Fenofibrate ameliorates ocular surface inflammation in diabetic keratopathy

Purpose: To investigate the efficacy of oral fenofibrate in the amelioration of ocular surface inflammation in diabetes mellitus (DM). Methods: In this open-label interventional study, 41 participants with type 2 DM received oral fenofibrate for 30 days. Forty age-matched healthy controls were recruited. Ocular surface objective and subjective assessment, in-vivo confocal microscopy (IVCM) imaging and quantification for corneal dendritic cells (DCs), epithelium and neuromas were performed. Tear inflammatory markers and proteomics were analyzed with enzyme-linked immunosorbent assay (ELISA) and Data Independent Acquisition experiments before and after treatment. Results: Oral fenofibrate treatment significantly improved tear film breakup time (p = 0.004), corneal staining evaluated with National Eye Institute-Corneal Fluorescein Staining scores (p = 0.005), and ocular surface symptoms assessed with the Ocular Surface Disease Index scores (p = 0.003), in DM patients. On IVCM, fenofibrate significantly reduced mean DC area (p = 0.01) and mean DC density (p = 0.02), while increasing mean DC elongation (p = 0.004) and length (p = 0.01), suggesting less DC activities. Fenofibrate also significantly increased corneal epithelial cell density (p = 0.04). 192 tear proteins were significantly altered after treatment. Fenofibrate significantly up-regulated the expression of anti-inflammatory interleukin-1 receptor antagonist, while significantly reduced the concentrations of pro-inflammatory and inflammatory proteins, including tumour necrosis factor α, nuclear factor kappa B, complement 4 B, cytochrome B5 Type A, and cytochrome B5 Type B (all p < 0.05) in tears, via regulation of tricarboxylic acid cycle, oxidative phosphorylation and liver X receptor/retinoid X receptor activation. Conclusion: This first clinical trial demonstrated that oral fenofibrate ameliorates diabetic ocular surface inflammation, providing a novel therapeutic option for diabetic keratopathy.