State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
Infect Immun. 2020 Mar 23;88(4). doi: 10.1128/IAI.00831-19.
The mechanism underlying the pathogenesis of is not fully known. The Nfa34810 protein of has been predicted to be a virulence factor. However, relatively little is known regarding the interaction of Nfa34810 with host cells, specifically invasion and innate immune activation. In this study, we aimed to determine the role of recombinant Nfa34810 during infection. We demonstrated that Nfa34810 is an immunodominant protein located in the cell wall. Nfa34810 protein was able to facilitate the uptake and internalization of latex beads coated with Nfa34810 protein into HeLa cells. Furthermore, the deletion of the gene in attenuated the ability of the bacteria to infect both HeLa and A549 cells. Moreover, stimulation with Nfa34810 triggered macrophages to produce tumor necrosis factor alpha (TNF-α), and it also activated mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways by inducing the phosphorylation of ERK1/2, p38, JNK, p65, and AKT in macrophages. Specific inhibitors of ERK1/2, JNK, and NF-κB significantly reduced the expression of TNF-α, which demonstrated that Nfa34810-mediated TNF-α production was dependent upon the activation of these kinases. We further found that neutralizing antibodies against Toll-like receptor 4 (TLR4) significantly inhibited TNF-α secretion. Taken together, our results indicated that Nfa34810 is a virulence factor of and plays an important role during infection. Nfa34810-induced production of TNF-α in macrophages also involves ERK, JNK, and NF-κB via the TLR4 pathway.
尚未阐明 的发病机制。 的 Nfa34810 蛋白已被预测为一种毒力因子。然而，关于 Nfa34810 与宿主细胞的相互作用，特别是入侵和先天免疫激活，人们知之甚少。在本研究中，我们旨在确定感染过程中重组 Nfa34810 的作用。我们证明 Nfa34810 是一种位于细胞壁中的免疫优势蛋白。Nfa34810 蛋白能够促进涂有 Nfa34810 蛋白的乳胶珠被 HeLa 细胞摄取和内化。此外， 在 中缺失 基因削弱了细菌感染 HeLa 和 A549 细胞的能力。此外，Nfa34810 刺激巨噬细胞产生肿瘤坏死因子-α (TNF-α)，并通过诱导 ERK1/2、p38、JNK、p65 和 AKT 的磷酸化激活丝裂原活化蛋白激酶 (MAPK) 和核因子 κB (NF-κB) 信号通路。ERK1/2、JNK 和 NF-κB 的特异性抑制剂显著降低了 TNF-α 的表达，这表明 Nfa34810 介导的 TNF-α 产生依赖于这些激酶的激活。我们进一步发现，针对 Toll 样受体 4 (TLR4) 的中和抗体显著抑制了 TNF-α 的分泌。总之，我们的结果表明 Nfa34810 是 的一种毒力因子，在感染过程中发挥重要作用。Nfa34810 诱导巨噬细胞产生 TNF-α 也涉及 TLR4 途径中的 ERK、JNK 和 NF-κB。
