Medical management of small abdominal aortic aneurysms

Recombinant human thrombomodulin suppresses experimental abdominal aortic aneurysms induced by calcium chloride in mice

OBJECTIVE

To investigate whether recombinant thrombomodulin containing all the extracellular domains (rTMD123) has therapeutic potential against aneurysm development.

SUMMARY BACKGROUND DATA

The pathogenesis of abdominal aortic aneurysm (AAA) is characterized by chronic inflammation and proteolytic degradation of extracellular matrix. Thrombomodulin, a transmembrane glycoprotein, exerts anti-inflammatory activities such as inhibition of cytokine production and sequestration of proinflammatory high-mobility group box 1 (HMGB1) to prevent it from engaging the receptor for advanced glycation end product (RAGE) that may sustain inflammation and tissue damage.

METHODS

The in vivo effects of treatment and posttreatment with rTMD123 on aortic dilatation were measured using the CaCl2-induced AAA model in mice.

RESULTS

Characterization of the CaCl2-induced model revealed that HMGB1 and RAGE, both localized mainly to macrophages, were persistently upregulated during a 28-day period of AAA development. In vitro, rTMD123-HMGB1 interaction prevented HMGB1 binding to macrophages, thereby prohibiting activation of HMGB1-RAGE signaling in macrophages. In vivo, short-term treatment with rTMD123 upon AAA induction suppressed the levels of proinflammatory cytokines, HMGB1, and RAGE in the aortic tissue; reduced the infiltrating macrophage number; and finally attenuated matrix metalloproteinase production, extracellular matrix destruction, and AAA formation without disturbing vascular calcification. Consistently, posttreatment with rTMD123 seven days after AAA induction alleviated vascular inflammation and retarded AAA progression.

CONCLUSIONS

These data suggest that rTMD123 confers protection against AAA development. The mechanism of action may be associated with reduction of proinflammatory mediators, blockade of macrophage recruitment, and suppression of HMGB1-RAGE signaling involved in aneurysm formation and downstream macrophage activation.

Statins Promote Residual Aneurysm Sac Regression Following Endovascular Aortic Aneurysm Repair

Background:

Regression of the residual sac is indicative of successful endovascular aortic aneurysm (EVAR) repair. Using color duplex ultrasound (CDU), we monitored the residual aneurysm sac following EVAR and correlated sac behavior with perioperative risk factors.

Methods:

Of 145 patients with EVAR, 106 (73.1%) patients between January 01, 2003, and July 01, 2010, had at least 2 consecutive postoperative scans and thus were eligible for inclusion. Mean (± standard deviation [SD]) CDU scans per person was 4.6 (±1.4). All were conducted by the same technologist using a standard protocol on the same machine. Aneurysm sac change in centimeters and percentage terms was calculated. The presence or absence of an endoleak was also recorded. Change in aneurysm sac size was correlated with preoperative risk factors.

Findings:

Mean sac size change at 1 month was a decrease of 0.24 cm, equating to a percentage change of 4.3%. At 7 months, the decrease was 0.59 cm (9.8%), at 12 months, 0.73 cm (12.4%), at 18 months 0.92 cm (15.8%), and at 36 months 1.0 cm (16.6%). Both univariate and multivariate analyses demonstrated that statin therapy ( P = .002) was the only risk factor variable positively associated with aneurysm regression while the presence of an endoleak was inversely related to sac reduction ( P = .01).

Interpretation:

Maximum aneurysmal sac reduction seems to occur in the first year following endograft implantation. Statin therapy appears to be associated with an increased likelihood of sac regression following EVAR. Further investigation of the role of statins in the biology of abdominal aortic aneurysmal disease is warranted.

Role of the renin-angiotensin system on abdominal aortic aneurysms

BACKGROUND

Abdominal aortic aneurysm (AAA) is a complex degenerative disease, which leads to morbidity and mortality in a large portion of the elderly population. Current treatment options for AAA are quite limited as there is no proven indication for pharmacological therapy and surgery is recommended for AAA larger than 5·5 cm in luminal diameter. Thus, there is a great need to elucidate the underlying pathophysiological cellular and molecular mechanisms to develop effective therapies. In this narrative review, we will discuss recent findings concerning some potential molecular and clinical aspects of the renin-angiotensin system (RAS) in AAA pathophysiology.

MATERIALS AND METHODS

This narrative review is based on the material found on MEDLINE and PubMed up to April 2013. We looked for the terms 'angiotensin, AT1 receptor, ACE inhibitors' in combination with 'abdominal aortic aneurysm, pathophysiology, pathways'.

RESULTS

Several basic research and clinical studies have recently investigated the role of the RAS in AAA. In particular, the subcutaneous infusion of Angiotensin II has been shown to induce AAA in Apo56 knockout mice. On the other hand, the pharmacological treatments targeting this system have been shown as beneficial in AAA patients.

CONCLUSIONS

Emerging evidence suggests that RAS may act as a molecular and therapeutic target for treating AAA. However, several issues on the role of RAS and the protective activities of angiotensin-converting enzyme (ACE) inhibitors and Angiotensin 1 receptors blockers against AAA require further clarifications.

Inhibition of rho-kinase by fasudil suppresses formation and progression of experimental abdominal aortic aneurysms

Objective

Accumulating evidence suggests that inflammatory cell infiltration is crucial pathogenesis during the initiation and progression of abdominal aortic aneurysm (AAA). Given Rho-kinase (ROCK), an important kinase control the actin cytoskeleton, regulates the inflammatory cell infiltration, thus, we investigate the possibility and mechanism of preventing experimental AAA progression via targeting ROCK in mice porcine pancreatic elastase (PPE) model.

Methods and Results

AAA was created in 10-week-old male C57BL/6 mice by transient intraluminal porcine pancreatic elastase infusion into the infrarenal aorta. The mRNA level of RhoA, RhoC, ROCK1 and ROCK2 were elevated in aneurismal aorta. Next, PPE infusion mice were orally administrated with vehicle or ROCK inhibitor (Fasudil at dose of 200 mg/kg/day) during the period of day 1 prior to PPE infusion to day 14 after PPE infusion. PPE infusion mice treated with Fasudil produced significantly smaller aneurysms as compare to PPE infusion mice treated with vehicle. AAAs developed in all vehicle-treated groups within 14 days, whereas AAAs developed in six mice (66%, 6/9) treated with Fasudil within 14 days. Furthermore, our semi-quantitative histological analysis revealed that blood vessels and macrophages were significantly reduced in Fasudil treated mice during the AAA progression. Finally, when mice with existing AAAs were treated with Fasudil, the enlargement was nearly completely suppressed.

