Histopathological Characterization of Abdominal Aortic Aneurysms from Patients with Multiple Aneurysms Compared to Patients with a Single Abdominal Aortic Aneurysm.

The aim of this study was to investigate histopathological differences in abdominal aortic aneurysms (AAAs) between patients with multiple and single arterial aneurysms, as we suspect that there are different underlying mechanisms in aneurysm formation. Analysis was based on a previous retrospective study on patients with multiple arterial aneurysms (mult-AA; defined as at least four, n = 143) and a single AAA (sing-AAA, n = 972) who were admitted to our hospital for treatment between 2006 and 2016. Available paraffin-embedded AAA wall specimens were derived from the Vascular Biomaterial Bank Heidelberg (mult-AA, n = 12 vs. sing-AAA, n = 19). Sections were analyzed regarding structural damage of the fibrous connective tissue and inflammatory cell infiltration. Alterations to the collagen and elastin constitution were assessed by Masson-Goldner trichrome and Elastica van Gieson staining. Inflammatory cell infiltration, response and transformation were assessed by CD45 and IL-1ß immunohistochemistry and von Kossa staining. The extent of aneurysmal wall alterations was assessed by semiquantitative gradings and was compared between the groups using Fisher's exact test. IL-1ß was significantly more present in the tunica media in mult-AA compared to sing-AAA (p = 0.022). The increased expression of IL-1ß in mult-AA compared to sing-AAA indicates inflammatory processes play a role in aneurysm formation in patients with multiple arterial aneurysms.

Mitochondrial Dysfunction and Increased DNA Damage in Vascular Smooth Muscle Cells of Abdominal Aortic Aneurysm (AAA-SMC).

There is increasing evidence for enhanced oxidative stress in the vascular wall of abdominal aortic aneurysms (AAA). Mitochondrial damage and dysfunction are hypothesized to be actors in altered production of reactive oxygen species (ROS) and oxidative stress. However, the role of mitochondria and oxidative stress in vascular remodelling and progression of AAA remains uncertain. We here addressed whether mitochondrial dysfunction is persistently increased in vascular smooth muscle cells (VSMCs) isolated from AAA compared to healthy VSMC. AAA-derived VSMC cultures (AAA-SMC, n = 10) and normal VSMC cultures derived from healthy donors (n = 7) were grown in vitro and analysed for four parameters, indicating mitochondrial dysfunction: (i) mitochondrial content and morphology, (ii) ROS production and antioxidative response, (iii) NADP+/NADPH content and ratio, and (iv) DNA damage, in the presence or absence of angiotensin II (AngII). AAA-SMC displayed increased mitochondrial circularity (rounded shape), reduced mitochondrial area, and reduced perimeter, indicating increased fragmentation and dysfunction compared to healthy controls. This was accompanied by significantly increased O2 - production, reduced NADP+/NADPH levels, a lower antioxidative response (indicated by antioxidative response element- (ARE-) driven luciferase reporter assays), more DNA damage (determined by percentage of γ-H2A.X-positive nuclei), and earlier growth arrest in AAA-SMC. Our data suggest that mitochondrial dysfunction and oxidative stress are persistently increased in AAA-SMC, emphasizing their implication in the pathophysiology of AAA.

Characteristics of patients with multiple arterial aneurysms.

