The Evolving Role of Fetuin-A in Nonalcoholic Fatty Liver Disease: An Overview from Liver to the Heart.

Nonalcoholic fatty liver disease (NAFLD) is strongly associated to the features of metabolic syndrome which can progress to cirrhosis, liver failure and hepatocellular carcinoma. However, the most common cause of mortality in people with NAFLD is not liver-related but stems from atherosclerotic cardiovascular disease (CVD). The prevalence of NAFLD is on the rise, mainly as a consequence of its close association with two major worldwide epidemics, obesity and type 2 diabetes (T2D). The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression and CVD have not been completely elucidated. Human fetuin-A (alpha-2-Heremans Schmid glycoprotein), a glycoprotein produced by the liver and abundantly secreted into the circulation appears to play a role in insulin resistance, metabolic syndrome and inflammation. This review discusses the links between NAFLD and CVD by specifically focusing on fetuin-A's function in the pathogenesis of NAFLD and atherosclerotic CVD.

Betatrophin Levels Are Related to the Early Histological Findings in Nonalcoholic Fatty Liver Disease.

Betatrophin, a liver hormone, regulates glucose and lipid metabolism. We investigated the betatrophin levels in nonalcoholic fatty liver disease (NAFLD) and searched for any relationship with histological severity and metabolic parameters. Fifty males with NAFLD [Nonalcoholic Steatohepatitis (NASH) (n = 32); non-NASH (n = 18)] and 30 healthy controls were included. Plasma betatrophin was measured by ELISA method. Insulin sensitivity was assessed by HOMA-IR index. Histological features were scored by the semi quantitative classification and combined as the NAFLD activity score (NAS). Betatrophin levels in the non-NASH group were significantly higher than the controls. Betatrophin was positively correlated to the age, waist circumference, total cholesterol, triglycerides, LDL cholesterol, glucose, insulin, HOMA-IR index and gamma glutamyl transpeptidase levels, and negatively correlated to the steatosis and NAS. In the stepwise linear regression analysis, the triglyceride (ß = 0.457, p < 0.001), glucose (ß = 0.281, p = 0.02) and NAS (ß = -0.260, p = 0.03) were the independent determinants of betatrophin. Betatrophin levels are higher in the early stages of NAFLD and tend to decrease when the disease progresses. This could be an important preliminary mechanistic finding to explain the increased frequency of glucose intolerance during the course of NAFLD.

The relationship between blood urea nitrogen levels and metabolic, biochemical, and histopathologic findings of nondiabetic, nonhypertensive patients with nonalcoholic fatty liver disease.

BACKGROUND/AIM: Nonalcoholic fatty liver disease (NAFLD) is known as the most common cause of chronic liver disease. It is accepted that the leading cause of death in patients with NAFLD is from coronary events. Blood urea nitrogen (BUN) was used as a prognostic indicator for cardiovascular disease. We aimed to investigate the relationship between BUN levels and metabolic, biochemical, and histopathologic findings of nondiabetic patients with NAFLD. MATERIALS AND METHODS: A total of 195 male patients with biopsy proven NAFLD and 82 healthy controls with normal liver and renal function tests and normal abdominal ultrasonography were enrolled in the study. BUN levels were reviewed retrospectively. RESULTS: The mean BUN levels of patients and controls were 13.07 (11.3-15.41) and 13.31 (10.97-15.87) mg/dL respectively. Patients were grouped as simple steatosis (n = 33, 16.9%), borderline nonalcoholic steatohepatitis (n = 64, 32.8%), and nonalcoholic steatohepatitis (n = 98, 50.3%), and the BUN levels of the histologic subgroups were 13.14 ± 2.89, 14.34 ± 3.04, and 13.71 ± 3.21 mg/dL, respectively. We could not find any differences between the patient group and control group with respect to BUN levels. CONCLUSION: Our findings showed that there was no relationship between BUN levels and metabolic, biochemical, and histopathologic findings of patients with NAFLD. Further investigations, including in patients with late stages of NAFLD, are required.