Conclusion

Fasudil inhibits experimental AAA progression and stabilize existing aneurysms, through mechanisms likely related to impaired mural macrophage infiltration and angiogenesis. These findings suggest that ROCK inhibitor may hold substantial translational value for AAA diseases.

Current status of medical treatment for abdominal aortic aneurysm

Although cardiovascular disease is widely recognized as the leading cause of death, a lesser known fact is that aortic aneurysm is the 15th leading cause of death over the age of 65 years in the USA. The golden standard of the treatments are invasive interventions either with open surgical repair (OS) or endovascular aneurysm repair (EVAR). The concept of medical treatment is to prevent abdominal aortic aneurysm (AAA) from rupture and avoid surgical treatment by preventing aneurysm enlargement or even reducing aneurysm size. Matrix metalloproteinases (MMP) are structurally related metalloendopeptidases that can degrade the extracellular matrix and is thought to play important roles in AAA. There are many proposed pharmacological treatments including: β-blockers, angiotensin-converting enzyme inhibitor (ACE inhibitors), angiotensin-receptor blocker (ARB), statins, macrolides and, doxycycline, an inhibitor of the MMP. The latter is a potential promising drug as medical treatment for AAA and the Non-invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA(3)CT) is currently ongoing in the USA. Here, the pathophysiology and potential medical therapy for AAA will be reviewed.

Lessons from Animal Models of Arterial Aneurysm

We review the results from the most common animal models of arterial aneurysm, including recent findings from our novel, laparoscopy-based pig model of abdominal aortic aneurysm, that contribute important insights into early pathogenesis. We emphasize the relevance of these findings for evaluation of treatment protocols and novel device prototypes for mechanism-based prevention of progression and rupture.

Combination therapy with atorvastatin and amlodipine suppresses angiotensin II-induced aortic aneurysm formation

Background

Abdominal aortic aneurysm (AAA) is a life-threatening vascular disease. It is controversial whether statin and calcium channel blockers (CCBs) has an inhibitory effect on the expansion of AAA. Some studies reported that CCBs have an inhibitory effect on Rho-kinase activity. Rho-kinase plays an important role in the pathogenesis of various cardiovascular diseases. However, there is no study reporting of the association between Rho-kinase and human AAAs.

Methods and Results

Experimental AAA was induced in Apolipoprotein E-deficient (ApoE^-/-) mice infused with angiotensin II (AngII) for 28 days. They were randomly divided into the following 5 groups; saline infusion alone (sham), AngII infusion alone, AngII infusion plus atorvastatin (10 mg/kg/day), AngII infusion plus amlodipine (1 mg/kg/day), and AngII infusion plus combination therapy with atorvastatin (10 mg/kg/day) and amlodipine (1 mg/kg/day). The combination therapy significantly suppressed AngII-induced increase in maximal aortic diameter as compared with sham, whereas each monotherapy had no inhibitory effects. The combination therapy significantly reduced AngII-induced apoptosis and elastin degradation at the AAA lesion, whereas each monotherapy did not. Moreover, Rho-kinase activity, as evaluated by the extent of phosphorylation of myosin-binding subunit (a substrate of Rho-kinase) and matrix metalloproteinase activity were significantly increased in the AngII-induced AAA lesion as compared with sham, both of which were again significantly suppressed by the combination therapy. In human aortic samples, immunohistochemistory revealed that the activity and expression of Rho-kinase was up-regulated in AAA lesion as compared with abdominal aorta from control subjects.

Conclusions

Rho-kinase is up-regulated in the aortic wall of human AAA. The combination therapy with amlodipine and Atorvastatin, but not each monotherapy, suppresses AngII-induced AAA formation in mice in vivo, for which Rho-kinase inhibition may be involved.

Intravenous administration of mesenchymal stem cells prevents angiotensin II-induced aortic aneurysm formation in apolipoprotein E-deficient mouse

Background

Mesenchymal stem cells (MSCs) are known to be capable of suppressing inflammatory responses. We previously reported that intra-abdominal implantation of bone marrow-derived MSCs (BM-MSCs) sheet by laparotomy attenuated angiotensin II (AngII)-induced aortic aneurysm (AA) growth in apolipoprotein E-deficient (apoE^−/−) mice through anti-inflammation effects. However, cell delivery by laparotomy is invasive; we here demonstrated the effects of multiple intravenous administrations of BM-MSCs on AngII-induced AA formation.

Methods

BM-MSCs were isolated from femurs and tibiae of male apoE^−/− mice. Experimental AA was induced by AngII infusion for 28 days in apoE^−/− mice. Mice received weekly intravenous administration of BM-MSCs (n=12) or saline (n=10). After 4 weeks, AA formation incidence, aortic diameter, macrophage accumulation, matrix metalloproteinase (MMP)’ activity, elastin content, and cytokines were evaluated.

Results

AngII induced AA formation in 100% of the mice in the saline group and 50% in the BM-MSCs treatment group (P < 0.05). A significant decrease of aortic diameter was observed in the BM-MSCs treatment group at ascending and infrarenal levels, which was associated with decreased macrophage infiltration and suppressed activities of MMP-2 and MMP-9 in aortic tissues, as well as a preservation of elastin content of aortic tissues. In addition, interleukin (IL)-1β, IL-6, and monocyte chemotactic protein-1 significantly decreased while insulin-like growth factor-1 and tissue inhibitor of metalloproteinases-2 increased in the aortic tissues of BM-MSCs treatment group.

Conclusions

Multiple intravenous administrations of BM-MSCs attenuated the development of AngII-induced AA in apoE^−/− mice and may become a promising alternative therapeutic strategy for AA progression.

β-Carotene Attenuates Angiotensin II-Induced Aortic Aneurysm by Alleviating Macrophage Recruitment in Apoe(-/-) Mice

Abdominal aortic aneurysm (AAA) is a common chronic degenerative disease characterized by progressive aortic dilation and rupture. The mechanisms underlying the role of α-tocopherol and β-carotene on AAA have not been comprehensively assessed. We investigated if α-tocopherol and β-carotene supplementation could attenuate AAA, and studied the underlying mechanisms utilized by the antioxidants to alleviate AAA. Four-months-old Apoe^−/− mice were used in the induction of aneurysm by infusion of angiotensin II (Ang II), and were orally administered with α-tocopherol and β-carotene enriched diet for 60 days. Significant increase of LDL, cholesterol, triglycerides and circulating inflammatory cells was observed in the Ang II-treated animals, and gene expression studies showed that ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9 and MMP-12 were upregulated in the aorta of aneurysm-induced mice. Extensive plaques, aneurysm and diffusion of inflammatory cells into the tunica intima were also noticed. The size of aorta was significantly (P = 0.0002) increased (2.24±0.20 mm) in the aneurysm-induced animals as compared to control mice (1.17±0.06 mm). Interestingly, β-carotene dramatically controlled the diffusion of macrophages into the aortic tunica intima, and circulation. It also dissolved the formation of atheromatous plaque. Further, β-carotene significantly decreased the aortic diameter (1.33±0.12 mm) in the aneurysm-induced mice (β-carotene, P = 0.0002). It also downregulated ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9, MMP-12, PPAR-α and PPAR-γ following treatment. Hence, dietary supplementation of β-carotene may have a protective function against Ang II-induced AAA by ameliorating macrophage recruitment in Apoe^−/− mice.

