Plasma MMP-9 - a marker of carotid plaque instability

Matrix Metalloproteinase-9 and Postoperative Outcomes in Carotid Endarterectomy: A Systematic Review

Background/Objectives: Carotid endarterectomy (CEA) is the treatment of choice for severe symptomatic and asymptomatic carotid artery stenosis. Nonetheless, it carries risks and several complications, including stroke and death. Previous studies have indicated that elevated matrix metalloproteinase-9 (MMP-9) levels may serve as biomarkers for adverse outcomes after CEA. This systematic review investigates the association between plasma MMP-9 levels and adverse cardiovascular outcomes following CEA. Methods: PubMed/MedLine, Scopus and Web of Science were searched for studies assessing the relationship between plasma MMP-9 levels and postoperative outcomes after CEA. Assessment of studies' quality was performed using the National Heart, Lung, and Blood Institute (NHLBI) Study Quality Assessment Tool for observational cohorts and cross-sectional studies. Results: Five studies were included (n = 891 participants). All five were retrospective cohort studies. MMP-9 was significantly higher in patients who presented with a combination of amaurosis fugax, central retinal artery occlusion, TIA and minor/major stroke at follow-up. However, individual outcomes like TIA or stroke did not consistently correlate with MMP-9 levels. Additionally, increased MMP-9 levels were also associated with cognitive dysfunction post CEA. Conclusions: Despite the potential of MMP-9 levels to serve as a biomarker for predicting postoperative cerebrovascular complications, this review presents limitations, including a high risk of bias in included studies and variability in methodologies. There is a need for further research with larger cohorts to validate these findings and improve risk stratification and management strategies for patients undergoing CEA.

Short-Term Atorvastatin Therapy in Healthy Individuals Results in Unaltered Plasma MMP Levels and Disrupted MMP-7 Correlation with Blood Lipids and Blood Count-Derived Inflammatory Markers

Background: Matrix metalloproteinases (MMPs) play an important role in the pathophysiology of atherosclerosis. Reportedly, statins can decrease MMP activity in patients with atherosclerotic cardiovascular disease, but this effect has not been studied in healthy individuals. Methods: MMPs 2, 7, and 9 and several other parameters were measured before and after a four-week course of moderate-dose atorvastatin (20 mg/day) in 21 healthy individuals. Results: Atorvastatin treatment resulted in lower total cholesterol, LDL-cholesterol, non-HDL-cholesterol, and triglycerides (p < 0.001 for all), but higher levels of plasma enzymes AST, ALT, CK, and LDH (p < 0.05 for all). No effect of atorvastatin on plasma MMP median concentrations was recorded. Before treatment, moderate positive significant correlations were found between MMP-7 and age, blood lipids, and blood count-derived inflammatory markers. Pre-treatment MMP-7 was best predicted by the total cholesterol-to-HDL cholesterol ratio in a remnant cholesterol-weighted least squares regression model. After atorvastatin treatment, MMP-7 no longer correlated with these markers. Conclusions: While the effect of statins on plasma MMPs in atherosclerosis is controversial, short-term moderate-dose atorvastatin treatment does not seem to affect levels of MMPs 2, 7, and 9 in healthy individuals. However, an intriguing correlation between MMP-7 and atherosclerosis-related blood lipids and neutrophil-associated inflammatory biomarkers seems to be disrupted by atorvastatin independently of hsCRP, possibly via pleiotropic effects.

Matrix metallopeptidase 9 contributes to the beginning of plaque and is a potential biomarker for the early identification of atherosclerosis in asymptomatic patients with diabetes

AIMS

To determine the roles of matrix metallopeptidase-9 (MMP9) on human coronary artery smooth muscle cells (HCASMCs) in vitro, early beginning of atherosclerosis in vivo in diabetic mice, and drug naïve patients with diabetes.

METHODS

Active human MMP9 (act-hMMP9) was added to HCASMCs and the expressions of MCP-1, ICAM-1, and VCAM-1 were measured. Act-hMMP9 (n=16) or placebo (n=15) was administered to diabetic KK.Cg-Ay/J (KK) mice. Carotid artery inflammation and atherosclerosis measurements were made at 2 and 10 weeks after treatment. An observational study of newly diagnosed drug naïve patients with type 2 diabetes mellitus (T2DM n=234) and healthy matched controls (n=41) was performed and patients had ultrasound of carotid arteries and some had coronary computed tomography angiogram for the assessment of atherosclerosis. Serum MMP9 was measured and its correlation with carotid artery or coronary artery plaques was determined.

RESULTS

In vitro, act-hMMP9 increased gene and protein expressions of MCP-1, ICAM-1, VCAM-1, and enhanced macrophage adhesion. Exogenous act-hMMP9 increased inflammation and initiated atherosclerosis in KK mice at 2 and 10 weeks: increased vessel wall thickness, lipid accumulation, and Galectin-3+ macrophage infiltration into the carotid arteries. In newly diagnosed T2DM patients, serum MMP9 correlated with carotid artery plaque size with a possible threshold cutoff point. In addition, serum MMP9 correlated with number of mixed plaques and grade of lumen stenosis in coronary arteries of patients with drug naïve T2DM.

CONCLUSION

MMP9 may contribute to the initiation of atherosclerosis and may be a potential biomarker for the early identification of atherosclerosis in patients with diabetes.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov, identifier NCT04424706.

FURIN suppresses the progression of atherosclerosis by promoting macrophage autophagy

FURIN, a member of the mammalian proprotein convertases (PCs) family, can promote the proteolytic maturation of proproteins. It has been shown that FURIN plays an important role in the progression of atherosclerosis (AS). Current evidence indicates that autophagy widely participates in atherogenesis. This study aimed to explore whether FURIN could affect atherogenesis via autophagy. The effect of FURIN on autophagy was studied using aortic tissues from aortic dissection patients who had BENTALL surgery, as well as macrophages and ApoE-/- mice. In atherosclerotic plaques of aortic tissues from patients, FURIN expression and autophagy were elevated. In macrophages, FURIN-shRNA and FURIN-overexpression lentivirus were used to intervene in FURIN expression. The results showed that FURIN overexpression accelerated LC3 formation in macrophages during the autophagosome formation phase. Furthermore, FURIN-induced autophagy resulted in lower lipid droplet concentrations in macrophages. The western blot revealed that FURIN regulated autophagy via the AMPK/mTOR/ULK1/PI3KIII signaling pathway. In vivo, FURIN overexpression resulted in increased macrophage LC3 formation in ApoE-/- mice atherosclerotic plaques, confirming that FURIN could inhibit the progression of AS by promoting macrophage autophagy. The present study demonstrated that FURIN suppressed the progression of AS by promoting macrophage autophagy via the AMPK/mTOR/ULK1/PI3KIII signaling pathway, which attenuated atherosclerotic lesion formation. Based on this data, current findings add to our understanding of the complexity of AS.

The role of magnetic resonance imaging and the expression of MMP-9 protein in the analysis of carotid atherosclerotic plaques in patients undergoing carotid endarterectomy: a prospective pilot study

Components of carotid atherosclerotic plaque can be analysed preoperatively by non-invasive advanced imaging modalities such as magnetic resonance imaging (MRI). The expression of matrix metalloproteinase-9 protein (MMP-9), which has a potential role in remodelling of atherosclerotic plaques, can be analysed immunohistochemically. The aim of the present prospective pilot study is to analyse histological characteristics and expression of MMP-9 in carotid plaques of patients undergoing carotid endarterectomy (CEA) and to investigate the correlation with preoperative clinical symptoms and MRI features. Preoperative clinical assessment, MRI imaging, postoperative histological and immunohistochemical analyses were performed. Fifteen patients with symptomatic (7/15; 47%) and asymptomatic carotid artery stenosis undergoing CEA were included. Among symptomatic patients, 5 (71%) had recent stroke and 2 (29%) had recent transient ischaemic attack with a median timing of 6 weeks (IQR: 1, 18) before the surgery. Both groups did not significantly differ in respect to preoperative characteristics. Prevalence of unstable plaque was higher in symptomatic than asymptomatic patients, although it was not significant (63% vs. 37%, p = 0.077). The expression of MMP-9 in CD68 cells within the plaque by semiquantitative analysis was found to be significantly higher in symptomatic as compared to asymptomatic patients (86% vs. 25% with the highest expression, p = 0.014). The average microvascular density was found to be higher and lipid core area larger among both symptomatic patients and unstable carotid plaque specimens, although this did not reach statistical significance (p = 0.064 and p = 0.132, p = 0.360 and p = 0.569, respectively). Our results demonstrate that MRI is reliable in classifying carotid lesions and differentiating unstable from stable plaques. We have also shown that the expression of MMP-9 is significantly higher among symptomatic patients undergoing CEA.

