Kidney residency of VISTA-positive macrophages accelerates repair from ischemic injury.

Tissue-resident macrophages have unique tissue-specific functions in maintaining homeostasis and resolving inflammation. However, the repair role and relevant molecules of kidney-resident macrophages after ischemic injury remain unresolved. To this end, mice without kidney-resident R1 macrophages but containing infiltrating monocyte-derived R2 macrophages were generated using differential cellular kinetics following clodronate liposome treatment. When ischemia-reperfusion injury was induced in these mice, late phase repair was reduced. Transcriptomic and flow cytometric analyses identified that V-domain Ig suppressor of T cell activation (VISTA), an inhibitory immune checkpoint molecule, was constitutively expressed in kidney-resident R1 macrophages, but not in other tissue-resident macrophages. Here, VISTA functioned as a scavenger of apoptotic cells and served as a checkpoint to control kidney-infiltrating T cells upon T cell receptor-mediated stimulation. Together these functions improved the repair process after ischemia-reperfusion injury. CD14 CD33 mononuclear phagocytes of human kidney also expressed VISTA, which has similar functions to the mouse counterpart. Thus, VISTA is upregulated in kidney macrophages in a tissue-dependent manner and plays a repair role during ischemic injury.