MedicalResearch: What are the main findings of the study?
Dr. Voigt: We found that chronic circadian rhythm disruption has no effect on the intestinal microbiota when mice are fed a standard chow diet but when combined with a high-fat, high-sugar diet circadian rhythm disruption results in intestinal dysbiosis and an increase in pro-inflammatory bacteria.
MedicalResearch: Were any of the findings unexpected?
Dr. Voigt: These results are in line with previous reports from our lab (and others) demonstrating that circadian rhythm disruption by itself is often not sufficient to induce a significant biological impact; however, when combined with a secondary insult (e.g., environmental or genetic factors) the detrimental effects of circadian rhythm disruption become apparent.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Voigt: The findings of our study support a “second hit hypothesis” whereby circadian rhythm disruption when combined with a secondary insult, poor lifestyle factors or a genetic predisposition, may negatively impact health. Circadian rhythm disruption is a prevalent feature of modern day society. Individuals with chronic circadian rhythm disruption including shift workers including doctors, nurses, firefighters, police officers, flight crews, etc as well as individuals who experience “social jet lag” (maintaining a different sleep/wake cycle and eating patterns during the weekend resulting from staying up late and/or sleeping in on the weekends) may be at higher risk of developing inflammatory-mediated diseases. There is a critical interplay between intestinal epithelial cells and the luminal contents of the intestine and disruption of the intestinal microbiota (intestinal dysbiosis) can negatively impact the integrity of the intestinal wall which provides a barrier separating luminal contents from the systemic circulation. Disruption of this barrier promotes systemic inflammation and end organ damage. As a first step to maintain health, individuals should try to maintain normal sleep/wake cycles and eating patterns. If this is not possible due to occupational or other factors, then individuals should try to minimize other lifestyle factors that may promote disease (e.g., poor eating habits, lack of exercise).
Finally, inclusion of prebiotics and/or probiotics in the diet may have mitigate some of the deleterious effects of circadian rhythm disruption on the intestinal microbiota and prevent the pro-inflammatory cascade that can result from intestinal dysbiosis.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Voigt: Future studies will need to evaluate the functional consequence of circadian rhythm disruption-mediated dysbiosis including metabolomics and the effect on diseases known to be promoted/exacerbated by inflammation.