Effects of intravenous ω-3 and ω-6 fat emulsion on cytokine production and delayed type hypersensitivity in burned rats receiving total parenteral nutrition

Background: The effects of fat emulsions containing ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) on fatty acid profile, cytokine production, and delayed type hypersensitivity (DTH) in burned rats receiving total parenteral nutrition (TPN) were investigated. Methods: A fat emulsion containing only eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was prepared (ω-3 fat emulsion). Sprague-Dawley rats were fed fat-free chow for 2 weeks and were divided into three groups according to the contents of TPN. Groups C (n = 11) and C' (n = 14) received fat-free TPN. Group ω6 received safflower oil emulsion containing linoleic acid (ω-6 PUFA) (n = 11). Group ω3 (n = 11) received safflower oil emulsion (19% of total caloric intake) and fat emulsion containing only EPA and DHA (1% of total calories). On day 5, all rats except for those in group C' were subjected to a 20% full-thickness burn. Group C' did not receive burns. After 48 hours, the rats were killed. Results: The interleukin (IL)-8 concentration was significantly 45% lower in group ω3 than in group C (p <.05). The IL-10 concentration was significantly 15% lower in group ω3 than in group ω6 (p <.05). The IL-6 concentration was increased in group ω6 but not in group ω3 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 (TXB 2 ) concentrations were increased by burn injury, but there were no significant differences among the burned groups. Cell-mediated immunity was thus significantly decreased in burned groups (groups C, ω6, and ω3; p < .01). However, the decrease of DTH was smaller in group ω3 and significantly greater when compared with groups C and ω6 (p <.05). Conclusions: ω-6 PUFAs increased serum inflammatory cytokine levels in a stressed state. ω-3 fat emulsion reduced IL-8 and IL-10 levels and prevented immunosuppression in burned rats that were receiving TPN.