Prevalence of fatty liver disease and its risk factors in the population of South China

miR-18a-5p/PXR/SREBP2 Was Involved in MAFLD Associated With Methyl Tert-Butyl Ether Among Petrol Station Workers

BACKGROUND

Metabolic associated fatty liver disease (MAFLD), previously defined as non-alcoholic fatty liver disease (NAFLD), has been shown to be closely related to many environmental pollutants. Lately, we found methyl tert-butyl ether (MTBE), a new environmental pollutant, could increase NAFLD risk in American adults, which still needs more population epidemiological studies to verify, and its pathogenic mechanism is not yet clear.

METHODS

We conducted a cross-sectional study among petrol station workers, diagnosed their MAFLD according to internationally recognised diagnostic criteria, assessed the potential association of MTBE exposure with MAFLD risk, and explored the miR-18a-5p/PXR/SREBP2 pathway as possible pathogenic mechanisms in male Wistar rats and HepaRG cells treated with MTBE.

RESULTS

Blood MTBE levels were found to be significantly correlated with an increased risk of MAFLD, and MAFLD risk increased by 24.3% for every 0.1 μg/L increase in blood MTBE. Consistently, we found that MTBE exposure could induce MAFLD in rats and HepaRG cells, and activate pregnane X receptor (PXR) by inhibiting miR-18a-5p to upregulate the expression of sterol regulatory element-binding protein 2 (SREBP2) and its nuclear translocation, thereby upregulating the expression of its downstream target genes.

CONCLUSIONS

Our study demonstrated that MTBE exposure might be a significant risk factor for MAFLD, and MTBE could promote liver cholesterol synthesis and lipid deposition by activating the miRNA-18a-5p/PXR/SREBP2 pathway.

Epigenetic mechanisms underlying the link between non-alcoholic fatty liver diseases and nutrition

Non-alcoholic fatty liver disease (NAFLD) is defined as a pathologic accumulation of fat in the form of triglycerides (TG) in the liver (steatosis) that is not caused by alcohol. A subgroup of NAFLD patients shows liver cell injury and inflammation coupled with the excessive fat accumulation (steatohepatitis), which is referred to as non-alcoholic steatohepatitis (NASH). Patients with NASH may develop cirrhosis and hepatocellular carcinoma (HCC). NAFLD shares the key features of metabolic syndrome including obesity, hyperlipidemia, hypertension, and insulin resistance. The pathogenesis of NAFLD is multi-factorial, however the oxidative stress seems to plays a major role in the development and progression of the disease. The emerging field of epigenetics provides a new perspective on the pathogenesis of NAFLD. Epigenetics is an inheritable but reversible phenomenon that affects gene expression without altering the DNA sequence and refers to DNA methylation, histone modifications and microRNAs. Epigenetic manipulation through metabolic pathways such as one-carbon metabolism has been proposed as a promising approach to retard the progression of NAFLD. Investigating the epigenetic modifiers in NAFLD may also lead to the development of preventive or therapeutic strategies for NASH-associated complications.

The effect of miRNA-122 in regulating fat deposition in a cell line model

Accumulating evidence supports the role of miR-122 in fatty liver disease. We investigated miR-122 expression in a steatotic hepatocyte model, the effect of miR-122 over-expression and inhibition in the pathogenesis. Human hepatic cell line L02 was induced with oleic acid to establish the steatotic hepatocyte model. Intracellular lipid content was observed with laser scanning confocal microscope (LSCM), and triglyceride content was determined with kits. Total RNA was extracted and reversely transcribed into cDNA. miR-122 expression was measured using qRT-PCR. Subsequently, miR-122 mimic and miR-122 inhibitor were transfected into steatotic hepatocytes to observe their effect on intracellular lipid content. The lipid fluorescence intensity and triglyceride content within the steatotic hepatocytes were significantly higher than those in normal control (860.01 ± 26.52 vs. 257.77 ± 29.69 and 3.47 ± 0.12 vs. 1.85 ± 0.02 at 24 h) (P < 0.01). miR-122 expression in steatotic hepatocytes was down-regulated compared with that in control (2-ΔCt value: 0.0286 ± 0.0078 vs. 0.0075 ± 0.0012) (P ≪ 0.01). After transfection, miR-122 expression (2-ΔCt value) in the miR-122 mimic group increased 2.96-fold compared with that in control, and its lipid fluorescence intensity was significantly lower than that in control (790.92 ± 46.72 vs. 1,022.16 ± 49.66) (P < 0.01). Nevertheless, miR-122 expression decreased 3.45-fold in the miR-122 inhibitor group compared with that in control, and its fluorescence intensity was significantly higher than that in control (1,386.49 ± 40.34 vs 1,022.16 ± 49.66)(P ≪ 0.01). We concluded that miR-122 was down-regulated in steatotic hepatocytes model. The pathogenesis of hepatocyte steatosis was enhanced by miR-122 mimic and reduced with miR-122 inhibitor.