Background: The aim of this retrospective cross-sectional observational study was to determine differences of patients with multiple arterial aneurysms to patients with single arterial aneurysms. Patients and methods: Patients with the diagnosis of an arterial aneurysm from January 2006 to January 2016 in the department of vascular surgery Heidelberg were investigated. Excluded were patients with hereditary disorders of connective tissue or systemic inflammatory disease, as well as other arterial pathologies than true aneurysms. Patients with multiple aneurysms (defined by at least four aneurysms) were compared to patients with single aneurysms concerning age at initial diagnosis, sex and affected arterial site. To verify the findings, a replication of the study was performed at a comparable institution. Results: Of 3107 patients with arterial aneurysms, 918 were excluded. Of the resulting 2189 patients, 1238 (56.6%) patients had a single, 808 (36.9%) two or three, and 143 (6.5%) at least four aneurysms (group mult-AA). Nine hundred seventy-two patients (44.4%) had a single abdominal aortic aneurysm (group sing-AAA). Age at initial diagnosis differed between mult-AA (66.7±9.5 y) and sing-AAA (69.1±8.6 y) (p=0.0338). Within mult-AA, 138 patients (96.5%) were male, compared with 865 patients (89.0%) in sing-AAA (p=0.0041). The most frequent aneurysm localization shifted from the abdominal aorta and its branches in patients with a single aneurysm (n=1029; 83.1%) to pelvic and leg arteries in patients with at least four aneurysms (n=318; 63.2%). The replication of the study at the department of vascular surgery Frankfurt confirmed the younger age at initial diagnosis in mult-AA (67.3±12.5 y) compared to sing-AAA (70.9±9.6 y) (p=0.0259) and the distribution shift toward the arteries below the aortic bifurcation in mult-AA. Conclusions: Patients with multiple aneurysms are younger at initial diagnosis and differ concerning aneurysm localization compared to patients with a single aneurysm.

Gene Expression Profiling in Abdominal Aortic Aneurysms.

Gene expression profiling of abdominal aortic aneurysms (AAA) indicates that chronic inflammatory responses, active matrix metalloproteinases, and degradation of the extracellular matrix components are involved in disease development and progression. This study investigates intra- and interpersonal RNA genome-wide expression profiling differences (Illumina HumanHT-12, BeadCHIP expression) of 24 AAA biopsies from 12 patients using a single gene and pathway (GeneOntology, GO enrichment) analysis. Biopsies were collected during open surgical AAA repair and according to prior finite element analysis (FEA) from regions with the highest and lowest wall stress. Single gene analysis revealed a strong heterogeneity of RNA expression parameters within the same and different AAA biopsies. The pathway analysis of all samples showed significant enrichment of genes from three different signaling pathways (integrin signaling pathway: fold change FC 1.63, p = 0.001; cholecystokinin receptor pathway: FC 1.60, p = 0.011; inflammation mediated by chemokine signaling pathway: FC 1.45, p = 0.028). These results indicate heterogeneous gene expression patterns within the AAA vascular wall. Single biopsy investigations do not permit a comprehensive characterization of activated molecular processes in AAA disease.

Multiple Arterial Dissections and Connective Tissue Abnormalities.

BACKGROUND: Although patients with multiple arterial dissections in distinct arterial regions rarely present with known connective tissue syndromes, we hypothesized that mild connective tissue abnormalities are common findings in these patients. METHODS: From a consecutive register of 322 patients with cervical artery dissection (CeAD), we identified and analyzed 4 patients with a history of additional dissections in other vascular beds. In three patients, dermal connective tissue was examined by electron microscopy. DNA from all four patients was studied by whole-exome sequencing and copy number variation (CNV) analysis. RESULTS: The collagen fibers of dermal biopsies were pathologic in all three analyzed patients. One patient carried a CNV disrupting the COL3A1 and COL5A2 genes (vascular or hypermobility type of Ehlers-Danlos syndrome), and another patient a CNV in MYH11 (familial thoracic aortic aneurysms and dissections). The third patient carried a missense substitution in COL5A2. CONCLUSION: Three patients showed morphologic alterations of the dermal connective tissue, and two patients carried pathogenic variants in genes associated with arterial connective tissue dysfunction. The findings suggest that genetic testing should be recommended after recurrent arterial dissections, independently of apparent phenotypical signs of connective tissue disorders.

Inflammasomes in the Pathophysiology of Aortic Disease.

Aortic diseases comprise aneurysms, dissections, and several other pathologies. In general, aging is associated with a slow but progressive dilation of the aorta, along with increased stiffness and pulse pressure. The progression of aortic disease is characterized by subclinical development or acute presentation. Recent evidence suggests that inflammation participates causally in different clinical manifestations of aortic diseases. As of yet, diagnostic imaging and surveillance is mainly based on ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). Little medical therapy is available so far to prevent or treat the majority of aortic diseases. Endovascular therapy by the introduction of covered stentgrafts provides the main treatment option, although open surgery and implantation of synthetic grafts remain necessary in many situations. Because of the risks associated with surgery, there is a need for identification of pharmaceutical targets interfering with the pathophysiology of aortic remodeling. The participation of innate immunity and inflammasome activation in different cell types is common in aortic diseases. This review will thus focus on inflammasome activities in vascular cells of different chronic and acute aortic diseases and discuss their role in development and progression. We will also identify research gaps and suggest promising therapeutic targets, which may be used for future medical interventions.

