ARG2 and neuromuscular disease caused by qualitative or quantitative defects of dystrophin: Because arginine metabolism by arginase-2 in M2 macrophages can drive fibrosis following tissue injury [54], [55] and arginase-2-expressing M2 macrophages are present in elevated numbers in mdx skeletal muscle and hearts, we tested whether ablation of arginase-2 in mdx mice could affect fibrosis and associated features of dystrophinopathy.