Mechanisms of increased expression of toll-like receptor-4 in human monocyte/macrophage-derived foam cells.
The mechanisms of increased expression of toll-like receptor 4 (TLR-4) during the formation of foam cells were explored. Low density lipoprotein (LDL) was prepared by density gradient ultracentrifugation and oxidized by incubation with CuCl2. The human monocytic leukemia cell line (THP-1) was cultured in RPMI1640. The differentiation of THP-1 cells into macrophages (MPs) was induced by using myristate acetate (PMA) for 48 h. The macrophages were then incubated with oxidized LDL (ox-LDL) to generate foam cells (FCs). The mRNA and protein expression levels of human TLR-4 were detected by immunocytochemistry, Western blotting and reverse transcription polymerase chain reaction (RT-PCR). The results showed that the TLR-4 mRNA and the protein expression levels were significantly increased during the differentiation of monocytes into macrophages (P < 0.05) as well as during the formation of lipid-laden foam cells (P < 0.05). It was concluded that the upregulation of human TLR-4 gene expression during the differentiation of monocytes into macrophages and the differentiation of macrophages into foam cells could increase TLR-4 protein synthesis dramatically, which may enhance the ability of foam cells inflammation reaction in atherosclerosis.
Cheng
Bei
B
Department of Gerontology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Yu
Qizhen
Q
Bai
Zhifeng
Z
Ke
Li
L
He
Ping
P
D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D005487:Foam Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007948:Leukemia, Monocytic, Acute / Q000473:pathology; D008077:Lipoproteins, LDL / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
D008077:Lipoproteins, LDL; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C099252:oxidized low density lipoprotein; D013755:Tetradecanoylphorbol Acetate