Gupta Kapish, Chen Dongning, Wells Rebecca G
Division of Gastroenterology and Hepatology, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Center for Engineering MechanoBiology, University of Pennsylvania, Philadelphia, PA, USA.
JHEP Rep. 2024 Sep 12;7(1):101218. doi: 10.1016/j.jhepr.2024.101218. eCollection 2025 Jan.
BACKGROUND & AIMS: Biliary atresia is a fibrosing cholangiopathy affecting neonates that is thought to result from a prenatal environmental insult to the bile duct. Biliatresone, a plant toxin with an α-methylene ketone group, was previously implicated in biliary atresia in Australian livestock, but is found in a limited location and is unlikely to be a significant human toxin. We hypothesized that other unsaturated carbonyl compounds, some with the potential for significant human exposure, might also be biliary toxins.
We focused on the family of microcystins, cyclic peptide toxins from blue-green algae that are found worldwide, particularly during harmful algal blooms. We used primary extrahepatic cholangiocyte spheroids and extrahepatic bile duct explants from both neonatal [a total of 86 postnatal day (P) 2 mouse pups and 18 P2 rat pups (n = 8-10 per condition for both species)] and adult rodents [a total of 31 P15-18 mice (n = 10 or 11 per condition)] to study the biliary toxicity of microcystins and potential mechanisms involved.
Results showed that 400 nM microcystin (MC)-RR, but not six other microcystins or the related algal toxin nodularin, caused >80% lumen closure in cell spheroids made from extrahepatic cholangiocytes isolated from 2-3-day-old mice ( <0.0001). By contrast, 400 nM MC-RR resulted in less than an average 5% lumen closure in spheroids derived from neonatal intrahepatic cholangiocytes or cells from adult mice ( = 0.4366). In addition, MC-RR caused occlusion of extrahepatic bile duct explants from 2-day-old mice ( <0.0001), but not 18-day-old mice. MC-RR also caused a 2.3-times increase in reactive oxygen species in neonatal cholangiocytes ( <0.0001), and treatment with -acetyl cysteine partially prevented microcystin-RR-induced lumen closure ( = 0.0004), suggesting a role for redox homeostasis in its mechanism of action.
We identified MC-RR as a selective neonatal extrahepatic cholangiocyte toxin and suggest that it acts by increasing redox stress.
The plant toxin biliatresone causes a biliary atresia-like disease in livestock and vertebrate animal model systems. We tested the widespread blue-green algal toxin, microcystin-RR, another highly electrophilic unsaturated carbonyl compound that is released during harmful algal blooms, and found that it was also a biliary toxin with specificity for neonatal extrahepatic cholangiocytes. This work should drive further animal studies and, ultimately, studies to determine whether human exposure to microcystin-RR causes biliary atresia.
胆道闭锁是一种影响新生儿的纤维性胆管病，被认为是由产前环境对胆管的损害所致。双环缩肽毒素是一种含有α - 亚甲基酮基团的植物毒素，此前在澳大利亚家畜的胆道闭锁中被认为有牵连，但它的分布地点有限，不太可能是一种对人类有重大影响的毒素。我们推测，其他不饱和羰基化合物，其中一些有可能大量接触人类，也可能是胆道毒素。
我们聚焦于微囊藻毒素家族，这是一类来自蓝藻的环肽毒素，在全球范围内都有发现，尤其是在有害藻华期间。我们使用了新生[共86只出生后第2天（P）的小鼠幼崽和18只P2大鼠幼崽（两种动物每种条件下n = 8 - 10）]和成年啮齿动物[共31只P15 - 18小鼠（每种条件下n = 10或11）]的肝外胆管细胞球和肝外胆管外植体，来研究微囊藻毒素的胆道毒性及其潜在机制。
结果显示，400 nM微囊藻毒素（MC）-RR可导致从2 - 3日龄小鼠分离的肝外胆管细胞制成的细胞球中管腔闭合>80%，而其他六种微囊藻毒素或相关藻毒素节球藻毒素则不会（P < 0.0001）。相比之下，400 nM MC - RR导致新生肝内胆管细胞或成年小鼠细胞来源的球状体中管腔平均闭合不到5%（P = 0.4366）。此外，MC - RR导致2日龄小鼠的肝外胆管外植体闭塞（P < 0.0001），但对18日龄小鼠则无此作用。MC - RR还使新生胆管细胞中的活性氧增加了2.3倍（P < 0.0001），用N - 乙酰半胱氨酸处理可部分预防微囊藻毒素 - RR诱导的管腔闭合（P = 0.0004），这表明氧化还原稳态在其作用机制中起作用。
我们确定MC - RR是一种选择性的新生肝外胆管细胞毒素，并表明它通过增加氧化还原应激起作用。
植物毒素双环缩肽毒素在牲畜和脊椎动物模型系统中可引起类似胆道闭锁的疾病。我们测试了广泛存在的蓝藻毒素微囊藻毒素 - RR，这是另一种在有害藻华期间释放的高亲电不饱和羰基化合物，发现它也是一种对新生肝外胆管细胞具有特异性的胆道毒素。这项工作应推动进一步的动物研究，并最终推动研究以确定人类接触微囊藻毒素 - RR是否会导致胆道闭锁。
