Researchers have previously reported that hybrid New Zealand female mice fed a diet enriched in omega-3 lipid-rich fish oil versus omega-6 lipid-rich corn oil show delayed development of autoimmune lupus nephritis and longer life span. The present study was carried out to explore the possible beneficial effects of oil from Antarctic krill (Euphausia superba) as an alternative source of omega-3 lipids.
Mice were fed a nutritionally adequate semipurified diet supplemented with either 10% krill oil or 10% corn oil. Cross-sectional studies were carried out on kidneys and spleens at 3.5 and 6.5 months of age. Study results indicate that Krill Oil prolonged life span to a greater degree than corn oil (CO, 266.7 days plus or minus 12.5; KO, 330.2 days plus or minus 19.2; P<0.001) and delayed the onset of proteinuria.
Splenocytes from Krill Oil mice displayed greater proliferative responses to mitogen, and significantly lower Pgp-1+ cells in both CD4+ and CD8+ T cell subsets. Lipid extracts of splenocytes from Krill Oil fed mice revealed higher levels of eicosapentaenoic (omega-3 EPA) and docosahexaenoic (omega-3 DHA) acids. EPA suppresses prostaglandin synthesis. Further, Northern blot analysis showed decreased expression of the oncogene c-ras (1.5-fold, P<0.05) in the spleens of Krill Oil fed mice. The expression of transforming growth factor beta1 was higher in spleen cell extracts (3.5-fold; P<0.025), but lower in kidney extracts (5.97- fold; P<0.025) of Krill Oil fed mice.
The data indicate that dietary supplementation with Krill Oil modulates expression of TGFbeta in an organ specific manner. In the spleen, TGFbeta could be immunosuppressive, whereas its expression in the kidney may be pathological and proinflammatory. In summary, dietary Krill Oil, like fish oil, can suppress the development of autoimmune murine lupus, and its effects on inflammatory mediators are organ specific.
Source: Nutrition Research (USA), 1996, 16/3 (489-503).