Abstract: TH-PO1160
Erythrocyte S1P Liberates O2 to Block Reciprocal Hypoxia-Inducible Factor (HIF)-1α-Creatine Kinase B-Dependent Profibrotic Macrophage Polarization in CKD
Session Information
- CKD: Mechanisms, AKI, and Beyond - 1
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2303 CKD (Non-Dialysis): Mechanisms
Authors
- Xie, Tingting, Xiangya Hospital Central South University, Changsha, Hunan, China
- Qi, Hao, Xiangya Hospital Central South University, Changsha, Hunan, China
- Dai, Piaoyu, Xiangya Hospital Central South University, Changsha, Hunan, China
- Chen, Changhan, Xiangya Hospital Central South University, Changsha, Hunan, China
- Yiyan, Wang, Xiangya Hospital Central South University, Changsha, Hunan, China
- Li, Zhenjiang, Xiangya Hospital Central South University, Changsha, Hunan, China
- D'Alessandro, Angelo, University of Colorado Anschutz Medical Campus School of Medicine, Aurora, Colorado, United States
- Kellems, Rodney Eugene, The University of Texas Health Science Center at Houston John P and Katherine G McGovern Medical School, Houston, Texas, United States
- Zhang, Weiru, Xiangya Hospital Central South University, Changsha, Hunan, China
- Xia, Yang, Xiangya Hospital Central South University, Changsha, Hunan, China
Background
Hypoxia and immunometabolism disruption are hallmarks of chronic kidney disease (CKD). Erythrocytes are not only the sole cells delivering O2 but also a vital source of the bioactive immune regulator sphingosine 1-phosphate (S1P). However, how erythrocyte-derived O2 and S1P orchestrates renal immunometabolism in CKD remains unexplored.
Methods
To investigate this, mice with erythrocyte-specific ablation of sphingosine kinase1 (eSphK1-/-), the enzyme responsible for producing S1P in erythrocytes, were generated and studied in two CKD models: angiotensin II (Ang II) infusion and unilateral ureteral obstruction (UUO). A Comprehensive approach involving unbiased metabolomics, isotopic arginine flux, immunofluorescence, biochemical assays, genetic studies, and preclinical experiments was used.
Results
Genetic ablation of erythrocyte Sphk1 reduced S1P and O2 delivery, leading to severe renal hypoxia, damage and fibrosis in Ang II induced CKD mouse model. Despite half reduction in plasma S1P, eSphk1-/- mice exhibited elevated pro-fibrotic macrophages surrounding the hypoxic renal tubules and increased renal S1P. Metabolic profiling of purified renal macrophages revealed decreased amino acids and fatty acids, but increased creatine and phosphocreatine. This was validated in vitro using 13C6,15N4-labeled arginine showing that hypoxia increased 13C2-labeled creatine in murine bone marrow-derived macrophages time-dependently. Mechanistically, high S1P level in renal hypoxic microenvironment facilitates HIF-1α phosphorylation and stabilization via S1PR3-PKC signaling. Reciprocally, HIF-1α-CKB (creatine kinase B, key enzyme for creatine phosphate shuttle) supported ATP generation for PKC phosphorate HIF-1α and also energy for profibrotic macrophage polarization. Chrysin rescued the severe renal damage in eSphk1-/- UUO mice and also macrophage-specific CKB ablation through adeno-associated virus attenuate profibrotic macrophage polarization and renal fibrosis in UUO mice.
Conclusion
Our work uncovered an erythrocyte-macrophage metabolic circuit driving renal fibrosis via S1P-S1PR3-PKC-HIF-1α-CKB mediated sustained HIF-1α activation, offering new therapeutic strategies for fibrosis and other hypoxia-associated disorders.
Funding
- Government Support – Non-U.S.