CD14 and TLR4 mediate cytokine release promoted by electronegative LDL in monocytes
Por:
Estruch, M, Bancells, C, Beloki, L, Sanchez-Quesada, JL, Ordonez-Llanos, J, Benitez, S
Publicada:
1 ago 2013
Resumen:
Aims: Electronegative LDL (LDL(-)), a minor modified LDL present in the circulation, induces cytokine release in monocytes. We aimed to determine the role of the receptor CD14 and toll-like receptors 2 and 4 (TLR2, TLR4) in the inflammatory action promoted by LDL(-) in human monocytes.
Methods and results: Monocytes were preincubated with antibodies to neutralize CD14, TLR2 and TLR4. The release of monocyte chemoattractant protein 1 (MCP1), and interleukin 6 and 10 (IL6 and IL10) promoted by LDL(-) was inhibited 70-80% by antiCD14 and antiTLR4, and 15-25% by antiTLR2. The involvement of CD14 and TLR4 was confirmed by gene silencing experiments. The human monocytic THP1 cell line overexpressing CD14 released more cytokines in response to LDL(-) than the same THP1 cell line without expressing CD14. VIPER, a specific inhibitor of the TLR4 signaling pathway, blocked 75-90% the cytokine release promoted by LDL(-).
Cell binding experiments showed that monocytes preincubated with neutralizing antibodies presented lesser LDL(-) binding than non-preincubated monocytes The inhibitory capacity was antiCD14>antiTLR4>>antiTLR2. Cell-free experiments performed in CD14-coated microtiter wells confirmed that CD14 was involved in LDL(-) binding.
When LDL(-) and lipopolysaccharide (LPS) were added simultaneously to monocytes, cytokine release was similar to that promoted by LDL(-) alone. Binding experiments showed that LDL(-) and LPS competed for binding to monocytes and to CD14 coated-wells.
Conclusions: CD14 and TLR4 mediate cytokine release induced by LDL(-) in human monocytes. The cross-competition between LPS and LDL(-) for the same receptors could be a counteracting action of LDL(-) in inflammatory situations. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
Filiaciones:
Estruch, M:
Univ Autonoma Barcelona, Dept Bioquim & Biol Mol, E-08193 Barcelona, Spain
Inst Invest Biomed Sant Pau, Barcelona 08025, Spain
Bancells, C:
Univ Autonoma Barcelona, Dept Bioquim & Biol Mol, E-08193 Barcelona, Spain
Inst Invest Biomed Sant Pau, Barcelona 08025, Spain
Beloki, L:
Univ Autonoma Barcelona, Dept Bioquim & Biol Mol, E-08193 Barcelona, Spain
Sanchez-Quesada, JL:
Inst Invest Biomed Sant Pau, Barcelona 08025, Spain
Ordonez-Llanos, J:
Univ Autonoma Barcelona, Dept Bioquim & Biol Mol, E-08193 Barcelona, Spain
Benitez, S:
Inst Invest Biomed Sant Pau, Barcelona 08025, Spain
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