Aflatoxin B₁ Exposure Aggravates Neurobehavioral Deficits and Immune Dysfunctions of Th1, Th9, Th17, Th22, and T Regulatory Cell-Related Transcription Factor Signaling in the BTBR T⁺Itpr3^tf/J Mouse Model of Autism

Autism spectrum disorder (ASD) is a neurodevelopmental disease characterized by impaired communication, reciprocal social interactions, restricted sociability deficits, and stereotyped behavioral patterns. Environmental factors and genetic susceptibility have been implicated in an increased risk of ASD. Aflatoxin B-1 (AFB(1)) is a typical contaminant of food and feed that causes severe immune dysfunction in humans and animals. Nevertheless, the impact of ASD on behavioral and immunological responses has not been thoroughly examined. To investigate this phenomenon, we subjected BTBR T(+)Itpr3(tf)/J (BTBR) mice to AFB(1) and evaluated their marble-burying and self-grooming behaviors and their sociability. The exposure to AFB(1) resulted in a notable escalation in marble-burying and self-grooming activities while concurrently leading to a decline in social contacts. In addition, we investigated the potential molecular mechanisms that underlie the impact of AFB(1) on the production of Th1 (IFN-gamma, STAT1, and T-bet), Th9 (IL-9 and IRF4), Th17 (IL-17A, IL-21, ROR gamma T, and STAT3), Th22 (IL-22, AhR, and TNF-alpha), and T regulatory (Treg) (IL-10, TGF-beta 1, and FoxP3) cells in the spleen. This was achieved using RT-PCR and Western blot analyses to assess mRNA and protein expression in brain tissue. The exposure to AFB(1) resulted in a significant upregulation of various immune-related factors, including IFN-gamma, STAT1, T-bet, IL-9, IRF4, IL-17A, IL-21, ROR gamma, STAT3, IL-22, AhR, and TNF-alpha in BTBR mice. Conversely, the production of IL-10, TGF-beta 1, and FoxP3 by CD4(+) T cells was observed to be downregulated. Exposure to AFB1 demonstrated a notable rise in Th1/Th9/Th22/Th17 levels and a decrease in mRNA and protein expression of Treg. The results above underscore the significance of AFB(1) exposure in intensifying neurobehavioral and immunological abnormalities in BTBR mice, hence indicating the necessity for a more comprehensive investigation into the contribution of AFB(1) to the development of ASD.