RIPK3-Mediated Necroptosis Drives Macrophage Infiltration and Corneal Neovascularization After Alkali Burn.

Purpose: To reveal the role of receptor-interacting protein kinase 3 (RIPK3) in regulating macrophage inflammation and corneal neovascularization (CoNV) induced by alkali burn.

Methods: A corneal alkali burn (AB) model was established in C57BL/6J (wild-type) and RIPK3fl/flCx3cr1+/cre (RIPK3-/-, RIPK3 knockout [KO]) mice using sodium hydroxide. Anterior segment optical coherence tomography and hematoxylin and eosin staining were used to evaluate the impact of RIPK3 on corneal edema and morphology. CoNV was detected by slit-lamp microscopy and whole-mount immunofluorescence staining of cornea. Corneal macrophage and necroptotic cell death was analyzed through immunofluorescence staining and propidium iodide (PI) staining. Activation of the necroptosis pathway was examined after corneal AB by western blot.

Results: Necroptosis-related proteins RIPK1, RIPK3, and mixed lineage kinase domain-like (MLKL) were upregulated and activated following corneal AB. Among these, RIPK3 demonstrated the most pronounced increase. Notably, the elevated level of RIPK3 was prominently colocalized with the infiltrating F4/80+ macrophages. RIPK3 KO significantly alleviated corneal edema and morphology defects. Additionally, as the corneal morphological defects progressed, macrophages became activated, and CoNV and lymphangiogenesis (LyG) were enhanced. RIPK3 KO markedly reduced AB-induced macrophage accumulation, as well as CoNV and LyG. RIPK3 KO mice also showed a meaningful decrease in PI+ necroptotic cells. Mechanistically, AB-induced necroptosis stimulated the expression of MLKL and fibroblast growth factor 2 (FGF2), whereas RIPK3 deficiency decreased their expression.

Conclusions: This study revealed that RIPK3-mediated necroptosis drives macrophage inflammation and CoNV. Targeting RIPK3 could effectively suppress these responses by inhibiting the MLKL/FGF2 pathway, making it a promising therapeutic strategy for corneal AB.