Abstract
Purpose::
Secretory phospholipaseA2-IIa (sPLA2-IIa) is constitutively expressed at high level in tears where it has been demonstrated to have powerful bactericidal effect. Yet, in multiple other conditions, most notably rheumatoid arthritis and septic shock, the same enzyme has been proven to be an important inflammatory mediator. Since sPLA2-IIa has been reported to be higher than normal in chronic blepharitis, contact lens intolerance and dry eye disease, the purpose of this study was to explore the potential role of the enzyme as an ocular inflammatory mediator.
Methods::
Human and rabbit corneal and conjunctival epithelial cells from primary cultures and the Chang human conjunctival epithelial cells were seed in 96 well plate and treated with human recombinant sPLA2-IIa, with or without TNFα, a known apoptisis inducer, which can stimulate inflammatory cytokine (including PGE2) production. After 24 hr the culture media were harvested and the PGE2 concentration was measured using a commercial enzymatic immunoassay kit.
Results::
sPLA2 significantly stimulate increased PGE2 production in all corneal and conjunctival cell types. In corneal cells, the increase was similar with that generated by TNFα, a known PGE2 inducer and the effects of both agents were additive. In conjunctival cells, sPLA2 had only a small effect in comparison with the effect of TNFα, but the combined application resulted in a strong synergistic response. .
Conclusions::
These findings suggest sPLA2-IIa may be an important inflammatory mediator in the ocular surface in particular in conditions where the cell surface is compromised. Further examination of a role of this abundant enzyme on chronic inflammation is warranted.
Keywords: inflammation • cornea: basic science • conjunctiva