Additional file 9: Figure S8. of Analysis of monocyte infiltration in MPTP mice reveals that microglial CX3CR1 protects against neurotoxic over-induction of monocyte-attracting CCL2 by astrocytes

Quantitative analysis of presence of CCR2+ monocytes and induction of CCL2 within the striatum of MPTP mice. (A) Full timecourse analysis of the presence of CCR2-GFP+ cells (inset left; GFP, brown) within the striatum of MPTP treated CCR2-GFP mice (from 12 h to 7 days after MPTP intoxication). CCR2-GFP+ cells (inset right) were double-positive for GFP (green) and cd11b (red), identifying them as monocytes. While there was a trend for an increase at 36 h after MPTP intoxication, this did not reach statistical significance (n.s.; P > 0.05; Kruskal-Wallis test). Of note, in contrast to the striatum, in the substantia nigra, an increased CCR2+ monocyte infiltration was measured at 36 h after intoxication (see, Fig. 4d). Counts represent average CCR2-GFP+ cells within a striatal section (means +/− SEM; 5–10 section counted; n = 4 mice per condition). (Scale bar; A, 10 μm). (B) Analysis of striatal CCR2+ monocyte infiltration in MPTP mice with transgenic over-induction of astrocytic CCL2. A significant increase in striatal CCR2+ monocyte infiltration was measured (at 24 h after MPTP intoxication) in CCR2-GFP/GFAP-CCL2 mice as compared to CCR2-GFP littermates (n = 4 mice per condition; *P < 0.05; t test). Of note, this was comparable to the significant increased CCR2+ monocyte infiltration that was detectable (at 24 h after intoxication) in the substantia nigra of CCR2-GFP/GFAP-CCL2 mice (see, Fig. 6c). (C) Analysis of striatal astrocytic CCL2 induction in MPTP mice with deletion for CX3CR1. A significant increased numbers of astrocytes inducing CCL2 was measured (at 24 h after intoxication) in CX3CR1−/− mice as compared to wild-type CX3CR1+/+ littermates (n = 4 mice per condition; *P < 0.05; t test). Of note, this was comparable to the significant increased numbers of astrocytes inducing CCL2 that was detectable in the substantia nigra of CX3CR1-deleted mice (see, Fig. 7e). (PDF 682 kb)