Epidemiology and risk factors of nonalcoholic fatty liver disease (NAFLD)

The nonalcoholic fatty liver disease (NAFLD) is defined as the presence of hepatic steatosis, determined by either imaging or histology, in the absence of secondary causes of hepatic fat accumulation. Nonalcoholic fatty liver is defined as the presence of hepatic steatosis with no evidence of hepatocellular injury in the form of ballooning of the hepatocytes or fibrosis. NASH is defined as the presence of hepatic steatosis and inflammation with hepatocyte injury (ballooning) with or without fibrosis. Although initial epidemiological studies have focused on its prevalence in the Western countries, it is becoming increasingly clear that NAFLD is highly prevalent in the Asia Pacific region, and there may be important distinctions in its phenotype between Asia Pacific and Western countries. Of particular interest are "lean NAFLD" and the "urban-rural divide," which will be discussed in this review article. Obesity, dyslipidemia, type 2 diabetes and metabolic syndrome are established risk factors for developing NAFLD. Many other risk factors (e.g., hypothyroidism, polycystic ovary syndrome, obstructive sleep apnea, hypopituitarism and hypogonadism) for NAFLD have been described in the Western countries, but these associations are yet to be investigated adequately in the Asia Pacific region.

Cyclooxygenase-2 promotes hepatocellular apoptosis by interacting with TNF-α and IL-6 in the pathogenesis of nonalcoholic steatohepatitis in rats

BACKGROUND AND PURPOSE

The underlying mechanisms of nonalcoholic steatohepatitis (NASH) are poorly understood, and little is known about hepatocellular apoptosis in NASH. Cyclooxygenase (COX)-2, the key enzyme in eicosanoid metabolism, is highly expressed in NASH. COX-2 can also regulate the release of mediators of inflammation, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6. The aim of our study was to evaluate the effects of COX-2 on hepatocellular apoptosis and the mechanism of the action in the pathogenesis of NASH in rats.

METHODS

Sprague-Dawley rats were fed a high-fat diet (HFD) or standard diet for 8 and 12 weeks. COX-2 and cytokines expression in hepatic tissue and TNF-α and IL-6 levels in serum were measured at 8 and 12 weeks. Moreover, celecoxib (10 mg/kg body weight once a day) was administered to rats for 4 weeks to inhibit the expression of COX-2. Liver pathology was assessed by hematoxylin and eosin (H&E) stain and electron microscopy. Hepatocyte apoptosis was evaluated by TUNEL staining.

RESULTS

COX-2 messenger RNA and protein were highly expressed in livers of HFD rats and were correlated with the severity of steatohepatitis (R = 0.82, p < 0.01). COX-2 upregulation was preceded by increases in TNF-α and IL-6. The level of hepatocellular apoptosis was significantly higher in HFD rats than in the control rats. The hepatocellular apoptosis was suppressed by the inhibition of COX-2.

CONCLUSIONS

COX-2 may promote hepatocellular apoptosis by interacting with TNF-α and IL-6 in NASH in rats.

Non alcoholic fatty liver disease in southern Iran: a population based study

BACKGROUND

Population based studies on prevalence and risk factors of NAFLD in Iranian population are few. The prevalence of NAFLD and non alcoholic steatohepatitis (NASH) in Iranians varies from 2.9% to 7.1% in general population and 55.8% in patients with type 2 diabetes mellitus.

OBJECTIVES

To determine the prevalence and determinants of non alcoholic fatty liver disease (NAFLD) in a sample of adult Iranian general population.

PATIENTS AND METHODS

This was a cross-sectional study being performed in Shiraz, southern Iran during a 10-month period from November 2010 to September 2011 through cluster random sampling of Iranian general population in Shiraz region. All individuals undergone anthropometric, blood pressure measurements, thorough medical history and physical examinations. Laboratory measurements included fasting blood glucose (FBS), lipid profile, complete blood count (CBC) and liver function tests. NAFLD was diagnosed by transabdominal ultrasonography.

RESULTS

819 subjects were included in this study among which were 340 males (41.5%) and 479 females (58.5%) with the mean age of 43.1 ± 14.1 years. NAFLD was diagnosed in 176 (21.5%) subjects. Patients with NAFLD were significantly older (P < 0.001), had higher proportion of male gender (P = 0.004) and had higher BMI (P < 0.001). They also had higher prevalence of hypertension (P < 0.001), high FBS (P < 0.001), high cholesterol (P = 0.026), high triglyceride (P < 0.001) and high waist circumference (P < 0.001). Taking all these together, patients with NAFLD had significantly higher prevalence of metabolic syndrome when compared to healthy subjects (P < 0.001).

CONCLUSION

The prevalence of NAFLD in this group of Iranian adult general population is 21.5%. NAFLD in Iranian population is associated with male gender, old age, obesity, and features of metabolic syndrome.

An epidemiological survey of prevalence of fatty liver disease in a general adult population in Shenyang

AIM: To investigate the prevalence of and major risk factors for fatty liver in adult residents in Shenyang.

METHODS: A total of 1 100 subjects who underwent physical examination in our center from August 2011 to November 2011 were included in this study. The survey included questionnaire investigation, physical examination, laboratory examination, and ultrasonic abdomen examination. The diagnosis of fatty liver disease was based on criteria adopted by the China Institute of Liver Disease and Alcoholic Liver Disease Group, and the prevalence of and major risk factors for fatty liver disease were investigated.

