The association between non-alcoholic fatty liver disease and carotid atherosclerosis in subjects with within-reference range alanine aminotransferase levels

NAFLD in type 1 diabetes: overrated or underappreciated?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in western countries, affecting 25-30% of the general population and up to 65% in those with obesity and/or type 2 diabetes. Accumulation of visceral adipose tissue and insulin resistance (IR) contributes to NAFLD. NAFLD is not an innocent entity as it not only may cause nonalcoholic steatohepatitis and cirrhosis but also contribute to cardiovascular morbidity and mortality. More and more people with type 1 diabetes (T1D) are becoming overweight and present with features of IR, but the prevalence and impact of NAFLD in this population are still unclear. The utility of noninvasive screening tools for NAFLD in T1D is being explored. Recent data indicate that based upon ultrasonographic criteria NAFLD is present in 27% (ranging between 19% and 31%) of adults with T1D. Magnetic resonance imaging data indicate a prevalence rate of 8.6% (ranging between 2.1% and 18.6%). There are, however, multiple factors affecting these data, ranging from study design and referral bias to discrepancies in between diagnostic modalities. Individuals with T1D have a 7-fold higher risk of cardiovascular disease (CVD) and cardiovascular mortality is the most prominent cause of death in T1D. Patients with T1D and NALFD are also more prone to develop CVD, but the independent contribution of NAFLD to cardiovascular events has to be determined in this population. Furthermore, limited data in T1D also point towards a 2 to 3 times higher risk for microvascular complications in those with NAFLD. In this article, we will discuss epidemiological and diagnostic challenges of NAFLD in T1D, explore the link between IR and NAFLD and chronic complications, and examine the independent contribution of NAFLD to the presence of macro-, and microvascular complications.

Non-alcoholic fatty liver disease-From the cardiologist perspective

Non-alcoholic fatty liver disease (NAFLD) includes a range of disorders characterized by excess accumulation of triglycerides within the liver. While simple steatosis may be clinically stable, non-alcoholic steatohepatitis (NASH) can be progressive. Inflammation is believed to be the driving force behind NASH and the progression to fibrosis and subsequent cirrhosis. NAFLD is globally considered a significant health concern not only because of its incidence but also because of its economic impact. The fact that NAFLD is associated with cardiovascular disease is widely recognized, as well as the fact that NAFLD patient mortality rises when such an association is present. In particular, NAFLD is associated with coronary and carotid atherosclerosis, endothelial dysfunction and arterial rigidity, ventricles function, valves morphology, congestive heart failure, and arrhythmias (especially atrial fibrillation). Additionally, the hypercoagulability status in NAFLD patient may be suggested by the presence of inflammatory and coagulation markers. In order to differentiate between milder forms and the more severe ones that necessitate aggressive therapy, individualized risk scores may be used. This narrative review will analyze and interpret the papers published in PubMed in the last 16 years, in an attempt to expand our understanding of the NASH as a possible cardiovascular risk factor.

Protective effect of ursodeoxycholic acid, resveratrol, and N-acetylcysteine on nonalcoholic fatty liver disease in rats

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Resveratrol (RSV) and N-acetylcysteine (NAC) are safe representatives of natural and synthetic antioxidants, respectively.

OBJECTIVE

The objective of this study was to evaluate protective effects of RSV and NAC, compared with ursodeoxycholic acid (UDCA), on experimental NAFLD.

MATERIALS AND METHODS

NAFLD was induced by feeding rats a methionine choline-deficient diet (MCDD) for four cycles, each of 4 d of MCDD feeding and 3 d of fasting. Animals were divided into normal control, steatosis control, and five treatment groups, receiving UDCA (25 mg/kg/d), RSV (10 mg/kg/d), NAC (20 mg/kg/d), UDCA + RSV, and UDCA + NAC orally for 28 d. Liver integrity markers (liver index and serum transaminases), serum tumor necrosis factor-α (TNF-α), glucose, albumin, renal functions (urea, creatinine), lipid profile (total cholesterol; TC, triglycerides, high density lipoproteins, low density lipoproteins; LDL-C, very low density lipoproteins, leptin), and oxidative stress markers (hepatic malondialdehyde; MDA, glutathione; GSH, glutathione-S-transferase; GST) were measured using automatic analyzer, colorimetric kits, and ELISA kits, supported by a liver histopathological study.

RESULTS

RSV and NAC administration significantly improved liver index (RSV only), alanine transaminase (52, 52%), TNF-α (70, 70%), glucose (69, 80%), albumin (122, 114%), MDA (55, 63%), GSH (160, 152%), GST (84, 84%), TC (86, 86%), LDL-C (83, 81%), and leptin (59, 70%) levels compared with steatosis control values. A combination of RSV or NAC with UDCA seems to ameliorate their effects.

DISCUSSION AND CONCLUSION

RSV and NAC are effective on NAFLD through antioxidant, anti-inflammatory, and lipid-lowering potentials, where as RSV seems better than UDCA or NAC.

Nonalcoholic Fatty Liver Disease is Associated with Increased Carotid Intima-Media Thickness in Type 1 Diabetic Patients

A growing body of evidence suggests that NAFLD is associated with an increased risk of incident CVD events both in patients without diabetes and in those with type 2 diabetes (T2DM). However, no published data are available regarding the association between NAFLD and C-IMT in T1DM. A total of 722 patients (371 men) with T1DM were included in this cross-sectional study. The main outcome measures were detection of NAFLD, C-IMT and classical risk factors. The mean age of the subjects was 46.2 years, and 51.1% were male. The prevalence of NAFLD was 15.9%. NAFLD patients had a markedly greater C-IMT (0.81 ± 0.25 vs. 0.69 ± 0.18 mm; p < 0.001) and frequency of carotid plaque (28.9% vs. 16.9%; p < 0.05) than those without fatty liver. Moreover, the differences in C-IMT remained after adjusting for potential confounders. A stepwise linear regression analysis revealed that age (standardized β, 0.326; p < 0.001), NAFLD (standardized β, 0.151, p < 0.001), and hsCRP (standardized β, 0.115, p = 0.008) were independently associated with C-IMT in all subjects. Our data show NAFLD is associated with elevated C-IMT in T1DM independent of conventional cardiovascular disease risk factors.

Identification of novel clinical factors associated with hepatic fat accumulation in extreme obesity

OBJECTIVES

The accumulation of lipids stored as excess triglycerides in the liver (steatosis) is highly prevalent in obesity and has been associated with several clinical characteristics, but most studies have been based on relatively small sample sizes using a limited set of variables. We sought to identify clinical factors associated with liver fat accumulation in a large cohort of patients with extreme obesity.

METHODS

We analyzed 2929 patients undergoing intraoperative liver biopsy during a primary bariatric surgery. Univariate and multivariate regression modeling was used to identify associations with over 200 clinical variables with the presence of any fat in the liver and with moderate to severe versus mild fat accumulation.

RESULTS

A total of 19 data elements were associated with the presence of liver fat and 11 with severity of liver fat including ALT and AST, plasma lipid, glucose, and iron metabolism variables, several medications and laboratory measures, and sleep apnea. The accuracy of a multiple logistic regression model for presence of liver fat was 81% and for severity of liver fat accumulation was 77%.

CONCLUSIONS

A limited set of clinical factors can be used to model hepatic fat accumulation with moderate accuracy and may provide potential mechanistic insights in the setting of extreme obesity.