Dietary conjugated linoleic acid ameliorates CD4+-induced colitis in the RAG-2-/- adoptive transfer model

Hontecillas, R., and J. Bassaganya-Riera (2003) Dietary conjugated linoleic acid ameliorates CD4⁺-induced colitis in the RAG-2^-/- adoptive transfer model. American Association of Immunologists Annual Meeting; Denver, CO; (Late Breaking Abstract #B329).

Previously we had demonstrated that feeding diets supplemented with conjugated linoleic acid (CLA) prevented dextran sodium sulfate-induced colitis in mice. The colonic anti-inflammatory effect of CLA was observed only after an accumulation phase of 42 days. We hypothesized that colitis is ameliorated by the prolonged action of CLA on colonic CD4⁺ T cells. To test our hypothesis, 4 x 10⁵ CD4⁺CD45RB^hi T cells isolated from donor C57BL/6J mice fed either linoleic (control) or CLA-supplemented diets for 42 days were transferred into RAG2^-/- mice. Recipient mice were euthanized 6 weeks after cell transfer and colonic tissues were recovered for histopathologic examination. RAG2^-/- mice that received cells from donors fed the control diet developed severe colitis characterized by increased mucosal thickness. Lesions were milder in mice that were transferred with CD4⁺ CD45RB^hi T cells isolated from mice fed CLA. Clinically, CLA fed to the donors prevented weight loss associated with the development of colitis. Together, these results indicate that CD4⁺ lymphocytes are the cellular targets of the colonic anti-inflammatory actions of CLA. In vitro experiments have shown that CLA activates peroxisome proliferators-activated receptor-γ (PPAR-γ). Future studies will examine if the actions of CLA on CD4⁺CD45RB^hi T cells are PPAR-γ-dependent.