Honigbaum Stefany, Zhu Qingfeng, Layman Andrew, Anders Robert A, Schwarz Kathleen B
Department of Pediatrics.
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD.
J Pediatr Gastroenterol Nutr. 2019 Sep;69(3):344-350. doi: 10.1097/MPG.0000000000002414.
Biliary atresia (BA) is characterized by rapidly progressive inflammation and fibrosis of the biliary tract, which usually progresses despite surgical intervention (Kasai hepatoportoenterostomy). Lysyl oxidase-like (LOXL2) is an extracellular matrix enzyme that catalyzes the cross-linking of fibrillar collagen and elastin and is thought to play a crucial role in tissue fibrosis; anti-LOXL2 drugs have been shown to be antifibrotic in animals.
The aim of the study was to investigate the presence of LOXL2 in BA livers and hepatic and extrahepatic control tissues.
Liver wedge biopsies from infants with BA (n = 20) were obtained at Kasai, and were compared with non-BA livers (n = 20). Liver fibrosis was scored using the Ishak scale, and immunohistochemistry was performed using a commercially available polyclonal anti-LOXL2 antibody. The expression of LOXL2 was scored for intensity and for distribution of bile duct staining by a pathologist blinded to the diagnosis. Staining of LOXL2 in pediatric control tissue, muscle (n = 5), heart (n = 5), and bone (n = 10) was performed.
Tissue from patients with BA abundantly expressed LOXL2 (intensity score 2.0 vs 1.4 [P ≤ 0.001]) for non-BA and distribution of bile duct-staining score of 3.0 versus 2.8 (P = 0.001) for non-BA. Fibrosis score of all BA samples was 4.2 versus 3.1 for non-BA. Nonhepatic pediatric tissue displayed minimal to no LOXL2 staining.
There is significant overexpression of LOXL2 in BA hepatic tissue with minimal expression in extrahepatic tissue. The over expression noted in human hepatic tissue at Kasai suggests the rationale for further investigation of anti-LOXL2 therapeutics in BA.
胆道闭锁（BA）的特征是胆道迅速进行性炎症和纤维化，即使进行手术干预（Kasai肝门肠吻合术）通常仍会进展。赖氨酰氧化酶样蛋白2（LOXL2）是一种细胞外基质酶，可催化纤维状胶原蛋白和弹性蛋白的交联，被认为在组织纤维化中起关键作用；抗LOXL2药物在动物实验中已显示出抗纤维化作用。
本研究旨在调查BA肝脏以及肝脏和肝外对照组织中LOXL2的存在情况。
在Kasai手术时获取20例BA婴儿的肝楔形活检组织，并与20例非BA肝脏进行比较。使用Ishak评分系统对肝纤维化进行评分，并使用市售的多克隆抗LOXL2抗体进行免疫组织化学检测。由对诊断不知情的病理学家对LOXL2的表达强度和胆管染色分布进行评分。对儿科对照组织、肌肉（n = 5）、心脏（n = 5）和骨骼（n = 10）进行LOXL2染色。
BA患者的组织中LOXL2大量表达（强度评分2.0，非BA为1.4 [P≤0.001]），胆管染色分布评分3.0，非BA为2.8（P = 0.001）。所有BA样本的纤维化评分为4.2，非BA为3.1。非肝脏儿科组织显示LOXL2染色极少或无染色。
BA肝组织中LOXL2显著过表达，肝外组织中表达极少。在Kasai手术中人类肝组织中观察到的过表达提示了进一步研究抗LOXL2疗法治疗BA的理论依据。