Increased serum level of high sensitivity troponin T even prior to surgery can predict adverse events during carotid endarterectomy

OBJECTIVES

Perioperative stress affects the outcome of carotid endarterectomy performed under regional anesthesia. Here we aimed to explore the temporal profile of the stress marker cortisol and its relationship to high-sensitivity troponin-T, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and S100B as an indicator of blood-brain barrier alteration in the systemic circulation.

METHODS

Prospective part of the study: a total of 31 patients with significant carotid stenosis scheduled for carotid endarterectomy in regional anesthesia were enrolled. Follow-up part of the study and retrospective analysis of the outcome: each patient was followed up to five years and morbidity as well as mortality data were collected from an electronic database. Blood samples from each patient were serially taken; prior to surgery (T1), at the time of reperfusion (T2), 24 h (T3) and 72 h later postoperatively (T4), then the plasma concentration of each biomarker was measured. Besides, the clinical and surgical factors and perioperative adverse events were recorded.

RESULTS

More positive correlations were found between: the early change of S100B (T2-T1) and late change in plasma cortisol level (T4-T3) (r = 0.403; p < 0.05); the early change of cortisol (T2-T1) and the early postoperative change of plasma matrix metalloproteinase-9 level (T3-T2) (r = 0.432; p = 0.01); the plasma concentration of tissue inhibitor of metalloproteinase-1 at 24 postoperative hours and the late change in plasma high-sensitivity troponin-T level (T4-T3) (r = 0.705; p < 0.001). Five patients needed an intraoperative shunt in whom the high-sensitivity troponin-T was elevated even prior to surgery, but definitive stroke never occurred. Plasma matrix metalloproteinase-9 concentration at reperfusion independently predicted the five-year mortality with a cut-off value of 456 ng/ml (sensitivity: 86%, specificity: 84%, area 0.887, p = 0.002).

CONCLUSIONS

A higher intraoperative change in S100B level reflecting carotid endarterectomy induced acute silent brain ischemia was associated with more pronounced post-operative change of cortisol. An early elevation of cortisol was found to be associated with a delayed increase of matrix metalloproteinase-9. Importantly, an increased high-sensitivity troponin-T even prior to carotid endarterectomy may predict clamp intolerance, and elevated matrix metalloproteinase-9 at reperfusion suggests a poor outcome.

Using Serum Biomarkers for Identifying Unstable Carotid Plaque: Update of Current Evidence

Carotid atherosclerosis is responsible for a great proportion of ischemic strokes. Early identification of unstable or vulnerable carotid plaques, and therefore, of patients at high risk for stroke, is of significant medical and socioeconomical value. We reviewed the current literature and discussed the potential role of the most important serum biomarkers in identifying patients with carotid atherosclerosis who are at high risk for atheroembolic stroke.

Contrast imaging ultrasound for the detection and characterization of carotid vulnerable plaque

Not only the degree of luminal narrowing but also the plaque morphology and composition play an important role in risk stratification of carotid atherosclerotic lesions. During the last few years, carotid contrast-enhanced ultrasound (CEUS) has emerged as a valuable imaging tool to assess such vulnerable carotid plaques. This review article discussed the use of CEUS for the detection of carotid plaque irregularities and ulcerations as well as the quantification of intraplaque neovascularization and its correlation with histology and inflammatory biomarkers. Apart from evaluating for markers of vulnerable carotid plaques, CEUS enhancement is directly associated with past cerebrovascular events. More importantly, preliminary evidence has shown that CEUS could be used to predict future cerebrovascular and cardiovascular events. Despite the progress in CEUS imaging for carotid atherosclerotic disease, past studies still suffer from the retrospective nature, small sample size, and a lack of matched, well controlled prospective studies. In the future, large multi-center prospective studies addressing the relationship between CEUS findings and patient clinical outcomes in carotid atherosclerotic disease are warranted.

Matrix Metalloproteinases as Biomarkers of Atherosclerotic Plaque Instability

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases responsible for tissue remodeling and degradation of extracellular matrix (ECM) proteins. MMPs may modulate various cellular and signaling pathways in atherosclerosis responsible for progression and rupture of atherosclerotic plaques. The effect of MMPs polymorphisms and the expression of MMPs in both the atherosclerotic plaque and plasma was shown. They are independent predictors of atherosclerotic plaque instability in stable coronary heart disease (CHD) patients. Increased levels of MMPs in patients with advanced cardiovascular disease (CAD) and acute coronary syndrome (ACS) was associated with future risk of cardiovascular events. These data confirm that MMPs may be biomarkers in plaque instability as they target in potential drug therapies for atherosclerosis. They provide important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification.

Plasma levels of matrix metalloproteinase-9: A possible marker for cold-induced stroke risk in hypertensive rats

The cold weather is associated with an increased occurrence of acute stroke events. However, the underlying mechanisms have not yet been fully elucidated. In the present study, we investigated whether plasma matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels as well as the MMP-9/TIMP-1 ratio could be used as predictor for cold-induced stroke risk in hypertensive rats. A total of 50 male rats were subjected to either control group or 2-kidney, 2-clip (2K - 2C) group (N = 25, each), After blood pressure was stabilized, rats were placed in an intelligent artificial climate chamber and maintained on a 12-h light (22 °C)/dark (4 °C) cycle for 3 days. Plasma levels of MMP-9 and TIMP-1 were measured before and after cold exposure from 50 rats by ELISA. Pretreatment plasma MMP-9 levels were significantly higher in 2K-2C rats than in the controls (P <  0.05), TIMP-1 levels were significantly lower in 2K-2C rats than in the controls (P <  0.05), pretreatment plasma MMP-9 levels were significantly higher in those with cold-induced stroke compared to those without (P <  0.05). Logistic regression analysis showed that only plasma MMP-9 levels remained independently associated with cold-induced stroke after adjusting for potential confounders (OR, 1.17; 95% CI, 1.08 to 1.32; P < 0.007). In contrast, no correlation was observed between systolic blood pressure (SBP), TIMP-1 or MMP-9/TIMP-1 ratio and the cold-induced stroke. Higher plasma MMP-9 levels are significantly correlated with cold-induced stroke in hypertensive rats treated with intermittent cold stress. Plasma MMP-9 may be as a promising biomarker to predict the risk of cold-induced stroke events in hypertensive rats.

Interleukin-18, matrix metalloproteinase-22 and -29 are independent risk factors of human coronary heart disease

BACKGROUND

Coronary heart disease (CHD) is characterized by arterial wall inflammation and matrix degradation. Matrix metalloproteinase (MMP)-22 and -29 and pro-inflammatory cytokine interleukin-18 (IL18) are present in human hearts. IL18 may regulate MMP-22 and -29 expression, which may correlate with CHD progression.

METHODS AND RESULTS

Immunoblot analysis showed that IL18 induced MMP-22 expression in human aortic smooth muscle cells. The Mann Whitney test from a prospective study of 194 CHD patients and 68 non-CHD controls demonstrated higher plasma levels of IL18, MMP-22 and -29 in CHD patients than in the controls. A logistic regression test suggested that plasma IL18 (odds ratio (OR)=1.131, P=0.007), MMP-22 (OR=1.213, P=0.040), and MMP-29 (OR=1.198, P=0.033) were independent risk factors of CHD. Pearson's correlation test showed that IL18 (coefficient (r)=0.214, P=0.045; r=0.246, P=0.031) and MMP-22 (r=0.273, P=0.006; r=0.286, P=0.012) were associated with the Gensini score before and after adjusting for potential confounding factors. The multivariate Pearson's correlation test showed that plasma MMP-22 levels correlated positively with high-sensitive-C-reactive protein (hs-CRP) (r=0.167, P=0.023), and MMP-29 levels correlated negatively with triglyceride (r=-0.169, P=0.018). Spearman's correlation test indicated that plasma IL18 levels associated positively with plasma MMP-22 (r=0.845, P<0.001) and MMP-29 (r=0.548, P<0.001).

CONCLUSIONS

Our observations suggest that IL18, MMP-22 and -29 serve as biomarkers and independent risk factors of CHD. Increased systemic IL18 in CHD patients may contribute to elevated plasma MMP-22 and -29 levels in these patients.

Late mitral restenosis after percutaneous commissurotomy: Predictive value of inflammation and extracellular matrix remodeling biomarkers

BACKGROUND

The role of chronic inflammation in mitral restenosis after percutaneous mitral commissurotomy (PMC) is still controversial.

AIMS

We sought to assess the predictive value of inflammation and extracellular matrix (ECM) remodeling biomarkers in late mitral restenosis after PMC.

