Functional Dynamics of the Gut Microbiome in Elderly People during Probiotic Consumption

Abstract

A mechanistic understanding of the purported health benefits conferred by consumption of probiotic bacteria has been limited by our knowledge of the resident gut microbiota and its interaction with the host. Here, we detail the impact of a single-organism probiotic, Lactobacillus rhamnosus GG ATCC 53103 (LGG), on the structure and functional dynamics (gene expression) of the gut microbiota in a study of 12 healthy individuals, 65 to 80 years old. The analysis revealed that while the overall community composition was stable as assessed by 16S rRNA profiling, the transcriptional response of the gut microbiota was modulated by probiotic treatment. Comparison of transcriptional profiles based on taxonomic composition yielded three distinct transcriptome groups that displayed considerable differences in functional dynamics. The transcriptional profile of LGG in vivo was remarkably concordant across study subjects despite the considerable interindividual nature of the gut microbiota. However, we identified genes involved in flagellar motility, chemotaxis, and adhesion from Bifidobacterium and the dominant butyrate producers Roseburia and Eubacterium whose expression was increased during probiotic consumption, suggesting that LGG may promote interactions between key constituents of the microbiota and the host epithelium. These results provide evidence for the discrete functional effects imparted by a specific single-organism probiotic and challenge the prevailing notion that probiotics substantially modify the resident microbiota within nondiseased individuals in an appreciable fashion.

Impact of probiotic supplements on microbiome diversity following antibiotic treatment of mice

“…The addition of the probiotic caused a metabolic shift in the microbiota which resulted in a non-permissive environment for opportunistic pathogens. 59 A more recent report by Eloe-Fadrosh et al 43 examined the dynamics of the gut transcriptome following probiotic consumption. They identified an increase in flagellar motility, chemotaxis, and adhesion genes from resident commensal bacteria which were positively regulated by the addition of the probiotic to the host diet.…”

“…Following ingestion, these probiotic strains are rarely identified as established members of the fecal microbiota and thus their impact may require constant administration. [41][42][43] In "healthy flora" the addition of a probiotic does not readily impact the resident microbial populations. 43,44 However, in a situation exhibiting dysbiosis the addition of probiotics could have a significant impact on reshaping the microbiota.…”

“…[41][42][43] In "healthy flora" the addition of a probiotic does not readily impact the resident microbial populations. 43,44 However, in a situation exhibiting dysbiosis the addition of probiotics could have a significant impact on reshaping the microbiota. Since there is no regulatory body which has oversight of probiotics it requires the research community investigate this over the counter treatment.…”

Gleaning Insights from Fecal Microbiota Transplantation and Probiotic Studies for the Rational Design of Combination Microbial Therapies

“…The ability of probiotic strains to restore or maintain the composition of the microbiota may help prevent inflammatory immune signaling induced by dysbiosis. Probiotic administration has been shown to limit dysbiosis in many disease states, including colitis models, and to restore a normal microbiota composition more quickly than with placebo (289)(290)(291). Patients with minimal hepatic encephalopathy secondary to cirrhosis who were treated with LGG showed significantly increased prevalences of Lachnospiraceae and Clostridia cluster XIV and decreased prevalences of Enterobacteriaceae and Porphyromonadaceae relative to placebo-treated controls (292).…”

“…Probiotics can also modulate the metabolic profile of the microbiota, suggesting a means by which these organisms may help prevent alterations in the microbiota and limit dysbiosis. For example, LGG administration to healthy 65-to 80-year-old individuals induced no change in overall microbiota composition, as determined by 16S rRNA sequencing, with a few exceptions, such as increased levels of the butyrate producers Roseburia and Eubacterium (289). However, the expression levels of genes involved in bacterial motility and chemotaxis were increased in certain commensal species, including Bifidobacterium, leading to the suggestion that LGG can promote interactions between certain microbes and the host epithelium (289).…”