Fig. 4

Gene profiling predicts exaggerated activation and recruitment of monocytes in aged TBI. Gene array data were uploaded into IPA software, genes with a fold change (relative to young sham) ≥1.5 or ≤−1.5 were included for disease and biological function analysis. a Upregulated functions across all three groups were sorted by activation z-score of the aged TBI group, only the top ten functions are presented with the black arrow emphasizing the activation of monocytes. b Functional network diagram of predicted and measured regulators is presented for both young TBI and aged TBI, which highlight an overrepresented activation for this function for aged TBI group. c Using Dbl-Het reporter mice (n = 6/group), macrophages (CD11b⁺F4/80⁺) were delineated based upon their relative expression of GFP (CX3CR1) from RFP (CCR2) by flow cytometry. There were relatively very few CCR2⁺ macrophages (blue box) in the sham animals; however, there was a significant increase in this subpopulation due to age. However, 24 h following TBI, there was a significant increase in the mean number of CCR2⁺ macrophages (blue box) in the aged animals compared to young. Data were analyzed using Student’s t test and are represented by the mean + SEM. **p < 0.01