Effectiveness of cyclooxygenase-2 inhibition in limiting abdominal aortic aneurysm progression in mice correlates with a differentiated smooth muscle cell phenotype

Abdominal aortic aneurysms (AAAs) are a chronic condition that often progress over years to produce a weakened aorta with increased susceptibility for rupture, and currently, there are no pharmacological treatments available to slow disease progression. AAA development has been characterized by increased expression of cyclooxygenase-2 (COX-2), and inactivation of COX-2 before disease initiation reduces AAA incidence in a mouse model of the disease. The current study determined the effectiveness of COX-2 inhibition on AAA progression when treatment was begun after initiation of the disease. COX-2 inhibitor treatment with celecoxib was initiated after angiotensin II-induced AAA formation in a strain of nonhyperlipidemic mice that we have previously identified as highly susceptible to AAA development. When analyzed at different time points during progression of the disease, celecoxib treatment significantly reduced the incidence and severity of AAAs. The celecoxib treatment also protected the mice from aortic rupture and death. The aneurysmal lesion displayed an altered smooth muscle cell (SMC) phenotype, whereas celecoxib treatment was associated with increased expression of differentiated SMC markers and reduced dedifferentiation marker expression during AAA progression. Maintenance of a differentiated SMC phenotype is associated with the effectiveness of COX-2 inhibition for limiting AAA progression in nonhyperlipidemic mice.

Statin use and risk of cerebral aneurysm rupture: a hospital-based case-control study in Japan

BACKGROUND

Recent reports have showed that some statins have protective effects in experimental cerebral aneurysm models. We conducted a case-control study to investigate an association between statin use and the rupture risk of cerebral aneurysm in Japanese population.

METHODS

This was a multihospital case-control study; cases and controls were collected from 15 hospitals in Japan. Cases consisted of patients with aneurysmal subarachnoid hemorrhage hospitalized from April 2009 to March 2011. Controls were selected from patients who had newly diagnosed unruptured saccular aneurysms from April 2006 to March 2011. The primary exposure of interest was statin use. Multivariable logistic regression was used to assess the relationship between stain use and the rupture risk of cerebral aneurysm.

RESULTS

A total of 117 cases and 304 controls were included in the analyses. Statin was used in 9.4% of cases and 26.0% of controls. Controls had a significantly higher rate of use of statin. The use of any statin was associated with cerebral aneurysm rupture after adjustment of potential confounders (adjusted odds ratio: .30, 95% confidence interval: .14-.66). The association was similar in each stratum of total cholesterol level.

CONCLUSIONS

This observation from a hospital-based case-control study in Japan suggested that there is inverse relationship between use of statins and cerebral aneurysm rupture. Future clinical studies are needed.

[Treatment of abdominal aortic aneurysms]

The treatment of abdominal aortic aneurysms (AAA) has changed significantly since the introduction of endovascular aortic repair (EVAR). In terms of perioperative morbidity and mortality, randomized multicenter trials revealed results in favour of EVAR compared to open reconstruction. However, EVAR is associated with possible late complications caused by endoleaks, stent migration, kinking and/or overstenting of side branches, making life-long follow-up necessary. Since the majority of patients requiring therapy are elderly and exhibit attendant comorbidities, EVAR has become the procedure of choice in those patients with favourable anatomy. Medicamentous and conservative treatment may be relevant in patients with small to medium-sized aneurysms. Since smoking is one of the major risk factors for the development of AAA, all patients should be advised to stop smoking. Studies on long-term statin therapy in patients following surgical AAA repair showed a reduction in both overall and cardiovascular mortality; AAA patients should therefore receive statins for secondary prevention.

Peptide inhibitor of CXCL4-CCL5 heterodimer formation, MKEY, inhibits experimental aortic aneurysm initiation and progression

OBJECTIVE

Macrophages are critical contributors to abdominal aortic aneurysm (AAA) disease. We examined the ability of MKEY, a peptide inhibitor of CXCL4-CCL5 interaction, to influence AAA progression in murine models.

APPROACH AND RESULTS

AAAs were created in 10-week-old male C57BL/6J mice by transient infrarenal aortic porcine pancreatic elastase infusion. Mice were treated with MKEY via intravenous injection either (1) before porcine pancreatic elastase infusion or (2) after aneurysm initiation. Immunostaining demonstrated CCL5 and CCR5 expression on aneurysmal aortae and mural monocytes/macrophages, respectively. MKEY treatment partially inhibited migration of adaptively transferred leukocytes into aneurysmal aortae in recipient mice. Although all vehicle-pretreated mice developed AAAs, aneurysms formed in only 60% (3/5) and 14% (1/7) of mice pretreated with MKEY at 10 and 20 mg/kg, respectively. MKEY pretreatment reduced aortic diameter enlargement, preserved medial elastin fibers and smooth muscle cells, and attenuated mural macrophage infiltration, angiogenesis, and aortic metalloproteinase 2 and 9 expression after porcine pancreatic elastase infusion. MKEY initiated after porcine pancreatic elastase infusion also stabilized or reduced enlargement of existing AAAs. Finally, MKEY treatment was effective in limiting AAA formation after angiotensin II infusion in apolipoprotein E-deficient mice.

CONCLUSIONS

MKEY suppresses AAA formation and progression in 2 complementary experimental models. Peptide inhibition of CXCL4-CCL5 interactions may represent a viable translational strategy to limit progression of human AAA disease.

Is the abdominal aortic aneurysm rupture rate decreasing?

