Zinc-alpha2-glycoprotein modulates blood pressure by regulating renal lipid metabolism reprogramming - mediated urinary Na+ excretion in hypertension

Abstract Aims Organs modulating blood pressure are associated with a common cytokine known as adipokines. We chose Zinc-alpha2-glycoprotein (ZAG) due to its prioritized transcriptional level in the database. Previous studies showed that ZAG is involved in metabolic disorders. The aim of this study was to investigate its role in hypertension. Methods and results Serum ZAG levels were assessed in hypertensive and healthy participants. Blood pressure was monitored in Azgp1−/− mice and other animal models by 24-hour ambulatory implanted telemetric transmitters and tail-cuff method. Multi-omics analysis of proteomics and metabolomics were performed to explore possible mechanisms. Serum ZAG levels were significantly decreased and associated with morning urine Na+ excretion in hypertensive participants in a cross-sectional study. This study firstly reported that Azgp1−/− mice exhibited increased blood pressure and impaired urinary Na+ excretion, which were restored by AAV9-mediated renal tubule Azgp1 rescue. Azgp1 knockout caused the reprogramming of renal lipid metabolism, and increased Na+/H+-exchanger (NHE) activity in the renal cortex. Administration with a NHE inhibitor EIPA reversed the impaired urinary Na+ excretion in Azgp1−/− mice. Moreover, the activity of carnitine palmitoyltransferase 1 (CPT1), a key enzyme of fatty acid β-oxidation, was decreased, and the levels of malonyl-CoA, an inhibitor of CPT1, were increased in renal cortex of Azgp1−/− mice. Renal Cpt1 rescue improved urinary Na+ excretion and blood pressure in Azgp1−/− mice, accompanied by decreased renal fatty acid levels and NHE activity. Finally, administration of recombinant ZAG protein improved blood pressure and urinary Na+ excretion in spontaneous hypertension rats. Conclusion Deficiency of Azgp1 increased the malonyl CoA-mediated inhibition of CPT1 activity, leading to renal lipid metabolism reprogramming, resulting in accumulated fatty acids and increased NHE activity, subsequently decreasing urinary Na+ excretion and causing hypertension. These findings may provide a potential kidney-targeted therapy in the prevention and treatment of hypertension.