Cytochrome P450: The Metabolic Pathways and the Genetic Regulation Involved in Shaping the Story of Diabetic Kidney Disease

Abstract

Introduction: Cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid (AA) into 20-HETE (20-Hydroxyeicosatetraenoic acid) and EETs (Epoxyeicosatrienoic acids). Our group has demonstrated the involvement of CYPs and their metabolites in the pathogenesis of diabetic kidney disease (DKD) by activating reactive oxygen species (ROS) production. Polymorphisms of CYP genes can alter the expression of these enzymes, influencing DKD prognosis. We hypothesize that alterations in 20-HETE and EET levels contribute to ROS elevation via an SGLT2/mTOR-dependent mechanism in diabetes. Additionally, we have assessed the genetic contribution in the AA-metabolizing CYPs associated with the progression of DKD. Methods: We enrolled healthy volunteers and patients with type 2 diabetes (T2DM) with or without DKD. We measured 20-HETE and EET levels in urine by Enzyme Linked Immunosorbent Assay. We also assessed CYP expression in kidney biopsies. SNPs for the CYP4A11, CYP4F8, and CYP2B6 genes were detected using TaqMan PCR assays on DNA extracted from blood samples. To study the preclinical significance, molecular and histological analyses were performed using a T2DM mouse model treated with the pharmacological inhibitors of 20-HETE (HET0016), sEH (AUDA), SGLT2 (Dapagliflozin), and mTOR (Rapamycin, JR-AB2-011 and PP242). In vitro validation studies were performed using human podocyte and proximal tubular epithelial cells. Results: Patients with T2DM had elevated 20-HETE levels compared healthy volunteers. This increase was associated with higher expression of CYP4A11 and CYP4F8 in kidney biopsies. EET levels were lower in T2DM patients, correlating with decreased CYP2B6 expression in kidney biopsies. We identified novel SNPs for CYP2B6 and CYP4A11 in patient groups, suggesting an increased risk with the mutant alleles for diabetes and DKD. Regulation of 20-HETE and EET levels were associated with renal injury mediated by the SGLT2/mTOR/NOX4 axis. This was confirmed in the T2DM mouse mode and validated in the human renal cells. Conclusion: This study provides a framework into novel CYP450 pathways involved in diabetes-induced renal injury. We also describe the potential prognostic and diagnostic biomarkers related to CYP associated pathways in the progression DKD.