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Fig. 12 | Journal of Neuroinflammation

Fig. 12

From: The primary macrophage chemokine, CCL2, is not necessary after a peripheral nerve injury for macrophage recruitment and activation or for conditioning lesion enhanced peripheral regeneration

Fig. 12

Resident macrophages and alternative signaling mechanisms compensate for the loss of CCR2. A–D Representative images of CCR2gfp het and CCR2gfp KO DRGs contralateral (A, B) and ipsilateral (C, D) to a sciatic nerve transection. All macrophages are marked by CD68 immunostaining and monocyte derived macrophages are marked by GFP immunostaining. Injured DRGs in both genotypes show an increase in CD68 macrophages compared to the contralateral control (C, D vs. A, B). The CCR2gfp het DRGs have more GFP+ cells and show a small increase after injury (C). Dotted tracings indicate the cell body area and are representative of the area quantified. Dotted squares indicate the location of the insets and are 200 by 200 µm. Scale bar is 100 µm. E–H Representative images of CCR2gfp het and CCR2gfp KO DNs contralateral (E, F) and ipsilateral (G, H) to a sciatic nerve transection. All macrophages are marked by CD68 immunostaining and recruited macrophages are marked by GFP immunostaining. Injured DNs in both genotypes show an increase in CD68 macrophages compared to their contralateral control (G, H vs. E, F) but macrophages are significantly reduced in CCR2gfp KO DNs (G vs. H). The CCR2gfp het DNs have more GFP+ cells and show a substantial increase after injury (G), while the CCR2gfp KO DNs have a relative increase in resident CD68 only macrophages as well as a smaller increase in the double positive recruited macrophages (H). Scale bar is 100 µm. I–L Quantification of CD68 macrophages in the DRG cell body area (I, J) or the DN (K, L) by the percent area positively stained (I, K) and by cell counts (J, L). M, N Quantification of the percentage of recruited macrophages in the DRG cell body area (M) and in the DN (N). Percentages were calculated as the number of double positive cells over the CD68 positive cells. # Indicates a significant (p < 0.05) difference between Sh and Ax within a genotype and * indicates a significant difference between indicated genotypes within an injury condition (*p < 0.05, **p < 0.01, ***p < 0.001). All data are the mean ± SEM and n = 6 per injury condition per genotype

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