Purpose: Regulation of inflammation is critical for achieving favorable outcomes in wound healing. In this study, we determine the functional role and mechanism of action of IL-11, an immunomodulatory cytokine, in regulating inflammatory response at the ocular surface.
Methods: Corneal injury was induced by mechanical removal of the epithelium and anterior stroma using an AlgerBrush II. Transcript and protein levels of IL-11 in injured cornea were quantified using real-time PCR and ELISA analysis. Corneal inflammation was assessed by measuring frequencies of total CD45+ inflammatory cells, CD11b+Ly6G+ polymorphonuclear cells (neutrophils), and CD11b+Ly6G- mononuclear cells (macrophages, monocytes) at the ocular surface using flow cytometry. To assess the effect of IL-11 on innate immune cell function, cell activation marker and inflammatory cytokines including major histocompatibility complex (MHC) class II, myeloperoxidase (MPO), TNFα, and inducible nitric oxide synthase (iNOS) were measured following recombinant IL-11 treatment (1 µg/mL). Injured corneas were topically treated with IL-11 (1 µg/mL), and wound healing was evaluated using corneal fluorescein staining.
Results: Corneal injury resulted in increased levels of IL-11 in the cornea, particularly in the stroma. Neutrophils and CD11b+ mononuclear cells (macrophages, monocytes) substantially expressed IL-11 receptor. Interestingly, IL-11 significantly downregulated the activation of immune cells, as evidenced by the lower expression of MHC II and TNFα by CD11b+ mononuclear cells and lower levels of MPO by neutrophils. Topical administration of IL-11 to injured corneas led to faster wound healing and better retention of tissue architecture.
Conclusions: Our findings demonstrate IL-11 is a key modulator of ocular surface inflammation and provide novel evidence of IL-11 as a potential therapeutic to control inflammatory damage and accelerate wound repair following injury.