Department of Pathology, University College Cork, National University of Ireland, Cork, Ireland;
J Immunol. 2013 Dec 15;191(12):6084-92. doi: 10.4049/jimmunol.1203245. Epub 2013 Nov 6.
Listeria monocytogenes is a Gram-positive bacterium that can cause septicemia and meningitis. TLRs are central receptors of the innate immune system that drive inflammatory responses to invading microbes such as L. monocytogenes. Although intestinal epithelial cells (IECs) represent the initial point of entry used by L. monocytogenes for infection, the innate immune response to L. monocytogenes in these cells has been poorly characterized to date. The aim of this study was to determine which TLRs are involved in mediating the immune response to L. monocytogenes in IECs. We performed an RNA interference screen of TLRs 1-10 in the HT-29 IEC cell line and observed the most significant reduction in chemokine output following silencing of TLR10. This effect was also observed in the macrophage cell line THP-1. The chemokines CCL20, CCL1, and IL-8 were reduced following knockdown of TLR10. Silencing of TLR10 resulted in increased viability of L. monocytogenes in both HT-29 and THP-1 cells. TLR10 was found to be predominantly expressed intracellularly in epithelia, and activation required viable L. monocytogenes. NF-κB activation was seen to require TLR2 in addition to TLR10. Taken together, these data indicate novel roles for TLR10 in sensing pathogenic infection in both the epithelium and macrophages and have identified L. monocytogenes as a source of ligand for the orphan receptor TLR10.
李斯特菌是一种革兰氏阳性细菌，可引起败血病和脑膜炎。TLRs 是先天免疫系统的核心受体，可驱动对李斯特菌等入侵微生物的炎症反应。尽管肠上皮细胞 (IECs) 是李斯特菌感染的初始进入点，但迄今为止，这些细胞中对李斯特菌的先天免疫反应仍未得到充分描述。本研究旨在确定 TLRs 在介导 IECs 对李斯特菌的免疫反应中所起的作用。我们在 HT-29 IEC 细胞系中对 TLRs 1-10 进行了 RNA 干扰筛选，并观察到 TLR10 沉默后趋化因子的产生明显减少。在巨噬细胞系 THP-1 中也观察到了这种效应。CCL20、CCL1 和 IL-8 等趋化因子在 TLR10 沉默后减少。TLR10 沉默导致 HT-29 和 THP-1 细胞中李斯特菌的存活率增加。TLR10 主要在上皮细胞的细胞内表达，其激活需要活的李斯特菌。NF-κB 的激活除了 TLR10 还需要 TLR2。综上所述，这些数据表明 TLR10 在识别上皮细胞和巨噬细胞中的致病性感染方面具有新的作用，并确定李斯特菌是孤儿受体 TLR10 的配体来源。
