Dimethyl itaconate attenuates dextran sulfate sodium-induced ulcerative colitis in BALB/c mice: investigations on the TXNIP/NLRP3 inflammasome signaling pathway.

BACKGROUND: Ulcerative colitis (UC) involves recurrent colonic mucosal inflammation and impaired epithelial repair. Current therapies are limited due to safety concerns. The TXNIP-NLRP3 inflammasome axis serves as a critical link between oxidative stress and inflammation in UC. The present study evaluated the protective role of dimethyl itaconate (DMI), a cell-permeable itaconate derivative, in a chronic dextran sulfate sodium (DSS)-induced ulcerative colitis model with verapamil as a positive control.

METHODOLOGY: Chronic colitis was induced in male BALB/c mice with repeated cycles of 3% DSS. Experimental groups included control, DSS, DSS + DMI (25, 50, or 100 mg/kg), DSS + verapamil (10 mg/kg), and DMI/verapamil per se. Disease indices, histopathology, oxidative stress markers (MPO, MDA, nitrite, SOD2, ROS), barrier function (serum FITC-dextran, goblet cells), systemic inflammation (LPS, TNF-α, IL-1β), haematological parameters (CBC, serum albumin), ultrastructure analysis (HR-TEM), and expression of TXNIP-NLRP3 axis proteins were evaluated. Network pharmacology identified potential targets of DMI using SwissTargetPrediction, PharmMapper, RGD, CTD, and STRING. The integrated drug-target-disease network was constructed and analysed in Cytoscape 3.7.2. Molecular docking in ArgusLab predicted interactions and binding scores of DMI with TXNIP and NLRP3.

RESULTS: DSS exposure increased oxidative stress, inflammation, barrier dysfunction, and expression of TXNIP, NLRP3 inflammasome-related proteins (ASC, caspase-1, cleaved caspase-1, IL-1β, IL-18), TLR-4, LBP, TNF-α, SOD2, and LPS, while decreasing IL-10 expression. Low (25 mg/kg) and mid dose (50 mg/kg) of DMI showed consistent protection in the majority of the evaluated end-points. DMI significantly reduced disease severity, restored colonic architecture as well as barrier integrity, attenuated oxidative stress, inflammation, and fibrosis, and modulated protein expressions, with effects comparable to verapamil. The high dose of DMI (100 mg/kg) did not provide significant functional recovery in different endpoints of evaluation. Network analysis identified TLR4 as a central target, with enrichment of NOD-like receptor, Toll-like receptor, PI3K-Akt, HIF-1, and NF-κB pathways, which suggest that DMI potentially acts through multiple interconnected mechanisms to regulate inflammatory responses in UC. Molecular docking predicted moderate binding of DMI with TXNIP (-6.44 kcal/mol) and NLRP3 (-7.28 kcal/mol).

CONCLUSION: DMI significantly protects against chronic DSS-induced colitis by modulating TXNIP-NLRP3 inflammasome signalling, reducing oxidative stress, and restoring epithelial and systemic homeostasis. These findings provide proof-of-concept that DMI can mitigate experimental colitis severity and limit disease progression in BALB/c mice.