Circulating Matrix Metalloproteinase-9 Research Articles

Association of Circulating Matrix Metalloproteinase-9 and the Risk of Coronary Heart Disease in Young Smokers

Introduction: Smoking causes cardiovascular risk which may alter the stability between the production and degradation of the extracellular matrix. Matrix metalloproteinase-9 (MMP-9) is a zinc-containing endopeptidase that degrades the extracellular matrix and plays a vital role in tissue remodeling. As a result, elevated serum MMP-9 levels produced by smoking, particularly at young age, raise the risk of future CHD. So this study aims to find out the possible relationship between circulating MMP-9 and the risk of cardiovascular disease in young smokers. Methods: The study was conducted on smokers with CHD subjects attending cardiology and medicine OP of the SRM Medical College Hospital and research center Tamil Nadu, India. The study group was divided into three groups. Group 1 includes 120 healthy controls as nonsmokers, Group 2 includes 120 smokers with Coronary heart disease (CHD), and Group 3 includes 120 smokers with diabetes and CHD subjects in the age group of 20-55 years. Serum MMP-9, hs-CRP, and APO-E levels were measured using the ELISA method and the lipid level was measured enzymatically using AU480 automatic analyzer (back man coulter). Results: The mean serum MMP-9, hs-CRP, and APO-E levels were significantly higher in both groups (p<0.05) when compared to controls. The study also shows a significant positive association between MMP-9 with hs-CRP, APO-E, smoking burden, and smoking intensity. Conclusion: The study concludes a significant association exists between cigarette smoking with MMP-9 and also relative exposure to circulating inflammation markers plays a potential role in the pathogenesis of CHD.

Biomarkers predict hemorrhagic transformation and stroke severity after acute ischemic stroke

ObjectivesHemorrhagic transformation (HT) is a complication occurring in patients with acute ischemic stroke (AIS) either spontaneously or post-thrombolysis leading to significant morbidity and mortality. We assessed circulating matrix metalloproteinase-9 (MMP-9), Claudin-5, and soluble serum stimulation-2 (sST2) in HT and stroke severity in AIS based on their temporal distribution. Materials and methodsWe prospectively enrolled 111 AIS patients within 12 h from onset. Patient demographic, clinical, and imaging details were documented. Follow-up imaging was conducted 24–48 h after admission. Blood samples were taken at three time-points from stroke onset. HT was classified according to the European Co-operative Acute Stroke Study-III(ECASS-III). Stroke severity was assessed using the National Institutes of Health Stroke Scale (NIHSS). Multiple logistic regression and receiver operating characteristic curve were conducted to determine the discriminative capacity. ResultsMean age was 62.3 ± 11.7 years and median baseline NIHSS was 12[IQR 8.0–18.0]. HT was detected in 30(27%) patients. Biomarker levels at 12 h were elevated with median MMP-9 concentration of 153.9 ng/mL[IQR 110.6–309 ng/mL] indicating a trend toward significant positive correlation with HT(P = 0.05). Claudin-5 levels at 12 h was elevated but was not statistically significant (43.1 pg/mL[IQR:26.7–72.6 pg/mL] vs 59.4 pg/mL[IQR:24.5–100.8 pg/mL];P = 0.4). Multiple logistic regression indicated Claudin-5 levels at 12 h (OR 9.46;95% CI:1.97–64.6;P = 0.010) and baseline low ASPECTS score(OR 20.3;95% CI:3.46–193; P = 0.003) independently predicted HT. MMP-9 at 12 h was significantly elevated in patients with moderate to severe strokes (P = 0.04). ConclusionsClaudin-5 and low ASPECTS independently predicted HT. MMP-9 was positively correlated with baseline stroke severity.

