Enhanced gene expression of scavenger receptor in peripheral blood monocytes from patients on cuprophane haemodialysis

Abstract

Macrophage scavenger receptor (SR) is implicated in playing a key role in macrophage-derived foam cell formation by taking up a large amount of modified low-density lipoproteins (LDL). It has also been postulated that alpha 2-macroglobulin receptor/LDL receptor-related protein (alpha 2MG/LRP) is involved in the development of foam cells by taking up apo E-enriched chylomicrons and VLDL remnants, and lipoprotein lipase-triglyceride-rich lipoprotein complexes. Accumulation of these lipid-loaded monocyte/ macrophages in the subendothelial space is considered to be an early event of atherogenesis. Since atherogenesis is considered to be accelerated in dialysis patients, we attempted to investigate whether gene expression of SR and alpha 2MG/LRP are altered in peripheral blood monocytes from patients on haemodialysis with a cuprophane (Cu) or polymethylmethacrylate (PMMA) membranes. Peripheral blood monocytes (PBM) were prepared from patients undergoing haemodialysis with a Cu membrane (n = 9), patients undergoing haemodialysis with a PMMA membrane (n = 9), and healthy controls (n = 7). In a separate experiment we examined SR gene expression in uraemic patients (n = 12) and healthy controls (n = 9). SR and alpha 2MG/LRP mRNA were semiquantitated using reverse-transcription polymerase chain reaction (RT-PCR) assay followed by Southern blotting. SR mRNA expression in PBM from patients on chronic haemodialysis with a Cu membrane was about twofold higher than that in PBM from patients on chronic haemodialysis with a PMMA membrane or the controls (P < 0.05). alpha 2MG/LRP mRNA expression in PBM showed no difference among these, three groups. SR gene expression in monocytes from uraemic patients was not increased compared with that in the controls. PBM from patients under Cu membrane dialysis showed higher gene expression of SR than patients under PMMA membrane dialysis, uraemic patients, or healthy controls. This increased gene expression of SR in monocytes may be associated with the pathogenesis of accelerated atherosclerosis in patients on dialysis with a Cu membrane.