Reactive oxygen species activate and tetracyclines inhibit rat osteoblast collagenase

Abstract

Recent studies have demonstrated that tetracyclines (TCs) scavenge reactive oxygen species (ROS). Hypochlorous acid (HOCl), an ROS produced by neutrophils, has been shown to activate neutrophil procollagenase. The objective of the present study was to determine whether (1) HOCl also activated osteoblast procollagenase and (2) TCs inhibited this enzyme in the presence of HOCl. HOCl (5 microM) activated the proenzyme approximately sixfold (P < 0.01) from the medium of PTH-treated UMR-106-01 osteoblastic osteosarcoma cells as determined by functional collagenase assay (3H-methyl-labeled collagen substrate). Doxycycline (50-400 microM) and chemically modified tetracycline, CMT-1 (100-400 microM), significantly inhibited collagenase activity 50-90% and 40-80%, respectively, in the presence of 5 microM HOCl. Concentrations of 6-25 microM doxycycline and 10-50 microM CMT-1 had no significant effect. Furthermore, an excess concentration of cation (50 mM CaCl2 or 50 microM ZnCl2) added to the incubation mixtures containing either doxycycline or CMT-1 did not restore collagenase activity, as demonstrated by SDS-PAGE-fluorography. These data suggested that TCs reduced available HOCl and thus prevented the hypochlorous acid conversion of the osteoblast proenzyme to active collagenase. TCs may have therapeutic potential in the treatment of periodontitis and other diseases by several mechanisms that inhibit pathologic collagen breakdown.

Antioxidants but not Doxycycline Treatments Restore Depressed Beta-Adrenergic Responses of the Heart in Diabetic Rats

“…release mechanisms in diabetic cardiomyocytes. Previous studies, which are supporting our present data, have also shown that doxycycline has some ability to inhibit ROS [32,33]. Ramamurthy et al [33] showed that 50-100 lM tetracyclines were necessary to prevent hypochlorite activation of pro-collagenase, although less than 30 lM is required to inhibit MMP activity.…”

“…Previous studies, which are supporting our present data, have also shown that doxycycline has some ability to inhibit ROS [32,33]. Ramamurthy et al [33] showed that 50-100 lM tetracyclines were necessary to prevent hypochlorite activation of pro-collagenase, although less than 30 lM is required to inhibit MMP activity. Akamatsu et al [32] showed that 2 lM doxycycline would inhibit in vitro systems generating superoxide, hydroxyl, or hydrogen peroxide by 0, 16, and 22%, respectively.…”

Effects of a timely therapy with doxycycline on the left ventricular remodeling according to the pre-procedural TIMI flow grade in patients with ST-elevation acute myocardial infarction

“…Previous studies have also shown that doxycycline has some ability to inhibit reactive oxygen species (ROS) [24]. Although we cannot exclude the possibility that doxycycline may have other protective effects because of its reported pleiotropic actions including inhibition of proinflammatory cytokines and ROS, it is plausible that, to the plasma concentration achievable with the dose of doxycycline used in our study [13], MMP inhibition, as opposed to ROS scavenging, may be the main mechanism of its protective action [25].…”

Long-Term Doxycycline Is More Effective Than Atenolol to Prevent Thoracic Aortic Aneurysm in Marfan Syndrome Through the Inhibition of Matrix Metalloproteinase-2 and -9

“…30 The inhibition of the enzymatic activity of MMPs could be attributable to doxycycline binding to the zinc/calcium at their catalytic sites. 29 In addition, doxycycline could inhibit the activation of pro-MMPs by suppressing oxidative stress 26,38 and by promoting proteolysis of pro-MMPs into enzymatically inactive fragments. 29 The reduction in MMP protein expression could also result from the decreased steady-state levels of MMP mRNA.…”