CCR2 deficiency impairs macrophage infiltration and improves cognitive function after traumatic brain injury - PubMed (original) (raw)
Early macrophage infiltration is markedly reduced in Ccr2−/− mice after traumatic brain injury (TBI). (A) Representative flow cytometry plots of brain cell preparations isolated from contralateral and ipsilateral brain hemispheres 4 d after TBI. Gated cells represent the proportion of CD45hi CD11b+cells identified as macrophages in the brain cell preparation. Ly6G+CD45hiCD11b+granulocyte cells were excluded from these plots (_n_=6–8 animals per group). (B) Absolute number of brain macrophages following TBI in contralateral and ipsilateral hemispheres in wild-type and Ccr2−/− mice sacrificed at 1, 4, 7, and 14 d after surgery (mean±standard error of the mean) was assessed. Two-way ANOVA for main effects of genotype and TBI was conducted at each time point. The main effect of genotype was significant at days 1 and 4, F(1,20)=13.9, **_p_=0.001, and F(1,18)=15.1,**_p_=0.001, respectively. The effect of TBI on mean macrophage number was also significant at days 1 and 4, F(1,20)=16.4, _p_=0.0006, and F(1,18)=33.4, p<0.0001. A significant interaction effect was found on days 1 and 4, F(1,20)=12.4, _p_=0.002, and F(1,19)=15.5, _p_=0.001), indicating the effect of injury on mean macrophage number was greater among wild-type mice than among Ccr2−/− mice. However, on days 7 and 14, there were neither significant interaction effects nor main effects of genotype, although there were significant main effects of TBI, F(1,9)=12.6, _p_=0.006, and F(1,14)=5.16, _p_=0.039, for day 7 and day 14, respectively). Group sizes for wild-type TBI groups in B and C are as follows: day 1, _n_=14; day 4, _n_=8; day 7, _n_=4; and day 14, _n_=8). Group sizes for Ccr2−/− TBI mice are: day 1, _n_=5; day 4, _n_=6; day 7, _n_=5; day 14, _n_=6. Sham group sizes for all time points are 2 to 4. (C) Absolute number of neutrophils in the brain following TBI in contralateral and ipsilateral hemispheres was assessed. Although significant effects of TBI were found on days 1 and 4, F(1,18)=10.8, _p_=0.004, and F(1,18)=13.9, _p_=0.002, respectively, there were no significant effects of interaction or genotype at any time point. Color image is available online at