Phospholipases A2 in normal human conjunctiva and from patients with primary open-angle glaucoma and exfoliation glaucoma

Background Chronic situations like long-term use of topical medications induces conjunctival inflammation and is also a significant risk factor for failure of filtering surgery. We evaluated conjuctival expression of group IIA secretory PLA 2 (sPLA 2 -IIA), group V secretory PLA 2 (sPLA 2 -V), calcium-independent PLA 2 (iPLA 2 ) and cytosolic PLA 2 (cPLA 2 ). Methods Samples were obtained from non-glaucomatous patients (control subjects), and patients with either primary open-angle glaucoma (POAG) or exfoliation glaucoma (ExG). All the glaucoma patients had been treated with antiglaucomatous medication, and underwent deep sclerectomy surgery. Antibodies against sPLA 2 -IIA, sPLA 2 -V, iPLA 2 and cPLA 2 were used for immunohistochemical staining of frozen tissue sections. Results In the human conjunctiva of non-glaucomatous patients, immunostaining of sPLA 2 -IIA, sPLA 2 -V or cPLA 2 was low and positively stained cells were mainly localized in the surface of the epithelium. In contrast, iPLA 2 was found to predominate in human normal conjunctiva and it demonstrated strong labeling throughout the epithelium. The stromal staining of iPLA 2 was weak. Expression of sPLA 2 -IIA was significantly increased in stromal fibers of patients with POAG or ExG. No changes were found in levels of sPLA 2 -V, iPLA 2 or cPLA 2 between the patient groups and controls. Conclusions These findings demonstrate that sPLA 2 -IIA, sPLA 2 -V, iPLA 2 and cPLA 2 are expressed in the conjunctiva of non-glaucomatous patients. In the epithelium, sPLA 2 -IIA, sPLA 2 -V, and cPLA 2 may participate in protection against risks caused by mechanical wear and tear stress whereas iPLA 2 may regulate remodeling and maintenance of membrane phospholipids. sPLA 2 -IIA may also have the important role in the degradation of bacteria. In conjunctival stroma of POAG and ExG patients, sPLA 2 -IIA may play a role in the development of scar tissue after glaucoma filtration surgery.