Therapeutic Efficacy of Rapamycin in an Experimental Mouse Model of Corneal Alkali Burn

Corneal alkali burn induces severe inflammation and tissue damage, leading to loss of corneal transparency and vision impairment. In this study, we evaluated the therapeutic potential of rapamycin (RAPA) compared with cyclosporine A (CsA) in a mouse model of corneal alkali burn, focusing on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-mediated inflammatory signaling and its impact on corneal wound healing and repair. Notably, RAPA robustly suppressed NF-κB activation, reduced infiltration of F4/80 macrophages and MPO neutrophils, and downregulated pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. RAPA also markedly inhibited corneal neovascularization, as evidenced by decreased VEGF expression, reduced CD31 vessel formation, and suppression of Ang-2. RAPA substantially inhibited pathological fibrotic remodeling by reducing TGF-β1 expression, attenuating myofibroblast activation (α-SMA), decreasing collagen III deposition, and modulating matrix remodeling through suppression of MMP-9. Crucially, RAPA preserved epithelial barrier integrity by maintaining occludin expression, supported proper epithelial differentiation through sustained expression of CK12, and enhanced mucin layer stability by increasing MUC1 expression. It also restored tear production, reduced apoptotic cell death (TUNEL), and decreased dysregulated epithelial proliferation (Ki67). In conclusion, RAPA showed superior efficacy compared with CsA, primarily by enhancing corneal wound healing and facilitating structural and functional outcomes in the burned cornea. These findings underscore RAPA as a promising therapeutic candidate for ocular surface repair and vision restoration in extensive corneal injury.