Adipocytokine polymorphisms and nonalcoholic fatty liver disease

Prevalence and risk factors for non-alcoholic fatty liver disease in Asian people who are not obese

Fatty liver (hepatic steatosis) is prevalent in industrialized countries. It is typically linked to obesity, central obesity and the presence of metabolic syndrome. With the introduction of a Westernized lifestyle and the increasing frequency of obesity in the Asia-Pacific region, the prevalence of non-alcoholic fatty liver disease (NAFLD) has been increasing over the past two decades. The risk factors are similar to those in other ethnic populations; but it is important to adopt the regional (ethnic-specific) anthropometric criteria to define overweight, obesity (including central obesity) and metabolic syndrome. To be noted, even using strict ethnic-specific criteria, a high percentage (15-21%) of Asia-Pacific NAFLD subjects in some series have been found to be non-obese, i.e. to have a normal body mass index (BMI) (17.5-22.4 kg/m(2)) or to be overweight (BMI 22.5-24.9 kg/m(2)). Differential distribution of visceral adipose tissue, recent increase in body weight, intake of high cholesterol diet and genetic background are factors likely associated with the development of NAFLD in these non-obese (but often overweight) Asia-Pacific subjects. Furthermore, insulin resistance may be the underlying key mechanism. In addition, since NAFLD may be the hepatic manifestation of metabolic syndrome, the presence of NAFLD is a predictor of future type 2 diabetes, metabolic syndrome and cardiovascular disease. Therefore, interventions at the public health level are indicated to halt the trend of overweight as well as obesity in Asia-Pacific region, particularly among those with relevant family history. Since the pathophysiology of NAFLD is closely related to metabolic derangement, lifestyle modification remains the cornerstone of management.

Bifidobacterium longum with fructo-oligosaccharides in patients with non alcoholic steatohepatitis

BACKGROUND

Increased exposure to intestinal bacterial products may contribute to the pathogenesis of non alcoholic steatohepatitis (NASH). Bifidobacteria are predominant bacterial species in the human gut microbiota and have been considered to exert a beneficial effect on human health by maintaining the equilibrium of the resident microbiota.

AIMS

To evaluate the effects of Bifidobacterium longum with fructo-oligosaccharides (Fos) in the treatment of NASH.

METHODS

A total of 66 patients were randomly and equally divided into two groups receiving Bifidobacterium longum with Fos and lifestyle modification (i.e., diet and exercise) versus lifestyle modification alone. The following variables were assessed at -4 (beginning of the dietary lead-in period), 0 (randomization), 6, 12, 18, and 24 weeks: aspartate transaminase (AST), alanine transaminase (ALT), bilirubin, albumin, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, fasting plasma glucose, insulin, C-peptide, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, homeostasis model assessment of insulin resistance (HOMA-IR), and serum endotoxins. Liver biopsies were performed at entry and repeated after 24 weeks of treatment.

RESULTS

At the end of study period, we observed that the Bifidobacterium longum with Fos and lifestyle modification group versus the lifestyle modification alone group showed significant differences in the AST -69.6 versus -45.9 IU/mL (P < 0.05), LDL cholesterol -0.84 versus -0.18 mmol/L (P < 0.001), CRP -2.9 versus -0.7 mg/L (P < 0.05), TNF-α -0.45 versus -0.12 ng/mL (P < 0.001), HOMA-IR -1.1 versus -0.6 (P < 0.001), serum endotoxin -45.2 versus -30.6 pg/mL (P < 0.001), steatosis (P < 0.05), and the NASH activity index (P < 0.05).

CONCLUSIONS

Bifidobacterium longum with Fos and lifestyle modification, when compared to lifestyle modification alone, significantly reduces TNF-α, CRP, serum AST levels, HOMA-IR, serum endotoxin, steatosis, and the NASH activity index.

