Colonic inflammation modulates the intestinal circadian landscape.

Area of Science:

• Immunology
• Chronobiology
• Gastroenterology

Background:

• Inflammatory bowel disease (IBD) is a chronic condition with significant morbidity.
• The body's 24-hour circadian clock regulates immune responses, and its disruption is linked to inflammatory diseases.

Purpose of the Study:

• To investigate how acute colitis affects the intestinal circadian rhythm.
• To determine the consequences of disrupting the intestinal epithelial cell (IEC) clock on immune function during inflammation.

Main Methods:

• Induced acute colitis using dextran sulfate sodium.
• Examined circadian gene expression and cell populations in the inflamed colon.
• Utilized IEC-specific deletion of the core clock gene Bmal1 in mice.

Main Results:

• Inflamed colons showed weakened IEC clock function.
• New oscillations in colonic regulatory T cells emerged, with diurnal variations in activation.
• IEC-specific Bmal1 deletion altered rhythmic colonic gene expression and reduced gut microbiota rhythmicity, but did not affect colitis severity.

Conclusions:

• Colonic inflammation significantly impacts circadian processes.
• Circadian disruption in IECs alters immune cell dynamics and microbiota rhythmicity.
• Circadian-based therapeutic strategies could be beneficial for treating IBD.