Circadian pharmacological effects of berberine on chronic colitis in mice: Role of the clock component Rev-erb alpha

摘要

Berberine, initially isolated from Rhizoma Coptidis (Huanglian in Chinese), is a drug used to treat gastrointestinal disorders such as colitis. Here we uncovered a time-varying berberine effect on chronic colitis in mice, and investigated a potential role of the clock protein Rev-erb alpha in this timing effect. Berberine activity toward Rev-erb alpha was determined by luciferase reporter, Gal4-cotransfection assay and target gene expression analyses. Chronic colitis was induced by feeding mice with dextran sulfate sodium in drinking water. Colitis severity and pharmacological effects of berberine were assessed by measuring myeloperoxidase and malondialdehyde activities as well as the levels of inflammatory factors (IL-1 beta, IL-6, IL-18 and Ccl2). Berberine significantly inhibited Bmal1 (-2000/+100 bp)- and Nlrp3 (-1310/+100 bp)-Luc reporter activities, and dose-dependently decreased cellular expressions of both Bmal1 and Nlrp3. Also, it enhanced the transcriptional repressor activity of Rev-erb alpha in the Gal4 chimeric assay. These data indicated berberine as a Rev-erb alpha agonist. As expected, berberine attenuated inflammatory responses in BMDMs (bone marrow-derived macrophages) and in colitis mice. However, the anti-inflammatory effects of berberine were lost in BMDMs derived from Rev-erb alpha-deficient mice. Furthermore, chronic colitis displayed a diurnal rhythmicity in disease severity and its diurnal pattern was in an opposite phase to that of Rev-erb alpha expression, supporting a direct control of colitis by Rev-erb alpha. Moreover, berberine effects on chronic colitis were dosing time-dependent. ZT10 dosing generated a better treatment outcome compared to ZT2. This was because colitis was less severe and Rev-erb alpha expression was much higher at ZT10 than at ZT2. In conclusion, circadian pharmacological effects of berberine on chronic colitis were mainly contributed by diurnal rhythms of both disease severity and Rev-erb alpha (as a drug target). The findings may have implications for chronotherapeutic practice on colitis or related diseases.