The major outer sheath protein(Mosp), which consists of glucose, galactose, glutamine, galactosamine, and fucose, is the most abundant outer membrane protein on the cell surface of Treponema denticola(T.denticola) at low molecular polymer form. The central domain of Mosp plays a significant role in the adhesion of bacteria and the host proteins. Mosp also acts as an adhesion to some extent, thereby competitively inhibiting the combination of T.denticola, Porphyromonas gingivalis, and Fusobacterium nucleatum. Cytotoxicity is another contributing factor that allows the bacteria to obtain nutrients, transport bacterial products to the infected host cells, and mediate cytotoxic activity. Furthermore, the Mosp can destroy the migration of fibroblasts and neutrophils. However, the migration of fibroblasts is closely related to reconstruction and healing in periodontal connective tissues, whereas neutrophils play key roles in the periodontal innate immune system, thereby enabling neutrophils to limit the spread of pathogens. Understanding the mechanism underlying Mosp activity may provide new insights intothe reduction of T.denticola pathogenicity and may lay a solid theoretical foundation fordelaying the progression of periodontitis.
