Genetic analysis of polymorphisms in biologically relevant candidate genes in patients with abdominal aortic aneurysms

Hereditary Aortic Aneurysms and Dissections: Clinical Diagnosis and Genetic Testing

Hereditary aortic aneurysms and dissections, such as Marfan syndrome, differ in that they occur in younger patients without generally recognized risk factors, have a predilection for the thoracic rather than the abdominal aorta, and are at risk for dissection even at smaller aortic diameters. Early diagnosis, careful follow-up, and early intervention, such as medication to reduce aortic root growth and prophylactic aortic replacement to prevent fatal aortic dissection, are essential for a better prognosis. Molecular genetic testing is extremely useful for early diagnosis. However, in actual clinical practice, the question often arises as to when and to which patient genetic testing should be offered since the outcome of the tests can have important implications for the patient and the relatives. Pre- and post-test genetic counseling is essential for early intervention to be effective. (This article is a secondary translation of Jpn J Vasc Surg 2023; 32: 261-267.).

Comparison of Genes Associated with Thoracic and Abdominal Aortic Aneurysms

Aneurysms impacting the ascending thoracic aorta and the abdominal aorta affect patient populations with distinct clinical characteristics. Through a literature review, this paper compares the genetic associations of ascending thoracic aortic aneurysm (ATAA) with abdominal aortic aneurysms (AAA). Genes related to atherosclerosis, lipid metabolism, and tumor development are associated specifically with sporadic AAA, while genes controlling extracellular matrix (ECM) structure, ECM remodeling, and tumor growth factor β function are associated with both AAA and ATAA. Contractile element genes uniquely predispose to ATAA. Aside from known syndromic connective tissue disease and poly-aneurysmal syndromes (Marfan disease, Loeys-Dietz syndrome, and Ehlers-Danlos syndrome), there is only limited genetic overlap between AAA and ATAA. The rapid advances in genotyping and bioinformatics will elucidate further the various pathways associated with the development of aneurysms affecting various parts of the aorta.

The CCN2 Polymorphism rs12526196 Is a Risk Factor for Ascending Thoracic Aortic Aneurysm

Cellular communication network factor 2 (CCN2/CTGF) has been traditionally described as a downstream mediator of other profibrotic factors including transforming growth factor (TGF)-β and angiotensin II. However, recent evidence from our group demonstrated the direct role of CCN2 in maintaining aortic wall homeostasis and acute and lethal aortic aneurysm development induced by angiotensin II in the absence of CCN2 in mice. In order to translate these findings to humans, we evaluated the potential association between three polymorphisms in the CCN2 gene and the presence of a thoracic aortic aneurysm (TAA). Patients with and without TAA retrospectively selected were genotyped for rs6918698, rs9402373 and rs12526196 polymorphisms related to the CCN2 gene. Multivariable logistic regression models were performed. In our population of 366 patients (69 with TAA), no associations were found between rs6918698 and rs9402373 and TAA. However, the presence of one C allele from rs12526196 was associated with TAA comparing with the TT genotype, independently of risk factors such as sex, age, hypertension, type of valvulopathy and the presence of a bicuspid aortic valve (OR = 3.17; 95% CI = 1.30-7.88; p = 0.011). In conclusion, we demonstrated an association between the C allele of rs12526196 in the CCN2 gene and the presence of TAA. This study extrapolates to humans the relevance of CCN2 in aortic aneurysm observed in mice and postulates, for the first time, a potential protective role to CCN2 in aortic aneurysm pathology. Our results encourage future research to explore new variants in the CCN2 gene that could be predisposed to TAA development.

The evolutionary background and functional consequences of the rs2071307 polymorphism in human tropoelastin

Elastin is a major polymeric protein of the extracellular matrix, providing critical properties of extensibility and elastic recoil. The rs2071307 genomic polymorphism, resulting in the substitution of a serine for a glycine residue in a VPG motif in tropoelastin, has an unusually high minor allele frequency in humans. A consequence of such allelic heterozygosity would be the presence of a heterogeneous elastin polymer in up to 50% of the population, a situation which appears to be unique to Homo sapiens. VPG motifs are extremely common in hydrophobic domains of tropoelastins and are the sites of transient β-turns that are essential for maintaining the conformational flexibility required for its function as an entropic elastomer. Earlier data demonstrated that single amino acid substitutions in tropoelastin can have functional consequences for polymeric elastin, particularly when present in mixed polymers. Here, using NMR and molecular dynamics approaches, we show the rs2071307 polymorphism reduces local propensity for β-turn formation, with a consequent increase in polypeptide hydration and an expansion of the conformational ensemble manifested as an increased hydrodynamic radius, radius of gyration and asphericity. Furthermore, this substitution affects functional properties of polymeric elastin, particularly in heterogeneous polymers mimicking allelic heterozygosity. We discuss whether such effects, together with the unusually high minor allele frequency of the polymorphism, could imply some some evolutionary advantage for the heterozygous state.

Disturbed nitric oxide signalling gives rise to congenital bicuspid aortic valve and aortopathy

Patients with a congenital bicuspid aortic valve (BAV), a valve with two instead of three aortic leaflets, have an increased risk of developing thoracic aneurysms and aortic dissection. The mechanisms underlying BAV-associated aortopathy are poorly understood. This study examined BAV-associated aortopathy in Nos3^−/− mice, a model with congenital BAV formation. A combination of histological examination and in vivo ultrasound imaging was used to investigate aortic dilation and dissections in Nos3^−/− mice. Moreover, cell lineage analysis and single-cell RNA sequencing were used to observe the molecular anomalies within vascular smooth muscle cells (VSMCs) of Nos3^−/− mice. Spontaneous aortic dissections were found in ascending aortas located at the sinotubular junction in ∼13% of Nos3^−/− mice. Moreover, Nos3^−/− mice were prone to developing aortic dilations in the proximal and distal ascending aorta during early adulthood. Lower volumes of elastic fibres were found within vessel walls of the ascending aortas of Nos3^−/− mice, as well as incomplete coverage of the aortic inner media by neural crest cell (NCC)-derived VSMCs. VSMCs of Nos3^−/− mice showed downregulation of 15 genes, of which seven were associated with aortic aneurysms and dissections in the human population. Elastin mRNA was most markedly downregulated, followed by fibulin-5 expression, both primary components of elastic fibres. This study demonstrates that, in addition to congenital BAV formation, disrupted endothelial-mediated nitric oxide (NO) signalling in Nos3^−/− mice also causes aortic dilation and dissection, as a consequence of inhibited elastic fibre formation in VSMCs within the ascending aorta.

Summary: Nitric oxide defects link bicuspid aortic valve formation and aortopathy through inhibition of elastic fibre formation in vascular smooth muscle cells within the ascending aorta of Nos3^−/− mice.

