Innate Immunity Biomarkers for Early Detection of Keratoconus

Purpose: To compare toll-like receptors 2 (TLR2) and 4 (TLR4) expression in cells of corneal and conjunctival epithelium between unilateral KC patients and control subjects. Methods: Prospective cross-sectional case-control study, including 50 unilateral KC patients and 20 control subjects. TLR2 and TLR4 expression was measured with flow cytometry. Results: Mean expression of TLR2 and TLR4, in corneal and conjunctival cells, was significantly higher in KC than in subclinical and control groups (all p < 0.0001). TLR2 expression in corneal epithelial cells can predict with the highest sensitivity and specificity the probability of KC existence compared to a control (area under the curve 0.995, 95% CI: 0.987-1.000; p < 0.0001). Corneal TLR2 expression also has a predictive capacity to discriminate between subclinical KC and controls (area under the curve 0.989, 95% CI: 0.975-1.000; p < 0.0001). Conclusions: TLR2 and TLR4 expression in corneal and conjunctival epithelial cells may constitute predictive biomarkers for the early detection of KC.