Prolyl Hydroxylase Domain Inhibitor Protects against Metabolic Disorders and Associated Kidney Disease in Obese Type 2 Diabetic Mice
Authors: Sugahara Mai , Tanaka Shinji , Tanaka Tetsuhiro , Saito Hisako , Ishimoto Yu , Wakashima Takeshi , Ueda Masatoshi , Fukui Kenji , Shimizu Akira , Inagi Reiko , Yamauchi Toshimasa , Kadowaki Takashi , Nangaku Masaomi 
Published: January 2020

Significance Statement
Prolyl hydroxylase domain (PHD) inhibitors, primarily developed to treat renal anemia, stimulate erythropoietin production through activation of hypoxia-inducible factor (HIF). Because HIF affects a broad spectrum of genes, PHD inhibitors are thought likely to have other effects, including protection against metabolic disorders. The authors show that in obese type 2 diabetic mice, administration of the PHD inhibitor enarodustat not only improves glucose and lipid metabolism, but also reduces albuminuria and ameliorates glomerular epithelial and endothelial damage. Enarodustat-treated mice also exhibit reduced glomerular expression and urinary excretion of C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1). The authors further demonstrate that enarodustat directly suppresses CCL2/MCP-1 production via HIF-1 activation in mesangial cells. These results indicate that enarodustat has renoprotective effects in addition to its potential to protect against metabolic disorders.

Background
Prolyl hydroxylase domain (PHD) inhibitors, which stimulate erythropoietin production through the activation of hypoxia-inducible factor (HIF), are novel therapeutic agents used for treating renal anemia. Several PHD inhibitors, including enarodustat, are currently undergoing phase 2 or phase 3 clinical trials. Because HIF regulates a broad spectrum of genes, PHD inhibitors are expected to have other effects in addition to erythropoiesis, such as protection against metabolic disorders. However, whether such beneficial effects would extend to metabolic disorder–related kidney disease is largely unknown.

Methods
We administered enarodustat or vehicle without enarodustat in feed to diabetic black and tan brachyury (BTBR) ob/ob mice from 4 to 22 weeks of age. To elucidate molecular changes induced by enarodustat, we performed transcriptome analysis of isolated glomeruli and in vitro experiments using murine mesangial cells.

Results
Compared with BTBR ob/ob mice that received only vehicle, BTBR ob/ob mice treated with enarodustat displayed lower body weight, reduced blood glucose levels with improved insulin sensitivity, lower total cholesterol levels, higher adiponectin levels, and less adipose tissue, as well as a tendency for lower macrophage infiltration. Enarodustat-treated mice also exhibited reduced albuminuria and amelioration of glomerular epithelial and endothelial damage. Transcriptome analysis of isolated glomeruli revealed reduced expression of C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1) in enarodustat-treated mice compared with the vehicle-only group, accompanied by reduced glomerular macrophage infiltration. In vitro experiments demonstrated that both local HIF-1 activation and restoration of adiponectin by enarodustat contributed to CCL2/MCP-1 reduction in mesangial cells.

Conclusions
These results indicate that the PHD inhibitor enarodustat has potential renoprotective effects in addition to its potential to protect against metabolic disorders.