NOS2 and Brain atrophy: The immunomodulator not only downregulated the expression of pro-inflammatory markers (IL-1β, iNOS, CD86) and upregulated anti-inflammatory markers (IL-10, Arg-1, CD206) both in in vitro cellular model and in vivo stroke model to improve the local immune milieu, but it also reduced brain atrophy volume in stroke mice, enhanced neurological behavioral functions, and precisely coordinated immune cells with the neurovascular unit to facilitate both angiogenesis and neurogenesis.