METHODS

We prospectively enrolled 155 patients (mean age 46.2±11 years) with at least 5 year follow up after primary PMC. Serum levels of high sensitive C-Reactive Protein (hs-CRP), matrix metalloproteinases MMPs, tissue-specific inhibitors of matrix metalloproteinases TIMPs, and tumor necrosis factor α (TNFα)] were measured.

RESULTS

Late mitral restenosis occurred in 55 patients (35.5%). The independent predictors of late mitral stenosis were: age> 55 years [HR10.51 (95%CI 1.12-95.9); p=0.037]; no long acting penicillin therapy [HR 18.1 (95% CI 2.6-122.9); p=0.003]; TNFα > 80 ng/ml [HR 5.85 (95% CI 1.1-31.42); p=0.039]; and TIMP-2 > 289 ng/ml [HR 0.52 (95% CI 0.22-0.95); p=0.045].

CONCLUSION

Chronic inflammation and ECM remodeling are involved in late mitral restenosis after PMC.

Overexpression of CCN3 inhibits inflammation and progression of atherosclerosis in apolipoprotein E-deficient mice

Background

Cysteine-rich 61/connective tissue growth factor/nephroblastoma overexpressed (CCN) 3 has been recently reported to play a role in regulating inflammation of vascular endothelial cells. However, the role of CCN3 in atherosclerosis, which is characterized by vascular inflammation, remains unclear.

Hypothesis and Objectives

Overexpression of CCN3 may relieve the inflammation response in and inhibit the progress of atherosclerosis. We aimed to explore the potential roles of CCN3 in inflammation in atherosclerosis.

Strategy and Main Results

In in vitro studies using cultured human aortic endothelial cells and human umbilical vein endothelial cells, CCN3 mRNA and protein expression significantly decreased in response to tumor necrosis factor-α and interleukin-1β treatments (p<0.05), when analyzed by quantitative real-time polymerase chain reaction and Western blot. Using a mouse model of atherosclerosis, the mRNA and protein levels of CCN3 decreased by 72.2% (p = 0.041) and 86.4% (p = 0.036), respectively, compared with levels in wild-type control mice, respectively. Overexpression of CCN3 by adenovirus-mediated gene overexpression decreased low-density lipoprotein cholesterol by 48.9% (p = 0.017), total cholesterol by 58.9% (p = 0.031), and triglycerides by 56.8% (p = 0.022), and it increased high-density lipoprotein cholesterol level by 2.16-fold (p = 0.039), compared with control groups. Additionally, a reduced plaque area and increased fibrous cap were observed (p<0.05). Furthermore, CCN3 overexpression decreased cell adhesion molecule-1 mRNA expression by 84.7% (p = 0.007) and intercellular adhesion molecule-1 mRNA expression by 61.2% (p = 0.044). Inflammatory factors, including matrix metalloproteinases, cyclooxygenase 2, and tissue factor also significantly (p<0.05) decreased with CCN3 overexpression in the atherosclerotic mouse model. Additionally, CCN1 and CCN2, which have been reported to be highly expressed in aortic atherosclerotic plaques, were significantly downregulated (p<0.05) by CCN3 overexpression.

Conclusion

CCN3 overexpression is associated with control of inflammatory processes and reversion of dyslipidemia in the process of atherosclerosis, which implies that CCN3 may be a promising target in the treatment of atherosclerosis.

The Pathogenic Role of the Adaptive Immune Response to Modified LDL in Diabetes

The main causes of morbidity and mortality in diabetes are macro and microvascular complications, including atherosclerosis, nephropathy, and retinopathy. As the definition of atherosclerosis as a chronic inflammatory disease became widely accepted, it became important to define the triggers of vascular inflammation. Oxidative and other modifications of lipids and lipoproteins emerged as major pathogenic factors in atherosclerosis. Modified forms of LDL (mLDL) are pro-inflammatory by themselves, but, in addition, mLDLs including oxidized, malondialdehyde (MDA)-modified, and advanced glycation end (AGE)-product-modified LDL induce autoimmune responses in humans. The autoimmune response involves T cells in the arterial wall and synthesis of IgG antibodies. The IgG auto-antibodies that react with mLDLs generate immune complexes (IC) both intra and extravascularly, and those IC activate the complement system as well as phagocytic cells via the ligation of Fcγ receptors. In vitro studies proved that the pro-inflammatory activity of IC containing mLDL (mLDL-IC) is several-fold higher than that of the modified LDL molecules. Clinical studies support the pathogenic role of mLDL-IC in the development of macrovascular disease patients with diabetes. In type 1 diabetes, high levels of oxidized and AGE-LDL in IC were associated with internal carotid intima-media thickening and coronary calcification. In type 2 diabetes, high levels of MDA-LDL in IC predicted the occurrence of myocardial infarction. There is also evidence that mLDL-IC are involved in the pathogenesis of diabetic nephropathy and retinopathy. The pathogenic role of mLDL-IC is not unique to diabetic patients, because those IC are also detected in non-diabetic individuals. But mLDL-IC are likely to reach higher concentrations and have a more prominent pathogenic role in diabetes due to increased antigenic load secondary to high oxidative stress and to enhanced autoimmune responses in type 1 diabetes.

Limited value of novel pulmonary embolism biomarkers in patients with coronary atherosclerosis

BACKGROUND

Recent research supports the efficacy of various plasma biomarkers in diagnosing pulmonary embolism (PE) including E-selectin, MMP-9, MPO, sVCAM-1, sICAM-1, adiponectin, hs-CRP and tPAI-1.

OBJECTIVE

We hypothesized that these biomarkers, which are affected in both venous and arterial thromboembolic diseases, have a limited potential of diagnosing PE in patients with concomitant coronary atherosclerosis, as assessed from a low-dose CT scan of the thorax, compared to patients without atherosclerosis.

METHODS

Consecutive patients suspected of PE were referred. All patients had a ventilation/perfusion single photon emission tomography (V/Q-SPECT), low-dose pulmonary CT, pulmonary multidetector computer tomography angiography, blood samples and ECG-gated cardiac CT performed the same day.

RESULTS

A total of 69 patients were included, of which 28 (41%) had PE. In patients without coronary calcium, MMP-9 and tPAI-1 were significantly elevated (P<0·042 and P<0·049) in patients diagnosed with PE. From the receiver operating curves, we chose a cut-off value for MMP-9 at 164·4 ng l(-1) , which yielded sensitivity, specificity, positive and negative predictive values of 63%, 78%, 71% and 70%, respectively. With a chosen cut-off value for tPAI-1 at 56·3 ng l(-1) , the sensitivity, specificity, positive and negative predictive values were 88%, 89%, 88% and 89%, respectively. In patients with coronary calcium, none of the biomarkers could discriminate between PE and no PE.

CONCLUSION

Plasma levels of tPAI-1 and MMP-9 are potentially useful in patients suspected of PE, however, not in the presence of the coronary atherosclerosis.

Circulating matrix metalloproteinases in infective endocarditis: a possible marker of the embolic risk

Background

Embolic events (EE) in infective endocarditis (IE) are caused by fragmentation of vegetations or valvular tissue. Vegetation length is considered to be the most potent predictor of EE, but does not take into account the degree of friability of the vegetation and of the surrounded infected tissue. Matrix metalloproteinases (MMPs) are enzymes involved in degradation of matrix extracellular components and play a role in the pathophysiology of IE. We aimed to determine whether, in addition to the vegetation size, circulating MMPs could provide accurate predictive value of embolism in IE.

Methods

Among 145 patients referred for a native valve IE, we prospectively included 16 patients who experienced EE during antibiotic therapy (new-EE) and 30 patients without new-EE and treated without valvular surgery. A control group of 38 patients with a degenerative valvular heart disease was also included. In addition to clinical, microbiological and echocardiographic assessment, blood MMPs and their inhibitors were assayed in all patients at admission.

Results

MMP-9 serum level was significantly higher in patients with new-EE compared to controls (median [interquartile range]; 250 ng/mL [175–455] vs. 111 ng/mL [70–144], respectively; p<0.0001) and patients with no new-EE (250 ng/mL [175–455] vs. 138 ng/mL [95–232]; p<0.01). A higher MMP-9 activity in patients who experienced new-EE was further confirmed by gelatin zymography analysis. Circulating MMP-9 remains a predictor of new-EE after adjustment for vegetation length and other potential confounders. This parameter provided incremental predictive value over vegetation measurements.

Conclusions

MMP-9 serum level is associated with the risk of embolism during IE. This marker might help physicians in the management of the disease, but further propspective studies are need to confirm these preliminary results.

Evaluation of serum matrix metalloproteinases as biomarkers for detection of neurological symptoms in carotid artery disease

OBJECTIVE

Relevant soluble matrix metalloproteinases (MMPs), their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), and serological factors were analyzed as possible biomarkers for neurological symptoms in patients with carotid artery stenosis.