Type III collagen (COL3A1): Gene and protein structure, tissue distribution, and associated diseases

Collagen alpha-1(III) chain, also known as the alpha 1 chain of type III collagen, is a protein that in humans is encoded by the COL3A1 gene. Three alpha 1 chains are required to form the type III collagen molecule which has a long triple-helical domain. Type III collagen, an extracellular matrix protein, is synthesized by cells as a pre-procollagen. It is found as a major structural component in hollow organs such as large blood vessels, uterus and bowel. Other functions of type III collagen include interaction with platelets in the blood clotting cascade and it is also an important signaling molecule in wound healing. Mutations in the COL3A1 gene cause the vascular type of Ehlers-Danlos syndrome (vEDS; OMIM 130050). It is the most serious form of EDS, since patients often die suddenly due to a rupture of large arteries. Inactivation of the murine Col3a1 gene leads to a shorter life span in homozygous mutant mice. The mice die prematurely from a rupture of major arteries mimicking the human vEDS phenotype. The biochemical and cellular effects of COL3A1 mutations have been studied extensively. Most of the glycine mutations lead to the synthesis of type III collagen with reduced thermal stability, which is more susceptible for proteinases. Intracellular accumulation of this normally secreted protein is also found. Ultrastructural analyses have demonstrated dilated rough endoplasmic reticulum and changes in the diameter of collagen fibers. Other clinical conditions associated with type III collagen are several types of fibroses in which increased amounts of type III collagen accumulate in the target organs.

Relationship of genetic factors with development of aortic dissection and aneurysm

Background

This study aims to investigate the relationship between the development of aortic dissections and aneurysms with the polymorphisms of angiotensin converting enzyme gene, methylenetetrahydrofolate reductase gene, plasminogen activator inhibitor-1 gene, and nitric oxide synthase gene.

Methods

Between April 2009 and July 2014, 38 patients with aortic dissections (28 males, 10 females; mean age 55.1±10.7 years; range, 30 to 78 years) and 67 patients with aortic aneurysms (57 males, 10 females; mean age 63.0±11.4 years; range, 31 to 82 years) were included in this cross-sectional study. The control group consisted of 60 healthy volunteers (41 males, 19 females; mean age 56.3±11.2 years; range, 30 to 82 years) without an aortic aneurysm or dissection, as assessed by thoracoabdominal computed tomography. The prespecified four genes were genotyped with competitive allelespecific polymerase chain reaction.

Results

The aortic dissection group had higher nitric oxide synthase-3 (4b/4b) expression levels, compared to the control group. The aortic aneurysm group had also higher nitric oxide synthase-3 (4b/4a) expression levels, compared to the control group. Compared to the control group, a higher rate of angiotensin converting enzyme I/D gene polymorphism was detected in the aneurysm group, while higher D/D polymorphism rates were found in the dissection group; although not statistically significant.

Conclusion

Our study results suggest that the nitric oxide synthase-3 intron 4b/4b and nitric oxide synthase-3 intron 4b/4a gene polymorphisms can be used as a predictor of aortic dissection and aneurysm development.

Abdominal Aortic Aneurysm: Evolving Controversies and Uncertainties

Abdominal aortic aneurysm (AAA) is defined as a permanent dilatation of the abdominal aorta that exceeds 3 cm. Most AAAs arise in the portion of abdominal aorta distal to the renal arteries and are defined as infrarenal. Most AAAs are totally asymptomatic until catastrophic rupture. The strongest predictor of AAA rupture is the diameter. Surgery is indicated to prevent rupture when the risk of rupture exceeds the risk of surgery. In this review, we aim to analyze this disease comprehensively, starting from an epidemiological perspective, exploring etiology and pathophysiology, and concluding with surgical controversies. We will pursue these goals by addressing eight specific questions regarding AAA: (1) Is the incidence of AAA increasing? (2) Are ultrasound screening programs for AAA effective? (3) What causes AAA: Genes versus environment? (4) Animal models: Are they really relevant? (5) What pathophysiology leads to AAA? (6) Indications for AAA surgery: Are surgeons over-eager to operate? (7) Elective AAA repair: Open or endovascular? (8) Emergency AAA repair: Open or endovascular?

Risk Factor Assessment in a Greek Cohort of Patients With Large Abdominal Aortic Aneurysms

Environmental and genetic risk factors contribute to the etiology of abdominal aortic aneurysms (AAAs). Matrix metalloproteinases (MMPs) have been associated with the pathophysiology of AAAs. A prospective, nonrandomized case-control study was undertaken to investigate the risk factors for large AAAs (≥5.5 cm) among 175 male Greek AAA patients and to compare the results with a cohort of 166 male controls free from any aortic dilatation, as confirmed by ultrasonography from an existing AAA screening program in the same region. We also assessed the potential association between 2 functional single nucleotide polymorphisms in the genes MMP9 (-1561C/T; rs3918242) and MMP13 (-77A/G; rs2252070), and the presence of large AAAs. Multiple logistic regression analysis revealed AAA family history ( P = .028), hypercholesterolemia ( P < .001), and current smoking ( P < .001) as AAA risk factors. Statistical difference was reached in genotype ( P = .047) and allele ( P = .037) frequencies for rs2252070, but the results did not remain significant after correction for multiple testing. No significant differences in genotype or allele frequencies for rs3918242 were detected. In summary, AAA family history, hypercholesterolemia, and current smoking were found to be risk factors for large AAAs.

Multiple sites of vascular dilation or aneurysmal disease and matrix metalloproteinase genetic variants in patients with abdominal aortic aneurysm

OBJECTIVE

The objective of this study was to assess whether functional genetic polymorphisms of matrix metalloproteinases (MMPs) 1, 3, 9, and 12 are associated with arterial enlargements or aneurysms of the thoracic aorta or popliteal arteries in patients with abdominal aortic aneurysm (AAA).

METHODS

The associations between MMP1 (-1607 G in/del, rs1799750), MMP3 (-1171 A in/del rs35068180), MMP9 (13-26 CA repeats around -90, rs2234681, rs917576, rs917577), and MMP12 (G/T missense variation, rs652438) polymorphisms and enlargements or aneurysms of the thoracic aorta and popliteal arteries were tested in 169 consecutive AAA patients.

RESULTS

Thoracic aorta enlargement or aneurysm (TE/A; maximum diameter, >35 mm) was detected in 34 patients (20.1% prevalence). MMP9 rs2234681 microsatellite was the only genetic determinant of TE/A in AAA patients (P = .003), followed by hypercholesterolemia and antiplatelet use. Carriers of both alleles with ≥22 CA repeats had a 5.9 (95% confidence interval, 1.9-18.6; P < .0001) increased odds of TE/A, and a score considering all three variables showed 98% negative predictive value and 30% positive predictive value for thoracic aortic aneurysm detection. Eighty-two popliteal artery enlargements or aneurysms (diameter >10 mm) occurred in 55 patients (33.1% prevalence). Carriers of MMP12 rs652438 C allele showed an 18% (P = .006) increased diameter in popliteal arteries and a 2.8 (95% confidence interval, 1.3-6; P = .008) increased odds of popliteal artery enlargement or aneurysm compared with TT genotype.

CONCLUSIONS

Among patients with AAA, carriers of homozygous ≥22 CA repeats in MMP9 rs12234681 and of C allele in MMP12 rs652438 have a substantial risk of carrying thoracic and popliteal enlargements, respectively.

