Interleukin-1alpha downregulates extracellular-superoxide dismutase in human corneal keratoconus stromal cells

The purpose of this investigation was to elucidate the regulation of corneal extracellular superoxide dismutase (SOD3) synthesis in keratoconus. We compared the basal and cytokine-regulated SOD3 synthesis in cultured human stromal cells from keratoconus corneas to stromal cells from normal and bullous keratopathy corneas.

Keratocyte cultures were obtained from patients undergoing corneal transplantation for keratoconus and bullous keratopathy, and from healthy donor corneas. The cell lines obtained were cultured until near confluence and interleukin-1alpha, interleukin-6, transforming growth factor beta, or platelet derived growth factor were added to the media. The phenotypes of the cultured cells were assessed by immunocytochemical expression of alpha-smooth muscle actin and CD34. SOD3 protein contents were determined in the culture media with ELISA after 24, 48, 72, and 96 h.

Interleukin-1alpha had an inhibitory effect on SOD3 synthesis exclusively in the keratoconus cultures (p<0.01). Platelet derived growth factor induced a reduction in SOD3 synthesis in all groups (p<0.05).

Here, we demonstrate that cultured keratoconus stromal cells respond with a reduced SOD3 synthesis to interleukin-1alpha, which is not the case in corresponding normal or bullous keratopathy cells. Since interleukin-1alpha is upregulated in corneal trauma and inflammation, keratoconus corneas may muster an insufficient oxidative defense under such conditions.