Figure 3.

Astrocytic calcineurin protects against inflammatory damage after brain trauma. A, In AIC mice expressing ΔCnA (not treated with Dox), the number of dying neurons (β3-tubulin⁺-activated caspase 3⁺ cells) 5 d after the lesion in the area surrounding a traumatic injury (asterisk) of the parietal cortex was reduced compared with AIC mice treated with Dox for 1 week before lesion. Scale bar, 50 μm. B, Expression of ΔCnA in AIC mice (−Dox) reduced the number of reactive astrocytes (GFAP⁺; green) expressing Cox2 (red) in the lesioned area (asterisk). Note expression of Cox2 also by unidentified GFAP⁻ cells surrounding the lesion site. Scale bar, 100 μm. C, Levels of both Cox2 and iNOS2 at the injury site were also dramatically reduced in ΔCnA-expressing AIC mice (p < 0.001 vs AIC +Dox, for both markers; n = 10 at 5 d after lesion). Control, Sham operated; Inj, brain injury. D, Levels of MHCII (a marker of microglia activation) were increased at the lesion site 5 d after brain trauma in AIC mice not expressing ΔCnA (+Dox; n = 10), but the increase was smaller when expressing ΔCnA (−Dox; n = 10). Protein load in gels was normalized by measuring β-actin levels. Bottom histograms, Number of MHCII⁺, CD11b⁺ (a marker of infiltrating macrophages), and double MHCII⁺–CD11b⁺ cells at the lesioned site in AIC mice treated with Dox 1 week before lesion (+Dox), not treated with Dox (−Dox), or treated with Dox until 2 d after the lesion (±Dox). In the absence of Dox, when ΔCnA is expressed in astrocytes, the number of MHCII⁺ and MHCII⁺–CD11b⁺ cells is significantly reduced, whereas CD11b⁺ cells remain unaffected. Note that the reduction is also present when AIC mice started to express ΔCnA 2 d after the lesion was produced (***p < 0.001 vs −Dox and ±Dox; n = 5 per group). Photomicrographs, Representative MHCII⁺ and CDb11⁺ cells located in the vicinity of the lesion site (asterisk). Cell counts were done in double-stained brain sections. Scale bar, 50 μm.