Pernicious effects of plastic particles, emergent contaminants worldwide, have been described in different species. In teleost species, alterations of immune function after exposure to nanoplastics (NPs) have been reported, but the interaction with cortisol – hypothalamic–pituitary–adrenal (HPI) axis has not yet been explored. Furthermore, the role of dissolved organic matter on the effects of NPs is poorly known. Thus, the aims of this research were to assess if polystyrene NPs (PSNPs) acted as a stressor on juvenile European seabass (Dicentrarchus labrax), interfering with the immune response, as well as to elucidate if humic acids (HA) modulated the potential effects of PSNPs. A short-term exposure to PSNPs and HA elicited an immuno-modulatory response, with an activation of steroidogenic stress-related pathways. An upregulation of anti-inflammatory cytokine (il10, tgfb) and stress-related (mc2r, gr1) transcripts were observed after exposure to HA and PSNPs both individually and in co-exposure. No notable alteration of inflammatory markers was consistently found, which may reflect a protective anti-inflammatory effect of HA in the presence of PSNPs. Nevertheless, there seems to be a more complex interaction between both components. Overall, data show that understanding the interaction of NPs with dissolved organic substances is key to deciphering their environmental risks.

在不同物种中已经描述了塑料微粒的有害影响，这种污染物是全球范围内的新兴污染物。在硬骨鱼类中，已经报道了暴露于纳米塑料（NPs）后免疫功能的改变，但是尚未研究与皮质醇-下丘脑-垂体-肾上腺（HPI）轴的相互作用。此外，人们还不清楚溶解有机物对NP的作用。因此，本研究的目的是评估聚苯乙烯NPs（PSNPs）是否对欧洲鲈鱼（Dicentrarchus labrax），干扰免疫反应，并阐明腐殖酸（HA）是否调节了PSNP的潜在作用。短期暴露于PSNPs和HA会引发免疫调节反应，并激活类固醇生成应激相关途径。分别暴露于HA和PSNPs和共同暴露后，观察到抗炎细胞因子（il10，tgfb）和应激相关（mc2r，gr1）转录本的上调。始终没有发现炎性标志物的显着变化，这可能反映了PSNP存在时HA的保护性抗炎作用。但是，这两个组件之间似乎存在更复杂的交互。总体而言，数据表明，了解NP与溶解的有机物质的相互作用是破解其环境风险的关键。