EFFECTS OF INTRAVENOUS OMEGA-3 AND OMEGA-6 FAT EMULSION ON CYTOKINE PRODUCTION AND DELAYED-TYPE HYPERSENSITIVITY IN BURNED RATS RECEIVING TOTAL PARENTERAL-NUTRITION

Background: The effects of fat emulsions containing omega-3 and omega- 6 polyunsaturated fatty acids (PUFAs) on fatty acid profile, cytokine production, and delayed type hypersensitivity (DTH) in burned rats rec eiving total parenteral nutrition (TPN) were investigated. Methods: A fat emulsion containing only eicosapentaenoic acid (EPA) and docosahex aenoic acid (DHA) was prepared (omega-3 fat emulsion). Sprague-Dawley rats were fed fat-free chow for 2 weeks and were divided into three gr oups according to the contents of TPN. Groups C (n = 11) and C' (n = 1 4) received fat-free TPN. Group omega 6 received safflower oil emulsio n containing linoleic acid (omega-6 PUFA) (n = 11). Group omega 3 (n = 11) received safflower oil emulsion (19% of total caloric intake) and fat emulsion containing only EPA and DHA (1% of total calories). On d ay 5, all rats except for those in group C' were subjected to a 20% fu ll-thickness burn. Group C' did not receive burns. After 48 hours, the rats were killed. Results: The interleukin (IL)-8 concentration was s ignificantly 45% lower in group omega 3 than in group C (p <.05). The IL-10 concentration was significantly 15% lower in group omega 3 than in group omega 6 (p <.05). The IL-6 concentration was increased in gro up omega 6 but not in group omega 3 when compared with group C. The IL -6 and IL-8 were not detected in group C'. Prostaglandin E-2 (PGE(2)) and thromboxane B-2 (TXB2) concentrations were increased by burn injur y, but there were no significant differences among the burned groups. Cell-mediated immunity was thus significantly decreased in burned grou ps (groups C, omega 6, and omega 3; p <.01). However, the decrease of DTH was smaller in group omega 3 and significantly greater when compar ed with groups C and omega 6 (p <.05). Conclusions: omega-6 PUFAs incr eased serum inflammatory cytokine levels in a stressed state. omega-3 fat emulsion reduced IL-8 and IL-10 levels and prevented immunosuppres sion in burned rats that were receiving TPN.