Effect of multipurpose solutions on cell morphology and cytokine production by corneal epithelial cells

We sought to determine whether human corneal limbal epithelial cells (HCLE) differ in their physiological response and production of inflammatory mediators during exposure to two multipurpose disinfecting solutions that differ in only four excipients.

HCLE were exposed to dilutions (1%-20%) of OPTI-FREE Express and OPTI-FREE RepleniSH for 2, 6, or 18 h. Cell numbers were measured using CyQuant and metabolic activity assays. Morphology, viability, and apoptotic changes were examined by confocal microscopy after staining with Calcein AM/propidium iodide or Hoechst 33,342/propidiun iodide/YO-PRO-1. Cytokine responses and arachidonic acid metabolites were examined by enzyme-linked immunosorbent assay.

OPTI-FREE Express showed greater reductions in corneal cell metabolic activity (up to 3-fold) than OPTI-FREE RepleniSH over 18 h. Cells exposed to OPTI-FREE Express were highly vacuolated, whereas those exposed to OPTI-FREE RepleniSH had morphology consistent with a presumed apoptotic response. OPTI-FREE Express elicited higher levels of interleukin (IL)-6 (maximum 4225 ± 300 pg/mL) and IL-8 (maximum 1094 ± 250 pg/mL) from cells than OPTI-FREE RepleniSH (maximum of 1717 ± 225 pg/mL and 930 ± 300 pg/mL, respectively) at all concentrations tested after 18 h. HCLE did not produce leukotriene B4 or prostaglandin E2 on stimulation, and IL-1β was produced in low levels, but its production was not different between multipurpose disinfecting solution types.

The findings reported here are the first to describe the pattern of cytokine production produced in corneal epithelial cells in response to contact lens solutions. Alteration of only four excipients in the formulations had such effects on corneal epithelia; however, these differences do not explain differences in the incidences of corneal infiltrative events between these solutions. This might indicate that changes in the rates of infiltrative events result from interactions of the solutions with the contact lens surface, or directly with the corneal immune system, or as the result of gram-negative contamination of lens cases.