Necessity for timely noninvasive diagnosis of nonalcoholic fatty liver disease

Circulating leptin in non-alcoholic fatty liver disease: a systematic review and meta-analysis

AIMS/HYPOTHESIS

Clinical data regarding circulating leptin levels in patients with non-alcoholic fatty liver disease (NAFLD) are conflicting. The purpose of this meta-analysis was to compare leptin levels between the following groups: patients with biopsy-proven NAFLD vs controls; simple steatosis (SS) patients vs controls; non-alcoholic steatohepatitis (NASH) patients vs controls and NASH patients vs SS patients.

METHODS

We performed a systematic search in PubMed, Scopus and the Cochrane Library. We analysed 33 studies, published between 1999 and 2014, including 2,612 individuals (775 controls and 1,837 NAFLD patients).

RESULTS

Higher circulating leptin levels were observed in NAFLD patients vs controls (standardised mean difference [SMD] 0.640; 95% CI 0.422, 0.858), SS patients vs controls (SMD 0.358; 95% CI 0.043, 0.673), NASH patients vs controls (SMD 0.617; 95% CI 0.403, 0.832) and NASH patients vs SS patients (SMD 0.209; 95% CI 0.023, 0.395). These results remained essentially unchanged after excluding studies involving paediatric or adolescent populations and/or individuals undergoing bariatric surgery. There was moderate-to-severe heterogeneity among studies in all comparisons, but no significant publication bias was detected. Meta-regression analysis demonstrated that BMI was inversely associated with leptin SMD and accounted for 26.5% (p = 0.014) and 32.7% (p = 0.021) of the between-study variance in the comparison between NASH patients and controls and NAFLD patients and controls, respectively. However, when bariatric studies were excluded, BMI did not significantly explain the between-study variance.

CONCLUSIONS/INTERPRETATION

Circulating leptin levels were higher in patients with NAFLD than in controls. Higher levels of circulating leptin were associated with increased severity of NAFLD, and the association remained significant after the exclusion of studies involving paediatric or adolescent populations and morbidly obese individuals subjected to bariatric surgery.

Nonalcoholic fatty liver disease and hepatic cirrhosis: Comparison with viral hepatitis-associated steatosis

Nonalcoholic fatty liver disease (NAFLD) including nonalcoholic steatohepatitis (NASH) is globally increasing and has become a world-wide health problem. Chronic infection with hepatitis B virus or hepatitis C virus (HCV) is associated with hepatic steatosis. Viral hepatitis-associated hepatic steatosis is often caused by metabolic syndrome including obesity, type 2 diabetes mellitus and/or dyslipidemia. It has been reported that HCV genotype 3 exerts direct metabolic effects that lead to hepatic steatosis. In this review, the differences between NAFLD/NASH and viral hepatitis-associated steatosis are discussed.

Non-alcoholic fatty liver disease associated with increased arterial stiffness in subjects with normal glucose tolerance, but not pre-diabetes and diabetes

AIM

To evaluate the association between non-alcoholic fatty liver disease and arterial stiffness in adults with normal glucose tolerance, pre-diabetes and newly diagnosed diabetes after excluding known diabetes.

METHODS

A total of 4860 subjects were divided into normal glucose tolerance, pre-diabetes and newly diagnosed diabetes groups according to the American Diabetes Association 2011 diagnostic criteria. The severity of non-alcoholic fatty liver disease was divided into mild and moderate to severe. Increased arterial stiffness was defined as brachial-ankle pulse wave velocity (baPWV) ⩾ 1400 cm/s.

RESULTS

There was a significant difference in the prevalence of mild and moderate to severe non-alcoholic fatty liver disease between subjects with and without increased arterial stiffness. Mild (odds ratio (OR) = 2.02, 95% confidence interval (CI) = 1.43-2.84) and moderate to severe (OR = 2.15, 95% CI = 1.33-3.46) non-alcoholic fatty liver disease were independently associated with increased arterial stiffness in the normal glucose tolerance group. In the pre-diabetes and diabetes groups, neither mild nor moderate to severe non-alcoholic fatty liver disease was associated with increased arterial stiffness.

CONCLUSION

The effect of non-alcoholic fatty liver disease on arterial stiffness is apparent in subjects with normal glucose tolerance, but not in diabetes and pre-diabetes.

Importance of imaging and recent developments in diagnosis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease and is a major public health problem worldwide. It is a spectrum that includes simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis. Recently, NAFLD prevalence in children and adolescents has increased too. The increasing prevalence has resulted in NASH-related chronic liver disease. Therefore, early diagnosis and treatment is quite important. Although liver biopsy is still the gold standard for diagnosis and staging of NAFLD, particularly for the diagnosis of NASH, imaging methods such as ultrasonography, computed tomography, magnetic resonance imaging with chemical shift imaging and especially magnetic resonance spectroscopy and elastography have been increasingly approved as noninvasive alternative methods. The aim of this review is to analyze the diagnostic accuracy and limitations of the imaging methods and recent developments in the diagnosis of NAFLD.

