甲状腺激素与非酒精性脂肪性肝病研究进展

非酒精性脂肪性肝病(NAFLD)是肝硬化、肝癌和肝移植的重要原因。全球成年人患病率约为25%,且呈现上升趋势。大量的研究表明甲状腺激素(TH)在肝脏脂质代谢和胰岛素抵抗过程中起着重要的作用,甲状腺激素受体激动剂有望成为治疗NAFLD的新型药物。本文就甲状腺激素与NAFLD的研究进展进行了综述。     

Serum ferritin levels are associated with vascular damage in patients with nonalcoholic fatty liver disease

Background and aims

Increased ferritin and body iron stores are frequently observed in nonalcoholic fatty liver disease (NAFLD), associated with heightened susceptibility to vascular damage. Conflicting data have been reported on the role of iron in atherosclerosis, with recent data suggesting that excess iron induces vascular damage by increasing levels of the hormone hepcidin, which would determine iron trapping into macrophages, oxidative stress, and promotion of transformation into foam cells. Aim of this study was to investigate the relationship between iron status and cardiovascular damage in NAFLD.

Methods and results

Vascular damage was evaluated by common carotid arteries intima-media thickness (CC-IMT) measurement and plaque detection by ecocolor-doppler ultrasonography in 506 patients with clinical and ultrasonographic diagnosis of NAFLD, hemochromatosis gene (HFE) mutations by restriction analysis in 342 patients. Serum hepcidin-25 was measured by time-of-flight mass spectrometry in 143 patients. At multivariate analysis CC-IMT was associated with systolic blood pressure, glucose, LDL cholesterol, abdominal circumference, age, and ferritin (p = 0.048). Carotid plaques were independently associated with age, ferritin, glucose, and hypertension. Ferritin reflected iron stores and metabolic syndrome components, but not inflammation or liver damage. Hyperferritinemia was associated with increased vascular damage only in patients with HFE genotypes associated with hepcidin upregulation by iron stores (p < 0.0001), and serum hepcidin-25 was independently associated with carotid plaques (p = 0.05).

Conclusion

Ferritin levels, reflecting iron stores, are independent predictors of vascular damage in NAFLD. The mechanism may involve upregulation of hepcidin by increased iron stores in patients not carrying HFE mutations, and iron compartmentalization into macrophages.     

Serum leptin levels in patients with nonalcoholic chronic liver disease

BACKGROUND/AIMS: The elevated serum leptin level of patients with alcoholic cirrhosis has been reported, however, the precise mechanism is still unknown. Leptin expression and protein synthesis have also been detected in activated hepatic stellate cells in cell cultures, which play a major role in hepatic fibrosis. We evaluated the serum leptin levels of patients with nonalcoholic liver diseases including cirrhosis and chronic hepatitis. We also investigated the hepatic clearance of leptin by determining the serum leptin level in blood samples obtained from the portal and hepatic veins. METHODOLOGY: The serum leptin level of 44 patients with nonalcoholic chronic liver disease (male/female = 21/23, cirrhosis/chronic hepatitis = 30/14) and 40 control subjects (male/female = 20/20) was determined in blood samples obtained from the antecubital vein by enzyme-linked immunosorbent assay. We also assessed the relationship between the leptin level and various biochemical tests of liver function. Additionally, we determined the leptin levels in the portal and the hepatic venous blood (nonalcoholic cirrhosis = 10, nonhepatic disease = 4). RESULTS: There were positive correlations between the serum leptin level and body mass index among males and among females in the liver disease group and in the control group. However, the serum leptin level of the liver disease group and control group did not differ significantly. Among the 44 liver disease patients, only the serum cholesterol level was significantly correlated with the serum leptin level after adjusting for sex and body mass index by multiple regression analysis. Furthermore, the leptin level in hepatic venous blood was significantly lower than that in portal venous blood. However, the ratio of [leptin level in hepatic venous blood]/[leptin level in portal venous blood] in the cirrhosis group, and that in the nonhepatic disease group, did not significantly differ. CONCLUSIONS: The serum leptin level of patients with nonalcoholic liver diseases is not elevated. On the other hand, the serum leptin level of patients with alcoholic cirrhosis has been reported to be elevated. The difference in the serum leptin level of patients with nonalcoholic liver disease and that of patients with alcoholic cirrhosis may be due to a difference in factors such as the levels of cytokines or sex steroids, and/or nutrition. Furthermore, it is likely that leptin is cleared in part by the portosystemic circulation through the liver.     

