Inflammatory mediators are inhibited by a taurine metabolite in CpG oligodeoxynucleotide and IFN-r activated macrophage cell line.

Taurine plays an important role in brain and retinal development, and has an antiinflammatory and antioxidant function. Taurine chloramine (Tau-Cl) is produced in polymorphonuclear leukocytes via the myeloperoxidase/halide system. We previously demonstrated that Tau-Cl inhibits the production of nitric oxide (NO) and TNF-alpha in human and murine macrophages activated with IFN-gamma in combination with individual Toll-like receptor (TLR) ligands including those for TLR2 and/or TLR4. In the current study, we further explored the effects of Tau-Cl in RAW 264.7 cells stimulated with the TLR9 ligand CpG oligodeoxynucleotide (ODN). Specifically, we examined the effect of CpG ODN plus IFN-gamma on the production of NO and TNF-alpha, and the effect of Tau-Cl on this process. Our findings show that CpG ODN plus IFN-gamma-activated RAW 264.7 cells secrete high levels of NO and TNF-alpha, and that Tau-Cl (0.8 mM) inhibits this effect in a dose-dependent manner, more potently inhibiting the production of NO (99% inhibition) than that of TNF-alpha (48% inhibition). Nitric oxide synthase (iNOS) protein was also induced by CpG ODN plus IFN-gamma, and was also inhibited by Tau-Cl. Furthermore, while CpG ODN plus IFN-gamma induced TNF-alpha and iNOS mRNAs, Tau-Cl transiently suppressed this effect. Taurine itself had no effects on any of these processes. Our findings in a macrophage cell line demonstrate that Tau-Cl inhibits proinflammatory mediators resulting from TLR9 activation, and have implications for the utility of Tau-Cl in scenarios where such activation is deleterious such as in autoimmune conditions or infections in which overwhelming inflammation may occur. CpG ODNs and Tau-Cl both have potential for topical treatment of autoimmune conditions, including psoriasis, vitiligo, and alopecia areata. As CpG ODNs may, under some conditions, up-regulate Tregs, addition of Tau-Cl to CpG ODN topical formulations has potential for improving cancer immunotherapy.