5‐Methoxytryptophan Alleviates Dextran Sulfate Sodium‐Induced Colitis by Inhibiting the Intestinal Epithelial Damage and Inflammatory Response.

Background. Colitis is a refractory intestinal inflammatory disease significantly affecting the quality of a patient's life and increasing the risk of exacerbation. The primary factors leading to colitis encompass infections, insufficient blood flow, and the buildup of collagen as well as white blood cells. Among various available therapeutics, 5‐methoxytryptophan (5‐MTP) has emerged as one of the protectants by inhibiting inflammatory damage. Nonetheless, there is no report on the role of 5‐MTP in the treatment of colitis. Materials and Methods. To verify the anti‐inflammatory effect of 5‐MTP in vivo, we first constructed mouse model with dextran sulfate sodium‐induced colitis. Furthermore, the macrophage infiltration and release of inflammatory factors through western blot (WB) and hematoxylin–eosin staining analyses were examined. Intestinal epithelial cell tight junction damage and apoptosis were investigated by WB analysis, immunofluorescence, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Finally, we examined the generation of cellular inflammation and analyzed the influence of 5‐MTP on M1 polarization at the cellular level. Results. This study initially confirmed that 5‐MTP possessed an excellent therapeutic effect on colitis. 5‐MTP inhibits macrophage infiltration and the generation of inflammatory factors. In addition to its effects on immune cells, 5‐MTP significantly inhibits intestinal epithelial cell tight junction damage and apoptosis in vivo. Moreover, it inhibits inflammation and M1 polarization response in vitro. Conclusion. 5‐MTP counteracts excessive inflammation, thereby preventing intestinal epithelial tight junction damage. In addition, inhibition of apoptosis suggests that 5‐MTP may be a potential therapeutic agent for colitis. [ABSTRACT FROM AUTHOR]