Matrix metalloproteinase family polymorphisms and the risk of aortic aneurysmal diseases: A systematic review and meta-analysis

It has been suggested that matrix metalloproteinase (MMP) polymorphisms are associated with the pathogenesis of aortic aneurysmal diseases. In this study, we conducted a systematic review with an update meta-analysis to investigate the relationship between MMP family polymorphisms and aortic aneurysmal diseases. We systematically reviewed 24 polymorphisms in 8 MMP genes related to the risk of abdominal aortic aneurysm (AAA), thoracic AA or thoracic aortic dissection (TAD). A total of 19 case-control studies with 15 highly studied MMP polymorphisms were included in our meta-analysis. Our results suggested that MMP2rs243865, MMP3rs3025058, MMP13rs2252070 polymorphisms were significantly associated with AAA risk, MMP2rs11643630, MMP8rs11225395 polymorphisms were correlated with TAD risk, and MMP9rs3918242 under the dominant model could increase AAA risk in hospital-based subgroup. No associations with aortic aneurysmal diseases were identified for other polymorphisms assessed in our meta-analysis. In summary, some studied MMP polymorphisms associated with the risk of aortic aneurysmal diseases are potential predictive biomarkers for the clinical application. Moreover, other MMP polymorphisms with limited studies but relevant to aortic aneurysmal formation and progression need further prospective and large investigations to confirm results.

The Role Matrix Metalloproteinases in the Production of Aortic Aneurysm

Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of aortic aneurysm because the histology of thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) is characterized by the loss of smooth muscle cells in the aortic media and the destruction of extracellular matrix (ECM). Furthermore, AAA have evidence of inflammation and the cellular elements involved in inflammation such as macrophages can produce and/or activate MMPs This chapter focuses on human aortic aneurysm that are not due to specific known genetic causes because this type of aneurysm is the more common type. This chapter will also focus on MMP protein expression rather than on genetic data which may not necessarily translate to increased MMP protein expression. There are supporting data that certain MMPs are increased in the aortic wall. For TAA, it is most notably MMP-1, -9, -12, and -14 and MMP-2 when a bicuspid aortic valve is present. For AAA, it is MMP-1, -2, -3, -9, -12, and -13. The data are weaker or insufficient for the other MMPs. Several studies of gene polymorphisms support MMP-9 for TAA and MMP-3 for AAA as potentially important factors. The signaling pathways in the aorta that can lead to MMP activation include JNK, JAK/stat, osteopontin, and AMP-activated protein kinase alpha2. Substrates in the human vasculature for MMP-3, MMP-9, or MMP-14 include collagen, elastin, ECM glycoprotein, and proteoglycans. Confirmed and potential substrates for MMPs, maintain aortic size and function so that a reduction in their content relative to other components of the aortic wall may produce a failure to maintain aortic size leading to dilatation and aneurysm formation.

Genetic and Epigenetic Regulation of Aortic Aneurysms

Aneurysms are characterized by structural deterioration of the vascular wall leading to progressive dilatation and, potentially, rupture of the aorta. While aortic aneurysms often remain clinically silent, the morbidity and mortality associated with aneurysm expansion and rupture are considerable. Over 13,000 deaths annually in the United States are attributable to aortic aneurysm rupture with less than 1 in 3 persons with aortic aneurysm rupture surviving to surgical intervention. Environmental and epidemiologic risk factors including smoking, male gender, hypertension, older age, dyslipidemia, atherosclerosis, and family history are highly associated with abdominal aortic aneurysms, while heritable genetic mutations are commonly associated with aneurysms of the thoracic aorta. Similar to other forms of cardiovascular disease, family history, genetic variation, and heritable mutations modify the risk of aortic aneurysm formation and provide mechanistic insight into the pathogenesis of human aortic aneurysms. This review will examine the relationship between heritable genetic and epigenetic influences on thoracic and abdominal aortic aneurysm formation and rupture.

MicroRNA-181b Controls Atherosclerosis and Aneurysms Through Regulation of TIMP-3 and Elastin

Supplemental Digital Content is available in the text.

Rationale:

Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood.

Objective:

To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms.

Methods and Results:

Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe^−/− and Ldlr^−/−, we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II–infused Apoe^−/− and Ldlr^−/− mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3^−/− mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis.

Conclusions:

Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.

Abdominal Aortic Aneurysm Genetic Associations: Mostly False? A Systematic Review and Meta-analysis

OBJECTIVE/BACKGROUND

Many associations between abdominal aortic aneurysm (AAA) and genetic polymorphisms have been reported. It is unclear which are genuine and which may be caused by type 1 errors, biases, and flexible study design. The objectives of the study were to identify associations supported by current evidence and to investigate the effect of study design on reporting associations.

METHODS

Data sources were MEDLINE, Embase, and Web of Science. Reports were dual-reviewed for relevance and inclusion against predefined criteria (studies of genetic polymorphisms and AAA risk). Study characteristics and data were extracted using an agreed tool and reports assessed for quality. Heterogeneity was assessed using I(2) and fixed- and random-effects meta-analyses were conducted for variants that were reported at least twice, if any had reported an association. Strength of evidence was assessed using a standard guideline.

RESULTS

Searches identified 467 unique articles, of which 97 were included. Of 97 studies, 63 reported at least one association. Of 92 studies that conducted multiple tests, only 27% corrected their analyses. In total, 263 genes were investigated, and associations were reported in polymorphisms in 87 genes. Associations in CDKN2BAS, SORT1, LRP1, IL6R, MMP3, AGTR1, ACE, and APOA1 were supported by meta-analyses.

CONCLUSION

Uncorrected multiple testing and flexible study design (particularly testing many inheritance models and subgroups, and failure to check for Hardy-Weinberg equilibrium) contributed to apparently false associations being reported. Heterogeneity, possibly due to the case mix, geographical, temporal, and environmental variation between different studies, was evident. Polymorphisms in nine genes had strong or moderate support on the basis of the literature at this time. Suggestions are made for improving AAA genetics study design and conduct.

TIMP-3 -1296 T>C and TIMP-4 -55 T>C gene polymorphisms play a role in the susceptibility of hepatocellular carcinoma among women

The purpose of this study was to investigate genetic impact of TIMP-3 -1296 T>C (rs9619311) and TIMP-4 -55 T>C (rs3755724) gene polymorphisms on the susceptibility and clinicopathological characteristics of hepatocellular carcinoma (HCC). A total of 759 subjects, including 530 healthy controls and 229 patients with hepatocellular carcinoma, were recruited in this study. Allelic discrimination of TIMP-3 -1296 T>C (rs9619311) and TIMP-4 -55 T>C (rs3755724) polymorphisms was assessed with the ABI StepOne™ Real-Time PCR System. Among women group, individuals with TC or CC alleles of TIMP-3 -1296 T>C gene polymorphism protected against HCC (AOR = 0.35, 95% confidence interval (CI) = 0.12-0.97; p = 0.04) compared to individuals with TT alleles, after adjusting for other confounders. Also, women with TC alleles and with TC or CC alleles of TIMP-4 -55 T>C polymorphisms had a 2.52-fold risk (95%CI = 1.23-5.13; p = 0.01) and 2.47-fold risk (95%CI = 1.26-4.87; p = 0.008) of developing HCC compared to individuals with TT alleles, after adjusting for other confounders. There was no synergistic effect between gene polymorphism and environmental risk factors, including tobacco and alcohol consumptions and clinical statuses of HCC as well as serum expression of liver-related clinicopathological markers. In conclusion, gene polymorphisms of TIMP-3 -1296 T>C (rs9619311) and TIMP-4 -55 T>C (rs3755724) play a role in the susceptibility of HCC among Taiwan women.

