Acute systemic immune challenge induces cognitive impairments and anhedonia through interferon-induced transmembrane protein 3 in adult male mice

Systemic immune challenge can also cause neuropsychiatric abnormalities. Interferon-induced transmembrane protein 3 (IFITM3) plays a crucial role in cellular immune defense. Previously, we have demonstrated that IFITM3 affects neurodevelopment during the early developmental stage in mice, acting through innate immune activation. However, the pathophysiological significance of IFITM3 in immune system activation in adulthood remains unclear. To address this issue, we aimed to analyze the expression level of IFITM3 in the brain and the behavioral abnormalities in polyriboinosinic-polyribocytidylic acid (polyI:C)-treated adult male C57/BL6J wild-type (WT) and Ifitm3^-/- mice. The expression levels of Ifitm3 mRNA and protein were significantly upregulated in the medial prefrontal cortex (mPFC), striatum, and hippocampus 24 h after polyI:C treatment in WT mice compared to saline-treated control mice. Furthermore, behavioral experiments revealed that polyI:C treatment induced cognitive dysfunction and anhedonia in WT mice, whereas Ifitm3^-/- mice were resistant to these disorders. In conclusion, our results demonstrated that in adult mice, immune activation following polyI:C treatment may induce cognitive dysfunction and anhedonia through IFITM3 upregulation in the brain. These results suggest that IFITM3 is an attractive therapeutic target for neuropsychiatric dysfunction following immune activation in adulthood.