METHODS AND RESULTS

Asymptomatic (n = 76) and symptomatic (n = 69) patients were evaluated. Serum levels of collagenases (MMP-1, -8), gelatinases (MMP-2, -9), stromelysin (MMP-3), matrilysin (MMP-7), and TIMP-1, -2 were determined by enzyme-linked immunosorbant assay (ELISA). Furthermore, fibrinogen, C-reactive protein (CRP), leukocytes, and further serological parameters were measured. Circulating MMP-7, -8, -9, and TIMP-1 were significantly enhanced in symptomatic individuals with P < .001 for MMP-7 and P < .05 for MMP-8, -9, and TIMP-1. Significant correlations were found between various MMPs with highest correlation coefficient of r = .749 between MMP-8 and -9. In addition, MMP-1, -3, -7, -9 correlated significantly with leukocytes, MMP-1, and TIMP-1 with thrombocytes, MMP-8 with fibrinogen, and MMP-7 with creatinine. Combination of more than one biomarker led to significantly enhanced positive predictive value (PPV) for neurological symptom compared to single MMP (MMP-7 + MMP-9: PPV = 73.1%, MMP-7 + MMP-8 + MMP-9: PPV = 73.8% vs. PPV = 62.5%; P < .001).

CONCLUSIONS

Thus, using appropriate analytical approaches, we showed for the first time the possibility to use set of relevant biomarkers as predictors of neurological symptoms. Such biomarkers together with current diagnostic techniques may further contribute to recognize vulnerable lesions to define patients at risk.

The effect of metformin treatment on VEGF and PAI-1 levels in obese type 2 diabetic patients

The aim of the study was to evaluate the effect of metformin on markers of endothelial function, vascular inflammation and factors of thrombosis in obese type 2 diabetic patients. Twenty-four type 2 diabetic patients (15 female, 9 male) previously under medical nutrition treatment (MNT)+regular exercise programme (REP) without chronic micro or macrovascular complications with the mean age of 50.5+/-1.5 years, diabetes duration of 17.9+/-6.3 months and body mass index (BMI) of 31.7+/-0.8 kg/m(2) were enrolled in the study. In the first 4 weeks, all the patients continued MNT+REP. In the following 12 weeks, metformin (mean daily dosage of 1381+/-85 mg) was added. After the first period with MNT+REP, BMI, waist circumference, fat percentage, blood pressure and HDL cholesterol decreased significantly. After metformin addition, there was a significant decrement in BMI, waist circumference, fat percentage, fasting and postprandial plasma glucose, hemoglobin A1C, plasminogen activator inhibitor-1 (PAI-1), vascular endothelial growth factor (VEGF) and increment in beta cell reserve values of the patients. Our results indicated that, metformin addition had beneficial effect on VEGF and PAI-1 levels in obese type 2 diabetic patients under MNT+REP, independent from its' favourable effects on BMI and glycemic control.

MMP-9 haplotypes and carotid artery atherosclerosis: an association study introducing a novel multicolour multiplex RealTime PCR protocol

BACKGROUND

Among other matrix metalloproteinases (MMPs), gelatinase B (MMP-9) is discussed to be associated with the pathogenesis of vascular diseases. Two single nucleotide polymorphisms (SNPs) of the MMP-9 gene, C-1562T in the promoter region and a G/A transition in exon 6 (R + 279Q), have been addressed in previous association studies which, however, produced conflicting results.

MATERIAL AND METHODS

A novel multiplex RealTime PCR protocol for the fast and simultaneous detection of both polymorphisms is presented, which was used for genotyping 1737 participants of a prospective study investigating genetic factors influencing the progression of atherosclerosis.

RESULTS

Haplotype analysis revealed -1562C/+279Q as the major haplotype in this population. Allelic distribution of the C-1562T polymorphism was consistent with data published for similar cohorts; however, we found that R + 279Q allelic distribution appears to vary significantly among Caucasian populations. Considering clinical data available from 1487 participants, we found significant associations between the presence of atherosclerotic plaque and the CA-haplotype in men (P = 0.028, phi = 0.08), and between the AG variant of exon 6 and common carotid artery intima-media thickness (CIMT) in women (P = 0.004, Eta(2) = 0.019).

CONCLUSIONS

In summary, our results demonstrate associations of MMP-9 genotypes with different stages of carotid atherosclerosis.

Thiazolidinediones as anti-inflammatory and anti-atherogenic agents

In the last few years, there has been increasing focus on the impact of interventions on cardiovascular outcomes in patients with type 2 diabetes. Insulin resistance and hyperglycaemia often co-exist with a cluster of risk factors for coronary artery disease, but the underlying mechanisms leading to the development of such vascular complications are complex. The over-production of free radicals in patients suffering from diabetes results in a state of oxidative stress, which leads to endothelial dysfunction and a greater risk of atherosclerosis. Moreover, inflammatory factors which play a critical role in atherothrombosis and plaque rupture are often found to be at elevated levels in this patient population. Thiazolidinediones (TZDs) are now routinely used to manage glucose levels, and have been suggested to influence other cardiovascular risk factors and therefore the pathways leading to macrovascular events. Consequently, recent studies have investigated the anti-inflammatory and anti-atherogenic properties of TZDs. The data available up to the present time, in the context of the emerging cardiovascular outcome profiles of rosiglitazone and pioglitazone, will be discussed here.

Metalloproteinase Expression in Carotid Plaque and Its Correlation With Plasma Levels Before and After Carotid Endarterectomy

Purpose To assess baseline and follow-up plasma concentrations of metalloproteinase-9 (MMP-9), MMP-2, and tissue inhibitor of metalloproteinase-2 (TIMP-2) in patients undergoing carotid thromboendarterectomy (TEA) in relation to tissue expression and diagnostic features.

Basic Methods Using sandwich enzyme-linked immunosorbent assay, plasma levels of enzymes were determined in 15 patients undergoing carotid TEA. Tissue sections were incubated with specific antibodies and fluorescence intensity was analyzed.

Principal Findings MMP-9 levels were higher in patients with carotid stenosis versus controls, significantly in those with cerebral lesions at neuroimaging. MMP-9 levels decreased in 93.4% of the patients at 1 month. MMP-2 levels tended to increase 30 days after surgery. TIMP-2 showed no difference.

Conclusions High concentrations of MMP-9 found in patients with carotid stenosis and cerebral lesions suggest that MMP-9 assay could be useful in the evaluation of all carotid lesions to help identify those at highest risk of a neurologic event.

Elevated levels of anti-Chlamydia pneumoniae IgA and IgG antibodies in young adults with ischemic stroke

INTRODUCTION

Data on the role of Chlamydia pneumoniae in patients with ischemic stroke are inconsistent. We investigated the presence of anti-C. pneumoniae antibodies in young adults with ischemic stroke.

METHODS

94 patients (<55 years) with ischemic stroke and 103 controls were enrolled. Indices of anti-C. pneumoniae IgA and IgG were assessed with an ELISA. We determined OR and 95% CI for the IgA and IgG seropositivity in stroke cases.

RESULTS

Mean IgA and IgG indices were higher in stroke patients vs controls (IgA: 1.40 vs 0.56; P < 0.001; IgG: 0.85 vs. 0.78; P < 0.003). The IgA seropositivity was associated with stroke risk (11.92; 5.94-23.92; P < 0.001) as well as IgG seropositivity was (2.31; 1.15-4.61; P < 0.016). Seropositivity assessed with combined IgA and IgG indices was associated with increased stroke risk (OR 9.35; 95% CI 4.78-18.29; P < 0.0001). After controlling for age and sex, the IgA seropositivity yielded a significantly adjusted OR for stroke (8.95; 4.44-18.07; P < 0.002), while IgG seropositivity did not (0.85; 0.53-1.63).

CONCLUSIONS

We find an increased risk of stroke in young patients seropositive to C. pneumoniae in the IgA antibody class. Further studies to explore this finding are warranted.

Can We Talk about CD4+CD28– Lymphocytes as a Risk Factor for Ischemic Stroke?

BACKGROUND

CD4+CD28- lymphocytes are implicated in the destabilization of atheromatous plaque, leading to acute coronary episodes. One may ask whether these cells play a similar role in ischemic stroke pathogenesis with an atherosclerotic background.

METHODS

Flow cytometry was applied to determine the percentage of CD4+CD28- lymphocytes in the peripheral blood of patients during the acute phase of their first ischemic stroke (group I) and in patients without a history of stroke but with two of the most important risk factors (hypertension, diabetes) for atherosclerosis-related ischemic stroke (group II). The results were compared with healthy controls.