RESULTS: The prevalence of fatty liver in 1 100 detected cases was 41.64%. Males had a higher prevalence than females (45.15% vs 37.45%, χ² = 6.557, P < 0.05). Age between 41 and 50 years was the peak age for the development of the disease (47.92%), while the prevalence of fatty liver had a significantly increased trend in the age groups of 21-30 years and 31-40 years (33.33% and 46.25%). The difference in the prevalence of fatty liver disease between the city's different regions was not significant (χ² = 0.336, P > 0.05). There was a higher incidence of the disease in workers, civil servants, and general staff (χ² = 72.381, P < 0.05). The mean age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), uric acid (UA), triglycerides (TG), fasting-serum glucose level (GLUO), low-density lipoprotein cholesterol (LDL-C) and liver enzyme indicators (including γ-glutamyl transpeptidase, γ-GT, aspartate transaminase, (alanine aminotransferase and alkaline phosphatase) were significantly higher in the fatty liver group than in the group without fatty liver disease (χ² = 285.521, P < 0.001). The proportion of fatty liver was significantly increased with the increase in BMI. Logistic regression analysis demonstrated a close correlation between fatty liver disease and age, sex (male), BMI, SBP, DBP, UA, ApoB, LDL-C, TG and GLUO.

CONCLUSION: The prevalence of fatty liver disease was high, especially in middle-aged persons in Shenyang region. Age, sex, overweight or obesity, hypertension, glucose metabolism disorders, dyslipidemia and hyperuricemia were closely associated with the development of fatty liver disease.

Association of proinsulin and hepatic steatosis in a random, population-based sample

OBJECTIVE

Proinsulin may represent a predictive marker for assessing insulin resistance and reduced β-cell function. The objective of this study was to investigate the association between hepatic steatosis, proinsulin and other parameters in a random, population-based sample.

DESIGN

Cross-sectional study, conducted in south-western Germany.

METHODS

Upper abdominal ultrasound examinations were performed in 343 subjects (147 females, 196 males; average age 40.0±11.5 years). Proinsulin, the proinsulin-to-insulin ratio and other laboratory parameters were determined, and the BMI, waist-to-hip ratio (WHR) and other anthropometric data were documented.

RESULTS

HEPATIC STEATOSIS WAS OBSERVED IN 80 SUBJECTS (23.3%: 29.6%, males; 15.0%, females). Multivariate analysis showed an association with hepatic steatosis for male gender (P=0.0212), advancing age (P=0.0241), elevated BMI (P<0.0001), elevated WHR (P=0.0024), alanine aminotransferase (P=0.0046), proinsulin (P=0.0403) and proinsulin-to-insulin ratio (P=0.0116).

CONCLUSIONS

There is an association between elevated proinsulin concentrations and hepatic steatosis.

The relationship between pediatric nonalcoholic fatty liver disease and cardiovascular risk factors and increased risk of atherosclerosis in obese children

To investigate the relationship between nonalcoholic fatty liver disease and cardiovascular risk factors and increased risk of atherosclerosis in obese children. The study included 80 consecutive obese children who were stratified into group 1 [ultrasonographically diagnosed with NAFLD (n = 50)] and group 2 [not diagnosed with NAFLD (n = 30)]. The control group included 30 healthy children. The groups were compared in terms of clinical cardiovascular risk factors and carotid intimal medial thickness (CIMT) (as a marker of atherosclerosis) measured using B-mode ultrasound. Mean body mass index (BMI) and blood pressure (BP), as well as the frequency of dyslipidemia, metabolic syndrome (MetS), and insulin resistance (IR), were similar in groups 1 and 2. Mean BMI and triglyceride (TG) levels, and the frequency of IR and MetS, increased significantly as the grade of steatosis increased. Mean CIMT in group 1 was significantly greater than that in the control group (P < 0.01). There was a positive correlation between CIMT and age, BP, and BMI in groups 1 and 2. In addition, CIMT was correlated with TG, low high-density lipoprotein (HDL) cholesterol, MetS, and IR only in group 1. Linear regression analysis between CIMT and age, BP, BMI, TG level, HDL cholesterol level, IR, MetS, and grade of steatosis yielded a significant difference only for grade of steatosis. Cardiovascular risk factors are more impressive and CIMT was significantly higher in group 1 than in group 2 and the control group, indicating that they are associated with greater risk of atherosclerosis and future adverse cardiovascular events.

High ambulatory blood pressure values associated with non-alcoholic fatty liver in middle-aged adults

OBJECTIVE

Nonalcoholic fatty liver and hypertension are associated with metabolic syndrome. Both conditions increase the risk for cardiovascular morbidity. The objective of this study was to analyze whether 24-h blood pressure (BP) levels and nondipping phenomenon associate with hepatic steatosis defined as liver brightness.

METHODS

Twenty-four hour ambulatory BP measurement (ABPM) and liver brightness were investigated in a population-based cohort of 890 hypertensive (n = 433) and normotensive (n = 457) individuals aged 40-60 years. ABPM was recorded using the fully automatic SpaceLabs90207 oscillometric unit.

RESULTS

Fatty liver was associated with male sex, increased alcohol consumption, high BMI, large waist (P < 0.001 for all) and increased prevalence of smoking (P < 0.03). Values of alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), triglycerides and high-sensitivity CRP (hsCRP) were higher and high-density lipoprotein cholesterol lower (P < 0.001 for all) in individuals with fatty liver. After adjustments for BMI, sex and age, fatty liver was associated with 24-h (P < 0.005), daytime (P < 0.02) and night-time (P < 0.005) SBP measurements and DBP at daytime (P < 0.03). The association with nondipping showed only a trend (P = 0.057).

CONCLUSION

Significantly higher ambulatory daytime and night-time SBP levels were seen in individuals with fatty liver. Nondipping does not seem to associate with liver fat. The coexistence of liver fat accumulation and high BP are likely to potentiate the risk for cardiovascular disease.

