Food-grade TiO2/TDCPP Co-exposure disrupts ACOD1/itaconate axis and is associated with TET2-NF-κB inflammation in microglia exacerbating neurotoxicity.

Food-grade titanium dioxide (TiO2) and tris (1, 3-dichloro-2-propyl) phosphate (TDCPP) are environmental pollutants with high exposure among children, which pose potential risks to neurodevelopment. However, the neurotoxicity of their co-exposure remains poorly understood. In this study, we employed C8-D1A astrocytes, BV2 microglia, and Neuro-2a neuroblastoma cells to investigate the neurotoxicity of food-grade TiO2 and TDCPP co-exposure. Toxicity experiments revealed that combined exposure to food-grade TiO2 and TDCPP elicited the most pronounced toxic effects on BV2 cells. Further co-culture experiments confirmed that this co-exposure primarily exacerbated apoptosis in Neuro-2a neurons indirectly through the activation of BV2 cells. Transcriptomic and RT-qPCR analysis revealed downregulated the expression of the aconitate decarboxylase 1 (Acod1) gene, while upregulating pro-inflammatory cytokines (Il-6, Il-1β and Tnf-α) and the DNA demethylase Tet2 in BV2 cells. Validation via Acod1 gene knockdown, exogenous itaconate intervention and co-culture experiments confirmed that co-exposure to food-grade TiO2 and TDCPP suppressed the Acod1/itaconate axis and was associated with elevated TET2 activity and NF-κB activation. These changes correlated with microglial inflammatory responses and neuronal apoptosis, suggesting potential epigenetic involvement. Our results elucidate a novel mechanism for food-grade TiO2 and TDCPP combined neurotoxicity and suggest the therapeutic potential of itaconate in mitigating neuroinflammation.