Circadian misalignment by environmental light/dark shifting causes circadian disruption in colon

Abstract

Background Physiological circadian rhythms (CRs) are complex processes with 24-hour oscillations that regulate diverse biological functions. Chronic weekly light/dark (LD) shifting (CR disruption; CRD) in mice results in colonic hyperpermeability. However, the mechanisms behind this phenomenon are incompletely understood. One potential innovative in vitro method to study colonic CRs are colon organoids. The goals of this study were to utilize circadian clock gene Per2 luciferase reporter (Per2::Luc) mice to measure the effects of chronic LD shifting on colonic tissue circadian rhythmicity ex vivo and to determine if organoids made from shifted mice colons recapitulate the in vivo phenotype. Methods Non-shifted (NS) and shifted (S) BL6 Per2::Luc mice were compared after a 22-week experiment. NS mice had a standard 12h light/12h dark LD cycle throughout. S mice alternated 12h LD patterns weekly, with light from 6am-6pm one week followed by shifting light to 6pm-6am the next week for 22 weeks. Mice were tested for intestinal permeability while colon tissue and organoids were examined for CRs of bioluminescence and proteins of barrier function and cell fate. Results There was no absolute difference in NS vs. S 24h circadian period or phase. However, chronic LD shifting caused Per2::Luc S mice colon tissue to exhibit significantly greater variability in both the period and phase of Per2::Luc rhythms than NS mice colon tissue and organoids. Chronic LD shifting also resulted in increased colonic permeability of the Per2::Luc mice as well as decreased protein markers of intestinal permeability in colonic tissue and organoids from shifted Per2:Luc mice. Conclusions Our studies support a model in which chronic central circadian disruption by LD shifting alters the circadian phenotype of the colon tissue and results in colon leakiness and loss of colonic barrier function. These CRD-related changes are stably expressed in colon stem cell derived organoids from CRD mice.

Circadian dysregulation induces alterations of visceral sensitivity and the gut microbiota in Light/Dark phase shift mice

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Circadian Rhythms and Melatonin Metabolism in Patients With Disorders of Gut-Brain Interactions

“…Chronodisruption from altered light-dark cycles also leads to increased intestinal permeability ( Summa et al, 2013 ) and alterations in the GIT microbiome ( Wei et al, 1975 ; Kim et al, 2019 ). Shifts in the light/dark cycle causing chronic circadian misalignment resulted in a loss of colonic barrier function in mice ( Tran et al, 2021 ). Sleep deprived mice have lower melatonin concentrations in colonic tissue in addition to increased colonic abundance in Erysipelotrichales and Enterobacteriales , which may induce inflammation, and decreased Lactobacillales , which is a beneficial bacterium in the GIT ( Park et al, 2020 ).…”