Tissue inhibitor of matrix metalloproteinase-1 polymorphism, plasma TIMP-1 levels, and antihypertensive therapy responsiveness in hypertensive disorders of pregnancy

Tissue inhibitor of metalloproteinase (TIMP)-1 is a major endogenous inhibitor of matrix metalloproteinase (MMP)-9, which may affect the responsiveness to therapy in hypertensive disorders of pregnancy. We examined whether TIMP-1 polymorphism (g.-9830T>G, rs2070584) modifies plasma MMP-9 and TIMP-1 levels and the response to antihypertensive therapy in 596 pregnant: 206 patients with preeclampsia (PE), 183 patients with gestational hypertension (GH) and 207 healthy pregnant controls. We also studied the TIMP-3 polymorphism (g.-1296T>C, rs9619311). Plasma MMP-9 and TIMP-1 levels were measured by ELISA. GH patients with the GG genotype for the TIMP-1 polymorphism had lower MMP-9 levels and MMP-9/TIMP-1 ratios than those with the TT genotype. PE patients with the TG genotype had higher TIMP-1 levels. The G allele and the GG genotype were associated with PE and responsiveness to antihypertensive therapy in PE, but not in GH. Our results suggest that the TIMP-1 g.-9830T>G polymorphism not only promotes PE but also decreases the responses to antihypertensive therapy.

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

Smooth muscle cells from abdominal aortic aneurysms are unique and can independently and synergistically degrade insoluble elastin

BACKGROUND

The purpose of this study was to further elucidate the role of the vascular smooth muscle cells (SMCs) in abdominal aortic aneurysm (AAA) disease. We hypothesized that that AAA SMCs are unique and actively participate in the process of degrading the aortic matrix.

METHODS

Whole-genome expression profiles of SMCs from AAAs, nondilated abdominal aorta (NAA), and carotid endarterectomy (CEA) were compared. We quantified elastolytic activity by culturing SMCs in [(3)H]elastin-coated plates and measuring solubilized tritium in the media after 7 days. Matrix metalloproteinase (MMP)-2 and MMP-9 production was assessed using real-time polymerase chain reaction, zymography, and Western blotting.

RESULTS

Each SMC type exhibited a unique gene expression pattern. AAA SMCs had greater elastolytic activity than NAA-SMCs (+68%; P < .001) and CEA-SMCs (+45%; P < .001). Zymography showed an increase of active MMP-2 (62 kD) in media from AAA SMCs. AAA SMCs demonstrated twofold greater expression of MMP-2 messenger (m)RNA (P < .05) and 7.3-fold greater MMP-9 expression (P < .01) than NAA-SMCs. Culture with U937 monocytes caused a synergistic increase of elastolysis by AAA SMCs (41%; P < .001) but not NAA-SMCs or CEA-SMCs (P = .99). Coculture with U937 caused a large increase in MMP-9 mRNA in AAA-SMCs and NAA-SMCs (P < .001). MMP-2 mRNA expression was not affected. Western blots of culture media showed a fourfold increase of MMP-9 (92 kD) protein only in AAA-SMCs/U937 but not in NAA-SMCs/U937 (P < .001) and a large increase in active-MMP2 (62 kD), which was less apparent in NAA-SMCs/U937 media (P < .01).

CONCLUSIONS

AAA-SMCs have a unique gene expression profile and a proelastolytic phenotype that is augmented by macrophages. This may occur by a failure of post-transcriptional control of MMP-9 synthesis.

TIMP-1 polymorphisms in a Chinese Han population with intracerebral hemorrhage

Remodeling of extracellular matrix (ECM) and breakdown of blood-brain barrier (BBB) are crucial events in the pathogenesis of intracerebral hemorrhage (ICH). Matrix metalloproteinases (MMPs), particularly MMP-9 and MMP-2, are the most important degrading enzymes in the ECM and BBB. These proteolytic effects are controlled predominantly by tissue inhibitors of metalloproteinases (TIMPs). TIMP-1 is the main endogenous inhibitor of MMP-9. Two polymorphisms in the TIMP-1 gene (rs4898 and rs2070584) were selected through a literature review and successfully genotyped in a study sample of 410 ICH patients and 305 controls. Differences in genotype and allele frequencies of identified polymorphisms were determined. Furthermore, the serum levels of TIMP-1 were measured in a subgroup of 96 ICH patients on days 1 after ICH onset and 76 controls. Analyses showed that C allele of rs2070584 was significantly associated with the development of ICH in male subjects (p = 0.037, OR = 1.535, 95%CI 1.025-2.300). Multiple logistic regression analysis under three genetic models demonstrated both rs4898 and rs2070584 were not risk factors for ICH in female subjects. Furthermore, serum levels of TIMP-1 were significantly higher in ICH patients than those in normal controls. However, the serum levels of TIMP-1 showed a nonsignificant decrease, depending on the alleles and genotypes of rs2070584 both in male and female cases. In conclusion, this is the first association study of the TIMP-1 gene variants with ICH. Our data suggest that C allele of rs2070584 is a risk factor for ICH development in the Chinese male population. However, the precise function of this variant needs further investigation.

Genetic polymorphisms in matrix metalloproteinases (MMPs) and tissue inhibitors of MPs (TIMPs), and bladder cancer susceptibility

OBJECTIVES

To elucidate genetic polymorphisms of the matrix metalloproteinases (MMPs) MMP1 (rs1799750), MMP2 (rs243865), MMP9 (rs3918242), MMP12 (rs2276109) and tissue inhibitors of MMPs (TIMPs) TIMP1 (rs2070584) and TIMP3 (rs9619311) genes that may be involved in susceptibility to bladder cancer (BC).

PATIENTS AND METHODS

We enrolled 241 patients with BC and 199 controls. Genomic DNA samples were extracted from peripheral blood and polymorphisms were analysed by high-resolution melting analysis and by real-time polymerase chain reaction using TaqMan fluorescent probes.

RESULTS

Of the six evaluated polymorphisms of MMPs and TIMPs, only one was found to be associated with BC risk. There was a significant difference for MMP1 (rs1799750) 2G/1G+1G/1G genotype (odds ratio [OR] 0.62, 95% confidence interval [CI] 0.39-0.98; P = 0.042). Additionally, there was a joint effect of this genotype on BC risk among 'ever smokers' (OR 0.51, 95% CI 0.28-0.89; P = 0.019), but not in 'never smokers'. The combined genotype MMP2 -1306C/T (rs243865) allele T with MMP9 -1562C/T (rs3918242) allele T was found to increase BC risk (OR 2.00, 95% CI 1.10-3.62; P = 0.022).

