HYALURONAN, A POSSIBLE LIGAND MEDIATING TREPONEMA-DENTICOLA BINDING TO PERIODONTAL TISSUE

Binding of Treponema denticola ATCC 35405 to glycosaminoglycans, fibri nogen, type I collagen and porcine periodontal ligament epithelial cel ls was studied using an enzyme-linked immunosorbent assay. T. denticol a bound to hyaluronan (hyaluronic acid) and its hexameric fragments, w hereas little or no binding was detected to chondroitin-4-sulfate or d ermatan sulfate proteoglycan. Binding of T. denticola to hyaluronan gr adually increased during the 2-h incubation time. In contrast, binding to fibrinogen and type I collagen was more rapid, peaking within 5 mi n. T. denticola also bound to microbeads coated with hyaluronan and fo rmed visible aggregates in solution. Pretreatment of the bacteria with hyaluronan or fibrinogen inhibited binding to hyaluronan. Gelatin, bo vine serum albumin, chondroitin-4-sulfate, chondroitin-6-sulfate, hepa rin, dermatan sulfate, glucuronic acid, N-acetylglucosamine and N-acet yl-galactosamine did not inhibit binding. Binding was also inhibited b y heating T. denticola and by pretreatment of the spirochetes with sod ium periodate, phenylmethylsulfonyl fluoride, and p-chloromercurybenzo ic acid. All these treatments also inhibited the chymotrypsinlike acti vity of T. denticola. Hyaluronan strongly inhibited binding of T. dent icola to epithelial cells, whereas the other glycosaminoglycans and N- acetyl-glucosamine did not. The results show that T. denticola binds t o hyaluronan, possibly by a mechanism involving the chymotrypsin-like surface protein of T. denticola.