Decreased smoking has likely had the most significant impact on reducing the prevalence of AAAs. In a review of public data in England and Wales, Anjum and colleagues illustrated a reduction of AAA rupture from 1997 to2009 across all ages attributed to a concurrent decrease in prevalence of smoking. This trend has also been noted in a meta-analysis from Sweeting and colleagues and attributed to a reduction in the prevalence of smoking since the mid-1970s along with an enhanced awareness of cardiovascular risk factor reduction and selective aneurysm screening. Along with an effort to reduce AAA progression and rupture, tools to predict patient-specific risk of AAA rupture are evolving with refined models that incorporate both aneurysm wall stress and wall strength likely to provide the most promising approach. Although the role of statins, ACE inhibitors, beta-blockers, and aspirin in preventing or slowing aneurysmal rupture remains unresolved, their proven benefit in reducing long-term cardiovascular mortality suggests that these medications should be considered in any patient with a small AAA. Currently, randomized trials do not show any survival benefit for open or endovascular repair for small aneurysms in the range of 4.0 to 5.4 cm. AAA repair, whether through an endovascular or open approach, is not without potential complication. Even at centers of excellence, the 30-day mortality rate for conventional AAA surgery is 3% to 5%, with rates of major morbidityranging from 15% to 40%. The Society for Vascular Surgery guidelines recommends surveillance for patients with a fusiform AAA of 4.0 to 5.4 cm. The risk of AAA rupture appears to be decreasing through heightened public awareness, advanced technology for AAA detection, screening and surveillance, improved understanding of biomechanics and natural progression in AAA rupture, along with the availability of a wide range of medical therapies for risk factor reduction and minimally invasive options for AAA repair.

Efficacy and mechanism of angiotensin II receptor blocker treatment in experimental abdominal aortic aneurysms

Background

Despite the importance of the renin-angiotensin (Ang) system in abdominal aortic aneurysm (AAA) pathogenesis, strategies targeting this system to prevent clinical aneurysm progression remain controversial and unproven. We compared the relative efficacy of two Ang II type 1 receptor blockers, telmisartan and irbesartan, in limiting experimental AAAs in distinct mouse models of aneurysm disease.

Methodology/Principal Findings

AAAs were induced using either 1) Ang II subcutaneous infusion (1000 ng/kg/min) for 28 days in male ApoE^−/− mice, or 2) transient intra-aortic porcine pancreatic elastase infusion in male C57BL/6 mice. One week prior to AAA creation, mice started to daily receive irbesartan (50 mg/kg), telmisartan (10 mg/kg), fluvastatin (40 mg/kg), bosentan (100 mg/kg), doxycycline (100 mg/kg) or vehicle alone. Efficacy was determined via serial in vivo aortic diameter measurements, histopathology and gene expression analysis at sacrifice. Aortic aneurysms developed in 67% of Ang II-infused ApoE^−/− mice fed with standard chow and water alone (n = 15), and 40% died of rupture. Strikingly, no telmisartan-treated mouse developed an AAA (n = 14). Both telmisartan and irbesartan limited aneurysm enlargement, medial elastolysis, smooth muscle attenuation, macrophage infiltration, adventitial neocapillary formation, and the expression of proteinases and proinflammatory mediators. Doxycycline, fluvastatin and bosentan did not influence aneurysm progression. Telmisartan was also highly effective in intra-aortic porcine pancreatic elastase infusion-induced AAAs, a second AAA model that did not require exogenous Ang II infusion.

Conclusion/Significance

Telmisartan suppresses experimental aneurysms in a model-independent manner and may prove valuable in limiting clinical disease progression.

Opportunities in abdominal aortic aneurysm research: epidemiology, genetics, and pathophysiology

Aortic aneurysms are a complex genetic disorder with known environmental risk factors such as smoking. Along the length of the aorta, significant heterogeneity occurs in the distribution of aneurysmal disease. The prevalence of aneurysm in the abdominal aorta is at least nine times higher than that in the thoracic section of the aorta. A number of studies have shown that aortic aneurysms are frequently familial, even when they are not associated with rare heritable disorders such as Marfan syndrome or Ehlers-Danlos syndrome type IV. The pathobiology of aortic aneurysms is complex and largely unsolved. Unbiased whole-genome approaches are now being used to elucidate the genetic basis of aortic aneurysms to uncover the germline genetic variants that influence the disease risk. The findings will provide critical information about underlying biology of the disease and will help identify potential targets for pharmacological therapies. These studies may lead to therapies that may increase survival rates for individuals with aortic aneurysms and reduce the need for surgical interventions. Abdominal aortic aneurysms were the topic of an international conference "Abdominal Aortic Aneurysm: Epidemiology, Genetics, and Pathophysiology" held recently at the Geisinger Clinic, Danville, Pennsylvania.

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.

Standardization of outcome measures in clinical trials of pharmacological treatment for abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) is a common aortic wall disease with an increased prevalence in the elderly population (4-8% for those aged >65 years). Many AAAs are slow growing and remain insidious. Current standard of care for patients with small AAAs (<49 mm) is surveillance, with interventional therapy (open surgical repair or endovascular aneurysm repair) recommended for large (>50-55 mm), rapidly growing (>10 mm/year) or symptomatic AAAs. Although open surgical repair or endovascular aneurysm repair are effective, significant short- and long-term postoperative morbidity and mortality occurs. Currently, there is no pharmacological treatment specific for AAA; the need for the development of targeted pharmacological therapies based on clinically relevant and feasible outcomes acceptable to the medical community, regulatory agencies and third-party payers is high. A consensus on such end points will be critical to accelerating the development of pharmacological agents to prevent formation, arrest the expansion and reduce the rupture risk of AAA.

Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation

OBJECTIVE

Activation of inflammatory pathways plays a critical role in the development of abdominal aortic aneurysms (AAA). Notch1 signaling is a significant regulator of the inflammatory response; however, its role in AAA is unknown.

METHODS AND RESULTS

In an angiotensin II-induced mouse model of AAA, activation of Notch1 signaling was observed in the aortic aneurysmal tissue of Apoe(-/-) mice, and a similar activation of Notch1 was observed in aneurysms of humans undergoing AAA repair. Notch1 haploinsufficiency significantly reduced the incidence of AAA in Apoe(-/-) mice in response to angiotensin II. Reconstitution of bone marrow-derived cells from Notch1(+/-);Apoe(-/-) mice (donor) in lethally irradiated Apoe(-/-) mice (recipient) decreased the occurrence of aneurysm. Flow cytometry and immunohistochemistry demonstrated that Notch1 haploinsufficiency prevented the influx of inflammatory macrophages at the aneurysmal site by causing defects in macrophage migration and proliferation. In addition, there was an overall reduction in the inflammatory burden in the aorta of the Notch1(+/-);Apoe(-/-) mice compared with the Apoe(-/-) mice. Last, pharmacological inhibition of Notch1 signaling also prevented AAA formation and progression in Apoe(-/-) mice.