Metformin mediates MicroRNA-21 regulated circulating matrix metalloproteinase-9 in diabetic nephropathy: an in-silico and clinical study

Metformin is commonly used as an oral hypoglycaemic agent in type 2 diabetes mellitus (T2DM). MicroRNA-21 is widely studied in diabetic and diabetic nephropathy (DN) patients. Matrix metalloproteinase-9 (MMP9) is involved in extracellular matrix degradation and tissue repair processes. However, the effect of metformin administration on hsa-miR-21-5p and MMP9 has not been evaluated in T2DM and DN patients. The study subjects were divided into three groups (Healthy controls = 36, T2DM = 38, DN = 35). Anthropometric measurements were taken and biochemical tests were carried out on fasting blood samples. Reverse transcriptase PCR was employed for whole blood gene expression analysis of hsa-miR-21-5p and MMP9. Bioinformatics analyses including drug-gene interaction, protein-protein interaction, functional enrichment analyses and co-expression networks were performed. In the present study, MMP9 and hsa-miR-21-5p levels were downregulated and upregulated respectively in T2DM and DN patients when compared with healthy controls. However, in metformin-treated group, a downregulation of hsa-miR-21-5p and upregulation of MMP9 was observed. In-silico analysis revealed the target genes involved in the miR-21 and MMP9 interaction network. Metformin directly targets miR-21 and regulates MMP9 expression in T2DM patients, influencing the pathogenesis of DN. Highlights MMP-9 and hsa-miR-21-5p were downregulated and upregulated respectively in T2DM and DN patients in a Western Indian population. The patients treated with metformin showed downregulation of hsa-miR-21-5p and upregulation of MMP9. In-silico analysis revealed MMP-9 as well as PTEN to be targets of hsa-miR-21-5p. Metformin regulates MMP9 expression in T2DM and DN patient populations through hsa-miR-21-5p.

MPO G-463A Gene Polymorphism and Circulating Matrix Metalloproteinase-9, Myeloperoxidase Levels in Coronary Artery Disease Patients

Objective: Coronary artery disease(CAD) patients living in Elazığ region is to assess the levels of matrix metalloproteinase-9(MMP-9) and myeloperoxidase(MPO), polymorphisms MPO gene. Research Design and Methods: Eighty-eight patients with angiographically diagnosed coronary artery disease between the ages of 18-80 who applied to Department of Cardiology, Faculty of Medicine, Firat University were enrolled in this study. MPO, MMP-9 levels in plasma samples of individuals were determined by enzyme-linked immuno sorbent assay (ELISA) according to the kit procedure. MPO polymorphism was studied using the PCR-RFLP technique. Results: When plasma MPO and MMP-9 levels were compared in the control and CAD groups; MPO levels were statistically significant (p <0.05). MMP-9 levels were not statistically significant. MPO gene polymorphism was not found statistically significant in CAD. Conclusion: MPO gene polymorphism is thought to be associated with greater population populations in CAD and may be used in the future as a biomarker for plasma MPO enzyme levels in CAD. Key words: MPO, coronary artery disease, MMP-9 DOI: 10.7176/JHMN/83-02

Circulating Matrix Metalloproteinase-9 Levels in Patients with Systemic Lupus Erythematosus: A Meta-analysis.

Matrix metalloproteinase-9 (MMP-9) is closely related to the pathogenesis of autoimmune diseases, especially Systemic Lupus Erythematosus (SLE). However, published works about the circulating MMP-9 levels in SLE are contradictory. A meta-analysis was performed to estimate circulating MMP- 9 levels in SLE patients more accurately and explore its related influencing factors. The related literatures were systematically searched in PubMed, Embase, and The Cochrane Library database (up to 31 January 2018). Pooled Standardized Mean Difference (SMD) and 95% Confidence Interval (CI) of circulating MMP-9 levels were calculated by Stata12.0 software according to fixed-effect or randomeffect model analysis. A total of 638 articles were retrieved, and 12 studies including 730 SLE cases and 759 controls were finally included in the meta-analysis. No significant differences in circulating MMP-9 levels were observed between SLE patients and healthy controls (pooled SMD = -0.209, 95% CI = -0.812 to 0.394). However, subgroup analyses indicated that age<30 years group had higher MMP-9 levels (SMD = 0.991, 95% CI: 0.504 to 1.478) and sample size (n ≥ 60) group had lower MMP-9 levels when compared with controls (SMD = -0.755, 95% CI: - 1.347 to -0.163). The meta-analysis of current evidence suggests that circulating MMP-9 levels do not differ between SLE patients and healthy controls, however, the results may be affected by age and sample size. Further studies are needed to clarify the relationship between SLE and circulating MMP-9 levels.

