Food preservative tBHQ modulates Th17/Treg balance through AHR/NRF2 xenosensors and increases the sensitivity of T cells to activation stimuli.

In this study, we investigated the effect of the food preservative tert-butylhydroquinone (tBHQ) on the activation of murine CD4+ T cells. We assessed the role of the nuclear factor erythroid 2-related factor 2 (NRF2) and the aryl hydrocarbon receptor (AHR) and conducted protein interaction studies to identify potential molecular targets of tBHQ. BALB/c mice received tBHQ orally (1.5% [w/w]), after which splenic T cells (Th1, Th2, Th17, Treg) were analyzed for number and activation sensitivity. While the number of effector T cells remained unchanged, their response to stimulation was accelerated in tBHQ treated animals. In contrast, Treg cells increased in number after treatment with this food additive but displayed reduction in count upon activation. In vitro experiments showed that tBHQ modulates the differentiation of Th17 and Treg cells. Pretreating these cells with NRF2 inhibitor trigonelline and/or AHR inhibitor TMF (6, 2, 4'-trimetoxi-flavone) altered the effect of tBHQ on these cells. We found 14 candidate targets of this chemical (AHR, KEAP1, NQO1, RORC, TBX21, IL6, GATA3, BCL2, FOXP3, IFNG, JAK2, ALB, TGFBR1, and HSP90AA1). Network analysis revealed coordinated regulation of pathways associated with inflammation, T cell differentiation, and xenobiotic response. In conclusion, our studies highlight the importance of the T cell response after tBHQ exposure and suggest multiple proteins and pathways that are relevant to the immunotoxicity of this compound.