Association of 1-deoxy-sphingolipids with steatosis but not steatohepatitis nor fibrosis in non-alcoholic fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most important cause of chronic liver disease in the western world. Steatosis can be accompanied by inflammation and cell damage (non-alcoholic steatohepatitis, NASH), and even liver fibrosis. Sphingolipids are a heterogeneous class of lipids and essential components of the plasma membrane and plasma lipoproteins. The atypical class of deoxy-sphingolipids has been implicated in the metabolic syndrome and type 2 diabetes. AIM: To determine if circulating (deoxy)sphingolipids are associated with NAFLD and its different entities, steatosis, inflammatory changes (inflammation and ballooning) and fibrosis. METHODS: Sphingolipids were analysed by LC-MS after hydrolysing the N-acyl and O-linked headgroups in plasma of obese adults who underwent a liver biopsy in suspicion of NAFLD. RESULTS: Two-hundred and eighty-eight patients were included. There was no association between typical sphingolipids and NAFLD and its different entities. There was a significant association between the presence of steatosis and the concentrations of deoxy-sphinganine [exp(B) 11.163 with CI (3.432, 36.306) and p < 0.001] and deoxy-sphingosine [exp(B) 8.486 with CI (3.437, 20.949) and p < 0.001]. There was no association between these deoxy-sphingolipids and activity of the steatohepatitis, nor was there any association with fibrosis. Differences in deoxy-sphingolipids also correlated independently with the presence of the metabolic syndrome, but not diabetes. CONCLUSION: Deoxy-sphingolipids are elevated in patients with steatosis compared to those without fatty liver, but not different between the different NAFLD subtypes, suggesting that deoxy-sphingolipid bases might be involved in steatogenesis, but not in the further progression of NAFLD to NASH nor in fibrogenesis.

Visceral adipose tissue and inflammation correlate with elevated liver tests in a cohort of overweight and obese patients.

OBJECTIVE: To study the relationship between elevated liver tests and high sensitive C-reactive protein (hs-CRP), as potential markers of liver inflammation and non-alcoholic steatohepatitis (NASH), with anthropometric and laboratory parameters in overweight patients, especially the relationship with visceral adipose tissue (VAT). METHODS: Patients presenting to the obesity clinic were prospectively included. Detailed anthropometry, computed tomography (CT)-measured VAT, liver tests (aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT)) and hs-CRP were assessed, along with an extended series of biochemical parameters. RESULTS: All 480 patients (gender distribution male (M)/female (F) (10/90%)) with complete data were included. Mean age was 39+/-13 years, mean BMI 34.5+/-6.0 kg m(-2). In 37.3% of the patients one or more of the liver tests were elevated. VAT was positively related to AST (r=0.18, P<0.001), ALT (r=0.29, P<0.001), ALP (r=0.16, P<0.01) and GGT (r=0.39, P<0.001). Comparing subjects with high (VAT>or=113 cm(2)) vs low (VAT<113 cm(2)) VAT levels, significant differences were noted for AST (26+/-12 vs 24+/-12 U l(-1), P=0.003), ALT (37+/-21 vs 31+/-21 U l(-1), P<0.001), ALP (76+/-20 vs 71+/-18 U l(-1), P=0.008), GGT (33+/-20 vs 25+/-15 U l(-1), P<0.001) and hs-CRP (0.62+/-0.43 vs 0.52+/-0.48 mg dl(-1), P<0.001). After correction for BMI the difference in AST and ALP between the high vs low VAT group disappeared. The differences for ALT and GGT remained significant (P=0.008 and P<0.001 respectively). After correction for hs-CRP the four different liver tests remained significantly higher in the high VAT group. A stepwise multiple regression analysis revealed that every single liver test has his own most important determinant; VAT and hs-CRP for AST, insulin resistance calculated with homeostasis model assessment (HOMA-IR) and hs-CRP for ALT and ALP, and triglycerides and VAT for GGT. CONCLUSION: In overweight and obese patients, liver tests, especially ALT and GGT, are associated with visceral fat mass. After correction for BMI and hs-CRP, ALT and GGT are significantly higher in patients with increased VAT, thereby supporting evidence for a potential key role of VAT in the pathogenesis of non-alcoholic fatty liver disease (NAFLD).

New approaches for the management of patients with multiple cardiometabolic risk factors.

Therapeutic strategies currently available for the management of cardiometabolic risk factors focus mainly on individual factors, and do not target the underlying cause of cardiovascular and metabolic diseases. The Rimonabant-in-Obesity (RIO) programme consists of four 1-2 yr Phase III trials, RIO-Europe, RIO-Lipids, RIO-North America (NA), and RIO-Diabetes, designed to assess the efficacy and safety of rimonabant in the treatment of multiple cardiometabolic risk factors in 6600 overweight/obesity patients. After 1 yr, results from the RIO-NA anci RIO-Europe trials, showed that treatment with rimonabant 20mg/day improved HDL-C (p< 0.001), triglycerides (p< 0.001), fasting insulin (p< 0.001) and insulin resistance (p=0.002 and p< 0.001 for RIO-Europe and RIO-NA, respectively) compared to placebo. The results of both studies also showed significant and sustained mean reductions in waist circumference (p< 0.001), and weight (p< 0.001) for rimonabant 20 mg/day compared with placebo. Similar improvements were seen in the RIO-Lipids trial at 1 yr and these results were consistently maintained over 2 yr in RIO-NA. The RIO-Europe and RIO-NA trials showed that improvements in HDL-C and TG levels with rimonabant over 1 yr, compared with bodyweight, were beyond that attributable to weight loss alone [40 and 55% for HDL-C and triglyceride (TG), respectively for RIO-Europe and 58 and 47%, respectively for RIO-NA]. Additionally, in RIO-NA, changes in fasting insulin and homeostasis model assessment insulin resistance (HOMA-IR), were beyond weight loss alone (50 and 51%, respectively). Rimonabant was well tolerated and the majority of adverse events reported were mild and transient, and occurred early in the treatment period. Rimonabant, the first cannabinoid receptor type 1 (CB1) receptor blocker, reduces weight and waist circumference, and improves lipid and glucose metabolism.