CONCLUSIONS

Our results suggest that genetic variations in five polymorphisms of MMPs and TIMPs are not associated with a high risk of BC. Only MMP1 polymorphism may be related to the risk of BC, notably in 'ever smokers'. Our study suggests that the effects of polymorphisms of MMPs and TIMPs on BC risk deserve further investigation.

The 372 T/C genetic polymorphism of TIMP-1 is associated with serum levels of TIMP-1 and survival in patients with severe sepsis

INTRODUCTION

Previous studies have found higher circulating levels of tissue inhibitor of matrix metalloproteinase (TIMP)-1 in nonsurviving septic patients than in surviving septic patients, and an association between the 372 T/C genetic polymorphism of TIMP-1 and the risk of developing certain diseases. However, the relationship between genetic polymorphisms of TIMP-1, circulating TIMP-1 levels and survival in patients with severe sepsis has not been examined, and this was the objective of the study.

METHODS

This multicentre, prospective, observational study was carried out in six Spanish ICUs. We determined the 372 T/C genetic polymorphism of TIMP-1 (rs4898), serum levels of TIMP-1, matrix metalloproteinase (MMP)-9, MMP-10, TNFα, IL-10 and plasma plasminogen activator inhibitor-1 (PAI-1). Survival at 30 days from ICU admission was the endpoint assessed. The association between continuous variables was carried out using Spearman's rank correlation coefficient or Spearman's rho coefficient. Multivariate logistic regression analysis was applied to determine the association between the 372 T/C genetic polymorphism and survival 30 days from ICU admission.

RESULTS

Of 275 patients with severe sepsis, 80 had genotype CC, 55 had genotype CT and 140 had genotype TT of the 372 T/C genetic polymorphism of TIMP-1. Patients with the T allele showed higher serum levels of TIMP-1 than patients without the T allele (P=0.004). Multiple logistic regression analysis showed that the T allele was associated with higher mortality at 30 days (odds ratio=2.08; 95% confidence interval=1.06 to 4.09; P=0.03). Survival analysis showed that patients with the T allele presented lower 30-day survival than patients without the T allele (χ2=5.77; P=0.016). We found an association between TIMP-1 levels and levels of MMP-9 (ρ=-0.19; P=0.002), MMP-10 (ρ=0.55; P<0.001), TNFα (ρ=0.56; P<0.001), IL-10 (ρ=0.48; P<0.001) and PAI-1 (ρ=0.49; P<0.001).

CONCLUSION

The novel findings of our study are that septic patients with the T allele in the 372 T/C genetic polymorphism of TIMP-1 showed higher serum TIMP-1 levels and lower survival rate. The determination of the 372 T/C genetic polymorphism of TIMP-1 thus has prognostic implications and could help in the selection of patients who may benefit from modulation of the MMP/TIMP balance.

Assessment of the correlation between TIMP4 SNPs and schizophrenia and autism spectrum disorders

Tissue inhibitors of metalloproteinases (TIMPs) are involved in synaptic plasticity, neuronal cell differentiation and neuroprotection in the central nervous system. To investigate whether TIMP4 polymorphisms are associated with schizophrenia and autism spectrum disorders (ASDs), 480 patients (schizophrenia, n=287; ASDs, n=193) and 296 controls were enrolled. Clinical symptoms of schizophrenia and ASDs were assessed using the operation criteria checklist for psychotic illness (OPCRIT) and Childhood Autism Rating Scale (CARS), respectively. One promoter single nucleotide polymorphism (SNP; rs3755724, -55C/T) and one exonic SNP (rs17035945, 3'-untranslated region) were selected. SNPStats and SNPAnalyzer Pro programs were used to calculate odds ratios. Multiple logistic regression models were performed to analyze the genetic data. Based on the results, these two SNPs were not associated with schizophrenia and ASD. In the analysis of clinical features of schizophrenia, rs3755724 was nominally associated with schizophrenia with poor concentration (P=0.044 in the codominant2 model, P=0.041 in the log-additive model and P=0.043 in allele frequency). These results suggest that TIMP4 is not associated with the development of schizophrenia and ASD in the population studied.

Loss of Timp3 gene leads to abdominal aortic aneurysm formation in response to angiotensin II

Aortic aneurysm is dilation of the aorta primarily due to degradation of the aortic wall extracellular matrix (ECM). Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs), the proteases that degrade the ECM. Timp3 is the only ECM-bound Timp, and its levels are altered in the aorta from patients with abdominal aortic aneurysm (AAA). We investigated the causal role of Timp3 in AAA formation. Infusion of angiotensin II (Ang II) using micro-osmotic (Alzet) pumps in Timp3(-/-) male mice, but not in wild type control mice, led to adverse remodeling of the abdominal aorta, reduced collagen and elastin proteins but not mRNA, and elevated proteolytic activities, suggesting excess protein degradation within 2 weeks that led to formation of AAA by 4 weeks. Intriguingly, despite early up-regulation of MMP2 in Timp3(-/-)Ang II aortas, additional deletion of Mmp2 in these mice (Timp3(-/-)/Mmp2(-/-)) resulted in exacerbated AAA, compromised survival due to aortic rupture, and inflammation in the abdominal aorta. Reconstitution of WT bone marrow in Timp3(-/-)/Mmp2(-/-) mice reduced inflammation and prevented AAA in these animals following Ang II infusion. Treatment with a broad spectrum MMP inhibitor (PD166793) prevented the Ang II-induced AAA in Timp3(-/-) and Timp3(-/-)/Mmp2(-/-) mice. Our study demonstrates that the regulatory function of TIMP3 is critical in preventing adverse vascular remodeling and AAA. Hence, replenishing TIMP3, a physiological inhibitor of a number of metalloproteinases, could serve as a therapeutic approach in limiting AAA development or expansion.

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.

The C allele of synonymous SNP (rs1142636, Asn170Asn) in SYN1 is a risk factor for the susceptibility of Korean female schizophrenia

OBJECTIVE

The aim of this study was to investigate the association between the exonic single nucleotide polymorphisms (SNPs) of synapsin I (SYN1) (rs1142636, Asn170Asn, Xp11.23) and SYN2 (rs2289708, 3'-untranslated region, 3p25) in schizopherenia.

METHODS

Two hundred eighty six schizophrenia patients and 304 control subjects were recruited. SNPs with a know heterozygosity and minor allele frequency (MAF) > 0.1 in Asian populations were selected and genotyped by direct sequencing.

RESULTS

The allelic frequencies of rs1142636 (SYN1) were associated with schizophrenia (P < 0.05), respectively. The allelic frequency of rs1142636 in all subjects was associated with schizophrenia [P = 0.000059, OR = 2.17 (95% CI = 1.47-3.18)]. The C allele frequency of rs1142636 was higher in schizophrenia (20.8%) than that in controls (10.8%). In the analysis of gender, the allelic frequency of rs1142636 was also strongly associated with female schizophrenia [P = 0.0001, OR = 2.65 (95% CI = 1.61-4.36)], but not with male schizophrenia. The C allele frequency of rs1142636 was higher in female schizophrenia (22.2%) than that in female controls (9.7%). The rs2289708 SNP (SYN2) did not show any association between schizophrenia and controls.

