20 Years of fish immunotoxicology – what we know and where we are

Despite frequent field observations of impaired immune response and increased disease incidence in contaminant-exposed wildlife populations, immunotoxic effects are rarely considered in ecotoxicological risk assessment. The aim of this study was to review the literature on immunotoxic effects of chemicals in fish to quantitatively evaluate (i) which experimental approaches were used to assess immunotoxic effects, (ii) whether immune markers exist to screen for potential immunotoxic activities of chemicals, and (iii) how predictive those parameters are for adverse alterations of fish immunocompetence and disease resistance. A total of 241 publications on fish immunotoxicity were quantitatively analyzed. The main conclusions included: (i) To date, fish immunotoxicology focused mainly on innate immune responses and immunosuppressive effects. (ii) In numerous studies, the experimental conditions are poorly documented, as for instance age or sex of the fish or the rationale for the selected exposure conditions is often missing. (iii) Although a broad variety of parameters were used to assess immunotoxicity, the rationale for the choice of measured parameters was often not given, remaining unclear how they link to the suspected immunotoxic mode of action of the chemicals. (iv) At the current state of knowledge, it is impossible to identify a set of immune parameters that could reliably screen for immunotoxic potentials of chemicals. (v) Similarly, in fish immunotoxicology there is insufficient understanding of how and when chemical-induced modulations of molecular/cellular immune changes relate to adverse alterations of fish immunocompetence, although this would be crucial to include immunotoxicity in ecotoxicological risk assessment.

尽管野外频繁观测到暴露于污染物的野生动物种群存在免疫应答受损、疾病发生率升高的现象，但生态毒理学风险评估（ecotoxicological risk assessment）中极少纳入免疫毒性效应（immunotoxic effects）的考量。本研究旨在梳理鱼类化学品免疫毒性效应的相关文献，以定量评估三方面内容：(i) 用于评估免疫毒性效应的实验方法有哪些；(ii) 是否存在可用于筛选化学品潜在免疫毒性活性的免疫标志物（immune markers）；(iii) 各项参数对鱼类免疫能力与疾病抵抗能力的不良改变的预测性能如何。本研究共计定量分析了241篇鱼类免疫毒性相关文献，主要结论如下：(i) 截至当前，鱼类免疫毒理学（fish immunotoxicology）的研究主要聚焦于固有免疫应答（innate immune responses）与免疫抑制效应（immunosuppressive effects）。(ii) 众多研究的实验条件记录不完善，例如鱼类的年龄、性别信息，或是所选暴露条件的依据往往缺失。(iii) 尽管研究中使用了种类繁多的参数来评估免疫毒性，但多数研究未阐明所选测量参数的选择依据，因此难以明确这些参数与疑似的化学品免疫毒性作用模式存在何种关联。(iv) 就现有认知水平而言，无法确定一套可可靠筛选化学品免疫毒性潜力的免疫参数集合。(v) 同理，尽管将免疫毒性纳入生态毒理学风险评估至关重要，但目前鱼类免疫毒理学领域对化学物质诱导的免疫分子/细胞改变的调控如何与鱼类免疫能力的不良改变相关联，以及此类关联何时发生，仍缺乏足够的认识。