Inflammation and dyslipidaemia both play important roles in the development of glomerular atherosclerosis in renal diseases. We have demonstrated that inflammatory mediators induced Scr (scavenger receptor) expression and the formation of foam cells, and that AP-1 (activator protein 1)/ets were necessary transcriptional factors for Scr induction in HMCs (human kidney mesangial cells). Most cells are protected from excessive native LDL (low-density lipoprotein) accumulation by tight feedback regulation of the LDLr (LDL receptor). However, we observed that HMCs formed foam cells via the LDLr pathway when incubated with IL-1β (interleukin-1β; 5 ng/ml) and unmodified LDL (200 μg/ml), suggesting that inflammatory mediators may disrupt the cholesterol-mediated feedback regulation. This feedback involves cholesterol-mediated down-regulation of LDLr controlled by SCAP [SREBP (sterol responsive element-binding protein) cleavage-activating protein]. We have also demonstrated that both tumour necrosis factor α and IL-1β increased nuclear SREBP-1 levels by increasing SCAP mRNA expression, even in the presence of a high concentration of LDL. Since intracellular lipid content is governed by both influx and efflux mechanisms, we set out to examine the impact of inflammatory cytokines on cholesterol efflux, a process mediated by the protein ABCA1 (ATP binding cassette A1). IL-1β inhibited [3H]cholesterol efflux from HMCs by inhibition of the peroxisome-proliferator-activated receptor/LXR (liver X receptor)/ABCA1 pathway. Taken together, our results suggest that inflammatory mediators increase lipid accumulation in HMCs not only by promoting increased lipoprotein uptake by Scr and LDLr, but also by inhibiting ABCA1-mediated cholesterol efflux to high-density lipoprotein.
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Conference Article|
February 01 2004
Regulation of lipoprotein trafficking in the kidney: role of inflammatory mediators and transcription factors
X.Z. Ruan;
X.Z. Ruan
1
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
1To whom correspondence should be addressed (e-mail xzruan@rfc.ucl.ac.uk).
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J.F. Moorhead;
J.F. Moorhead
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
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R. Fernando;
R. Fernando
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
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D.C. Wheeler;
D.C. Wheeler
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
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S.H. Powis;
S.H. Powis
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
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Z. Varghese
Z. Varghese
Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, U.K.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2004 Biochemical Society
2004
Biochem Soc Trans (2004) 32 (1): 88–91.
Citation
X.Z. Ruan, J.F. Moorhead, R. Fernando, D.C. Wheeler, S.H. Powis, Z. Varghese; Regulation of lipoprotein trafficking in the kidney: role of inflammatory mediators and transcription factors. Biochem Soc Trans 1 February 2004; 32 (1): 88–91. doi: https://doi.org/10.1042/bst0320088
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