Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun, Jilin Province, China.
Cell Immunol. 2011;270(2):156-63. doi: 10.1016/j.cellimm.2011.05.002. Epub 2011 May 12.
Autoimmune regulator (Aire) is a transcriptional activator that regulates the ectopic expression of many tissue-restricted antigens in medullary thymic epithelial cells, and that has an important role in the negative selection of autoreactive T cells. However, the roles of Aire expression in peripheral lymphoid tissues and hematopoietic cells, especially monocytes/macrophages, remain poorly understood. In this study, we found that the mRNA and protein expression levels of toll-like receptor (TLR)1, TLR3, and TLR8 were notably up-regulated in a mouse macrophage-like cell line (RAW264.7) stably expressing Aire, while the expression of TLR2, TLR4, TLR5, TLR6, TLR7, and TLR9 were not significantly changed. In addition, the mRNA expression of TLR3 and TLR8 were significantly increased in primary peritoneal macrophages transiently transfected with Aire. Using chromatin immunoprecipitation and a luciferase activity assay, we also found that Aire interacted with the TLR1, TLR3, and TLR8 promoters and increased the luciferase transcriptional activity of these promoters in RAW264.7 cells. Moreover, after stimulation by Pam(3)CSK(4), a TLR1 ligand, and poly(I:C), a TLR3 ligand, we found that the mRNA expression levels of IL-1α, TNFα, iNOS, and IFNα were increased in RAW264.7 cells stably expressing Aire. Together, these data suggest that Aire has a crucial role in the recognition of pathogenic microorganisms and peripheral immune tolerance in antigen-presenting cells (APCs) by regulating the expression of TLRs.
自身免疫调节因子 (Aire) 是一种转录激活因子，可调节髓质上皮细胞中许多组织受限抗原的异位表达，在自身反应性 T 细胞的阴性选择中具有重要作用。然而，Aire 在外周淋巴组织和造血细胞（尤其是单核细胞/巨噬细胞）中的表达作用仍知之甚少。在这项研究中，我们发现，在稳定表达 Aire 的小鼠巨噬样细胞系 (RAW264.7) 中，Toll 样受体 (TLR)1、TLR3 和 TLR8 的 mRNA 和蛋白表达水平显著上调，而 TLR2、TLR4、TLR5、TLR6、TLR7 和 TLR9 的表达没有明显变化。此外，Aire 瞬时转染的原代腹腔巨噬细胞中 TLR3 和 TLR8 的 mRNA 表达也显著增加。通过染色质免疫沉淀和荧光素酶活性测定，我们还发现 Aire 与 TLR1、TLR3 和 TLR8 启动子相互作用，并增加了 RAW264.7 细胞中这些启动子的荧光素酶转录活性。此外，在用 TLR1 配体 Pam(3)CSK(4)和 TLR3 配体 poly(I:C)刺激后，我们发现稳定表达 Aire 的 RAW264.7 细胞中 IL-1α、TNFα、iNOS 和 IFNα 的 mRNA 表达水平增加。总之，这些数据表明，Aire 通过调节 TLRs 的表达在抗原呈递细胞 (APC) 中对致病微生物的识别和外周免疫耐受具有重要作用。