1,25-dihydroxyvitamin D3 inhibits fibrosis in mice with NAFLD induced by a methionine-choline-deficient diet

AIM: To investigate whether 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active form of vitamin D, inhibits fibrosis induced by a methionine-choline-deficient (MCD) diet in C57BL/6J mice and to explore the possible mechanisms involved.

METHODS: Male C57BL/6J mice (n = 30) were divided randomly into control group, MCD group, and MCD + 1,25(OH)₂D₃ group. The MCD and MCD + 1,25(OH)₂D₃ groups were fed a MCD diet. All the mice were intraperitoneally injected with 1,25(OH)₂D₃ (5 μg/kg) or equal volume of saline twice weekly. After 8 wk, the mice were sacrificed to take serum samples for biochemical measurements and liver samples for HE staining and RT-PCR.

RESULTS: Serum levels of alanine aminotransferase, aspartate aminotransferase, and mRNA expression of transforming growth factor beta1 (TGF-β1), α-smooth muscle actin (α-SMA) and collagenⅠa1 of MCD group significantly increased in the MCD group compared to the control group (P = 0.000, 0.000, 0.044, 0.003, 0.027). In the MCD + 1,25(OH)₂D₃ group, all the above parameters significantly decreased (P = 0.000, 0.005, 0.020, 0.027) except the mRNA expression of TGF-β1, which showed no significant change, compared to the MCD group. Steatosis was significantly improved, as revealed by the presence of fewer lipid drops in the cytoplasm and less inflammatory cell infiltration around the vessels, in the MCD + 1,25(OH)₂D₃ group compared to the MCD group.

CONCLUSION: 1,25(OH)₂D₃ can improve liver function and inhibit fibrosis possibly by down-regulating the mRNA expression of α-SMA and collagenⅠa1 in mice with NAFLD induced by a MCD diet.

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.

Lifestyle intervention in non-alcoholic fatty liver disease in Chengyang District, Qingdao, China

AIM

To evaluate the effect of a 6 and 12 mo lifestyle modification intervention in nonalcoholic fatty liver diseases (NAFLD) in Chengyang District of Qingdao.

METHODS

Participants with NAFLD who had resided in Chengyang District for more than 5 years were enrolled in this study. After the 6 and 12 mo lifestyle modification intervention based on physical activity, nutrition and behavior therapy, parameters such as body weight, body mass index (BMI), waist circumference, serum alanine aminotransferase (ALT), aspartate aminotransferase values, serum cholesterol, triglycerides, fasting glucose, fasting insulin and visceral fat area (VFA), the liver-spleen ratio and the homeostasis model assessment of insulin resistance (HOMA-IR) were evaluated and compared between participants with and without the intervention.

RESULTS

Seven hundred and twenty-four participants were assigned to the lifestyle intervention group (LS) and 363 participants were assigned to the control group (CON). After the intervention, body weights in the LS group were significantly decreased compared to those in the CON group at 6 mo (11.59% ± 4.7% vs 0.4% ± 0.2%, P = 0.001) and at 12 mo (12.73% ± 5.6% vs 0.9% ± 0.3%, P = 0.001). Compared with the CON group, BMI was more decreased in the LS group after 6 and 12 mo (P = 0.043 and P = 0.032). Waist circumference was more reduced in the LS group than in CON (P = 0.031 and P = 0.017). After the 6 and 12 mo intervention, ALT decreased significantly in the LS group (P = 0.003 and P = 0.002). After 6 and 12 mo, the metabolic syndrome rate had decreased more in the LS group compared with the CON group (P = 0.026 and P = 0.017). After 12 mo, the HOMA-IR score decreased more obviously in the LS group (P = 0.041); this result also appeared in the VFA after 12 mo in the LS group (P = 0.035).

CONCLUSION

Lifestyle intervention was effective in improving NAFLD in both 6 and 12 mo interventions. This intervention offered a practical approach for treating a large number of NAFLD patients in the Chengyang District of Qingdao.

Epidemiology of a fast emerging disease in the Asia-Pacific region: non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is rapidly increasing in the Asia-Pacific and affects up to 30 % of the general population. In younger children, prevalence has been reported to be between 2.1 and 4.5 %. The prevalence of NAFLD increases with increasing age. NAFLD is more prevalent in men than women, but this trend fades in older age group. NAFLD is one of the most common causes of raised serum ALT levels and the latter is closely related to the presence of features of metabolic syndrome. NAFLD may contribute to metabolic syndrome in a similar way as visceral adiposity and can be an early predictor of metabolic disorders. NAFLD increases the risk of developing diabetes mellitus and is closely related to degree of glucose intolerance. A significant proportion of patients with NAFLD have impaired glucose tolerance or diabetes mellitus but with normal fasting blood glucose, highlighting the importance of oral glucose tolerance test in NAFLD patients with normal fasting blood glucose. Besides liver-related complications, NAFLD has been associated with cardiovascular complications, hyperuricemia, gout, chronic kidney disease, gallstone disease, colorectal adenomatous polyp, and polycystic ovarian syndrome. NAFLD seems to be related to host metabolic factors rather than viral factors and does not seem to affect severity of the liver disease in patients with chronic hepatitis B. On the other hand, hepatic steatosis may be related to both host metabolic and viral factors in patients with chronic hepatitis C and seems to adversely impact on the severity of liver disease and possibly response to antiviral therapy.