The C57Bl/6J mouse strain is more susceptible to angiotensin II-induced aortic aneurysm formation than C57Bl/6N.

BACKGROUND AND AIMS: Genetic variations between C57Bl/6 mouse substrains are highly relevant to the investigation of cardiovascular disease. We here assessed whether these variations have an impact on the incidence of abdominal aortic aneurysms (AAA) in C57Bl/6J and 6 N mice. METHODS: AAA were induced by subcutaneous infusion of 1500 ng/kg*min Angiotensin-II for four weeks in six-month-old male CB57Bl/6J and 6N mice. Aortic smooth muscle cells (VSMC) were isolated from untreated animals for in vitro analysis. RESULTS: C57Bl/6J mice are more susceptible to AAA formation (76.5% vs. 7.1%, p = 0.0002). C57Bl/6J VSMC expressed more pro-inflammatory molecules such as Nlrp3, Aim2 and NF-κB. Additionally, these cells presented significantly higher levels of NADP/NADPH and oxidative DNA modifications, as indicated by 8-OHdG-staining, compared to C57Bl/6N VSMC. CONCLUSIONS: In contrast to previous reports, we present evidence that six-month-old C57BL/6J, but not C57BL/6N mice develop AAA. In accordance with the deficiency of nicotinamide-nucleotide-transhydrogenase (Nnt), C57BL/6J VSMC displayed increased oxidative stress, oxidative DNA damage and a stronger inflammatory phenotype than C57BL/6N VSMC.

Inflammasome Targeted Therapy as Novel Treatment Option for Aortic Aneurysms and Dissections: A Systematic Review of the Preclinical Evidence.

Both aortic aneurysm and dissection are life threatening pathologies. In the lack of a conservative medical treatment, the only therapy consists of modifying cardiovascular risk factors and either surgical or endovascular treatment. Like many other cardiovascular diseases, in particular atherosclerosis, aortic aneurysm and dissection have a strong inflammatory phenotype. Inflammasomes are part of the innate immune system. Upon stimulation they form multi protein complexes resulting mainly in activation of interleukin-1ß and other cytokines. Considering the gathering evidence, that inflammasomes are decisively involved in the emergence and progression of aortic diseases, inflammasome targeted therapy provides a promising new treatment approach. A systematic review following the PRISMA guidelines on the current preclinical data regarding the potential role of inflammasome targeted drug therapy as novel treatment option for aortic aneurysms and dissections was performed. Included were all rodent models of aortic disease (aortic aneurysm and dissection) evaluating a drug therapy with direct or indirect inhibition of inflammasomes and a suitable control group with the use of the same aortic model without the inflammasome targeted therapy. Primary and secondary outcomes were incidence of aortic disease, aortic rupture, aortic related death, and the maximum aortic diameter. The literature search of MEDLINE (via PubMed), the Web of Science, EMBASE and the Cochrane Central Registry of Registered Trials (CENTRAL) resulted in 8,137 hits. Of these, four studies met the inclusion criteria and were therefore eligible for data analysis. In all of them, targeting of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome effectively reduced the incidence of aortic disease and aortic rupture, and additionally reduced destruction of the aortic wall. Treatment strategies aiming at other inflammasomes could not be identified. In conclusion, inflammasome targeted therapies, more precisely targeting the NLRP3 inflammasome, have shown promising results in rodent models and deserve further investigation in preclinical research to potentially translate them into clinical research for the treatment of human patients with aortic disease. Regarding other inflammasomes, more preclinical research is needed to investigate their role in the pathophysiology of aortic disease. Protocol Registration: PROSPERO 2021 CRD42021279893, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021279893.

