Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.
Gastroenterology. 2020 Sep;159(3):1068-1084.e2. doi: 10.1053/j.gastro.2020.05.080. Epub 2020 Jun 4.
BACKGROUND & AIMS: Extrahepatic biliary atresia (BA) is a pediatric liver disease with no approved medical therapy. Recent studies using human samples and experimental modeling suggest that glutathione redox metabolism and heterogeneity play a role in disease pathogenesis. We sought to dissect the mechanistic basis of liver redox variation and explore how other stress responses affect cholangiocyte injury in BA.
We performed quantitative in situ hepatic glutathione redox mapping in zebrafish larvae carrying targeted mutations in glutathione metabolism genes and correlated these findings with sensitivity to the plant-derived BA-linked toxin biliatresone. We also determined whether genetic disruption of HSP90 protein quality control pathway genes implicated in human BA altered biliatresone toxicity in zebrafish and human cholangiocytes. An in vivo screening of a known drug library was performed to identify novel modifiers of cholangiocyte injury in the zebrafish experimental BA model, with subsequent validation.
Glutathione metabolism gene mutations caused regionally distinct changes in the redox potential of cholangiocytes that differentially sensitized them to biliatresone. Disruption of human BA-implicated HSP90 pathway genes sensitized zebrafish and human cholangiocytes to biliatresone-induced injury independent of glutathione. Phosphodiesterase-5 inhibitors and other cyclic guanosine monophosphate signaling activators worked synergistically with the glutathione precursor N-acetylcysteine in preventing biliatresone-induced injury in zebrafish and human cholangiocytes. Phosphodiesterase-5 inhibitors enhanced proteasomal degradation and required intact HSP90 chaperone.
Regional variation in glutathione metabolism underlies sensitivity to the biliary toxin biliatresone and may account for the reported association between BA transplant-free survival and glutathione metabolism gene expression. Human BA can be causatively linked to genetic modulation of protein quality control. Combined treatment with N-acetylcysteine and cyclic guanosine monophosphate signaling enhancers warrants further investigation as therapy for BA.
肝外胆道闭锁（BA）是一种儿科肝脏疾病，目前尚无批准的医学疗法。最近的研究使用人体样本和实验模型表明，谷胱甘肽氧化还原代谢和异质性在疾病发病机制中起作用。我们试图剖析肝脏氧化还原变化的机制基础，并探索其他应激反应如何影响 BA 中的胆管细胞损伤。
我们在携带谷胱甘肽代谢基因靶向突变的斑马鱼幼虫中进行了定量原位肝谷胱甘肽氧化还原图谱绘制，并将这些发现与对植物源性 BA 相关毒素胆比妥雷酮的敏感性相关联。我们还确定了人类 BA 中涉及 HSP90 蛋白质量控制途径基因的遗传破坏是否改变了斑马鱼和人胆管细胞中的胆比妥雷酮毒性。对已知药物库进行了体内筛选，以鉴定在斑马鱼实验性 BA 模型中胆管细胞损伤的新型调节剂，随后进行了验证。
谷胱甘肽代谢基因突变导致胆管细胞的氧化还原电位在区域上发生了不同的变化，使它们对胆比妥雷酮的敏感性不同。人类 BA 涉及的 HSP90 途径基因的破坏使斑马鱼和人胆管细胞对胆比妥雷酮诱导的损伤敏感，而与谷胱甘肽无关。磷酸二酯酶-5 抑制剂和其他环鸟苷单磷酸信号激活剂与谷胱甘肽前体 N-乙酰半胱氨酸协同作用，可预防斑马鱼和人胆管细胞中的胆比妥雷酮诱导的损伤。磷酸二酯酶-5 抑制剂增强了蛋白酶体降解，并且需要完整的 HSP90 伴侣。
谷胱甘肽代谢的区域变化是对胆道毒素胆比妥雷酮敏感性的基础，这可能解释了报道的 BA 无移植生存与谷胱甘肽代谢基因表达之间的关联。人类 BA 可以与蛋白质质量控制的遗传调节因果相关。N-乙酰半胱氨酸和环鸟苷单磷酸信号增强剂的联合治疗值得进一步研究，作为 BA 的治疗方法。
