富含三萜類之苦瓜葉萃取物預防性保護葡聚醣硫酸鈉引致小鼠慢性腸炎
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2021
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發炎性腸道疾病 (inflammatory bowel disease, IBD)是一種慢性、反覆性的腸道發炎性疾病。先前研究發現，自山苦瓜 (學名: Momordica charantia Linn. var. abbreviataSer.)葉片乙醇萃取物中，分離得到的富含三萜類區分萃取物 (triterpenoid-enriched extract, TEE)，可藉由調控輔助型T細胞 (helper T cells)和調節型T細胞 (regulatory T cells)，預防性緩解葡聚糖硫酸鈉 (dextran sulfate sodium, DSS)誘導小鼠急性腸炎的發炎反應，因此本研究欲進一步探討TEE是否具有治療或預防慢性腸炎的功用。本研究共進行兩次動物實驗，分述於下：實驗一為模擬治療模式，先連續7天給予C57BL/6J小鼠含有3% DSS飲水誘導腸炎後，於飼料中添加TEE (攝取劑量為100 mg/kg BW)或苦瓜葉粉末 (bitter melon leaf powder, BMLP；攝取劑量為1g/kg)持續餵食14天後犧牲，實驗期間每日紀錄體重變化，並於實驗結束後記錄器官重量，以及分析脾臟中免疫細胞與腸炎相關基因表現。實驗結果發現給予TEE或BMLP組與單獨給予DSS誘導組比較，給予TEE或BMLP並未顯著影響小鼠體重與器官重量變化、脾臟T細胞分化、腸炎相關基因和組織發炎評分，因此推斷TEE和BMLP在此劑量與實驗模式下，並無治療慢性腸炎的功效。實驗二為模擬預防模式先投與TEE，觀察TEE對於DSS誘導腸炎的急性後期與慢性期的影響。將C57BL/6J小鼠分為一般控制組 (NC組)、DSS誘導組 (DC組)、DSS+低劑量TEE (攝取劑量為100 mg/kg BW；DL組)與DSS+高劑量TEE (攝取劑量為150 mg/kg BW；DH組)。在DSS誘導腸炎前，先給予一周TEE，並分別於3% DSS誘導腸炎後第14天(急性後期)與第21天(慢性期)犧牲動物，從大腸組織切片觀察發現，與DC組比較，TEE組的組織發炎評分較低、腸道上皮結構較完整、以及嗜中性白血球的浸潤程度較低，且分杯狀細胞數量與分泌的黏液較多。由qPCR分析結果發現於誘導腸炎急性後期，給予TEE能提高大腸組織的MUC (mucin)2、ZO-1 (zonula occludens-1)、Occludin與Claudin-2 mRNA表現量，而大腸組織的MUC1、MUC4、TNF-α (tumor necrosis factor-α)、IL (interleukin)-1β與CXCL1 (chemokine (CXC motif) ligand) mRNA表現量也被TEE所抑制。於誘導腸炎慢性期時，TEE能降低大腸組織的TFF (trefoil factors)3、MUC4、TNF-α、IL-1β與CXCL1 mRNA表現量，並增加杯狀細胞數量與MUC2 mRNA的表現量。以上證據顯示TEE在大腸組織微環境具有預防性保護腸炎的效果。由流式細胞儀分析，結果發現TEE對於血液與脾臟之單核球、嗜中性球與T細胞分布並沒有顯著影響。綜合上述結果，推論TEE於大腸微環境中透過減少嗜中性白血球浸潤、減少促發炎因子、增加黏液與維持腸道屏障完整，而具有預防性保護慢性腸炎的作用。
Inflammatory bowel disease (IBD) is a chronically recurrent inflammatory disturbance in gastrointestinal tract, clinically characterized as Crohn’s disease and ulcerative colitis. Our previous study demonstrated that the protective effects of triterpenoid enriched-extract (TEE) of wild bitter melon (WBM; Momordica charantia L.var.abbreviata Seringe) leaf in mitigating dextran sulfate sodium (DSS)-induced acute colitis by regulating Th/Treg-mediated immunity and inflammatory responses. In this study, we investigated the preventive and therapeutic effects of TEE on chronic colitis in DSS-treated mice. This study consisted of two independent experiments as follows.In Experiment I, C57BL/6 mice were randomly divided into four groups: one normal control (NC) group and four DSS-treated groups, including DSS group (colitis model), DT group (DSS+ 82.4 mg/kg BW of TEE), and DP group (DSS + 804.7 mg/kg BW of bitter melon leaf powder (BMLP)). The DSS-treated groups drank distilled water containing 3.5% DSS for 7 d to induce colitis before TEE or BMLP administrations, while NC group drank distilled water. DT and DP groups was respectively administrated with AIN-93 diet containing TEE (100 mg/kg diet) and BMLP (1g/kg diet) for 14 days. Our results showed that either post-treatments of TEE or BMLP did not significantly affect body weight, colon shortening, organ weight, spleen T cell population, and inflammation-related factors. These data suggested that post-treatments of TEE or BMLP did not possess the beneficial effects on alleviating chronic colitis.In Experiment II, C57BL/6 mice were randomly divided into four groups: one normal control (NC) group and four DSS-treated groups, including DSS group (colitis model), DL group (DSS+ 100 mg/kg BW of TEE), and DH group (DSS+150 mg/kg BW of TEE). The DSS-treated groups drank distilled water containing 3% DSS for 7 days to induce colitis, while NC group drank distilled water. DL and DH groups was administrated TEE supplemented to an AIN-93 diet for 7 days before DSS-induced colitis and subsequently received TEE supplemented to an AIN-93 diet after DSS-induced colitis for 14 days (late-acute phase) and 21 days (chronic phase). Results from H&E staining of colonic tissue disclosed the distinct pathological changes upon DSS treatment, including serious epithelial disruption, inflammatory cells infiltration, and obvious decreased goblet cell number, whereas TEE led to improvements of these pathological changes. These results suggested that TEE could protect the colonic tissue from the DSS-induced damage. Next, we evaluated the mRNA levels of colonic pro-inflammatory cytokines by qPCR analysis. We found that TEE administration up-regulated MUC (mucin)2, ZO-1 (zonula occludens-1), occludin and claudin-2 mRNA levels and down-regulated colonic MUC1, MUC4, TNF-α (tumor necrosis factor-α), IL (interleukin)-1β and CXCL (chemokine (CXC motif) ligand)1 mRNA levels on Day-14. In addition, TEE administration inhibited DSS-induced TFF3 (trefoil factors), MUC4, TNF-α, IL-1β, and CXCL1 mRNA levels of colon tissue and elevated colonic goblet cells and MUC2 mRNA level on Day-21. The evidence suggested the pre-treatment of TEE exerted the protective role in attenuating chronic colitis. However, the results of flow cytometry assay showed that TEE had no influence on the proportions of monocytes, neutrophils, and Tregs in blood or spleen.IBD has been associated with mucus producing deficiency and decreased goblet cell number. These results revealed that TEE supplement may contribute to the management of colonic inflammation via regulation of neutrophils, decreasing pro-inflammatory cytokine, upregulating mucin, and improving epithelial barrier defectsin in colonic microenvironment. In conclusion, our results suggestedthat the preventive treatment of TEE plays a protective role of the mucosal layer in maintaining intestinal health.
