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Interleukin-1 beta and tumour necrosis factor-alpha impede neutral lipid turnover in macrophage-derived foam cells

Persson, Jenny LU ; Nilsson, Jan LU and Lindholm, Marie LU (2008) In BMC Immunology 9.
Abstract
Background: Pro-inflammatory cytokines can affect intracellular lipid metabolism. A variety of effects have been described for different cell types; hepatocyte lipid turnover pathways are inhibited during inflammation, whereas interleukin-1 beta (IL-1 beta) reduces intracellular cholesterol levels in fibroblasts. Levels of the pro-inflammatory cytokines IL-1 beta and tumour necrosis factor-alpha (TNF-alpha) are up-regulated at sites of formation of atherosclerotic plaques. Plaque formation is though to begin with infiltration of monocytes to the intimal layer of the vascular wall, followed by differentiation to macrophages and macrophage uptake of modified lipoproteins, resulting in accumulation of intracellular lipids. The lipid-filled... (More)
Background: Pro-inflammatory cytokines can affect intracellular lipid metabolism. A variety of effects have been described for different cell types; hepatocyte lipid turnover pathways are inhibited during inflammation, whereas interleukin-1 beta (IL-1 beta) reduces intracellular cholesterol levels in fibroblasts. Levels of the pro-inflammatory cytokines IL-1 beta and tumour necrosis factor-alpha (TNF-alpha) are up-regulated at sites of formation of atherosclerotic plaques. Plaque formation is though to begin with infiltration of monocytes to the intimal layer of the vascular wall, followed by differentiation to macrophages and macrophage uptake of modified lipoproteins, resulting in accumulation of intracellular lipids. The lipid-filled cells are referred to as macrophage foam cells, a key feature of atherosclerotic plaques. We have investigated the effects of IL-1 beta and TNF-alpha on macrophage foam cells in order to assess whether presence of the pro-inflammatory cytokines improves or aggravates macrophage foam cell formation by affecting lipid accumulation and lipid turn-over in the cells. Results: Differentiated primary human macrophages or THP-1 cells were lipid loaded by uptake of aggregated low density lipoproteins (AgLDL) or very low density lipoproteins (VLDL), and then incubated with IL-1 beta (0-5000 pg/ml) in lipoprotein-free media for 24 h. Cells incubated in absence of cytokine utilized accumulated neutral lipids, in particular triglycerides. Addition of exogenous IL-1 beta resulted in a dose-dependent retention of intracellular cholesterol and triglycerides. Exchanging IL-1 beta with TNF-alpha gave a similar response. Analysis of fatty acid efflux and intracellular fatty acid activation revealed a pattern of decreased lipid utilization in cytokine-stimulated cells. Conclusion: IL-1 alpha and TNF-alpha enhance macrophage foam cell formation, in part by inhibition of macrophage intracellular lipid catabolism. If present in vivo, these mechanisms will further augment the pro-atherogenic properties of the two cytokines. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
BMC Immunology
volume
9
publisher
BioMed Central
external identifiers
  • wos:000261609900001
  • scopus:57649146879
ISSN
1471-2172
DOI
10.1186/1471-2172-9-70
language
English
LU publication?
yes
id
a8173af3-0e0e-4826-9b93-0ada1e807797 (old id 1305745)
date added to LUP
2009-03-23 10:10:25
date last changed
2017-07-02 03:49:57
@article{a8173af3-0e0e-4826-9b93-0ada1e807797,
  abstract     = {Background: Pro-inflammatory cytokines can affect intracellular lipid metabolism. A variety of effects have been described for different cell types; hepatocyte lipid turnover pathways are inhibited during inflammation, whereas interleukin-1 beta (IL-1 beta) reduces intracellular cholesterol levels in fibroblasts. Levels of the pro-inflammatory cytokines IL-1 beta and tumour necrosis factor-alpha (TNF-alpha) are up-regulated at sites of formation of atherosclerotic plaques. Plaque formation is though to begin with infiltration of monocytes to the intimal layer of the vascular wall, followed by differentiation to macrophages and macrophage uptake of modified lipoproteins, resulting in accumulation of intracellular lipids. The lipid-filled cells are referred to as macrophage foam cells, a key feature of atherosclerotic plaques. We have investigated the effects of IL-1 beta and TNF-alpha on macrophage foam cells in order to assess whether presence of the pro-inflammatory cytokines improves or aggravates macrophage foam cell formation by affecting lipid accumulation and lipid turn-over in the cells. Results: Differentiated primary human macrophages or THP-1 cells were lipid loaded by uptake of aggregated low density lipoproteins (AgLDL) or very low density lipoproteins (VLDL), and then incubated with IL-1 beta (0-5000 pg/ml) in lipoprotein-free media for 24 h. Cells incubated in absence of cytokine utilized accumulated neutral lipids, in particular triglycerides. Addition of exogenous IL-1 beta resulted in a dose-dependent retention of intracellular cholesterol and triglycerides. Exchanging IL-1 beta with TNF-alpha gave a similar response. Analysis of fatty acid efflux and intracellular fatty acid activation revealed a pattern of decreased lipid utilization in cytokine-stimulated cells. Conclusion: IL-1 alpha and TNF-alpha enhance macrophage foam cell formation, in part by inhibition of macrophage intracellular lipid catabolism. If present in vivo, these mechanisms will further augment the pro-atherogenic properties of the two cytokines.},
  articleno    = {70},
  author       = {Persson, Jenny and Nilsson, Jan and Lindholm, Marie},
  issn         = {1471-2172},
  language     = {eng},
  publisher    = {BioMed Central},
  series       = {BMC Immunology},
  title        = {Interleukin-1 beta and tumour necrosis factor-alpha impede neutral lipid turnover in macrophage-derived foam cells},
  url          = {http://dx.doi.org/10.1186/1471-2172-9-70},
  volume       = {9},
  year         = {2008},
}