P6 Oxidative stress suppresses expression of cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST) in critical limb ischemia (CLI) patients.

Introduction: CBS, CSE and 3-MST are the enzymatic source of endogenous hydrogen sulfide (H2S), a gaseous signaling molecule implicated in a wide range of physiological processes. We investigated the status of CBS, CSE, and 3-MST as well as the extent of oxidative stress in skeletal muscle tissue obtained from patients suffering from critical limb ischemia (CLI) ± diabetes mellitus (Db). Methods/Results: We found that both mRNA and protein levels of CSE, CBS, and 3-MST were significantly decreased in skeletal muscle of CLI (>2 fold, p <0.05) and CLI +Db (2 fold, p <0.05) patients as judged by RT-qPCR and immunoblot, respectively. We also observed reduced expression of nuclear factor-erythriod 2-related factor (Nrf2), a factor responsible for the expression of antioxidant response element-regulated genes (2 fold, p <0.05) and Cu, Zn-super oxide dismutase, an antioxidant enzyme (2 fold, P <0.05) in skeletal muscle of both patients. Biomarkers of oxidative stress, such as malondialdehyde and protein carbonyl formation were significantly increased (2 fold) in skeletal muscle of CLI and CLI +Db patients as compared with age-matched controls. Conclusion: The present study suggests that the induction of oxidative stress in skeletal muscle of both CLI and CLI +Db patients may directly down-regulate the expression of the endogenous H2S-generating enzymes: CSE, CBS, and 3-MST. Increased oxidative stress and reductions in H2S bioavailability may contribute to the pathogenesis of CLI. [Copyright &y& Elsevier]