- 作者：Montserrat Estruch ; Cristina Bancells ; Lorea Beloki ; Jose Luis Sanchez-Quesada ; Jordi Ord¨®?ez-Llanos ; Sonia Benitez
- 关键词：Electronegative LDL ; CD14 ; Toll-like receptors ; Monocytes ; Lipopolysaccharide
- 刊名：Atherosclerosis
- 出版年：2013
- 出版时间：August, 2013
- 年：2013
- 卷：229
- 期：2
- 页码：356-362
- 全文大小：472 K
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.