Metabolic, hormonal, oxidative, and inflammatory factors in pediatric obesity-related liver disease

OBJECTIVE: To examine the role of metabolic, hormonal, oxidative, and inflammatory factors in pediatric obesity-related liver disease. STUDY DESIGN: In 50 obese children (age 7 to 14 years) with (n = 20, group 1) or without (n = 30, group 2) hypertransaminasemia and ultrasonographic liver brightness, we studied insulin resistance (fasting glucose/insulin ratio [FGIR]) and serum levels of leptin, iron, transferrin, ferritin, C-reactive protein (CRP), white blood cell (WBC) count, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, C282Y and H63D mutations, and erythrocytic glutathione peroxidase (GPX) activity. RESULTS: FGIR (6.7 +/- 4.1 vs 9.2 +/- 5.2; P = .02), serum ferritin (88.8 +/- 36.0 vs 39.9 +/- 24.0 ng/mL; P = .0001), serum CRP (5.4 +/- 6.0 vs 1.1 +/- 1.6 mg/dL; P = 0.004), and GPX (8.4 +/- 0.9 vs 5.0 +/- 0.5 U/g Hb; P = .05) were significantly higher and more frequently deranged in group 1 than in group 2. FGIR, ferritin, and CRP values were simultaneously deranged in 41% of the group 1 patients and in none of the group 2 patients ( P = .098). Serum leptin, iron, and transferrin, WBC, TNF-alpha, IL-6, and C282Y and H63D mutations were similar in the 2 groups. CONCLUSIONS: Insulin resistance, oxidative stress, and low-grade systemic inflammatory status are implicated in pediatric obesity-related liver disease. These findings may be useful in planning pathophysiologically based therapeutic trials for hepatopathic obese children who are unable to follow hypocaloric diets.     

Utility of transient elastography (fibroscan) and impact of bariatric surgery on nonalcoholic fatty liver disease (NAFLD) in morbidly obese patients

Background

Controlled attenuation parameter (CAP) is a novel, noninvasive technique for assessing hepatic steatosis. However, its role in morbidly obese individuals is unclear. The effect of bariatric surgery on inflammation and fibrosis needs to be explored.

The natural history of nonalcoholic fatty liver disease: a population-based cohort study

BACKGROUND & AIMS: The natural history of nonalcoholic fatty liver disease (NAFLD) in the community remains unknown. We sought to determine survival and liver-related morbidity among community-based NAFLD patients. METHODS: Four hundred twenty patients diagnosed with NAFLD in Olmsted County, Minnesota, between 1980 and 2000 were identified using the resources of the Rochester Epidemiology Project. Medical records were reviewed to confirm diagnosis and determine outcomes up to 2003. Overall survival was compared with the general Minnesota population of the same age and sex. RESULTS: Mean (SD) age at diagnosis was 49 (15) years; 231 (49%) were male. Mean follow-up was 7.6 (4.0) years (range, 0.1-23.5) culminating in 3192 person-years follow-up. Overall, 53 of 420 (12.6%) patients died. Survival was lower than the expected survival for the general population (standardized mortality ratio, 1.34; 95% CI, 1.003-1.76; P = .03). Higher mortality was associated with age (hazard ratio per decade, 2.2; 95% CI, 1.7-2.7), impaired fasting glucose (hazard ratio, 2.6; 95% CI, 1.3-5.2), and cirrhosis (hazard ratio, 3.1, 95% CI, 1.2-7.8). Liver disease was the third leading cause of death (as compared with the thirteenth leading cause of death in the general Minnesota population), occurring in 7 (1.7%) subjects. Twenty-one (5%) patients were diagnosed with cirrhosis, and 13 (3.1%) developed liver-related complications, including 1 requiring transplantation and 2 developing hepatocellular carcinoma. CONCLUSIONS: Mortality among community-diagnosed NAFLD patients is higher than the general population and is associated with older age, impaired fasting glucose, and cirrhosis. Liver-related death is a leading cause of mortality, although the absolute risk is low.     

