Proteins associated with the size and expansion rate of the abdominal aortic aneurysm wall as identified by proteomic analysis

Vitamin D as A Protector of Arterial Health: Potential Role in Peripheral Arterial Disease Formation

Atherosclerotic occlusive diseases and aneurysms that affect large and medium-sized arteries outside the cardiac and cerebral circulation are collectively known as peripheral arterial disease (PAD). With a rise in the rate of aging population worldwide, the number of people diagnosed with PAD is rapidly increasing. The micronutrient vitamin D is an important steroid hormone that acts on many crucial cellular mechanisms. Experimental studies suggest that optimal levels of vitamin D have beneficial effects on the heart and blood vessels; however, high vitamin D concentrations have been implicated in promoting vascular calcification and arterial stiffness. Observations from various clinical studies shows that deficiency of vitamin D has been associated with a greater risk of PAD. Epidemiological studies have often reported an inverse relation between circulating vitamin D status measured in terms of 25-hydroxivitamin D [25(OH)D] levels and increased cardiovascular disease risk; however, randomized controlled trials did not show a consistent positive effect of vitamin D supplementation on cardiovascular disease risk or events. Even though PAD shares all the major risk factors with cardiovascular diseases, the effect of vitamin D deficiency in PAD is not clear. Current evidence suggests a strong role of vitamin D in promoting genomic and epigenomic changes. This review summarises the current literature that supports the notion that vitamin D deficiency may promote PAD formation. A better understanding of underlying pathological mechanisms will open up new therapeutic possibilities which is the main unmet need in PAD management. Furthermore, epigenetic evidence shows that a more holistic approach towards PAD prevention that incorporates a healthy lifestyle, adequate exercise and optimal nutrition may be more effective in protecting the genome and maintaining a healthy vasculature.

Abdominal Aortic Aneurysms Growth Is Associated With High Concentrations of Plasma Proteins in the Intraluminal Thrombus and Diseased Arterial Tissue

Objective—

Porosity of the intraluminal thrombus (ILT) is believed to convey biologically active components from the bloodstream toward the aneurismal wall. Accumulation of molecules in the abdominal aortic aneurysmatic tissue may influence vascular protein turnover and regulate abdominal aortic aneurysm growth. We sought to identify proteins with concentrations in the ILT and the abdominal aortic aneurysm wall which associate with aneurysmal expansion rate.

Approach and Results—

Proteomic analysis by liquid chromatography tandem-mass spectrometry of separated wall and ILT samples was correlated with preoperative aneurysmal growth rate in 24 individuals operated electively for infrarenal abdominal aortic aneurysm. The median preoperative growth rate was 3.8 mm/y (interquartile range, 3) and the mean observational time was 3.3±1.7 years. Plasma components dominated the group of proteins with tissue concentrations, which correlate positively with growth rates ( P <0.001, Fisher exact test, both in the ILT and the wall). In contrast, in the wall and thrombus samples, ECM (extracellular matrix) proteins were significantly more prevalent in the group of proteins with negative correlations to growth rates ( P <0.05, Fisher exact test). Similarly, a long series of proteins, related to cellular functions correlated negatively to growth rates.

Conclusions—

When the preoperative aneurysmatic growth rate has been high, the concentration of many plasma proteins residing in the ILT and the aneurysmatic tissue is also high, compatible with the hypothesis of increased tissue porosity and accumulation of plasma components as a driver of aneurysm expansion. Moreover, many matrix and cellular proteins which are found in high concentrations in slower-growing aneurysms provides new knowledge about potential treatment targets.

Preliminary analysis of proteome alterations in non-aneurysmal, internal mammary artery tissue from patients with abdominal aortic aneurysms

Objective

The pathogenesis of abdominal aortic aneurysms (AAA) involves a disturbed balance of breakdown and buildup of arterial proteins. We envision that individuals with AAA carry generalized arterial protein alterations either because of effects of genetically or environmental AAA risk factors or because of compensatory changes due to signaling molecules released from the affected aneurysmal tissue.

Approach

Protein extraction and quantitative proteome analysis by LC-MS/MS (liquid chromatography-mass spectrometry) was done on individual samples from the internal mammary artery from 11 individuals with AAA and 33 sex- and age-matched controls without AAA. Samples were selected from a biobank of leftover internal mammary arterial tissue gathered at coronary by-pass operations.

Results

We identified and quantitated 877 proteins, of which 44 were differentially expressed between the two groups (nominal p-values without correction for multiple testing). Some proteins related to the extracellular matrix displayed altered concentrations in the AAA group, particularly among elastin-related molecules [elastin, microfibrillar-associated protein 4 (MFAP4), lysyl oxidase]. In addition, several histones e.g. (e.g. HIST1H1E, HIST1H2BB) and other vascular cell proteins (e.g. versican, type VI collagen) were altered.

