基于肠道菌群和短链脂肪酸代谢探讨甘草制远志降低肠道炎症的作用机制

Mechanism of licorice-boiled Polygalae Radix on reducing intestinal inflammation based on intestinal flora and short-chain fatty acid metabolism

目的 研究远志甘草制前后对正常大鼠肠道菌群和短链脂肪酸(short-chain fatty acids,SCFAs)代谢的影响,探讨甘草制远志降低肠道炎症的机制。方法 SD大鼠连续15 d ig远志或制远志后,ELISA法检测十二指肠组织中炎症因子白细胞介素-6(interleukin-6,IL-6)、IL-8和肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)水平;苏木素-伊红(HE)染色观察肠组织病理变化;采用16S rDNA测序技术检测大鼠肠道菌群结构变化;运用气相色谱法测定大鼠粪便中乙酸、丙酸、丁酸、戊酸含量。结果 甘草制远志可显著降低远志引起的大鼠十二指肠组织中IL-6、IL-8、TNF-α水平升高和肠道炎症损伤(P<0.05、0.01)。16S rDNA测序结果显示,甘草制远志后可改善远志引起的大鼠肠道菌群结构改变和物种多样性减少,在门水平上主要表现为厚壁菌门(Firmicutes)和疣微菌门(Verrucomicrobia)相对丰度回升(P<0.05、0.01),拟杆菌门(Bacteroidetes)、变形菌门(Proteobacteria)和放线菌门(Actinobacteriota)相对丰度下调(P<0.05、0.01);在属水平上,远志甘草制后可上调有益菌乳酸杆菌属Lactobacillus、毛螺菌属Lachnospira、颤螺旋菌属Oscillospira等菌属的丰度(P<0.05、0.01),下调潜在的致病菌拟杆菌属Bacteroides、梭状芽孢杆菌属Clostridium等菌属的丰度。甘草制远志可一定程度逆转远志引起的大鼠粪便中乙酸、丙酸、丁酸、戊酸含量降低(P<0.05、0.01)。结论 远志引起的肠道炎症可能与其引起肠道菌群和SCFAs紊乱有关,甘草制远志可通过改善肠道菌群和SCFAs代谢来降低肠道炎症反应。

Objective To study the effects of Yuanzhi(Polygalae Radix) on intestinal flora and metabolism of short chain fatty acids(SCFAs) in normal rats before and after licorice processing,and explore the mechanism of licorice-boiled Polygalae Radix on reducing intestinal inflammation.Methods SD rats were ig Polygalae Radix or licorice-boiled Polygalae Radix for 15 d,levels of inflammatory factors such as interleukin-6(IL-6),IL-8 and tumor necrosis factor-α(TNF-α) in duodenal tissue were detected by ELISA;Pathological changes of intestinal tissue were observed by hematoxylin-eosin staining;16S rDNA sequencing technique was used to detect the structural changes of intestinal flora in rats;Contents of acetic acid,propionic acid,butyric acid and valeric acid in feces of rats were determined by gas chromatography(GC).Results Licorice-boiled Polygalae Radix significantly reduced the levels of IL-6,IL-8 and TNF-α in duodenal tissue and intestinal inflammatory damage caused by Polygalae Radix(P<0.05,0.01).The results of 16S rDNA sequencing showed that licorice-boiled Polygalae Radix could improve the structural changes of intestinal flora and decrease the species diversity caused by Polygalae Radix in rats.At the phylum level,the relative abundance of Firmicutes and Verrucomicrobia were increased(P<0.05,0.01),while the relative abundance of Bacteroidetes,Proteobacteria and Actinobacteriota were decreased(P<0.05,0.01).At the genus level,the abundance of beneficial bacteria such as Lactobacillus,Lachnospira and Oscillospira were increased(P<0.05,0.01),and the abundance of potential pathogenic bacteria such as Bacteroides and Clostridium were decreased after licorice-boiling Polygalae Radix.Licorice-boiled Polygalae Radix could reverse the decrease of acetic acid,propionate,butyric acid and valerate in rat feces caused by Polygalae Radix to a certain extent(P<0.05,0.01).Conclusion The intestinal inflammation caused by Polygalae Radix may be related to the disorder of intestinal flora and SCFAs.Licorice-boiled Polygalae Radix can reduce the intestinal inflammatory reaction by improving the metabolism of intestinal flora and SCFAs.