Figure 6: Impacts of IL-17A on muscle stem cells and repair.

(A-D) B6 mice were treated with vehicle or rIL-17A early, late or continuously (cont.) after CTX-induced injury. Muscles were analyzed 7 days post-injury. A) Treatment schematic. B) Distribution of cross-sectional areas of individual centrally nucleated fibers (left), and average fiber areas for individual mice (right). C) Quantification of muscle fibrotic areas via PSR staining. D) Quantification of muscle NFs. (E-G) RNA-seq analysis of sorted MuSCs from PBS- or rIL-17A-treated mice on days 0, 1 and 3 after CTX-induced injury. Treatment schedule as per panel A. E) Il17ra transcript quantification. F) k-means clustering of dynamically differential transcripts. Only select clusters are depicted. G) FC/FC plots for PBS- vs rIL-17A-treated mice on day 3 versus 1 after injury. MuSC differentiation signature genes⁵⁴ highlighted in red. (H-J) Freshly isolated MuSCs were cultured in vitro with or without rIL-17A. Representative images (left, 2–3 independent experiments) and summary data (right) of H) EdU incorporation, I) myogenin (MyoG), and J) Myosin Heavy Chain (MyHC) expression after 2, 3 and 4 days of culture, respectively. Kruskal-Wallis test (B left), Chi-squared test of the number of signature genes falling on either side of the diagonal (G), Unpaired t-test (H-J), otherwise one-way ANOVA. See also Figure S6.