Department of Infections with Natural Foci, Gamaleya National Research Centre of Epidemiology and Microbiology, Moscow, Russia.
Department of Dusty Plasmas, Joint Institute of High Temperatures RAS, Moscow, Russia.
PLoS One. 2023 Aug 31;18(8):e0290842. doi: 10.1371/journal.pone.0290842. eCollection 2023.
Listeria monocytogenes is motile at 22°C and non-motile at 37°C. In contrast, expression of L. monocytogenes virulence factors is low at 22°C and up-regulated at 37°C. Here, we studied a character of L. monocytogenes near surface swimming (NSS) motility and its effects on adhesion patterns and invasion into epithelial cells. L. monocytogenes and its saprophytic counterpart L. innocua both grown at 22°C showed similar NSS characteristics including individual velocities, trajectory lengths, residence times, and an asymmetric distribution of velocity directions. Similar NSS patterns correlated with similar adhesion patterns. Motile bacteria, including both pathogenic and saprophytic species, showed a preference for adhering to the periphery of epithelial HEp-2 cells. In contrast, non-motile bacteria were evenly distributed across the cell surface, including areas over the nucleus. However, the uneven distribution of motile bacteria did not enhance the invasion into HEp-2 cells unless virulence factor production was up-regulated by the transient shift of the culture to 37°C. Motile L. monocytogenes grown overnight at 22°C and then shifted to 37°C for 2 h expressed invasion factors at the same level and invaded human cells up to five times more efficiently comparatively with non-motile bacteria grown overnight at 37°C. Taken together, obtained results demonstrated that (i) NSS motility and correspondent peripheral location over the cell surface did not depend on L. monocytogenes virulence traits; (ii) motility improved L. monocytogenes invasion into human HEp-2 cells within a few hours after the transition from the ambient temperature to the human body temperature.
李斯特菌在 22°C 时具有运动性，而在 37°C 时不具有运动性。相比之下，李斯特菌的毒力因子在 22°C 时表达水平较低，而在 37°C 时上调。在这里，我们研究了李斯特菌近表面游泳（NSS）运动的特性及其对粘附模式和侵入上皮细胞的影响。在 22°C 下生长的李斯特菌及其腐生对应物无害李斯特菌均表现出相似的 NSS 特征，包括个体速度、轨迹长度、停留时间和速度方向的不对称分布。相似的 NSS 模式与相似的粘附模式相关。运动细菌，包括致病和腐生物种，都倾向于粘附在上皮 HEp-2 细胞的边缘。相比之下，非运动细菌均匀分布在细胞表面，包括细胞核上方的区域。然而，除非通过短暂将培养物转移到 37°C 来上调毒力因子的产生，否则运动细菌的不均匀分布并不会增强对 HEp-2 细胞的入侵。在 22°C 下过夜生长的运动李斯特菌，然后转移到 37°C 培养 2 小时，与在 37°C 下过夜生长的非运动细菌相比，表达侵袭因子的水平相同，并且侵袭人细胞的效率提高了五倍。总之，研究结果表明：（i）NSS 运动性及其对应于细胞表面的外围位置不依赖于李斯特菌的毒力特征；（ii）在从环境温度过渡到人体温度后的几个小时内，运动性提高了李斯特菌对人 HEp-2 细胞的侵袭能力。
