VEGF Therapy Shifts Macrophage Phenotype and Improves Renal Recovery in Chronic Kidney Disease

Abstract

Chronic kidney disease (CKD) is universally associated with renal microvascular (MV) rarefaction and inflammation. We previously developed a fusion of rh‐vascular endothelial growth factor (VEGF) conjugated to an elastin like polypeptide (ELP) vector. We showed that ELP‐VEGF therapy is renoprotective in a model of unilateral renovascular disease (RVD). Here we test the hypothesis that ELP‐VEGF therapy in a novel model of CKD will recover renal function and MV rarefaction driven partly by modulation of renal macrophages to a pro‐angiogenic phenotype.CKD was induced in 10 pigs by bilateral RVD combined with diet‐induced hypercholesterolemia. After 6 weeks, pigs received a single intrarenal dose of ELP‐VEGF or placebo and were observed for 8 weeks. Renal blood flow (RBF) and glomerular filtration rate (GFR) were quantified using multidetector computed tomography before, and 4 and 8 weeks after ELP‐VEGF therapy. Blood and urine were collected to quantify serum creatinine and albuminuria. Pigs were then euthanized and renal MV density, VEGF expression, and inflammation were quantified. Renal macrophage infiltration and phenotype was determined by concurrent staining for CD68, indoleamine 2,3 dioxygenase (IDO), and mannose receptor c type 1 (MRC1) (indicating total, M1, and M2 macrophages respectively). Further staining was performed to colocalize MRC1 and VEGF. An additional 5 pigs served as normal controls.RBF and GFR were reduced in all pigs at 6 weeks. ELP‐VEGF therapy induced a progressive recovery of RBF and GFR, accompanied by improved MV density, VEGF expression, and reduced albuminuria (1.8 ± 0.3 mg/dL vs. 2.9 ± 0.9 mg/dL in untreated CKD, p < 0.05) and creatinine (160 ± 10 μmol/L vs. 202 ± 16 μmol/L in untreated CKD, p < 0.05). Heavy IDO+/MRC1− pro‐inflammatory M1 macrophage infiltration was observed in untreated CKD and was shifted to a IDO−/MRC1+ anti‐inflammatory M2 phenotype after ELP‐VEGF therapy. Furthermore, augmented co‐expression of VEGF was observed in the MRC1+ renal macrophages (Figure).The progressive recovery of renal function far outlasted the life of administered ELP‐VEGF, suggesting that this single dose activates an endogenous mechanism of renal repair to sustain long term improvement. Accumulation of VEGF expressing M2 macrophages in the renal parenchyma may account for the recovery of MV rarefaction and renal hemodynamics after ELP‐VEGF treatment in CKD. These results suggest that modulation of macrophages towards a highly angiogenic M2 phenotype may constitute a prominent mechanism of renal recovery after ELP‐VEGF therapy in CKD.Support or Funding InformationSupport: HL95638, HL51971, GM104357, HL121527 (NIH), and EIA18490005 and IPA34170267 (AHA).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.