Valeria Guglielmi

Human epicardial adipose tissue induces fibrosis of the atrial myocardium through the secretion of adipo-fibrokines

AIMS Recent studies have reported a relationship between the abundance of epicardial adipose tissue (EAT) and the risk of cardiovascular diseases including atrial fibrillation (AF). However, the underlying mechanisms are unknown. The aim of this study was to examine the effects of the secretome of human EAT on the histological properties of the myocardium. METHODS AND RESULTS Samples of EAT and subcutaneous adipose (SAT), obtained from 39 patients undergoing coronary bypass surgery, were analysed and tested in an organo-culture model of rat atria to evaluate the fibrotic properties of human fat depots. The EAT secretome induced global fibrosis (interstitial and peripheral) of rat atria in organo-culture conditions. Activin A was highly expressed in EAT compared with SAT and promoted atrial fibrosis, an effect blocked using neutralizing antibody. In addition, Activin A levels were enhanced in patients with low left-ventricular function. In sections of human atrial and ventricular myocardium, adipose and myocardial tissues were in close contact, together with fibrosis. CONCLUSION This study provides the first evidence that the secretome from EAT promotes myocardial fibrosis through the secretion of adipo-fibrokines such as Activin A.

Omental adipose tissue fibrosis and insulin resistance in severe obesity.

Background/Objectives:The unresolved chronic inflammation of white adipose tissue (WAT) in obesity leads to interstitial deposition of fibrogenic proteins as reparative process. The contribution of omental adipose tissue (oWAT) fibrosis to obesity-related complications remains controversial. The aim of our study was to investigate whether oWAT fibrosis may be related to insulin resistance in severely obese population.Subjects/Methods:Forty obese subjects were studied by glucose clamp before undergoing bariatric surgery and thus stratified according to insulin resistance severity (M-value). From the first (Group B: n=13; M=1.9±0.7 mg kg−1 min−1) and the highest (Group A: n=14; M=4.5±1.4 mg kg−1 min−1) M-value tertiles, which were age-, waist- and body mass index-matched, oWAT samples were then obtained.Gene expression of collagen type I, III and VI, interleukin-6, profibrotic mediators (transforming growth factor (TGF)-β1, activin A, connective tissue growth factor), hypoxia inducible factor-1α (HIF-1α) and macrophage (CD68, monocyte chemotactic protein (MCP)-1, CD86, CD206, CD150) markers were analyzed by quantitative reverse transcription PCR. Adipocyte size and total fibrosis were assessed by histomorphometry techniques.Results:Fibrosis at morphological level resulted significantly greater in Group B compared with Group A, although collagens gene expression did not differ. Notably, collagen VI messenger RNA significantly correlated with collagen I, collagen III, HIF-1α, TGF-β1, CD68, MCP-1 and CD86 transcription levels, supporting their relation with fibrosis development.Conclusions:In conclusion, we show for the first time that human oWAT fibrosis in severe obesity is consistent with a higher degree of insulin resistance measured by glucose clamp. Therefore, collagen deposition could represent a maladaptive mechanism contributing to obesity-related metabolic complications.

Brody disease: insights into biochemical features of SERCA1 and identification of a novel mutation.

Brody disease is an inherited disorder of skeletal muscle function characterized by increasing impairment of relaxation during exercise. The autosomal recessive form can be caused by mutations in the ATP2A1 gene, which encodes for the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 1 (SERCA1) protein. We studied 2 siblings affected by Brody disease. The patients complained of exercise-induced delay of muscle relaxation and stiffness since childhood and had gene analysis of ATP2A1. Morphologic and biochemical studies were performed on a muscle biopsy from 1 patient. The biopsy showed fiber size variation and increased numbers of fibers with internal nuclei. Ultrastructural examination revealed dilatation of lateral cisternae and proliferation of tubular elements of the sarcoplasmic reticulum. By immunohistochemistry, SERCA1 was expressed in a normal pattern, but sarcoplasmic reticulum Ca2+-ATPase activity was significantly reduced. Immunoblotting after high-resolution 2-dimensional gel electrophoresis showed a significant difference in the amount of SERCA1 protein between the patient and controls. Both patients were found to have 2 previously unreported in-frame deletions in ATP2A1. Because SERCA1 protein has specific biochemical characteristics in our patient, these results underline the importance of a pathologic and biochemical analyses for the diagnosis. In addition, we describe 2 novel mutations in the ATP2A1 gene.

