Maternal Immune Activation and Neuropsychiatric Disorders: The Intricate Puzzle of Autism Spectrum Disorder

Pregnancy is a complex phenomenon in which several physiological changes are orchestrated to provide appropriate fetal development. In this context, the immune system plays important roles, oscillating between many states in the spectrum of tolerance and inflammation in order to balance the maternal–fetal interface. Infections caused by different agents are capable to trigger countless alterations in immune profile, which are especially harmful during the gestational period, being already linked to important development impairments. Regarding this, numerous evidence have pointed out the relation between maternal immune activation (MIA) and neurodevelopmental disorders like schizophrenia and autism spectrum disorder (ASD). Specifically, ASD is a highly prevalent disorder that stands out as a field of study because of its extensive complexity and relatively poorly known etiological mechanisms. Several animal models of MIA already helped to understand possible pathways by which immune activation could increase ASD risk, clarifying important roles of immune-related factors in the modulation of fetal development. Therefore, the main objective of this chapter is to compile and comment evidence that may improve the knowledge between immune system and ASD in the context of MIA.