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首页> 美国卫生研究院文献>Pathogens >Fasciola hepatica: Histology of the Reproductive Organs and Differential Effects of Triclabendazole on Drug-Sensitive and Drug-Resistant Fluke Isolates and on Flukes from Selected Field Cases
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Fasciola hepatica: Histology of the Reproductive Organs and Differential Effects of Triclabendazole on Drug-Sensitive and Drug-Resistant Fluke Isolates and on Flukes from Selected Field Cases

机译：Fasciola hepatica：生殖器官的组织学和三氯苯达唑对药物敏感性和抗药性吸虫分离株以及某些田间病例的吸虫的差异作用

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摘要

This review summarises the findings of a series of studies in which the histological changes, induced in the reproductive system of Fasciola hepatica following treatment of the ovine host with the anthelmintic triclabendazole (TCBZ), were examined. A detailed description of the normal macroscopic arrangement and histological features of the testes, ovary, vitelline tissue, Mehlis’ gland and uterus is provided to aid recognition of the drug-induced lesions, and to provide a basic model to inform similar toxicological studies on F. hepatica in the future. The production of spermatozoa and egg components represents the main energy consuming activity of the adult fluke. Thus the reproductive organs, with their high turnover of cells and secretory products, are uniquely sensitive to metabolic inhibition and sub-cellular disorganisation induced by extraneous toxic compounds. The flukes chosen for study were derived from TCBZ-sensitive (TCBZ-S) and TCBZ-resistant (TCBZ-R) isolates, the status of which had previously been proven in controlled clinical trials. For comparison, flukes collected from flocks where TCBZ resistance had been diagnosed by coprological methods, and from a dairy farm with no history of TCBZ use, were also examined. The macroscopic arrangement of the reproductive system in flukes was studied using catechol/carmine stained whole mounts, and the histology of the main organs was examined using conventional haematoxylin-eosin stained sections. Validation of apoptosis in the fluke sections was carried out using an in situ hybridisation method designed to label endonuclease-induced DNA strand breaks. In TCBZ-S flukes exposed to TCBZ metabolites for 24–96 h in vivo, but not in TCBZ-R flukes, those tissues where active meiosis and/or mitosis occurred (testis, ovary, and vitelline follicles), were found to display progressive loss of cell content. This was due to apparent failure of cell division to keep pace with expulsion of the mature or effete products. Further, actively dividing cell types tended to become individualised, rounded and condensed, characteristic of apoptotic cell death. In the treated TCBZ-S flukes, strong positive labelling indicating apoptosis was associated with the morphologically abnormal cells undergoing mitosis or meiosis in the testis, ovary and vitelline follicles. In treated flukes from field outbreaks of suspected TCBZ-R fasciolosis, no significant histological changes were observed, nor was there any positive labelling for