Kidney-resident macrophages promote a proangiogenic environment in the normal and chronically ischemic mouse kidney

Renal artery stenosis (RAS) caused by narrowing of arteries is characterized by microvascular damage. Macrophages are implicated in repair and injury, but the specific populations responsible for these divergent roles have not been identified. Here, we characterized murine kidney F4/80+CD64+ macrophages in three transcriptionally unique populations. Using fate-mapping and parabiosis studies, we demonstrate that CD11b/cint are long-lived kidney-resident (KRM) while CD11chiMf, CD11cloMf are monocyte-derived macrophages. In a murine model of RAS, KRM self-renewed, while CD11chiMf and CD11cloMf increased significantly, which was associated with loss of peritubular capillaries. Replacing the native KRM with monocyte-derived KRM using bone marrow transplantation followed by RAS, amplified loss of peritubular capillaries. To further elucidate the nature of interactions between KRM and peritubular endothelial cells, we performed RNA-sequencing on flow-sorted macrophages from Sham and RAS kidneys. KRM showed a prominent activation pattern in RAS with significant enrichment in reparative pathways, like angiogenesis and wound healing. In culture, KRM increased proliferation of renal peritubular endothelial cells implying direct pro-angiogenic properties. Human homologs of KRM identified as CD11bintCD11cintCD68+ increased in post-stenotic kidney biopsies from RAS patients compared to healthy human kidneys, and inversely correlated to kidney function. Thus, KRM may play protective roles in stenotic kidney injury through expansion and upregulation of pro-angiogenic pathways Overall design: CD11chiMf Sham, n=3; CD11chiMf RAS, n=4; CD11cloMf Sham, n=3; CD11cloMf RAS, n=4; KRM Sham, n=4; KRM RAS, n=3;

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Puranik AS, Leaf IA, Jensen MA, Hedayat AF, Saad A, Kim KW, Saadalla AM, Woollard JR, Kashyap S, Textor SC, Grande JP, Lerman A, Simari RD, Randolph GJ, Duffield JS, Lerman LO