Neutrophil to lymphocyte ratio: a new marker for predicting steatohepatitis and fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic steatohepatitis (NASH), the most severe form of nonalcoholic fatty liver disease (NAFLD), is associated with inflammation and increased oxidative stress. The neutrophil/lymphocyte ratio (N/L) integrates information on the inflammatory milieu and physiological stress.

AIMS

The aim of this study was to determine the utility of N/L ratio to predict the presence of NASH in patients with NAFLD.

METHODS

Our cohort consisted of 101 consecutive patients undergoing liver biopsy for clinical suspicion of NAFLD. Patients were divided into two groups: NASH group (n = 50) and not NASH group (n = 51). The stage of fibrosis was measured using a 4-point scale. The total white cell count, neutrophil and lymphocyte counts were recorded, and the N/L ratio was calculated.

RESULTS

The mean age was 49.5 (± 10.8) years and the mean BMI was 31.4 (± 4.9) kg/m(2) . Patients with NASH had a higher N/L ratio compared with patients with not NASH [2.5 (1.9-3.3) and 1.6 (1.2-2.0), respectively, P < 0.001]. The N/L ratio correlated with the NAFLD activity score and its individual components (steatosis, inflammation and ballooning P < 0.001). Patients with advanced fibrosis (F3-4) had an elevated N/L ratio [2.9 (2.0-3.9)] compared with patients with fibrosis stage 1-2 [1.8 (1.2-2.2)], P < 0.001. For each one-unit increase in N/L ratio, the likelihood of having NASH increased by 70% and the likelihood of having fibrosis increased by 50%.

CONCLUSION

The N/L ratio is higher in patients with NASH and advanced fibrosis. This ratio can be used as a novel noninvasive marker to predict advanced disease.

Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, and its worldwide prevalence continues to increase with the growing obesity epidemic. This study assesses the epidemiology of NAFLD in adults based on clinical literature published over the past 30 years.

AIM

To review epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults based on clinical literature published over the past 30 years.

METHODS

An in-depth search of PubMed (1980-2010) was based on five search terms: 'non-alcoholic fatty liver disease' OR 'non-alcoholic steatohepatitis' OR 'fatty liver' OR 'steatosis' AND 'incidence' [MeSH Terms] OR 'prevalence' [MeSH Terms] OR 'natural history'. Studies of paediatric cohorts were excluded. Articles were categorised by topic and summarised, noting generalisations concerning their content.

RESULTS

Four study categories included NAFLD incidence, prevalence, risk factors and natural history. Studies related to NAFLD prevalence and incidence indicate that the diagnosis is heterogeneous and relies on a variety of assessment tools, including liver biopsy, radiological tests such as ultrasonography, and blood testing such as liver enzymes. The prevalence of NAFLD is highest in populations with pre-existing metabolic conditions such as obesity and type II diabetes. Many studies investigating the natural history of NAFLD verify the progression from NASH to advanced fibrosis and hepatocellular carcinoma.

CONCLUSIONS

Non-alcoholic fatty liver disease is the most common cause of elevated liver enzymes. Within the NAFLD spectrum, only NASH progresses to cirrhosis and hepatocellular carcinoma. With the growing epidemic of obesity, the prevalence and impact of NAFLD continues to increase, making NASH potentially the most common cause of advanced liver disease in coming decades.

Comparative study on antioxidant capacity of flavonoids and their inhibitory effects on oleic acid-induced hepatic steatosis in vitro

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease and its incidence is rising worldwide. We compared the antioxidant capacity of seventeen flavonoids with their inhibitory effects on oleic acid-induced triglyceride (TG) over-accumulation in HepG2 cells. The results showed significant correlations (P < 0.01) between the inhibition of intracellular TG levels and the suppression effects on reactive oxygen species. Nevertheless, the radical-reducing activities of flavonoids assessed by chemical assays (cyclic voltammetry and Folin-Ciocalteu reagent assay) were poorly correlated with their intracellular TG inhibitory effects. The relationships between structural properties of flavonoids and their inhibitory effects on TG over-accumulation were discussed.

[Nonalcoholic fatty liver disease]

NAFLD encompasses a spectrum of liver diseases including simple steatosis and nonalcoholic steatohepatitis (NASH), which is characterized by inflammation and hepatocyte ballooning on a background of steatosis. NAFLD, the hepatic manifestation of the metabolic syndrome, has become one of the most common causes of chronic liver diseases over the last decade in developed countries as well as in low and middle-income regions owing to dramatic epidemic proportions of obesity and diabetes worldwide. While simple steatosis has mostly a benign course, NASH can lead to fibrosis, cirrhosis and hepatocellular carcinoma. Insulin resistance is considered as the cornerstone in the development of NAFLD/NASH. Liver biopsy remains the gold standard for the diagnosis of NASH. However, non-invasive markers of NASH and fibrosis represent interesting tools to identify patients with severe liver injuries. Even if insulin sensitizers and hepatoprotective agents are promising drugs, no medication has been currently approved for the treatment of NASH. Diet, exercise and control of the metabolic disorders still represent crucial therapeutic options for the management of NAFLD/NASH.

Non-alcoholic fatty liver disease's prevalence and impact on alanine aminotransferase associated with metabolic syndrome in the Chinese

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) is becoming a major public health hazard in China. The present study aimed to estimate the prevalence of NAFLD, NAFLD with abnormal serum alanine aminotransferase (ALT) levels, and determine the potential associations of ALT levels with the components of metabolic syndrome (MetS) in the absence or presence of NAFLD in Chinese adults.

