Taurine haloamines and heme oxygenase-1 cooperate in the regulation of inflammation and attenuation of oxidative stress.

Taurine chloramine (TauCl) and Taurine bromamine (TauBr), products of the neutrophil myeloperoxidase halide system, exert anti-inflammatory properties. They inhibit the production of a variety of inflammatory mediators, such as prostaglandin E2 (PGE2), nitric oxide (NO) and proinflammatory cytokines. Heme oxygenase-1 (HO-1), a stress inducible enzyme, degrades heme to biliverdin, free iron and carbon monoxide (CO), which are involved in the anti-inflammatory and antioxidant actions of HO-1. Recently we have demonstrated that taurine haloamines induce the expression of HO-1 in inflammatory cells. In this study we examined whether HO-1 participates in taurine haloamines-mediated suppression of proinflammatory cytokine production. We have shown that TauCl/TauBr and CO inhibit the production of TNF-alpha, IL-12 and IL-6, in a similar dose-dependent manner. However, the suppressor activity of TauCl was not altered in HO-1 deficient mice. Therefore, HO-1 and TauCl may independently regulate the production of proinflammatory cytokines. We suggest that TauCl and TauBr provide a link between the two antioxidant systems: the cysteine pathway and the heme oxygenase system.