Lactobacillus casei Shirota intervention modulates the esophageal microbiome composition in Barrett esophagus

ObjectiveEsophageal adenocarcinoma (EAC) and its precursor, Barretts esophagus (BE), are associated with a pro-inflammatory, Gram-negative-dominated esophageal microbiome. We investigated whether Lactobacillus casei Shirota (LcS) consumption could shift the microbiome towards a more Gram-positive profile in BE patients. DesignIn a single-arm intervention study, 23 BE patients used LcS twice daily for 4 weeks. Endoscopic biopsies from normal squamous epithelium (NSE) and metaplastic columnar epithelium (MCE), both before and after LcS-intervention were analyzed using 16S rRNA gene sequencing for microbiome composition, digital droplet PCR for Gram-positive to negative ratio, and fluorescence in situ hybridization to visualize Eubacteria and Firmicutes. ResultsLcS intervention increased Gram-positive Firmicutes in MCE in situ (p<0.01) while the overall abundance of Eubacteria was unaffected. Analysis at DNA level showed an increased Gram-positive to Gram-negative ratio post-LcS. The abundance of Gram-negative Proteobacteria lowered from 74% pre-LcS to 52% post-LcS, while the abundance of Gram-positive Firmicutes, including the genus Lactobacillus, increased from 20% pre-LcS to 31% post-LcS. Overall microbiota diversity significantly increased post-LcS (p=9.9778e-07). LcS intervention also resulted in an increased abundance in the BE associated taxa Prevotella and Haemophilus in both NSE as MCE. ConclusionLcS consumption significantly altered esophageal microbiome composition in BE patients, increasing Gram-positive taxa and overall diversity. These findings underscore the potential of probiotic-based therapeutic strategies aimed at EAC prevention. The concurrent rise in BE-associated taxa warrants careful consideration and further personalized studies to maximize benefits and minimize unintended consequences for optimal outcomes in BE patients. Significance of this studyO_ST_ABSWhat is already known on this subject?C_ST_ABSO_LIEpidemiological studies point to esophageal microbiota as a risk factor for BE. C_LIO_LIGram-positive bacteria are closely associated with the normal distal esophagus, while Gram-negative bacteria (Veillonella, Prevotella, Haemophilus, Neisseria, and Fusobacterium) are increased in BE and EAC. C_LIO_LILcS has been shown to have potent anti-tumor & anti-metastatic effects on colon and gastric cancer cells and to suppress chemically-induced carcinogenesis in animals. C_LI What are the new findings?O_LIThe microbiota of both normal squamous epithelium and post-LcS samples show a higher microbiota diversity, indicating greater richness and evenness in the distal esophagus after LcS intervention. C_LIO_LILcS intervention led, at the phylum level, to a significant increase in the relative abundance of health-associated, Gram-positive Firmicutes, increasing from 22% to 32% (***p [&le;] 0.005). Gram-negative Proteobacteria showed a reduction from 72.0% to 54% (***p [&le;] 0.005). C_LIO_LIAlthough LcS intervention led to an increase in Gram-positive Firmicutes, including Lactobacillus, it also resulted, in both normal squamous epithelium and metaplastic columnar epithelium, in an increased abundance of bacterial taxa associated with BE and EAC, including the genera Prevotella and Haemophilus. C_LI How might it impact on clinical practice in the foreseeable future?O_LIOur results suggest that the esophageal bacterial composition in BE patients can be modified by consumption of dairy products containing probiotics. Manipulation of microbiota aimed at altering microbiota composition to include higher abundances of health-associated Gram-positive taxa may provide a novel way for disease prevention and therapeutic intervention. C_LI