Chapter 14 - Marine n-3 polyunsaturated fatty acids and inflammatory diseases

Abstract

Inflammation is an essential component of the host defense system, but uncontrolled chronic low-grade inflammation is believed to play a central role in many chronic pathologies including auto-immune diseases (e.g., rheumatoid arthritis), inflammatory bowel diseases (e.g., ulcerative colitis and Crohn's disease), and neurodegenerative diseases (e.g., Alzheimer's disease). Dietary essential fatty acids are precursors of inflammatory mediators, with n-6 and marine n-3 polyunsaturated fatty acids (PUFAs) possessing pro-inflammatory and antiinflammatory properties, respectively. Marine n-3 PUFAs (e.g., DHA and EPA), especially EPA, competitively inhibit the production of prostaglandins and leukotrienes from AA by competing for the same enzymatic pathway and also act as precursors of less potent pro-inflammatory mediators. Additionally, antiinflammatory activity of marine n-3 PUFAs includes reduction in the production of cytokines such as IL-1β, IL-6 and TNF-α, reduction in the expression of adhesion molecules on immune cells, reduction in T-cell proliferation and resolving inflammation through metabolites acting as specialized pro-resolving mediators. Therefore, marine n-3 PUFAs are believed to be potentially therapeutic candidates targeting resolution of inflammation for preventing and treating a variety of chronic inflammatory diseases, including rheumatoid arthritis, inflammatory bowel diseases, and Alzheimer's disease. Although in vitro and animal experiments consistently demonstrated promising effects of marine n-3 PUFAs on inflammation resolution and alleviation of inflammation related diseases, clinical trials of n-3 PUFAs in inflammatory bowel diseases and Alzheimer's disease did not provide enough robust evidence yet to support the therapeutic use of marine n-3 PUFAs.