CONCLUSIONS

These results suggest that the C allele of a synonymous SNP (rs1142636, Asn170Asn, Xp11.23) in SYN1 may be a risk factor for the susceptibility of Koreran female schizophrenia.

CRP promotes MMP-10 expression via c-Raf/MEK/ERK and JAK1/ERK pathways in cardiomyocytes

C-reactive protein (CRP) was reported to be a predictor for left ventricular (LV) remodeling. Matrix metalloproteinase (MMP)-10 participates in the LV remodeling process. However, the intrinsic relationship between CRP and MMP-10 in cardiomyocytes remains unclear. The purpose of this study is to observe whether CRP may promote MMP-10 expression, and if so, to clarify signaling pathways to be involved in CRP-induced MMP-10 expression in cardiomyocytes. We observed in cultured cardiomyocytes that CRP at a dose of 5 μg/ml increased MMP-10 expression and activity in a time-dependent manner, as measured by real-time polymerase chain reaction (PCR), western blots, and casein zymography analysis. We hypothesized that signal pathways of mitogen-activated protein kinases (MAPKs) and Janus kinases (JAKs)/signal transducers and activators of transcription (STATs) might be involved in CRP-induced MMP-10 expression. Our results showed that CRP markedly activated c-Raf/MEK/ERK and JAK1/ERK signaling pathways but not JAK1/STAT3 signaling pathway by using the phosphor-specific antibodies against these pathways, and blockages of c-Raf/MEK/ERK and JAK1/ERK signaling pathways by the specific ERK1/2 inhibitor U0126 and JAK1 inhibitor piceatannol could significantly decrease CRP-induced MMP-10 expression. In addition, we demonstrated that the DNA binding sites of AP-1 and STAT3 in the nucleus of cardiomyocytes mediated CRP-induced MMP-10 expression. In conclusion, we demonstrated that CRP promoted MMP-10 expression and activity in cardiomyocytes, and clarified that c-Raf/MEK/ERK and JAK1/ERK signaling pathways were involved in MMP-10 expression regulation via activation of DNA binding sites for AP-1 and STAT3 in cardiomyocytes. Our findings suggest that CRP acts as a predictor for LV remodeling might be associated with its promotion effect on MMP-10 expression and activity.

Polymorphisms of genes involved in extracellular matrix remodeling and abdominal aortic aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) has a multifactorial etiology and the relevance of genetic factors is getting increasing interest, in particular those related to the destructive remodeling of extracellular matrix.

METHODS

We performed a candidate gene association study of polymorphisms in genes coding matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and elastin (ELN) in AAA. DNA samples from 423 AAA patients and 423 controls were genotyped for 12 polymorphisms in 10 genes: MMP1 (-1607G/GG), MMP2 (-735C/T; -1306C/T; -1575 G/A), MMP3 (5A/6A), MMP9 (-1562C/T), MMP10 (A180G), MMP-12 (-82A/G), MMP-13 (-77A/G), TIMP1 (C434T), TIMP3 (-1296T/C), and ELN (G1355A).

RESULTS

Genotype distribution was significantly different between patients and controls for the following polymorphisms: -1306C/T MMP2; 5A/6A MMP3; -77A/G MMP-13; G1355A ELN; and C434T TIMP1. In a multivariable logistic regression analysis adjusted for traditional cardiovascular risk factors and chronic obstructive pulmonary disease, -1306C/T MMP2 (odds ratios [OR] = 0.55 [95% confidence interval, CI .34-.85], P < .007) and G1355A ELN (OR = 0.64 ([95% CI .41-.99], P = .046) polymorphisms resulted in independent protective factors for abdominal aortic aneurysm (AAA), whereas 5A/6A MMP3 (OR = 1.82 [95% CI 1.04-3.12], P = .034) and -77 A/G MMP-13 (OR = 2.14 [95% CI 1.18-3.86], P = .012) polymorphisms resulted in independent risk factors for AAA. In a multivariable logistic regression analysis adjusted for traditional cardiovascular factors and chronic obstructive pulmonary disease, the prevalence of the contemporary presence of three or four genetic risk conditions was a strong and independent determinant of AAA disease (OR = 2.96, 95% CI 1.67-5.24, P < .0001). For those polymorphisms independently associated with AAA in this study (-1306C/T MMP2, 5A/6A MMP3, -77A/G MMP-13, and G1355A ELN polymorphisms), we performed a meta-analysis of the available data (this paper and literature data). We found a significant association with an increased risk of AAA for MMP3 (AAA patients n = 1258, controls n = 1406: OR = 1.48 [95% CI = 1.23-1.78], I(2) = 0%) and MMP-13 (AAA patients n = 800, controls n = 843: OR = 1.37 [95% CI = 1.04-1.82], I(2) = 25%) polymorphisms and a trend that did not reach the statistical significance, toward a decreased risk of AAA for MMP2 (AAA patients n = 1090, controls n = 1077: OR = 0.83 [95% CI = .60-1.15], I(2) =7 1%) and ELN (AAA patients n = 904, controls n = 1069: OR = 0.79 [95% CI = .53-1.18], I(2) = 72%) polymorphisms.

CONCLUSIONS

These findings suggest that polymorphisms in MMP2, MMP3, MMP-13, and ELN genes may independently contribute to the pathogenesis of AAA.

Protective effects of angiotensin-converting enzyme I/I and matrix metalloproteinase-3 6A/6A polymorphisms on dilatative pathology within the ascending thoracic aorta

OBJECTIVE

Activation of matrix metalloproteinases and the renin/angiotensin signaling pathways is under investigation with regard to their potential pathogenesis in dilatative pathology of the aorta. The purpose of this study was to explore matrix metalloproteinase-3 5A/6A and angiotensin-converting enzyme I/D polymorphisms as predisposing factors to dilatative pathology of the aorta.

METHODS

We studied 107 patients who underwent aortic reconstruction surgery due to dilatative pathology of ascending thoracic aorta and a random sample of the population (n = 773), all from Lithuania. The insertion/deletion (-1171 5A/6A) polymorphism in the promoter region of matrix metalloproteinase-3 studied by real-time polymerase-chain-reaction amplification and the D and I alleles were identified on the basis of standard polymerase-chain-reaction amplification of the respective fragments from intron 16 of the angiotensin-converting enzyme gene.

RESULTS

The frequency of the angiotensin-converting enzyme D allele was significantly higher in dilatative pathology of ascending thoracic aorta patients than in the reference group subjects (0.55 vs 0.48, respectively). The latter group had a significantly higher frequency of the angiotensin-converting enzyme I/I genotype than in dilatative pathology of ascending thoracic aorta patients (27.4% vs 16.5%, respectively). In the reference group, the frequency of combined angiotensin-converting enzyme I/I and matrix metalloproteinase-3 6A/6A genotypes was 7.5%, while in the dilatative pathology of ascending thoracic aorta patient group, there was no one carrying that combined genotype (p = 0.001).