METHODS

A population-based cross-sectional survey was conducted with 2226 participants. Physical examinations, laboratory tests and hepatic ultrasounds were performed. Individuals were further stratified into higher or lower ALT subgroups with the upper quartiles of ALT in this population. The MetS was identified according to the criteria of the Chinese Joint Committee for Developing Chinese Guidelines (JCDCG).

RESULTS

The standardized prevalence of NAFLD was 23.3% (NAFLD with abnormal ALT levels, 3.1%), 26.5% (NAFLD with abnormal ALT levels, 5.1%) in males, and 19.7% (NAFLD with abnormal ALT levels, 0.9%) in females. Multivariate logistic analysis revealed that higher ALT was significantly associated with elevated triglyceride (TG) in the non-NAFLD participants, independent of age, smoking status, drinking status, and other MetS-related measures with odds ratios (95% confidence intervals) of 3.4 (1.6-7.1) and 2.3 (1.4-3.7) in males and females, respectively. On the other hand, the higher ALT was statistically associated with elevated TG and hyperglycemia in the NAFLD cases with odds ratios of 2.2 to 2.5 (P<0.05).

CONCLUSIONS

The prevalence of NAFLD has become epidemic in Shanghai adults. NAFLD combined with ALT levels may be used to identify the individuals at the different risk levels of metabolic disorders.

Ethanol extract of fructus schisandrae decreases hepatic triglyceride level in mice fed with a high fat/cholesterol diet, with attention to acute toxicity

Effects of the ethanol extract of Fructus Schisandrae (EtFSC) on serum and liver lipid contents were investigated in mice fed with high fat/cholesterol (HFC) diet for 8 or 15 days. The induction of hypercholesterolemia by HFC diet caused significant increases in serum and hepatic total cholesterol (TC) levels (up to 62% and 165%, resp.) and hepatic triglyceride (TG) levels (up to 528%) in mice. EtFSC treatment (1 or 5 g/kg/day for 7 days; from Day 1 to 7 or from Day 8 to 14, i.g.) significantly decreased the hepatic TG level (down to 35%) and slightly increased the hepatic index (by 8%) in hypercholesterolemic mice. Whereas fenofibrate treatment (0.1 g/kg/day for 7 days, i.g.) significantly lowered the hepatic TG level (by 61%), it elevated the hepatic index (by 77%) in hypercholesterolemic mice. Acute toxicity test showed that EtFSC was relatively non-toxic, with an LD₅₀ value of 35.63 ± 6.46 g/kg in mice. The results indicate that EtFSC treatment can invariably decrease hepatic TG in hypercholesterolemic mice, as assessed by both preventive and therapeutic protocols, suggesting its potential use for fatty liver treatment.

Risk factors for serum alanine aminotransferase elevation: A cross-sectional study of healthy adult males in Tokyo, Japan

BACKGROUND

Liver-protective effects of light-to-moderate alcohol consumption have been suggested.

AIMS

To determine predictors of ALT elevation in asymptomatic subjects with and without ultrasonographical evidence of fatty liver.

METHODS

Cross-sectional survey of 9703 healthy males. Exclusion criteria were HBV or HCV infection, any use of hepatotoxic medication, history of alcohol abuse, chronic renal or hepatic failure, or treatment for metabolic disorders. Presence of fatty liver was evaluated by ultrasonography; visceral adipose tissue (VAT) was measured by computed tomography (CT).

RESULTS

7148 males (mean age, 50.3±7.8 years) were included; 2406 (33.7%) had fatty liver at ultrasonography. ALT was elevated in 163 (3.4%) and 554 subjects (23.0%) of fatty liver-negative and fatty liver-positive subgroups, respectively. Light (40-140g/week) alcohol consumption was significantly and independently associated with reduced prevalence of ALT elevation in the fatty liver-negative subgroup (OR=0.568, 95% CI=0.342-0.943, P=0.029). ALT elevation was significantly related to age, VAT, high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) in the fatty liver-negative subgroup.

CONCLUSION

Light alcohol consumption is not associated with serum ALT elevation in the Japanese male population. Metabolic syndrome factors are significantly associated with prevalence of ALT elevation, irrespective of the presence of fatty liver.

Comparison of routine blood parameters and blood biochemical parameters between patients with alcoholic and non-alcoholic fatty liver disease

AIM: To compare routine blood parameters and blood biochemical parameters between patients with alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD).

METHODS: A total of 1 203 subjects, who underwent physical examination, including measurement of abdominal circumference and blood pressure, routine blood examination, biochemical examination and two-dimensional ultrasound, were included in this study. Of these subjects, 509 (415 men and 94 women) were diagnosed with fatty liver disease (FLD) and 694 (446 men and 248 women) without FLD by two-dimensional ultrasound. According to the Guidelines for the Diagnosis and Treatment of Alcoholic Liver Disease, subjects with FLD were divided into two groups: AFLD group (n = 106, 105 men and 1 woman) and NAFLD group (n = 403, 310 men and 93 women).