RESULTS

The median percentages of CD4+CD28- lymphocytes in groups I and II did not differ significantly, but for each of these groups the percentage was higher than in the control group. The time of blood sampling from onset of stroke, presence of the ischemic focus in the CT brain scan and severity of neurological deficits did not correlate with the percentage of CD4+CD28- lymphocytes.

CONCLUSIONS

We conclude that CD4+CD28- lymphocytes are implicated in mechanisms enhancing the risk of acute ischemic stroke and not a consequence of stroke.

Relationships between free radical levels during carotid endarterectomy and markers of arteriosclerotic disease

BACKGROUND

Free radical production is elevated in jugular venous blood emerging from the brain in conjunction with carotid endarterectomy. This study explores the relationships between markers for lesion progression in arteriosclerosis, production of radicals and clinical characteristics.

METHODS

The radical production during carotid endarterectomy was studied in 13 patients with an ex vivo spin trap method using OXANOH as a spin trap. MCP-1, ICAM-1, MMP-9 and oxLDL were determined in venous blood samples before, during and after clamping of the carotid artery. Principal component analysis (PCA) as well as partial least square regression analysis (PLS) was applied to interpret the data.

RESULTS

PCA and PLS analysis revealed that high values of MMP-9 and low values of ICAM-1 were associated with high radical production whereas MCP-1 and oxLDL were not correlated to radical production. MMP-9 was elevated at diabetes, high haemoglobin, high leucocyte counts and thrombocyte counts as well as at contralateral stenosis, whereas ICAM-1 showed reversed relationships to these clinical variables. MCP-1 increased during surgery.

CONCLUSIONS

The main finding in our study is that MMP-9 in plasma is asscociated with radical production during carotid endarterectomy, suggesting that this enzyme might be involved in the pathogenesis of brain damage in conjunction with ischaemia-reperfusion.

Phagocytic NADPH oxidase-dependent superoxide production stimulates matrix metalloproteinase-9: implications for human atherosclerosis

OBJECTIVE

Data suggest that matrix metalloproteinase-9 (MMP-9) has a role in atherosclerosis. The phagocytic NADPH oxidase has been also associated with atherosclerosis. This study aimed to investigate the association between phagocytic NADPH oxidase and MMP-9 in human atherosclerosis.

METHODS AND RESULTS

In vitro experiments performed in human monocytes showed that NADPH oxidase activation enhanced MMP-9 secretion and activity, determined by enzyme-linked immunosorbent assay and zymography, respectively. Immunohistochemical study showed that phagocytic NADPH oxidase localized with MMP-9 in endarterectomies from patients with carotid stenosis. In addition, a positive relationship (P<0.001) was found between phagocytic NADPH oxidase-dependent superoxide production determined with lucigenin and plasma MMP-9 levels in 188 asymptomatic subjects free of overt clinical atherosclerosis. In multivariate analysis, this association remained significant after adjustment for cardiovascular risk factors. Interestingly, subjects in the upper quartile of superoxide production exhibited the highest values of MMP-9, oxidized low-density lipoprotein, nitrotyrosine, carotid intima media thickness, and an increased presence of carotid plaques.

CONCLUSIONS

Enhanced NADPH oxidase-dependent *O2(-) production stimulates MMP-9 in monocytes and this relationship may be relevant in the atherosclerotic process. Moreover, MMP-9 emerges as an important mediator of the phagocytic NADPH oxidase-dependent oxidative stress in atherosclerosis.

High Risk Plaque, High Risk Patient or High Risk Procedure?

SAPPHIRE, a randomised trial of endarterectomy versus angioplasty in 'high-risk' patients, concluded that angioplasty was 'not inferior' to surgery. This has subsequently been translated to mean that angioplasty was 'preferable' or 'advisable' in patients considered high-risk for surgery, with no further discrimination between symptomatic and asymptomatic individuals. Moreover, there have been suggestions that the accepted procedural risks may have to be increased in these patients. In fact, 71% of patients in SAPPHIRE were asymptomatic in whom there was an average 6% 30-day death/stroke rate. At this level of risk, neither surgery nor angioplasty could ever prevent long-term stroke. The concept of identifying high-risk patients is laudable, but they should be high risk for stroke (i.e. symptomatic). There is currently little systematic evidence to include asymptomatic patients within this definition.

Role of platelet-derived growth factor and transforming growth factor beta1 the in the regulation of metalloproteinase expressions

BACKGROUND

We investigated the role and influence of platelet derived growth factor (PDGF) and transforming growth factor beta1 (TGF) in the pathologic mechanism at the basis of plaque instability regulating the expression of matrix metalloproteinases (MMPs).

METHODS

Plaques obtained from 70 patients who underwent carotid endarterectomy were classified histologically as stable or unstable. Serum levels of PDGF and TGF were measured pre- and postoperatively. The serum activities of MMP-2 and MMP-9 were also analyzed. Human umbilical artery smooth muscle cells (HUASMCs) were stimulated in vitro with PDGF at various concentrations (20 and 50 ng/mL) and TGF (2 and 5 ng/mL) in a serum-free medium. The release of MMPs in the conditioned medium was assessed by enzyme-linked immunosorbent assay. Release of the MMPs was confirmed by Western blot analysis; their activity and expression were determined by zymography and reverse transcription-polymerase chain reaction. Specific inhibition tests were performed on HUASMCs to evaluate the role of these growth factors.

RESULTS

Forty-two (60%) patients had an unstable carotid plaque and 28 (40%) a stable plaque. Preoperatively, patients affected with unstable carotid plaques had higher PDGF and lower TGF plasma levels than patients with stable carotid plaques (P < .001); the levels returned to normal at 1 and 30 days postoperatively, compared with 20 non-operated healthy volunteers. Release, activity, protein level, and expression of MMPs in PDGF-stimulated HUASMCs were greater than in the controls (P < .001), whereas these values in the TGF-stimulated HUASMCs were lower (P < .001). The addition of monoclonal anti-PDGF antibodies decreased the release, activity, protein level, and expression of MMPs, whereas the addition of monoclonal anti-TGF antibodies increased the release, activity, protein level and expression of MMPs (P < .001).

CONCLUSIONS

TGF seems to be an important stabilizing factor and prevents plaque rupture through the decrease of MMPs.

Effects of hormone replacement therapy type and route of administration on plasma matrix metalloproteinases and their tissue inhibitors in postmenopausal women

BACKGROUND

Matrix metalloproteinases (MMPs) are implicated in numerous disease states including cardiovascular disease and cancer. Because recent studies have shown a detrimental effect of hormone replacement therapy on cardiovascular disease and breast cancer, we investigated whether there are any differences in the concentrations of MMPs and their tissue inhibitors (TIMPs) in women receiving various forms of postmenopausal therapy.

MATERIAL AND METHODS

A total of 195 healthy postmenopausal women were assessed: 46 were taking tibolone, 47 were taking transdermal estradiol, 46 were taking conjugated equine estrogens (CEE), and 56 were not taking any menopausal therapy (CTR). Plasma levels of MMP-2 and -9 and TIMP-1 and TIMP-2 were measured by ELISA methods.

RESULTS

MMP-9 levels were significantly higher in the CEE group in comparison with healthy women not receiving menopausal therapy (P < 0.05). In contrast, MMP-9 levels in the tibolone group were significantly lower than in any other group (P < 0.01, compared with transdermal estradiol and CTR, and P < 0.001, compared with CEE). MMP-9 to TIMP-1 ratio was also significantly higher in the CEE, compared with CTR (P < 0.05), and lower in the tibolone group (P < 0.01, compared with all groups). MMP-2 levels were higher in the CEE group, compared with healthy women not receiving any menopausal therapy, and women taking tibolone (P < 0.05).

CONCLUSIONS

Our study demonstrates differential effects of various forms of postmenopausal therapy on serum levels of MMP-9 and MMP-2. It remains to be established whether these differences might be associated with differences in risks of cardiovascular disease and cancer in these women.

Heregulin, cysteine rich-61 and matrix metalloproteinase 9 expression in human carotid atherosclerotic plaques: relationship with clinical data

OBJECTIVES

Heregulins (HRGs) are known to induce expression of angiogenic factors such as cysteine rich-61 (CYR61) and collectively to promote neoangiogenesis. Along with extracellular matrix remodelling, mediated by matrix metalloproteinases (MMPs), these factors are important in atherogenesis. The aim of the present study was to investigate HRG, CYR61 and MMP-9 expression and their relationship with clinical and histopathological findings in carotid occlusive disease.

MATERIALS AND METHODS

Specimens of human carotid atherosclerotic plaque (n=90) were obtained by endarterectomy. Expression of HRG, CYR61 and MMP-9 was assessed by immunohistochemical and Western blot analysis. Associations between protein expression and degree of carotid stenosis, presence of symptoms, presence of an infarct in CT scan and carotid plaque histopathology were investigated.

