Interferon Regulatory Factor 3 as a Mediator and Therapeutic Target in Innate Immune-Driven Corneal Stromal...

Interferon regulatory factor 3 (IRF3) is classically recognized for antiviral immunity, yet emerging evidence implicates it in sterile inflammation. This study investigated whether IRF3 regulates macrophage-stromal signaling driving corneal pathology and evaluated the therapeutic potential of targeting IRF3.

In vitro assays utilized human macrophages stimulated with lipopolysaccharide (LPS) and interferon-γ (IFNγ) to generate an inflammatory macrophage population (Mϕ-LPS/IFNγ cells), along with primary human corneal stromal fibroblasts (HCFs) stimulated with LPS. IRF3 was silenced by small interfering RNA (siRNA), and inflammatory mediators and toll-like receptor 4 (TLR4)/MyD88 transcripts were quantified. Macrophage-HCF interactions were assessed in Transwell cocultures. In vivo, Irf3-/- and wild-type mice underwent corneal epithelial debridement followed by topical LPS to evaluate corneal opacity, fibrotic markers, cytokine expression, and myeloid-cell subsets. Piceatannol, a stilbenoid compound known to inhibit IRF3, was tested in vitro and as topical eye drops.

IRF3 expression was upregulated in both macrophages and HCFs under inflammatory conditions. Silencing IRF3 significantly reduced inflammatory cytokines, including CXCL10, and decreased TLR4-associated transcripts in HCFs. In cocultures, IRF3-silenced macrophages partially attenuated HCF activation. In vivo, Irf3 deficiency markedly reduced LPS-induced corneal opacity, stromal inflammatory transcripts, monocyte recruitment, and macrophage-associated markers. Piceatannol suppressed IRF3-dependent inflammatory responses in vitro and, when applied topically, reduced corneal Irf3 expression and myeloid/inflammatory signatures.

IRF3 is a pivotal regulator of innate immune-driven stromal inflammation and opacity. Both genetic and pharmacologic inhibition of IRF3 attenuated cytokine and myeloid responses, suggesting that targeting IRF3, potentially via piceatannol (PIC), offers a therapeutic strategy for preserving corneal transparency.