Involvement of lipopolysaccharide binding protein, CD14, and Toll-like receptors in the initiation of innate immune responses by Treponema glycolipids.
Culture supernatants from Treponema maltophilum associated with periodontitis in humans and Treponema brennaborense found in a bovine cattle disease accompanied with cachexia caused a dose-dependent TNF-alpha synthesis in human monocytes increasing with culture time. This activity could be reduced significantly by blocking the CD14-part of the LPS receptor using the My 4 mAb and by polymyxin B. In the murine macrophage cell line RAW 264.7, Treponema culture supernatants induced TNF-alpha secretion in a LPS binding protein (LBP)-dependent fashion. To enrich for active compounds, supernatants were extracted with butanol, while whole cells were extracted using a phenol/water method resulting in recovery of material exhibiting a similar activity profile. An LPS- LBP binding competition assay revealed an interaction of the treponeme phenol/water extracts with LBP, while precipitation studies implied an affinity to polymyxin B and endotoxin neutralizing protein. Macrophages obtained from C3H/HeJ mice carrying a Toll-like receptor (TLR)-4 mutation were stimulated with treponeme extracts for NO release to assess the role of TLRs in cell activation. Furthermore, NF-kappaB translocation in TLR-2-negative Chinese hamster ovary (CHO) cells was studied. We found that phenol/water-extracts of the two strains use TLRs differently with T. brennaborense-stimulating cells in a TLR-4-dependent fashion, while T. maltophilum-mediated activation apparently involved TLR-2. These results indicate the presence of a novel class of glycolipids in Treponema initiating inflammatory responses involving LBP, CD14, and TLRs.[1]References
- Involvement of lipopolysaccharide binding protein, CD14, and Toll-like receptors in the initiation of innate immune responses by Treponema glycolipids. Schröder, N.W., Opitz, B., Lamping, N., Michelsen, K.S., Zähringer, U., Göbel, U.B., Schumann, R.R. J. Immunol. (2000) [Pubmed]
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