TP-P1-Loaded Thermosensitive Hydrogel Attenuates Rheumatoid Arthritis in a Mouse Model via TLR4/NF-κB Pathway.

Purpose: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent inflammation, pain, and joint destruction, largely driven by inflammation and oxidative stress. This study explored the therapeutic potential of a thermosensitive hydrogel (TPTH) loaded with TP-P1, a derivative of triptolide, focusing on anti-inflammatory and antioxidant effects. Methods: A collagen-induced arthritis (CIA) model was established by dual immunization with type II collagen and Freund's adjuvant. Mice were randomized into control, model, dexamethasone (DEX), blank hydrogel, and TPTH groups. After 28 days of intra-articular treatment, arthritis severity was assessed by paw swelling, arthritis scores, and histopathology. Cytokines (IL-6, IL-1β, TNF-α) were measured by RT-qPCR and flow cytometry, oxidative stress markers (MDA, SOD, CAT, GSH) were determined, and TLR4/NF-κB expression was analyzed by Western blotting, immunohistochemistry, and RT-qPCR. Biosafety was evaluated via liver/kidney histology and plasma indices (ALT, AST, BUN, CRE). Results: TPTH treatment markedly alleviated arthritis symptoms, reducing paw swelling and scores (p < 0.0001). It downregulated inflammatory cytokines, improved antioxidant status (SOD, CAT, GSH) and decreased MDA. TPTH also suppressed TLR4 and NF-κB expression, indicating modulation of inflammatory signaling. Importantly, no obvious hepatic or renal toxicity was observed. Conclusion: TPTH significantly ameliorates inflammation and oxidative stress in CIA mice by modulating the TLR4/NF-κB pathway and shows promise as a safe and effective therapeutic strategy for RA.