Phospholipase A₂Activity in Normal andStaphylococcus aureus-Infected Rabbit Eyes

Abstract

The decrease in PLA(2) activity in the rabbit eye with age or after sleep and its increase during sleep or with the progression of infection are consistent with its role as an innate host defense factor.

Staphylococcus aureus protein A induced inflammatory response in human corneal epithelial cells

“…Whereas the topical application of Pseudomonas aeruginosa to a scarified rabbit cornea results in keratitis, S. aureus does not elicit keratitis in scarified rabbit eyes. Several studies revealed that topical application of a large number of S. aureus to scarified rabbit cornea resulted in inflammation, but not actual infection since bacterial replication, a characteristic of bacterial keratitis, was not produced in these animal models [12]. Therefore, to date, the animal models of S. aureus keratitis have relied on intrastromal injection of log phase bacteria into the cornea to study the role of specific staphylococcal surface components in corneal virulence and in triggering host inflammation and defense.…”

sPLA2-IIa is an inflammatory mediator when the ocular surface is compromised

“…In normal subjects, the concentration of sPLA2-IIa in tears is 54.5+/-33.9 μg/ml, one of the highest levels of sPLA2-IIa reported in any normal human secretions (Saari et al, 2001). Since its bactericidal role has been well appreciated through direct catalytic activity of the enzyme on the gram-positive bacterial wall, the presence of sPLA2-IIa has been considered as an innate immune barrier of the ocular surface against microbial infection (Buckland et al, 2000; Girgis et al, 2003; Nevalainen et al, 2008; Qu et al, 1998). Accumulated evidence indicates that the non-catalytic activity of sPLA2-IIa also plays an important role in modulating the pathogenesis of many inflammatory-related diseases and cancers (Adibhatla et al, 2007; 2008; Fijneman and Cormier, 2008; Lambeau and Gelb, 2008; Menschikowski, et al 2006; 2008).…”

Host defense against bacterial keratitis

“…5 To analyze the effects of age on PLA 2 activity, pooled tears were collected from young rabbits (n = 4; 10 weeks old) at four-week intervals, up to 32 weeks of age. Tears collected from young rabbits demonstrated high PLA 2 activity, as demonstrated by the radioactive arachidonic acid liberated (Fig.…”

“…4,5 Briefly, radiolabeled bacteria were incubated with either tears or aqueous humor (or a 1 : 5 dilution thereof in Tris-HCl buffer, pH 7.5), with 2 mM CaCl 2 added. The mixtures were incubated for 30 min at 33 °C.…”