Supplementing with Vitamin D during Pregnancy Reduces Inflammation and Prevents Autism-Related Behaviors in Offspring Caused by Maternal Immune Activation.

Autism spectrum disorder (ASD), a neurodevelopmental disorder of unknown etiology with limited treatment options, has emerged as a significant public health concern. Studies have demonstrated that prenatal vitamin D deficiency is a risk factor for ASD development in offspring; however, the underlying mechanism remains unclear. In this project, vitamin D was administered orally to pregnant mice with/without the subsequent administration of polyriboinosinic polyribocytidylic acid (Poly(I:C)), which induced the maternal immune activation (MIA). Our results showed that vitamin D supplementation during pregnancy alleviated MIA-induced ASD-like behaviors in offspring. Moreover, vitamin D supplementation reduced the MIA-induced elevation of interleukin-6 (IL-6) and IL-17a levels in both the maternal ileum and fetal brains. It also suppressed signal transducer and activator of transcription 3 (Stat3) activation and the elevated expression of serum amyloid A1 and A2 (SAA1/2) in the ileum of MIA-affected pregnant mice. This study revealed that vitamin D may reduce the expression of IL-17a by inhibiting the IL-6/Stat3/SAA signaling pathway, thereby improving ASD-like behavior in offspring mice, and provide a new theoretical support for the prevention and treatment of ASD by scientific dietary interventions and nutritional supplement during pregnancy.