RESULTS

An increase in HRG, CYR61 and MMP-9 expression was found, particularly in neovascularized regions of the plaques. High HRG expression was associated with the degree of carotid stenosis (p=0.028) and plaque histopathology (p=0.002). More than half of specimens from plaques with >90% stenosis had intense expression of CYR61 (p=0.047). Increased expression of MMP-9 was associated with degree of stenosis and presence of cerebral infarct on CT scan (p=0.05).

CONCLUSION

HRG, CYR61 and MMP-9 are highly expressed in human atherosclerotic carotid plaques. The association with the degree of stenosis and/or plaque histopathology implies an involvement in lesion progression.

Effect of Rosiglitazone Treatment on Plaque Inflammation and Collagen Content in Nondiabetic Patients

Background— Therapeutic strategies to stabilize advanced arteriosclerotic lesions may prevent plaque rupture and reduce the incidence of acute coronary syndromes. Thiazolidinediones (TZDs), like rosiglitazone, are oral antidiabetic drugs with additional antiinflammatory and potential antiatherogenic properties. In a randomized, placebo-controlled, single-blind trial, we examined the effect of 4 weeks of rosiglitazone therapy on histomorphological characteristics of plaque stability in artery specimen of nondiabetic patients scheduled for elective carotid endarterectomy.

Methods and Results— A total of 24 nondiabetic patients with symptomatic carotid artery stenosis were randomly assigned to rosiglitazone (4 mg BID) or placebo in addition to standard therapy. In this population of nondiabetic patients, rosiglitazone treatment did not significantly change fasting blood glucose, fasting insulin, or lipid parameters. In contrast, rosiglitazone significantly reduced CD4-lymphocyte content as well as macrophage HLA-DR expression in the shoulder region, reflecting less inflammatory activation of these cells by lymphocyte interferon-γ. Moreover, rosiglitazone significantly increased plaque collagen content (7.7±1.6% versus 3.7±0.7% of plaque area; P =0.036) compared with placebo, suggesting that TZD treatment may stabilize arteriosclerotic lesions. In addition, rosiglitazone reduced serum levels of 2 inflammatory arteriosclerosis markers: C-reactive protein and serum amyloid A.

Conclusions— Four weeks of treatment with rosiglitazone significantly reduces vascular inflammation in nondiabetic patients, leading to a more stable type of arteriosclerotic lesion.

Implications of Rosiglitazone and Pioglitazone on Cardiovascular Risk in Patients with Type 2 Diabetes Mellitus

Clinical data suggest that thiazolidinediones--specifically, rosiglitazone and pioglitazone--may improve cardiovascular risk factors through multiple mechanisms. Low insulin sensitivity has been described as an independent risk factor for coronary artery disease and cerebrovascular disease. Patients with insulin resistance often have several known risk factors, such as obesity, dyslipidemia, and hypertension. Other emerging risk factors may be prevalent in patients with insulin resistance, such as hyperinsulinemia, elevated C-reactive protein, elevated plasminogen activator inhibitor levels, and small, dense, low-density lipoproteins. The only available drug class that primarily targets insulin resistance is the thiazolidinediones. These drugs have shown efficacy in affecting surrogate markers of cardiovascular risk in patients with diabetes mellitus. Alterations in these risk factors are likely due to their effects on improving insulin sensitivity and/or glycemic control. Trials to assess whether thiazolidinediones actually reduce cardiovascular outcomes are continuing.

Gelatinases [matrix metalloproteinase-2 (MMP-2) and MMP-9] induce carotid plaque instability but their systemic levels are not predictive of local events

Matrix metalloproteinases (MMPs) appear to play a central role in atherosclerotic plaque remodeling; however, the relationship of increased MMP levels in inducing carotid plaque instability remains controversial. We investigated whether gelatinases (MMP-2 and MMP-9) are implicated in carotid intraplaque hemorrhage and whether their serum levels may predict local carotid events. Nineteen carotid specimens obtained by endarterectomy of 18 patients were studied. The presence of gross intraplaque hemorrhage was recorded before plaque removal and quantification of MMP-2, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) in extracts from (1) the more stenotic area of the plaque, (2) the periphery of the plaque, and (3) serum was performed by enzyme-linked immunosorbent assay. MMP-9 levels measured in extracts from the most stenotic area were significantly higher in patients with intraplaque hemorrhage (p = 0.007); however, serum levels showed no difference, while those taken from the periphery of the lesion were also increased but did not reach a statistically significant level (p = 0.06). An increase in MMP-2 values was observed in the periphery of the lesion (p = 0.04) in patients with intraplaque hemorrhage. TIMP-1 levels showed no difference between the two groups regardless of the presence or absence of intraplaque hemorrhage. No significant differences in MMP levels were observed between symptomatic and asymptomatic patients. Increased levels of MMPs, particularly MMP-9, have been implicated in carotid intraplaque hemorrhage without their serum levels being predictive of local events.

Expression of neutrophil gelatinase-associated lipocalin in atherosclerosis and myocardial infarction

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) modulates the activity of matrix metalloproteinase (MMP) 9, an important mediator of vascular remodeling and plaque instability in atherosclerosis. This study aimed to analyze the expression of NGAL in atherosclerotic plaques and myocardial infarction (MI).

METHODS AND RESULTS

Atherosclerotic apolipoprotein E (apoE)(-/-) x low-density lipoprotein receptor (LDLR)(-/-) and C57BL/6J control mice were exposed to brief hypoxic stress (10 minutes of 10% oxygen). Expression of the mouse NGAL homolog (24p3) and MMP-9 was analyzed 48 hours later by quantitative RT-PCR, immunohistochemistry, and zymography. Hypoxic stress increased NGAL/24p3 mRNA in the cardiac vasculature. NGAL/24p3 was also increased in atherosclerotic plaques of apolipoprotein E(-/-) x LDLR(-/-) mice compared with C57BL/6J mice. Mice developing MI exhibited the highest plaque mRNA expression of NGAL/24p3 and MMP-9. Zymography revealed strong proteolytic activity in areas rich in 24p3 and MMP-9 protein. Immunohistochemistry performed on human carotid endarterectomy specimens and control tissue from the internal mammary artery showed colocalization of MMP-9 and NGAL with macrophages in the atherosclerotic plaques.

CONCLUSIONS

NGAL/24p3 is increased in atherosclerotic plaques and MI. Colocalization with MMP-9 in areas with high-proteolytic activity suggests a role for NGAL/24p3 in modulating the MMP-9-mediated remodeling of plaques and infarcted hearts.

MMP-9 microsatellite polymorphism: Association with the progression of intima-media thickening and constrictive remodeling of carotid atherosclerotic plaques

Intima-media thickening (IMT) of carotid arteries and constrictive remodeling (CR) of atherosclerotic plaques are vascular pathologic characteristics that precede the onset of vascular events. SMC migration and proliferation are linked both to IMT and CR and are matrix metalloproteinase 9 (MMP-9) dependent. A genetic polymorphism (PM) of MMP-9, a CA (13-27) microsatellite in the promoter region, which accounts for differential expression of MMP-9, could be linked to progression of IMT and CR. Progression of IMT and CR of plaques in carotid arteries were studied in 55 consecutive patients with a 12-18 months follow-up. All patients were genotyped for MMP-9 PM. A positive linear relationship between the number of repeats and the progression of IMT (P=0.028) as well as of CR (P=0.018) was found. The analogous relationship was obtained when only the allele with longer microsatellite was considered. Carriers of more than 20 repeats in one allele showed faster both IMT growth (P=0.045) and stenosis progressions of plaques (P=0.019). In multivariate analysis, age, dyslipidemia, and MMP-9 PM were determinants of IMT progression, while MMP-9 PM was the only one of CR. In conclusion, the high number of CA repeats in MMP-9 promoter is positively correlated with faster IMT and CR progression.

Plasma levels and zymographic activities of matrix metalloproteinases 2 and 9 in type II diabetics with peripheral arterial disease

Deregulation of matrix metalloproteinases (MMPs) is an important factor contributing to the development of vascular lesions. Plasma levels and zymographic activities of MMP-2 and MMP-9 were investigated in type II diabetics with (n = 51) or without (n = 42) peripheral artery disease (PAD) and in normal volunteers (n = 23). Plasma MMP-2 levels were higher in type II diabetics with (p < 0.01) or without (p > 0.05) PAD in comparison with normal volunteers. Similarly, type II diabetics with (p < 0.0001) or without (p > 0.05) PAD had higher plasma MMP-9 levels than normal volunteers. Plasma zymographic activities of both MMP-2 and MMP-9 were positively correlated with their plasma levels. Plasma MMP-2 zymographic activity was higher in type II diabetics with PAD than type II diabetics without PAD (p > 0.05). Plasma MMP-9 zymographic activity was higher in type II diabetics with (p < 0.0001) or without (p < 0.0001) PAD in comparision with normal volunteers. Together, these results indicate that increased plasma levels and zymographic activities of MMP-2 and MMP-9 may contribute to PAD in type II diabetics. In particular, plasma MMP-9 may be a useful marker for the development of vascular disease in type II diabetics.

