LONGITUDINAL MULTI-OMIC ANALYSIS OF THE EFFECTS OF INACTIVITY AND EXERCISE ON THE HUMAN MICROBIOME UNDER CONDITIONS OF SIMULATED MICROGRAVITY

Abstract

The Canadian Ageing and Inactivity Study was the first Canadian head-down tilt bedrest study carried out in older adults to evaluate parallels between the effects of microgravity and biological ageing. Host-associated microorganisms are key regulators of physiological processes, and may influence healthy ageing trajectories. Here we combine 16S rRNA gene, metagenomic and untargeted metabolomic analysis on fecal and salivary samples of study participants, who underwent fourteen days of bedrest with or without a daily multi-modality exercise countermeasure. Our results suggest that physical activity may influence the human microbiome during spaceflight and ageing by modulating intestinal biodiversity, barrier-promoting, short-chain fatty acid producing and possibly pathogenic taxa, amino acid and vitamin biosynthesis pathways, and abundance of fecal secondary bile acids and aromatic amino acid catabolites. Oral nitrate-reducing taxa may also be affected. Our results suggest that most changes are reversible upon return to normal conditions, and that exercise has considerable protective effects.