Parathyroid Hormone and Insulin Resistance in Distinct Phenotypes of Severe Obesity: A Cross-Sectional Analysis in Middle-Aged Men and Premenopausal Women

CONTEXT High levels of PTH are reported in obese individuals and related to increased cardiometabolic risk. OBJECTIVE Our objective was to evaluate whether the relationship between PTH, insulin resistance, and related metabolic parameters differ between metabolically healthy obese (MHO) and insulin-resistant obese (IRO) subjects. DESIGN AND SETTING We conducted a cross-sectional study among patients evaluated for bariatric surgery in our University Hospital. PATIENTS Patients initially included were 174 severely obese subjects (114 women, aged 40 ± 5 yr, body mass index of 45 ± 6 kg/m(2)) without diabetes, chronic kidney disease, or hyperparathyroidism. MHO (n = 43) and IRO (n = 86) subjects were identified according to quartiles of insulin resistance. MAIN OUTCOME MEASURES Fasting and postload glucose, insulin, total and high-density lipoprotein cholesterol, triglycerides, creatinine, calcium, phosphorus, PTH, 25-hydroxyvitamin D (25OHD), fibrinogen, and high-sensitivity C-reactive protein were assessed. Insulin sensitivity index was derived from a 75-g oral glucose tolerance test. Fat distribution and bone mineral density were assessed with dual-energy x-ray absorptiometry. RESULTS Although 25OHD levels were higher in MHO than in IRO subjects [72.23 (59.41-80.36) vs. 52.36 (41.98-62.57) nmol/liter, P = 0.002], PTH levels were comparable between groups (74.4 ± 13.2 vs. 72.1 ± 15.1 ng/liter, P = 0.34). No differences in serum calcium, phosphorus, bone mineral density, and renal function were detected. An independent inverse association between 25OHD and insulin resistance was seen in both groups. In contrast to IRO subjects, after adjusting for covariates, PTH levels were unrelated to insulin sensitivity index, fasting and postload glucose, insulin, and high-sensitivity C-reactive protein in MHO subjects. CONCLUSIONS MHO and IRO subjects show comparably high levels of circulating PTH, which are not associated with insulin resistance and related metabolic parameters in MHO subjects. Most of the associations observed in IRO subjects appear to be mediated by greater truncal fat mass.

Effects of whole body vibration plus diet on insulin-resistance in middle-aged obese subjects.

We investigated the early effects of whole body vibration (WBV) added to hypocaloric diet on insulin-resistance and other parameters associated with glucose regulation in sedentary obese individuals. We randomly assigned 34 patients to WBV plus hypocaloric diet (WBV group) or diet alone (CON group) for 8 weeks. Fasting and post-load glucose, insulin, lipids, C-reactive protein, tumor necrosis factor-α, leptin, adiponectin were assessed. Insulin sensitivity index (ISI) was derived from oral-glucose-tolerance test. Body composition was evaluated with dual-energy X-ray absorptiometry. Both groups lost approximately 5% of weight, with greater reduction of body fat in WBV than in CON (-7.1±1.2 Kg vs. -5.3±1.0 Kg, p=0.003). Percent variation of ISI was more pronounced in WBV than in CON group (+35±4% vs. + 22±5%, p=0.002), accompanied by slight improvement in post-load glucose (-1.07±0.02 vs. - 0.12±0.01 mmol/l, p=0.031) but without changes in fasting levels. Adiponectin significantly increased in WBV group compared with CON (p=0.021 for comparison) whereas no differences in leptin and inflammatory markers were observed. In middle-aged sedentary obese subjects, WBV added to hypocaloric diet for 8 weeks improved body composition, insulin-resistance, glucose regulation and adiponectin levels to a greater extent compared with diet alone. Efficacy and feasibility of this approach in the long term need to be ascertained.

Age-related different relationships between ectopic adipose tissues and measures of central obesity in sedentary subjects.

Accumulation of fat at ectopic sites has been gaining attention as pivotal contributor of insulin resistance, metabolic syndrome and related cardiovascular complications. Intermuscular adipose tissue (IMAT), located between skeletal muscle bundles and beneath muscle fascia, has been linked to physical inactivity, ageing and body mass index, but little is known about its relationship with the other AT compartments, in particular with increasing age. To address this issue, erector spinae IMAT, epicardial (EAT), intraabdominal (IAAT) and abdominal subcutaneous adipose tissue (SAT) were simultaneously measured by Magnetic Resonance Imaging (MRI) and related to waist circumference measurements and age in 32 sedentary subjects without cardiovascular disease (18 men; 14 women; mean age 48.5±14 years). Fasting glucose, triglycerides and HDL-cholesterol were also assessed. We observed that, after dividing individuals according to age (≤ or >50 years), IMAT and EAT depots were significantly more expanded in older subjects (63.2±8.3 years) than in the younger ones (38.4±5.2 years) (p<0.001). Overall, both IMAT and EAT showed stronger positive associations with increasing age (β = 0.63 and 0.67, respectively, p<0.001 for both) than with waist circumference (β = 0.55 and 0.49, respectively, p<0.01 for both) after adjusting for gender. In addition, the gender-adjusted associations of IMAT and EAT with waist circumference and IAAT were significant in individuals ≤50 years only (p<0.05 for all) and not in the older ones. In contrast, no age-related differences were seen in the relationships of IAAT and SAT with waist circumference. Finally, serum triglycerides levels turned out not to be independently related with ectopic IMAT and EAT. In conclusion, the expansion of IMAT and EAT in sedentary subjects is more strongly related to age than waist circumference, and a positive association of these ectopic depots with waist circumference and IAAT amount can be postulated in younger individuals only.

