CX3CL1 and brain injury: CX3CL1 expression is upregulated in intact neurons within the penumbra while both CX3CL1 and CX3CR1 expression are upregulated in infarcted brain in experimental stroke model in rats [14].This protein may be involved in the inflammatory response to traumatic brain injury (TBI), particularly in the accumulation of leukocytes in the injured parenchyma [19].