RESULTS: Subjects with FLD had a younger mean age and a higher BMI than subjects without FLD (P = 0.011 and 0.000, respectively). WBC, RBC, HGB, ALT, AST, GGT, ALB, TG, TC, LDL-C, FBG, UA (P < 0.001 for all), ALP (P = 0.015), TP (P = 0.026), AST/PLT ratio (P = 0.001), AST/ALT ratio (P < 0.001), and GGT/PLT ratio (P < 0.001) were higher and HDL-C, AST/GGT ratio, and TBIL/GGT ratio (P < 0.001 for all) were lower in subjects with FLD than in those without FLD. Subjects with AFLD had a younger mean age (P < 0.001), a higher HGB, GGT, ALB, UA (P < 0.001 for all), TG, AST, RBC, ALT (P = 0.007, 0.005, 0.011 and 0.027, respectively), AST/PLT ratio, AST/ALT ratio, and GGT/PLT ratio (P = 0.012, 0.014 and 0.002, respectively), and a lower UREA, AST/GGT ratio and TBIL/GGT ratio (P < 0.001 for all) than those with NAFLD.

CONCLUSION: Routine blood examination and blood biochemical examination are useful in distinguishing patients with and without FLD as well as those with AFLD and NAFLD.

Genetic variation in the GCKR gene is associated with non-alcoholic fatty liver disease in Chinese people

Recent genome-wide association studies reported that GCKR rs780094 polymorphism is associated with elevated fasting serum triglyceride levels and elevated levels of C-reactive protein (CRP). There are a ample of data on the association between circulating triglyceride, CRP concentrations and risk of non-alcoholic fatty liver (NAFLD). To determine whether the GCKR rs780094 polymorphism contributes to the development of non-alcoholic fatty liver, a case-control study was performed in 903 Chinese subjects. Among study population, 436 patients with B-mode ultrasound-proven NAFLD (318 with steatosis hepatis I°, 90 with steatosis hepatis II° and 28 with steatosis hepatis III°) and 467 controls were genotyped by using TaqMan allelic discrimination assays. We confirmed the association of GCKR rs780094 with NAFLD in Chinese people (OR = 1.607, 95% CI 1.139-2.271, P[dom] = 7.2 × 10(-3)). In this study, polymorphism in GCKR rs780094 was not significantly associated with the degree of fatty infiltration of the liver. In addition, the T-allele of GCKR rs780094 was significantly associated with increasing fasting triglyceride (P[add] = 3.8 × 10(-4)) and CRP (P[add] = 2.9 × 10(-4)) concentrations after adjusting for age, gender, and BMI. The association with NAFLD remained significant after adjustment for triglyceride, while adjustment for CRP abolished the association. Genetic variation in GCKR gene rs780094 polymorphism contributes to the risk of NAFLD in Chinese people. The effect of genotype on NAFLD is probably mediated through chronic low-grade systemic inflammation rather than through dislipidemia.

Cardiovascular risk factors, nonalcoholic fatty liver disease, and carotid artery intima-media thickness in an adolescent population in southern Italy

The objective of this study was to determine, in an adolescent population, the prevalence of nonalcoholic fatty liver disease (NAFLD) and the association of NAFLD and cardiovascular risk factors with carotid artery intima-media thickness (IMT), a marker of subclinical atherosclerosis. The authors conducted a population-based study among 642 randomly selected adolescents aged 11-13 years in Reggio Calabria, southern Italy, between November 2007 and October 2008. Prevalences of overweight and obesity were 30.5% and 13.5%, respectively. The overall prevalence of NAFLD was 12.5%, increasing to 23.0% in overweight/obese adolescents. In univariate analysis, increased IMT was positively associated with the presence of NAFLD, body mass index (BMI), waist circumference, systolic blood pressure (all P's < 0.001), diastolic blood pressure (P = 0.006), gamma-glutamyl transpeptidase (P = 0.006), alanine aminotransferase (P = 0.007), and C-reactive protein (P = 0.008) and was inversely associated with high density lipoprotein cholesterol (P < 0.001). In multivariate analysis, NAFLD (P = 0.002), BMI (P = 0.004), waist circumference (P = 0.003), and systolic blood pressure (P = 0.005) retained significant associations. The authors conclude that NAFLD, BMI, waist circumference, and systolic blood pressure are independent markers of increased IMT in a random sample of adolescents.

Fatty liver is associated with dyslipidemia and dysglycemia independent of visceral fat: the Framingham Heart Study

Obesity is not uniformly associated with the development of metabolic sequelae. Specific patterns of body fat distribution, in particular fatty liver, may preferentially predispose at-risk individuals to disease. In this study, we characterize the metabolic correlates of fat in the liver in a large community-based sample with and without respect to visceral fat. Fatty liver was measured by way of multidetector computed tomography of the abdomen in 2,589 individuals from the community-based Framingham Heart Study. Logistic and linear regression were used to determine the associations of fatty liver with cardio-metabolic risk factors adjusted for covariates with and without adjustment for other fat depots (body mass index, waist circumference, and visceral adipose tissue). The prevalence of fatty liver was 17%. Compared with participants without fatty liver, individuals with fatty liver had a higher adjusted odds ratio (OR) of diabetes (OR 2.98, 95% confidence interval [CI] 2.12-4.21), metabolic syndrome (OR 5.22, 95% CI 4.15-6.57), hypertension (OR 2.73, 95% CI 2.16-3.44), impaired fasting glucose (OR 2.95, 95% CI 2.32-3.75), insulin resistance (OR 6.16, 95% CI 4.90-7.76); higher triglycerides, systolic blood pressure (SBP), and diastolic blood pressure (DBP); and lower high-density lipoprotein (HDL) and adiponectin levels (P < 0.001 for all). After adjustment for other fat depots, fatty liver remained associated with diabetes, hypertension, impaired fasting glucose, metabolic syndrome, HDL, triglycerides, and adiponectin levels (all P < 0.001), whereas associations with SBP and DBP were attenuated (P > 0.05).

