[Anti-inflammatory pro-resolving derivatives of omega-3 and omega-6 polyunsaturated fatty acids]

Inflammation is a physiological defense reaction of living tissues to injury or infection. An array of mediators, including those derived from omega-6 (omega6) polyunsaturated fatty acids (PUFAs), such as arachidonic acid (AA) e.g. prostaglandins and leukotrienes, promote the inflammatory response. Acute inflammation has several programmed fates, including complete resolution or progression to chronic inflammation, scarring, and eventual loss of tissue function. Studies on AA-derived proinflammatory mediators led to the discovery of AA-derived anti-inflammatory and pro-resolving compounds. These include lipoxins, originating from AA, and resolvins, originating from the omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as well as the omega-6 PUFA docosapentaenoic acid (DPA-omega6). DHA is also a substrate for other anti-inflammatory mediators, i.e. neuroprotectin and maresin. Because of their role in the final phase of acute inflammation, i.e. the resolution of inflammation, the above anti-inflammatory mediators were named pro-resolving mediators. They are formed in cooperating cells present in the region of inflammation in a process called transcellular biosynthesis with the aid of specific lipoxygenases (LOX) and cyclooxygenases (COX). Pro-resolving anti-inflammatory mediators exert their biological activities in a receptor-dependent manner in the resolution phase of inflammation. Of their various biological effects, the most important include inhibition of leukocyte mobilization and traffic through endothelial or epithelial layers, suppression of proinflammatory cytokine release by different cells present in inflamed tissue, and stimulation of the phagocytic activity of monocytes/macrophages. This article surveys the current knowledge on inflammation and the role of the pro-resolving and anti-inflammatory potential of lipid-derived agonistic mediators.