VEGFR-3 deficiency in astrocytes exacerbates the Japanese encephalitis virus infection-induced neuroinflammatory response in the brains of mice

Japanese encephalitis virus (JEV) is a neurotropic pathogen with high sensitivity and extensive replication in neurons, which leads to widespread neural damage and inflammation within the central nervous system (CNS), thereby contributing to high disability and mortality rates. Vascular endothelial growth factor receptor 3 (VEGFR-3), a receptor tyrosine kinase encoded by the FLT4 gene, plays an essential role in regulating the vascular system, especially in the development and maintenance of the lymphatic system. Although VEGFR-3 expressed in macrophages has been shown to suppress bacterial sepsis and neuroinflammation, its function in astrocytes during JEV infection remains unclear. To investigate this, we generated VEGFR-3 conditional knockout (deletion of the ligand binding domain in astrocytes) mice. VEGFR-3 deficiency in astrocytes led to the upregulated transcription of inflammatory genes and the increased viral load in the brains of JEV-infected mice, ultimately reducing their survival rate. We also observed elevated expression of inflammatory cytokines and chemokines in the brains of JEV-infected mice with VEGFR-3 deficiency in astrocytes. In vitro experiments further demonstrated that chemical inhibition of VEGFR-3 intracellular kinase activity enhanced the expression of inflammatory cytokine genes in a JEV-infected astrocyte cell line. Collectively, our results demonstrate that VEGFR-3 negatively regulates astrocyte-mediated neuroinflammation during JEV infection.