Conclusions

Our results support the notion that generalized alterations occur in the arterial tree in patients with AAA. Elastin-related proteins and histones seem to be part of such changes, however these preliminary results require replication in an independent set of specimens and validation by functional studies.

Proteomic analysis in cardiovascular research

Advances in mass spectrometry technology and bioinformatics using clinical human samples have expanded quantitative proteomics in cardiovascular research. There are two major proteomic strategies: namely, "gel-based" or "gel-free" proteomics coupled with either "top-down" or "bottom-up" mass spectrometry. Both are introduced into the proteomic analysis using plasma or serum sample targeting 'biomarker" searches of aortic aneurysm and tissue samples, such as from the aneurysmal wall, calcific aortic valve, or myocardial tissue, investigating pathophysiological protein interactions and post-translational modifications. We summarize the proteomic studies that analyzed human samples taken during cardiovascular surgery to investigate disease processes, in order to better understand the system-wide changes behind known molecular factors and specific signaling pathways.

Redox proteomic analysis of serum from aortic anerurysm patients: insights on oxidation of specific protein target

Oxidative stress is undoubtedly one of the main players in abdominal aortic aneurysm (AAA) pathophysiology.

Transition from identity to bioactivity-guided proteomics for biomarker discovery with focus on the PF2D platform

Proteomic strategies provide a valuable tool kit to identify proteins involved in diseases. With recent progress in MS technology, high throughput proteomics has accelerated protein identification for potential biomarkers. Numerous biomarker candidates have been identified in several diseases, and many are common among pathologies. An overall strategy that could complement and strengthen the search for biomarkers is combining protein identity with biological outcomes. This review describes an emerging framework of bridging bioactivity to protein identity, exploring the possibility that some biomarkers will have a mechanistic role in the disease process. A review of pulmonary, cardiovascular, and CNS biomarkers will be discussed to demonstrate the utility of combining bioactivity with identification as a means to not only find meaningful biomarkers, but also to uncover functional mediators of disease.

Recent advances in proteomic technologies applied to cardiovascular disease

In recent years, the diagnosis of cardiovascular disease (CVD) has increased its potential, also thanks to mass spectrometry (MS) proteomics. Modern MS proteomics tools permit analyzing a variety of biological samples, ranging from single cells to tissues and body fluids, like plasma and urine. This approach enhances the search for informative biomarkers in biological samples from apparently healthy individuals or patients, thus allowing an earlier and more precise diagnosis and a deeper comprehension of pathogenesis, development and outcome of CVD to further reduce the enormous burden of this disease on public health. In fact, many differences in protein expression between CVD-affected and healthy subjects have been detected, but only a few of them have been useful to establish clinical biomarkers because they did not pass the verification and validation tests. For a concrete clinical support of MS proteomics to CVD, it is, therefore, necessary to: ameliorate the resolution, sensitivity, specificity, throughput, precision, and accuracy of MS platform components; standardize procedures for sample collection, preparation, and analysis; lower the costs of the analyses; reduce the time of biomarker verification and validation. At the same time, it will be fundamental, for the future perspectives of proteomics in clinical trials, to define the normal protein maps and the global patterns of normal protein levels, as well as those specific for the different expressions of CVD.

Proteomic analysis of the abdominal aortic aneurysm wall

PURPOSES

A ruptured AAA (rAAA) is a common cause of death in males over 60 years of age, and the global mortality from rAAA exceeds 80 %. The pathological processes occurring in the wall of the developing AAA are still unclear. The potential pathophysiological mechanisms underlying aortic aneurysms have been examined by many studies using immunohistochemistry and were, therefore, targeted at specific, preselected protein antigens.

METHODS

We collected samples of tissue from anterior wall of an aneurysm sac from 15 patients indicated for AAA resection (group A) during the period from 2010 to 2011. These samples were subjected to a proteomic analysis. In addition, we collected control samples of identical aortic tissue from 10 heart-beating deceased organ donors (group B).

RESULTS

A total of 417 differentially expressed protein fractions were identified, 18 of which were only detected in the healthy controls, while 85 were specific for aneurysm tissue and 314 were detectable in both groups. In 175 protein fractions, the gel-derived spot volumes differed significantly between aneurismal and healthy aortic tissue.

CONCLUSIONS

We found a significant difference in the proteome of the AAA tissue and non-dilated aortic tissue. We demonstrated that the AAA proteome is considerably richer and more varied than the healthy and atherosclerotic aorta. We believe that our results clearly demonstrate a completely different etiopathogenesis of atherosclerosis and aneurismal disease.

