Division of Infectious Genetics, Department of Microbiology and Immunology, University of Tokyo, Minatoku, Tokyo108-8639, Japan.
Int Immunol. 2012 Oct;24(10):613-23. doi: 10.1093/intimm/dxs068. Epub 2012 Jul 25.
AbstractToll-like receptor 5 (TLR5), a sensor for bacterial flagellin, mounts innate and adaptive immune responses, and has been implicated in infectious diseases, colitis and metabolic syndromes. Although TLR5 is believed to belong to cell surface TLRs, cell surface expression has never been verified. Moreover, it has remained unclear which types of immune cells express TLR5 and contribute to flagellin-dependent responses. In this study we established an anti-mouse TLR5 monoclonal antibody and studied the cell surface expression of TLR5 on immune cells. The macrophage cell line J774 expressed endogenous TLR5 on the cell surface and produced IL-6 and G-CSF in response to flagellin. Cell surface expression of TLR5 and flagellin-induced responses were completely abolished by silencing a TLR-specific chaperone protein associated with TLR4 A (PRAT4A), demonstrating that TLR5 is another client of PRAT4A. In the in vivo immune cells, cell surface TLR5 was mainly found on neutrophils and CD11b (hi) Ly6C (hi) classical monocytes in the bone marrow, circulation, spleen and inflammatory lesions. Ly6C (hi) classical monocytes, but not neutrophils, produced cytokines in response to flagellin. Splenic CD8 (-) CD4 (+) conventional dendritic cells and CD11c (hi) CD11b (hi) lamina propria DCs, also clearly expressed cell surface TLR5. Collectively, cell surface expression of TLR5 is dependent on PRAT4A and restricted to neutrophils, classical monocytes and specific DC subsets.
摘要 Toll 样受体 5（TLR5）是细菌鞭毛蛋白的传感器，可引发先天和适应性免疫反应，与传染病、结肠炎和代谢综合征有关。尽管 TLR5 被认为属于细胞表面 TLR，但细胞表面表达从未得到验证。此外，尚不清楚哪些类型的免疫细胞表达 TLR5 并有助于鞭毛蛋白依赖性反应。在这项研究中，我们建立了一种抗小鼠 TLR5 的单克隆抗体，并研究了 TLR5 在免疫细胞上的细胞表面表达。巨噬细胞系 J774 在细胞表面表达内源性 TLR5，并对鞭毛蛋白产生 IL-6 和 G-CSF 反应。沉默与 TLR4A（PRAT4A）相关的 TLR 特异性伴侣蛋白完全消除了 TLR5 的细胞表面表达和鞭毛蛋白诱导的反应，表明 TLR5 是 PRAT4A 的另一个客户。在体内免疫细胞中，细胞表面 TLR5 主要存在于骨髓、循环、脾脏和炎症病变中的中性粒细胞和 CD11b（高）Ly6C（高）经典单核细胞上。Ly6C（高）经典单核细胞而非中性粒细胞对鞭毛蛋白产生细胞因子。脾 CD8（-）CD4（+）常规树突状细胞和 CD11c（高）CD11b（高）固有层 DC 也清楚地表达细胞表面 TLR5。总之，TLR5 的细胞表面表达依赖于 PRAT4A，仅限于中性粒细胞、经典单核细胞和特定的 DC 亚群。
