NDT Advance Access originally published online on September 2, 2005
Nephrology Dialysis Transplantation 2006 21(1):101-106; doi:10.1093/ndt/gfi068
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© The Author [2005]. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
Original Articles: Clinical Nephrology
Cellular cholesterol efflux to plasma from proteinuric patients is elevated and remains unaffected by antiproteinuric treatment
1 Department of Internal Medicine, Division of Nephrology and 2 Division of Endocrinology, University Medical Center Groningen, Groningen, The Netherlands, 3 Department of Cell Biology & Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands, 4 Department of Experimental Hepatology, Academic Medical Center, Amsterdam, The Netherlands
Correspondence and offprint requests to: L. Vogt, MD, Department of Internal Medicine, Division of Nephrology, room 4.045, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9718 NX Groningen, The Netherlands. Email: liffertvogt{at}hotmail.com
Background. Lipid derangements are assumed to contribute to the elevated cardiovascular risk in proteinuric patients. The impact of proteinuria on reverse cholesterol transport (RCT) is unknown. The first step in RCT, cellular cholesterol efflux to plasma, may be altered in proteinuria, consequent to changes in pre-ß high-density lipoprotein (HDL) formation and plasma phospholipid transfer protein (PLTP) activity.
Methods. In six non-diabetic male patients with nephrotic-range proteinuria and 12 matched healthy men, plasma (apo)lipoproteins, pre-ß HDL formation, PLTP activity as well as the ability of plasma to promote cholesterol efflux out of cultured human skin fibroblasts were determined. These variables were also measured in response to antiproteinuric treatment, consisting of single and dual RAAS blockade by losartan and lisinopril.
Results. Plasma total cholesterol (P<0.05), triglycerides (P<0.05), apolipoprotein (apo) A-I (P<0.001), apo B (P<0.001), PLTP activity (P<0.005) and pre-ß HDL formation (P<0.001) were higher in proteinuric patients. Cellular cholesterol efflux to plasma from proteinuric patients was 41% higher than to plasma from healthy subjects (P<0.001). Reduction of proteinuria from 5.0 to 1.4 g/day by dual RAAS blockade was associated with a 23% reduction in plasma apo B levels (P<0.05). Pre-ß HDL formation and plasma PLTP activity did not change significantly. Combined antiproteinuric treatment did not reduce the elevated cellular cholesterol efflux.
Conclusion. Cellular cholesterol efflux to plasma from patients with nephrotic-range proteinuria is enhanced, in conjunction with elevated pre-ß HDL formation and plasma PLTP activity. These changes may attenuate the cardiovascular risk associated with proteinuria-associated hyperlipidaemia. Antiproteinuric therapy lowers plasma apo B, but does not affect cell-derived cholesterol efflux, suggesting that this therapy beneficially affects cardiovascular risk in proteinuric patients.
Keywords: apolipoproteins; cellular cholesterol efflux; dual RAAS blockade; PLTP; pre-ß HDL; proteinuria