Serum thioredoxin levels as a predictor of steatohepatitis in patients with nonalcoholic fatty liver disease

BACKGROUND/AIMS: Thioredoxin (TRX) is a stress-inducible thiol-containing protein. The aim of this study was to evaluate the clinical significance of serum TRX in patients with nonalcoholic steatohepatitis (NASH) or simple steatosis. METHODS: Serum TRX levels were determined using an enzyme-linked immunosorbent assay kit in 25 patients with NASH, 15 patients with simple steatosis, and 17 healthy volunteers. RESULTS: Serum TRX levels (medians and (ranges), ng/ml) were significantly elevated in patients with NASH (60.3 (17.6-104.7)), compared to those in patients with simple steatosis (24.6 (16.6-69.7), P=0.0009) and in healthy controls (23.5 (1.3-50.7), P<0.0001). Serum ferritin levels in patients with NASH were also significantly higher than the levels in patients with simple steatosis. The receiver operating characteristic curve confirmed that serum TRX and ferritin levels were predictors for distinguishing NASH from simple steatosis. Higher grades of histological iron staining were observed in NASH than in simple steatosis. Serum TRX tended to increase in accordance with hepatic iron accumulation and the histological severity in patients with NASH. CONCLUSIONS: The pathogenesis of NASH may be associated with iron-related oxidative stress. The serum TRX level is a parameter for discriminating NASH from simple steatosis as well as a predictor of the severity of NASH.     

Serum Fetuin-A levels in obese children with biopsy proven nonalcoholic fatty liver disease

Background and aims

Fetuin-A has been proposed as a marker of liver damage in adults with obesity-related NAFLD. The aim of this study was to test serum fetuin-A concentrations in obese children with NAFLD diagnosed either by ultrasonography or by liver biopsy and to determine its applicability as predictive tool in pediatric NAFLD.

Serum levels of omentin,chemerin and adipsin in patients with biopsy-proven nonalcoholic fatty liver disease

Abstract

Objective. The novel adipokines omentin, chemerin, and adipsin are associated with insulin resistance and the components of the metabolic syndrome. We assayed circulating levels of these molecules and examined their association with clinical, biochemical, and histological phenotypes in patients with nonalcoholic fatty liver disease (NAFLD). Material and methods. Serum levels of omentin, chemerin, and adipsin were assayed by enzyme-linked immunosorbent assay in 99 patients with biopsy-proven NAFLD and 75 control subjects. We analyzed associations between adipokines and the characteristics of patients with NAFLD using multivariable linear regression models. Results. Adipsin levels did not differ between patients and controls, whereas both omentin and chemerin levels were significantly higher in patients with biopsy-proven NAFLD than in controls (both p values <0.001). Serum omentin levels were significantly associated with C-reactive protein (r = 0.29, p < 0.01) and the degree of hepatocyte ballooning (r = 0.27, p < 0.01), whereas chemerin showed a modest association with liver fibrosis (r = 0.22, p = 0.04). After stepwise linear regression analysis adjusting for potential confounders, serum omentin levels retained their independent significance as a predictor of hepatocyte ballooning in patients with NAFLD (β = 1.42; t = 2.79, p < 0.01). Conclusions. Our results suggest that serum omentin levels are raised in patients with NAFLD regardless of potential confounders and represent an independent predictor of hepatocyte ballooning.     

Serum osteopontin levels as a predictor of portal inflammation in patients with nonalcoholic fatty liver disease

BackgroundOsteopontin is a secreted phosphorylated glycoprotein that is expressed by a variety of cell types and that mediates numerous and diverse biological functions.Osteopontin knockout mice are protected from obesity-induced hepatic steatosis. In the present study, we sought to investigate whether serum osteopontin concentrations are associated with liver histology in patients with nonalcoholic fatty liver disease.MethodsSerum levels of osteopontin were measured by enzyme-linked immunosorbent assay in 179 well-characterized patients with nonalcoholic fatty liver referred for liver histology and 123 control subjects.ResultsSerum osteopontin levels were markedly higher in patients with nonalcoholic fatty liver disease than in controls (p < 0.001). Multivariable analysis showed that osteopontin levels were strongly and independently associated with both portal inflammation (β = 0.294, p < 0.01) and serum aminotransferase levels (aspartate aminotransferase: β = 0.295, p < 0.01; alanine aminotransferase; β = 0.285, p < 0.01).ConclusionIn summary, these data demonstrate that serum levels of osteopontin are elevated in nonalcoholic fatty liver disease and are a significant independent predictor of portal inflammation in this clinical entity.     