CONCLUSIONS

The present study showing a role of angiotensin-converting enzyme and matrix metalloproteinase-3 in the development of dilatative pathology of ascending thoracic aorta permits us to entertain a possible protective mechanism for the combined effects of the angiotensin-converting enzyme I/I and the matrix metalloproteinase-3 6A/6A genotypes.

Type-specific dysregulation of matrix metalloproteinases and their tissue inhibitors in end-stage heart failure patients: relationship between MMP-10 and LV remodelling

Although past studies observed the changes of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in end-stage heart failure (HF) patients, a consistent and clear pattern of type-specific MMPs and/or TIMPs has yet to be further defined. In this study, proteomic approach of human protein antibody arrays was used to compare MMP and TIMP expression levels of left ventricular (LV) myocardial samples from end-stage HF patients due to dilated cardiomyopathy (DCM) with those from age- and sex- matched non-failing patients. Western blot analysis, immunohistochemistry and ELISA were used for validation of our results. We observed that MMP-10 and -7 abundance increased, accompanied by decreased TIMP-4 in DCM failing hearts (n= 8) compared with non-failing hearts (n= 8). The results were further validated in a cohort of 34 end-stage HF patients derived from three forms of cardiomyopathies. Cardiac and plasma MMP-10 levels were positively correlated with the LV end-diastolic dimension in this HF cohort. In addition, we observed that insulin-like growth factor-2 promoted MMP-10 production in neonatal rat cardiomyocytes. In conclusion, this study demonstrated a selective up-regulation of MMP-10 and -7 along with a discordant change of TIMP-4, and a positive correlation between MMP-10 levels and the degree of LV dilation in end-stage HF patients. Our findings suggest that type-specific dysregulation of MMPs and TIMPs is associated with LV remodelling in end-stage HF patients, and MMP-10 may act as a novel biomarker for LV remodelling.

Analysis of positional candidate genes in the AAA1 susceptibility locus for abdominal aortic aneurysms on chromosome 19

BACKGROUND

Abdominal aortic aneurysm (AAA) is a complex disorder with multiple genetic risk factors. Using affected relative pair linkage analysis, we previously identified an AAA susceptibility locus on chromosome 19q13. This locus has been designated as the AAA1 susceptibility locus in the Online Mendelian Inheritance in Man (OMIM) database.

METHODS

Nine candidate genes were selected from the AAA1 locus based on their function, as well as mRNA expression levels in the aorta. A sample of 394 cases and 419 controls was genotyped for 41 SNPs located in or around the selected nine candidate genes using the Illumina GoldenGate platform. Single marker and haplotype analyses were performed. Three genes (CEBPG, PEPD and CD22) were selected for DNA sequencing based on the association study results, and exonic regions were analyzed. Immunohistochemical staining of aortic tissue sections from AAA and control individuals was carried out for the CD22 and PEPD proteins with specific antibodies.

RESULTS

Several SNPs were nominally associated with AAA (p < 0.05). The SNPs with most significant p-values were located near the CCAAT enhancer binding protein (CEBPG), peptidase D (PEPD), and CD22. Haplotype analysis found a nominally associated 5-SNP haplotype in the CEBPG/PEPD locus, as well as a nominally associated 2-SNP haplotype in the CD22 locus. DNA sequencing of the coding regions revealed no variation in CEBPG. Seven sequence variants were identified in PEPD, including three not present in the NCBI SNP (dbSNP) database. Sequencing of all 14 exons of CD22 identified 20 sequence variants, five of which were in the coding region and six were in the 3'-untranslated region. Five variants were not present in dbSNP. Immunohistochemical staining for CD22 revealed protein expression in lymphocytes present in the aneurysmal aortic wall only and no detectable expression in control aorta. PEPD protein was expressed in fibroblasts and myofibroblasts in the media-adventitia border in both aneurysmal and non-aneurysmal tissue samples.

CONCLUSIONS

Association testing of the functional positional candidate genes on the AAA1 locus on chromosome 19q13 demonstrated nominal association in three genes. PEPD and CD22 were considered the most promising candidate genes for altering AAA risk, based on gene function, association evidence, gene expression, and protein expression.

Genes and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since the first candidate gene studies were published 20 years ago, approximately 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. These studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, only when appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called contactin-3, which is located on chromosome 3p12.3. However, two follow-up studies could not replicate this association. Two other SNPs, which are located on chromosome 9p21 and 9q33, were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense ribonucleic acid that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute toward AAA pathogenesis.

Abdominal aortic aneurysm: a review of the genetic basis

BACKGROUND

Abdominal aortic aneurysm (AAA) is a complex disease with a largely unknown pathophysiological background and a strong genetic component. Various studies have tried to link specific genetic variants with AAA.

METHODS

Systematic review of the literature (1947-2009).

RESULTS

A total of 249 studies were identified, 89 of which were eventually deemed relevant to this review. Genetic variants (polymorphisms) in a wide variety of genes, most of which encode proteolytic enzymes and inflammatory molecules, have been associated with AAA development and progression.

CONCLUSION

The genetic basis of AAA remains unknown, and most results from ''candidate-gene'' association studies are contradictory. Further analyses in appropriately powered studies in large, phenotypically well-characterized populations, including genome-wide association studies, are necessary to elucidate the exact genetic contribution to the pathophysiology of AAA.

Genetic and epigenetic mechanisms and their possible role in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a common disease associated with significant cardiovascular morbidity and mortality. The pathogenesis of AAA is poorly defined, making targeting of new therapies problematic. Current evidence favours an interaction of multiple environmental and genetic factors in the initiation and progression of AAA. Epigenetics is the term used to define the properties of the genome that are not explained by the primary sequence, but are due to the modifications of DNA and/or associated proteins. Previous research indicates the association of gene specific promoter DNA hyper-methylation and global DNA hypo-methylation with atherosclerosis. Evidence also suggests an important role for epigenetic processes such as histone acetylation in cardiovascular diseases including atherosclerosis and restenosis. Altered DNA methylation or histone acetylation occur in inflammation, cellular proliferation and remodelling processes and therefore maybe relevant to the pathology of AAA. Important risk factors for AAA, including cigarette smoking, older age, male gender and hypertension, have been linked with epigenetic effects and thus could act in this way to promote AAA. In this review, we discuss the potential role of epigenetic mechanisms in AAA. Since epigenetic alterations are to some extent reversible, further study of this area may identify new treatment targets for AAA.

Matrix metalloproteinase-9, -10, and tissue inhibitor of matrix metalloproteinases-1 blood levels as biomarkers of severity and mortality in sepsis

Introduction

Matrix metalloproteinases (MMPs) play a role in infectious diseases through extracellular matrix (ECM) degradation, which favors the migration of immune cells from the bloodstream to sites of inflammation. Although higher levels of MMP-9 and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) have been found in small series of patients with sepsis, MMP-10 levels have not been studied in this setting. The objective of this study was to determine the predictive value of MMP-9, MMP-10, and TIMP-1 on clinical severity and mortality in a large series of patients with severe sepsis.

