ITS1 sequence data of the enteric mycobiota of young and aged SPF mice

Altered gut microbiota composition with ageing and altered gut-brain axis communication is increasingly being implicated in neurological and neurodegenerative diseases. Both the disruption of the gut microbiota, and the possible involvement of microbes including fungal species in the brain, have been implicated in the development of dementias such as Alzheimer's disease. Using germ-free mice, we show that the fungal gut commensal, Candida albicans, an opportunistic pathogen in humans, can traverse the gastrointestinal barrier and disseminate to brain tissue, where it can grow in an invasive hyphal form. To investigate whether the gut mycobiome is significantly affected by ageing, we characterised the faecal gut fungal composition of aged vs. young SPF mice using high-throughput ITS1 amplicon sequencing. We identify a number of putative gut commensal fungal species with pathobiont potential; however, we find their abundance does not significantly differ between young and aged mice. Collectively, these results suggest that although some fungal species are able to travel from the gut to brain where they can induce an inflammatory response, ageing alone is not correlated with significant changes in gut mycobiota composition which could predispose to these events. These results are consistent with a scenario in which significant disruptions to the gut microbiota and/or intestinal barrier, beyond those which occur with natural ageing, are required to allow fungal escape and brain infection.