Si-Chan Sung1, Koanhoi Kim2, Kyeong-Ah Lee2, Kyung-Ha Choi2, Sung‐Han Kim2, Yonghae Son2, Yuseok Moon3, Seong Kug Eo4, Byung Yong Rhim2
1Departments of Thoracic and Cardiovascular Surgery
2Pharmacology, and
3Microbiology, School of Medicine, Pusan National University, Busan, and
4Laboratory of Microbiology, College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Jeonju, Korea
Tóm tắt
This study investigated the effects of 7-ketocholesterol on interleukin (IL)-6 expression in vascular smooth muscle cells (VSMC). Among the 7 IL examined, only IL-6 transcript was increased by 7-ketocholesterol treatment in human aorta smooth muscle cells. IL-6 transcripts increased up to 24 h after treatment with 7-ketocholesterol, and this effect was profoundly repressed by treatment with p38 MAPK inhibitors and to a lesser extent JNK inhibitors. 7α-Hydroxycholesterol, 27-hydroxycholesterol or cholesterol, however, did not induce IL-6 expression. Mechanisms of IL-6 induction by 7-ketocholesterol were investigated in comparison with tumor necrosis factor (TNF)-α. Whereas TNF-α activated IL-6 promoter, which was impaired by p38 MAPK inhibitors or by mutation in the NF-κB-binding site within the promoter region, 7-ketocholesterol did not affect IL-6 promoter activity. Instead, this oxysterol slowed degradation of IL-6 mRNA and increased the amount of cytoplasmic HuR. 7-ketocholesterol significantly increased the amount of intracellular IL-6 protein in the presence of brefeldin A. 7-Ketocholesterol also enhanced IL-6 release from VSMC. IL-6 release by 7-ketocholesterol, although significant, was not as remarkable as that induced by TNF-α. These data suggest that 7-ketocholesterol upregulates IL-6 via mechanisms distinct from TNF-α and contributes to the intra- and extracellular IL-6 deposits within the vasculature.