Methods

This was a multicenter, observational, and prospective study carried out in six Spanish Intensive Care Units. We included 192 (125 surviving and 67 nonsurviving) patients with severe sepsis and 50 age- and sex-matched healthy controls in the study. Serum levels of MMP-9, MMP-10, TIMP-1, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-10 were measured in patients with severe sepsis at the time of diagnosis and in healthy controls.

Results

Sepsis patients had higher levels of MMP-10 and TIMP-1, higher MMP-10/TIMP-1 ratios, and lower MMP-9/TIMP-1 ratios than did healthy controls (P < 0.001). An association was found between MMP-9, MMP-10, TIMP-1, and MMP-9/TIMP-1 ratios and parameters of sepsis severity, assessed by the SOFA score, the APACHE-II score, lactic acid, platelet count, and markers of coagulopathy. Nonsurviving sepsis patients had lower levels of MMP-9 (P = 0.037), higher levels of TIMP-1 (P < 0.001), lower MMP-9/TIMP-1 ratio (P = 0.003), higher levels of IL-10 (P < 0.001), and lower TNF-α/IL-10 ratio than did surviving patients. An association was found between MMP-9, MMP-10, and TIMP-1 levels, and TNF-α and IL-10 levels. The risk of death in sepsis patients with TIMP-1 values greater than 531 ng/ml was 80% higher than that in patients with lower values (RR = 1.80; 95% CI = 1.13 to 2.87;P = 0.01; sensitivity = 0.73; specificity = 0.45).

Conclusions

The novel findings of our study on patients with severe sepsis (to our knowledge, the largest series reporting data about MMP levels in sepsis) are that reduced MMP-9/TIMP-1 ratios and increased MMP-10 levels may be of great pathophysiologic significance in terms of severity and mortality, and that TIMP-1 levels may represent a biomarker to predict the clinical outcome of patients with sepsis.

Association of the TGF-beta receptor genes with abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial condition. The transforming growth factor beta (TGF-beta) pathway regulates vascular remodeling and mutations in its receptor genes, TGFBR1 and TGFBR2, cause syndromes with thoracic aortic aneurysm (TAA). The TGF-beta pathway may be involved in aneurysm development in general. We performed an association study by analyzing all the common genetic variants in TGFBR1 and TGFBR2 using tag single nucleotide polymorphisms (SNPs) in a Dutch AAA case-control population in a two-stage genotyping approach. In stage 1, analyzing 376 cases and 648 controls, three of the four TGFBR1 SNPs and nine of the 28 TGFBR2 SNPs had a P<0.07. Genotyping of these SNPs in an independent cohort of 360 cases and 376 controls in stage 2 confirmed association (P<0.05) for the same allele of one SNP in TGFBR1 and two SNPs in TGFBR2. Joint analysis of the 736 cases and 1024 controls showed statistically significant associations of these SNPs, which sustained after proper correction for multiple testing (TGFBR1 rs1626340 OR 1.32 95% CI 1.11-1.56 P=0.001 and TGFBR2 rs1036095 OR 1.32 95% CI 1.12-1.54 P=0.001 and rs4522809 OR 1.28 95% CI 1.12-1.46 P=0.0004). We conclude that genetic variations in TGFBR1 and TGFBR2 associate with AAA in the Dutch population. This suggests that AAA may develop partly by similar defects as TAA, which in the future may provide novel therapeutic options.

Association between matrix metalloproteinase-10 concentration and smoking in individuals without cardiovascular disease

INTRODUCTION AND OBJECTIVES

Smoking is an important cardiovascular risk factor whose underlying mechanism is incompletely understood. However, it has been suggested that alterations in the balance between synthesis and degradation of the extracellular matrix (ECM) may play a role. The aim of this study was to determine whether there is an independent association between smoking and the concentration of circulating metalloproteinases (MMPs) in individuals without cardiovascular disease.

METHODS

Metabolic parameters, the carotid intima-media thickness (IMT), inflammatory markers (fibrinogen, C-reactive protein and interleukin-6), markers of endothelial damage (e.g., von Willebrand factor), and the concentration of MMP-1, -9 and -10 and tissue inhibitor of metalloproteinase-1 (TIMP-1) were assessed in 400 asymptomatic individuals with cardiovascular risk factors. Subjects were divided into non-smokers (n=195), smokers (n=118) and former smokers (n=87). In addition, global cardiovascular risk was determined from PROCAM and REGICOR scores.

RESULTS

Both MMP-1 and MMP-10 concentrations were significantly higher in smokers than non-smokers (P< .05 and P< .001, respectively), though there was no difference in the levels of MMP-9, TIMP-1, IMT and other inflammatory parameters. There were positive correlations between the MMP-10 concentration and PROCAM and REGICOR scores (P< .001). Multivariate analysis showed that there was still an association between smoking and the MMP-10 concentration after adjustment for age, sex and other cardiovascular risk factors (P< .001). Multiple regression analysis showed that smoking accounted for 28% of the variability in the MMP-10 concentration.

CONCLUSIONS

There was an independent association between smoking and the MMP-10 concentration in asymptomatic individuals. This relationship between MMP-10 and the ECM may indicate a mechanism through which this MMP contributes to smoking-related atherosclerosis.

No association of MMP-7, MMP-8, and MMP-21 polymorphisms with the risk of hepatocellular carcinoma in a Chinese population

Previous studies have suggested that the functional polymorphisms in the promoters of matrix metalloproteinases (MMP) genes were associated with the risk of cancers, but no study has ever explored these polymorphisms as risk factors for hepatocellular carcinoma. Recently, we firstly examined whether seven functional polymorphisms in the promoters of MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, and MMP-13 have any bearing on the risk of hepatocellular carcinoma, but we found none. In this study, we focused on an additional six MMP polymorphisms, including four functional polymorphisms in the promoters of MMP-7 (A-181G and C-153T) and MMP-8 (C-799T and A-381G), and two nonsynonymous polymorphisms in MMP-10 (A180G) and MMP-21 (C572T). With the polymorphism validation, we found that only MMP-7 A-181G, MMP-8 C-799T, and MMP-21 C572T were polymorphic. These three polymorphisms were then genotyped in 434 patients with hepatocellular carcinoma and 480 controls by PRC-RFLP analysis. The associations between the polymorphisms and hepatocellular carcinoma risk were evaluated while controlling for confounding factors. No significant association with the risk of hepatocellular carcinoma was observed with the three polymorphisms in the overall sample, hepatitis B virus carriers, and non-hepatitis B virus carriers after correction for multiple comparisons. Furthermore, when the analyses were stratified by age, sex, status of smoking and drinking, pack-years of smoking, and family history of hepatocellular carcinoma, there was also no significant association between these polymorphisms and hepatocellular carcinoma risk. Our findings suggest that the polymorphisms MMP-7 A-181G, MMP-8 C-799T, and MMP-21 C572T may not play a major role in mediating susceptibility to hepatocellular carcinoma.