Screening And Clinical Functional Evaluation Of Lactobacillus With Co-aggregation Ability Of Helicobacter Pylori

Helicobacter pylori（H.pylori）is a common pathogen and the infection rate of H.pylori is over 50%worldwide.It was regarded as a major pathogenic factor for lots of gastrointestinal diseases even gastric cancer.Considerable studies have demonstrated that Lactobacillus can alleviate H.pylori infection through the Co-aggregation between strains.This interaction can reduce H.pylori colonization by attaching to pathogenic and blocking their adhesion sites.At present,studies on screening potential probiotics through co-aggregation are mainly focused on the strain Limosilactobacillus reuteri（L.reuteri）DSMZ17648 and further several clinical trials showed that treatment with this strain can relieve H.pylori infection of patients.Therefore,this study intend to screened Lactobacillus strains with better co-aggregation ability than positive strains L.reuteri DSMZ17648.And then,we designed a series of experiments,included cells,animal and clinal trials,to evaluate the efficacy of these Lactobacillus strains against H.pylori infection.The main results of the study are as follows:Firstly,72 Lactobacillus strains were screened in vitro co-aggregation screening model and 18 Lactobacillus strains with strong co-aggregation ability（coaggregation rate is more than53.71±2.34%）were obtained.Then,the inhibitory ability of the 18 Lactobacillus strains on the adhesion of H.pylori to Human gastric adenocarcinoma cell line（AGS）were determined through cell model.The results showed that 12 strains were significantly inhibited the adhesion of H.pylori to AGS cells.Among these strain,Lacticaseibacillus paracasei（L.paracasei）17301（H.pylori adhesion rate is 4.49±1.39%）,L.paracasei VCQYo Y1157M2（H.pylori adhesion rate is 37.78±3.09%）and Limosilactobacillus fermentum（L.fermentum）FBJSYZ21-1（H.pylori adhesion rate is 39.86±2.94%）showed more positive effect than other strains.L.paracasei FJSCZD2L3（coaggregation rate is 41.89±0.85%）and L.fermentum FJSWX25-2（coaggregation rate is 44.48±1.46%）were used as negative controls to determine the inhibition of H.pylori adhesion to AGS cells.The result demonstrated that Lactobacillus with strong coaggregation in vitro could exhibit significant inhibition of H.pylori adhesion to AGS cells.Secondly,mouse with H.pylori infection was established to evaluate the alleviative effect of Lactobacillus strains with significant differences in inhibition of H.pylori abilities in vitro.Results showed that the infection rate of H.pylori-infected mice was reduced,and the gastric inflammation was improved after Lactobacillus treatment.Compared with DSMZ17648（eradication rate is 75%）,L.paracasei 17301（eradication rate is 100%）and L.fermentum FBJSYZ21-1（eradication rate is 75%）also significantly improved the eradication rate.Meanwhile,the correlation analysis showed that the co-aggregation ability of Lactobacillus was strongly correlated with the eradication rate of H.pylori-infected mice（correlation coefficient is 0.95）.Finally,a randomized,double-blind,placebo-controlled trial was conducted in the People’s Hospital of Tinghu District,Yancheng City,Jiangsu Province（Ethics number:ET2021085）,aimed to evaluate the effects of 2 Lactobacillus strains（L.paracasei 17301 and L.fermentum FBJSYZ21-1）with positive performance in vitro and in vivo.A total of 90 H.pylori-positive patients were recruited for the clinical trial.After randomly allocated into 3 groups,the subjects received 4 weeks of intervention treatment,and then the index tests were performed to evaluate the effectiveness of Lactobacillus in alleviating H.pylori infection.Clinical trial showed that Lactobacillus strains could relieve H.pylori infection,including reducing the value of ¹⁴C-Urea breath test（UBT）,increasing the rate of conversion,and alleviating the gastrointestinal symptoms.L.paracasei 17301（71.26%reduction in the value of UBT）and L.fermentum FBJSYZ21-1（65.84%reduction in the value of UBT）were better than DSMZ17648（20%reduction in the value of UBT）.Besides,the experimental results did not find that Lactobacillus intervention would adverse effect the intestinal flora and blood indicators of the subjects adversely.In conclusion,this study obtained 2 Lactobacillus strains（L.paracasei 17301 and L.fermentum FBJSYZ21-1）with strong co-aggregation ability by in vitro screening and animal evaluation.Clinical trial demonstrated that both strains were able to reduce the value of ¹⁴C-UBT and improve gastrointestinal symptoms without effecting the basic physiological status adversely.