Serum levels of vaspin, obestatin, and apelin-36 in patients with nonalcoholic fatty liver disease

The novel adipokines vaspin, obestatin, and apelin-36 are associated with insulin resistance and the components of the metabolic syndrome. We assayed circulating levels of these molecules and examined their association with clinical, biochemical, and histologic phenotypes in patients with nonalcoholic fatty liver disease (NAFLD). Serum levels of vaspin, obestatin, and apelin-36 were assayed by enzyme-linked immunosorbent assay in 91 patients with biopsy-proven NAFLD and 81 controls. We analyzed associations between adipokines and the characteristics of patients with NAFLD using multivariable linear regression models. Univariable analysis showed that concentrations of vaspin and apelin-36 were significantly higher in patients with NAFLD than in controls, whereas no differences in obestatin levels were found. Serum vaspin levels showed a statistically significant association with C-reactive protein (r = 0.378, P < .001) and liver fibrosis scores (r = 0.401, P < .001), whereas apelin-36 levels showed a modest association with homeostasis model assessment of insulin resistance (r = 0.204, P < .01). After stepwise linear regression analysis, serum vaspin levels were the only independent predictor of liver fibrosis scores in patients with NAFLD (β = 0.37, t = 3.99, P < .01). Serum vaspin levels are raised in patients with NAFLD regardless of potential confounders and represent an independent predictor of liver fibrosis scores. These findings support further investigation of this novel adipokine in metabolic liver diseases.     

Dyslipidemia in patients with nonalcoholic fatty liver disease

Patients with nonalcoholic fatty liver disease (NAFLD) often have dyslipidemia along with other features of metabolic syndrome such as obesity, diabetes mellitus, and hypertension. The dyslipidemia in NAFLD is characterized by increased serum triglycerides, increased small, dense low-density lipoprotein (LDL nontype A) particles, and low high-density lipoprotein (HDL) cholesterol. The pathogenesis of dyslipidemia in NAFLD is not well understood, but it is likely related to hepatic overproduction of the very low-density lipoprotein particles and dysregulated clearance of lipoproteins from the circulation. There is unequivocal evidence that cardiovascular disease is the most common cause of mortality in patients with NAFLD. Aggressive treatment of dyslipidemia plays a critical role in the overall management of patients with NAFLD. Statins are the first-line agents to treat high cholesterol and their dosage should be adjusted based on achieving therapeutic targets and tolerability. Although all statins appear to be effective in improving cholesterol levels in patients with NAFLD, there is more experience with atorvastatin in patients with NAFLD; furthermore, it is the only statin to date to show a reduced cardiovascular morbidity in patients with NAFLD. The risk for serious liver injury from statins is quite rare and patients with NAFLD are not at increased risk for statin hepatotoxicity. Omega-3 fatty acids are perhaps the first choice to treat hypertriglyceridemia because of their safety, tolerability, and efficacy in improving serum triglycerides, as well as their potential to improve liver disease.     

血清细胞角蛋白18诊断非酒精性脂肪性肝病的价值探讨

目的研究血清细胞角蛋白18(CK18)水平诊断非酒精性脂肪性肝病的价值。方法选择93例非酒精性脂肪性肝病(NAFLD)患者和44名年龄与性别相匹配的健康人,检测血清CK18水平,同时测定ALT、AST、GGT、FBG、FINS、TC、TG、HDL、LDL水平,以及血压、身高、体重、腰围(WC)、臀围(HC),并计算腰臀比(WHR)和体重指数(BMI);应用稳态模型评估法计算胰岛素抵抗指数(HOMA-IR)。对其中30例NAFLD患者进行肝组织病理学检查。结果 NAFLD患者血清CK18水平显著高于正常对照组(P<0.001);血清ALT升高的NAFLD患者血清CK18水平(16.38±8.1ng/ml)高于ALT正常组(5.655±4.72 ng/ml),差异有统计学意义(P<0.001);经病理学检查证实的非酒精性脂肪性肝炎患者血清CK18水平(20.93±8.07ng/ml)明显高于非酒精性单纯性脂肪肝患者(7.61±5.51ng/ml),差异有统计学意义(P<0.001);NAFLD患者血清CK18水平与肝脂肪变(r=0.527,P=0.003)、炎症(r=0.662,P<0.001)和纤维化(r=0.715,P<0.001)具有显著的相关性。结论血清CK18水平能反映NAFLD患者肝脏炎症和纤维化程度,因而具有一定的诊断意义。     

非酒精性脂肪性肝病与高尿酸血症

<正>非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)是临床最常见的慢性肝病之一,我国成年人NAFLD患病率超过15%,并且呈现不断上升趋势[1]。近年来,越来越多的研究报道,高尿酸血症与NAFLD密切相关。临床研究发现,NAFLD患者常合并高尿酸血症,并且高尿酸血症显著增加NAFLD的发病风险。动物实验结果表明,高尿酸能引发NAFLD发生,降尿酸干预可有效减轻NAFLD     

Irisin in patients with nonalcoholic fatty liver disease

Objective

Irisin is a recently discovered myokine proposed to increase thermogenesis-related energy expenditure and improve metabolism. We aimed to comparatively evaluate serum irisin levels in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD) vs. controls and study their association with disease severity.

