Medical University of South Carolina, Charleston.
Arthritis Rheumatol. 2014 Dec;66(12):3436-44. doi: 10.1002/art.38818.
The Fli-1 transcription factor is implicated in the pathogenesis of systemic lupus erythematosus (SLE), both in humans and in animal models. Dysregulation of interleukin-6 (IL-6) is also associated with SLE. The purpose of this study was to investigate whether Fli-1 directly regulates the expression of IL-6.
Sera were collected from wild-type and Fli-1-heterozygous (Fli-1(+/-) ) MRL/lpr mice, and the concentration of IL-6 was measured by enzyme-linked immunosorbent assay (ELISA). Expression of IL-6 in the kidney was measured by real-time polymerase chain reaction analysis. T cells were isolated from wild-type and Fli-1(+/-) MRL/lpr mice and stimulated with CD3/CD28 beads, and the concentration of IL-6 in the supernatants was measured by ELISA. MS1 endothelial cells were transfected with Fli-1 and control small interfering RNA, and the production of IL-6 was compared after lipopolysaccharide stimulation. A chromatin immunoprecipitation (ChIP) assay was performed to determine whether Fli-1 binds to the IL-6 promoter region. Transient transfections with the NIH3T3 cell line were performed to examine whether Fli-1 regulates the expression of IL-6.
Fli-1(+/-) MRL/lpr mice had significantly decreased IL-6 levels in sera and reduced expression of IL-6 in kidneys as compared to their wild-type littermates. T cells isolated from Fli-1(+/-) MRL/lpr mice produced less IL-6 than did those from wild-type mice. Inhibiting the expression of Fli-1 in endothelial cells resulted in reduced production of IL-6. The ChIP assay revealed direct binding of Fli-1 to 3 regions within the IL-6 promoter. Fli-1 activated transcription from the IL-6 promoter in a dose-dependent manner.
The direct regulation of IL-6 expression by Fli-1 represents one possible mechanism for the protective effect of decreased Fli-1 expression in lupus.
Fli-1 转录因子在系统性红斑狼疮（SLE）的发病机制中起作用，在人类和动物模型中都是如此。白细胞介素-6（IL-6）的失调也与 SLE 有关。本研究旨在探讨 Fli-1 是否直接调节 IL-6 的表达。
收集野生型和 Fli-1 杂合（Fli-1(+/-)）MRL/lpr 小鼠的血清，通过酶联免疫吸附试验（ELISA）测量 IL-6 的浓度。通过实时聚合酶链反应分析测量肾脏中 IL-6 的表达。从野生型和 Fli-1(+/-)MRL/lpr 小鼠中分离 T 细胞，并用 CD3/CD28 珠刺激，通过 ELISA 测量上清液中 IL-6 的浓度。用 Fli-1 和对照小干扰 RNA 转染 MS1 内皮细胞，比较脂多糖刺激后的 IL-6 产生。进行染色质免疫沉淀（ChIP）实验以确定 Fli-1 是否与 IL-6 启动子区域结合。用 NIH3T3 细胞系进行瞬时转染，以检查 Fli-1 是否调节 IL-6 的表达。
与野生型同窝仔相比，Fli-1(+/-)MRL/lpr 小鼠血清中 IL-6 水平显著降低，肾脏中 IL-6 表达减少。从 Fli-1(+/-)MRL/lpr 小鼠中分离的 T 细胞产生的 IL-6 少于从野生型小鼠中分离的 T 细胞。在内皮细胞中抑制 Fli-1 的表达导致 IL-6 产生减少。ChIP 实验显示 Fli-1 直接结合 IL-6 启动子的 3 个区域。Fli-1 以剂量依赖的方式激活 IL-6 启动子的转录。
Fli-1 对 IL-6 表达的直接调节代表了 Fli-1 表达减少在狼疮中具有保护作用的一种可能机制。
