Chi Bo, Qi Mingshan, Kuramitsu Howard K
Department of Oral Biology, State University of New York at Buffalo, 3435 Main Street, Buffalo, NY 14214, USA.
Res Microbiol. 2003 Nov;154(9):637-43. doi: 10.1016/j.resmic.2003.08.001.
Treponema denticola is an oral anaerobic spirochete implicated in periodontal diseases. The chymotrypsin-like protease, dentilisin (PrtP), has been suggested to be an important virulence factor of T. denticola. In this study, we examined the role of dentilisin in T. denticola epithelial monolayer penetration by comparing the wild type and prtP mutant. Wild-type T. denticola can disrupt transepithelial resistance (TER) and substantially penetrate the HEp-2 cell layer. The prtP mutant altered the monolayer only slightly and penetrated the Hep-2 layer in very low numbers. The membrane fraction of wild-type T. denticola is able to complement the prtP mutant in monolayer penetration, while the comparable fraction from the mutant has no such effect. Immunofluorescence studies suggested that wild-type T. denticola altered the TER by likely degrading the tight junctional proteins such as ZO-1. Cytotoxicity was not a major factor in the disruption of TER. The outer membrane vesicles (OMVs) of wild-type T. denticola also disrupted epithelial barrier function and penetrated the epithelial layers. Taken together, these results suggest that T. denticola penetrates the epithelial cell monolayers by altering cellular tight junctions.
齿垢密螺旋体是一种与牙周疾病有关的口腔厌氧螺旋体。类胰凝乳蛋白酶样蛋白酶齿垢素（PrtP）被认为是齿垢密螺旋体的一种重要毒力因子。在本研究中，我们通过比较野生型和prtP突变体，研究了齿垢素在齿垢密螺旋体穿透上皮单层细胞中的作用。野生型齿垢密螺旋体可破坏跨上皮电阻（TER）并大量穿透HEp-2细胞层。prtP突变体对单层细胞的改变很小，且仅有极少量细胞穿透Hep-2层。野生型齿垢密螺旋体的膜组分能够在单层穿透方面补充prtP突变体，而突变体的相应组分则没有这种作用。免疫荧光研究表明，野生型齿垢密螺旋体可能通过降解紧密连接蛋白如ZO-1来改变TER。细胞毒性不是TER破坏的主要因素。野生型齿垢密螺旋体的外膜囊泡（OMV）也破坏上皮屏障功能并穿透上皮层。综上所述，这些结果表明齿垢密螺旋体通过改变细胞紧密连接来穿透上皮细胞单层。
