Disruption of Alternative Splicing in the Amygdala of Pigs Exposed to Maternal Immune Activation

Abstract

The inflammatory response of gestating females to infection or stress can disrupt gene expression in the offspring’s amygdala, resulting in lasting neurodevelopmental, physiological, and behavioral disorders. The effects of maternal immune activation (MIA) can be impacted by the offspring’s sex and exposure to additional stressors later in life. The objectives of this study were to investigate the disruption of alternative splicing patterns associated with MIA in the offspring’s amygdala and characterize this disruption in the context of the second stress of weaning and sex. Differential alternative splicing was tested on the RNA-seq profiles of a pig model of viral-induced MIA. Compared to controls, MIA was associated with the differential alternative splicing (FDR-adjusted p-value < 0.1) of 292 and 240 genes in weaned females and males, respectively, whereas 132 and 176 genes were differentially spliced in control nursed female and male, respectively. The majority of the differentially spliced (FDR-adjusted p-value < 0.001) genes (e.g., SHANK1, ZNF672, KCNA6) and many associated enriched pathways (e.g., Fc gamma R-mediated phagocytosis, non-alcoholic fatty liver disease, and cGMP-PKG signaling) have been reported in MIA-related disorders including autism and schizophrenia in humans. Differential alternative splicing associated with MIA was detected in the gene MAG across all sex-stress groups except for unstressed males and SLC2A11 across all groups except unstressed females. Precise understanding of the effect of MIA across second stressors and sexes necessitates the consideration of splicing isoform profiles.

Prefrontal Cortex Response to Prenatal Insult and Postnatal Opioid Exposure

“…The enrichment of immune categories (e.g., chemokine signaling, Herpes simplex infection) can be related to the enrichment of inflammatory pathways among genes differentially expressed in the prefrontal cortex of individuals with schizophrenia relative to controls [ 43 ]. The over-representation of the ribosome pathway among genes presenting an interaction effect including under-expression in morphine-treated MIA pigs in the prefrontal cortex is consistent with alternative splicing and gene profiles in the amygdala of pigs exposed to weaning stress and MIA [ 19 , 44 ]. The previous enrichment and pattern are consistent with the under-expression of genes in the ribosome pathway detected in fetal mouse brain exposed to Poly (I:C)-elicited MIA relative to control mice [ 45 ].…”

“…Furthermore, also impacted by MIA were genes in the protein kinase cGMP-dependent family, including PRKG1 , PRKG2 , and PRKCB ( Table 2 ). Enrichment of the cGMP-dependent PRKG signaling pathway was detected among differentially spliced genes in the amygdala of pigs exposed to MIA [ 44 ]. In addition, increased phosphorylation of PRKG targets was reported in the anterior cingulate cortex of SSD compared to control individuals, and PRKG molecule profiles had been linked to ASD [ 73 ].…”

Influence of Maternal Immune Activation and Stressors on the Hippocampal Metabolome

“…Maternal immune activation during gestation is associated with changes in the offspring’s neurological and molecular mechanisms underlying behavioral disorders, including autism spectrum and schizophrenia, later in life [ 27 , 28 , 29 , 31 , 37 , 38 ]. Amino acid metabolite profiles in this study were consistent with changes in amino acids and disruption of amino acid pathways associated with stress and immune function.…”

“…The joint effects of prenatal and postnatal stressors have been reasoned under the double-hit hypothesis studied in rodent, pig, and primate models [ 9 , 21 , 22 , 23 ]. The combination of weaning stress and MIA affects serum indicators [ 24 ], metabolomics [ 25 ], the amygdala and hippocampus transcriptome [ 26 , 27 , 28 , 29 , 30 ], and the behavior of pigs [ 31 ]. MIA and postnatal challenges have [ 9 , 21 , 22 , 23 ] been associated with changes in serum indicators and neurodevelopmental disorders, including schizophrenia and autism spectrum disorders in humans [ 18 , 19 ].…”

Hippocampal Changes Elicited by Metabolic and Inflammatory Stressors following Prenatal Maternal Infection

“…A study of MIA induced by the porcine reproductive and respiratory syndrome virus (PRRSV) during the final third of gestation reported elevated expression of inflammatory cytokine genes and low expression of major histocompatibility complex II genes in the fetal hippocampi five weeks post-infection [5]. Maternal immune activation continued to alter gene expression, and alternative splicing in the hippocampus and the amygdala interacted with stressors at three weeks of age [6,7]. The interaction of weaning and MIA elicited the under-expression of genes in the terpenoid backbone biosynthesis pathway in the hippocampus [8] and the neuroactive ligand-receptor pathway in the amygdala [9].…”