apotosis. On the other hand, sections of TCBZ treated flukes derived from a field case of fasciolosis where TCBZ resistance was not suspected displayed severe histological lesions, and heavy positive labelling for apoptosis. The triggering of apoptosis is considered to be related to failure of spindle formation at cell division, supporting the contention that TCBZ inhibits microtubule formation. In treated TCBZ-S flukes, protein synthesis and transport was apparently inhibited in the Mehlis’ secretory cells, perhaps due to energy uncoupling or to microtubule defects. In the uterus, successful formation of shelled eggs represents the culmination of a complex sequence of cytokinetic, cytological and synthetic activity involving the vitelline follicles, the ovary and the Mehlis’ gland. Histological evidence indicating failure of ovigenesis in TCBZ-S flukes was evident from as early as 24 h post-treatment onwards. Light labelling for apoptosis was associated with the testis of untreated Cullompton (TCBZ-S) and Sligo type 2 (TCBZ-R) flukes, which exhibit abnormal spermatogenesis and spermiogenesis, respectively. This was attributed to apoptosis and to heterophagy of effete germ line cells by the sustentacular tissue. The studies summarised in this review illustrate the potential utility of histological techniques for conveniently screening representative samples of flukes in field trials designed to validate instances of drug resistance. Histology can also be used to test the efficacy of new products against known drug-resistant and drug-susceptible fluke isolates. The account also provides reference criteria for drug-induced histopathological changes in fluke reproductive structures, examination of which may supplement and augment conventional coprological testing, and aid interpretation of TEM findings.
机译：这篇综述总结了一系列研究的发现，在这些研究中，研究了用蠕虫性三苯达唑（TCBZ）处理绵羊宿主后，在Fasciola hepica的生殖系统中诱导的组织学变化。详细描述了睾丸，卵巢，卵黄组织，Mehlis腺和子宫的正常宏观排列和组织学特征，以帮助识别药物引起的病变，并提供了基础模型，为类似的F毒理学研究提供依据未来的肝炎。精子和卵子成分的生产代表了成年the虫的主要能量消耗活动。因此，生殖器官及其细胞和分泌产物的高周转率，对由外来有毒化合物引起的代谢抑制和亚细胞分解异常敏感。选择用于研究的吸虫来自对TCBZ敏感的（TCBZ-S）和对TCBZ耐药的（TCBZ-R）分离株，其状态先前已在对照临床试验中得到证明。为了进行比较，还检查了从通过粪细菌学方法诊断出对TCBZ有抗性的鸡群以及没有使用TCBZ的奶牛场收集的禽肉。使用邻苯二酚/胭脂红染色的整块动物研究了吸虫的生殖系统的宏观排列，并使用常规的苏木精-伊红染色切片检查了主要器官的组织学。使用原位杂交方法对the节切片中的细胞凋亡进行验证，该方法旨在标记核酸内切酶诱导的DNA链断裂。在体内暴露于TCBZ代谢产物24-96 h的TCBZ-S吸虫中，但在TCBZ-R吸虫中则没有，发现发生活跃减数分裂和/或有丝分裂的组织（睾丸，卵巢和卵黄卵泡）细胞含量的损失。这是由于细胞分裂明显不能跟上成熟或有效产品的排出。此外，主动分裂的细胞类型趋向于成为凋亡细胞死亡的特征的个体化，圆形和浓缩。在处理过的TCBZ-S吸虫中，强阳性标记表明凋亡与睾丸，卵巢和卵黄卵泡中发生有丝分裂或减数分裂的形态异常细胞有关。在可疑的TCBZ-R筋膜炎暴发的田间暴发的已处理吸虫中，未观察到明显的组织学变化，也未见任何阳性标记。另一方面，TCBZ处理的吸虫的切片来源于未曾怀疑为TCBZ抗药性的fasioolosis现场病例，显示出严重的组织学损伤，并且细胞凋亡的阳性标记很重。凋亡的触发被认为与细胞分裂中纺锤体形成的失败有关，这支持了TCBZ抑制微管形成的观点。在处理过的TCBZ-S吸虫中，Mehlis分泌细胞中的蛋白质合成和运输明显受到抑制，这可能是由于能量解偶联或微管缺陷引起的。在子宫中，带壳卵的成功形成代表了一系列复杂的细胞动力学，细胞学和合成活性序列，涉及卵黄卵泡，卵巢和Mehlis腺。组织学证据表明，早在治疗后24小时起，就可以发现TCBZ-S吸虫卵生失败。凋亡的光标记与未经处理的Cullompton（TCBZ-S）和Sligo 2型（TCBZ-R）吸虫的睾丸相关，它们分别表现出异常的精子发生和精子发生。这归因于细胞的凋亡和南芥属组织引起的胚芽种系细胞的异噬。在这篇综述中总结的研究表明，组织学技术在田间试验中方便地筛选代表性的吸虫样本具有潜在的实用性，旨在验证耐药性实例。组织学还可以用于测试新产品对已知的耐药和易感吸虫分离株的功效。该帐户还提供了吸虫吸虫生殖结构中药物引起的组织病理学变化的参考标准，对其进行检查可以补充和增强常规的阴道镜检查，并有助于解释TEM结果。

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