Deficiency in Aim2 affects viability and calcification of vascular smooth muscle cells from murine aortas and angiotensin-II induced aortic aneurysms.

BACKGROUND: Phenotypic transformation of vascular smooth muscle cells is a key element in vascular remodeling and aortic aneurysm growth. Previously, deletion of several inflammasome components decreased formation of aortic aneurysm (AA) in the Angiotensin II (AngII) -induced mouse model. We hypothesized that the inflammasome sensor Absent in melanoma 2 (Aim2) might affect the phenotype of vascular smooth muscle cells (VSMC), thereby reducing AA formation. METHODS: Aim2-/- mice and wild-type (WT) C57Bl/6 J mice were used as an animal model. VSMC were isolated from 6 months old mice and grown in vitro. Young (passage 3-5) and senescent (passage 7-12) cells were analyzed in vitro for calcification in mineralization medium by Alizarin Red S staining. Expression of calcification and inflammatory markers were studied by real-time RT-PCR and Western blotting, release of cytokines was determined by ELISA. To induce AA, osmotic mini-pumps loaded with AngII (1500 ng/kg bodyweight/min) were implanted for 28 days in male mice at 6 months of age. RESULTS: Compared with VSMC from WT mice, VSMC isolated from Aim2-/- mice were larger, less viable, and underwent stronger calcification in mineralization medium, along with induction of Bmp4 and repression of Tnfsf11/Rankl gene expression. In addition, Aim2 deficiency was associated with reduced inflammasome gene expression and release of Interleukin-6. Using the mouse model of AngII induced AA, Aim2 deficiency reduced AA incidence to 48.4% (15/31) in Aim2-/- mice versus 76.5% (13/17) in WT mice. In contrast to Aim2-/- mice, AA from WT mice expressed significantly increased levels of alpha-smooth muscle actin/Acta2, indicating tissue remodeling. Reduced cell proliferation in Aim2-/- mice was indicated by significantly increased p16ink4a/Cdkn2a expression in untreated and AngII-infused aortas, and by significantly lower amounts of proliferating (Ki67 positive) VSMC in AngII-infused Aim2-/- mice. CONCLUSIONS: Our results suggest a role for Aim2 in regulating VSMC proliferation and transition to an osteoblast-like or osteoclast-like phenotype, thereby modulating the response of VSMC in aortic remodeling and AA formation.

Inflammasome activity in leucocytes decreases with abdominal aortic aneurysm progression.

Abdominal aortic aneurysms (AAAs) are characterized by chronic inflammatory cell infiltration. The present extended immunohistochemistry study aimed to characterize inflammation in AAA and aortic control samples. In specific, the composition of the infiltrating immune cells and the expression of five inflammasome components in these immune cells were evaluated, in order to characterize their role in AAA development. A total of 104 biopsies from 48 AAA patients and 40 healthy specimens from organ donors were evaluated for their grade of inflammation. Infiltrating leukocytes were characterized by specific markers (CD3, CD20 and CD68), intramural localization and inflammasome protein expression [NLR family pyrin domain containing 3 (NLRP3), absent in melanoma 2 (AIM2), apoptosis­associated speck­like protein containing a caspase recruitment domain (ASC), Caspase­1 and Caspase­5]. Macrophages, B and T lymphocytes were detected to a similar extent in grade 1, 2 and 3 AAA specimens, whereas in control samples, B and T lymphocytes were rarely observed in grade 1 lesions. Expression frequencies of NLRP3, AIM2 and Caspase­5 were significantly higher in grade 1 lesions of AAA samples compared with grade 1 lesions in control samples. Finally, AIM2, ASC, and Caspase­5 displayed significantly lower expression frequencies in grade 3 compared with grade 2 AAA specimens, and all inflammasome components were less frequently detected in grade 3 than in grade 1 lesions of AAA. This indicates that inflammasome activities decrease with AAA progression in infiltrating leukocytes. No statistically significant association was found for grade 2 and grade 3 lesions and total leukocyte count, C­reactive protein levels, maximal aortic diameter, plasma cholesterol level or biomechanical parameters (derived from finite element analysis) of the respective patients. Overall, the aortic wall of AAA contained lymphocytes and macrophages with different states of activity. The present data suggested that therapeutic inhibition of specific inflammasome components might counteract AAA development and progression.

