Itaconate derivative eye drops deploy anti-inflammatory effect in treating dry eye models

To investigate the therapeutic potential of 4-Octyl itaconic acid (4-OI), a derivative of the endogenous immunomodulator itaconate (ITA), as a safe and effective anti-inflammatory agent for the treatment of dry eye disease (DED). In vitro cytotoxicity and anti-inflammatory effects of 4-OI were evaluated in hyperosmotic human corneal epithelial cells (HCEC). An in vivo DED model was induced in C57BL/6 mice through environmental controlled chambers. Mice with DED were treated with PBS, 0.05% cyclosporine A (CsA) eye drops, 4-OI eye drops, or a single 4-OI intraperitoneal injection for 14 days. Corneal epithelial defects and tear secretion were assessed. The safety and underlying molecular mechanisms of topical 4-OI were evaluated using quantitative PCR (qPCR), Western blotting (WB), mRNA sequencing, TUNEL assay, and H&E staining. Statistical analyses were performed using independent sample t-tests and one-way ANOVA, with P < 0.05 considered statistically significant. Treatment with 4-OI eye drops significantly reduced corneal epithelial defects in DED mice ( P < 0.0001) compared to the DED control group. Tear secretion was also elevated in the 4-OI eye drop-treated groups. mRNA sequencing revealed significant downregulation of inflammatory pathways, including IL-1 receptor activity, TNF signaling, and IL-17 signaling, in the 2 mM 4-OI eye drop group. Molecular assays confirmed a marked reduction in the mRNA and protein expression of IL-1β, IL-17A, TNF-α, and NFKBIZ (IκBζ) in the corneas of 4-OI-treated mice. No significant corneal epithelial apoptosis or systemic toxicity was observed in the 4-OI-treated groups. The ITA derivative 4-OI demonstrates potential as a safe and effective therapeutic option for alleviating dry eye disease by suppressing ocular inflammation through the downregulation of IL-1, IL-17, and TNF signaling pathways. • First evidence: 4-OI eye drops reduce dry eye pathology in murine models. • Novel mechanism: 4-OI downregulates IL-1/IL-17/TNF pathways in cornea. • Topical 4-OI efficacy matches cyclosporine A, suggesting therapeutic potential. • 4-OI eye drops show excellent corneal safety and tolerability profile.