CONCLUSIONS

Our data suggest that decreased levels of Notch1 protect against the formation of AAA by preventing macrophage recruitment and attenuating the inflammatory response in the aorta.

Doxycycline does not influence established abdominal aortic aneurysms in angiotensin II-infused mice

Background

There is no proven medical approach to attenuating expansion and rupture of abdominal aortic aneurysms (AAAs). One approach that is currently being investigated is the use of doxycycline. Despite being primarily used as an antimicrobial drug, doxycycline has been proposed to function in reducing AAA expansion. Doxycycline is effective in reducing the formation in the most commonly used mouse models of AAAs when administered prior to the initiation of the disease. The purpose of the current study was to determine the effects of doxycycline on established AAAs when it was administered at a dose that produces therapeutic serum concentrations.

Methods and Results

LDL receptor −/− male mice fed a saturated-fat supplemented diet were infused with AngII (1,000 ng/kg/min) via mini-osmotic pumps for 28 days. Upon verification of AAA formation by noninvasive high frequency ultrasonography, mice were stratified based on aortic lumen diameters, and continuously infused with AngII while also administered either vehicle or doxycycline (100 mg/kg/day) in drinking water for 56 days. Administration of doxycycline led to serum drug concentrations of 2.3±0.6 µg/ml. Doxycycline administration had no effect on serum cholesterol concentrations and systolic blood pressures. Doxycycline administration did not prevent progressive aortic dilation as determined by temporal measurements of lumen dimensions using high frequency ultrasound. This lack of effect on AAA regression and progression was confirmed at the termination of the study by ex vivo measurements of maximal width of suprarenal aortas and AAA volumes. Also, doxycycline did not reduce AAA rupture. Medial and adventitial remodeling was not overtly changed by doxycycline as determined by immunostaining and histological staining.

Conclusions

Doxycycline administration did not influence AngII-induced AAA progression and aortic rupture when administered to mice with established AAAs.

Medical treatment for small abdominal aortic aneurysms

BACKGROUND

Screening for abdominal aortic aneurysm (AAA) in selected groups is now performed in England, the USA and Sweden. Patients with aneurysms over 55 mm in diameter are generally considered for elective surgical repair. Patients with aneurysm diameters below or equal to 55 mm (termed 'small AAAs') are managed with aneurysm surveillance as there is currently insufficient evidence to recommend surgery in these cases. As more patients are screened, there will be an increasing number of small AAAs identified. There is interest in pharmaceutical interventions (for example angiotensin converting enzyme (ACE) inhibitors, antibiotics, beta-blockers, statins) which could be given to such patients to delay or reverse aneurysm expansion and reduce the need for elective surgical repair.

OBJECTIVES

To assess the effects of medical treatment on the expansion rate of small abdominal aortic aneurysms.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (May 2012) and CENTRAL (2012, Issue 5). Clinical trials databases were searched for details of ongoing or unpublished studies. The reference lists of articles retrieved by electronic searches were searched for additional citations.

SELECTION CRITERIA

We selected randomised trials in which patients with small AAAs allocated to medical treatment with the intention of retarding aneurysm expansion were compared to patients allocated to a placebo treatment, alternative medical treatment, a different regimen of the same drug or imaging surveillance alone.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the risk of bias in the trials. Meta-analyses were used when heterogeneity was considered low. The two primary outcomes were the mean difference (MD) in aneurysm diameter and the odds ratio (OR) calculated to compare the number of individuals referred to AAA surgery in each group over the trial period.

MAIN RESULTS

Seven trials involving 1558 participants were included in this review; 457 were involved in four trials of antibiotic medication, and 1101 were involved in three trials of beta-blocker medication. Five of the studies were rated at a high risk of bias.Individually, all of the included trials reported non-significant differences in AAA expansion rates between their intervention and control groups.The two major drug groups were then analysed separately. For AAA expansion it was only possible to combine two of the antibiotic trials in a meta-analysis. This demonstrated that roxithromycin had a small but significant protective effect (MD -0.86 mm; 95% confidence interval (CI) -1.57 to -0.14). When referral to AAA surgery was compared (including all four antibiotic trials in the meta-analysis), non-significantly fewer patients were referred in the intervention groups (OR 0.96; 95% CI 0.59 to 1.57) than the control groups. When only the trials reporting actual elective surgery were included in a subgroup analysis, the result remained statistically non-significant (OR 1.17; 95% CI 0.57 to 2.42).For the beta-blocker trials, when all were combined in a meta-analysis, there was a very small, non-significant protective effect for propranolol on AAA expansion (MD -0.08 mm; 95% CI -0.25 to 0.10), and non-significantly fewer patients were referred to AAA surgery in the propranolol group (OR 0.74; 95% CI 0.52 to 1.05). Bronchospasm and shortness of breath were the main adverse effects from the beta-blockers. In one trial the adverse effects were reportedly so severe that the trial was stopped early after two years.

AUTHORS' CONCLUSIONS

There is some limited evidence that antibiotic medication may have a slight protective effect in retarding the expansion rates of small AAAs. The quality of the evidence makes it unclear whether this translates into fewer referrals to AAA surgery, owing mainly to the small sample sizes of the studies.Antibiotics were generally well tolerated with minimal adverse effects. Propranolol was poorly tolerated by patients in all of the beta-blocker trials and demonstrated only minimal and non-significant protective effects. Further research on beta-blockers for AAA needs to consider the use of drugs other than propranolol.In general, there is surprisingly little high quality evidence on medical treatment for small AAAs, especially in relation to the use of newer beta-blockers, ACE inhibitors and statins.

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.

Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study

OBJECTIVE

To investigate the feasibility of endurance exercise training in patients with small abdominal aortic aneurysm (AAA), and to obtain preliminary data of its impact on important health outcomes.

DESIGN

Randomized controlled pilot study.

SETTING

University rehabilitation facility.

PARTICIPANTS

Patients with small AAA (N=28; mean age ± SD, 72±7 y).

INTERVENTION

Participants were randomized to a 12-week program of moderate-intensity endurance exercise or standard care control (encouragement to exercise only).

MAIN OUTCOME MEASURES

Safety was assessed in terms of the frequency of adverse events and changes in maximum AAA diameter. Outcomes were assessed at baseline and 12 weeks including cardiopulmonary fitness (ventilatory threshold), health-related quality of life (Medical Outcomes Study 36-Item Short-Form Health Survey [version 2]), and markers of vascular risk (eg, blood pressure and high-sensitivity C-reactive protein).

