Identification,Probiotic Characterization And Anti-Helicobacter Pylori Activities Of Lactobacillus Paracasei ZFM54

Helicobacter pylori is the most prevalent and successful pathogen causing chronic gastritis,gastroduodenal ulcers and gastric tumors.It is asymptomatically present in 50 % of the world's population and a major predisposing factor for cancer.The emergence of resistant H.pylori strains to antibiotics is yet another challenge to treat the infection.Even if the infection is treated the risk of recurrence is a prevailing problem.The efficacy of lactic acid bacteria(LAB)have been extensively studied to have beneficial impact on health in a number of diseases including H.pylori infection.Lactobacilli with potential probiotic characteristics are efficient candidates to be used as beneficial therapeutic agents for numerous disease conditions.Different mechanisms have been implicated for the actions of probiotic against pathogens including immune modulation,competitive exclusion,secretion of antimicrobials,microbiota restoration.Probiotic actions are specific and cannot be implicated to every identified strain,therefore,it is crucial to investigate efficacy of individual strains.Beside chronic inflammation and oxidative stress,H.pylori is known to cause imbalance in gastric microbiota.Efficacy of probiotics to ameliorate H.pylori mediated inflammation has been widely studied while the studies on probiotics efficacy to restore gastric microbiota are poorly researched.This research is focused on investigating the potential of newly identified Lactobacillus strain Lactobacillus paracasei ZFM 54 to ameliorate H.pylori mediated inflammation and gastric dysbiosis in mice model of H.pylori infection using pretreatment and treatment approach.The strain L.paracasei ZFM 54 was isolated from healthy infant's feces and prior to investigation of anti-H.pylori potential,the strain was identified by genome sequencing and biochemical tests followed by probiotic characterization.The strain L.paracasei ZFM54 possesses probiotic associated genes and showed potential probiotic characteristics in terms of survival in harsh environment and activity against Gram positive and Gram negative pathogens.It was found to be sensitive to all antibiotics tested and did notshow any adverse effect during acute oral toxicity test in mice.In in vitro anti-H.pylori activity the strain L.paracasei ZFM54 significantly inhibit H.pylori and urease enzyme with same efficacy as shown by well known strain L.rhamnosus GG which was used as a reference strain.Antioxidation activity,aggregation and co-aggregation with H.pylori were observed in in vitro studies.In pretreatment and treatment experiment in mice,the strain ZFM54 significantly inhibit H.pylori mediated inflammation as observed by Hematoxylene and Eosin staining of mice stomach tissues and down-regulated the expression of proinflammatory cytokines IFN-?,IL-1? and IL-6.The level of malondialdehyde(MDA)in liver tissues was reduced and level of glutathione(GSH)was increased in both pretreatment and treatment groups.The strain ZFM54 also restores the gastric microbiota and decrease the relative abundance of bacterial taxa belonging to the phylum Proteobacteria as observed by linear discriminant analysis effect size(LEfSe).Taken together,these findings suggest that the strain L.paracasei ZFM 54 has the potential to protect against H.pylori infection by ameliorating inflammation,reducing MDA level in liver tissues with subsequent increase in GSH,and restoring gastric microbiota changes brought about by H.pylori infection in mice.These findings are the first to demonstrate efficacy of Lactobacillus strain to ameliorate H.pylori mediated inflammation and restore changes in stomach microbiota both in pretreatment and treatment experiments.