Specific MSI2 deletion maintains intestinal barrier integrity by down-regulating ILC3s-derived IL-17 a in mice with colitis.

BACKGROUND

Ulcerative colitis (UC) is an inflammatory bowel disease with an unknown cause. Previous studies have shown that Group 3 innate lymphoid cells (ILC3s) are crucial for maintaining intestinal mucosal immune homeostasis by producing key cytokines such as IL-22 and IL-17 A. While the RNA-binding protein Musashi-2 (MSI2) is recognized as essential for promoting intestinal epithelial regeneration post-injury, its impact on immune regulation remains unclear. Therefore, we aim to investigate the protective mechanisms associated with ILC3s-specific MSI2 deletion in a mouse model of ulcerative colitis.

METHODS

Dextran sulfate sodium (DSS) was used to induce a mouse colitis model. Colitis severity was evaluated through weight loss, diarrhea, fecal traits, colon length, and pathological scoring. Transcriptome sequencing was utilized to identify differentially expressed genes in colon tissues. Flow cytometry was employed to measure the quantity and functionality of ILC3s. Western blot was conducted to analyze protein expression, while real-time polymerase chain reaction and enzyme-linked immunosorbent assay were employed to quantify inflammatory factors. Additionally, immunofluorescence, AB-PAS staining, and immunohistochemistry were employed to evaluate the integrity of the intestinal barrier.

RESULTS

Following DSS treatment, colon damage was milder in Msi2∆Rorc mice than in Msi2fl/fl mice. Transcriptomic analysis revealed the down-regulation of cytokines and pro-inflammatory factors in the colon tissue of Msi2∆Rorc mice. Flow cytometry showed that specific deletion of MSI2 reduced the infiltration of ILC3s in the intestinal lamina propria of Msi2∆Rorc mice and decreased IL-17 A production. The reduction of IL-17 A-mediated immune responses lessened inflammatory damage to the intestinal barrier, thereby reducing colitis severity.

CONCLUSIONS

Specific deletion of MSI2 alleviates DSS-induced colitis in mice by reducing ILC3s infiltration and IL-17 A secretion in the lamina propria of the colon. This decrease in inflammatory mediators and cell infiltration dampens the inflammatory response in the intestinal mucosa, helping to maintain the integrity of the intestinal barrier in mice with colitis. These findings enhance our understanding of UC pathogenesis and offer novel avenues for clinical diagnosis and treatment.