The −1562C/T MMP-9 promoter polymorphism does not predict MMP-9 expression levels or invasive capacity in saphenous vein smooth muscle cells cultured from different patients

The MMP-9 promoter genetic variant rs3918242, mRNA and protein expression in advanced carotid plaque tissue

BACKGROUND

The MMP-9 is a known player in atherosclerosis, yet associations of the MMP-9 -1562 C/T variant (rs3918242) with various atherosclerotic phenotypes and tissue mRNA expression are still contradictory. This study aimed to investigate the MMP-9 -1562 C/T variant, its mRNA and protein expression in carotid plaque (CP) tissue, as a risk factor for CP presence and as a marker of different plaque phenotypes (hyperechoic and hypoechoic) in patients undergoing carotid endarterectomy. The MnSOD as an MMP-9 negative regulator was also studied in relation to CP phenotypes.

METHODS AND RESULTS

Genotyping of 770 participants (285 controls/485 patients) was done by tetra-primer ARMS PCR. The MMP-9 mRNA expression in 88 human CP tissues was detected by TaqMan® technology. The protein levels of MMP-9 and MnSOD were assessed by Western blot analysis. The MMP-9 -1562 C/T variant was not recognized as a risk factor for plaque presence or in predisposing MMP-9 mRNA and protein levels in plaque tissue. Patients with hypoechoic plaques had significantly lower MMP-9 mRNA and protein levels than those with hyperechoic plaque (p = 0.008, p = 0.003, respectively). MnSOD protein level was significantly higher in hypoechoic plaque compared to hyperechoic (p = 0.039). MMP-9 protein expression in CP tissue was significantly affected by sex and plaque type interaction (p = 0.009).

CONCLUSIONS

Considering the differences of MMP-9 mRNA and protein expression in CP tissue regarding different plaque phenotypes and the observed sex-specific effect, the role of MMP-9 in human atherosclerotic plaques should be further elucidated.

Exploring smooth muscle phenotype and function in a bioreactor model of abdominal aortic aneurysm

Background

Vascular smooth muscle cells (SMC) are central to arterial structure and function yet their involvement in the progression of abdominal aortic aneurysm (AAA) disease is not well studied. The progressive and silent nature of AAA in man essentially restricts research to the use of “end-stage” tissue recovered during surgical repair. This study aimed to generate an ex vivo model of AAA using protease-treated porcine carotid arteries maintained in a novel bioreactor, and to compare the structural and functional changes in SMC cultured from the recovered vessels with those from human tissue acquired at elective surgical repair.

Methods

Freshly isolated porcine arteries were pretreated with collagenase and/or elastase before culturing under flow in a bioreactor for 12 days. Human end-stage aneurysmal tissue and saphenous veins from age-matched controls were collected from patients undergoing surgery. SMC were cultured and characterised (immunocytochemistry, measurement of spread cell area) and assessed functionally at the level of proliferation (cell-counting) and matrix-metalloproteinase (MMP) secretion (gelatin zymography). Cellular senescence was investigated using β-galactosidase staining and apoptosis was quantified using a fluorescence-based caspase 3 assay.

Results

Co-expression of alpha-smooth muscle actin and smooth muscle myosin heavy chain confirmed all cell populations as SMC. Porcine SMC harvested and cultivated after collagenase/elastase pretreatment displayed a prominent “rhomboid” morphology, increased spread area (32%, P < 0.01), impaired proliferation (47% reduction, P < 0.05), increased senescence (52%, P < 0.001), susceptibility to apoptosis and reduced MMP-2 secretion (60% decrease, P < 0.01) compared with SMC from vehicle, collagenase or elastase pre-treated vessels. Notably, these changes were comparable to those observed in human AAA SMC which were 2.4-fold larger than non-aneurysmal SMC (P < 0.001) and exhibited reduced proliferation (39% reduction, P < 0.001), greater apoptosis (4-fold increase, P < 0.001), and increased senescence (61%, P < 0.05).

