Inflammatory Response by Ocular Surface Epithelia Upon Exposure to Prostaglandin Analogs

Abstract

Purpose: : Prostaglandin analogues (PGAs) are the most common treatment for glaucoma. Most PGA formulations, like travoprost and latanoprost, contain the preservative benzalkonium chloride (BAK). Travoprost Z is preserved with a new ionic buffered preservative system, sofZia. C-reactive protein (CRP), interleukins (IL)-1, 10 and 12 and tumor necrosis factor (TNF), have long been described as conventional biomarkers of inflammation. The purpose of this study was to evaluate the secondary inflammatory response to the ocular surface resulting from the potential toxicity of the PGAs utilizing enzyme linked immunosorbant assays (ELISAs) to quantify the resultant levels of the above mentioned biomarkers of inflammation in response to varying concentrations of BAK and/or H₂O₂.

Methods: : Human conjunctival (CCC: P61 HCK) and corneal epithelial (HCE: CEPI 17) cells at confluency were incubated with 100 uL of the commercial PGA formulations or their major components: travoprost Z 0.004%; travoprost 0.004% with BAK 0.015%; latanoprost 0.005% with BAK 0.02%; as well as pure cell media and lipopolysaccharide (LPS) at 100 and 10 ng/mL as controls. After 1 hour, the solution was removed for CRP, IL-1, IL-10, IL12, TNF and H₂O₂ quantification via enzyme-linked immunosorbent assays (ELISAs) giving results in pg/mL (mg/mL for H₂O₂).As cytokine elaboration requires longer than 1 hour, an experiment was run in which the testing solutions were removed after 1 hour and replaced with pure cell media for an additional 23 hours.

Results: : Travoprost Z (0.004%) elicited the lowest inflammatory response, latanoprost 0.005% BAK 0.02% the greatest. Of the components studied, the preservative appeared to induce the majority (approx 70%) of the response. In decreasing order the mediators elaborated were: TNF > IL-1>IL-12 > CRP > IL-10. CCC elaborated only slightly more than HCE. LPS at either concentration incubated for the 1 hour with an additional 23 hours of elaboration time induced the elaboration of large amounts of IL-1 (approx 618 pg/mL) and TNF (approx 12.7 ug/mL). Generally, HCE cells were more sensitive than the conjunctival.

Conclusions: : All prostaglandin analogs evoked an increase of inflammatory biomarkers in a cell culture model of surface epithelium. The addition of benzalkonium chloride (BAK) increased the response. latanoprost > travoprost > travoprost Z.

Keywords: inflammation • drug toxicity/drug effects • cornea: epithelium