Balanced mineralization in the arterial system: possible role of osteoclastogenesis/osteoblastogenesis in abdominal aortic aneurysm and stenotic disease

Arterial calcification is the result of the same highly organized processes as seen in bone, which rely on a delicate balance between osteoblasts and osteoclasts. Although previously understood as passive precipitation, evidence has accumulated to suggest that arterial calcification is the result of organized, regulated processes bearing many similarities to osteogenesis in bone, including the presence of subpopulations of arterial wall cells that retain osteoblastic lineage potential. These cells have the potential to form mineralized nodules and express osteoblast markers, including bone morphogenetic protein-2, osteocalcin, osteopontin, and alkaline phosphatase. By contrast, osteoclast-like cells mediate the catabolic process of mineral resorption. Recent data shows that cells positive for tartrate-resistant acid phosphatase, a major marker for osteoclasts, have been histologically identified in atherosclerotic lesions and are referred to as osteoclast-like cells. Evidence has accumulated to suggest that initial arterial calcification through passive precipitation of calcium phosphate initiates balanced mineralization regulated by osteoclast-like and osteoblast-like cells. Subsequently, various pathogenic conditions may trigger an imbalance between osteoblastogenesis and osteoclastogenesis, leading to either calcification in stenotic/occlusive disease or destruction of the extracellular matrix in aneurysmal disease. Further elucidation of these newly emerging concepts could lead to a novel therapeutic approach to arterial stenotic/occlusive disease and/or abdominal aortic aneurysm.

Hérnias incisionais no pós-operatório de correção de aneurisma de aorta abdominal

CONTEXTO: A incidência de hérnia incisional no pós-operatório da correção aberta de aneurisma de aorta abdominal é alta, variando de 10 a 37% e mais de três vezes mais comum do que em pacientes submetidos à correção para doença obstrutiva aorto-ilíaca. OBJETIVO: Apresentar a incidência de hérnia incisional em um grupo de pacientes acompanhados no pós-operatório da correção aberta de aneurisma de aorta abdominal. MÉTODOS: Série de casos em uma população de 144 pacientes operados por aneurisma de aorta abdominal, entre junho de 1989 e junho de 2010, e que estão em acompanhamento regular no Ambulatório de Moléstias Vasculares. RESULTADOS: O seguimento médio dos pacientes foi de 63 meses (1 a 238). A idade média foi de 67 anos (45 a 91) e o tamanho médio dos aneurismas foi de 6,54 cm. Foram realizadas 130 laparotomias medianas xifo-púbicas e 13 acessos extraperitoniais pelo flanco esquerdo. Nestes pacientes, a incidência de hérnia incisional foi de 18,5 e 7,7%, respectivamente, para incisões na linha média ou no flanco (p=0,315). Um paciente apresentou abaulamento da musculatura oblíqua por denervação. Foi realizada uma laparotomia transversa, que não apresentou hérnia no pós-operatório tardio. CONCLUSÕES: A incidência de hérnia incisional na cirurgia aberta para correção de aneurisma de aorta abdominal é alta, ocorre com maior frequência em incisões da linha média e tem relação direta com a técnica empregada para o fechamento da aponeurose, exigindo do cirurgião atenção especial para este tempo cirúrgico para evitar a causa mais comum de reoperação em tal grupo de pacientes.

Differential protein expression in serum of abdominal aortic aneurysm patients - a proteomic approach

OBJECTIVE

The aim of the study is to investigate the differential expression of proteins in serum of abdominal aortic aneurysm (AAA) patients in relation to aneurysm size (D(max)) and progression.

METHODS

Two-dimensional differential in-gel electrophoresis (2D-DIGE) together with tandem mass spectrometry (MS/MS) was used to analyse the serum proteome from patients with small (D(max) 30-54 mm) AAA, either stable (increase D(max) <5 mm year⁻¹; n = 8) or progressive (increase D(max) ≥5 mm year⁻¹; n = 8), and large (D(max) ≥ 55 mm; n = 8) AAA. The identified proteins were quantitatively validated in a larger population (n = 80).

RESULTS

Several proteins were differentially expressed in serum of small stable, small progressive and large AAA. Three validated proteins (immunoglobulin G (IgG), α1-antitrypsin (α1-AT) and Factor XII activity) showed strong correlation with D(max). Size combined with either Factor XII activity or α1-antitrypsin had minimal effect on the prognostic value in predicting aneurysm progression compared with size alone (area under the curve (AUC), 0.85; 95% confidence interval (CI), 0.73-0.97; p < 0.001 and AUC, 0.85; 95% CI, 0.72-0.98; p < 0.001 vs. AUC, 0.83; 95% CI, 0.71-0.96; p < 0.001, respectively).

CONCLUSION

The present study indicates that both Factor XII and α1-antitrypsin are found in increased amounts in the serum of patients with expanding AAA. However, combination of either Factor XII or α1-antitrypsin with aneurysm diameter had little effect on prediction of aneurysm progression versus diameter alone.