Gene expression of down-regulation of lysyl oxidases family in keratoconus corneal fibroblasts induced by combination of mechanical stretching and prostaglandin E 2

Abstract
To examine the effects of mechanical stretching combined with prostaglandin E2 (PGE2) on the gene expression of lysyl oxidases (LOXs) in keratoconus, we treated cultured corneal fibroblasts from both healthy human corneas and keratoconus patient corneas with PGE2 and/or cyclic stretch (12% elongation, 0.1 Hz, 12 hours). Real-time fluorescent quantitative polymerase chain reaction was used to analyze LOX gene expression.

Our findings revealed that LOX gene expression was significantly lower in the keratoconus group compared to the healthy group. In the healthy group, 12% mechanical stretching alone upregulated the expression of LOXL-2 and LOXL-4, whereas in the keratoconus group, it downregulated LOXL-3 and LOXL-4. When 12% stretching was combined with PGE2, LOXL-4 expression was downregulated in the healthy group, while all LOXs except LOXL-1 were downregulated in the keratoconus group.

These results suggest that the combination of mechanical stretching and PGE2 leads to reduced LOX expression in keratoconus. Lower LOX levels may contribute to impaired collagen cross-linking, weakening cohesion between collagen fibrils and promoting slippage of collagen lamellae, ultimately compromising corneal structural stability. This mechanism may play a role in the development of keratoconus. Investigating the effects of mechanical stretching and inflammatory factors on LOX expression in this study provides insights into the underlying pathogenesis of keratoconus and may offer valuable guidance for its prevention and treatment.