CCL5 and brain injury: To further investigate the role of CCL5 following brain injury, we administered recombinant CCL5 (300 pg/g) intranasally into the brains of CCL5 knockout (KO) mice immediately prior to the induction of mild traumatic brain injury (mTBI) (Pretreatment CCL5, PreL5, as shown in Supplementary Fig. 3A) or recombinant CCL5 (30 pg/g) from 3 days after injury every 2 days for 28 days (post treatment CCL5, PostL5 as shown in Supplementary Fig. 3A).