GLP-1 receptor independent pathways: emerging beneficial effects of GLP-1 breakdown products

The glucagon-like peptide-1 (GLP-1) axis has emerged as a major therapeutic target for the treatment of type 2 diabetes and, recently, of obesity. The insulinotropic activity of the native incretin hormone GLP-1(7–36)amide, which is mainly exerted through a unique G protein-coupled receptor (GLP-1R), is terminated via enzymatic cleavage by dipeptidyl peptidase-IV that generates a C-terminal GLP-1 metabolite GLP-1(9–36)amide, the major circulating form in plasma. GLP-1(28–36)amide and GLP-1(32–36)amide are further cleavage products derived from GLP-1(7–36)amide and GLP-1(9–36)amide by the action of a neutral endopeptidase known as neprilysin. Until recently, GLP-1-derived metabolites were generally considered metabolically inactive. However, emerging evidence indicates that GLP-1 byproducts have insulinomimetic activities that may contribute to the pleiotropic effects of GLP-1 independently of the canonical GLP-1R. The recent studies reporting the beneficial effects of the administration of these metabolites in vivo and in vitro are the focus of this review. Collectively, these results suggest that GLP-1 metabolites inhibit hepatic glucose production, exert antioxidant cardio- and neuroprotective actions, reduce oxidative stress in vasculature and have both anti-apoptotic and proliferative effects in pancreatic β-cells, putatively by the modulation of mitochondrial functions. These findings have implication in energy homeostasis, obesity and its associated metabolic and cardiovascular complications as well as incretin-based therapies for the treatment of diabetes and obesity.

C-peptide: A predictor of cardiovascular mortality in subjects with established atherosclerotic disease

Aim: Insulin resistance and type 2 diabetes are independent risk factors for cardiovascular diseases. Levels of C-peptide are increased in these patients and its role in the atherosclerosis progression was studied in vitro and in vivo over the past years. To evaluate the possible use of C-peptide as cardiovascular biomarkers, we designed an observational study in which we enrolled patients with mono- or poly-vascular atherosclerotic disease. Methods: We recruited 431 patients with stable atherosclerosis and performed a yearly follow-up to estimate the cardiovascular and total mortality and cardiovascular events. Results: We performed a mean follow-up of 56 months on 268 patients. A multivariate Cox analysis showed that C-peptide significantly increased the risk of cardiovascular mortality [Hazard Ratio: 1.29 (95% confidence interval: 1.02−1.65, p < 0.03513)] after adjustment for age, sex, diabetes treatment, estimated glomerular filtration rate and known diabetes status. Furthermore, levels of C-peptide were significantly correlated with metabolic parameters and atherogenic factors. Conclusion: C-peptide was associated with cardiovascular mortality independently of known diabetes status in a cohort of patients with chronic atherosclerotic disease. Future studies using C-peptide into a reclassification approach might be undertaken to consider its potential as a cardiovascular disease biomarker.

Elbow deformities in a patient with mandibuloacral dysplasia type A

Elbow Deformities in a Patient With Mandibuloacral Dysplasia Type A Valeria Guglielmi, Monica D’Adamo, Maria Rosaria D’Apice, Alfonso Bellia, Davide Lauro, Massimo Federici, Renato Lauro, Giuseppe Novelli, and Paolo Sbraccia* Department of Internal Medicine, University of Rome ‘‘Tor Vergata’’, Rome, Italy Department of Biopathology and Diagnostic Imaging, University of Rome ‘‘Tor Vergata’’, Rome, Italy

MicroRNA 21 is up-regulated in adipose tissue of obese diabetic subjects

We investigated miR21 expression in omental (OAT) and subcutaneous adipose tissue (SAT) from 16 obese subjects undergoing bariatric surgery. Patients were divided into two age- and BMI-matched groups according to the presence of type 2 diabetes (T2D). miR21 was not differently expressed in OAT and SAT. However, miR21 expression was two folds greater in adipose tissue in patients with T2D. Accordingly, in primary cultures of adipocytes from non diabetic overweight subjects, miR21 expression increased after 24-h exposure to high glucose and insulin. In conclusion, miR21 appears linked to insulin-resistance deterioration within its pathophysiologic progression from obesity to T2D.