RESULTS

Of 545 patients contacted, 28 (5%) entered the trial. There were 3 (11%) dropouts. Adherence to the exercise program was 94%. There were no paradoxical increases in AAA size or adverse clinical events. Ventilatory threshold increased in the exercise group, but not the control group (adjusted mean difference, 2.5 mL·kg(-1)·min(-1); 95% confidence interval, 0.5-4.5; d=.82). Systolic blood pressure and high-sensitivity C-reactive protein decreased in the exercise group compared with the control group (d=.34 and d=.58, respectively). There were no substantial changes in anthropometric variables or quality of life.

CONCLUSIONS

Despite a low recruitment rate, the findings suggest that moderate-intensity endurance exercise training is feasible in patients with small AAA, and can evoke improvements in important health outcomes.

Nationwide trends in abdominal aortic aneurysm repair and use of endovascular repair in the emergency setting

PURPOSE

To analyze nationwide trends in abdominal aortic aneurysm (AAA) repair and the use of endovascular abdominal aortic aneurysm repair (EVAR) in the emergency setting.

MATERIALS AND METHODS

Data were obtained from the Nationwide Inpatient Sample (NIS) using the International Classification of Diseases, Ninth Revision-Clinical Modification (ICD-9-CM) codes for open and endovascular repairs from 2001-2009. Trends in outcome parameters and hospital charges were compared.

RESULTS

The number of emergency EVAR procedures increased from 382 in 2001 to 1,247 in 2009 (P < .001). During the study period, length of hospital stay associated with total number of EVAR procedures decreased from 3.8 days to 3.4 days (P < .05), and the in-hospital mortality decreased from 2.4% to 2% (P = .32). From 2001-2009, mean hospital charges associated with EVAR increased from $50,630 to $91,401 (74% increase), whereas charges associated with open repairs increased from $54,578 to $128,925 (136% increase). The proportion of patients needing rehabilitation or nursing home placement after EVAR increased from 5.8% to 7.7% (P < .01), and need for home health increased from 6.9% to 10.5% (P < .01).

CONCLUSIONS

There was a significant increase in the number of emergency EVAR procedures during the study period; however, the overall in-hospital mortality associated with EVAR remained unchanged, and the length of hospital stay showed a decreasing trend. The total hospital charges for EVAR were lower than the charges for open abdominal aneurysm repair throughout the study period; the difference in charges between the procedures showed a significant increasing trend with time.

Aortic rupture and aorto-pulmonary fistulation in the Friesian horse: characterisation of the clinical and gross post mortem findings in 24 cases

REASONS FOR PERFORMING STUDY

In horses, aortic sinus of Valsalva aneurysms or tears in the aortic root are well-recognised conditions in breeding stallions, often leading to sudden death. A more uncommon form of aortic rupture, located proximal to the ligamentum arteriosum has been reported in 3 Friesian horses.

OBJECTIVES

The purpose of this study was to phenotypically characterise aortic rupture and aorto-pulmonary fistulation in Friesian horses in terms of clinical and post mortem data based on 24 cases.

METHODS

Friesian horses that were diagnosed with aortic rupture and aorto-pulmonary fistulation over a period of 13 years (1997-2010) at the Department of Equine Sciences of Utrecht University (n = 15) and Wolvega Equine Hospital (n = 9), were included in this study. Case history, results of clinical examination and gross post mortem findings were screened and analysed.

RESULTS

Some cases were found dead without prior symptoms, but in several cases signs such as recurrent colic, peripheral oedema and sustained tachycardia were present for several weeks prior to cardiac failure. Clinical examination during hospitalisation revealed increased rectal temperature, peripheral oedema and increased jugular pulse with a bounding arterial pulse. In the majority of horses an aortic rupture of the aortic arch near the ligamentum arteriosum, concurrent with a circumferential cuff of perivascular haemorrhage and aorto-pulmonary fistulation, was found at post mortem examination.

CONCLUSIONS

Aorto-pulmonary fistulation in conjunction with aortic rupture is more common in Friesians than previously estimated. In some cases findings demonstrate a progressive pathology rather than acute cardiac failure and sudden death. An appropriate approach is necessary during post mortem examination of the heart in order not to overlook the diagnosis.

POTENTIAL RELEVANCE

Equine practitioners should realise that in Friesian horses presented with a history of recurrent false colic, coughing, sustained tachycardia and/or peripheral oedema, aortic rupture and aorto-pulmonary fistulation should be included in the differential diagnosis.

Prostaglandin receptor EP4 in abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) pathogenesis is distinguished by vessel wall inflammation. Cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase-1, key components of the most well-characterized inflammatory prostaglandin pathway, contribute to AAA development in the 28-day angiotensin II infusion model in mice. In this study, we used this model to examine the role of the prostaglandin E receptor subtype 4 (EP4) and genetic knockdown of COX-2 expression (70% to 90%) in AAA pathogenesis. The administration of the prostaglandin receptor EP4 antagonist AE3-208 (10 mg/kg per day) to apolipoprotein E (apoE)-deficient mice led to active drug plasma concentrations and reduced AAA incidence and severity compared with control apoE-deficient mice (P < 0.01), whereas COX-2 genetic knockdown/apoE-deficient mice displayed only a minor, nonsignificant decrease in incidence of AAA. EP4 receptor protein was present in human and mouse AAA, as observed by using Western blot analysis. Aortas from AE3-208-treated mice displayed evidence of a reduced inflammatory phenotype compared with controls. Atherosclerotic lesion size at the aortic root was similar between all groups. In conclusion, the prostaglandin E(2)-EP4 signaling pathway plays a role in the AAA inflammatory process. Blocking the EP4 receptor pharmacologically reduces both the incidence and severity of AAA in the angiotensin II mouse model, potentially via attenuation of cytokine/chemokine synthesis and the reduction of matrix metalloproteinase activities.

Abdominal Aortic Aneurysms

Abdominal aortic aneurysms represent both an individual risk of mortality and a socioeconomic burden for health care systems worldwide, but screening is not performed in all countries. Here, the authors summarize the pros and cons of screening to reduce abdominal aortic aneurysm–related mortality.

Statin therapy is associated with aneurysm sac regression after endovascular aortic repair

BACKGROUND

Several anatomic factors have been identified as predictive of sac behavior after endovascular aneurysm repair (EVAR). The effects of statin therapy on aneurysm sac size reduction remain controversial. This study tested the hypothesis that statin therapy enhances aneurysmal sac regression after EVAR.

