Mechanical corneal epithelium scraping and ethanol treatment up-regulate cytokine gene expression differently in rabbit cornea.

PURPOSE

To explore inflammation and wound healing in the rabbit eye following topical ethanol treatment or mechanical debridement.

METHODS

Seventy-six pigmented rabbit corneas were divided into four groups: mechanical group (n = 33), which received mechanical epithelial debridement; ethanol-30 (n = 18) and ethanol-60 groups (n = 18), which were treated with 20% ethanol for 30 and 60 seconds, respectively; and control group (n = 7), which remained untreated. Corneal epithelial and stromal keratocyte changes were examined with hematoxylin-eosin and terminal deoxynucleotidyltransferase-mediated dUPT nick end labeling (TUNEL) staining at 3 hours (day 0) and days 1, 2, 3, 5, and 7. Interleukin (IL)-1alpha, IL-8, monocyte chemotactic protein (MCP-1), and transforming growth factor (TGF)-beta1 expression were examined using real-time polymerase chain reaction.

RESULTS

Stromal keratocyte cell death was higher in the mechanical group on day 0 (P = .002) and in the ethanol-60 group on days 3, 5, and 7 (P < .05). Keratocyte cell death was more pronounced in the ethanol-60 group than in the ethanol-30 group. In the mechanical group, IL-1alpha, IL-8, and MCP-1 expression was up-regulated starting on day 0 (P < .05) and returned to baseline on day 5 to 7. TGF-beta1 expression was up-regulated in the mechanical group throughout the experiment (P < .05). In the ethanol-30 and ethanol-60 groups, IL-1alpha expression was up-regulated on day 0, IL-8 expression was slightly up-regulated on day 0, and MCP-1 and TGF-beta1 expression were not up-regulated.

CONCLUSIONS

Mechanical epithelial removal initially induces more keratocyte cell death, but deep stromal keratocyte death persists longer with ethanol treatment. In this rabbit model, mechanical epithelial removal upregulated inflammatory cytokines and TGF-beta1 gene expression more than ethanol treatment.