INHIBITION OF PSEUDOMONAL ULCERATION IN RABBIT CORNEAS BY A SYNTHETICMATRIX METALLOPROTEINASE INHIBITOR

Purpose, To evaluate the effect of the synthetic matrix metalloprotein ase inhibitor, Galardin, on proteases produced by Pseudomonas aerugino sa (PA) and on a rabbit model of Pseudomonas keratitis. Methods. Prote ase activities of culture broths from Pseudomonas strains PA-28 and W- 186 were characterized in vitro by gelatin zymography and by digestion of Azocasein in the presence and absence of Galardin and the serine p rotease inhibitor, aprotinin. In a noninfectious in vivo experiment, s terile PA culture broth from W-186 was injected intrastromally into ra bbit corneas that were treated topically with Galardin or vehicle, the n evaluated clinically and histologically. In an infectious in vivo ex periment, rabbit corneas were injected with washed PA-28, then treated topically with Galardin or vehicle and clinically scored. Results. Ge latin zymography of culture broth from W-186 and PA-28 detected two pr oteases that were both inhibited by Galardin. Galardin reduced the dig estion of Azocasein by both PA culture broths by 99%, whereas aprotini n did not significantly reduce the protease activity of PA-28 conditio ned broth. Intrastromal injection of sterile W-186 culture broth cause d rapid corneal destruction that was prevented by topical treatment wi th Galardin, Intrastromal injection of washed PA-28 bacteria resulted in progressive corneal melting that was significantly (P < 0.005) dela yed, but ultimately not prevented, by topical treatment with Galardin. Conclusions. Pseudomonal protease activity in culture broth consisted predominantly of metalloproteinases and were effectively inhibited by Galardin in vitro. Topical treatment with Galardin prevented destruct ion of rabbit corneas by bacterial products present in culture broth, and it delayed corneal destruction after injection of PA bacteria. Gal ardin may be a useful adjuvant when corneal destruction proceeds despi te prompt antibiotic treatment.