Metalloproteinases and their inhibitors are markers of plaque instability

BACKGROUND

Our aim was to investigate the release, activity, and expression of matrix metalloproteinases (MMPs)-1, -2, -3 and -9, and tissue inhibitors of metalloproteinases (TIMPs)-1 and -2 in patients undergoing carotid endarterectomy and to determine whether altered plasma levels of MMPs and TIMPs may be correlated with carotid instability.

METHODS

The carotid plaques of 53 consecutive patients who underwent carotid endarterectomy were classified histologically as stable or unstable. The release of MMPs and TIMPs was analyzed in the serum of patients with stable and unstable carotid plaques, and in 15 age-matched healthy volunteers. The production, activity, and expression of MMPs and TIMPs were determined by Western blotting, zymography, and reverse transcriptase polymerase chain reaction in the carotid specimens.

RESULTS

Twenty-nine (55%) patients had an unstable carotid plaque and 24 (45%) a stable plaque. Plasma levels of MMPs were higher in patients with unstable plaques compared to patients with stable plaques and healthy volunteers ( P < .001), whereas plasma levels of TIMPs were lower in patients with unstable plaques compared to patients with stable plaques and healthy volunteers ( P < .001). In the carotid specimens, we found increased activity, production, and expression of MMPs, and decreased activity, production and expression of TIMPs in unstable plaques compared to stable plaques ( P < .001). After endarterectomy, plasma levels of MMPs and TIMPs in patients with unstable and stable plaques returned to the values found in healthy volunteers.

CONCLUSIONS

Our study demonstrated that an imbalance exists between MMPs and TIMPs in unstable carotid plaques, which is reflected in the plasma levels of these markers. These data may help in selecting patients at high risk for cerebral events.

Dipyridamole selectively inhibits inflammatory gene expression in platelet-monocyte aggregates

BACKGROUND

Drugs that simultaneously decrease platelet function and inflammation may improve the treatment of cardiovascular disorders. Here, we determined whether dipyridamole and aspirin, a combination therapy used to prevent recurrent stroke, regulates gene expression in platelet-monocyte inflammatory model systems.

METHODS AND RESULTS

Human platelets and monocytes were pretreated with dipyridamole, aspirin, or both inhibitors. The cells were stimulated with thrombin or activated by adhesion to collagen, and gene expression was measured in the target monocytes. Thrombin-stimulated platelets increased monocyte chemotactic protein-1 (MCP-1) expression by monocytes. Dipyridamole but not aspirin attenuated nuclear translocation of NF-kappaB and blocked the synthesis of MCP-1 at the transcriptional level. Dipyridamole delayed maximal synthesis of interleukin-8 but did not alter cyclooxygenase-2 accumulation. Adherence to collagen and platelets also increased the expression of matrix metalloproteinase-9 (MMP-9) in monocytes, a response that was inhibited by dipyridamole. In this case, however, dipyridamole did not block transcription or distribution of MMP-9 mRNA to actively translating polysomes, indicating that it regulates the expression of MMP-9 protein at a postinitiation stage of translation. Dipyridamole also blocked MCP-1 and MMP-9 generated by lipopolysaccharide-treated monocytes, indicating that at least part of its inhibitory action is unrelated to its antiplatelet properties.

CONCLUSIONS

These results indicate that dipyridamole has selective antiinflammatory properties that may contribute to its actions in the secondary prevention of stroke.

The Relationship Between Plasma MMP-1, -7, -8 and -13 Levels and Embolic Potential During Carotid Endoluminal Intervention

BACKGROUND

Patients undergoing carotid endoluminal intervention are at risk of embolic stroke even with the use of distal protection devices. Matrix metalloproteinases (MMPs) have been implicated as a causal factor in plaque instability leading to spontaneous embolisation. We investigated whether plasma MMP levels correlated with the embolisation during carotid endoluminal intervention.

METHODS

Thirty circumferentially intact carotid endarterectomy specimens were subjected to a standardised angioplasty procedure in a pulsatile ex vivo model. Emboli collected in a series of distal filters were counted and sized. Plasma samples were collected pre-operatively and analysed for MMP-7 and MMP-8 levels using Western immunoblotting. MMP-1 and MMP-13 levels were determined using ELISA. Emboli number and maximum size were correlated with plasma levels of the MMPs using Spearmans rank.

RESULTS

Total MMP-8 levels were related to maximum embolus size (r=0.442, p=0.005) but not emboli number (r=0.342, p=0.052). MMP-1, -7 and -13 were not correlated with either emboli number or with maximum embolus size.

CONCLUSION

Pre-operative plasma MMP-8 levels are related to the size of emboli from plaques during carotid endovascular intervention. Further in vivo studies need to be performed to assess the importance of this finding. There is potential for development of plasma markers to identify those patients at greater risk of embolic stroke during carotid endoluminal intervention.

In vitro biomarker discovery for atherosclerosis by proteomics

The purpose of this study was to identify in vitro and then prioritize a tractable set of protein biomarker candidates of atherosclerosis that may eventually be developed to measure the extent, progression, regression, and stability of atherosclerotic lesions. A study was conducted using an in vitro"foam cell" model based on the stimulation of differentiated THP1 cells with oxidized low-density lipoprotein (oxidized LDL) as compared with low-density lipoprotein (LDL). Analysis of the proteins contained in the cell supernatant using proteome scanning technology identified 59 proteins as being increased, 57 with no statistically measurable difference, and 17 decreasing in abundance following treatment with oxidized LDL, as compared with LDL. From the up-regulated list, proteins were prioritized based on their analytical confidence as well as their relevance to atherosclerosis pathways. Within the group of increased abundance, seven families of proteins were of particular interest: fatty acid-binding proteins, chitinase-like enzymes, cyclophilins, cathepsins, proteoglycans, urokinase-type plasminogen activator receptor, and a macrophage scavenger receptor.

Basic fibroblast growth factor mediates carotid plaque instability through metalloproteinase-2 and -9 expression

OBJECTIVE(S)

We hypothesized that basic fibroblast growth factor (bFGF) may exert a role in carotid plaque instability by regulating the expression of matrix metalloproteinases (MMP).

METHODS

Plaques obtained from 40 consecutive patients undergoing carotid endarterectomy were preoperatively classified as soft or hard. Serum bFGF was pre- and postoperatively measured. The release of MMP-2 and MMP-9 in the blood serum, and the activity, production and expression in the carotid specimens was analyzed. Specific anti-bFGF inhibition tests were performed in vitro on human umbilical artery smooth muscle cells (HUASMC) to evaluate the role of bFGF in the activity, production and expression of MMP-2 and -9.

RESULTS

Twenty-one (53%) patients had a soft carotid plaque and 19 (48%) a hard plaque. Preoperative bFGF serum levels were higher in patients with soft plaques [soft=34 (28-39) pg/mL and hard=20 (17-22) pg/mL-p<0.001] and postoperatively returned to normal values (when compared to 10 healthy volunteers). The serum levels of MMP-2 in patients' with soft plaques were higher than those in patients' with hard plaques [soft=1222 (1190-1252) ng/mL and hard=748 (656-793)ng/mL-p<0.0001]. MMP-9 serum values were 26 (22-29) ng/mL for soft plaques and 18 (15-21) ng/mL for hard plaques (p<0.0001). We found increased activity, production and expression of MMP-2 and -9 in soft plaques compared to hard plaques (p<0.001). In vitro inhibition tests on HUASMC showed the direct influence of bFGF on the activity, production and expression of MMP-2 and -9 (p<0.001).

CONCLUSIONS

bFGF seems to exert a key role in carotid plaque instability regulating the activity, production and expression of MMP thus altering the physiologic homeostasis of the carotid plaque.

Serum values of metalloproteinase-2 and metalloproteinase-9 as related to unstable plaque and inflammatory cells in patients with greater than 70% carotid artery stenosis

OBJECTIVE

Unstable carotid plaques, characterized by increased levels of macrophages and T lymphocytes, have high emboligenic potential and carry a risk for producing cerebral ischemic events. It has been suggested that plaque instability may be mediated by the family of metalloproteinases (MMPs). The purpose of this study was to analyze the relationship between concentrations of MMP-2 and MMP-9 and unstable carotid plaques, presence of macrophages and T-lymphocytes in the plaques, and neurologic symptoms, to establish additional risk markers in patients with greater than 70% carotid artery stenosis. This was a cross-sectional study carried out in a referral center and institutional practice in hospitalized patients.

