Alterations of polyunsaturated fatty acids metabolic pathways in AAD. The classification, formation of polyunsaturated fatty acids and their function in AAD. Decreased concentrations of AA, EPA and DHA lead to the occurrence of proinflammatory events in AAD. Abbreviations: AA, arachidonic acid; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; ECs, endothelial cells; Treg, regulatory T cells; GLA, gamma linolenic acid; DGLA, dihomo gamma linolenic acid; PGs, prostaglandins; COX, cyclooxygenase; LPS, lipopolysaccharide; MMP2, matrix metalloproteinase 2; MMP9, matrix metalloproteinase 9; VCAM-1, vascular cell adhesion molecule 1; ICAM-1, intercellular adhesion factor 1; MCP-1, monocyte chemoattractant protein 1.