title: Dietary docosahexaenoic acid suppresses inflammation and immunoresponses in contact hypersensitivity reaction in mice.
abstract: This study was designed to examine the immunomodulatory effects of dietary docosahexaenoic acid (DHA) in the absence of eicosapentaenoic acid (EPA). We investigated the effects of feeding dietary DHA ethyl ester (DHA-Et) (97% pure) at levels of 4.8 wt% of the total diet and of feeding EPA ethyl ester (EPA-Et) (99% pure) at 4.8 wt% on the inflammatory response in the challenge phase of the contact hypersensitivity reaction (CHR) in the ears of mice sensitized with 2,4-dinitro-1-fluorobenzene (DNFB). The effect of DHA-Et on T lymphocytes at the CHR site was examined using anti-CD4 antibodies. Furthermore, we examined the cytokines formed at the CHR site on the mRNA level. It was found that 24 h after the challenge, DHA-Et but not EPA-Et reduced the ear swelling. Infiltration of inflammatory cells, in particular, CD4-positive T lymphocytes, into the ears in the challenge phase of CHR was observed. DHA-Et reduced the infiltration of CD4-positive T lymphocytes into the ears. DHA-Et also decreased the expression of interferon-gamma, interleukin (IL)-6, IL-1beta, and IL-2 mRNA in ears. These observations suggest that DHA, but not EPA, may exert an antiinflammatory and immunosuppressive effect. The immunosuppressive effectiveness of fish oil may be attributed mainly to DHA.
authors.affiliation: Tsukuba Research Laboratory, NOF Corporation, Ibaraki, Japan.
authors.forename: Y I
authors.initials: YI
authors.lastname: Tomobe
authors.forename: K
authors.initials: K
authors.lastname: Morizawa
authors.forename: M
authors.initials: M
authors.lastname: Tsuchida
authors.forename: H
authors.initials: H
authors.lastname: Hibino
authors.forename: Y
authors.initials: Y
authors.lastname: Nakano
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003877:Dermatitis, Contact / Q000276:immunology / Q000517:prevention & control*; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000627:therapeutic use*; D004139:Dinitrofluorobenzene / Q000276:immunology; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000627:therapeutic use*; D004423:Ear; D005260:Female; D015870:Gene Expression; D007109:Immunity / Q000187:drug effects*; D007124:Immunoenzyme Techniques; D007249:Inflammation / Q000517:prevention & control*; D007371:Interferon-gamma / Q000235:genetics; D007375:Interleukin-1 / Q000235:genetics; D007376:Interleukin-2 / Q000235:genetics; D015850:Interleukin-6 / Q000235:genetics; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D004042:Dietary Fats, Unsaturated; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D012333:RNA, Messenger; D004281:Docosahexaenoic Acids; D007371:Interferon-gamma; D004139:Dinitrofluorobenzene