EFFECT OF HELICOBACTER PYLORI ERADICATION ON HEPATIC STEATOSIS, NAFLD FIBROSIS SCORE AND HSENSI IN PATIENTS WITH NONALCOHOLIC STEATOHEPATITIS: a MR imaging-based pilot open-label study

Context Limited clinical data suggest Helicobacter pylori (Hp) infection may contribute to nonalcoholic fatty liver disease (NAFLD) pathogenesis. Objectives The effect of Hp eradication on hepatic steatosis (magnetic resonance imaging), nonalcoholic fatty liver disease fibrosis score and HSENSI (Homocysteine, serum glutamic oxaloacetic transaminase, Erythrocyte sedimentation rate, nonalcoholic steatohepatitis Index) in nonalcoholic steatohepatitis patients. Methods Thirteen adult patients with biopsy-proven nonalcoholic steatohepatitis, asymptomatic for gastrointestinal disease, underwent 13C urea breath test; Hp positive patients received eradication therapy until repeat test become negative. Hepatic fat fraction, standard biochemical tests and calculation of nonalcoholic fatty liver disease fibrosis score and HSENSI were performed at baseline and month 12. Results Hepatic fat fraction was similar for between and within group comparisons. Nonalcoholic fatty liver disease fibrosis score showed a non-significant trend towards decrease in Hp(+) [-0.34 (-1.39-0.29) at baseline and -0.24 (-0.99-0.71) at month 12; P = 0.116], whereas increase in Hp(-) group [-0.38 (-1.72-0.11) and -0.56 (-1.43-0.46), respectively; P = 0.249]. HSENSI was significantly decreased only in Hp(+) group [1.0 (1.0-2.0) at baseline and 1.0 (0-1.0) at month 12; P = 0.048]. Conclusions Hp eradication had no long-term effect on hepatic steatosis, but showed a trend towards improvement in nonalcoholic fatty liver disease fibrosis score and HSENSI. These results warrant larger studies with paired biopsies.

Moderate to severe, but not mild, nonalcoholic fatty liver disease associated with increased risk of gallstone disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) and gallstone disease (GSD) share some of the same risk factors. The association between NAFLD and GSD was inconsistent. Moreover, there are no studies on the association between GSD and the severity of NAFLD in the literature. The aim of this study was to determine the relationship between the severity of NAFLD and GSD in a Taiwanese population.

MATERIALS AND METHODS

A total of 12,033 subjects were enrolled. The diagnoses of GSD and NAFLD were based on the finding of abdominal ultrasonography. The severity of NAFLD was divided into mild, moderate, and severe.

RESULTS

Compared with the non-GSD group, the GSD one was older and had a higher BMI, blood pressure, fasting plasma glucose, cholesterol, triglyceride, and higher prevalence of diabetes and hypertension, but they had a lower eGFR and HDL-C level and less prevalence of current smoking and alcohol drinking. There was a significant difference in the severity of NAFLD between subjects with and without GSD. Based on logistic regression, age ≥65 versus <40 years, 40-64.9 versus <40 years, female, current alcohol drinking, diabetes, hypertension, HDL-C level and moderate to severe NAFLD, but not mild NAFLD, were the independently associated risk factors of GSD.

CONCLUSION

Moderate to severe, but not mild, NAFLD was associated with an increased risk of GSD, independent of the traditional cardio-metabolic risk factor. Age, female, diabetes, and hypertension were also related to a higher risk of GSD, but HDL-C level and moderate alcohol drinking showed a lower risk.

De novo lipogenesis in health and disease

BACKGROUND

De novo lipogenesis (DNL) is a complex and highly regulated metabolic pathway. In normal conditions DNL converts excess carbohydrate into fatty acids that are then esterified to storage triacylglycerols (TGs). These TGs could later provide energy via β-oxidation. In human body this pathway is primarily active in liver and adipose tissue. However, it is considered to be a minor contributor to the serum lipid homeostasis. Deregulations in the lipogenic pathway are associated with diverse pathological conditions.

SCOPE OF REVIEW

The present review focuses on our current understanding of the lipogenic pathway with special reference to the causes and consequences of aberrant DNL.

MAJOR CONCLUSIONS

The deregulation of DNL in the major lipogenic tissues of the human body is often observed in various metabolic anomalies - including obesity, non-alcoholic fatty liver disease and metabolic syndrome. In addition to that de novo lipogenesis is reported to be exacerbated in cancer tissues, virus infected cells etc. These observations suggest that inhibitors of the DNL pathway might serve as therapeutically significant compounds. The effectiveness of these inhibitors in treatment of cancer and obesity has been suggested by previous works.

GENERAL SIGNIFICANCE

De novo lipogenesis - which is an intricate and highly regulated pathway - can lead to adverse metabolic consequences when deregulated. Therapeutic targeting of this pathway may open a new window of opportunity for combating various lipogenesis-driven pathological conditions - including obesity, cancer and certain viral infections.