Pharmacological manipulation of the inflammatory cascade by the superoxide dismutase mimetic, M40403

SOD mimetics are coming of age

The list of pathophysiological conditions that are associated with the overproduction of superoxide anions expands every day. The most exciting realization is that there seems to be a similarity between the tissue injury that is observed in various disease states, as superoxide anions produce tissue injury and associated inflammation in all tissues in similar ways. Tissue injury and inflammation form the basis of many disease pathologies, including ischaemia and reperfusion injuries, radiation injury, hyperoxic lung damage and atherosclerosis. This commonality provides a unique opportunity to manipulate numerous disease states with an agent that removes superoxide anions.

Reactive oxygen species as mediators in asthma

This review describes production and effects of reactive oxygen species (ROS) on airway function. ROS are important in many physiological processes but can also have detrimental effects on airway cells and tissues when produced in high quantities or during the absence of sufficient amounts of anti-oxidants. Therefore, these mediators play a prominent role in the pathogenesis of various inflammatory airway disorders, including asthma. Effects of ROS on airway function in asthma have been studied with isolated airway cells and tissues and with animal models and patients. With the use of inhibitors, transgenic animals and measurements of the release of ROS within the airways, it became clear that oxidative stress contributes to the initiation and worsening of inflammatory respiratory disorders.

Pyrrolidine dithiocarbamate attenuates the development of acute and chronic inflammation

The nuclear factor-kappaB (NF-kappaB) is a transcription factor which plays a pivotal role in the induction of genes involved in physiological processes as well as in the response to injury and inflammation. Dithiocarbamates are antioxidants which are potent inhibitors of NF-kappaB. We postulated that pyrrolidine dithiocarbamate (PDTC) would attenuate inflammation. In the present study we investigate the effects of PDTC in animal models of acute and chronic inflammation (carrageenan-induced pleurisy and collagen-induced arthritis). We report here for the first time that PDTC (given at 100, 30 or 10 mg kg(-1) i.p. in the pleurisy model or at 10 mg kg(-1) i.p. every 48 h in the arthritis model) exerts potent anti-inflammatory effects (e.g. significant reduction of (A) pleural exudate formation, (B) polymorphonuclear cell infiltration, (C) lipid peroxidation, (D) inducible nitric oxide synthase (iNOS) activity and nitric oxide production (E) plasma and pleural exudates levels of interleukin-1beta and tumour necrosis factor-alpha, (F) histological injury and (G) delayed development of clinical indicators). Furthermore, PDTC reduced immunohistochemical evidence of (A) formation of nitrotyrosine, (B) activation of poly (ADP-ribose) polymerase (PARP), (C) expression of iNOS and (D) expression of cyclo-oxygenase-2 (COX-2) in the lungs of carrageenan-treated mice and in the joints from collagen-treated mice. Additionally, Western blotting and immunohistochemical analysis of lung tissue revealed that PDTC prevented degradation of IKB-alpha and translocation of NF-kappaB from the cytoplasm into the nucleus. Taken together, our results clearly demonstrate that prevention of the activation of NF-kappaB by PDTC reduces the development of acute and chronic inflammation. Therefore, inhibition of NF-kappaB may represent a novel approach for the therapy of inflammation.

Protective effects of M40403, a superoxide dismutase mimetic, in a rodent model of colitis

Inflammatory bowel disease is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of M40403, a superoxide dismutase mimetic, in rats subjected to experimental colitis. Colitis was induced in rats by intracolonic instillation of trinitrobenzene sulfonic acid (TNBS). Rats experienced bloody diarrhoea and significant loss of body weight. At 4 days after TNBS administration, the colon damage was characterised by areas of mucosal necrosis. Neutrophil infiltration (indicated by myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1 and expression of P-selectin and high levels of malondialdehyde. Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) synthetase showed an intense staining in the inflamed colon. Treatment with M40403 (5 mg/kg daily i.p.) significantly reduced the appearance of diarrhoea and the loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture as well as a significant reduction of colonic myeloperoxidase activity and malondialdehyde levels. M40403 also reduced the appearance of nitrotyrosine and poly (ADP-ribose) synthetase immunoreactivity in the colon as well as reduced the up-regulation of ICAM-1 and the expression of P-selectin. The results of this study suggested that administration of a superoxide dismutase mimetic may be beneficial for treatment of inflammatory bowel disease.