School of Medical Laboratory, Tianjin Medical University, Tianjin, 300203, P. R. China.
Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin, 300071, P. R. China.
J Microbiol. 2021 Jul;59(7):681-692. doi: 10.1007/s12275-021-0638-2. Epub 2021 Apr 20.
Listeria monocytogenes (L. monocytogenes) is a Gram-positive intracellular foodborne pathogen that causes severe diseases, such as meningitis and sepsis. The NLR family pyrin domain-containing 3 (NLRP3) inflammasome has been reported to participate in host defense against pathogen infection. However, the exact molecular mechanisms underlying NLRP3 inflammasome activation remain to be fully elucidated. In the present study, the roles of mammalian Ste20-like kinases 1/2 (Mst1/2) and Anaplastic Lymphoma Kinase (ALK) in the activation of the NLRP3 inflammasome induced by L. monocytogenes infection were investigated. The expression levels of Mst1/2, phospho (p)-ALK, p-JNK, Nek7, and NLRP3 downstream molecules including activated cas-pase-1 (p20) and mature interleukin (IL)-1β (p17), were up-regulated in L. monocytogenes-infected macrophages. The ALK inhibitor significantly decreased the expression of p-JNK, Nek7, and NLRP3 downstream molecules in macrophages infected with L. monocytogenes. Furthermore, the Mst1/2 inhibitor markedly inhibited the L. monocytogenes-induced activation of ALK, subsequently downregulating the expression of p-JNK, Nek7, and NLRP3 downstream molecules. Therefore, our study demonstrated that Mst1/2-ALK mediated the activation of the NLRP3 inflammasome by promoting the interaction between Nek7 and NLRP3 via JNK during L. monocytogenes infection, which subsequently increased the maturation and release of proinflammatory cytokine to resist pathogen infection. Moreover, Listeriolysin O played a key role in the process. In addition, we also found that the L. monocytogenes-induced apoptosis of J774A.1 cells was reduced by the Mst1/2 or ALK inhibitor. The present study reported, for the first time, that the Mst1/2-ALK-JNK-NLRP3 signaling pathway plays a vital proinflammatory role during L. monocytogenes infection.
李斯特菌（L. monocytogenes）是一种革兰氏阳性细胞内食源性病原体，可引起脑膜炎和败血症等严重疾病。NLR 家族包含吡喃结构域的 3（NLRP3）炎性小体已被报道参与宿主防御病原体感染。然而，NLRP3 炎性小体激活的确切分子机制仍有待充分阐明。在本研究中，研究了哺乳动物 Ste20 样激酶 1/2（Mst1/2）和间变性淋巴瘤激酶（ALK）在李斯特菌感染诱导的 NLRP3 炎性小体激活中的作用。在李斯特菌感染的巨噬细胞中，Mst1/2、磷酸化（p）-ALK、p-JNK、Nek7 和 NLRP3 下游分子（包括活化的 caspase-1（p20）和成熟的白细胞介素（IL）-1β（p17））的表达水平上调。ALK 抑制剂显著降低了李斯特菌感染的巨噬细胞中 p-JNK、Nek7 和 NLRP3 下游分子的表达。此外，Mst1/2 抑制剂显著抑制李斯特菌诱导的 ALK 激活，随后下调 p-JNK、Nek7 和 NLRP3 下游分子的表达。因此，本研究表明，Mst1/2-ALK 通过 JNK 促进 Nek7 与 NLRP3 之间的相互作用，从而激活 NLRP3 炎性小体，在李斯特菌感染过程中增加促炎细胞因子的成熟和释放以抵抗病原体感染，进而发挥作用。此外，李斯特菌溶素 O 在该过程中起关键作用。此外，我们还发现 Mst1/2 或 ALK 抑制剂可降低李斯特菌诱导的 J774A.1 细胞凋亡。本研究首次报道，Mst1/2-ALK-JNK-NLRP3 信号通路在李斯特菌感染过程中发挥重要的促炎作用。