Methods

Fifteen and 16 consecutively enrolled patients with biopsy-proven nonalcoholic simple steatosis (NAFL) and steatohepatitis (NASH), respectively, and 24 lean and 28 obese controls without NAFLD were recruited. Irisin, established adipokines and biochemical tests were measured.

Results

Serum irisin levels were statistically different in obese controls (33.7 ± 2.7 ng/mL; p < 0.001) and patients with NAFL (30.5 ± 1.5 ng/mL; p < 0.001) and NASH (35.8 ± 1.9 ng/mL; p = 0.001) compared with lean controls (47.7 ± 2.0 ng/mL), but were similar among patients with NAFL, NASH and obese controls. This difference remained significant after adjustment for body mass index (or waist circumference), gender, age, insulin resistance (assessed by HOMA-IR or QUICKI), exercise and time since blood collection. Serum leptin and adiponectin, but not irisin, levels were independently from BMI correlated with insulin resistance and cardiometabolic factors. Serum irisin tended to be higher in patients with (36.7 ± 2.4 ng/mL) than without (30.8 ± 1.2 ng/mL; p = 0.02) portal inflammation and independently associated with the latter; these data need to be confirmed by future studies.

Conclusions

Serum irisin levels differ between lean controls and obese controls or NAFLD patients. Despite similar circulating irisin levels between NAFL and NASH groups, irisin may be independently and positively associated with the presence of portal inflammation. Future clinical and mechanistic studies are needed to confirm and extend these data.     

Plasma levels of asymmetric dimethylarginine in patients with biopsy-proven nonalcoholic fatty liver disease

Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) are produced by breakdown of proteins that have been methylated posttranslationally at an arginine residue. Plasma levels of ADMA are elevated in insulin resistance states. Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance and varying degrees of hepatic dysfunction. Because ADMA is metabolized in the liver, we hypothesized that ADMA levels will be high in patients with NAFLD as a consequence of hepatic dysfunction and insulin resistance. Plasma levels of ADMA, SDMA, total homocysteine, glucose, and insulin were measured in nondiabetic patients with biopsy-proven NAFLD (11 steatosis and 24 nonalcoholic steatohepatitis) and 25 healthy subjects. Plasma ADMA levels were significantly higher (P = .029) in patients with biopsy-proven NAFLD (0.43 ± 0.21 μmol/L) compared with controls (0.34 ± 0.10 μmol/L). However, when adjusted for insulin resistance (homeostasis model assessment), the difference between 2 groups was not evident. Plasma SDMA levels were similar in all 3 groups. Plasma levels of ADMA were positively correlated with plasma total homocysteine levels (P = .003). Plasma levels of SDMA were negatively correlated with estimated glomerular filtration rate (P = .016) and positively correlated with plasma total homocysteine levels (P = .003). The ratio of ADMA/SDMA was positively correlated with body mass index (P = .027). Elevated plasma concentrations of ADMA in biopsy-proven NAFLD were primarily related to insulin resistance. Hepatic dysfunction in NAFLD does not appear to make significant contribution to changes in plasma methylarginine levels.     

Plasma apelin levels in subjects with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), one of the most common forms of chronic liver disease, is closely associated with obesity and insulin resistance. Recent studies suggest that apelin, a newly described adipokine, is associated with hyperinsulinemia and inflammation. The aim of the study was to investigate plasma apelin concentrations in biopsy-proven NAFLD patients who had no metabolic confounders and also to search for the association of apelin with adiponectin, body mass index (BMI), and insulin sensitivity. Fifty male patients with NAFLD and 30 healthy male controls were enrolled. Apelin was measured along with BMI, lipids, glucose, insulin, adiponectin, and homeostasis model assessment (HOMA) of insulin resistance indexes. Plasma apelin levels were significantly higher and adiponectin levels were lower in NAFLD patients when compared with the controls (P < .001 and P = .013, respectively). In multivariate analysis adjusted for BMI and HOMA indexes, the differences in apelin and adiponectin disappeared in the 2 groups (P = .3 and P = .1, respectively). In addition, apelin levels were positively correlated with BMI (r = 0.29, P = .05) and HOMA indexes (r = 0.4, P = .008) in subjects with NAFLD. The results of this preliminary study suggest that plasma apelin levels are not altered in nondiabetic and normotensive male subjects with NAFLD.