Recombinant Thrombomodulin Domain 1 Promotes Diabetic Corneal Wound Healing by Inhibiting HMGB1 Production and NLRP3 Inflammasome.

PURPOSE: To investigate the therapeutic potential of recombinant thrombomodulin domain 1 (rTMD1) in diabetic corneal wound healing and to elucidate its underlying mechanisms using in vitro and in vivo models. METHODS: rTMD1 was produced using the Pichia pastoris expression system and purified. Human corneal epithelial cells (HCECs) were cultured under normal glucose (NG) and high glucose (HG) conditions, with or without rTMD1 treatment. Wound healing rates were evaluated using a scratch assay. Diabetes was induced in C57BL/6 mice via streptozotocin (STZ) injections. Corneal wounds were created and treated with rTMD1 or PBS, and wound healing was assessed via fluorescein staining. Inflammatory markers, including HMGB1, TLR4, NLRP3, and IL-1β, were analyzed via quantitative PCR (qPCR), Western blot, and immunofluorescence staining. RESULTS: In vitro, HCECs treated with rTMD1 under HG conditions demonstrated a higher wound healing rate compared to untreated cells (p = 0.0049). In vivo, rTMD1 significantly enhanced corneal wound healing in diabetic mice, with faster wound closure compared to PBS-treated controls at 24 h (p = 0.005) and 48 h (p < 0.0001). rTMD1 treatment reduced the expression of HMGB1, TLR4, NLRP3, and IL-1β at both mRNA and protein levels, indicating suppression of inflammation. CONCLUSIONS: Topical application of rTMD1 promotes corneal epithelial wound healing in diabetic conditions by inhibiting HMGB1/TLR4/NLRP3-mediated inflammation. rTMD1 holds promise as a potential therapeutic agent for diabetic keratopathy, although further studies are needed to validate its clinical efficacy and safety.