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Background: This study investigated the effect of different [omega]-6/[omega]-3 polyunsaturated fatty acid (PUFA) ratios on dextran sulfate sodium (DSS)-induced changes to small intestinal intraepithelial lymphocyte (IEL) [gamma][delta]T-cell expression.

Methods: Mice were assigned to 3 control and 3 DSS-treated groups and were maintained on a low-fat semipurified diet. One of the control (S) groups and a DSS (DS) group were provided with soybean oil; the other 2 control (H[omega]-3 and L[omega]-3) groups and 2 other DSS (DH[omega]-3 and DL[omega]-3) groups were fed either a soybean and fish oil mixture with a [omega]-6/[omega]-3 ratio of 2:1 or 4:1. After feeding the respective diets for 2 weeks, the DSS groups were given distilled water containing 2% DSS, and the control groups were given distilled water for 5 days. All groups were further provided distilled water 5 days for recovery, and the small intestinal IEL [gamma][delta]T-cell subset was isolated for analysis.

Results: DSS treatment resulted in a lower small intestinal IEL [gamma][delta]T-cell percentage and higher messenger RNA (mRNA) expressions of Reg III[gamma], keratinocyte growth factor (KGF), and complement 5a receptor (C5aR) by IEL [gamma][delta]T cells. Fish oil administration enhanced the proportion of small intestinal IEL [gamma][delta]T cells. Compared with the DL[omega]-3 group, the DH[omega]-3 group had lower Reg III[gamma], KGF, and C5aR mRNA expressions and higher expression of peroxisome proliferator-activated receptor (PPAR)-[gamma] gene by small intestinal IEL [gamma][delta]T cells.

Conclusions: Fish oil diets with a [omega]-6/[omega]-3 PUFA ratio of 2:1 were more effective than those with a ratio of 4:1 in improving DSS-induced small intestinal injury, and activation of PPAR-[gamma] in IEL [gamma][delta]T cells may be associated with resolution of small intestinal inflammation.

(C)2016Sage Publications