Effect of tetracyclines on collagenase activity in patients with recurrent aphthous ulcers

Human neutrophil-type (MMP-8) and fibroblast-type (MMP-1) interstitial collagenase, and their inhibition by tetracyclines in saliva from patients with recurrent aphthous ulcers (RAU) or aphthae, were studied by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and enzymological analyses. In the salivary specimens obtained from patients with aphthae, collagenase was found in endogenously active form and was predominantly of MMP-8 type. Topical rinsing treatment with chlortetracycline (Aureomycin) alleviated the discomfort caused by the lesions but did not reduce salivary collagenase amounts; however in vitro, doxycycline inhibited salivary collagenase totally.