Glycolysis in Peritubular Endothelial Cells and Microvascular Rarefaction in CKD

Background: Peritubular endothelial cell dropout leading to microvascular rarefaction is a common manifestation of chronic kidney disease (CKD). The role of metabolism reprogramming in peritubular endothelial cell loss in CKD is undetermined. Methods: Single-cell sequencing and metabolic analysis were used to characterize metabolic profile of peritubular endothelial cells from CKD patients and from CKD mouse models. In vivo and in vitro models demonstrated metabolic reprogramming in peritubular endothelial cells in conditions of CKD and its contribution to microvascular rarefaction. Results: Here, we identified glycolysis as a top dysregulated metabolic pathway in peritubular endothelial cells from CKD patients. Specifically, CKD peritubular endothelial cells were hypoglycolytic while displaying an anti-angiogenic response with decreased proliferation and increased apoptosis. The hypoglycolytic phenotype of peritubular endothelial cells was recapitulated in CKD mouse models and in peritubular endothelial cells stimulated by hydrogen peroxide (H2O2). Mechanically, oxidative stress, through activating a redox sensor kruppel-like transcription factor 9, downregulated the glycolytic activator 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase (PFKFB3) expression, thereby reprogramming peritubular endothelial cells towards a hypoglycolytic phenotype. PFKFB3 overexpression in peritubular endothelial cells restored H2O2-induced reduction in glycolysis and cellular ATP levels, and enhanced the G1/S cell cycle transition, enabling peritubular endothelial cells to improve proliferation and reduce apoptosis. Consistently, restoration of peritubular endothelial cell glycolysis in CKD mice, via overexpressing endothelial Pfkfb3, reversed the anti-angiogenic response in peritubular endothelial cells and protected the kidney from microvascular rarefaction and fibrosis. In contrast, suppression of glycolysis by endothelial Pfkfb3 deletion exacerbated microvascular rarefaction and fibrosis in CKD mice. Conclusions: Our study revealed a disrupted regulation of glycolysis in peritubular endothelial cells as an initiator of microvascular rarefaction in CKD. Restoration of peritubular endothelial cell glycolysis in CKD kidney improved microvascular rarefaction and ameliorated fibrotic lesions.