Modulation Of The Mice Gastrointestinal Microbiota By Lactobacillus Plantarum ZDY 2013 And Its Preventive Effects Against Helicobacter Pylori Infection

The GI tract harbors at least 100 trillion(1014) microbial cells, which plays a profound role on human health and physiology. However, most of studies focused on the distal GI tract microbiota, leaving microbiota in other parts of the GI tract, such as stomach and the small intestine, unexplored.In this study, we investigated the intervention effects of a probiotic candidate, Lactobacillus plantarum ZDY2013(LP), on gastric microbiota in a mouse model, and its preventive effect against the H. pylori infection. Furthermore, the instant and long-term modulation effects on small intestine microbiota by this strain were also explored. Quantitative real-time PCR(qPCR) and hematoxylin-eosin staining were employed to examine the gastric mucosal immune response induced by H. pylori infection, the results showed that a significant increase(p<0.05) in inflammatory cytokines(e.g. IL-1? and IFN-γ) took place in the gastric tissue and inflammatory cell infiltration in gastric lamina propria, respectively. However, in the LP pretreatment group these symptoms were well prevented or alleviated. The results suggested that LP administration can commendably prevent the gastric mucosa inflammation induced by H. pylori infection.The gastric microbiota alteration was explored by high-throughput 16 S rRNA gene amplicon sequencing. Weighted UniFrac principal coordinate analysis(PcoA) showed that LP pretreatment prevented the alteration in gastric microbiota post H. pylori infection. Linear discriminant analysis coupled with effect size(LEfSe) identified 22 bacterial taxa(e.g., Pasteurellaceae, Erysipelotrichaceae, Halomonadaceae, Helicobacteraceae and Spirochaetaceae) that overgrew in the gastric microbiota of H. pylori infected mice, and most of them belonged to the Proteobacteria phylum. LP pretreatment prevented this alteration; with only 6 taxa(e.g., Lachnospiraceae, Ruminococcaceae and Clostriciaceae) mainly from the taxa of Firmicutes and Bacteriodetes were dominant in the gastric microbiota of the LP pretreated mice. Administration of LP for three weeks led to an increase in several bacterial taxa(e.g., Rikenella, Staphlococcus, Bifidobacterium), although there was a non-significant alteration in the overall gastric microbiota.The α diversity analysis revealed that oral administration with LP for three weeks led to a significant increase(p<0.05) in the richness and diversity of small intestinal(SI) bacterial community. PcoA and Unweighted Pair-Group Method with Arithmetic Means(UPGMA) analysis presented a clear alteration in the SI microbiota composition after 3 weeks’ LP treatment, though these changes were not found at 6 weeks after stopping LP administration. Interestingly, administration with LP for three weeks significantly increased the abundance of Proteobacteria, but decreased that of Bacteroidetes. Linear discriminant analysis coupled with effect size(LEfSe) identified 18 bacterial taxa(e.g. Ruminococcus spp. and Clostridium spp., p<0.05) that overgrew in the SI microbiota in three weeks’ LP treated mice, and most of them belonged to Bacteroidetes and Proteobacteria phylum. Only one bacterial taxa(e.g. Nocardioides spp.), however, was over-presented in the SI microbiota of mice after 6 week’s stopping LP administration.Overall, the results demonstrated that LP pretreatment played an important role in preventing gastric mucosal inflammation and gastric microbiota alteration induced by H. pylori infection, the modulation in SI by this pretreatment was transient but not long-term, suggesting that oral administration of probiotics should be long-term to guarantee the stable beneficial effect for host.