ADHERENCE OF BORRELIA-BURGDORFERI TO THE PROTEOGLYCAN DECORIN

Lyme disease is a tick-borne infection that can develop into a chronic , multisystemic disorder. The causative agent, Borrelia burgdorferi, i s initially deposited by the tick into the host dermis, where it assoc iates with collagen fibers, replicates, and eventually disseminates to other tissues. We have examined the adherence of the spirochete to di fferent components of the collagen fiber and demonstrated that decorin , a proteoglycan which decorates collagen fibers, can support the atta chment of B. burgdorferi. No significant direct attachment to isolated type I or III collagens could be detected. Attachment of the spiroche tes to decorin was highly specific, and the process could be inhibited by soluble decorin but not by various unlabeled, unrelated components . B. burgdorferi also bound soluble I-125-labeled decorin in a time- a nd concentration-dependent manner. Spirochete binding of soluble I-125 -labeled decorin required intact proteoglycan and could not be inhibit ed by either isolated core protein or glycosaminoglycan chain. B. burg dorferi expresses two decorin-binding proteins with apparent molecular masses of 19 and 20 kDa as revealed in a Western blot (immunoblot)-ty pe assay. Our results indicate that decorin may mediate the adherence of B. burgdorferi to collagen fibers in skin and other tissues.