Nonalcoholic fatty liver in Asia: Firmly entrenched and rapidly gaining ground

Nonalcoholic fatty liver disease (NAFLD) is becoming an important chronic liver disorder in Asia. Prevalence figures show regional variations but at least 10% of the general population in Asia have fatty liver. Fatty liver can develop with relatively small changes in weight (2-3 kg), often with increasing central adiposity. The metabolic syndrome may precede or follow NAFLD. Overt diabetes is present in one-third of cases but when oral glucose tolerance tests are performed, a further third of individuals have impaired glucose tolerance or diabetes. Natural history data are still scarce but cases of advanced hepatic fibrosis and hepatocellular carcinoma are now regularly reported. Many cases of cryptogenic cirrhosis are also attributable to NAFLD. Histological progression has been demonstrated for patients with NASH as well as for those with hepatic steatosis alone. Genetic factors may in part contribute to the rise in NAFLD. Polymorphisms within apolipoprotein C3 (APOC3) gene have been linked to NAFLD in lean Indian men. Although a number of other polymorphisms involving genes controlling adipose distribution, insulin signalling, adipokine responses and hepatic fibrosis have been reported, these studies have been underpowered. Transient elastography could help in detecting and monitoring hepatic fibrosis but further refinements in technique are necessary for obese individuals. Of the biomarkers, hyaluronic acid and cytokeratin-18 fragment testing show promise as markers of hepatic fibrosis and NASH, respectively. Lifestyle alterations including dietary changes and increased physical activity remain the cornerstone of management. Attention should be paid to prevention through public education of campaigns addressing the increase in both adult and childhood obesity.

A fresh look at NASH pathogenesis. Part 1: the metabolic movers

The strong relationship between over-nutrition, central obesity, insulin resistance/metabolic syndrome and non-alcoholic fatty liver disease (NAFLD) suggest pathogenic interactions, but key questions remain. NAFLD starts with over-nutrition, imbalance between energy input and output for which the roles of genetic predisposition and environmental factors (diet, physical activity) are being redefined. Regulation of energy balance operates at both central nervous system and peripheral sites, including adipose and liver. For example, the endocannabinoid system could potentially be modulated to provide effective pharmacotherapy of NAFLD. The more profound the metabolic abnormalities complicating over-nutrition (glucose intolerance, hypoadiponectinemia, metabolic syndrome), the more likely is NAFLD to take on its progressive guise of non-alcoholic steatohepatitis (NASH). Interactions between steatosis and insulin resistance, visceral adipose expansion and subcutaneous adipose failure (with insulin resistance, inflammation and hypoadiponectinemia) trigger amplifying mechanisms for liver disease. Thus, transition from simple steatosis to NASH could be explained by unmitigated hepatic lipid partitioning with failure of local adaptive mechanisms leading to lipotoxicity. In part one of this review, we discuss newer concepts of appetite and metabolic regulation, bodily lipid distribution, hepatic lipid turnover, insulin resistance and adipose failure affecting adiponectin secretion. We review evidence that NASH only occurs when over-nutrition is complicated by insulin resistance and a highly disordered metabolic milieu, the same 'metabolic movers' that promote type 2 diabetes and atheromatous cardiovascular disease. The net effect is accumulation of lipid molecules in the liver. Which lipids and how they cause injury, inflammation and fibrosis will be discussed in part two.

The liver and the waistline: Fifty years of growth

Fifty years of the Gastroenterological Society of Australia have witnessed the changing appearance of Australians. Asian immigration has transformed the dominant urban culture from European to Eurasian, with some unique Australian attributes. Meanwhile, global conditions have altered body shape, and our sports-proud country is now fat! Thus, as in North America, Europe, China, and affluent Asia-Pacific countries, prosperity and lifestyle, cheap processed foods coupled with reduced physical activity have created an epidemic of over-nutrition resulting in overweight/obesity. Additional genetic factors are at the core of the apple shape (central obesity) that typifies over-nourished persons with metabolic syndrome. Indigenous Australians, once the leanest and fittest humans, now have exceedingly high rates of obesity and type 2 diabetes, contributing to shorter life expectancy; Asian Australians are also at higher risk. Like non-steroidal anti-inflammatory drugs (NSAIDs) and cigarette smoking, obesity now contributes much to gastrointestinal morbidity and mortality (gastroesophageal reflux disease, cancers, gallstones, endoscopy complications). This review focuses on Australian research about fatty liver, particularly roles of central obesity/insulin resistance in non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH). The outputs include many highly cited original articles and reviews and the first book on NAFLD. Studies have identified community prevalence, clinical outcomes, association with insulin resistance, metabolic syndrome and hypoadiponectinemia, developed and explored animal models for mechanisms of inflammation and fibrosis, conceptualized etiopathogenesis, and demonstrated that NASH can be reversed by lowering body weight and increasing physical activity. The findings have led to development of regional guidelines on NAFLD, the first internationally, and should now inform daily practice of gastroenterologists.