BACKGROUND Organophosphate esters (OPEs) are flame retardants and plasticizers used in consumer products. OPEs are found ubiquitously throughout the environment with high concentrations in indoor house dust. Exposure to individual OPEs is associated with immune dysfunction, particularly in macrophages. However, OPEs exist as complex mixtures and the effects of environmentally relevant mixtures on the immune system have not been investigated. OBJECTIVES The objectives of this study were to evaluate the toxicity of an environmentally relevant mixture of OPEs that models Canadian house dust on macrophages using phenotypic and functional assessments in vitro. METHODS High-content live-cell fluorescent imaging for phenotypic biomarkers of toxicity in THP-1 macrophages treated with the OPE mixture was undertaken. We used confocal microscopy and cholesterol analysis to validate and expand on the observed OPE-induced lipid phenotype. Then, we used flow cytometry and live-cell imaging to conduct functional tests and uncover mechanisms of OPE-induced phagocytic suppression. Finally, we validated our THP-1 findings in human primary peripheral blood mononuclear cells (hPBMC) derived macrophages. RESULTS Exposure to non-cytotoxic dilutions of the OPE mixture resulted in higher oxidative stress and disrupted lysosome and lipid homeostasis in THP-1 and primary macrophages. We further observed that phagocytosis of apoptotic cells in THP-1 and primary macrophages was lower in OPE-exposed cells vs. controls. In THP-1 macrophages, phagocytosis of both Gram-positive and Gram-negative bacteria was also lower in OPE-exposed cells vs. controls. Additionally, the OPE mixture altered the expression of phagocytic receptors linked to the recognition of phosphatidylserine and pathogen-associated molecular patterns. DISCUSSION The results of this in vitro study suggested that exposure to an environmentally relevant mixture of OPEs resulted in higher lipid retention in macrophages and poor efferocytic response. These effects could translate to enhanced foam cell generation resulting in higher cardiovascular mortality. Furthermore, bacterial phagocytosis was lower in OPE-exposed macrophages in an in vitro setting, which may indicate the potential for reduced bacterial clearance in models of infections. Taken together, our data provide strong evidence that mixtures of OPEs can influence the biology of macrophages and offer new mechanistic insights into the impact of OPE mixtures on the immune system. https://doi.org/10.1289/EHP13869.

中文翻译：

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体外暴露于环境相关有机磷酸酯混合物的巨噬细胞的表型和功能结果。


背景技术有机磷酸酯(OPE)是消费品中使用的阻燃剂和增塑剂。 OPE 存在于整个环境中，在室内灰尘中浓度很高。暴露于个体 OPE 与免疫功能障碍有关，尤其是巨噬细胞的免疫功能障碍。然而，OPE 以复杂混合物的形式存在，环境相关混合物对免疫系统的影响尚未得到研究。目的 本研究的目的是评估与环境相关的 OPE 混合物的毒性，该混合物使用体外表型和功能评估模拟加拿大室内灰尘对巨噬细胞的影响。方法 对用 OPE 混合物处理的 THP-1 巨噬细胞中的毒性表型生物标志物进行高内涵活细胞荧光成像。我们使用共聚焦显微镜和胆固醇分析来验证和扩展观察到的 OPE 诱导的脂质表型。然后，我们使用流式细胞术和活细胞成像进行功能测试并揭示 OPE 诱导的吞噬细胞抑制机制。最后，我们在人原代外周血单核细胞 (hPBMC) 衍生的巨噬细胞中验证了 THP-1 的发现。结果暴露于 OPE 混合物的非细胞毒性稀释液会导致更高的氧化应激，并破坏 THP-1 和原代巨噬细胞中的溶酶体和脂质稳态。我们进一步观察到，与对照组相比，OPE 暴露细胞中 THP-1 和原代巨噬细胞对凋亡细胞的吞噬作用较低。在 THP-1 巨噬细胞中，与对照组相比，OPE 暴露细胞对革兰氏阳性和革兰氏阴性细菌的吞噬作用也较低。 此外，OPE 混合物改变了与磷脂酰丝氨酸识别和病原体相关分子模式相关的吞噬细胞受体的表达。讨论 这项体外研究的结果表明，暴露于环境相关的 OPE 混合物会导致巨噬细胞中脂质滞留较高，且细胞反应较差。这些效应可能会导致泡沫细胞生成增强，导致心血管死亡率更高。此外，在体外环境中，暴露于 OPE 的巨噬细胞的细菌吞噬作用较低，这可能表明感染模型中细菌清除率可能降低。总而言之，我们的数据提供了强有力的证据，证明 OPE 混合物可以影响巨噬细胞的生物学，并为 OPE 混合物对免疫系统的影响提供新的机制见解。 https://doi.org/10.1289/EHP13869。