July 2007




Prevention of PCO through cyclooxygenase-2 inhibition




Using cyclooxygenase-2 (COX-2) inhibitors in vivo may be an effective technique in preventing posterior capsular opacification (PCO), according to a recent study in Molecular Vision.

Heather L. Chandler, B.Sc., College of Veterinary Medicine, The Ohio State University, Columbus, and her colleagues tested the COX-2 inhibitors on canine cataracts noting that extracapsular phacoemulsification is the most common surgical procedure in both human and veterinary ophthalmology.

The research team also wanted to determine if COX-2 was being upregulated when lens epithelial cells (LEC) underwent epithelial-mesenchymal transition (EMT)-like changes.

The study reported that EMT markers such as lumican, Snail, Slug and COX-2 were expressed in the LEC. In clinical samples of cataracts and PCO, there was an overexpression of COX-2 protein and mRNA. Also, Dr. Chandler noted that both rofecoxib and celecoxib were effective at inhibiting PCO formation in the study. “Prevention of PCO with the COX-2 inhibitors appeared to work through decreased migration and proliferation and increased apoptosis,” Dr. Chandler said in the study. “Neither of the drugs had a toxic effect on confluent LEC and appeared to inhibit PCO through pharmacologic action.”

Furthermore, the synthesis of PGE2 was inhibited in the capsules treated with COX-2 inhibitors. Following extracapsular phaco, the LEC that remained adhered to the lens capsule underwent EMT-like changes, proliferated and migrated across the posterior capsule causing PCO. This study shows that COX-2, a protein associated with EMT, is upregulated in canine cataracts and PCO, Dr. Chandler said. Inhibiting the enzyme activity effectively prevented EMT of the LEC in the ex vivo model of PCO through pharmacologic action and not acute toxicity. Therefore, Dr. Chandler and her team recommended that this could be a useful technique in preventing PCO in humans.

Source: Chandler HL, Barden CA, Lu P, et al. Molecular Vision 2007; 13:677-91. Reported by: EyeWorld News Service

Prevention of PCO through cyclooxygenase-2 inhibition Prevention of PCO through cyclooxygenase-2 inhibition
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