Fig. 1
PD-1 knockout and IFN-γ blockade aggravate muscle damage and impair muscle regeneration. WTSham: wild-type uninjured group, PSham: PD-1−/− uninjured group, WTNS: wild-type injured group with normal saline injection, WTAnti-IFN-γ: wild-type injured group with anti-IFN-γ antibody injection, PNS: PD-1−/− injured group with normal saline injection, PAnti-IFN-γ: PD-1−/− injured group with anti-IFN-γ antibody injection. A Injection sites for CTX. B PD-1 mRNA expression in wild-type mice after skeletal muscle injury. C IFN-γ mRNA expression in wild-type mice and PD-1−/− mice after skeletal muscle injury. (***P < 0.001, different from WT mice at the same timepoint, different from each other and the PD-1−/− sham mice. ###P < 0.001, different from WT sham and WT 14-day groups). D hematoxylin and eosin (HE) staining of uninjured tibialis anterior (TA) muscle of mice of both genotypes. E HE staining of injured TA muscle of mice of both genotypes injected with CTX along with either anti-IFN-γ antibody or normal saline at 3-days post injury. F HE staining of injured TA muscle of mice of both genotypes injected with CTX, along with either anti-IFN-γ antibody or normal saline at 14 days post injury. G Quantification of area with inflammatory infiltration as in E. H Quantification of regenerated muscle fiber diameter as in F, I myogenin mRNA expression at 3 days post injury, J myogenin mRNA expression at 14 days post injury. *P < 0.05, **P < 0.01, ***P < 0.001, different from NS treatment when comparing the same genotype. #P < 0.05, ##P < 0.01, ###P < 0.001, different from WT mice when comparing the same treatment. Data are shown as mean ± standard deviation (SD), n = 6 (B, C, I, J), n = 3 (G, H). Black scale bar, 200 μm; green scale bar, 50 μm; blue scale bar, 20 μm