Role of cytochrome P450 2C8 and 2J2 genotypes in calcineurin inhibitor-induced chronic kidney disease

Abstract

Objectives: The calcineurin inhibitors (CNIs) cyclosporine A (CsA) and tacrolimus (Tac) help prevent allograft rejection but are associated with nephrotoxicity. Cytochrome P450 2C8 (CYP2C8) and CYP2J2 are polymorphic enzymes expressed in the kidney that metabolize arachidonic acid (AA) to epoxyeicosatrienoic acids, promoting kidney homeostasis. This study examined the association between CNI-induced nephrotoxicity in liver transplant patients and CYP2C8 and CYP2J2 polymorphisms.

Methods: Liver transplantation patients receiving CNIs for at least 3 years were genotyped for CYP2C8*3, CYP2C8*4, CYP2C8 Haplotypes B and C, and CYP2J2*7 and evaluated for nephrotoxicity (serum creatinine > or = 1.6 mg/dl) 3-year post-transplantation. CYP2C8 proteins were also engineered in E. coli and their activity towards AA and inhibition by CNIs was investigated in vitro.

Results: The risk of kidney disease post-transplantation was positively associated with CYP2C8*3 genotype. Odds ratios for all participants carrying at least one CYP2C8*3 allele were significant [odds ratio=2.38 (1.19-4.78)]. Stratification by CNI indicated a significant association between CYP2C8*3 and nephrotoxicity among patients receiving Tac but not CsA. The risk of renal dysfunction was not significantly influenced by CYP2C8*4, CYP2J2*7, or CYP2C8 haplotype B genotypes although inheritance of haplotype C seems to be protective. In vitro, the gene products of CYP2C8*3 and CYP2C8*4 were deficient in AA epoxidation, retaining 26 and 18% of wild-type activity, respectively. Circulating plasma concentrations of CsA and Tac inhibited CYP2C8 wild-type in vitro epoxidation of AA by 17 and 35%, respectively.

Conclusion: Inheritance of CYP2C8*3 is associated with a higher risk of developing renal toxicity in patients treated chronically with CNIs, and especially Tac, possibly by reducing formation of kidney protecting vasodilatory epoxyeicosatrienoic acids.

Figure 1

14,15-EET Formation by CYP2J2 and CYP2C8. Values are reported as the average of two separate experiments

Figure 2

Steady state kinetics for 14,15-EET formation rate by CYP2C8.1 (panel A), CYP2C8.3 (panel B) and CYP2C8.4 (panel C). Data was fitted to a single enzyme Michealis-Menten model. Values are the average of duplicates.

Figure 3

Inhibition of 14, 15-EET Formation by CSA and Tac. The concentration of AA was 5 μM for CYP28 and 10 μM for CYP2J2. The concentrations of CSA and Tac were 0.2 μM and 0.02 μM, respectively. Experiments were run in duplicates and reported as the average.