以卵蛋白致敏小鼠模式探討攝食山藥對過敏性氣喘的影響

The effect of yam feeding on allergic asthma in OVA-sensitized mouse model

羅文音(Wen-Yin Lo)

指導教授 ： 林璧鳳

國立臺灣大學/生命科學院/微生物與生化學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.01735

摘要

本研究主要探討山藥對發炎相關疾病的影響，首先以細胞培養探討台農二號山藥 ( Dioscorea alata L. cv. Tainung No.2 ) 乙酸乙酯 ( EA ) 萃取物對巨噬細胞株RAW 264.7及小鼠初代細胞免疫調的作用。發現山藥EA萃物能顯著降低巨噬細胞及小鼠初代腹腔細胞IL-6的分泌，也顯著降低小鼠初代脾臟細胞IFN-、IL-4及IL-10的分泌。在體外試驗初步觀察到山藥EA萃物具有抗發炎的潛力及調節免疫反應的效果。接著分別探討攝食熟山藥粉及山藥EA萃物對致敏小鼠過敏性氣喘的影響。BALB/c小鼠7周大時，以卵蛋白 ( ovalbumin, OVA ) 伴隨氫氧化鋁為佐劑隔週腹腔致敏以誘發其過敏體質，三次致敏之後，以OVA特異性抗體IgE含量將小鼠分為四組，分別為餵食AIN-76飼料的控制組、AIN-76飼料含0.9% 熟台農二號熟山藥粉的DA-cook組，每天管餵100 g或200 g台農二號山藥乙酸乙酯萃物的DAEA-1X組及DAEA-2X組。餵食期間以OVA做二次吸入性致敏，餵食10天後，以methacholine (Mch) 刺激小鼠進行呼吸道阻力 (AHR) 測試，結果發現，DAEA-2X組、DA-cook組及DAEA-1X組分別在25 mg/mL及50 mg/mL Mch刺激下，呼吸阻力係數PEnh值顯著低於控制組。餵食達15天後犧牲小鼠，採集血液、肺氣管沖洗液與培養脾臟及腹腔細胞。結果顯示， DA-cook組、DAEA-1X組、DAEA-2X組的脾臟細胞在OVA刺激之下，其Th2細胞激素IL-4與IL-5分泌量顯著低於控制組，腹腔細胞分泌的IL-6則有降低的趨勢。並且，肺氣管沖洗液中總細胞數目、嗜伊紅白血球及嗜中性白血球的比例、Th2 細胞激素IL-4、IL-5，IL-10，IL-13與促發炎細胞激素IL-6，PGE2含量，皆明顯低於控制組。此外，血清中總IgE生成量也顯著低於控制組。由以上結果可知，台農二號山藥能夠降低過敏小鼠Th2細胞激素的分泌、減少過敏性抗體IgE的生成、並降低促發炎介質的分泌，因此有助於減緩過敏性氣喘的症狀，深具開發的潛力。

關鍵字

山藥 ； 氣喘 ； 細胞激素 ； 呼吸道發炎

並列摘要

The purpose of this study is to evaluate whether the yam may possess an immunomodulation effect. First, the effect of ethyl acetate extract of Taiwanese Yam ( Dioscorea alata L. cv. Tainung No.2 ) ( DAEA ) on in vitro cytokines secretions by RAW 264.7 cell and primary macrophages and splenocytes from BALB/c mice was investigated. The results showed that 50 g/mL and 40 g/mL DAEA significantly inhibited IL-6 secretion in LPS-stimulated RAW264.7 and primary macrophages. ConA-stimulated IFN-, IL-4, IL-10 secretions under DAEA treatment also significantly reduced. Therefore, yam may have an anti-inflammatory and immunoregulatory effect.
Based on the results from cell culture experiments, we further used an in vivo OVA-sensitized mouse model to evaluate the effect of yam on allergic asthma. Female BALB/c mice were first sensitized with ovalbumin (OVA) in Al(OH)3 adjuvant intraperitoneally. After three times of sensitization, mice were divided into four groups by OVA-IgE titers. Four groups of mice were either fed an AIN-76 diet ( control ), AIN-76 diet containing 0.9% cooked yam ( DA-cook ), tube-feeding of 100 ( DAEA-1X ) or 200 g ( DAEA-2X ) EA extracts of yam per day. During the feeding period, mice were challenged with OVA aerosol twice to induce bronchoconstriction. The results showed that DA-cook, DAEA-1X and DAEA-2X groups significantly attenuated methacholine-induced airway hyperresponsiveness. After feeding for fifteen days, mice were sacrificed for further analysis. Compared to the control group, the DA-cook, DAEA-1X and DAEA-2X groups inhibited Th2 cytokines such as IL-4, IL-5, IL-10 secretions by splenocytes and suppressed the IgE productions in serum. The count of total cells and the distribution of eosinoiphil and neutrophil in bronchoalveolar fluid (BALF) were decreased in the DA-cook, DAEA-1X and DAEA-2X groups. The Th2 cytokines and inflammatory indicators of BALF such as IL-4, IL-5, IL-6, IL10, IL-13, PGE2 were all lessened by yam-feeding groups. In conclusion, these results suggest yam extract could alleviate allergic asthma through suppression of Th2 cytokines, pro-inflammatory mediators and serum IgE levels. Dioscorea alata L. cv. Tainung No.2 used in this study may be beneficial for patient of allergic asthma and it need to be further studied.

並列關鍵字

yam ； asthma ； cytokine ； IgE

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