Circulating Matrix Metalloproteinase-9 Level Is Associated with Cerebral White Matter Hyperintensities in Non-Stroke Individuals

Backgrounds: The pathogenesis of cerebral white matter hyperintensities (WMH) has been poorly understood. Our aim was to investigate the association of circulating proteins, the biomarkers of inflammation, blood-brain barrier (BBB) dysfunction, and thrombosis with WMH in non-stroke individuals. Methods: Demographic, laboratory, and brain magnetic resonance imaging parameters were prospectively analyzed in 137 subjects. The relationship between plasma interleukin-6, tumor necrosis factor-α, matrx-metalloproteinase-9 (MMP-9), plasminogen activator inhibitor-1 and overt WMH (Fazekas grading score ≥2) was analyzed. Results: In univariate analysis, old age, high blood pressure, history of hypertension, and elevated plasma MMP-9 level were associated with overt WMH. In multivariate analysis, plasma MMP-9 still maintained a significant association with WMH. Plasma MMP-9 level was weakly but significantly associated with WMH volume (r = 0.232, p = 0.006). All the other circulating proteins examined failed to demonstrate a significant relationship with WMH. Conclusions: Plasma MMP-9 is associated with pathophysiology of WMH development.

Significance of circulating matrix metalloproteinase-9 to tissue inhibitor of metalloproteinases-2 ratio as a predictor of disease progression in patients with metastatic renal cell carcinoma receiving sunitinib

ObjectivesTo assess the significance of circulating matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) as predictors of disease progression in patients with metastatic renal cell carcinoma (mRCC) receiving sunitinib. Materials and methodsCirculating levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 in sera from 52 patients with mRCC treated with sunitinib were measured at the baseline and on the first day of each treatment cycle until progression using enzyme-linked immunosorbent assays. ResultsThe baseline level of MMP-9 in nonresponders to sunitinib was significantly higher than that in responders, whereas the baseline level of TIMP-2 in nonresponders was significantly lower than that in responders. However, there were no significant differences in the serum levels of MMP-2 and TIMP-1 between responders and nonresponders. The serum MMP-9/TIMP-2 ratio at the baseline in nonresponders was also significantly higher than that in responders. Univariate analysis showed that the MMP-9/TIMP-2 ratio, but not MMP-9 and TIMP-2 levels, was significantly correlated with progression-free survival, and the MMP-9/TIMP-2 ratio, in addition to the Memorial Sloan-Kettering Cancer Center classification and C-reactive protein level, appeared to be independently associated with progression-free survival on multivariate analysis. Furthermore, despite the lack of significant differences in the serum levels of MMP-9 and TIMP-2 between the baseline and the time of progression, the MMP-9/TIMP-2 ratio at the time of progression was significantly elevated compared with the baseline ratio. ConclusionsAn imbalance between the serum MMP-9 and TIMP-2 levels could be a novel biomarker to predict disease progression in patients with mRCC under treatment with sunitinib.

Predicted value of circulating matrix metalloproteinase-9 in arteria hypertension patients after acute ischemic stroke

The aim of the study was to investigate the predictive value of circulating matrix metalloproteinase-9 (MMP-9) in hypertensive patients after acute ischemic stroke. Methods. 102 patients with mild to moderate arterial hypertension within 3 weeks after acute ischemic stroke were included in the study. Follow-up was 12 months with a 3 month intervals. The circulating MMP-9 level was assessed at baseline.

