| 摘要: | 發炎性腸道疾病為致病機制不明之消化道反覆發炎疾病，其中體內輔助型T細胞(helper T lymphocyte, Th)與調節型T細胞(regulatory T lymphocyte, Treg)失衡為影響腸道發炎的重要因子。n-3多元不飽和脂肪酸(polyunsaturated fatty acids, PUFAs)具免疫調節的功能並可緩解發炎反應。本實驗探討飲食中不同的n-6 / n-3 PUFAs比例，對於腸炎時期的免疫調控與發炎反應間之相關性。動物隨機分為3組非腸炎組(C、LF、HF組)及3組腸炎組(DC、DLF、DHF組)，C及DC組餵食一般半純化飲食，其餘組別則持相同飲食但以魚油部分替代大豆油之型式供應；C與DC組飲食中n-6 / n-3 PUFAs = 7 : 1、LF及DLF組飲食中n-6 / n-3 PUFAs = 4 : 1、HF及DHF組飲食中n-6 / n-3 PUFAs = 2 : 1。連續餵食上述飲食2週後，於腸炎組之飲水添加2% Dextran sulfate sodium連續5天，再予以正常飲水5天並於隔日犧牲。結果顯示，非腸炎組間在各分析項目皆無統計差異。血液中Th與Treg次群比率部分，DLF及DHF組顯著較DC組減少Th1、Th2及Th17次群比率，並增加Th22與Treg次群表現；DC組血漿haptoglobin及interleukin (IL)-6濃度、大腸沖洗液中prostaglandin E2、leukotriene B4、immunoglobulin (Ig) A、IgG、monocyte chemoattractant protein-1、tumour necrosis factor (TNF) -α、IL-6與IL-1β濃度皆較C組高，但DLF與DHF組則皆低於DC組。大腸組織mRNA表現量方面，DLF及DHF皆顯著較DC組降低heat shock protein 72、mucin 2、trefoil factor family 3、IL-17A、TNF-α及keratinocyte-derived chemokine。因此，經調整飲食中n-6 / n-3 PUFAs為4 : 1 - 2 : 1，可調控Th與Treg平衡並降低發炎反應，進而減緩疾病嚴重度，且n-6 / n-3 PUFAs為2 : 1較4 : 1的效果佳。
Inflammatory bowel disease (IBD) is a relasing and remitting disorder with inflammation of the gastrointestinal tract. The pathogenic mechanisms of IBD remain unknown. n-3 polyunsaturated fatty acids (n-3 PUFAs) were found to have anti-inflammatory and immune modulatory properties. This study evaluated the effect of different dietary n-6 / n-3 PUFAs ratio on helper T lymphocyte (Th) / Regulatory T lymphocyte (Treg) modulation and inflammatory response in mice with dextran sulfate sodium (DSS)-induced colitis. Mice were randomly assigned to 6 groups with 3 non-colitis groups (C, LF, HF) and 3 colitis groups (DC, DLF, DHF). C and DC groups were fed with a common semipurified diet, whereas other groups received an identical component except that part of the soybean oil was replaced by fish oil. The ratio of n-6 / n-3 PUFAs in C and DC groups were 7 : 1, LF and DLF groups were 4 : 1, HF and DHF groups were 2 : 1. After feeding the respective diets for 2 weeks, the colitis groups drank distilled water containing 2% DSS, while the non-colitis groups were given distilled water for 5 days. After that, all mice drank distilled water for another 5 days. The results showed that colitis resulted in higher haptoglobin and interleukin (IL)-6 concentrations in plasma, pro-inflammatory chemokines and immunoglobin including prostaglandin E2, leukotriene B4, immunoglobulin (Ig) A, IgG, monocyte chemoattractant protein-1, tumour necrosis factor (TNF) -α, IL-6 and IL-1β concentrations in colon lavage fluid (CLF). DLF and DHF groups had lower inflammatory mediators in plasma and CLF. Also, the percentages of blood Th1, Th2 and Th17 cells were lower whereas Th22 and Treg cell percentages were higher than the DC group. Furthermore, colitis groups with fish oil supplementation resulted in lower heat shock protein 72, mucin 2, trefoil factor family 3, and inflammatory cytokine mRNA expressions in colon tissues than the DC group. These findings suggest that diets with n-6 / n-3 PUFAs ratio 2 : 1 or 4 : 1 regulate the Th/Treg balance, reduce colon tissue damage, attenuate inflammatory mediator production in colitis. Compared with n-6 / n-3 PUFAs ratio 4 : 1, n-6 / n-3 PUFAs ratio 2 : 1 is more effective in reducing inflammatory reactions and maintain the integrity of intestinal mucosa layer in DSS-induced colitis. |
