Fish oil supplementation does not impair the gut immune response to Trichinella spiralis infection in rats

Background: Fish oil has been recommended as a source of omega-3 fatty acid s for preterm infants and for therapy of some inflammatory diseases. Methods: Because fish oil supplementation could downregulate the host's imm une response, we studied the gut inflammatory response to an enteric infect ion in 72 rats assigned to three dietary groups with differing fatty acid p rofile: 1) fish oil, rich in eicosapentaenoic and docosahexaenoic acid; 2) olive oil, containing 71% monounsaturated fat; and 3) rat chow, containing 57% saturated fat. One half (n = 36) of the rats were infected with Trichin ella spiralis larvae; the other half served as controls. The inflammatory r esponse to initial infection (study 1)1 and type I hypersensitivity respons e to a subsequent parasite-derived antigenic challenge (study 2) were asses sed. Jejunal inflammatory cell infiltrate, mean villus height, disaccharida se levels, changes in short-circuit current in response to glucose absorpti on, and chloride secretagogues (study 1) were measured 9 days after infecti on. Short-circuit current changes induced by chloride secretion were measur ed when the proximal jejunum was challenged with T, spiralis-derived antige n 40 days after infection (study 2). Results: In study 1, jejunal tissue from infected animals had more eosinoph ilic infiltrate, lower disaccharidase levels, and less glucose absorptive a nd chloride secretory capacity than tissue from noninfected animals. In stu dy 2, the jejunum of infected animals showed an antigen-induced chloride se cretory response, whereas no response was obtained from jejunal tissue from noninfected animals. Type of diet did not affect the response in either st udy. Conclusion: Under the conditions of this experiment, fish oil supplementati on did not interfere with the local intestinal inflammatory response after T, spiralis infection.