Figure 8. Microglia are necessary for early recovery from MN disease.
(a) Timeline for experiments using PLX3397 to deplete microglia in rNLS8 mice. (b–c) rNLS8 mice given Nutella containing PLX3397 (right), but not control (left) still clasp after 2 weeks on DOX. #, paired t-test, t=3.5, d.f.=4, p=0.02, relative to control mice at 4 weeks off DOX. ***, t=−5.8, d.f.=8, p=0.0004, relative to control mice at 4 weeks off DOX + 2 weeks on. (d) PLX3397-treated mice trend towards reduced evoked CMAP. t=2.3, d.f.=8, p=0.05. (e) PLX3397 treatment reduced the density of IBA-1+ cells in SC. ***, t=5.6, d.f.=8, p=0.0005. (f–h) hTDP-43 (green) is cleared from sham-treated rNLS8 MNs (f), whereas many hTDP-43-positive MNs remain in the PLX3397-treated lumbar SC (g). (h) Quantification of average fluorescence intensity per MN in control (grey) and PLX3397-treated mice (blue) shows that the MNs in microglia-depleted animals are more hTDP-43 immunopositive; **, t=3.3, d.f.= 8, p=0.01. (i) PLX3397-treated mice (n=4) have significantly fewer intact NMJs in their TA muscles than controls. **, t=3.5, d.f.=7, p=0.009. (j–k) Representative cryosections immunostained with CD11b (red) to label microglia and VAChT (green) to label MNs. (l) There are significantly fewer MNs in PLX3397-treated mice compared to control, ***, t=8.7, d.f.=8, p=0.00002. Scale bar= 100 µm. (m–n) Many microglia (IBA-1, red) from control (m) and PLX3397-treated (n) rNLS8 mice express CD68 (blue). Scale bar= 50 µm. Bars represent mean ± S.D., n=5 per group and t-tests unpaired and two-tailed, unless otherwise specified. See Supplementary Table 2 for data summary.