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Enhanced scavenger receptor expression in monocyte-macrophages in dialysis patients
M Ando1, I Lundkvist, J Bergström
1Division of Renal Medicine, Baxter Novum Research Laboratory, Huddinge University Hospital, Karolinska Institute, Huddinge, Sweden.
Abstract:
The macrophage scavenger receptor (SR), which has two isoforms named type I and II, plays a leading role in the atherosclerotic process. To elucidate the mechanism of atherosclerosis in dialysis patients, SR expression was studied in monocyte-macrophages from thirteen dialysis patients and eight healthy controls. SR mRNA expression was examined in four hemodialysis patients and four controls matched for age and sex. Monocytes were allowed to differentiate into macrophages in in vitro cultures for seven days and SR type I and II mRNA expression were analyzed with the reverse transcription-polymerase chain reaction and quantitated using radiation densities of Southern blots. Only SR type I expression increased during differentiation and was accelerated by one or two days and enhanced after five days in patients, as compared to controls. To detect SR protein expression, uptake of fluorescently labeled acetylated low-density lipoprotein (Ac-LDL) was evaluated by flow cytometry. The mean fluorescence intensity of labeled cells was significantly higher in hemodialysis and continuous ambulatory peritoneal dialysis patients than in controls, although the number of SR-positive cells remained constant. In conclusion, SR expression is enhanced in macrophages from dialysis patients, probably by up-regulation of type I, which may contribute to the development of atherosclerosis in these patients.
Insights
Macrophage scavenger receptor (SR) expression is elevated in dialysis patients, particularly type I, potentially driving atherosclerosis development. This study investigated SR in macrophages from dialysis patients versus healthy controls.
Area of Science:
- Biomedical Science
- Immunology
- Cardiovascular Research
Background:
- Atherosclerosis is a major concern in dialysis patients.
- Macrophage scavenger receptors (SR) are implicated in atherosclerotic processes.
- Understanding SR in dialysis patients is crucial for elucidating atherosclerosis mechanisms.
Purpose of the Study:
- To investigate macrophage scavenger receptor (SR) expression in dialysis patients.
- To compare SR expression in macrophages from dialysis patients and healthy controls.
- To determine the role of SR isoforms in atherosclerosis development in dialysis patients.
Main Methods:
- Monocytes from 13 dialysis patients and 8 controls were differentiated into macrophages in vitro.
- SR type I and II mRNA expression was analyzed using reverse transcription-polymerase chain reaction (RT-PCR) and Southern blots.
- SR protein expression was assessed by evaluating acetylated low-density lipoprotein (Ac-LDL) uptake via flow cytometry.
Main Results:
- SR type I mRNA expression increased during macrophage differentiation, accelerated in dialysis patients compared to controls.
- Macrophage differentiation showed enhanced SR type I expression after five days in dialysis patients.
- Uptake of labeled Ac-LDL was significantly higher in macrophages from dialysis patients, indicating increased SR protein expression.
Conclusions:
- Macrophage scavenger receptor (SR) expression is enhanced in macrophages from dialysis patients.
- Up-regulation of SR type I likely contributes to increased SR expression.
- Elevated SR expression may promote the development of atherosclerosis in dialysis patients.