METHODS

This monocentric retrospective study included patients with abdominal aortic aneurysms treated by EVAR using the Zenith (Cook, Bloomington, Ind) graft device. We excluded patients presenting with perioperative sac enlargement factors such as endoleaks, endotension, infectious, inflammatory, ruptured, or anastomotic aneurysms. We prospectively assessed standard clinical and anatomic data, as well as statin use, at the time of EVAR and during follow-up. The primary end point was the decrease in the largest transverse aortic diameter at 24 months compared with the preoperative diameter.

RESULTS

Among 166 patients treated by a Zenith device and meeting the inclusion criteria, 120 were identified as statin users and 46 as nonstatin users, with comparable characteristics. At 24 months of follow-up, statin group patients had a greater aneurysm sac reduction (25% vs 14%; P < .0001). At a threshold of 5 mm in diameter regression, statin use was a positive factor of retraction (odds ratio, 7.93; 95% confidence interval, 3.22-15.52; P < .0001). Multivariate analysis revealed statin use was an independent predictive factor of sac regression (adjusted odds ratio, 9.39; 95% confidence interval, 3.45-25.56).

CONCLUSIONS

This study showed that statin use was predictive of sac regression after EVAR with the Zenith graft device. This effect needs to be confirmed by larger randomized trials or by large population evaluation.

Imaging and management of complications of open surgical repair of abdominal aortic aneurysms

Open repair is still considered the reference standard for long-term repair of abdominal aortic aneurysms (AAA). In contrast to endovascular aneurysm repair (EVAR), patients with open surgical repair of AAA are not routinely followed up with imaging. Although complications following EVAR are widely recognized and routinely identified on follow-up imaging, complications also do occur following open surgical repair. With frequent use of multi-slice computed tomography (CT) angiography (CTA) in vascular patients, there is now improved recognition of the potential complications following open surgical repair. Many of these complications are increasingly being managed using endovascular techniques. The aim of this review is to illustrate a variety of potential complications that may occur following open surgical repair and to demonstrate their management using both surgical and endovascular techniques.

Clarithromycin suppresses the periodontal bacteria-accelerated abdominal aortic aneurysms in mice

BACKGROUND AND OBJECTIVE

Although clarithromycin (CAM) has many biological functions, including regulation of MMPs, little is known about its effect on abdominal aortic aneurysms. Periodontopathic bacteria have been reported to be associated with several kinds of circulatory diseases. The purpose of this study was therefore to clarify the effect of CAM on periodontopathic bacteria-accelerated abdominal aortic aneurysms.

MATERIAL AND METHODS

Abdominal aortic aneurysm was produced in mice by the peri-aortic application of 0.25 m CaCl(2). The mice were inoculated once per week with live Porphyromonas gingivalis, which is one of the major periodontopathic bacteria. Test mice (n=8) were given a daily oral dose of CAM, while control mice (n=13) were not.

RESULTS

Four weeks after the operation, the P. gingivalis-injected and CAM-treated mice showed a significant decrease in the aortic diameter in comparison with the mice only injected with P. gingivalis. Histopathologically, the samples obtained from the P. gingivalis-injected and CAM-treated mice showed less elastic degradation. Moreover, the plasma MMP-2 concentration of the CAM-treated mice decreased significantly.

CONCLUSION

These findings suggest that CAM administration is useful to suppress periodontal bacteria-accelerated abdominal aortic aneurysms via MMP regulation.

Long term stabilization of expanding aortic aneurysms by a short course of cyclosporine A through transforming growth factor-beta induction

Abdominal aortic aneurysms (AAAs) expand as a consequence of extracellular matrix destruction, and vascular smooth muscle cell (VSMC) depletion. Transforming growth factor (TGF)-beta 1 overexpression stabilizes expanding AAAs in rat. Cyclosporine A (CsA) promotes tissue accumulation and induces TGF -beta1 and, could thereby exert beneficial effects on AAA remodelling and expansion. In this study, we assessed whether a short administration of CsA could durably stabilize AAAs through TGF-beta induction. We showed that CsA induced TGF-beta1 and decreased MMP-9 expression dose-dependently in fragments of human AAAs in vitro, and in animal models of AAA in vivo. CsA prevented AAA formation at 14 days in the rat elastase (diameter increase: CsA: 131.9±44.2%; vehicle: 225.9±57.0%, P = 0.003) and calcium chloride mouse models (diameters: CsA: 0.72±0.14 mm; vehicle: 1.10±0.11 mm, P = .008), preserved elastic fiber network and VSMC content, and decreased inflammation. A seven day administration of CsA stabilized formed AAAs in rats seven weeks after drug withdrawal (diameter increase: CsA: 14.2±15.1%; vehicle: 45.2±13.7%, P = .017), down-regulated wall inflammation, and increased αSMA-positive cell content. Co-administration of a blocking anti-TGF-beta antibody abrogated CsA impact on inflammation, αSMA-positive cell accumulation and diameter control in expanding AAAs. Our study demonstrates that pharmacological induction of TGF-beta1 by a short course of CsA administration represents a new approach to induce aneurysm stabilization by shifting the degradation/repair balance towards healing.

Complex pathologies of angiotensin II-induced abdominal aortic aneurysms

Angiotensin II (AngII) is the primary bioactive peptide of the renin angiotensin system that plays a critical role in many cardiovascular diseases. Subcutaneous infusion of AngII into mice induces the development of abdominal aortic aneurysms (AAAs). Like human AAAs, AngII-induced AAA tissues exhibit progressive changes and considerable heterogeneity. This complex pathology provides an impediment to the quantification of aneurysmal tissue composition by biochemical and immunostaining techniques. Therefore, while the mouse model of AngII-induced AAAs provides a salutary approach to studying the mechanisms of the evolution of AAAs in humans, meaningful interpretation of mechanisms requires consideration of the heterogeneous nature of the diseased tissue.

Serpina3n attenuates granzyme B-mediated decorin cleavage and rupture in a murine model of aortic aneurysm

Granzyme B (GZMB) is a proapoptotic serine protease that is released by cytotoxic lymphocytes. However, GZMB can also be produced by other cell types and is capable of cleaving extracellular matrix (ECM) proteins. GZMB contributes to abdominal aortic aneurysm (AAA) through an extracellular, perforin-independent mechanism involving ECM cleavage. The murine serine protease inhibitor, Serpina3n (SA3N), is an extracellular inhibitor of GZMB. In the present study, administration of SA3N was assessed using a mouse Angiotensin II-induced AAA model. Mice were injected with SA3N (0–120 μg/kg) before pump implantation. A significant dose-dependent reduction in the frequency of aortic rupture and death was observed in mice that received SA3N treatment compared with controls. Reduced degradation of the proteoglycan decorin was observed while collagen density was increased in the aortas of mice receiving SA3N treatment compared with controls. In vitro studies confirmed that decorin, which regulates collagen spacing and fibrillogenesis, is cleaved by GZMB and that its cleavage can be prevented by SA3N. In conclusion, SA3N inhibits GZMB-mediated decorin degradation leading to enhanced collagen remodelling and reinforcement of the adventitia, thereby reducing the overall rate of rupture and death in a mouse model of AAA.

