Institute of Clinical Microbiology, Immunology and Hygiene, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg Erlangen, Germany.
Front Immunol. 2013 Jan 24;4:5. doi: 10.3389/fimmu.2013.00005. eCollection 2013.
The world's most successful intracellular bacterial pathogen, Mycobacterium tuberculosis (MTB), survives inside macrophages by blocking phagosome maturation and establishes chronic infection characterized by the formation of granulomas. Trehalose-6,6-dimycolate (TDM), the mycobacterial cord factor, is the most abundant cell wall lipid of virulent mycobacteria, is sufficient to cause granuloma formation, and has long been known to be a major virulence factor of MTB. Recently, TDM has been shown to activate the Syk-Card9 signaling pathway in macrophages through binding to the C-type lectin receptor Mincle. The Mincle-Card9 pathway is required for activation of macrophages by TDM in vitro and for granuloma formation in vivo following injection of TDM. Whether this pathway is also exploited by MTB to reprogram the macrophage into a comfortable niche has not been explored yet. Several recent studies have investigated the phenotype of Mincle-deficient mice in mycobacterial infection, yielding divergent results in terms of a role for Mincle in host resistance. Here, we review these studies, discuss possible reasons for discrepant results and highlight open questions in the role of Mincle and other C-type lectin receptors in the infection biology of MTB.
世界上最成功的细胞内细菌病原体结核分枝杆菌(MTB)通过阻止吞噬体成熟在巨噬细胞内存活,并建立以肉芽肿形成为特征的慢性感染。海藻糖-6,6-二没食子酸酯(TDM)是毒力分枝杆菌中最丰富的细胞壁脂质,足以引起肉芽肿形成,长期以来一直被认为是 MTB 的主要毒力因子。最近,TDM 已被证明通过与 C 型凝集素受体 Mincle 结合,在巨噬细胞中激活 Syk-Card9 信号通路。Mincle-Card9 通路是 TDM 在体外激活巨噬细胞以及在体内注射 TDM 后形成肉芽肿所必需的。该途径是否也被 MTB 利用将巨噬细胞重新编程为舒适的小生境尚未得到探索。最近的几项研究调查了 Mincle 缺陷小鼠在分枝杆菌感染中的表型,在 Mincle 对宿主抗性中的作用方面得出了不同的结果。在这里,我们回顾这些研究,讨论结果不一致的可能原因,并强调 Mincle 和其他 C 型凝集素受体在 MTB 感染生物学中的作用中的悬而未决的问题。