Tea Extracts Ameliorate Dextran Sulfate Sodium-induced Colitis In Mice By Modulating Gut Microbiota Composition

Inflammatory bowel disease(IBD)has posed serious threats to human health,which lead to chronic malabsorption of nutrients,abnormal pain,and rectal bleeding.Both genetic predisposition and environmental factors contribute to the onset of IBD.By modulating the intestinal flora,diet patterns can also affect the onset of colon inflammation.Both high-fat and high-sugar diets can increase the prevalence of IBD.In contrast,dietary fruit and vegetable intake is associated with a reduced risk of IBD.The most common IBD treatments such as 5-aminosalicylate and immunomodulators have shown serious side effects.Therefore,dietary intervention may be a new target for the treatment of IBD.Tea contains bioactive ingredients such as polyphenols,amino acids,and alkaloids.Studies have shown that tea exhibited protective effect against inflammatory diseases and regulating intestinal microorganisms.Due to the differences in processing methods,tea leaves can be divided into six categories,including green tea,white tea,yellow tea,oolong tea,black tea,and dark tea.The differences in processing methods and raw material varieties lead to different levels of contained biochemical components because different teas have different physiological functions.The characteristic agricultural product of Chongqing,hawk tea,has higher content of flavonoids,and has physiological activities such as anti-inflammatory and liver protection.At present,studies have shown that green tea and black tea have a better relief effect on IBD,while the effects of other four types of tea on IBD have not been reported.At the same time,based on the important role of intestinal microorganisms in the pathogenesis and treatment of IBD,the regulating effect of tea on intestinal microorganisms in individuals with IBD is also worthy of further research.In this paper,the protective effects of six tea and eagle tea on dextran sulfate sodium(DSS)-induced colitis mice and their regulating effects on intestinal microorganisms were studied.Also,based on the method of fecal microbial transplantation,the protective effects of intestinal microorganisms regulated by green tea and dark tea in mice on colitis in mice was explored.The main results are as follows:1.Green tea(GTE),white tea(WTE),yellow tea(YTE),oolong tea(OTE),black tea(BTE),black tea(DTE),and eagle tea(HTE)extracts were prepared by hot water extraction.The constituents of polyphenols,flavonols,glycosides,amino acids and alkaloids of these seven tea extracts were determined by high performance liquid chromatography.The results showed that the content of polyphenols and amino acids was the highest in GTE,and the content of flavonols and glycosides in HTE was the highest.The highest level of gallic acid is in DTE.2.In vitro cell experiments show that the seven tea extracts exhibited anti-inflammatory effects on lipopolysaccharide-induced macrophage inflammation models.Tea extract(TE)significantly inhibited the expression of pro-inflammatory cytokines(IL-6,IL-12,TNF-α)and reactive oxygen species and increased the expression of anti-inflammatory cytokine IL-10.3.In vivo experiments show that the seven types of tea extracts alleviate weight loss and colon shortening in mice;TEs alleviated intestinal inflammation in mice by reducing pro-inflammatory cytokines and myeloperoxidase activities,and increasing anti-inflammatory cytokines;The intestinal integrity of the mice was maintained by reducing the loss of tight junction proteins ZO-1 and occludin caused by DSS;TEs alleviated liver and kidney damage caused by DSS.At the same time,TEs significantly inhibited the activation and transport of nuclear factor-κB,which may be related to the anti-colitis activity of TEs.TEs can produce a prebiotic effect on the gut microbiota by increasing the abundance of potentially beneficial bacteria(such as Faecalibaculum and Bifidobacterium)and reducing the abundance of potentially harmful bacteria(such as Bacteroids and Mucispirillum).TEs can restore the reduction of short-chain fatty acid production in the stool of colitis mice.In the above experiments,both GTE and DTE showed better protective effects than other TEs.4.Three groups of mice were administrated with drinking water,GTE,and DTE continuously for one month to culture fecal microbiota transplant(FMT)donors.The results showed that long-term administration of GTE and DTE did not produce significant toxic effects on mice;GTE and DTE showed different regulatory effects on intestinal microorganisms due to the huge differences in their phytochemical components.However,in general,GTE and DTE increased the relative abundance of beneficial bacteria(such as Lactococcus and Akkermansia),and inhibited the relative abundance of potentially harmful bacteria(such as Turicibacter and Parasutterella)compared to drinking water.Therefore,from the perspective of the composition of intestinal microorganisms,GTE and DTE-regulated intestinal microorganisms might ameliorate colitis.5.The FMT experiments were done using the fecal microbiota materials from the donors.Fecal microorganisms from drinking water(i.e.,Normal group),GTE(i.e.,GTE group),and DTE(i.e.,DTE group)mice all ameliorated DSS-induced colitis in mice.Among them,compared with the fecal microorganisms of Normal group mice,transplanting the fecal microorganisms from the GTE and DTE groups mice significantly relieved the colitis symptoms,including weight loss,increases of pro-inflammatory cytokines(IL-1β and TNF-α),loss of goblet cells and colon tissue integrity,and increased the expression of the anti-inflammatory cytokine IL-10.High-throughput sequencing showed that FMT treatment alleviated DSS-induced colitis in mice.Compared with the faecal microbiota from the Normal group,GTE and DTE-modulated fecal microbiota have a better effect on relieving weight loss,reducing the expression of pro-inflammatory cytokines,and increasing the expression of anti-inflammatory cytokines.From the analysis of intestinal microbial components,the feces of mice in the Normal group reduced the relative abundance of potentially harmful bacteria Bacteroides and Parasutterella;while the fecal microbiota of mice in the DTE group significantly increased the probiotic Akkermansia and reduced the relative abundance of the potentially harmful bacteria Desulfovibrio,Lachnoclostridium,Bacteroides uniformis,and Alistipes finegoldii;and DTE significantly increased the potential probiotics Bifidobacterium,and reduced the relative abundance of potentially harmful bacteria Bacteroides,Lachnoclostridium,and Alistipes finegoldii.Compared with the fecal microbiota from the mice in the Normal group,the fecal microbiota from the GTE and DTE groups increased the probiotic relative abundance in DSS colitis mice to a greater extent,while reducing more potential harmful bacteria in DSS colitis mice.This may be the reason why the anti-colitis effect of transplantation of fecal microbiota from the GTE and DTE groups exhibited stronger protective effects against colitis than that from the Normal group.Compared with the fecal microbiota from the Normal gourp,the fecal microbiota from the GTE and DTE groups significantly inhibited colitis associated upregulations of TLR4/MyD88/NF-κB pathway,which may be one of the molecular mechanisms of the anti-colitis of the FMT treatment from the GTE and DTE treated mice.