Supplementation of diet with krill oil protects against experimental rheumatoid arthritis

<p>Abstract</p> <p>Background</p> <p>Although the efficacy of standard fish oil has been the subject of research in arthritis, the effect of krill oil in this disease has yet to be investigated. The objective of the present study was to evaluate a standardised preparation of krill oil and fish oil in an animal model for arthritis.</p> <p>Methods</p> <p>Collagen-induced arthritis susceptible DBA/1 mice were provided <it>ad libitum </it>access to a control diet or diets supplemented with either krill oil or fish oil throughout the study. There were 14 mice in each of the 3 treatment groups. The level of EPA + DHA was 0.44 g/100 g in the krill oil diet and 0.47 g/100 g in the fish oil diet. Severity of arthritis was determined using a clinical scoring system. Arthritis joints were analysed by histopathology and graded. Serum samples were obtained at the end of the study and the levels of IL-1α, IL-1β, IL-7, IL-10, IL-12p70, IL-13, IL-15, IL-17 and TGF-β were determined by a Luminex™ assay system.</p> <p>Results</p> <p>Consumption of krill oil and supplemented diet significantly reduced the arthritis scores and hind paw swelling when compared to a control diet not supplemented with EPA and DHA. However, the arthritis score during the late phase of the study was only significantly reduced after krill oil administration. Furthermore, mice fed the krill oil diet demonstrated lower infiltration of inflammatory cells into the joint and synovial layer hyperplasia, when compared to control. Inclusion of fish oil and krill oil in the diets led to a significant reduction in hyperplasia and total histology score. Krill oil did not modulate the levels of serum cytokines whereas consumption of fish oil increased the levels of IL-1α and IL-13.</p> <p>Conclusions</p> <p>The study suggests that krill oil may be a useful intervention strategy against the clinical and histopathological signs of inflammatory arthritis.</p

N-3 POLY-UNSATURATED FATTY-ACIDS, INTERLEUKIN-1, AND TUMOR NECROSIS FACTOR

We examined whether the synthesis of interleukin-1 or tumor necrosis factor, two cytokines with potent inflammatory activities, is influenced by dietary supplementation with n—3 fatty acids.Nine healthy volunteers added 18 g of fish-oil concentrate per day to their normal Western diet for six weeks. We used a radioimmunoassay to measure interleukin-1 (IL-1β and IL-1α) and tumor necrosis factor produced in vitro by stimulated peripheral-blood mononuclear cells. With endotoxin as a stimulus, the synthesis of IL-1β was suppressed from 7.4±0.9 ng per milliliter at base line to 4.2±0.5 ng per milliliter after six weeks of supplementation (43 percent decrease; P = 0.048). Ten weeks after the end of n-3 supplementation, we observed a further decrease to 2.9±0.5 ng per milliliter (61 percent decrease; P = 0.005). The production of IL-1α and tumor necrosis factor responded in a similar manner. Twenty weeks after the end of supplementation, the production of IL-1βIL-1α, and tumor necrosis factor had returned to the presupplement level. The decreased production of interleukin-1 and tumor necrosis factor was accompanied by a decreased ratio of arachidonic acid to eicosapentaenoic acid in the membrane phospholipids of mononuclear cells.We conclude that the synthesis of IL-1β, IL-1α, and tumor necrosis factor can be suppressed by dietary supplementation with long-chain n—3 fatty acids. The reported antiinflammatory effect of these n—3 fatty acids may be mediated in part by their inhibitory effect on the production of interleukin-1 and tumor necrosis factor