Endogenous Circadian System and Circadian Misalignment: Effects on Human Oral Microbiota
News Release, International Society of Microbiota – March 16, 2022.
The misalignment between the central circadian clock and behavioral and environmental cycles, "Circadian misalignment", results in adverse cardiovascular and metabolic effects. Potential underlying mechanisms for these adverse effects include alterations in the orogastrointestinal microbiota.
Up until today, it remains unknown whether human oral microbiota has endogenous circadian rhythms and whether circadian misalignment influences oral microbiota community composition. So, Chellapa et al. aimed to study the effect of endogenous circadian system and circadian misalignment effects on human oral microbiota.
- Healthy young individuals were enrolled in a stringently controlled 14-day circadian laboratory protocol. This included a 32-h constant routine (CR) protocol, a forced desynchrony protocol with four 28-h “days” under ~3 lx to induce circadian misalignment, and a post-misalignment 40-h CR protocol.
- Microbiota assessments were performed on saliva samples collected every 4 h throughout both CR protocols. Total DNA was extracted and processed using high-throughput 16S ribosomal RNA gene amplicon sequencing.
The relative abundance of specific oral microbiota populations, i.e., one of the five dominant phyla, and three of the fourteen dominant genera, exhibited significant endogenous circadian rhythms. Importantly, circadian misalignment dramatically altered the oral microbiota landscape, such that four of the five dominant phyla and eight of the fourteen dominant genera exhibited significant circadian misalignment effects.
Moreover, circadian misalignment significantly affected the metagenome functional content of oral microbiota (inferred gene content analysis), as indicated by changes in specific functional pathways associated with metabolic control and immunity.
Collectively, this proof-of-concept study provides evidence for endogenous circadian rhythms in human oral microbiota and show that even relatively short-term experimental circadian misalignment can dramatically affect microbiota community composition and functional pathways involved in metabolism and immune function. These proof-of-principle findings have translational relevance to individuals typically exposed to circadian misalignment, including night shift workers and frequent flyers.
Dr. Frank Scheer will join us in Targeting Microbiota 2022 to explain further about this fascinating study.
Read the full proof-of-concept study.
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