LPS-induced CCL2 expression and macrophage influx into the murine central nervous system is polyamine-dependent

► Ornithine decarboxylase (ODC) is the rate-limiting step in polyamine synthesis. ► LPS challenge promotes ODC expression by CNS neurons, glia & perivascular cells. ► Inhibiting ODC decreases CNS CCL2 expression and influx of pro-inflammatory macrophages. ► Injection of polyamines into the brain is sufficient to trigger macrophage infllux.► Thus CNS cells regulate immune cell responses to pathogenic insults via polyamines.