Allison C, Coleman N, Jones P L, Hughes C
Department of Pathology, Cambridge University, United Kingdom.
Infect Immun. 1992 Nov;60(11):4740-6. doi: 10.1128/iai.60.11.4740-4746.1992.
Proteus mirabilis causes serious kidney infections which can involve invasion of host urothelial cells. We present data showing that the ability to invade host urothelial cells is closely coupled to swarming, a form of cyclical multicellular behavior in which vegetative bacteria differentiate into hyperflagellated, filamentous swarm cells capable of coordinated and rapid population migration. Entry into the human urothelial cell line EJ/28 by P. mirabilis U6450 isolated at different stages throughout the swarming cycle was measured by the antibiotic protection assay method and confirmed by electron microscopy. Differentiated filaments entered urothelial cells within 30 min and were 15-fold more invasive (ca. 0.18% entry in 2 h) than an equivalent dry weight of vegetative cells isolated before differentiation, which attained only ca. 0.012% entry in the 2-h assay. The invasive ability of P. mirabilis was modulated in parallel with flagellin levels throughout two cycles of swarming. Septation and division of intracellular swarm cells produced between 50 and 300 vegetative bacteria per human cell, compared with 4 to 12 intracellular bacteria after incubation with vegetative cells. Transposon (Tn5) mutants of P. mirabilis with specific defects in motility and multicellular behavior were compared with the wild-type for the ability to invade. Mutants which lacked flagella (nonmotile nonswarming) were entirely noninvasive, and those which were motile but defective in swarm cell formation (motile nonswarming) were 25-fold less invasive than wild-type vegetative cells. Mutants with defects in the coordination of multicellular migration and the temporal control of consolidation (cyclical reversion of swarm cells to vegetative cells) were reduced ca. 3- to 12-fold in the ability to enter urothelial cells. In contrast, a nonhemolytic transposon mutant which swarmed normally retained over 80% of wild-type invasive ability. Swarm cells and early consolidation cells were at least 10-fold more cytolytic than vegetative cells as a result of their high-level production of hemolysin.
奇异变形杆菌可引发严重的肾脏感染，这种感染可能涉及宿主尿路上皮细胞的侵袭。我们提供的数据表明，侵袭宿主尿路上皮细胞的能力与群体游动密切相关，群体游动是一种周期性多细胞行为，在此过程中，营养态细菌分化为具有高度鞭毛的丝状群体细胞，能够进行协调且快速的群体迁移。通过抗生素保护测定法测量了在群体游动周期不同阶段分离得到的奇异变形杆菌U6450进入人尿路上皮细胞系EJ/28的情况，并通过电子显微镜进行了证实。分化后的丝状体在30分钟内进入尿路上皮细胞，其侵袭性比分化前分离得到的同等干重的营养态细胞高15倍（在2小时内约0.18%的细胞进入），而后者在2小时的测定中仅约0.012%的细胞进入。在两个群体游动周期中，奇异变形杆菌的侵袭能力与鞭毛蛋白水平平行调节。与营养态细胞孵育后，细胞内群体细胞的分隔和分裂在每个人类细胞中产生50至300个营养态细菌，而与营养态细胞孵育后每个细胞内有4至12个细菌。将在运动性和多细胞行为方面存在特定缺陷的奇异变形杆菌转座子（Tn5）突变体与野生型进行侵袭能力比较。缺乏鞭毛的突变体（无运动性不群体游动）完全没有侵袭性，而那些有运动性但在群体细胞形成方面有缺陷的突变体（有运动性不群体游动）的侵袭性比野生型营养态细胞低25倍。在多细胞迁移协调和巩固的时间控制（群体细胞周期性恢复为营养态细胞）方面存在缺陷的突变体进入尿路上皮细胞的能力降低了约3至12倍。相比之下，正常群体游动的非溶血转座子突变体保留了超过80%的野生型侵袭能力。由于群体细胞和早期巩固细胞高水平产生溶血素，它们的细胞溶解性至少比营养态细胞高10倍。
