Muscle strength is increased in mice that are colonized with microbiota from high-functioning older adults

Authors: FIELDING, ROGER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; REEVES, ANDREW - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; JASUJA, RAVI - Harvard University; LIU, CHRISTINE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BARRETT, BRITTANY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; LUSTGARTEN, MICHAEL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Experimental Gerontology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2019
Publication Date: 9/4/2019
Citation: Fielding, R.A., Reeves, A.R., Jasuja, R., Liu, C., Barrett, B.B., Lustgarten, M.S. 2019. Muscle strength is increased in mice that are colonized with microbiota from high-functioning older adults. Experimental Gerontology. 127. https://doi.org/10.1016/j.exger.2019.110722.
DOI: https://doi.org/10.1016/j.exger.2019.110722

Interpretive Summary: Evidence in support of a gut-muscle axis has been reported in rodents, but studies in older adult humans are limited. Accordingly, we compared gut microbiome composition in older adults that had a favorable body composition and good physical function (defined as high-functioning, HF, n=18) with older adults that had a less favorable body composition and worse physical function (defined as low-functioning, LF, n=11). In addition, we evaluated a causative role for the gut microbiome by transferring fecal samples from older adults into microbiome-free mice. Bacteria were identified that were different when comparing HF, when compared with LF older adults, and when comparing mice that were colonized with fecal samples from HF, when compared with LF-colonized mice. Muscle strength was significantly increased in HF-, when compared with LF-colonized mice. In contrast, the percentage of whole body lean mass and treadmill endurance capacity were not different when comparing mice that were colonized with fecal microbiomes from HF and LF older adults. In sum, these data suggest a role for gut bacteria on the maintenance of muscle strength, but argue against a role for gut bacteria on the maintenance of the percentage of whole body lean mass or endurance capacity, findings that collectively add to elucidation of the gut-muscle axis in older adults.

Technical Abstract: Evidence in support of a gut-muscle axis has been reported in rodents, but studies in older adult humans are limited. Accordingly, the primary goals of the present study were to compare gut microbiome composition in older adults that differed in terms of the percentage of whole body lean mass and physical functioning (high-functioning, HF, n=18; low-functioning, LF, n=11), and to evaluate the causative role of the gut microbiome on these variables by transferring fecal samples from older adults into germ-free mice. Family-level Prevotellaceae, genus-level Prevotella and Barnesiella, and the bacterial species Barnesiella intestinihominis were higher in HF older adults at the initial study visit, at a 1-month follow-up visit, in HF human fecal donors, and in HF-colonized mice, when compared with their LF counterparts. Grip strength was significantly increased by 6.4% in HF-, when compared with LF-colonized mice. In contrast, despite significant differences for the percentage of whole body lean mass and physical functioning when comparing the human fecal donors, the percentage of whole body lean mass and treadmill endurance capacity were not different when comparing human microbiome-containing mice. In sum, these data suggest a role for gut bacteria on the maintenance of muscle strength, but argue against a role for gut bacteria on the maintenance of the percentage of whole body lean mass or endurance capacity, findings that collectively add to elucidation of the gut-muscle axis in older adults.