METHODS

The study included 40 patients with carotid artery stenosis treated with carotid endarterectomy. Of these patients, 67.5% had experienced a previous neurologic event and 32.5% exhibited no symptoms. MMP-2 and MMP-9 levels were determined with enzyme-linked immunosorbent assay 48 hours before surgery. Histopathologic analysis (stable or unstable) and immunohistochemistry (macrophage count, T lymphocytes, activated T lymphocytes) were carried out on the plaques.

RESULTS

Mean MMP-2 and MMP-9 serum concentrations in the population studied were 1138.27 +/- 326.08 ng/mL and 1026.10 +/- 412.90 ng/mL, respectively. MMP-2 levels were significantly higher in patients with symptoms compared with patients without symptoms (1247.30 +/- 276.80 ng/mL vs 911.80 +/- 311.84 ng/mL; P =.001). MMP-9 was also significantly higher in the symptomatic group (1026.10 +/- 412.90 ng/mL vs 377.84 +/- 164.08 ng/mL; P =.001) and in patients with unstable plaques compared with those with stable plaques (1006.98 +/- 447.09 ng/mL vs 496.16 +/- 292.78 ng/mL; P =.001). In addition, we found a strong association between elevated MMP-9 concentration and presence of macrophages in plaque (Spearman rho, 0.45; P =.004). At logistic regression analysis, variables that best predicted the presence of unstable plaque were a previous neurologic event and MMP-9 level greater than 607 ng/mL (sensitivity, 96%; specificity, 92%; negative predictive value, 94.7%; positive predictive value, 93%).

CONCLUSION

Elevated MMP-9 concentration is associated with carotid plaque instability and the presence of macrophages, factors that indicate increased risk for a neurological event. Determination of this gelatinase may enable identification of high-risk subgroups of patients with carotid artery stenosis.

Relationship of Matrix Metalloproteinases and Macrophages to Embolization During Endoluminal Carotid Interventions

PURPOSE

To investigate if relationships exist among macrophage infiltration, plasma matrix metalloproteinase (MMP) levels, and the number of emboli generated during endoluminal carotid interventions.

METHODS

Carotid endarterectomy specimens excised as intact cylinders (n=27) were subjected to a standardized angioplasty procedure under radiological guidance in an ex vivo pulsatile flow model. Emboli collected in distal filters were counted and sized using microscopy. Preoperative plasma gelatinase activity was determined by gelatin zymography and quantified using image analysis software. Levels of tissue inhibitors of metalloproteinases (TIMP) 1 and 2 were determined by ELISA. Macrophages within postangioplasty plaques were analyzed using immunohistochemical staining for CD68 antigen and graded by a blinded examiner. Statistical analysis was performed using Spearman's rank correlation.

RESULTS

The median number of emboli recorded during angioplasty was 104 (interquartile range 33.75-242.5, absolute range 13-1090). Plasma MMP-9 and MMP-2 levels correlated with emboli number (r=0.544 [p=0.003] and r=0.412, [p=0.033], respectively), while TIMP-1 and TIMP-2 levels did not. Macrophage infiltration within the plaques correlated with emboli number (r=0.722, p<0.001) and the plasma MMP-9 level (r=0.489, p=0.010).

CONCLUSIONS

These data indicate that plaque macrophage infiltration may play a role in the generation of emboli during endoluminal carotid intervention, possibly via modulation of protease activity.

Plasma matrix metalloproteinases, low density lipoprotein oxidisability and soluble adhesion molecules after a glucose load in Type 2 diabetes

Background

Acute hyperglycaemia is an independent cardiovascular risk factor in Type 2 diabetes which may be mediated through increased oxidative damage to plasma low density lipoprotein, and in vitro, high glucose concentrations promote proatherogenic adhesion molecule expression and matrix metalloproteinase expression.

Methods

We examined these atherogenic risk markers in 21 subjects with Type 2 diabetes and 20 controls during an oral 75 g glucose tolerance test. Plasma soluble adhesion molecule concentrations [E-selectin, VCAM-1 and ICAM-1], plasma matrix metalloproteinases [MMP-3 and 9] and plasma LDL oxidisability were measured at 30 minute intervals.

Results

In the diabetes group, the concentrations of all plasma soluble adhesion molecules fell promptly [all p < 0.0001] related principally to glycaemic excursions, but such changes also occurred in the control group. Plasma MMP-3 and -9 concentrations were lower [p < 0.05], and LDL oxidisability greater [p < 0.01] in the diabetes group but did not change in either group. There was a direct relationship between plasma MMP-9 and s ICAM-1 in the controls [r = 0.62; p = 0.006] perhaps suggesting a functional relationship between s ICAM-1 shedding and MMP-9.

Conclusions

A glucose load leads to a rapid fall in plasma soluble adhesion molecule concentrations in Type 2 diabetes and controls, perhaps reflecting reduced generation of soluble from membrane forms during enhanced leukocyte – endothelial adhesion or increased hepatic clearance, without changes in plasma matrix metalloproteinase concentrations or low density lipoprotein oxidisability. These in vivo findings are in contrast with in vitro data.

Growth hormone replacement decreases plasma levels of matrix metalloproteinases (2 and 9) and vascular endothelial growth factor in growth hormone-deficient individuals

BACKGROUND

Matrix metalloproteinases (MMP) are implicated in cardiovascular disease. Growth hormone (GH) deficiency is associated with increased cardiovascular mortality. We assessed whether GH replacement, in GH-deficient adults, has any effect on plasma levels of MMP-2 and MMP-9 and on vascular endothelial growth factor (VEGF), known to activate MMPs.

METHODS AND RESULTS

The study comprised 66 GH-deficient adults, 37.8+/-14.7 years of age (37 female). Plasma MMP-2 and MMP-9, VEGF, and insulin-like growth factor-1 (IGF-1) were measured at baseline (V1), at 12 months (V2), and at 24 months of GH treatment (V3). IGF-1 levels rose under GH replacement (mean+/-SD): V1, 151.6+/-91.9 microg/mL; V2, 270.2+/-114.8 microg/mL; and V3, 266.2+/-109.8 (V1 versus V2; P<0.001: V2 versus V3; P=0.76). MMP-9 exhibited the most pronounced and sustained decline from 1248.0+/-651.1 ng/mL at V1, 949.2+/-457.7 ng/mL at V2, and 760.8+/-386.1 ng/mL at V3 (P<0.001 at all time points). A similar pattern was detected for VEGF levels: 358.5+/-209.0 pg/mL at V1, 310.6+/-225.7 pg/mL at V2 (P<0.001), and 283.7+/-202.7 pg/mL at V3 (V2 versus V3; P=0.005). MMP-2 demonstrated a significant decline initially from V1 to V2 (1134.4+/-217.8 ng/mL versus 1074.5+/-203.0 ng/mL, respectively; P=0.031), reaching a plateau at V3 (1072.3+/-220.2 ng/mL) (V2 versus V3; P=0.93). A negative relation existed between MMP-9 versus IGF-1 and MMP-2 versus IGF-1 (P<0.001 and P=0.007, respectively) as well as between VEGF and IGF-1 (P<0.001).

CONCLUSIONS

These changes in MMPs and VEGF may contribute to the anticipated reduction in vascular mortality in hypopituitary adults receiving GH replacement.

Elevation in Plasma MMP-9 Following Carotid Endarterectomy is Associated with Particulate Cerebral Embolisation

OBJECTIVES

To study plasma MMP-9 levels before and after carotid endarterectomy (CEA).

DESIGN

Observational study.

METHODS

Pre-operative (morning of surgery) and post-operative (48 h) plasma samples were obtained from 75 consecutive patients undergoing CEA. MMP-9 concentrations were quantified using ELISA. Transcranial Doppler monitoring was performed on each patient to detect particulate embolisation during the dissection phase of the CEA, until the application of carotid clamps.

RESULTS

The median post-operative plasma MMP-9 level of emboli-positive patients was significantly higher than their median pre-operative value (14.9 ng/ml vs. 8.8 ng/ml; p=0.038). However, no significant difference was seen in the plasma MMP-9 level of emboli-negative patients (7.7 ng/ml vs. 7.1 ng/ml; p=0.364). A greater rise was seen in the median plasma MMP-9 levels of those patients suffering >2 emboli (from 3.4 to 19.3 ng/ml; p=0.041) than those patients suffering 1 or 2 emboli (from 10.1 to 12.8 ng/ml; p=0.340).

CONCLUSIONS

Plasma MMP-9 only rises after CEA in patients with evidence of embolisation. This increase is more pronounced in those with high numbers of emboli. These data suggest that the increase in MMP-9 is due to cerebral damage caused by embolisation.