Heme oxygenase-1 in inflammation and cardiovascular disease

Cardiovascular disease accounts for 1 of every 2.9 deaths in the United States, thus the burden of the disease remains high. Given the high mortality and escalating healthcare cost for the disease, it is of urgent need to treat cardiovascular disease effectively. Heme oxygenase-1 (HO-1) catalyzes the oxidation of heme to generate carbon monoxide, biliverdin, and iron. These reaction products of HO-1 have potent anti-inflammatory and anti-oxidative functions. Although HO-1 is expressed at low levels in most tissues under normal basal conditions, it is highly inducible in response to various pathophysiological stresses. Numerous studies have indicated that HO-1 induction is an adaptive defense mechanism to protect cells and tissues against injury in many disease settings. This review highlights the role of HO-1 in inflammation and several cardiovascular diseases-atherosclerosis, myocardial infarction, graft survival after heart transplantation, and abdominal aortic aneurysm. Given that inflammation and oxidative stress are associated with development of cardiovascular disease and that HO-1 has anti-inflammatory and anti-oxidative properties, HO-1 is emerging as a great potential therapeutic target for treating cardiovascular disease.

Chinese red yeast rice attenuates the development of angiotensin II-induced abdominal aortic aneurysm and atherosclerosis

OBJECTIVE

Abdominal aortic aneurysm (AAA) is a chronic vascular disease characterized by medial degradation and inflammation. No medical approaches have been validated for treating AAA, and therapeutic options are limited to regular surveillance leading to surgical intervention. This study aimed to investigate whether administration of Chinese red yeast rice (Monascus purpureus; RYR) suppressed angiotensin II (AngII)-induced AAA and atherosclerosis.

METHODS AND RESULTS

Apolipoprotein E-deficient male mice fed a normal diet were administered either RYR extract (200 mg/kg/day) or vehicle by gavage for 1 week before initiating AngII infusion (1000 ng/kg/min) via subcutaneous osmotic pumps for 28 days. Red yeast rice extract administration significantly suppressed AngII-induced expansion of suprarenal diameter and area (P<.05). Furthermore, RYR extract significantly reduced atherosclerotic lesion areas in both the intima of aortic arches and cross sections of aortic roots (P<.05). These effects were associated with reductions of serum total cholesterol, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, matrix metalloproteinase (MMP) 2 and increases of serum macrophage migration inhibitory factor, but no changes in serum interleukin (IL) 1α, IL-6, monocyte chemoattractant protein 1, MMP-9 and expression of MMP-2 and MMP-9 in aortic walls.

CONCLUSIONS

This study demonstrated that RYR extract administration suppressed AngII-induced AAA and atherosclerosis associated with regulating inflammation responses independent of lipid-lowering effects. Red yeast rice may have preventive potential for patients with AAA.

Effects of exercise training in patients with abdominal aortic aneurysm: preliminary results from a randomized trial

OBJECTIVE

No effective medical therapy exists for early abdominal aortic aneurysm (AAA) disease. Lower extremity exercise improves aortic hemodynamics and reduces inflammation, but the safety and efficacy of exercise training in AAA disease is unknown. As an interim analysis of our prospective, randomized, longitudinal trial of exercise for AAA suppression, we investigated whether subjects with early disease could safely achieve target metabolic and hemodynamic goals.

METHODS

One hundred eight participants were randomized to exercise training (EX) or usual care (UC). EX subjects participated in a combination of in-house and home exercise training, with efforts directed toward moderate daily exercise participation. Comparisons were made between EX and UC subjects who completed 1 year of follow-up (n = 26 and 31, respectively, mean age 72 ± 8 years). EX and UC groups were compared for safety, cardiopulmonary exercise test responses, weekly energy expenditure, and biometric indices.

RESULTS

No paradoxical increase in AAA growth rate or adverse clinical events occurred as a consequence of exercise training. EX participants expended an average of 2269 ± 1207 kcal/wk and increased exercise capacity (42% increase in treadmill time, 24% increase in estimated metabolic equivalents, P = .01 and .08 between groups, respectively). EX participants demonstrated a significant reduction in C-reactive protein and tended to reduce waist circumference and waist-to-hip ratio (P = .06 and .07, respectively).

CONCLUSIONS

Preliminary analyses suggest that exercise training is well tolerated and sustainable in small AAA subjects over 1 year. Despite age and comorbidities, exercising AAA subjects achieve meaningful exercise targets and significantly modify activity-dependent variables.

Cost-effectiveness of intensive smoking cessation therapy among patients with small abdominal aortic aneurysms

INTRODUCTION

Smoking cessation is one of the few available strategies to decrease the risk for expansion and rupture of small abdominal aortic aneurysms (AAAs). The cost-effectiveness of an intensive smoking cessation therapy in patients with small AAAs identified at screening was evaluated.

METHODS

A Markov cohort simulation model was used to compare an 8-week smoking cessation intervention with adjuvant pharmacotherapy and annual revisits vs nonintervention among 65-year-old male smokers with a small AAA identified at screening. The smoking cessation rate was tested in one-way sensitivity analyses in the intervention group (range, 22%-57%) and in the nonintervention group (range, 3%-30%). Literature data on the effect of smoking on AAA expansion and rupture was factored into the model.

RESULTS

The intervention was cost-effective in all tested scenarios and sensitivity analyses. The smoking cessation intervention was cost-effective due to a decreased need for AAA repair and decreased rupture rate even when disregarding the positive effects of smoking cessation on long-term survival. The incremental cost/effectiveness ratio reached the willingness-to-pay threshold value of €25,000 per life-year gained when assuming an intervention cost of > €3250 or an effect of ≤ 1% difference in long-term smoking cessation between the intervention and nonintervention groups. Smoking cessation resulted in a relative risk reduction for elective AAA repair by 9% and for rupture by 38% over 10 years of follow-up.

CONCLUSIONS

An adequate smoking cessation intervention in patients with small AAAs identified at screening can cost-effectively increase long-term survival and decrease the need for AAA repair.