Morphine and breast tumor metastasis: the role of matrix-degrading enzymes

Opioids including morphine are commonly used in pain management during and after cancer surgery but have been linked to a variety of pro- and anti-tumor effects. In the present study the effect of morphine administration on the localization and growth of breast tumor cells in lungs and the level of extracellular matrix (ECM) proteases were investigated. In a mouse syngeneic model of intravenously inoculated breast cancer cells, morphine administration led to a reduction in the localization and growth of tumors in the lungs and a reduction in circulating matrix metalloproteinase-9 (MMP-9) and urokinase-like plasminogen activator (uPA). To model the involvement of non-malignant cells of the tumor microenvironment in the changes we observed in the level of proteases, we co-cultured breast cancer cells with macrophages, endothelial cells and fibroblasts. We found a significant elevation of matrix proteases as well as matrix protease inhibitors in co-cultures of breast cancer cells with macrophages or endothelial cells. Interestingly, morphine treatment of these co-cultures reduced the level of MMP-9 and increased its endogenous inhibitor, TIMP-1, thereby altering the proteolytic profile. Morphine affected the level of enzymes in co-cultures but not in cells grown individually. This suggests that anti-tumor effects of morphine observed in our in vivo model could be mediated at least in part through modulation of paracrine communication between cancer cells and non-malignant cells in the tumor microenvironment.

Interrelationship of Circulating Matrix Metalloproteinase-9, TNF-α, and OPG/RANK/RANKL Systems in COPD Patients with Osteoporosis

Previous studies have shown that matrix metalloproteinase-9 (MMP-9) and its cognate inhibitor TIMP-1, inflammatory cytokine TNF-α, and the OPG/RANK/RANKL system may each play individual roles in the pathogenesis of osteoporosis in patients with COPD. In the present study, we investigated the interrelationships of these factors in male COPD patients with and without osteoporosis. The serum levels of MMP-9, MMP-9/TIMP-1 ratio, TNF-α, RANKL, OPG, and the RANKL/OPG ratio were higher in COPD patients with osteoporosis than in individuals with normal or low bone mineral density (BMD) (N = 30, all P < 0.05 or < 0.01). The lung function FEV1%Pre and the BMD of the lumbar spine and femoral neck were found to be negatively correlated with MMP-9 serum level (r = −0.36, P < 0.05, r = −0.58, P < 0.001, and r = −0.62, P < 0.01, respectively), RANKL serum level (r = −0.21, P < 0.05, and r = −0.25, P < 0.05, and r = −0.26, P < 0.05, respectively), and RANKL/OPG ratio (r = −0.23, P < 0.05, r = −0.33, P < 0.05, and r = −0.38, P < 0.05, respectively). However, they had no correlation with TIMP-1, TNF-α, OPG, or RANK. The MMP-9 serum level was found to be positively correlated with TNF-α level (r = 0.35, P < 0.05) and RANKL/OPG ratio (r = 0.27, P < 0.05) but not associated with RANKL. These results suggest that MMP-9, TNF-α, and the OPG/RANK/RANKL system may be closely interrelated and may play interactive roles in pathogenesis of osteoporosis in COPD.

Circulating MMP-9 during exercise in humans

Matrix metalloproteinase 9 (MMP-9) is a member of a family of zinc-dependent endopeptidases capable of degrading extracellular matrix (ECM) proteins. A single bout of exercise increases levels of activated MMP-9 in skeletal muscle and in the circulation. However, whether the exercise-induced activation of MMP-9 is associated with ECM remodeling and the cellular source behind MMP-9 in the circulation is not known. In the present study ten healthy male subjects performed a single cycle exercise bout and arterial and venous femoral blood was collected. To test if exercise induces basal lamina degradation and if circulating levels of MMP-9 is related to a release from the exercising muscle, arteriovenous differences of collagen IV and MMP-9 were measured by ELISA and zymography, respectively. Furthermore, markers of neutrophil degranulation elastase and neutrophil gelatinase-associated lipocalin (NGAL) were measured by ELISA. Plasma levels of collagen IV increased during the exercise bout and an increased arteriovenous difference of collagen IV was noted at 27 min of exercise. Plasma levels of MMP-9 were increased at both 27 and 57 min of exercise but no arteriovenous difference was noted. No changes over time were detected for elastase and NGAL. The observed release of collagen IV from the exercising muscle indicate basal lamina turnover following a single bout of exercise. No detectable release of MMP-9 was observed, suggesting that the increase in plasma MMP-9 could come from a source other than the skeletal muscle.

