Bryostatin-1 ameliorated experimental colitis in Il-10-/- Mice by protecting the intestinal barrier and limiting immune dysfunction.

Bryostatin-1 (Bry-1) has been proven to be effective and safe in clinical trials of a variety of immune-related diseases. However, little is known about its effect on Crohn's disease (CD). We aimed to investigate the impact of Bry-1 on CD-like colitis and determine the mechanism underlying this effect. In the present study, 15-week-old male Il-10-/- mice with spontaneous colitis were divided into positive control and Bry-1-treated (Bry-1, 30 μg/kg every other day, injected intraperitoneally for 4 weeks) groups. Age-matched, male wild-type (WT) mice were used as a negative control. The effects of Bry-1 on colitis, intestinal barrier function and T cell responses as well as the potential regulatory mechanisms were evaluated. We found that the systemic delivery of Bry-1 significantly ameliorated colitis in Il-10-/- mice, as demonstrated by decreases in the disease activity index (DAI), inflammatory score and proinflammatory mediator levels. The protective effects of Bry-1 on CD-like colitis included the maintenance of intestinal barrier integrity and the helper T cell (Th)/regulatory T cell (Treg) balance. These effects of Bry-1 may act in part through nuclear factor erythroid 2-related factor 2 (Nrf2) signalling activation and STAT3/4 signalling inhibition. The protective effect of Bry-1 on CD-like colitis suggests Bry-1 has therapeutic potential in human CD, particularly given the established clinical safety of Bry-1.