Clinical Perspectives on Maternal Immune Activation Theory

Neurodevelopmental disordersNeurodevelopmental disorder (NDD), including autism spectrum disorderAutism spectrum disorder (ASD), have increased worldwide. ASD is a heterogeneous disorder, showing the core symptoms are social and communication problems, and repetitive behavior. ASD has a complicated etiology consisting of genetic and environmentalEnvironmental risk factors. Over the past three decades, the maternal immune activationMaternal immune activation (MIA) theory has emerged as establishing evidence that prenatal exposure to various environmentalEnvironmental factors can develop NDD, such as ASD. Maternal IL-17A elevation or aberrant microgliaMicroglia of offspring are critical factors in MIA pathogenesis. Thus, various factors, including air pollutantsPollutant and maternal hypertension, are currently considered relevant risk factors for MIA, although it has been based initially on maternal viral or bacterial infection. Epigenome-wide association studies also clarify the role of prenatal environmentalEnvironmental exposures on ASD. The current chapter provides an overview of the MIA theory, focusing on the connection of the findings of animal experiments to clinical findings. It also describes the current issues and the future perspectives to translate them into clinical settings.