healing and vascular disease [1]. Despite this pleiotropic biological role, mice deficient in TSP-1 are viable and exhibit only subtle abnormalities in development, although they develop pneumonia [2], and show delayed organization and prolonged neovascularization of skin wounds [3]. Interestingly, TSP-1 is expressed by intra-abdominal adipose tissue of rats and humans [4,5] and its expression is markedly regulated during the differentiation of preadipocytes into mature adipocytes [6,7]. We have recently shown that mRNA and protein levels of TSP-1 are upregulated in developing adipose tissue of mice with nutritionally induced or genetically determined obesity [8]. Because of its multifunctional nature, TSP-1 has been shown to both stimulate and inhibit angiogenesis, depending on the cellular context [1]. Angiogenesis in turn is generally believed to be ongoing during development of obesity [9]. To test the hypothesis that an effect of TSP-1 on angiogenesis may affect adipogenesis and adipose tissue development, we have kept 5-week-old male and female TSP-1 deficient (TSP-1 )/) )m ice and wild-type (TSP-1 +/+ ) littermates (genetic background C57Bl/6) on a high-fat diet (HFD, Harlan TD 88137, Zeiss, the Netherlands; containing 42% kcal as fat, and a caloric value of

Changes in Implantation Patterns and Therapy Rates of Implantable Cardioverter Defibrillators over Time in Ischemic and Dilated Cardiomyopathy Patients.

Clinical guidelines on implantable cardioverter defibrillator (ICD) therapy changed significantly in the last decades with potential inherent effects on therapy efficacy. We aimed to study therapy rates in time and the association between therapies and mortality.

Leptin-adiponectin ratio in pre-diabetic patients undergoing percutaneous coronary intervention.

Background The obesity-related hormones leptin and adiponectin are independently and oppositely associated with insulin resistance, which is an important risk factor for coronary artery disease (CAD) and restenosis after coronary intervention. In this report, we set out to determine the role of the leptin-adiponectin ratio (LAR) in non-diabetic patients with or without impaired glucose tolerance undergoing a percutaneous coronary intervention. Methods 300 PCI patients were enrolled in this prospective single-centre study. Patients with known diagnosis of diabetes (n = 50) and newly diagnosed diabetes (2h OGTT > 200 mg/dL, n = 25) were excluded. In both stable and acute subjects, assessment was done on the day of discharge and included a fasting glucose level, leptin, adiponectin and an oral glucose tolerance test (OGTT). Results LAR was significantly higher in diabetic (7.2 ± 0.7) than in non-diabetic patients (3.9 ± 0.3, P = 0.001), and even higher in newly diagnosed diabetics (9.8 ± 1.5, P < 0.001). Likewise, among non-diabetic patients, LAR was significantly higher in patients with impaired glucose tolerance. LAR was significantly higher in pre-diabetic (4.57 ± 0.48) versus normoglycaemic patients (3.45 ± 0.33, P = 0.05). LAR was found to be numerically higher in prediabetic versus normoglycaemic patients with two- and three-vessel disease (VD), but not in patients with single VD. In pre-diabetic patients, LAR was found to be significantly increased with more advanced CAD (P = 0.021), independent of stable versus unstable presentation. Conclusions LAR is related to the extent of CAD in pre-diabetic patients but not in normoglycaemic patients. This finding might in part explainthe poorer outcome in revascularized patients with impaired glucose tolerance compared to normoglycaemic patients.

Spontaneous rupture of a papillary muscle in acute myocarditis

A 33-year-old male patient was admitted to the coronary care unit with an infl ammatory syndrome and elevated troponin T. Shortly after admission the patient developed cardiogenic shock due to an anterior papillary muscle rupture and died after an urgent surgical replacement of the mitral valve. Histological examination of the excised papillary muscle showed signs of an acute myocarditis but no myocardial ischaemia. This case represents the fi rst description of a papillary muscle rupture, a potentially lethal complication, due to acute myocarditis.

Impairment of adipose tissue development by hypoxia is not mediated by plasminogen activator inhibitor-1.

Hypoxia in rodents and humans is associated with a reduction of body fat on the one hand, and with enhanced expression of plasminogen activator inhibitor-1 (PAI-1), the main inhibitor of the fibrinolytic system, on the other hand. It was the objective of this study to investigate whether impairment of adipose tissue development by hypoxia may be mediated by PAI-1. Five week old male wild-type (WT) C57Bl/6 mice were fed a standard (SFD) or high fat (HFD) diet and kept under normoxic or hypoxic (10% O(2)) conditions. In addition, PAI-1 deficient mice and WT littermates were kept on HFD under normoxia or hypoxia. In vitro, the effect of hypoxia (2% O(2)) was investigated on differentiation of 3T3-L1 cells into adipocytes. Hypoxia induced a significant reduction of weight gain in WT mice on either SFD or HFD, accompanied by lower weights of subcutaneous (SC) and gonadal (GON) fat. Under hypoxic conditions, adipocytes in the adipose tissues were significantly smaller, whereas blood vessel size and density were larger. Serum PAI-1 levels were enhanced in hypoxic mice on SFD but not on HFD, and overall did not correlate with the observed changes in adipose tissue composition. Furthermore, the effects of hypoxia on adipose tissue in mice on HFD were not affected by deficiency of PAI-1. The inhibiting effect of hypoxia on in vitro preadipocyte differentiation was not mediated by PAI-1 activity. In conclusion, impairment of in vivo adipose tissue development and in vitro differentiation of preadipocytes by hypoxia is not mediated by PAI-1.