Prevention of Bleomycin-Induced Lung Fibrosis in Mice by a Novel Approach of Parallel Inhibition of Cyclooxygenase and Nitric-Oxide Donation Using NCX 466, a Prototype Cyclooxygenase Inhibitor and Nitric-Oxide Donor

Cyclooxygenase (COX)-inhibiting nitric oxide (NO) donors (CINODs) are designed to inhibit COX-1 and COX-2 while releasing NO. COX inhibition is responsible for anti-inflammatory and pain-relieving effects, whereas NO donation can improve microcircula-tion and exert anti-inflammatory and antioxidant actions. In an in vivo mouse model of bleomycin-induced lung fibrosis, we evalu-ated whether a prototype CINOD compound, (S)-(5S)-5,6-bis(nitrooxy)hexyl)2-(6-methoxynaphthalen-2-yl)propanoate (NCX 466), may show an advantage over naproxen, its congener drug not releasing NO. Bleomycin (0.05 IU) was instilled intratracheally to C57BL/6mice, which were then treated orally with vehicle, NCX 466 (1.9 or 19 mg/kg), or an equimolar dose of naproxen (1 or 10 mg/kg) once daily for 14 days. Afterward, airway resistance, as-sumed as lung stiffness index, was assayed, and lung specimens were collected for analysis of lung inflammation and fibrosis. NCX 466 and naproxen dose-dependently prevented bleomycin-induced airway stiffness and collagen accumulation. NCX 466, at the highest dose, was significantly more effective than naproxen in reducing the levels of the profibrotic cytokine transforming growth factor- and the oxidative stress markers thiobarbituric acid reac-tive substance and 8-hydroxy-2-deoxyguanosine. NCX 466 also decreased myeloperoxidase activity, a leukocyte recruitment in-dex, to a greater extent than naproxen. A similar inhibition of prostaglandin E2 was achieved by both compounds. In conclu-sion, NCX 466 has shown a significantly higher efficacy than naproxen in reducing lung inflammation and preventing collagen accumulation. These findings suggest that COX inhibition along with NO donation may possess a therapeutic potential in lung inflammatory diseases with fibrotic outcome