Inflammatory Bowel Disease (IBD) is a chronic and frequently disabling inflammatory disorder of the intestine. New developments in IBD
therapy are primarily focused on
biologic treatments; however, they are both expensive and associated with significant side effects. Here, we provide the first preclinical evidence that
YunNan BaiYao (YNBY), a well-known traditional Chinese herbal remedy frequently used for treating
hemorrhages and
wounds, can effectively alleviate experimental
colitis.
Oral administration of YNBY in
drinking water significantly reduced the disease activities of both DSS- and TNBS-induced experimental
colitis. Mechanistic studies revealed that the effectiveness of YNBY was not due to an anti-bacterial function since YNBY had no effect on E. coli growth. Rather, it exhibited an anti-inflammatory or immunosuppressive function: In the DSS
colitis model, YNBY treatment decreased the levels of several pro-inflammatory
cytokines in colonic mucosa, including TNFα,
IL-12p40, and
IL-17. Similar
cytokine changes were also observed in mouse serum, suggesting that systemic changes in general reflect the changes in the affected colon. Significant down-regulation of
IL-12p40 and
IL-17, in addition to IFNγ, was also seen in TNBS-
colitis model. Another potential mechanism for the anti-inflammatory effects of YNBY involves the selective suppression of pro-inflammatory immune cells: YNBY effectively suppressed the growth of multiple T- and B-lymphocytes, including Molt-4, Jurkat, and EBV-transformed human B-lymphocytes, more potently than 6-mecaptopurine (6-MP) and
5-aminosalicylic acid (5-ASA), two of the most commonly used first-line drugs in IBD
therapy. In sharp contrast, YNBY exhibited no cytotoxicity to colonic epithelial cells (Caco-2 cells), even at the concentration 10-fold higher than that used in the lymphocyte model; and instead promoted cell spreading and wound healing. These results strongly suggest that YNBY not only has effective anti-inflammatory properties through suppressing lymphocyte growth and pro-inflammatory
cytokine expression, but also can promote intestinal epithelial wound-healing and repair. Therefore, YNBY demonstrates strong potential as an alternative
herbal therapy for IBD.