AIM2 levels and DNA-triggered inflammasome response are increased in peripheral leukocytes of patients with abdominal aortic aneurysm.

OBJECTIVE AND DESIGN: Abdominal aortic aneurysm (AAA) is heavily infiltrated with leukocytes, expressing the DNA sensor absent in melanoma 2 (AIM2) and other inflammasome components. METHODS: Using multicolour flow cytometry, we here compared the expression of the inflammasome components AIM2, NLRP3, and ASC in different peripheral immune cells derived from AAA patients with those from non-AAA patients in a case-control study. In parallel, peripheral blood mononuclear cells (PBMC) of AAA patients and controls were stimulated in vitro with poly-dA:dT or lipopolysaccharide (LPS) to analyze inflammasome activation. RESULTS: AIM2 expression was significantly increased in peripheral granulocytes (P = 0.026), monocytes (P = 0.007), B lymphocytes (P < 0.0001), and T lymphocytes (P = 0.004) of AAA patients. Expression of other inflammasome components did not differ between the groups. Following in vitro stimulation with foreign DNA, PBMC derived from AAA patients released significantly more IL-1ß (P = 0.022) into the supernatant than PBMC from control patients. In contrast, IL-1ß release upon LPS stimulation did not differ between the PBMC groups. CONCLUSION: The data indicate the increased activation of an AIM2 inflammasome in peripheral immune cells of AAA patients and point to a systemic AIM2-associated immune response to AAA.

Necrotic cell debris induces a NF-κB-driven inflammasome response in vascular smooth muscle cells derived from abdominal aortic aneurysms (AAA-SMC).

Abdominal aortic aneurysm (AAA) is a multi-factorial progressive vascular disease with life-threatening complications. Increasing evidence suggests that smooth muscle cell (SMC) dysfunction and cell death contribute to dilatation and rupture of the aorta by inducing an inflammatory response. The exact mechanism of this response however, is incompletely understood. We here investigated in vitro the capacity of autologous necrotic cell debris (CD) to induce inflammasome components and inflammatory mediators in aortic SMC (AAA-SMC) isolated from patients with AAA undergoing surgical repair. AAA-SMCs were additionally primed with Interferon- γ (IFN-γ) before treatment with CD in order to mimic the proinflammatory status caused by higher IFN-γ concentrations that have been demonstrated in the wall of AAAs. Real-time RT-PCR revealed that CD significantly increased NLRP3 and IL1B mRNA expression in different SMC cultures within 6 h of exposure. Priming of the AAA-SMC with IFN-γ significantly increased expression of NLRP3, AIM2, IFI16 and CASP1 mRNAs, whereas IL1B mRNA was reduced. Additional exposure of IFN-γ-primed AAA-SMC to CD for 6-24 h, further augmented expression of AIM2, NLRP3, and Caspase-1 protein levels. Analysis of the SMC supernatants by ELISA revealed CD-induced release of the senescence-associated cytokines IL-6 and MCP-1 in native and IFN-γ-primed SMC, whereas no secretion of Interleukin-(IL) 1α and IL-1ß secretion were observed. Our results implicate a role of necrotic cell debris derived from dead neighboring cells in SMC dysfunction and in inflammatory response of AAA tissue.

Gene Expression Profiling in Abdominal Aortic Aneurysms After Finite Element Rupture Risk Assessment.