Circulating Matrix Metalloproteinase-9 in Chronic Heart Failure Patients Correlated With the Severity of Heart Failure and Outcome

Background: Matrix metalloproteinase (MMP) activity are upregulated in the failing heart, and have been demonstrated to influence ventricular remodeling. This study examined whether circulating MMPs are related to the prognosis of chronic heart failure (CHF) and the correlations between circulating MMP-9 levels and other biomarkers in CHF patients. Methods: Serum samples were obtained from 173 consecutive patients with CHF (Average age was 64.8±11.4, LVEF<50%, New York Heart Association (NYHA) class I-IV), and analyzed circulating levels of MMP-9, tissue inhibitors of MMP-1 (TIMP-1), norepinephrine (NE), A-type natriuretic peptides, B-type natriuretic peptides, and cytokines (interleukin (IL)-6 and tumor necrosis factor-alpha (TNF- alpha).

Validating Sampling Methods for Measurement of Circulating Matrix Metalloproteinase-9 and Tissue Inhibitor of Metalloproteinase-1

Zhang, Ru-Yuan MD, PhD; Cui, Wei MD, PhD; Zhao, Kai-Jun MD; Tang, Yao-Qing MD, PhD; Li, Lei MD Author Information

Elevated levels of circulating matrix metalloproteinase-9 are associated with a dysregulated cortisol rhythm—A case-control study of coronary artery disease

A dysregulated cortisol pattern has been found to be associated with systemic inflammatory activity in patients with coronary artery disease (CAD). Matrix metalloproteinase (MMP)-9 is involved in both inflammation and matrix degradation and considered a main contributor to coronary plaque rupture. In this study, we hypothesized that a dysfunctional cortisol response also involved a failure to regulate systemic MMP-9 levels in CAD patients. Total MMP-9, active MMP-9 and the endogenous inhibitor TIMP-1 were measured in 30 CAD patients and 30 healthy controls. Morning and evening cortisol was measured in repeated saliva samples. Patients had higher levels of total and active MMP-9 (both p<0.01) and increased 24-h cortisol output (p<0.05) characterized by higher levels of evening cortisol (p=0.011). MMP-9 was associated with evening cortisol (p<0.001) independent of smoking and inflammatory markers. Compared with controls, patients also showed a blunted cortisol response to stress. After stress, the levels of MMP-9 became significantly reduced in controls whereas they remained unchanged in patients. The data indicate that MMP-9 is differently regulated in patients due to a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and emphasize the role of MMP-9 as a possible link between stress and cardiovascular disease.

Increases in circulating matrix metalloproteinase-9 levels following fibrinolysis for acute pulmonary embolism

Introduction Fibrinolyis is one of the first line therapies in high risk pulmonary embolism (PE) according to current guidelines. Previous studies showed that fibrinolytic therapy with tPA (tissue plasminogen activator, or alteplase) upregulates the concentrations of matrix metalloproteinases (MMPs) and contributes to hemorrhagic transformation after cardioembolic stroke. However, no previous study has described the circulating MMPs levels following fibrinolysis for acute PE. Materials and Methods We serially measured the circulating levels of MMPs (MMP-9 and MMP-2) and their endogenous inhibitors, the tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in alteplase and in streptokinase-treated patients with acute PE by gelatin zymography and by enzyme-linked immunosorbent assays, respectively. Results We found that therapy of PE streptokinase or with alteplase is associated increased pro-MMP-9, but not MMP-2, concentrations for up to 24 hours, whereas no significant changes were found in TIMP-1 or TIMP-2 concentrations. This alteration returned to normal 3 to 5 days after thrombolysis. This is the first study reporting on MMPs alterations following fibrinolysis for acute PE. Conclusions We found transient increases in circulating pro-MMP-9 levels following fibrinolysis for acute PE. Our findings support the hypothesis that increased MMP-9 levels may underlie the risk of intracerebral hemorrhage or other bleeding complication of thrombolysis for acute PE, and the use of MMP inhibitors may decrease such risk.

