Abstract

Carbon monoxide (CO) mediates many of the biological effects that are attributed to heme oxygenase (HO), the enzyme responsible for CO production in mammals. Antioxidant and anti-inflammatory activities of HO-1, the inducible isoform of heme oxygenase, have been demonstrated in a variety of disease models and a therapeutic exploitation of this pathway is currently under scrutiny. In this context, the liberation of CO from CO-releasing molecules (CO-RMs) is extremely attractive as these compounds may form the basis of a new class of pharmaceuticals. Recent investigations indicate that HO-1 and CO modulate important processes in chronic inflammation; these include the control of immune responses, the production of inflammatory mediators and the mitigation of cartilage or bone destruction. As HO-1 is highly expressed in the joint tissues of patients affected by arthritic diseases, it is plausible to suggest that this pathway may play a protective role against joint degenerative diseases. Studies aimed at identifying the signaling pathways responsive to endogenous CO and CO-RMs in rheumatoid arthritis and other inflammatory states are currently in progress. This research will help to elucidate the molecular mechanisms underlying the pharmacological effects of CO-RMs and may lead to the development of novel therapeutic strategies for the treatment of acute and chronic inflammatory conditions.