PURPOSE: To investigate the association between local biomechanical rupture risk calculations from finite element analysis (FEA) and whole-genome profiling of the abdominal aortic aneurysm (AAA) wall to determine if AAA wall regions with highest and lowest estimated rupture risk show different gene expression patterns. METHODS: Six patients (mean age 74 years; all men) scheduled for open surgery to treat asymptomatic AAAs (mean diameter 55.2±3.5 mm) were recruited for the study. Rupture risk profiles were estimated by FEA from preoperative computed tomography angiography data. During surgery, AAA wall samples of ~10 mm2 were extracted from the lowest and highest rupture risk locations identified by the FEA. Twelve samples were processed for RNA extraction and subsequent whole genome expression profiling. Expression of single genes and of predefined gene groups were compared between vessel wall areas with highest and lowest predicted rupture risk. RESULTS: Normalized datasets comprised 15,079 gene transcripts with expression above background. In biopsies with high rupture risk, upregulation of 18 and downregulation of 18 genes was detected when compared to the low-risk counterpart. Global analysis of predefined gene groups revealed expression differences in genes associated with extracellular matrix (ECM) degradation (p<0.001), matrix metalloproteinase activity (p<0.001), and chemokine signaling (p<0.001). CONCLUSION: Increased expression of genes involved in degrading ECM components was present in AAA wall regions with highest biomechanical stress, supporting the thesis of mechanotransduction. More experimental studies with cooperation of multicenter vascular biobanks are necessary to understand AAA etiologies and identify further parameters of FEA model complementation.

Reduced glyoxalase 1 activity in carotid artery plaques of nondiabetic patients with increased hemoglobin A1c level.

OBJECTIVE: Glyoxalase 1 (GLO1) is ubiquitously expressed in the cytosol of the cell and is the major opponent against the reactive metabolite methylglyoxal, which is involved in the development of atherosclerosis. Nondiabetic individuals with an increased hemoglobin A1c (HbA1c) level are at higher risk for development of cardiovascular diseases. As such, this study investigated whether there was an association between reduced GLO1 activity in atherosclerotic lesions of nondiabetic patients with an increased HbA1c level. METHODS: HbA1c level was determined in venous blood of patients with carotid artery disease. Protein level of GLO1 was measured in endarterectomy-derived carotid artery plaques by Western blotting. Activity was measured by spectrophotometric assay in the plaques as well as in the erythrocytes; GLO1 activity in erythrocytes was compared with that in a cohort of healthy individuals (n = 15; 33% men; average age, 60 years). RESULTS: There were 36 patients with carotid artery disease (69% men; average age, 69 years) included in this study and divided into two equal groups: group I, HbA1c < 5.7% (<39 mmol/mol); and group II, 5.7% ≤ HbA1c < 6.5% (39 mmol/mol ≤ HbA1c < 48 mmol/mol). GLO1 activity in carotid plaques was reduced by 29% in group II compared with group I (P = .048), whereas protein expression was unchanged (P = .25). Analysis of GLO1 activity in erythrocytes revealed no difference between the groups (P = .36) or in comparison to healthy controls (P = .15). Examination of clinical parameters showed an increased amount of patients with concomitant peripheral arterial disease in group II (44% vs 10%; P = .020). CONCLUSIONS: Reduction of GLO1 activity in atherosclerotic lesions of nondiabetic patients with increased HbA1c is associated with a functional involvement of this protective enzyme in atherogenesis. Systemic GLO1 activity seems to be independent of both HbA1c and localized atherosclerosis as it was unchanged between group I and group II as well as compared with healthy controls, respectively.

Sex- and disease-specific inflammasome signatures in circulating blood leukocytes of patients with abdominal aortic aneurysm.

Male sex is a risk factor for abdominal aortic aneurysm (AAA). Within the AAA adventitia, infiltrating leukocytes express high levels of inflammasome components. To further elucidate the role of inflammatory cells in the pathogenesis of AAA, we here addressed expression and functionality of inflammasome components in peripheral blood mononuclear cells (PBMC) of AAA patients in association with sex. PBMC and plasma were isolated from 100 vascular patients, including 34 pairs of AAA patients and age/sex-matched non-AAA patients. Male PBMC were found to express significantly higher mRNA levels of AIM2, NLRP3, ASC (PYCARD), CASP1, CASP5, and IL1B (all P < 0.0001) than female PBMC. Within the male patients, PBMC of AAA patients displayed increased mRNA levels of NLRP3 (P = 0.044), CASP1 (P = 0.032) and IL1B (P = 0.0004) compared to matched non-AAA PBMC, whereas there was no difference between female AAA and non-AAA patients. The relative protein level of NLRP3 was significantly lower in PBMC lysates from all AAA patients than in matched controls (P = 0.038), whereas AIM2 and active Caspase-1 (p10) protein levels were significantly increased (P = 0.014 and P = 0.049). ELISA revealed significantly increased IL-1α (mean = 6.34 vs 0.01 pg/ml) and IL-1ß plasma levels (mean = 12.07 vs. 0.04 pg/ml) in AAA patients. The data indicate that male PBMC display a systemic proinflammatory state with primed inflammasomes that may contribute to AAA-pathogenesis. The AAA-specific inflammasome activation pattern suggests differential regulation of the sensors AIM2 and NLRP3 in inflammatory cells of AAA patients.