Circulating matrix metalloproteinase-9 concentrations and abdominal aortic aneurysm presence: a meta-analysis

To summarize the present evidence for an association between matrix metalloproteinase-9 (MMP-9) and abdominal aortic aneurysm (AAA) presence, we performed a meta-analysis of case-control studies that compared circulating MMP-9 concentrations between patients with AAA and subjects without AAA. MEDLINE database was searched to identify all case-control studies. For each study, data regarding serum or plasma MMP-9 concentrations in both the AAA and control groups were used to generate standardized mean differences (SMDs) and 95% confidence intervals (CIs). Study-specific estimates were combined using inverse variance-weighted average of logarithmic SMDs in both fixed- and random-effects models. Our search identified eight eligible studies including 580 patients with AAA and 258 subjects without AAA. Pooled analysis demonstrated significantly higher circulating MMP-9 concentrations in the AAA group than those in the control group in random-effect models (SMD, 0.70; 95% CI, 0.23-1.17; P=0.004). There was significant study heterogeneity of results (P<0.00001) but no evidence of significant publication bias (P=0.1376). We found that, based on a systematic review and meta-analysis, circulating MMP-9 concentrations are higher in patients with AAA than those in subjects without AAA. Higher circulating MMP-9 concentrations are associated with AAA presence.

Hyperandrogenism is related to the circulating matrix metalloproteinase-9 response to hyperglycemia in women with polycystic ovary syndrome

OBJECTIVE: Hyperglycemia stimulates proatherogenic inflammation in Polycystic Ovary Syndrome (PCOS). Matrix Metalloproteinase-9 (MMP-9) secreted by leukocytes is a promoter of atherosclerotic plaque rupture. We examined the effect of in vivo glucose challenge on circulating MMP-9 levels in women with PCOS compared to ovulatory controls, and the relationship of this effect with LH and androgens. DESIGN: Prospective, controlled study MATERIALS AND METHODS: Twelve women with PCOS (6 lean, 6 obese) between ages 18-40, diagnosed on the basis of oligo- or amenorrhea and hyperandrogenemia, and 12 ovulatory controls (6 lean, 6 obese) of similar age were selected for study. Subjects with diabetes, inflammatory illnesses or other endocrinopathies were excluded. A 2-hour glucose tolerance test was performed within 5-8 days of menses. MMP-9 levels were measured by ELISA in plasma from blood samples drawn fasting (pre) and 2 hours after (post) glucose ingestion. Levels of LH, testosterone and androstenedione were measured in serum by RIA. RESULTS: There were no significant differences in age and body mass index in women with PCOS compared to weight-matched controls. The percent change in the mean concentration of MMP-9 between the pre - and post-glucose challenge samples of lean and obese women with PCOS (55.6±22.3%; 81.2±17.0%) was significantly higher (p<0.02) compared to that of lean and obese controls which decreased (-4.9±5.4%; -35.1±13.1%). The MMP-9 response was positively correlated with serum levels of LH (r=0.49; p<0.02), testosterone (r=0.73; p<0.0001) and androstenedione (r=0.76; p<0.0001). CONCLUSIONS: These preliminary data indicate that in response to hyperglycemia, circulating MMP-9 levels are increased in women with PCOS, independent of obesity. Hyperandrogenism may perpetuate this proinflammatory, proatherogenic phenomenon in PCOS.

Circulating matrix metalloproteinase-9 and osteoporosis in patients with chronic obstructive pulmonary disease

Matrix metalloproteinase-9 (MMP-9) has been implicated in airways injury in chronic obstructive pulmonary disease (COPD). Osteoporosis is common in patients with COPD, and MMP-9 is an indicator of activated osteoclasts. We hypothesized that circulating MMP-9 would be related to bone mineral density (BMD) in COPD. We explored the relationship between MMP-9, tissue inhibitors of metalloproteinases (TIMP)-1 and -2, and BMD status in patients with COPD. A total of 70 clinically stable patients with confirmed COPD and 39 control subjects underwent spirometry, dual-energy x-ray absorptiometry to determine BMD, and venous sampling for measurement of cytokines and MMP-9 and TIMP-1 and -2. In patients, circulating MMP-9 was increased: mean (SD) 38.5 (2.2) compared with control subjects 20.1 (2.0) ng/mL, P < 0.001, whereas TIMP-1 and -2 were not different. In the patients, MMP-9 was greater in those with osteoporosis, compared with those with osteopenia, no bone disease or control subjects, and patients with osteopenia had greater MMP-9 than control subjects. The adjusted receiver operating characteristics curve area for MMP-9 detecting osteoporosis was 0.86. Patients had elevated systemic inflammatory mediators compared with control subjects, but these were unrelated to bone status. Increased circulating MMP-9 in patients with COPD was related to the presence of osteoporosis and not to lung function. MMP-9 may be a biomarker of increased bone resorption.

