Department of Environmental Sciences, University of California, Riverside, CA, 92521, United States.
Department of Environmental Sciences, University of California, Riverside, CA, 92521, United States.
Aquat Toxicol. 2024 Nov;276:107121. doi: 10.1016/j.aquatox.2024.107121. Epub 2024 Oct 11.
Pericardial edema - fluid accumulation within the pericardium - is a frequently observed malformation in zebrafish embryo-based chemical toxicity screens. We recently discovered that the severity of triphenyl phosphate (TPHP)-induced pericardial edema was dependent on the ionic strength of exposure media. TPHP is an aryl phosphate ester (APE) widely used as a plasticizer and flame retardant. APEs are characterized by having one or more aryl groups bound to a phosphate center, with TPHP containing only unsubstituted aryl groups. Therefore, the objective of this study was to begin investigating whether, similar to TPHP, pericardial edema induced by other structurally related APEs is dependent on the ionic composition of exposure media. We first mined the peer-reviewed literature to identify other APEs that 1) induced pericardial edema in zebrafish embryos within a minimum of three peer-reviewed publications, and 2) demonstrated a statistically significant induction of pericardial edema in at least 70 % of the studies evaluated. Based on this meta-analysis, we identified four other APEs that caused pericardial edema in zebrafish embryos: isopropylated triphenyl phosphate (IPTPP), cresyl diphenyl phosphate (CDP), tricresyl phosphate (TMPP), and 2-ethylhexyl diphenyl phosphate (EDHPHP). Using TPHP as a positive control and pericardial edema as a readout, we developed concentration-response curves for all four APEs based on static exposure from 24 to 72 h post-fertilization (hpf). We then conducted co-exposures with D-Mannitol (an osmotic diuretic) and exposures within reverse osmosis (RO) water determine whether the ionic composition of exposure media mitigated APE-induced pericardial edema at 72 hpf. Using pericardial edema as an endpoint, the approximate ECs for TPHP (positive control), IPTPP, CDP, TMPP, and EDHPHP were 6.25, 3.125, 3.125, 25, and 100 µM, respectively, based on exposure from 24 to 72 hpf. Interestingly, similar to our findings with TPHP, co-exposure with D-Mannitol and exposure within ion-deficient water significantly mitigated IPTPP- CDP-, TMPP-, and EDHPHP-induced pericardial edema in zebrafish embryos, suggesting that chemically-induced pericardial edema may be 1) dependent on the ionic composition of exposure media and 2) driven by a disruption in osmoregulation across the embryonic epidermis. Therefore, similar to other assay parameters, our findings underscore the need to standardize the osmolarity of exposure media in order to minimize the potential for false positive/negative hits in zebrafish embryo-based chemical toxicity screens conducted around the world.
心包水肿 - 心包内的液体积聚 - 是基于斑马鱼胚胎的化学毒性筛选中经常观察到的畸形。我们最近发现，三苯基磷酸酯 (TPHP) 诱导的心包水肿的严重程度取决于暴露介质的离子强度。TPHP 是一种广泛用作增塑剂和阻燃剂的芳基磷酸酯 (APE)。APE 的特点是一个或多个芳基基团连接到磷酸中心，而 TPHP 只含有未取代的芳基基团。因此，本研究的目的是开始研究是否与 TPHP 类似，其他结构相关的 APE 诱导的心包水肿是否依赖于暴露介质的离子组成。我们首先从同行评议的文献中挖掘出其他 APE，这些 APE 在至少三篇同行评议的出版物中 1) 在斑马鱼胚胎中诱导心包水肿，并且 2) 在评估的研究中至少有 70%显示出心包水肿的统计学显著诱导。基于这项荟萃分析，我们确定了另外四种在斑马鱼胚胎中引起心包水肿的 APE：异丙基三苯基磷酸酯 (IPTPP)、邻苯二甲酸二苯酯 (CDP)、三邻甲苯基磷酸酯 (TMPP) 和 2-乙基己基二苯磷酸酯 (EDHPHP)。我们以 TPHP 作为阳性对照，以心包水肿作为读出，根据受精后 24 至 72 小时 (hpf) 的静态暴露，为所有四种 APE 建立了浓度反应曲线。然后，我们进行了甘露糖醇 (一种渗透利尿剂) 的共暴露和反渗透 (RO) 水中的暴露，以确定暴露介质的离子组成是否在 72 hpf 时减轻了 APE 诱导的心包水肿。使用心包水肿作为终点，基于 24 至 72 hpf 的暴露，TPHP(阳性对照)、IPTPP、CDP、TMPP 和 EDHPHP 的近似 EC 值分别为 6.25、3.125、3.125、25 和 100µM。有趣的是，与我们在 TPHP 中的发现类似，甘露糖醇的共暴露和离子缺乏水中的暴露显著减轻了 IPTPP-CD-TMPP-和 EDHPHP 在斑马鱼胚胎中诱导的心包水肿，这表明化学诱导的心包水肿可能 1) 依赖于暴露介质的离子组成，2) 由胚胎表皮的渗透压紊乱驱动。因此，与其他测定参数类似，我们的发现强调需要标准化暴露介质的渗透压，以最大程度地减少世界各地基于斑马鱼胚胎的化学毒性筛选中潜在的假阳性/阴性结果。
