Plasma MMP-9 - a marker of carotid plaque instability

Antidiabetic PPAR gamma-activator rosiglitazone reduces MMP-9 serum levels in type 2 diabetic patients with coronary artery disease

BACKGROUND

Matrix metalloproteinases (MMPs) are critically involved in the development of unstable plaques. Although arteriosclerotic lesions in patients with diabetes mellitus are more unstable than those of nondiabetic subjects, nothing is known about serum levels of MMPs in these patients or about mechanisms to modulate MMP levels. We investigated MMP levels in diabetic and nondiabetic coronary artery disease (CAD) patients and performed a clinical trial to assess the effect of the PPARgamma-activating, antidiabetic thiazolidinedione rosiglitazone on MMP levels in diabetic CAD patients.

METHODS AND RESULTS

In CAD patients, MMP-2, -8, and -9 serum levels were significantly higher in type 2 diabetic subjects compared with age-, sex-, and body mass index-matched nondiabetics. Thirty-nine diabetic patients with CAD were randomized to receive rosiglitazone 4 mg (twice daily) or placebo for 12 weeks. Rosiglitazone treatment, but not placebo, significantly reduced MMP-9 levels already after 2 weeks by -19.6% (-38.3% to 8.6%, P<0.05), and levels remained suppressed until the end of the study. In addition, rosiglitazone significantly decreased serum amyloid A (SAA) and tumor necrosis factor-alpha levels.

CONCLUSION

MMP-9 levels are increased in type 2 diabetic patients with CAD, and treatment of these patients with the antidiabetic PPARgamma-activator rosiglitazone significantly reduces MMP-9, tumor necrosis factor-alpha, and SAA serum levels. These data support anti-inflammatory and potential antiatherogenic effects of thiazolidinediones.

Prospective, randomized, double-blind trial investigating the effect of doxycycline on matrix metalloproteinase expression within atherosclerotic carotid plaques

BACKGROUND AND PURPOSE

Elevated levels of matrix metalloproteinases (MMPs), particularly MMP-1 and MMP-9, have been implicated in plaque rupture. It has been suggested that inhibition of MMPs may stabilize vulnerable atherosclerotic plaques and improve clinical outcome. The aim of the study was to investigate the ability of doxycycline, a nonspecific MMP inhibitor, to reduce MMP concentration in carotid atheroma.

METHODS

The study design was a prospective, double-blind randomized trial. One hundred patients requiring carotid endarterectomy were randomized to receive 200 mg/d doxycycline or placebo for 2 to 8 weeks before surgery. During endarterectomy, carotid plaques were retrieved. The concentrations of MMPs and doxycycline were determined in the atherosclerotic tissue by enzyme-linked immunosorbent assay and high-performance liquid chromatography, respectively. Clinical events were recorded, as was the rate of preoperative embolization (transcranial Doppler).

RESULTS

Analysis of endarterectomized specimens demonstrated a mean doxycycline concentration of 6.0 micro g/g wet weight in treated patients. Administration of doxycycline significantly reduced the concentration of MMP-1 in carotid plaques from a mean of 14.8 to 10.3 ng/100g wet weight (P=0.038). This difference was due to decreased MMP-1 transcript (P<0.001). There was no difference in any other MMP (MMP-2, -3, or -9) or tissue inhibitor of matrix metalloproteinases-1 or -2.

CONCLUSIONS

Doxycycline penetrated atherosclerotic plaques with acceptable tissue levels. This resulted in a reduction in MMP-1 concentration because of decreased expression.

Effect of rosiglitazone treatment on nontraditional markers of cardiovascular disease in patients with type 2 diabetes mellitus

BACKGROUND

Markers of systemic inflammation (eg, C-reactive protein [CRP] and interleukin-6 [IL-6]) have been proposed to be "nontraditional" risk factors for cardiovascular disease in patients with type 2 diabetes mellitus. Matrix metalloproteinase-9 (MMP-9) has been implicated in the pathogenesis of atherosclerotic plaque rupture, which raises the possibility of the use of MMP-9 levels as a marker for future myocardial infarction or unstable angina. In vitro and animal studies suggest that thiazolidinediones can reduce the expression of these markers. The purpose of this analysis was to determine whether rosiglitazone alters serum concentrations of CRP, IL-6, MMP-9, and white blood cell count (WBC) and to examine the relationship of these effects with demographic and disease variables.

METHODS AND RESULTS

CRP, IL-6, MMP-9, and WBC were analyzed from stored frozen serum samples obtained from patients with type 2 diabetes who completed a 26-week randomized, double-blind, placebo-controlled study. After 26 weeks of rosiglitazone treatment, the percentage reductions in mean CRP, MMP-9, and WBC levels were statistically significant compared with baseline and placebo (P<0.01). The percentage reduction in mean IL-6 was small and similar in the rosiglitazone and placebo groups. The change in each inflammatory marker from baseline to week 26 was significantly correlated (P<0.05) with each of the other markers, as well as with the homeostasis model assessment estimate of insulin resistance.

CONCLUSIONS

Rosiglitazone reduces serum levels of MMP-9 and the proinflammatory marker CRP in patients with type 2 diabetes, which indicates potentially beneficial effects on overall cardiovascular risk.

Matrix metalloproteinases and atherosclerotic plaque instability

BACKGROUND

There is growing interest in the role of matrix metalloproteinases in atherosclerosis. Excessive tissue remodelling and increased matrix metalloproteinase activity have been demonstrated during atherosclerotic plaque disruption, a frequent predeterminant of ischaemic cardiac events and stroke. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology.

METHODS

The core of this review is derived from a Medline database literature search.

RESULTS

There is convincing evidence of increased matrix metalloproteinase activity during acute plaque disruption. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in models of vascular disease suggest a potential therapeutic benefit.

CONCLUSION

In vivo studies of matrix metalloproteinase inhibition are required to study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies acute plaque disruption.

The role of matrix metalloproteinases in vascular disease

There is growing interest in the role of matrix metalloproteinases in vascular diseases. These conditions are often characterized by excessive tissue remodelling, and increased matrix metalloproteinase activity has been demonstrated in aneurysms, intimal hyperplasia and atherosclerotic plaque disruption. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology. The core of this review is derived from a MEDLINE database literature search. The review found that there is convincing evidence of increased matrix metalloproteinase activity in a spectrum of vascular disease. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in vascular disease models suggest potential therapeutic benefit. In conclusion, in vivo studies of matrix metalloproteinase inhibition are required to further study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies vascular disorders.