Dietary Platycladus orientalis seed oil suppresses anti-erythrocyte autoantibodies and prolongs survival of NZB mice.

Dietary fish oils rich in 20:5(5,8,11,14,17) and 22:6(4,7,10,13,16,19) are known to replace arachidonic acid [20:4(5,8,11,14)] and to improve the immunopathology of New Zealand mice. However, in humans, similar dietary strategies may be impractical because of the high levels of fish oils required. In contrast, we believe that beneficial effects in humans may be attainable using new exotic fatty acids. Toward this end, we have focused on 5,11,14-eicosatrienoic acid [5,11,14-ETA, 20:3(5,11,14)]. This fatty acid is structurally analogous to 20:4(5,8,11,14) but lacks the delta-8 double bond essential for conversion to eicosanoids. To examine our hypothesis, diets containing the oil of Platycladus orientalis containing 3% 5,11,14-ETA, a matched control oil, fish oil, or safflower oil were fed to NZB mice. There was a dramatic delay in both the onset and the titer of direct Coombs' tests in mice fed P. orientalis oil. These were directly reflected by the abundance of 5,11,14-ETA in serum lipids. Most striking was the accumulation of 5,11,14-ETA in serum and tissue phospholipids. Though constituting only 3% of dietary fatty acids, 5,11,14-ETA was the most abundant long chain polyunsaturated fatty acid in the serum phospholipids, suggesting that it very successfully competed with 20:4 as a constituent of membrane lipids. 5,11,14-ETA was incorporated into all tissue phospholipids examined except brain phosphatidyl inositol. Among tissues, liver showed the highest incorporation of 5,11,14-ETA into phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI), yet spleen PE had a higher quantity of ETA than other tissues. Lesser arachidonate in spleen PS, heart PC, and heart PI showed the evidence of replacement by 5,11,14-ETA. The data presented illustrates how new nutrition can modify autoimmune responses and emphasizes the need for further studies based on new nutritional strategies.