Ribeiro Paulo S, Cortez-Pinto Helena, Solá Susana, Castro Rui E, Ramalho Rita M, Baptista Amélia, Moura Miguel C, Camilo Maria E, Rodrigues Cecília M P
Centro de Patogénese Molecular, Faculty of Pharmacy, University of Lisbon, Lisbon 1600 083, Portugal.
Am J Gastroenterol. 2004 Sep;99(9):1708-17. doi: 10.1111/j.1572-0241.2004.40009.x.
The increasing incidence of nonalcoholic (NASH) and alcoholic steatohepatitis (ASH), associated with lack of effective treatment, has prompted intensive studies on disease pathogenesis. Apoptosis is recognized as common in liver injury and may also contribute to tissue inflammation, fibrogenesis, and development of cirrhosis. In this study, we identified mechanisms of apoptosis induction in human steatohepatitis, and evaluated potential associations between apoptosis, liver pathology, and clinical presentation in NASH and ASH.
Hepatocyte apoptosis was evaluated by the TUNEL assay in 20 patients with NASH (all ambulatory), 40 with ASH (20 ambulatory, 20 hospitalized), and 20 controls. Liver biopsies were also graded for inflammation and fibrosis. Immunohistochemistry was performed for death receptors (Fas and TNF-R1), activated caspase-3, NF-kappaB p65, antiapoptotic Bcl-2 protein, and uncoupling protein 2 (UCP-2).
TUNEL-positive hepatocytes were markedly increased in NASH (p < 0.05) and ASH (p < 0.01). Similar results were obtained for activated caspase-3, confirming the occurrence of apoptosis. The Fas receptor was upregulated in ASH, especially in hospitalized patients (p < 0.01), whereas TNF-R1 was expressed both in NASH and ASH (p < 0.01). In addition, patients with ASH showed a remarkable expression of active NF-kappaB, as compared to NASH and controls (p < 0.01). Degrees of inflammation and fibrosis correlated with NF-kappaB p65 expression, which in turn coincided with apoptosis albeit Bcl-2 and UCP-2 expression.
Liver injury in NASH and ASH is associated with increased hepatocyte apoptosis mediated by death receptors. Further, apoptosis correlates with active NF-kappaB expression, and disease severity. This potential mechanistic link might provide multiple interesting targets for therapeutic intervention.
非酒精性脂肪性肝炎（NASH）和酒精性脂肪性肝炎（ASH）的发病率不断上升，且缺乏有效的治疗方法，这促使人们对疾病发病机制进行深入研究。细胞凋亡在肝损伤中很常见，也可能导致组织炎症、纤维化和肝硬化的发展。在本研究中，我们确定了人类脂肪性肝炎中细胞凋亡诱导的机制，并评估了NASH和ASH中细胞凋亡、肝脏病理和临床表现之间的潜在关联。
采用TUNEL法对20例NASH患者（均为门诊患者）、40例ASH患者（20例门诊患者，20例住院患者）和20例对照者的肝细胞凋亡情况进行评估。同时对肝活检组织进行炎症和纤维化分级。对死亡受体（Fas和TNF-R1）、活化的半胱天冬酶-3、核因子κB p65、抗凋亡Bcl-2蛋白和解偶联蛋白2（UCP-2）进行免疫组织化学检测。
NASH组（p < 0.05）和ASH组（p < 0.01）TUNEL阳性肝细胞显著增加。活化的半胱天冬酶-3也得到了类似结果，证实了细胞凋亡的发生。Fas受体在ASH中上调，尤其是在住院患者中（p < 0.01），而TNF-R1在NASH和ASH中均有表达（p < 0.01）。此外，与NASH组和对照组相比，ASH患者中活性核因子κB的表达显著增加（p < 0.01）。炎症和纤维化程度与核因子κB p65表达相关，而核因子κB p65表达又与细胞凋亡一致，尽管有Bcl-2和UCP-2表达。
NASH和ASH中的肝损伤与死亡受体介导的肝细胞凋亡增加有关。此外，细胞凋亡与活性核因子κB表达及疾病严重程度相关。这种潜在的机制联系可能为治疗干预提供多个有趣的靶点。
