1a.Objectives (from AD-416):
This project will characterize the whole blood response of healthy subjects to LGG using a select panel of cytokine and chemokine markers detected by real time PCR, and a more robust evaluation of transcriptomic changes detected prior to during and after feeding of LGG. Associations will be developed with the levels of LGG, Bifidobacterium and Lactobacillus spp. in the feces and naso-pharynx. The cooperator is interested in detecting LGG and evaluating the clinical effects in healthy adults fed LGG as part of a Phase I study to demonstrate safety strain.
1b.Approach (from AD-416):
ARS will acquire nucleic acids from whole blood PaxGene and fecal samples from treated subjects to detect specific bacterial genes and patterns of whole blood gene expression as was developed in-house using a pig model. The analysis will include Illumina-based deep sequencing of samples from subjects prior to feeding LGG, after 28 days of feeding, and 28 days after cessation of feeding. This information will be used by both ARS and the Cooperator to jointly develop studies that focus on the effects of probiotic bacteria LGG as a vaccine adjuvant. The Cooperator will collate this information with a comprehensive clinical evaluation of the subjects, including routine anaerobic culture – LGG recovery in naso-pharynx and GI tract.
Probiotics are purported to confer health benefits, but little is known about their mechanism of action. Given interest in using probiotics to promote health in the elderly, we analyzed the effect of daily intake of 2 x 1010 cfu of Lactobacillus rhamnosus GG ATCC 53103 (LGG) for 28 days on 11 healthy elderly subjects in an open label study. Subject compliance was verified by molecular detection of LGG copies in DNA isolated from fecal samples. Changes in host transcriptome were evaluated after RNA sequencing (RNA-seq) to identify differentially expressed genes (DEGs) in whole blood cells prior to consuming LGG (day 0), at the end of LGG consumption (day 28), and one month after feeding of LGG stopped. A list of DEGs after pair-wise analysis were generated using the edge-R statistical package with an FDR adjusted p-value at p=0.1. Overall, LGG consumption did not induce significant changes in the host immune response or displaced resident organisms from fecal microbiota community.