CONCLUSION

Fatty liver is a prevalent condition and is characterized by dysglycemia and dyslipidemia independent of visceral adipose tissue and other obesity measures. This work begins to dissect the specific links between fat depots and metabolic disease.

Light and moderate alcohol consumption significantly reduces the prevalence of fatty liver in the Japanese male population

OBJECTIVES

The effect of alcohol consumption on the liver is controversial. Recent reports have suggested that moderate alcohol consumption decreases the prevalence of elevated alanine aminotransferase levels. The role of alcohol consumption in the development of fatty liver (FL), however, has not been studied definitively. The aim of this study was to examine the association between alcohol consumption and FL in a large Japanese population.

METHODS

A total of 7,431 asymptomatic male subjects who underwent a complete medical survey in our institute between May 2007 and July 2008 were recruited. Cases positive for hepatitis B or C viruses, potential hepatotoxic drug intake, or under treatment for metabolic disorders were excluded. FL was defined by ultrasonography. Visceral and subcutaneous adipose tissues (VAT and SAT) were measured by computed tomography. Independent and significant predictors associated with FL were determined by multiple logistic regression analysis.

RESULTS

Of the initial study candidates, 130 (1.7%) were positive for hepatitis B and 66 (0.8%) were positive for hepatitis C. On the basis of the inclusion and exclusion criteria, 5,599 men (50.9+/-8.1 years) were studied cross-sectionally. Light (40-140 g/week) and moderate (140-280 g/week) alcohol consumption significantly and independently reduced the likelihood of FL (odds ratio=0.824 and 0.754, 95% confidence interval=0.683-0.994 and 0.612-0.928, P=0.044 and 0.008, respectively) by multivariate analysis after adjusting for potential confounding variables. VAT, SAT, low-density lipoprotein, triglycerides, and fasting blood glucose were significant predictors of the increased prevalence of FL, whereas age was a predictor of the decreased prevalence of FL.

CONCLUSIONS

The prevalence of FL was significantly and independently decreased by light and moderate alcohol consumption in men of an asymptomatic Japanese population.

Neonatal intrahepatic cholestasis caused by citrin deficiency: clinical and laboratory investigation of 13 subjects in mainland of China

BACKGROUND

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is a novel inborn error of metabolism due to dysfunction of citrin protein, and much more information about this new disease is still needed for its clinical management.

AIMS

To investigate in detail the clinical and laboratory features of NICCD.

PATIENTS

13 NICCD subjects in mainland of China diagnosed in our department since 2006.

METHODS

The anthropometric parameters of the patients at birth were compared with controls, representative biochemical changes and metabolome findings were investigated cross-sectionally, and mutations in the causative gene SLC25A13 were analyzed by protocols established previously.

RESULTS

The patients showed reduced birth weight, length and ponderal index. Main clinical manifestations consisted of jaundice, hepato/hepatosplenomegaly and steatohepatosis on ultrasonography. Biochemical analysis revealed intrahepatic cholestasis, delayed switch of AFP to albumin, and elevated triglyceride, total cholesterol and LDL-cholesterol together with reduced HDL-cholesterol. Metabolome findings included co-existence of markers for galactosemia and tyrosinemia in urine, and elevated Cit, Met, Thr, Tyr, Lys, Arg and Orn in blood. Mutations of 851-854del, IVS6+5G>A, 1638-1660dup, A541D, IVS16ins3kb, R319X and G333D were detected in the gene SLC25A13.

CONCLUSIONS

The diagnosis of NICCD cannot be established based just on the numerous but non-specific clinical manifestations and biochemical changes. The relatively specific metabolome features provide valuable tools for its screening and diagnosis, while SLC25A13 mutation analysis should be taken as one of the reliable tools for the definitive diagnosis. The body proportionality at birth, steatohepatosis on ultrasonography, delayed switch of AFP to albumin, dyslipidemia pattern, urinary metabolome features and the novel mutation G333D expanded the clinical spectrum of NICCD.

Resveratrol down-regulates hepatic cyclooxygenase-2 expression in mice with nonalcoholic steatohepatitis

AIM: To investigate the effect of resveratrol on gene expression of cyclooxygenase (COX)-2 in mice with diet-induced nonalcoholic steatoheptatitis (NASH).

METHODS: Thirty male C57BL/6J mice were assigned randomly to three groups: normal control group, high fat group (HF group) and high fat resveratrol treatment group (HR group). The mice in normal control group (n = 10) were fed with standard diet. The mice in HF group (n = 10) and in HR group (n = 10) were fed with high fat diet. After 8-week high fat diet, the mice in HR group were fed with resveratrol 400 mg/(kg•d) for 16 wk. Hepatic COX-2 expression was determined using RT-PCR and Western blot.

RESULTS: Steatoheptatitis was discernable in HF group and was markedly alleviated in HR group. COX-2 were not expressed in normal mouse liver. The mRNA expression and protein expression of COX-2 were significantly lower in HR group than those in HF group(0.76% ± 0.18% vs 1.48% ± 0.23%, 11.2% ± 3.5% vs 27.9% ± 4.6%, both P < 0.01), but not returned to normal level.

CONCLUSION: COX-2 may play an important role in NASH pathogenesis. Resveratrol improves NASH at least partly by downregulating expression of COX-2 in the liver.