Virulence Determinants of Oral Treponemes
Richard P. Ellen
from: Pathogenic Treponema: Molecular and Cellular Biology (Edited by: Justin D. Radolf and Sheila A. Lukehart). Caister Academic Press, U.K. (2006)
Abstract
Oral treponemes are indigenous bacteria that become opportunistic pathogens in the mixed microflora that colonizes the space between the teeth and inflamed gingival tissues (periodontal pocket). The extensively studied Treponema denticola binds to and degrades extracellular matrix and thereby probably contributes to the disruption of the gingival epithelial barrier and bacterial penetration of the underlying connective tissue. Well-conserved motility and chemotactic properties also promote local tissue invasion. The major outer sheath protein (Msp) of T. denticola is differentially toxic to a variety of host cells. It also perturbs cytoskeletal and calcium dynamics in host cells that retain viability (e.g. fibroblasts). The generation of volatile sulphur containing compounds from amino acid metabolism by the enzyme cystalysin is also cytotoxic. Some lipoproteins and outer sheath glycolipids trigger proinflammatory pathways of tissue damage. T. denticola may degrade chemokines of innate immunity pathways and activate host matrix metalloproteinases; yet, it is relatively resistant to b-defensins. Since 80% of the phylotypes of oral treponemes have yet to be cultivated in vitro, their potential pathogenicity has probably been underestimated read more ...
