Digoxin Attenuates Murine Experimental Colitis by Downregulating Th17-related Cytokines

Background: Digoxin, a cardiac glycoside used for the treatment of heart failure, was reported to inhibit the retinoid-related orphan receptor gamma t (RORgt) and attenuate the severity of experimental autoimmune encephalomyelitis and arthritis in mice. However, the effects of digoxin in a mice model of inflammatory bowel disease have not been elucidated. Methods: Colitis was induced in severe combined immunodeficiency mice by adoptive transfer of CD45RB(high) CD4(+) T cells. Digoxin or a vehicle was injected into mice with colitis intraperitoneally every other day and changes in body weight were evaluated. After 6 to 8 weeks, the treated mice were killed and evaluated for histological score, T-cell subset, and cytokine messenger RNA (mRNA) expression in the colonic tissue. Results: Wasting disease and histological damage were significantly attenuated in digoxin-treated mice with colitis compared with those in the vehicletreated mice. In addition, the mRNAs of Th17-related cytokines were downregulated, whereas those of interleukin-10 were upregulated in the colonic mucosa of digoxin-treated mice. However, unexpectedly, the mRNA expression level of tumor necrosis factor alpha did not decrease in the colonic mucosa of digoxin-treated mice with colitis. This observation suggests that digoxin may ameliorate colitis by a tumor necrosis factor alpha-independent pathway. Conclusions: This study has shown for the first time that treatment with digoxin can ameliorate murine experimental colitis. This finding suggests that the suppression of Th17 using reagents such as digoxin could be effective in treating Crohn's disease refractory to anti-tumor necrosis factor alpha therapy.