Low- and high-density lipoprotein subclasses in subjects with nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is associated with increased cardiometabolic risk. Although dyslipidemia represents a key factor in this disease, its impact on serum levels of distinct lipoprotein subfractions is largely unknown. OBJECTIVE: To assess the full low-density lipoprotein (LDL) and high-density lipoprotein (HDL) profiles in patients with NAFLD. METHODS: Seven LDL and 10 HDL subfractions were assessed by gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA) in men with biopsy proven NAFLD (simple steatosis [n = 17, age, 34 ± 7 years] and nonalcoholic steatohepatitis [NASH; n = 24, age, 32 ± 6 years]). Exclusion criteria included robust alcohol consumption, infection with hepatitis B or C virus, body mass index ≥ 40 kg/m(2), diabetes mellitus, and hypertension. RESULTS: Compared with simple steatosis, NASH patients had similar body mass index, homeostasis model assessment of insulin resistance index and plasma lipids, with increased levels of both aspartate aminotransferase and alanine transaminase. NASH subjects had lower levels of larger LDL1 (10 ± 4 vs 13 ± 4%, P = .010) and increased smaller LDL3 and LDL4 particles (9 ± 5 vs 5 ± 5%, P = .017 and 3 ± 3 vs 1 ± 2%, P = .012, respectively). No changes were found in the HDL subclass profile. By multiple regression analysis, we found that NASH was associated only with increased levels of LDL3 (P = .0470). CONCLUSIONS: The increased levels of small, dense LDL3 and LDL4 in NASH may help to at least partly explain the increased risk for atherosclerosis and cardiovascular diseases in these patients.

Neutrophil-to-lymphocyte ratio is not a predictor of liver histology in patients with nonalcoholic fatty liver disease.

OBJECTIVES: It has been reported that the neutrophil-to-lymphocyte ratio (NLR) can be measured relatively easily and can serve as a valuable index for much clinical pathology. The aim of this study was to investigate the association between NLR and hepatic histological findings in patients with nonalcoholic fatty liver disease (NAFLD). DESIGN AND METHODS: A total of 226 consecutive patients with biopsy-proven NAFLD [nonalcoholic steatohepatitis (NASH, n=105), borderline-NASH (n=74), and simple steatosis (n=47)] were enrolled. NASH and fibrosis were diagnosed histologically using the NAFLD Clinical Research Network criteria. RESULTS: Significant differences were found in aspartate aminotransferase (P<0.001), alanine aminotransferase (P<0.001) levels, and white blood cell (P=0.007) and neutrophil counts (P=0.042) between the three groups of patients. In addition, significantly higher BMI (P=0.024), waist circumference (P=0.011), aspartate aminotransferase (P=0.003), alanine aminotransferase (P=0.005), insulin (P=0.008), and homeostasis model assessment-insulin resistance (P=0.009) levels were found in patients with fibrosis (n=133) in comparison with those without fibrosis (n=93). There was no correlation between NLR and glucose, homeostasis model assessment-insulin resistance, lipid parameters, and the NAFLD activity score. Analysis of the NLR in relation to histological findings also showed no association between these parameters. CONCLUSION: To the best of our knowledge, this is the largest study that has investigated these relationships in this clinically relevant condition. The findings of the present study show that NLR is not associated with the severity of hepatic inflammation or fibrosis and thus cannot be recommended as a surrogate marker of liver injury in patients with NAFLD.

The relationship of circulating fetuin-a with liver histology and biomarkers of systemic inflammation in nondiabetic subjects with nonalcoholic fatty liver disease.

