Role of Oxidative Stress and Lipid Peroxidation in the Pathophysiology of NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is characterised by an excess of hepatic fat that can progress to steatohepatitis, fibrosis, cirrhosis and hepatocarcinoma. The imbalance between lipid uptake/lipogenesis and lipid oxidation/secretion in the liver is a major feature of NAFLD. Given the lack of a non-invasive and reliable methods for the diagnosis of non-alcoholic steatohepatitis (NASH), it is important to find serum markers that are capable of discriminating or defining patients with this stage of NASH. Blood samples were obtained from 152 Caucasian subjects with biopsy-proven NAFLD due to persistently elevated liver enzyme levels. Metabolites representative of oxidative stress were assessed. The findings derived from this work revealed that NAFLD patients with a NASH score of ≥ 4 showed significantly higher levels of lipid peroxidation (LPO). Indeed, LPO levels above the optimal operating point (OOP) of 315.39 µM are an independent risk factor for presenting a NASH score of ≥ 4 (OR: 4.71; 95% CI: 1.68−13.19; p = 0.003). The area under the curve (AUC = 0.81, 95% CI = 0.73−0.89, p < 0.001) shows a good discrimination ability of the model. Therefore, understanding the molecular mechanisms underlying the basal inflammation present in these patients is postulated as a possible source of biomarkers and therapeutic targets in NASH.

Insulin resistance is related with liver fibrosis in type 2 diabetic patients with non-alcoholic fatty liver disease proven biopsy and Mediterranean diet pattern as a protective factor.

BACKGROUND AND AIMS: The prevalence of the non-alcoholic fatty liver disease (NAFLD) in developed countries is up to 30% of the general population, and 50% of patients present type 2 diabetes mellitus (DM2). Fibrosis is the most important prognostic factor in NAFLD. The aim of this study was to search evidence for an early diagnosis of liver fibrosis in subjects with DM2 and to evaluate potential risk and protective factors. METHODS: This study was conducted among 160 diabetic patients with NAFLD proven biopsy. Anthropometric assessments, laboratory test, liver histological features and follow-up of a Mediterranean diet were evaluated. RESULTS: Diabetic patients with liver fibrosis showed a greater number of positive metabolic criteria than diabetic patients without liver fibrosis. Patients with hepatic fibrosis have a lower score on the PREDIMED test (9.0 (2.4) vs. 6.2 (2.3); p < 0.05). Diabetic patients with liver fibrosis showed higher glucose levels (delta: 10.1 (4.5) mg/dl), fasting insulin levels (delta: 3.1 (1.5) UI/L), HOMA-IR (delta: 2.1 (0.3) units) and HbA1c (delta: 0.6 (0.2)%). Non-invasive tests showed a higher score (non-alcoholic fatty liver disease fibrosis score and fibrosis-4) in liver fibrosis subjects than no liver fibrosis subjects. A logistic regression analysis adjusted by age, gender, HbA1c and body mass index showed independent significant direct association between liver fibrosis and homeostatic model assessment of insulin resistance as indicator of insulin resistance (odds ratio (OR) = 1.53: 95% confidence interval (CI): 1.1-2.2; p = 0.026) and inverse association with PREDIMED score as an indicator of adherence to Mediterranean diet (OR = 0.6; 95% CI: 0.4-0.8; p = 0.01). CONCLUSION: In patients with DM2, insulin resistance is an independent risk factor associated with liver fibrosis, and the adherence of a Mediterranean diet is a protective factor associated with absence of liver fibrosis.

Comparative study of overweight and obese patients with nonalcoholic fatty liver disease.

BACKGROUND AND AIMS: non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder in the western world. Although NAFLD prevalence is higher in patients with a BMI > 25 kg /m2, it is unclear if there are differences between overweight and obese patients. The associated biochemical, dietary and genetic parameters were compared between overweight and obese patients with NAFLD. METHODS: patients with biopsy-proven NAFLD (n = 203) were enrolled in a cross-sectional study. The MEDAS questionnaire was used to assess adherence to the Mediterranean diet. Biochemical, anthropometrical parameters and the I148M variant (rs738409) of the PNPLA3 gene and rs180069 of the TNF-α gene were evaluated. RESULTS: overweight patients had higher serum adiponectin levels (22.5 ± 21.9 vs 11.2 ± 18.1 ng/ml; p < 0.05) and lower resistin (3.3 ± 1.7 vs 8.1 ± 8 ng/ml; p < 0.001) and leptin concentrations (22.9 ± 21.9 vs 55.8 ± 45 ng/ml; p < 0.001) than obese patients. Non-alcoholic steatohepatitis (NASH) was more frequent in the obese group (59.3% vs 41.3%; p = 0.02). The multivariate analysis showed adherence to the Mediterranean diet to be an independent protective factor for NASH and liver fibrosis in overweight patients (OR 0.7, 95% CI 0.5-0.8). CONCLUSIONS: NASH was more prevalent in obese patients than in overweight subjects. HOMA-IR and adherence to the Mediterranean diet provided protection against fibrosis in overweight patients. Adherence to the Mediterranean diet was the only independent factor associated with NASH in these patients.

Role of the PNPLA3 polymorphism rs738409 on silymarin + vitamin E response in subjects with non-alcoholic fatty liver disease.

BACKGROUND: non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in developed countries. Lifestyle changes are the pillar of the treatment, although a pharmacological approach is sometimes required in the case of a failure to respond/adhere to the diet. OBJECTIVE: the aim of this study was to evaluate the effect of silymarin and the influence of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) variant on the response to treatment in patients with NAFLD in a pilot study. METHODS: a total of 54 patients with a NAFLD proven biopsy were enrolled in an open prospective study and were treated with Eurosil 85® (silymarin + vitamin E) for six months. Biochemical parameters and cardiovascular risk factors (diabetes mellitus, dyslipidemia, hypertriglyceridemia, arterial hypertension and HOMA-IR > 2.5) were recorded before and after six months of treatment. Non-invasive indexes (fatty liver index, lipid accumulation product and NAFLD-fibrosis score) were also calculated. The rs738409 PNPLA3 gene polymorphism status was also determined. RESULTS: significant statistical changes from baseline values after six months of treatment were observed in transaminases levels but not in non-invasive index markers. Twenty patients (37.1%) were G allele carriers and had a higher percentage of lobular inflammation and ballooning on the basal liver biopsy. Patients with the G allele had a smaller decrease in transaminases levels after treatment with silymarin + vitamin E than non-G-allele carriers. CONCLUSIONS: treatment with silymarin + vitamin E produced a decrease in transaminases after six months of treatment without an accompanying weight loss. PNPLA3 G-allele carriers responded poorly to the treatment.