A Glyoxalase-1 Knockdown Does Not Have Major Short Term Effects on Energy Expenditure and Atherosclerosis in Mice.

Objective. Glyoxalase-1 is an enzyme detoxifying methylglyoxal (MG). MG is a potent precursor of advanced glycation endproducts which are regarded to be a key player in micro- and macrovascular damage. Yet, the role of Glo1 in atherosclerosis remains unclear. In this study, the effect of Glo1 on mouse metabolism and atherosclerosis is evaluated. Methods. Glo1 knockdown mice were fed a high fat or a standard diet for 10 weeks. Body weight and composition were investigated by Echo MRI. The PhenoMaster system was used to measure the energy expenditure. To evaluate the impact of Glo1 on atherosclerosis, Glo1(KD) mice were crossed with ApoE-knockout mice and fed a high fat diet for 14 weeks. Results. Glo1 activity was significantly reduced in heart, liver, and kidney lysates derived from Glo1(KD) mice. Yet, there was no increase in methylglyoxal-derived AGEs in all organs analyzed. The Glo1 knockdown did not affect body weight or body composition. Metabolic studies via indirect calorimetry did not show significant effects on energy expenditure. Glo1(KD) mice crossed to ApoE(-/-) mice did not show enhanced formation of atherosclerosis. Conclusion. A Glo1 knockdown does not have major short term effects on the energy expenditure or the formation of atherosclerotic plaques.

Gene expression of inflammasome components in peripheral blood mononuclear cells (PBMC) of vascular patients increases with age.

BACKGROUND: Chronic low-grade inflammation is considered a driver of many age-related disorders, including vascular diseases (inflammaging). Inhibition of autophagic capacity with ageing was postulated to generate a pro-inflammatory condition via activation of inflammasomes, a group of Interleukin-1 activating intracellular multi-protein complexes. We thus investigated gene expression of inflammasome components in PBMC of 77 vascular patients (age 22-82) in association with age. FINDINGS: Linear regression of real-time qRT-PCR data revealed a significant positive association of gene expression of each of the inflammasome components with age (Pearson correlation coefficients: AIM2: r = 0.245; P = 0.032; NLRP3: r = 0.367; P = 0.001; ASC (PYCARD): r = 0.252; P = 0.027; CASP1: r = 0.296; P = 0.009; CASP5: r = 0.453; P = 0.00003; IL1B: r = 0.247; P = 0.030). No difference in gene expression of AIM2, NLRP3, ASC CASP1, and CASP5 was detected between PBMC of patients with advanced atherosclerosis and other vascular patients, whereas IL1B expression was increased in PBMC of the latter group (P = 0.0005). CONCLUSION: The findings reinforce the systemic pro-inflammatory phenotype reported in elderly by demonstrating an increased phase-1 activation of inflammasomes in PBMC of vascular patients.

Coding Microsatellite Frameshift Mutations Accumulate in Atherosclerotic Carotid Artery Lesions: Evaluation of 26 Cases and Literature Review.

