Abstract
Background:
Functional abnormalities of high-density lipoprotein (HDL) and elevated concentration of low-density lipoprotein (LDL) could contribute to cardiovascular disease (CVD) in chronic kidney disease (CKD) patients. Both qualitative and quantitative changes in HDL have been described in patients with CKD. Specifically, HDL abundance is reduced and HDL acquires a pro-inflammatory properties. In this study, we hypothesized that a functioning kidney transplant reduces serum nitrated apoA-I concentration.
Methods:
Concentrations of nitrated apoA-I, nitrated apoB, total apoA-I and total apoB were measured using indirect sandwich ELISA on sera collected from each transplant subject pre-transplant and at 1, 3, and 12 months post-transplant. Patients were excluded if they had a history of diabetes, prednisone dose > 15 mg/day, nephrotic range proteinuria, serum creatinine (Cr) > 1.5mg/dL or active inflammatory disease, or were treated with lipid-lowering medication or HIV protease inhibitors. Paired values of percent nitrated Apo A-I or nitrated apoB before and after kidney transplantation were compared using Wilcoxon signed rank sum test.
Results:
We screened 75 transplant patients, and 14 were found to meet the selection criteria. Amongst these patients, twelve and eight patients had Cr < 1.5 mg/dL at 3 and 12 months post-transplant, respectively. There was a significant reduction in % nitrated apoA-I at 12 months post-transplant compared to pre-transplant values in patients with Cr<1.5 mg/dL (p=0.04) but neither at 3 months post-transplant nor in patients with Cr >1.5. Reduction of nitrated apoA-I was associated with slight increase in HDL levels 12 months post-transplantation. In contrast to apoA-I, there was no significant change in % nitrated apoB at 3 months and 12 months post-transplant. No significant corelation was observed between nitrated lipoproteins and CRP levels.
Conclusion:
Patients with well functioning grafts had significant reduction in percent nitrated apoA-I without any effect on apoB nitration 12 months after kidney transplantation. Further studies are needed in a large cohort to determine if nitrated apoA-I can be used as a valuable marker for cardiovascular risk stratification in CKD.