Conclusions

Combined collagenase/elastase exposure of porcine artery maintained in a bioreactor under flow conditions induced a SMC phenotype characteristic of those cultured from end-stage AAA specimens. This model has potential and versatility to examine temporal changes in SMC biology and to identify the molecular mechanisms leading to early aberrancies in SMC function. In the longer term this may inform new targets to maintain aortic SMC content and drive cells to a “reparative” phenotype at early stages of the disease.

Expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in recurrent chronic rhinosinusitis with nasal polyposis

Matrix metalloproteinase (MMP) is involved in the upper airway remodeling process. We hypothesized that MMP had an additive effect on the formation of recurrent nasal polyp. We also investigated the association between the functional promoter polymorphism of MMPs and the intensity of labeling index. Expressions of MMP-2 and MMP-9 were assessed via immunohistochemical staining and compared between different groups, including recurrent nasal polyps, nonrecurrent nasal polyps, and control nasal mucosa. Two promoter functional single-nucleotide polymorphisms (rs3918242 for MMP-9 and rs243865 for MMP-2) were selected to correlate with staining intensity. Expression of MMP-9 was significantly enhanced in gland for recurrent nasal polyp (p = 0.016) and nonrecurrent nasal polyp (p = 0.005) compared to the control. MMP-2 positivity was significantly increased in surface epithelium for recurrent nasal polyp (p = 0.004) compared to the control (p = 0.061). However, there was no significant difference in MMP-9 and MMP-2 expressions between recurrent and nonrecurrent nasal polyps. Genetic polymorphism of MMP-2 and MMP-9 functional promoters was not associated with the intensity of labeling index. These results suggested that up-regulation of MMP-9 in gland and MMP-2 in surface epithelium was characteristic of both recurrent and nonrecurrent nasal polyps. Pathogenesis of recurrent nasal polyps may involve a mechanism other than MMP.

Matrix metalloproteinase-9 genotype as a potential genetic marker for abdominal aortic aneurysm

BACKGROUND

Degradation of extracellular matrix support in the large abdominal arteries contribute to abnormal dilation of aorta, leading to abdominal aortic aneurysms, and matrix metalloproteinase-9 (MMP-9) is the predominant enzyme targeting elastin and collagen present in the walls of the abdominal aorta. Previous studies have suggested a potential association between MMP-9 genotype and abdominal aortic aneurysm, but these studies have been limited only to the p-1562 and (CA) dinucleotide repeat microsatellite polymorphisms in the promoter region of the MMP-9 gene. We determined the functional alterations caused by 15 MMP-9 single-nucleotide polymorphisms (SNPs) reported to be relatively abundant in the human genome through Western blots, gelatinase, and promoter-reporter assays and incorporated this information to perform a logistic-regression analysis of MMP-9 SNPs in 336 human abdominal aortic aneurysm cases and controls.

METHODS AND RESULTS

Significant functional alterations were observed for 6 exon SNPs and 4 promoter SNPs. Genotype analysis of frequency-matched (age, sex, history of hypertension, hypercholesterolemia, and smoking) cases and controls revealed significant genetic heterogeneity exceeding 20% observed for 6 SNPs in our population of mostly white subjects from Northern Wisconsin. A step-wise logistic-regression analysis with 6 functional SNPs, where weakly contributing confounds were eliminated using Akaike information criteria, gave a final 2 SNP (D165N and p-2502) model with an overall odds ratio of 2.45 (95% confidence interval, 1.06-5.70).

CONCLUSIONS

The combined approach of direct experimental confirmation of the functional alterations of MMP-9 SNPs and logistic-regression analysis revealed significant association between MMP-9 genotype and abdominal aortic aneurysm.

Genetic variation, gene-expression and circulating levels of matrix metalloproteinase-9 in patients with stable coronary artery disease

BACKGROUND

Mediators involved in atherosclerosis and plaque rupture may have importance as risk markers for coronary artery disease (CAD). We have investigated the influence of matrix metalloproteinase (MMP)-9 genetic variations on gene- and protein expression in stable CAD patients.