Nitrite or sildenafil, but not BAY 41-2272, blunt acute pulmonary embolism-induced increases in circulating matrix metalloproteinase-9 and oxidative stress

Introduction Inhibition of matrix metalloproteinases (MMPs) improves the hemodynamics during acute pulmonary embolism (APE) and oxidative stress upregulates MMPs. We compared the effects of different NO-cGMP pathway activators on APE-induced increases in MMPs. Materials and Methods Hemodynamic and biochemical evaluations were performed in non-embolized dogs treated with saline (N = 5), and in microspheres embolized dogs receiving saline (n = 9), or nitrite (6.75 µmol/kg i.v. over 15 min followed by 0.28 µmol/kg/min; n = 5), or sildenafil (0.25 mg/kg; n = 5), or BAY 41-2272 (0.03, 0.1, 0.3, and 1 mg/kg/h; n = 5). Plasma thiobarbituric acid reactive substances (TBARS) concentrations were determined. Zymograms of plasma samples were performed, and in vitro antioxidant effects or inhibition of MMPs by these drugs were examined. Results APE increased mean pulmonary artery pressure by ~ 25 mmHg. Nitrite, BAY 41-2272, or sildenafil reversed this increase by ~ 40% (P < 0.05). Similar effects were seen on the pulmonary vascular resistance. While both nitrite and sildenafil produced no systemic effects, the highest dose of BAY 41-2272 produced systemic hypotension (P < 0.05). While nitrite and sildenafil blunted the increases in plasma pro-MMP-9 levels and TBARS (all P < 0.05), BAY 41-2272 produced no such effects. Nitrite and sildenafil produced in vitro antioxidant effects and inhibited MMPs only at high concentrations. BAY 41-2272 produced no such effects. Conclusions Activation of the NO-cGMP pathway with nitrite or sildenafil, but not with BAY 41-2272, attenuates APE-induced oxidative stress and increased MMP-9 levels. These findings are consistent with the idea that NO-cGMP pathway activators with antioxidant effects prevent the release of MMP-9 during APE.

Adipose tissue is not an important source for matrix metalloproteinase-9 in the circulation

Objectives: Matrix metalloproteinase 9 (MMP-9) is overexpressed in atherosclerotic plaques and in many cancers, and has emerged as a potential circulating biomarker for such diseases. However, adipose tissue (AT) might also produce circulating MMP-9, thereby reducing the value of MMP-9 as a biomarker. The aim of this study was to evaluate the impact of AT on circulating MMP-9, and if the metabolic syndrome might have a modifying effect. Methods: Gene expression of MMP-9 was measured in AT, isolated adipocytes, atherosclerotic plaques, macrophages and various other human tissues using real-time PCR. Relationships between plasma MMP-9 (ELISA), adiposity, and metabolic syndrome were analyzed in a population-based cohort of 61-year-old men (n=513). Both AT mRNA levels and circulating levels of MMP-9 were measured in obese subjects (n=40) with and without the metabolic syndrome, treated with a weight-reducing diet. Results: Bone marrow, atherosclerotic plaques and macrophages had considerably higher MMP-9 mRNA than subcutaneous AT and isolated adipocytes. Among the 61-year-old men, active plasma MMP-9 concentrations were associated with several metabolic syndrome factors, and inflammatory markers, but not body mass index (BMI). In obese patients with, but not without metabolic syndrome AT mRNA levels and circulating MMP-9 declined during weight reduction, but there was no association between changes in plasma MMP-9 and BMI. Conclusion: The results show that adipose tissue per se is not associated with circulating MMP-9. Components of the metabolic syndrome, such as circulating insulin and glucose were related to plasma MMP-9 both in the observation and dietary weight loss studies.