Targeted Metabolomics Study of Human Plasma Revealed Activation of the Cytochrome P450 Epoxygenase/Epoxide Hydrolase Axis in Patients with IgA Nephropathy.

IgA nephropathy (IgAN) is the most common primary glomerulonephritis and a leading cause of chronic kidney disease. The pathogenic mechanism of IgAN remains largely unknown and thus a specific therapeutic target is lacking. Here, we reported that the cytochrome P450 (CYP) epoxygenase/epoxide hydrolase (EH) axis was activated in the patients and is likely a therapeutic target for IgAN. Specifically, quantitative profiling of the plasma from IgAN patients and healthy controls revealed significant changes in plasma levels of CYP/EH-mediated lipid epoxides and diols. Subsequently, CYP2C8 , CYP2C18 , CYP2J2 , EPHX1 , and EPHX2 were found to be significantly increased in whole blood cells at mRNA levels from the IgAN patients when compared with those of healthy controls. Immunohistochemical analysis showed that all five CYPs and two EHs were upregulated in the kidney tissue from IgAN patients when compared with normative renal tissue, but the expression locations of the proteins were different with most of them. Treatment of HK-2 cells with IgA1 increased cell viability, compressed cell apoptosis, and increased the protein levels of CYP2C9, EPHX1, and EPHX2. All the results agreed that CYPs/EHs axis is likely the prophylactic and therapeutic target for IgAN, providing IgAN patients with a new intervention strategy.