Effects of aspirin & simvastatin and aspirin, simvastatin, & lipoic acid on heme oxygenase-1 in healthy human subjects

Background: Heme oxygenase 1 (HO-1) degrades heme and protects against oxidative stress. In vitro and animal models suggest that HO-1 is beneficial in several diseases (e.g., postoperative ileus, gastroparesis, acute pancreatitis, and colitis). However, the only drugs (i.e., hemin and heme arginate) which pharmacologically upregulate HO-1 in humans are expensive and can only be administered intravenously. Our aims were to compare the effects of placebo, aspirin, and simvastatin alone, and with α-lipoic acid, on HO-1 protein concentration and activity in humans. Methods: This randomized, double-blind, placebo-controlled study compared the effects of three oral regimens administered for 7 days, i.e., placebo; aspirin (325 mg twice daily) and simvastatin (40 mg twice daily); aspirin, simvastatin, and the sodium salt of R- α-lipoic acid (NaRLA, 600 mg three times daily) on markers of HO-1 activation (i.e., plasma HO-1 protein concentration and venous monocyte HO-1 protein activity) in 18 healthy subjects (14 females). Markers of HO-1 activation were evaluated at baseline, days 2, and 7. Key Results: Baseline HO-1 protein concentrations and activity were similar among the three groups. Compared to placebo, aspirin and simvastatin combined, or together with NaRLA did not affect HO-1 protein concentration or activity at 2 or 7 days. HO-1 protein concentrations and activity were correlated on day 7 (r = 0.75, p = 0.0004) but not at baseline and on day 2. Conclusions & Inferences: At therapeutic doses, aspirin, simvastatin, and α-lipoic acid do not increase plasma HO-1 protein concentration or venous monocyte HO-1 activity in healthy humans.