Liver mitochondrial function and redox status in an experimental model of non-alcoholic fatty liver disease induced by monosodium L-glutamate in rats

The purpose of this work was to determine if mitochondrial dysfunction is involved in the development of non-alcoholic fatty liver disease (NAFLD). Using a model of obesity induced by the neonatal treatment of rats with monosodium l-glutamate (MSG), several parameters of liver mitochondrial function and their impact on liver redox status were evaluated. Specifically, fatty acid β-oxidation, oxidative phosphorylation and Ca²⁺-induced mitochondrial permeability transition were assessed in isolated liver mitochondria, and reduced glutathione (GSH), linked thiol contents and the activities of several enzymes involved in the control of redox status were measured in the liver homogenate. Our results demonstrate that liver mitochondria from MSG-obese rats exhibit a higher β-oxidation capacity and an increased capacity for oxidising succinate, without loss in the efficiency of oxidative phosphorylation. Also, liver mitochondria from obese rats were less susceptible to the permeability transition pore (PTP) opening induced by 1.0 μM CaCl₂. Cellular levels of GSH were unaffected in the livers from the MSG-obese rats, whereas reduced linked thiol contents were increased. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione peroxidase were increased, while catalase activity was unaffected and superoxide dismutase activity was reduced in the livers from the MSG-obese rats. In this model of obesity, liver fat accumulation is not a consequence of mitochondrial dysfunction. The enhanced glucose-6-phosphate dehydrogenase activity observed in the livers of MSG-obese rats could be associated with liver fat accumulation and likely plays a central role in the mitochondrial defence against oxidative stress.     

脂联素与非酒精性脂肪肝肝纤维化及胰岛素抵抗的关系

目的：研究脂联素水平与非酒精性脂肪肝（NAFLD）患者肝纤维化指标及胰岛素抵抗指数（IRI）的关系。方法：采用ELISA法检测NAFLD患者和正常对照组的脂联素水平及Ⅲ型前胶原（PCⅢ）、透明质酸（HA）、Ⅳ型胶原（CⅣ）、层黏蛋白（LN）水平,采用稳态模式胰岛素抵抗指数（HOMA IRI）评估胰岛素抵抗。结果：NAFLD组脂联素水平显著低于对照组,胰岛素抵抗指数与肝纤维化指标显著高于对照组（P〈0.05）,IRI与PCⅢ、PCⅣ、HA和LN呈显著正相关（P〈0.05）,脂联素水平与WHR、BMI、FBG、Tg、FINS、HOMA-IRI、PCⅢ、PCⅣ、HA和LN呈显著负相关（P〈0.01或〈0.05）。结论：NAFLD患者血清脂联素水平降低,脂联素的表达在NAFLD患者肝纤维化与胰岛素抵抗进程中可能起重要作用。     

非酒精性脂肪性肝病发病机制的研究进展

非酒精性脂肪性肝病（NAFLD）是指与过量饮酒无关的临床综合征,主要病理改变包括肝细胞弥漫性脂肪变性和脂肪堆积。NAFLD动物模型表现出显著的肝脏微循环障碍,关于其形成机制,被广为接受的为＂二次打击＂学说。该学说认为肥胖、胰岛素抵抗等因素作为＂第一次打击＂,导致肝脏中脂质堆积,形成单纯性脂肪肝,增加了＂第二次打击＂造成的肝脏损伤的易感性,这些因素包括炎症、枯否细胞功能障碍、氧化应激、线粒体障碍、脂肪因子调节紊乱等,导致非酒精性脂肪性肝炎甚至纤维化等更严重疾病的发生。     

Molecular evolution of adiponectin in Carnivora and its mRNA expression in relation to hepatic lipidosis

Adiponectin is a novel adipocyte-derived hormone with low circulating concentrations and/or mRNA expression in obesity and non-alcoholic fatty liver disease (NAFLD). The adiponectin mRNA of several Carnivora species was sequenced to enable further gene expression studies in this clade with potential experimental species to examine the connections of hypoadiponectinemia to hepatic lipidosis. In addition, adiponectin mRNA expression was studied in the retroperitoneal fat of the American mink (Neovison vison), as hepatic lipidosis with close similarities to NAFLD can be rapidly induced to the species by fasting. The mRNA expression was determined after overnight-7 d of food deprivation and 28 d of re-feeding and correlated to the liver fat %. The homologies between the determined carnivoran mRNA sequences and that of the domestic dog were 92.2-99.1%. As the mRNA expression was not affected by short-term fasting and did not correlate with the liver fat %, there seems to be no clear connection between adiponectin and the development of lipidosis in the American mink. In the future, the obtained sequences can be utilized in further studies of adiponectin expression in comparative endocrinology.