BACKGROUND/AIMS: Fetuin-A, a glycoprotein with anti-inflammatory properties, plays an important role in counter-regulating inflammatory responses. It has also been associated with insulin resistance and metabolic syndrome. We aimed to investigate circulating concentrations of fetuin-A and its possible association with hepatic and systemic inflammation in nondiabetic subjects with nonalcoholic fatty liver disease (NAFLD). PATIENTS AND METHODS: We included 105 nondiabetic male subjects with NAFLD [nonalcoholic steatohepatitis (NASH, n = 86) and simple steatosis (SS, n = 19)]. Plasma levels of fetuin-A and markers of inflammation [high-sensitive C reactive protein (hsCRP), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and adiponectin] were measured by enzyme-linked immunosorbent assay method. Insulin sensitivity was determined by homeostasis model assessment of insulin resistance (HOMA-IR) index. RESULTS: Fetuin-A was negatively correlated with age (r = -0.27, P = 0.006), however there was no association between fetuin-A and body mass index, waist circumference (WC), glucose, insulin, HOMA-IR, lipid parameters, and inflammatory markers. In addition, no significant association was observed between fetuin-A and histological findings including liver fibrosis. CONCLUSION: This study demonstrated that plasma fetuin-A levels are not correlated with the hepatic histology and systemic markers of inflammation in nondiabetic subjects with NAFLD. Our data also suggested that age is significantly associated with fetuin-A in this clinically relevant condition.

Insulin Resistance but Not Visceral Adiposity Index Is Associated with Liver Fibrosis in Nondiabetic Subjects with Nonalcoholic Fatty Liver Disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is associated with obesity, type 2 diabetes mellitus, and dyslipidemia. It is well known that the presence of visceral fat increases the risk for metabolic complications of obesity, especially NAFLD. The visceral adiposity index (VAI), a novel marker of visceral fat dysfunction, shows a strong association with insulin resistance and also cardiovascular and cerebrovascular events. However, there is conflicting data regarding the association between VAI and NAFLD. Our aim was to assess the relationship between VAI, insulin resistance, adipocytokines, and liver histology, in nondiabetic subjects with NAFLD. METHODS: A total of 215 male patients with biopsy-proven NAFLD were included. Among this group, serum levels of adiponectin, tumor necrosis factor-α (TNF-α, interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) were measured in 101 patients whose blood samples were available. RESULTS: High gamma-glutamyl transferase (GGT), high total cholesterol (TC), high triglycerides (TGs), low high-density lipoprotein cholesterol (HDL-C), and presence of metabolic syndrome were significantly associated with higher VAI, although only higher GGT and TC were independent factors on multiple linear regression analysis. On the other hand, no significant association was found between VAI and adiponectin, TNF-α, IL-6, and hsCRP levels. The multivariate analysis of variables in patients with (n=124) and without (n=91) fibrosis showed that only higher homeostasis model assessment of insulin resistance value was independently associated with liver fibrosis. CONCLUSIONS: Our findings suggest that VAI is not related to the severity of hepatic inflammation or fibrosis in nondiabetic patients with NAFLD. The lack of association between the adipocytokines and VAI also implies that the VAI may not be a significant indictor of the adipocyte functions.

The relationship of serum uric acid with non-alcoholic fatty liver disease.

OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is a clinicopathological entity which is characterized by the presence of fat droplets in hepatocytes without alcohol consumption, representing a spectrum of hepatic injuries, ranging from simple steatosis (SS) to non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. In recent years, experimental and observational studies suggest a role for serum uric acid (SUA) in NAFLD. However, there are few reports investigating SUA in histologically proven NAFLD. The aim of the present study was to evaluate the relationship of SUA with liver histology in non-diabetic patients with NAFLD. DESIGN AND METHODS: A total of 242 male patients with NAFLD (102 with NASH and 140 with SS) were included. Histopathological evaluation was carried out according to Kleiner's scoring scale. Hyperuricemia was diagnosed as SUA of more than 7 mg/dL. RESULTS: The prevalence of hyperuricemia was 33.4%. SUA levels in patients with NASH were significantly higher than those of SS (p=0.035). Univariate and multivariate analyses both demonstrated that hyperuricemia had a significant association with younger age [OR (95%CI), 0.930 (0.884-0.979), p=0.005], higher body mass index [OR (95%CI), 1.173 (1.059-1.301), p=0.002] and hepatocellular ballooning [OR (95%CI), 1.678 (1.041-2.702), p=0.033]. CONCLUSIONS: Hyperuricemia is a common finding in patients with NAFLD and is independently associated with early histological findings in this clinically relevant condition. Further longitudinal studies are needed to characterize the role of SUA in the natural history of NAFLD.

