TREM-1 is a positive regulator of TNF-α and IL-8 production in U937 foam cells.
The purpose of our study was to investigate the expression levels of TREM-1 (triggering receptor expressed on myeloid cells-1) in U937 foam cells and determine whether TREM-1 regulates the production of tumor necrosis factor-alpha and interleukin-8 in these cells. Human U937 cells were incubated with phorbol 12-myristate 13-acetate and then oxidized human low-density lipoprotein to induce foam cell formation. Oil red O staining was used to identify the foam cells. The production of IL-8 and TNF-α by U937 foam cells was assayed by enzyme-linked immunosorbent assay. The expression of TREM-1 mRNA in U937 foam cells was detected by reverse transcription-polymerase chain reaction. Moreover, U937 foam cells were transfected by small interfering RNA using Lipofectamine 2000 to knockdown TREM-1. Western blot was performed to assay protein expression of TREM-1 and ELISA was used to examine the effect of TREM-1 knockdown on IL-8 and TNF-α production. PMA and ox-LDL induced U937 cells to form foam cells. The production of TNF-α and IL-8 was found to be significantly elevated in U937 foam cells, concomitant with a significant up-regulation of TREM-1 mRNA. TREM-1 siRNA was able to partially silence the expression of TREM-1 protein and remarkably inhibited TNF-α and IL-8 production in U937 foam cells, suggesting that TREM-1 is a positive regulator of TNF-α and IL-8 production in U937 foam cells. Our finding that TREM-1 controls the production of IL-8 and TNF-α in U937 foam cells defines a potentially critical role of TREM-1 in the pathogenesis of atherosclerosis and implicates TREM-1 as a potential therapeutic target for the disease.
Department of Cardiovascular, First Hospital of Jilin University, 71 Xinmin of Chaoyang district, Changchun 130021, China.
Yu-Shi
YS
Wang
Xiang-Jun
XJ
Li
Wai-Ou
WO
Zhao
D015153:Blotting, Western; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D011971:Receptors, Immunologic / Q000235:genetics / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D000073871:Triggering Receptor Expressed on Myeloid Cells-1; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D020298:U937 Cells
D016209:Interleukin-8; D008077:Lipoproteins, LDL; D008562:Membrane Glycoproteins; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; C408842:TREM1 protein, human; D000073871:Triggering Receptor Expressed on Myeloid Cells-1; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; D013755:Tetradecanoylphorbol Acetate