Leptin levels in type 2 diabetes: associations with measures of insulin resistance and insulin secretion.

Interactions between leptin and insulin have been shown previously, in vitro and in vivo. In this study, we evaluate the associations of leptin levels with insulin secretion and insulin sensitivity in type 2 diabetes. Fasting leptin levels, HbA 1c, glucose, insulin, C-peptide, intact and des-31,32-proinsulin were measured in 100 non-insulin-treated type 2 diabetic patients. Glucose, insulin and C-peptide were measured 2 hours after an oral glucose load. Insulin resistance and beta-cell function were calculated using HOMA. Leptin levels were found to be associated with all measures of beta-cell secretion: with fasting and 2 hours insulin and C-peptide, with intact and des-31,32-proinsulin concentrations, and with beta-cell secretion estimated with HOMA. This association was independent of age and body fat in women, but in men, associations with insulin and C-peptide weakened after controlling for fat mass, whereas those with intact and des-31,32-proinsulin disappeared. Fasting insulin and C-peptide levels were also significant in multiple regression analyses, besides gender and fat mass. Insulin resistance, as assessed by HOMA, was strongly correlated with leptin, also after correction for age and fat mass in both genders. We conclude that, besides fat mass and gender - the main determinants for leptin levels in type 2 diabetic subjects as in healthy subjects - insulin secretion and the degree of insulin resistance also seem to contribute significantly to leptin levels.

Visceral fat is a determinant of PAI-1 activity in diabetic and non-diabetic overweight and obese women.

Plasminogen activator inhibitor type 1 (PAI-1), an inhibitor of fibrinolysis and an important and independent cardiovascular risk factor, has been shown to be elevated in obesity and type 2 diabetes. Recent study results have suggested that adipose tissue--visceral fat in particular--could play an important role in the fibrinolytic process.In order to assess the specific role of this fat distribution, we measured PAI-1 activity (AU/ml) and visceral fat (CT-scan at level L4-L5) in 2 groups of 30 overweight and obese diabetic and overweight and obese non-diabetic women. Subjects were matched for age, weight, body mass index, fat mass and total abdominal fat. Visceral adipose tissue and PAI-1 were significantly higher in diabetic women (p = 0.022 and p = 0.004 respectively) than in non-diabetic patients. Visceral fat correlated significantly with PAI-1 activity, even after correction for insulin and triglycerides (r = 0.28, p = 0.034). Stepwise regression analysis showed visceral fat as the most important determinant factor for PAI-1 in the whole group and in the non-diabetic group. In the diabetic group, fasting insulin was the most important determinant. These results show that visceral fat is more important than BMI or total body fat in the determination of PAI-1 levels. Furthermore, the increased amount of visceral fat in type 2 diabetics may contribute to the increase of PAI-1 activity levels and the subsequent increased risk for thrombovascular disease, regardless of BMI and total fatness.

The importance of obesity in diabetes and its treatment with sibutramine.

Weight gain is a known risk factor for the development of type 2 diabetes and even modest weight reduction can reduce the risk of developing diabetes, so controlling body weight is an important public health goal in the fight against diabetes and its comorbidities. Weight reduction is also a cornerstone of diabetes management, improving glycaemic control and reducing other risk factors associated with this disease. Pharmacotherapies such as sibutramine contribute to the management of type 2 diabetes in overweight and obese patients.

Sibutramine and fat distribution: is there a role for pharmacotherapy in abdominal/visceral fat reduction?

Visceral adiposity has a strong and independent association with obesity and its related co-morbidities, particularly metabolic complications such as cardiovascular disease and type II diabetes. Waist circumference and waist-to-hip ratio (WHR) are both secondary indicators of visceral obesity. This paper examines the effect of sibutramine, a new serotonin and noradrenaline re-uptake inhibitor, on weight reduction and changes in fat distribution. A meta-analysis of four long-term, placebo-controlled, double-blind studies showed significantly greater mean decreases in waist circumference in sibutramine-treated subjects compared with placebo (P < 0.001). Similar results were seen for WHR, with 15 mg sibutramine daily producing a significant reduction of 0.02 compared with placebo (P < 0.02). Changes in fat distribution have been examined using computerised tomography (CT) scans as part of the Sibutramine Trial of Obesity Reduction and Maintenance (STORM). Preliminary results showed a mean weight loss from baseline of 11.2 +/- 6.3 kg after 6 months of 10 mg sibutramine treatment. Decreases in total abdominal fat (18%), total subcutaneous fat (17%) and total visceral fat (22%) were observed, and there was a significant increase in the subcutaneous-to-visceral fat ratio (P = 0.04). These changes in fat levels and distribution were associated with improvements in related risk factors such as fasting blood glucose and insulin levels, and blood pressure. In conclusion, sibutramine produces statistically and clinically significant decreases in waist circumference and WHR, and preferentially reduces visceral fat levels.