Low-dose interleukin-2 alleviates dextran sodium sulfate-induced colitis in mice by recovering intestinal integrity and inhibiting AKT-dependent pathways

Several phase 1/2 clinical trials showed that low-dose interleukin-2 (IL-2) treatment is a safe and effective strategy for the treatment of chronic graft-versus-host disease, hepatitis C virus-induced vasculitis, and type 1 diabetes. Ulcerative colitis (UC) is a chronic inflammatory condition of the colon that lacks satisfactory treatment. In this study, we aimed to determine the effects of low-dose IL-2 as a therapeutic for UC on dextran sulfate sodium (DSS)-induced colitis. Methods: Mice with DSS-induced colitis were intraperitoneally injected with low-dose IL-2. Survival, body weight, disease activity index, colon length, histopathological score, myeloperoxidase activity and inflammatory cytokine levels as well as intestinal barrier integrity were examined. Differential gene expression after low-dose IL-2 treatment was analyzed by RNA-sequencing. Results: Low-dose IL-2 significantly improved the symptoms of DSS-induced colitis in mice and attenuated pro-inflammatory cytokine production and immune cell infiltration. The most effective dose range of IL-2 was 16K-32K IU/day. Importantly, low-dose IL-2 was effective in ameliorating the disruption of epithelial barrier integrity in DSS-induced colitis tissues by restoring tight junction proteins and mucin production and suppressing apoptosis. The colon tissue of DSS-induced mice exposed to low-dose IL-2 mimic gene expression patterns in the colons of control mice. Furthermore, we identified the crucial role of the PI3K-AKT pathway in exerting the therapeutic effect of low-dose IL-2. Conclusions: The results of our study suggest that low-dose IL-2 has therapeutic effects on DSS-induced colitis and potential clinical value in treating UC.