Inflammatory bowel disease (IBD) is a chronically recurrent inflammatory disturbance in gastrointestinal tract, clinically characterized as Crohn’s disease and ulcerative colitis. Our previous study demonstrated that the protective effects of triterpenoid enriched-extract (TEE) of wild bitter melon (WBM; Momordica charantia L.var.abbreviata Seringe) leaf in mitigating dextran sulfate sodium (DSS)-induced acute colitis by regulating Th/Treg-mediated immunity and inflammatory responses. In this study, we investigated the preventive and therapeutic effects of TEE on chronic colitis in DSS-treated mice. This study consisted of two independent experiments as follows.In Experiment I, C57BL/6 mice were randomly divided into four groups: one normal control (NC) group and four DSS-treated groups, including DSS group (colitis model), DT group (DSS+ 82.4 mg/kg BW of TEE), and DP group (DSS + 804.7 mg/kg BW of bitter melon leaf powder (BMLP)). The DSS-treated groups drank distilled water containing 3.5% DSS for 7 d to induce colitis before TEE or BMLP administrations, while NC group drank distilled water. DT and DP groups was respectively administrated with AIN-93 diet containing TEE (100 mg/kg diet) and BMLP (1g/kg diet) for 14 days. Our results showed that either post-treatments of TEE or BMLP did not significantly affect body weight, colon shortening, organ weight, spleen T cell population, and inflammation-related factors. These data suggested that post-treatments of TEE or BMLP did not possess the beneficial effects on alleviating chronic colitis.In Experiment II, C57BL/6 mice were randomly divided into four groups: one normal control (NC) group and four DSS-treated groups, including DSS group (colitis model), DL group (DSS+ 100 mg/kg BW of TEE), and DH group (DSS+150 mg/kg BW of TEE). The DSS-treated groups drank distilled water containing 3% DSS for 7 days to induce colitis, while NC group drank distilled water. DL and DH groups was administrated TEE supplemented to an AIN-93 diet for 7 days before DSS-induced colitis and subsequently received TEE supplemented to an AIN-93 diet after DSS-induced colitis for 14 days (late-acute phase) and 21 days (chronic phase). Results from H&E staining of colonic tissue disclosed the distinct pathological changes upon DSS treatment, including serious epithelial disruption, inflammatory cells infiltration, and obvious decreased goblet cell number, whereas TEE led to improvements of these pathological changes. These results suggested that TEE could protect the colonic tissue from the DSS-induced damage. Next, we evaluated the mRNA levels of colonic pro-inflammatory cytokines by qPCR analysis. We found that TEE administration up-regulated MUC (mucin)2, ZO-1 (zonula occludens-1), occludin and claudin-2 mRNA levels and down-regulated colonic MUC1, MUC4, TNF-α (tumor necrosis factor-α), IL (interleukin)-1β and CXCL (chemokine (CXC motif) ligand)1 mRNA levels on Day-14. In addition, TEE administration inhibited DSS-induced TFF3 (trefoil factors), MUC4, TNF-α, IL-1β, and CXCL1 mRNA levels of colon tissue and elevated colonic goblet cells and MUC2 mRNA level on Day-21. The evidence suggested the pre-treatment of TEE exerted the protective role in attenuating chronic colitis. However, the results of flow cytometry assay showed that TEE had no influence on the proportions of monocytes, neutrophils, and Tregs in blood or spleen.IBD has been associated with mucus producing deficiency and decreased goblet cell number. These results revealed that TEE supplement may contribute to the management of colonic inflammation via regulation of neutrophils, decreasing pro-inflammatory cytokine, upregulating mucin, and improving epithelial barrier defectsin in colonic microenvironment. In conclusion, our results suggestedthat the preventive treatment of TEE plays a protective role of the mucosal layer in maintaining intestinal health.
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Keywords
腸炎, 山苦瓜葉, 含三萜類區分萃取物, 葡聚醣硫酸鈉, chronic colitis, bitter melon leaf, triterpenoid-enriched extract, dextran sodium sulfate