Toll-like receptor-2 mediates Treponema glycolipid and lipoteichoic acid-induced NF-kappa B translocation

Recently Toll-like receptors (TLRs) have been found to be involved in cellu lar activation by microbial products, including lipopolysaccharide, lipopro teins, and peptidoglycan. Although for these ligands the specific transmemb rane signal transducers TLR4, TLR-2, or TLR-2 and 6 have now been identifie d, the molecular basis of recognition of lipoteichoic acids (LTAs) and rela ted glycolipids has not been completely understood. In order to determine t he role of TLRs in immune cell activation by these stimuli, experiments inv olving TLR-2-negative cell lines, TLR-expression plasmids, macrophages from TLR-4-deficient C3H/HeJ-mice, and inhibitory TLR-4/MD-2 antibodies were pe rformed. Glycolipids from Treponema maltophilum and Treponema brennaborense , as well as highly purified LTAs from Staphylococcus aureus and Bacillus s ubtilis exhibited TLR-2 dependence in nuclear factor KB activation and cyto kine induction; however, T. brennaborense additionally appeared to signal v ia TLR-4. Fractionation of the T. brennaborense glycolipids by hydrophobic interaction chromatography and subsequent cell stimulation experiments reve aled two peaks of activity, one exhibiting TLR-2-, and a second TLR-4-depen dence. Furthermore, we show involvement of the signaling molecules MyD88 an d NIK in cell stimulation by LTAs and glycolipids by dominant negative over expression experiments. In summary, the results presented here indicate tha t TLR-2 is the main receptor for Treponema glycolipid and LTA-mediated infl ammatory response.