Study On The Effects Of Lactobacillus Plantarum ZJ316 And Its Fermented Milk To DSS-Induced Colitis In Mice

Ulcerative Colitis(UC)which is caused by allergic reactions and physical or complicated chemical factors is a kind of intestinal inflammatory disease.According to the course of disease,it can be divided into acute UC and chronic UC.For a long time,due to lack of effective therapy,the disease not only seriously endangers people’s health,but also brings double pressure and burden to patients’life and economy.Therefore,it is urgent to provid a highly effective and safe formula that is few side effects and different from ordinary drugs to prevent and control UC In recent years,more and more studies have found that lactic acid bacteria can maintain intestinal microecological balance,strengthen the intestinal mucosal barrier function,improve the intestinal inflammation,inhibit intestinal epithelial cell apoptosis,regulate intestinal metabolic balance,and enhance human immunity,and so on.So,it is of great significance to study these characteristics for the prevention and improvement of UC.In this study,lactobacillus plantarum ZJ316 which was selected from the feces of healthy infants was as the research object.Firstly,its environmental stress resistance and intestinal tolerance were investigated.Next,in order to investigate the effect of Lactobacillus plantarum ZJ316 and its fermented milk on colitis in mice,we selected the SPF grade BALB/c mice to establish the model of acute and chronic colitis by DSS,and then,Lactobacillus plantarum ZJ316 and its fermented milk were used to intervene in the model mice for five weeks,which lays a foundation for probiotics in preventing and improving intestinal diseases such as UC.The specific research results are summarized as follows:1.Study on environmental stress resistance and gastrointestinal tolerance of Lactobacillus plantarum ZJ316.By simulating the external environment and internal digestive system it can be obtained that Lactobacillus plantarum ZJ316 exhibited better tolerance to high concentration of NaCl(6%)and ethanol(10%),the survival rates were 69.53%and 45.54%respectively.Lactobacillus plantarum ZJ316 also showed good viability when exposed to gastric acid(pH 3.5)and bile salts(0.5%)for 4h,the results indicated respectively 82%and 48%.In conclusion,Lactobacillus plantarum ZJ316 not only shows strong environmental stress resistance but also has good gastrointestinal tolerance.2.Effect of Lactobacillus plantarum ZJ316 and its fermented milk on inflammatory manifestations of colitis induced by DSS in mice.The changes of body weight,length and weight of colon in mice were measured and the pathological damage of colon tissue was observed by H&E staining to explore whether Lactobacillus plantarum ZJ316 and its fermented milk coμLd improve the symptoms of DSS-induced colitis.The results showed that because of the induction of DSS the weight of mice was significantly reduced,the length of colon was significantly shortened,the weight of colon was significantly reduced,and the intestinal mucosa was severely damaged.While after the intervention of Lactobacillus plantarum ZJ316 and its fermentation milk,the weight of the colon,the length and the damaged intestinal mucosa were significantly recovered,indicating that Lactobacillus plantarum ZJ316 and its fermentation milk can alleviate the experimental colitis symptoms induced by DSS through repairing the intestinal mucosa.3.Effects of Lactobacillus plantarum ZJ316 and its fermented milk on the expression level of inflammatory cytokine in the colon of DSS-induced colitis of mice.In order to investigate the effect of Lactobacillus plantarum ZJ316 and its fermented milk on immune response in mice with colitis,the mRNA expression of cytokines were analysed via RT-qPCR.The results showed that Lactobacillus plantarum ZJ316 and its fermented milk can significantly down-regulate the pro-inflammatory cytokines(IL-1β、IL-6、IL-8 and TNF-α)in the colon of DSS-colitis mice,while they can significantly increased anti-inflammatory cytokine(IL-10 and TGF-β),which indicated that Lactobacillus plantarum ZJ316 and its fermented milk could improve the experimental colitis symptoms induced by DSS throμgh regulating the host immune response.4.Effects of Lactobacillus plantarum ZJ316 and its fermented milk on the content of short-chain fatty acids in colon of DSS-induced colitis mice.The contents of short chain fatty acids in the colon of mice in each treatment group were analyzed by GC-MS.The result showed that after DSS induction,the contents of acetic acid,propionic acid,butyric acid,isobutyric acid and valeric acid in the colon of mice were significantly reduced.While the contents of those five short chain fatty acids in colon of DSS-induced colitis mice were dramatically increased through treatment with Lactobacillus plantarum ZJ316 and its fermented milk for 5 weeks,which demonstrated that Lactobacillus plantarum ZJ316 and its fermented milk can improve metabolism disorder of short chain fatty acid caused by DSS.5.Effects of Lactobacillus plantarum ZJ316 and its fermented milk on intestinal tract microflora in the colon of DSS-induced colitis mice.Through 16SrRNA high-throughput sequencing technology,the microorganism in the colon of mice in each treatment group was detected to explore whether the imbalance of intestinal flora induced by DSS was improved by Lactobacillus plantarum ZJ316 and its fermented milk.The results showed that after being intervented by Lactobacillus plantarum ZJ316 and its fermented milk,the abundance of probiotics,such as Faecalibacterium and Lactobacillus,in the colon of mice was improved,while the abundance of pathogenic bacteria including Bacteroides,Helicobacter and Alistipes was reduced,which indicated that Lactobacillus plantarum ZJ316 and its fermented milk can modulate DSS-induced dysregulation of gut microbita.