THE SURFACE PROTEINASE OF TREPONEMA-DENTICOLA MAY MEDIATE ATTACHMENT OF THE BACTERIA TO EPITHELIAL-CELLS

Attachment of Treponema denticola ATCC 35405 was studied using a new e pithelial model consisting of cultured periodontal ligament epithelial cells. T. denticola bound rapidly but selectively to the epithelial c ells. Even at a high concentration of 1 x 10(11) bacteria/mL, 31% of t he epithelial cells did not bind any treponemes in confluent cultures. However, some of the cells bound large numbers of spirochetes. In spa rse cultures with migrating epithelial cells, higher amounts of T. den ticola were bound than in confluent cultures. Electron microscopy show ed direct contact of T. denticola and epithelial cell membranes withou t apparent preference in the adhesion sites in either of the cell type s. Fibronectin and bovine serum albumin did not inhibit binding of T. denticola to the epithelial cells. In contrast, serum and fibrinogen m arkedly inhibited binding. Pretreatment of T., denticola with proteina se K, heating at 60 degrees C or exposure to pH 3.2 inhibited the atta chment by 30, 78 and 89%, respectively, suggesting that T. denticola p roteins were involved in the attachment. Protease inhibitors, phenylme thylsulfonyl fluoride and p-chloromercuribenzoic acid that inhibited t he chymotrypsinlike proteinase of T. denticola, also inhibited the att achment of the spirochetes to the epithelial cells. Purified chymotryp sin-like proteinase bound rapidly to the epithelial cells and specific antibodies against the proteinase inhibited attachment of the trepone mes to the epithelial cells. The results suggest that the T. denticola surface-bound chymotrypsin-like proteinase is involved in the binding of the bacteria to epithelial cells. (C) 1996 Academic Press