VGX-1027 is an isozaxoline compound that has recently been found to primarily target the function of murine macrophages but not of T cells, inhibiting secretion of tumor necrosis factor (TNF)-alpha in response to different Toll-like receptor agonists in vitro and in vivo. The well-defined role of innate immunity in inflammatory bowel diseases prompted us to consider the use of VGX-1027 in these diseases leading us to in vitro and in vivo test the drug in related experimental conditions. These consist, respectively, of the proliferation assay of CD4+CD25- T cells to enterobacteria, and the acute inflammatory colitis induced in mice by intracolonic challenge with dinitrobenzene sulfonic acid. The data from the two sets of experiments revealed that VGX-1027 inhibited both proliferation of enterobacterial antigen-reactive CD4+CD25- T cells in vitro and the development of clinical and histological signs of colitis in vivo. The beneficial effect in this model was associated with reduced colonic production of proinflammatory cytokines such as interleukin (IL)-1beta, TNF-alpha, IL-12p70 and interferon (IFN)-gamma and lower content of nuclear factor (NF)-kappaB (p65). These findings seem to warrant investigations of VGX-1027 for use in human.