Heme Oxygenase 1 in Regulation of Inflammation and Oxidative Damage

Heine oxygenase-1 (HO-1) and HO-2 are cytoprotective enzymes that degrade heme (a potent oxidant) to generate carbon monoxide (CO, a vasodilatory gas that has anti-inflammatory properties), bilirubin (an antioxidant derived from biliverdin), and iron (sequestered by ferritin). This chapter focuses on HO-1, the inducible isoform that is upregulated by oxidative stress. Because of properties of HO-1 and its products, it is believed that HO-1 may play an important role in protecting cells and tissues in the settings of increased oxidative stress. The chapter uses several in vivo models that induce oxidative stress in animals to study the role of HO-1 in response to pathophysiological stress. HO-1 expression level, inflammatory cell infiltration, and oxidative damage are assessed in tissues of interest.