Alterations of brain eicosanoid synthetic pathway in multiple sclerosis and in animal models of demyelination: Role of cyclooxygenase-2

Inflammation is a physiological response to exogenous and endogenous stimuli and, together with demyelination and immune system activation, is one of the key features of multiple sclerosis (MS). Arachidonic acid (AA) metabolism by cyclooxygenase (COX) and lipoxygenase (LO) enzymes leads to the production of proinflammatory eicosanoids, and stimulates cytokine production and activation of microglia and astrocytes, thereby contributing to MS pathology. Current therapies target the immune system but do not specifically target AA-related inflammatory pathway. Corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) are frequently associated with immunomodulatory therapies to treat flu-like adverse effects. Few clinical and mounting preclinical data in MS show that AA metabolism contributes to immune system activation, demyelination and motor disabilities, and administration of NSAIDs reduces these symptoms. The beneficial effect of NSAIDs seems to be a prerogative of COX-2 selective inhibitors and suggests that NSAIDs selective for COX-2 may be more effective than mixed COX-1/2 inhibitors.