Rhythmic Bacteria as Biomarkers for Circadian-Related Diseases

Recent studies suggest that the human circadian clock influences periodic changes in the composition of the gut microbiota, which is essential for maintaining host health. This connection has led researchers to hypothesize that the disruption of the circadian clock may impact human health via the gut microbiota. Here, we hypothesize that rhythmic bacteria—those whose abundance fluctuates in a circadian pattern—are key drivers of the differences in gut microbiota composition between healthy individuals and those with circadian-related diseases. Even in the absence of a causal relation, identifying rhythmic bacteria associated with circadian-related diseases can reveal disease biomarkers as well as intervention strategies. To test this, we first conducted a systematic review to identify rhythmic bacteria reported in the literature. Then, we mapped these bacteria onto a reference gut microbiota dataset of nearly 4,800 healthy individuals from a previously curated metagenomic database. We use this data to assess the prevalence and abundance of bacteria. To examine significant bacteria in samples from individuals with circadian-related diseases, including type 2 diabetes, hypertension, atherosclerotic cardiovascular disease, colorectal cancer, metabolic syndrome, and inflammatory bowel disease, we compared disease datasets from several previous studies with their respective healthy controls. Of the eight rhythmic bacteria identified in previous studies, seven were among the top 100 most prevalent and abundant species in the gut. We found the rhythmic bacterium Roseburia faecis to be strongly and exclusively associated with circadian-related diseases, suggesting its use as a biomarker and possibly coadjuvant in the treatment of these diseases. Clinical trial number: not applicable.