Somatic DNA alterations are known to occur in atherosclerotic carotid artery lesions; however, their significance is unknown. The accumulation of microsatellite mutations in coding DNA regions may reflect a deficiency of the DNA mismatch repair (MMR) system. Alternatively, accumulation of these coding microsatellite mutations may indicate that they contribute to the pathology. To discriminate between these two possibilities, we compared the mutation frequencies in coding microsatellites (likely functionally relevant) with those in noncoding microsatellites (likely neutral). Genomic DNA was isolated from carotid endarterectomy (CEA) specimens of 26 patients undergoing carotid surgery and from 15 nonatherosclerotic control arteries. Samples were analyzed by DNA fragment analysis for instability at three noncoding (BAT25, BAT26, CAT25) and five coding (AIM2, ACVR2, BAX, CASP5, TGFBR2) microsatellite loci, with proven validity for detection of microsatellite instability in neoplasms. We found an increased frequency of coding microsatellite mutations in CEA specimens compared with control specimens (34.6 versus 0%; p = 0.0013). Five CEA specimens exhibited more than one frameshift mutation, and ACVR2 and CASP5 were affected most frequently (5/26 and 6/26). Moreover, the rate of coding microsatellite alterations (15/130) differed significantly from that of noncoding alterations (0/78) in CEA specimens (p = 0.0013). In control arteries, no microsatellite alterations were observed, neither in coding nor in noncoding microsatellite loci. In conclusion, the specific accumulation of coding mutations suggests that these mutations play a role in the pathogenesis of atherosclerotic carotid lesions, since the absence of mutations in noncoding microsatellites argues against general microsatellite instability, reflecting MMR deficiency.

Gender difference in glyoxalase 1 activity of atherosclerotic carotid artery lesions.

OBJECTIVE: Age and gender are two factors that determine the risk of atherosclerosis. The latter effect is only partly understood. Dicarbonyls, in particular methylglyoxal, participate in the development of atherosclerosis, and their major detoxification route is the enzyme glyoxalase 1 (GLO1), which is known to decrease during aging. METHODS: GLO1 expression and activity were studied in atherosclerotic carotid artery lesions of 71 patients with respect to demographic and clinical characteristics. RESULTS: GLO1 activity was nonsignificantly reduced by >50% in individuals with carotid artery disease compared with control individuals. There was no significant difference in GLO1 expression between the groups; however, the GLO1 activity-to-protein ratio showed a significant reduction for the carotid artery disease patients compared with the controls. The reduction in the GLO1 activity-to-protein ratio was more pronounced in men and was associated with increased inflammation shown by a significant elevation in the expression-level of interleukin-1ß. CONCLUSIONS: These data suggest that GLO1 is regulated on the post-translational level by factors such as gender as well as factors that affect the overall burden of atherosclerosis.

Finite element analysis of abdominal aortic aneurysms: predicted rupture risk correlates with aortic wall histology in individual patients.

PURPOSE: To evaluate a finite element analysis (FEA) model as a predictive tool for abdominal aortic aneurysm (AAA) rupture risk assessment. METHODS: FEA of asymptomatic infrarenal AAAs in 15 men (mean age 72 years) was performed preoperatively using semiautomatic finite element analysis software (A4clinics) to calculate peak wall stress (PWS) and regions of highest and lowest rupture risk index (RRI). The areas of high and low RRI identified on the preoperative FEA were sampled during open surgery; aortic wall specimens were prepared for histological analysis. A semiquantitative score compared the histological findings from high and low rupture risk samples. RESULTS: Significant correlation was found between histological AAA wall integrity and RRI in individual patients. AAA wall regions with highest RRI showed advanced histological disintegrity compared to regions with lower RRI within the same AAA: mean smooth muscle cells: 0.43 vs. 1.21, respectively (p=0.031); elastic fibers: 0.57 vs. 1.29, respectively (p=0.008); cholesterol plaque: 2.60 vs. 2.20, respectively (p=0.034); and calcified plaque: 2.27 vs. 1.40, respectively (p=0.017). The amount of calcified plaque was significantly correlated with PWS (r=0.528, p=0.043) by univariate regression analysis. However, there was no correlation between PWS or RRI and the histological findings between patients. CONCLUSION: These preliminary results show that high rupture risk regions estimated by FEA contain increased histopathological degeneration compared to low rupture risk samples within the same AAA. Until now, the role of FEA in predicting individual AAA rupture risk has not been established as a validated diagnostic tool. However, these data provide promising results for FEA model verification.