Fig. 6

Immunostaining, stereological quantification, and qPCR analysis of M2 and M1 polarization markers in cortex at 7 days post-TBI. a–d YM1 shows a strong increase in staining in the CX3CR1 KO-TBI compared to CX3CR1 WT-TBI at 7 days post-injury. a Micrograph at ×4 magnification showing YM1 staining in the proximity of the lesion area in CX3CR1 KO-TBI mice. b Higher magnification (×10) of the area indicated by the red arrow in (a). c Higher magnification (×20) of the area in the proximity of the lesion of CX3CR1 WT-TBI and CX3CR1 KO-TBI showing in more detail microglial YM1 morphology. d Unbiased stereology revealed a significant increase in the number of YM1 and CD2O6⁺ cells (right panel) in the cortex of CX3CR1 KO-TBI mice (n = 3) compared to CX3CR1 WT-TBI (n = 4). e–h CD206 shows a strong increase in staining in the CX3CR1 KO-TBI compared to CX3CR1 WT-TBI at 7 days post-injury. e Micrograph at ×4 magnification showing CD206 staining in the proximity of the lesion area in CX3CR1 KO-TBI mice. f Higher magnification (×10) of the area indicated by the red arrow in (a). g Higher magnification (×20) of the area in the proximity of the lesion of CX3CR1 WT-TBI and CX3CR1 KO-TBI showing in more detail microglial CD206 morphology. h Unbiased stereology revealed a significant increase in the number of CD2O6⁺ cells in the cortex of CX3CR1 KO-TBI mice compared to CX3CR1 WT-TBI. YM1 and CD206 were not detected in sham mice (**p < 0.001). i Relative mRNA levels of M2 marker TGFβ were significantly lower in sham CX3CR1 sham KO (n = 5) compared to CX3CR1 sham WT (n = 5). Following TBI, the expression of TGFβ significantly increased in CX3CR1 KO mice compared to sham (n = 5; **p < 0.001) but was not different compared to CX3CR1 WT-TBI (n = 5). M1 markers iNOS (middle panel) and IL-1β (right panel) were similar in the cortex of CX3CR1 sham KO (n = 5) compared to CX3CR1 sham WT (n = 5). Following injury, iNOS and IL-1β mRNA levels in CX3CR1 KO-TBI (n = 5) were significantly decreased compared to CX3CR1 WT-TBI (n = 5). **p < 0.001). CX3CR1 sham WT (white bar), CX3CR1 sham KO (green bar), CX3CR1 WT-TBI (red bar), and CX3CR1 KO-TBI (blue bar)