Association of plasma visfatin with hepatic and systemic inflammation in nonalcoholic fatty liver disease.

BACKGROUND: Visfatin is a proinflammatory and insulin-mimetic adipokine contributing to whole body glucose and lipid metabolism. Studies to date are conflicting regarding the relationship between visfatin and non-alcoholic fatty liver disease (NAFLD). The aim of the present study was to evaluate the relationship of circulating visfatin with NAFLD. MATERIAL AND METHODS: The study included 114 NAFLD patients and 60 healthy non-diabetic controls. Plasma visfatin, adiponectin, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) levels were measured by ELISA. High sensitive C-reactive protein (hsCRP) levels were measured by immunoturbidimetric fixed rate method. Insulin sensitivity determined by homeostasis model assessment (HOMA-IR) index. RESULTS: TNF-α, IL-6 and hsCRP levels were higher and, Adiponectin levels were lower in NAFLD group when compared to healthy controls (p < 0.001, for all). However, no difference was found regarding to visfatin levels between two groups. Different histologic subgroups of NAFLD had a significantly higher TNF-α, IL-6 and hsCRP, and lower adiponectin levels than those with controls (p < 0.001, for all). On the other hand, no statistically significant difference was found regarding to visfatin levels among different histologic groups. Visfatin was found to be negatively correlated with TNF-α (r = -0.236, p = 0.011) in NAFLD group. However, no association was found between visfatin and histological findings. CONCLUSION: Our findings show that plasma visfatin levels are not altered in the early stages of NAFLD. However, it is inversely associated with TNF-α. These findings suggest a role for visfatin in protection against liver injury in this widespread disease.

Plasma fetuin-A is associated with endothelial dysfunction and subclinical atherosclerosis in subjects with nonalcoholic fatty liver disease.

OBJECTIVE: Nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of metabolic syndrome (MetS) is closely associated with an increased risk of cardiovascular disease. Fetuin-A is associated with MetS and NAFLD. We investigated the relationship of circulating fetuin-A level with markers of endothelial dysfunction and presence of carotid atherosclerosis in subjects with NAFLD. METHODS: The consecutive 115 patients with NAFLD and age-matched 74 healthy subjects were enrolled. Plasma levels of fetuin-A and markers of endothelial dysfunction [asymmetric dimethyl arginine (ADMA) and adiponectin] were measured by ELISA method. Insulin sensitivity was determined by homeostasis model assessment of insulin resistance (HOMA-IR) index. Carotid artery intima-media thickness (cIMT) was assessed by high-resolution ultrasonography. RESULTS: Fetuin-A and ADMA were higher and, adiponectin was lower in NAFLD group than the control group (P = 0·004, P < 0·001 and P < 0·001, respectively). In addition, NAFLD group had greater cIMT measurements than the controls (P < 0·001). However, no difference was found for fetuin-A, ADMA, adiponectin and cIMT between two groups when the findings were adjusted according to the glucose, lipids and HOMA-IR index. In correlation analysis, fetuin-A was found to be positively correlated with triglyceride (r = 0·23, P = 0·001), HOMA-IR (r = 0·29, P < 0·001), ADMA (r = 0·24, P = 0·001), cIMT (r = 0·3, P = 0·003) and, negatively correlated with HDL-C (r = -0·17, P = 0·02) and adiponectin (r = -0·19, P = 0·01) levels. Multiple linear regression analysis showed that fetuin-A was independently associated with ADMA and cIMT levels. CONCLUSION: This study demonstrated for the first time that circulating fetuin-A in NAFLD is independently associated with endothelial dysfunction and subclinical atherosclerosis.