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.

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.

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.

Circulating vaspin and its relationship with insulin sensitivity, adiponectin, and liver histology in subjects with non-alcoholic steatohepatitis.

OBJECTIVE: Non-alcoholic steatohepatitis (NASH) is closely associated with components of metabolic syndrome. Vaspin is a novel adipocytokine that may link obesity, insulin resistance (IR), and type 2 diabetes mellitus. We aimed to investigate circulating vaspin levels in subjects with NASH and also to search for the association of vaspin with IR, adiponectin, and histological findings. MATERIAL AND METHODS: A total of 50 male patients with NASH and 30 healthy male controls were enrolled. Vaspin and adiponectin were measured with ELISA method. Insulin sensitivity determined by homeostasis model assessment (HOMA-IR) index. RESULTS: Plasma vaspin levels were higher and adiponectin levels were lower in NASH group compared with controls (p < 0.01 and p < 0.001, respectively). However, in multivariate analysis adjusted for glucose and lipid parameters, and HOMA-IR indexes, the difference in vaspin concentrations was disappeared. Nonetheless, the difference regarding the adiponectin levels remained significant between groups (p = 0.03). Vaspin was negatively correlated with low-density lipoprotein cholesterol (r = -0.32, p = 0.03) in subjects with NASH. CONCLUSIONS: This study indicates that circulating vaspin levels are not altered in male subjects with NASH. These results suggest that in the absence of metabolic risk factors, vaspin per se may not be involved in the pathogenesis of NASH.

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.

Levels of soluble CD40 ligand and P-Selectin in nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is linked to an increased risk of cardiovascular disease. We aimed to research whether the levels of soluble P-selectin (sP-selectin) and soluble CD40 ligand (sCD40L), markers of endothelial function, are altered in subjects with NAFLD having no confounding factors for atherosclerosis. sCD40L, sP-selectin, and high-sensitivity C-reactive protein (hsCRP) levels, and homeostasis model assessment of insulin resistance (HOMA-IR) indexes were measured in 50 NAFLD subjects and 30 healthy controls. sCD40L, sP-selectin, and hsCRP levels were not significantly different between two groups (P = 0.48, 0.51, and 0.34, respectively). Body mass index, waist circumference, and insulin levels and HOMA indexes were significantly higher in subjects with NAFLD (all P < 0.001). The present data show that sCD40L and sP-selectin may not contribute to the accelerated atherogenesis associated with this clinically relevant condition.

Circulating levels of interleukin-18 in patients with non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Non-alcoholic fatty liver disease (NAFLD) is strongly associated with obesity and diabetes mellitus. IL-18 is associated with obesity and metabolic syndrome. Our aim was to investigate the relationship of IL-18 with adiponectin and liver histology in subjects with NAFLD who had no additional disorder such as morbid obesity, diabetes mellitus and hypertension. METHODS: Plasma levels of IL-18 and adiponectin were measured by ELISA in 96 male subjects with NAFLD [n = 65 for non-alcoholic steatohepatitis (NASH) and n = 31 for simple steatosis (SS)]. RESULTS: IL-18 levels were not different between the two groups (p = 0.89). There was no significant association of IL-18 with adiponectin, insulin resistance and histopathological findings. Adiponectin was lower in the NASH group compared to the SS group (p = 0.02) and it was found to be negatively correlated with hepatic steatosis and fibrosis (r = -0.442, p < 0.001 and r = -0.292, p = 0.02, respectively). CONCLUSIONS: This study indicates that circulating IL-18 levels are not altered in male subjects with NAFLD. These results suggest that in the absence of metabolic risk factors, IL-18 per se may not be involved in the pathogenesis of NASH and SS.

Elevated plasma levels of apelin in children with type 1 diabetes mellitus.

BACKGROUND: Apelin is a novel adipocytokine produced by white adipose tissue that binds the APJ receptor with high affinity. Insulin may have a role in regulation of apelin synthesis and secretion from the adipose tissue. OBJECTIVE: To investigate blood apelin concentrations in children with type 1 diabetes mellitus (T1DM) and display association of apelin with adiponectin, body mass index (BMI), lipids and insulin sensitivity. METHODS: Thirty patients with T1DM and 45 healthy controls were enrolled. Apelin levels were measured along with BMI, lipids, fasting plasma glucose, HbA1c and adiponectin levels. RESULTS: Plasma apelin and adiponectin levels were significantly higher in the diabetic group when compared to controls. No correlation was found between the apelin blood concentrations and adiponectin, BMI, lipids and insulin sensitivity. CONCLUSIONS: Children with T1DM have significantly increased circulating apelin levels when compared to healthy controls. However, no significant relation was found between the apelin and BMI, glucose, lipids and adiponectin levels, and also insulin sensitivity.