METHODS

The promoter -1562C/T and exon 6 R279Q A/G polymorphisms were determined in 1001 patients with angiographically verified stable CAD and in 204 healthy controls. Genotype and gene-expression were determined by real-time PCR. Serum levels of MMP-9 and its inhibitor TIMP-1were measured immunologically and by zymography (MMP-9 activity).

RESULTS

None of the polymorphisms associated with the presence of CAD, myocardial infarction or type 2 diabetes, whereas the variant allele of the R279Q polymorphism associated with hypertension (adjusted p=0.015). The T- and G alleles associated with lower and higher mRNA levels, respectively (p<0.005 both), also shown in an experimental ex-vivo LPS stimulated model. T-allele carriers had higher concentrations of MMP-9 (adjusted p=0.032) and the GG genotype induced lower MMP-9 gelatinolytic activity (p=0.01). Higher MMP-9 gene-expression and TIMP-1 levels were observed in patients with previous myocardial infarction, the latter also was elevated in diabetics (<0.05, all).

CONCLUSION

The investigated MMP-9 polymorphisms influenced gene- and protein expression differently and the R279Q polymorphism associated significantly with hypertension.

MMP-3 (5A/6A) polymorphism does not influence human smooth muscle cell invasion

BACKGROUND

Stromelysin (MMP-3) is an important regulator of vascular smooth muscle cell (SMC) invasion, a key contributor to saphenous vein (SV) bypass graft failure. The 5A allele of the common -1612 MMP-3 5A/6A promoter polymorphism reportedly confers increased promoter activity, MMP-3 tissue expression, and susceptibility to a number of vascular pathologies. The aim of this study was to determine whether the MMP-3 5A/6A polymorphism directly influences endogenous MMP-3 expression levels and, consequently, cell invasion, in SV-derived SMC cultured from patients with different genotypes.

MATERIAL AND METHODS

Genotyping of 226 patients revealed -1612 MMP-3 5A/6A genotype frequencies of 20.8% 5A/5A, 52.7% 5A/6A, and 26.5% 6A/6A. Using a standardized, controlled protocol, we investigated cytokine- and growth factor-induced MMP-3 expression (real-time polymerase chain reaction [RT-PCR], ELISA) and SV-SMC invasion (Boyden chamber with Matrigel barrier) using cultured SV-SMC from patients with different MMP-3 genotypes.

RESULTS

Despite observing a strong correlation between MMP-3 mRNA levels and MMP-3 protein secretion, no significant differences were apparent in MMP-3 expression levels or cell invasion between cells with different MMP-3 5A/6A genotypes.

CONCLUSIONS

Our data suggest that the MMP-3 5A/6A promoter polymorphism in isolation does not influence levels of MMP-3 secretion or cellular invasion in human SV-SMC.

Matrix metalloproteinase-9 gene polymorphisms in nasal polyposis

Background

Matrix metalloproteinase (MMP) is involved in the upper airway remodeling process. We hypothesized that genetic variants of the MMP-9 gene are associated with cases of chronic rhinosinusitis with nasal polyposis.

Methods

We conducted a case-control study where 203 cases of chronic rhinosinusitis with nasal polyposis and 730 controls were enrolled. Three tagging single nucleotide polymorphisms (SNPs) and one promoter functional SNP rs3918242 were selected. Hardy-Weinberg equilibrium (HWE) was tested for each SNP, and genetic effects were evaluated according to three inheritance modes. Haplotype analysis was also performed. Permutation was used to adjust for multiple testing.

Results

All four SNPs were in HWE. The T allele of promoter SNP rs3918242 was associated with chronic rhinosinusitis with nasal polyposis under the dominant (nominal p = 0.023, empirical p = 0.022, OR = 1.62) and additive models (nominal p= 0.012, empirical p = 0.011, OR = 1.60). The A allele of rs2274756 has a nominal p value of 0.034 under the dominant model and 0.020 under the additive model. Haplotype analysis including the four SNPs showed a global p value of 0.015 and the most significant haplotype had a p value of 0.0045. We did not see any SNP that was more significant in the recurrent cases.

Conclusions

We concluded that MMP-9 gene polymorphisms may influence susceptibility to the development of chronic rhinosinusitis with nasal polyposis in Chinese population.