Di(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer and environmental contaminant. DEHP exposure has been linked to neurotoxicity in Alzheimer's disease (AD), yet the underlying mechanisms remain unclear. Here we found that DEHP exacerbated amyloid-beta (Aβ)-induced toxicity in transgenic AD Caenorhabditis elegans (C. elegans) models. Meanwhile the accumulation of SQST-1 was increased, indicating that the autophagic flux was impaired. Consistently, Aβ deposition was elevated in DEHP-treated AD C. elegans. Further investigation revealed that DEHP treatment resulted in lysosomal dysfunction accompanied by a significant decrease in lysosome number. The expression of hlh-30, a key transcription factor involved in lysosomal biogenesis, as well as its downstream lysosome-related genes, including cup-5, vha-17, and lmp-1, was reduced by DEHP. Moreover, hlh-30 RNAi abolished the exacerbation of Aβ toxicity by DEHP, indicating that the modulation of hlh-30 was a critical mechanism underlying the effects of DEHP. Additionally, DEHP aggravated oxidative stress in AD C. elegans, while the antioxidant N-acetylcysteine alleviated lysosomal impairment and reduced Aβ deposition, suggesting that the elevated oxidative stress was a key contributor to DEHP-induced lysosomal dysfunction and autophagy impairment. These findings highlight lysosomal impairment as a key mechanism contributing to DEHP-exacerbated toxicity in AD models, and suggest the possibility of using antioxidants to prevent DEHP-induced toxicity.