Plasma apelin and ADMA Levels in patients with essential hypertension.

Both apelin and asymetric dymethyl arginine (ADMA) regulate blood pressures. Low apelin and high ADMA levels have been reported in several cardiometabolic disorders. However, there is no data about ADMA and apelin levels in essential hypertension and any relationship between them. We investigated a group of newly diagnosed and untreated 30 young hypertensive men and 30 healthy controls. Apelin levels were significantly lower and the ADMA levels were significantly higher in the patients (p = 0.04 for both). Both ADMA and apelin were related to the systolic blood pressures (SBP) (beta = -0.393, p = 0.003; beta = 0.285, p = 0.03, respectively). Future studies are necessary in order to clearly define the role of ADMA and apelin in the pathogenesis of essential hypertension.

Transforming growth factor ß (TGF-ß) levels in otherwise healthy subjects with impaired glucose tolerance.

INTRODUCTION: Serum transforming growth factor beta (TGF-ß) level is increased in type-2 diabetes mellitus (T2DM) and certain diabetic complications are mediated by this cytokine. Impaired glucose tolerance (IGT) is a prediabetic condition, and confers a risk for the development of certain diabetes-specific complications. However, no data is available regarding the alteration of TGF-ß in IGT subjects. Therefore, we aimed to investigate TGF-ß levels in otherwise healthy subjects with IGT. MATERIAL AND METHODS: Thirty IGT subjects and 30 subjects relatively matched for age, sex and body mass index with normal glucose tolerance were enrolled. Subjects with overt diabetes, cardiovascular, renal or inflammatory disease, or on any medication were excluded. Relevant laboratory examinations were performed by routine methods. Assessment of TGF-ß was made by a commercially available enzyme-linked immunosorbent assay kit. IGT and control subjects were compared for their clinical and laboratory parameters. RESULTS: Serum TGF-ß levels were found to be similar in IGT and normal glucose tolerance subjects (p 〈 0.05). No statistically significant correlation was found between TGF-ß and other laboratory parameters, either in IGT subjects or in the whole study population. CONCLUSIONS: Serum TGF-ß is not elevated in otherwise healthy subjects with IGT. The results of our study imply that the presence of IGT alone is not sufficient to induce TGF-ß elevation; and for the alteration of TGF-ß, worsening of metabolic risk factors may be required.

Ewing's sarcoma of the fibula presenting with venous thrombosis.

Malignancies account for about 20% of incidentally diagnosed venous thromboembolism. Surgery- or chemotherapy-induced risk of thrombosis is also high in patients with cancer. We report on a young male with skeletal Ewing's sarcoma who presented with deep vein thrombosis in the affected limb, which is quite a rare clinical condition. Venous thrombosis of the lower extremities in young patients should prompt the clinician to search for underlying local malignancies.

Plasma visfatin levels in patients with newly diagnosed and untreated type 2 diabetes mellitus and impaired glucose tolerance.

Visfatin, a new adipokine, facilitates adipogenesis and has insulin-mimetic properties. We aimed to investigate the plasma visfatin levels in patients with newly diagnosed and untreated type 2 diabetes mellitus (T2DM) and impaired glucose tolerance (IGT), who had no obesity or hypertension. Twenty-two patients with T2DM, 18 subjects with IGT and 40 healthy controls were enrolled. Visfatin levels were measured along with the BMI, blood pressure, lipids, glucose, insulin, adiponectin and hsCRP levels, and HOMA-IR indexes. Age, sex and BMI were similar in all groups. Visfatin levels were higher in the diabetic group than the controls (p=0.01). There was no significant difference in the visfatin levels between the T2DM and IGT groups as well as IGT group and healthy controls. Plasma visfatin concentrations did not differ between men and women. Visfatin levels did not correlate with BMI, blood pressure, plasma adiponectin, insulin, hsCRP, glucose and lipid levels or HOMA-IR indexes in the three groups. These results indicate that hyperglycemia causes an increase in plasma visfatin levels and, as in people with T2DM but not with IGT, this increase gets more prominent as the glucose intolerance worsens.

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.