ASS1 and autoimmune myocarditis: Using the experimental autoimmune myocarditis (EAM) model, Hua et al. 128 demonstrated that the major macrophage population present during the acute phase—distinguished by differential expression of Nos2, Arg1, and Ass1—produces nitric oxide through Ass1-mediated biosynthesis, thereby enhancing phagosomal antigen processing, IFN-γ responsiveness, and ROS metabolism.