m-40403 and Pleurisy

The nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays a pivotal role in the induction of genes involved in physiological processes, as well as in the response to inflammation. In this study, we used a selective nonpeptidyl superoxide dismutase mimetic, M40403, to investigate the role of superoxide anion in NF-kappaB activation during acute inflammation in mice. Injection of carrageenan into the pleural cavity of mice induced an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained a large number of neutrophils, as well as an increased production of tumor necrosis factor-alpha and interleukin-1beta. All parameters of inflammation were attenuated by M40403 (10 mg/kg i. p., 30 min prior to carrageenan administration). These inflammatory events were associated with the activation of NF-kappaB in the lung. In particular, the appearance of inhibitory protein kappaB-alpha (IkappaB-alpha) in homogenates of lung tissues was investigated by immunoblot analysis at 4 h after carrageenan administration. IkappaB-alpha levels were substantially reduced in the lung tissue from carrageenan-treated mice in comparison with sham-treated mice. Furthermore, to detect NF-kappaB/DNA binding activity, whole extracts from lung tissue of each mouse were analyzed by electrophoretic mobility-shift assay. The DNA binding activity significantly increased in whole extracts obtained from lung tissues of vehicle-treated mice 4 h after carrageenan administration. Treatment of mice with M40403 caused a significant inhibition of carrageenan-induced IkappaB-alpha degradation and NF-kappaB/DNA binding activity. These data confirm that M40403 exerts a potent antiinflammatory activity and clearly demonstrate that the reduction of the inflammatory process is associated with modification of the activation of signal transduction pathways.

Topics: Animals; Carrageenan; I-kappa B Proteins; Inflammation; Interleukin-1; Lung; Male; Manganese; Mice; NF-kappa B; NF-KappaB Inhibitor alpha; Organometallic Compounds; Pleurisy; Random Allocation; Signal Transduction; Superoxide Dismutase; Superoxides; Tumor Necrosis Factor-alpha

1. M40403 is a low molecular weight, synthetic manganese containing superoxide dismutase mimetic (SODm) that removes superoxide anions (*O2-) without interfering with other reactive species known to be involved in inflammatory responses (e.g. nitric oxide, NO and peroxynitrite, ONOO-). 2. As such, M40403 represents an important pharmacological tool to dissect the roles of *O2- in acute and chronic inflammation. For this purpose, the pharmacological profile of M40403 was evaluated in carrageenan-induced pleurisy. 3. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by: fluid accumulation in the pleural cavity which contained a large number of neutrophils (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NOx), prostaglandin E2 (PGE2), tumour necrosis factor alpha, (TNFalpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and interleukin-10 (IL-10). 4. All parameters of inflammation were attenuated by M40403 except for NOx, PGE2 and IL-10 which remained unaltered. Furthermore, carrageenan induced an upregulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. 5. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine and PARS was reduced by M40403. 6. These results clearly indicate that *O2- plays a critical role in the development of the inflammatory response by altering key components of the inflammatory cascade. Therefore, synthetic enzymes of SOD such as M40403, offers a novel therapeutic approach for the management of various inflammatory diseases where these radicals have been postulated to play a role.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cytokines; Dinoprostone; DNA Damage; Intercellular Adhesion Molecule-1; Macrophages; Male; Manganese; Nitrates; Organometallic Compounds; P-Selectin; Pleurisy; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Sprague-Dawley; Superoxides