In Vivo Collagen Turnover Following Experimental Balloon Angioplasty Injury and the Role of Matrix Metalloproteinases

Abstract

Extracellular matrix formation is the major component of the restenosis lesion that develops after balloon angioplasty. Although ex vivo studies have shown that the synthesis of collagen is stimulated early after balloon angioplasty, there is a delay in accumulation in the vessel wall. The objectives of this study were to assess collagen turnover and its possible regulation by matrix metalloproteinases (MMPs) in a double-injury iliac artery rabbit model of restenosis. Rabbits were killed at four time points (immediately and at 1, 4, and 12 weeks) after balloon angioplasty. In vivo collagen synthesis and collagen degradation were measured after a 24-hour incubation with [14C]proline. Arterial extracts were also run on gelatin zymograms to determine MMP (gelatinase) activity. Collagen turnover studies were repeated in a group of 1-week postangioplasty rabbits that were treated with daily subcutaneous injections of either a nonspecific MMP inhibitor, GM6001 (100 mg/kg per day), or placebo. Collagen synthesis and degradation showed similar temporal profiles, with significant increases in the balloon-injured iliac arteries compared with control nondilated contralateral iliac arteries immediately after angioplasty and at 1 and 4 weeks. Peak collagen synthesis and degradation occurred at 1 week and were increased (approximately four and three times control values, respectively). Gelatin zymography was consistent with the biochemical data by showing an increase of a 72-kD gelatinase (MMP-2) in the balloon-injured side immediately after the second injury, peaking at 1 week, and still detectable at 4 and 12 weeks (although at lower levels). In balloon-injured arteries, the MMP inhibitor reduced both collagen synthesis and degradation. Overall, at 1 week after balloon angioplasty, GM6001 resulted in a 33% reduction in collagen content in balloon-injured arteries compared with placebo (750 +/- 143 to 500 +/- 78 micrograms hydroxyproline per segment, P < .004), which was associated with a nonsignificant 25% reduction in intimal area. Our data suggest that degradation of newly synthesized collagen is an important mechanism regulating collagen accumulation and that MMPs have an integral role in collagen turnover after balloon angioplasty.

Increased Expression of Elastolytic Cysteine Proteases, Cathepsins S and K, in the Neointima of Balloon-Injured Rat Carotid Arteries

“…[12][13][14][15] We believe that our experiments represent the first characterization of the expression of elastolytic cathepsins and their inhibitor in the rat carotid artery balloon-injury model.…”

“…7,8,11 However, previous observations have suggested that the even effective inhibition of MMPs and serine proteases might not sufficiently arrest neointima formation. [12][13][14][15] Cathepsins, lysosomal proteases within the papain superfamily, are thought to generally reside in and function optimally within acidic lysosomes. 16 Despite their lysosomal origin and optimal acidic pH, some of cathepsins including cathespin S and K can be secreted and retain a large portion of their proteolytic activity at neutral pH.…”

Type IV collagenase (matrix metalloproteinase-2 and -9) in prostate cancer

“…Zymographic techniques are used for the detection of enzymatic activities. 11 We found that MMP-9 was associated with prostate cancer in tissue and serum specimens. We also detected a change in the ratio of the active form and proform of MMP-2 in prostate cancer.…”

“…The zymography was conducted according to established reports 11,13 with minor modifications. Briefly, fresh prostatic issues were cut into small pieces and mixed with ice-cold extraction buffer (50 mM Tris-HCl pH7.4, 1% NP-40, 150 mM NaCl, 1 mM EDTA).…”

Inhibition of Matrix Metalloproteinase Activity Attenuates Tenascin-C Production and Calcification of Implanted Purified Elastin in Rats

“…18,19 For example, after arterial injury, TN-C and MMPs 20 are up-regulated during the development of occlusive neointimal lesions, whereas inhibition of MMP activity attenuates this process. 21 In addition, both MMP-2 22 and TN-C 23,24 are able to bind the same cell surface receptor, the ␣v␤3 integrin, further indicating that their regulation and functions may be interdependent. In fact, we have recently shown that extracellular matrix protein proteolysis by MMPs activates TN-C transcription via an ERK1/2 MAPK-dependent signaling pathway.…”