Control Aortas Research Articles

IRAP inhibition using HFI419 prevents moderate to severe acetylcholine mediated vasoconstriction in a rabbit model

Coronary artery vasospasm (constriction) caused by reduced nitric oxide bioavailability leads to myocardial infarction. Reduced endothelial release of nitric oxide by the neurotransmitter acetylcholine, leads to paradoxical vasoconstriction as it binds to smooth muscle cell M3 receptors. Thus, inhibition of coronary artery vasospasm will improve clinical outcomes. Inhibition of insulin regulated aminopeptidase has been shown to improve vessel function, thus we tested the hypothesis that HFI419, an inhibitor of insulin regulated aminopeptidase, could reduce blood vessel constriction to acetylcholine. The abdominal aorta was excised from New Zealand white rabbits (n=15) and incubated with 3mM Hcy to induce vascular dysfunction in vitro for 1h. HFI419 was added 5min prior to assessment of vascular function by cumulative doses of acetylcholine. In some rings, vasoconstriction to acetylcholine was observed in aortic rings after pre-incubation with 3mM homocysteine. Incubation with HFI419 inhibited the vasoconstrictive response to acetylcholine, thus improving, but not normalizing, vascular function (11.5±8.9% relaxation vs 79.2±37% constriction, p<0.05). Similarly, in another group with mild vasoconstriction, HFI419 inhibited this effect (34.9±4.6% relaxation vs 11.1±5.2%, constriction, p<0.05). HFI419 had no effect on control aorta or aorta with mild aortic dysfunction. The present study shows that HFI419 prevents acetylcholine mediated vasoconstriction in dysfunctional blood vessels. HFI419 had no effect on normal vasodilation. Our results indicate a therapeutic potential of HFI419 in reducing coronary artery vasospasm.

Tauroursodeoxycholic Acid Attenuates Angiotensin II Induced Abdominal Aortic Aneurysm Formation in Apolipoprotein E-deficient Mice by Inhibiting Endoplasmic Reticulum Stress

Abdominal aortic aneurysm (AAA) is characterised by the infiltration of smooth muscle cell (SMC) apoptosis, inflammatory cells, neovascularisation, and degradation of the extracellular matrix. Previous work has shown that endoplasmic reticulum (ER) stress and SMC apoptosis were increased both in a mouse model and human thoracic aortic aneurysm. However, whether the ER stress is activated in AAA formation and whether suppressing ER stress attenuates AAA is unknown. Human AAA and control aorta samples were collected. Expression of ER stress chaperones glucose-regulated protein (GRP)-78 and GRP-94 was detected by immunohistochemical staining. The effect of ER stress inhibitor tauroursodeoxycholic acid (TUDCA) on AAA formation in angiotensin (Ang) II induced apolipoprotein E-/- mice was explored. Elastin staining was used to observe the rupture of elastic fragmentation. Immunohistochemistry and Western blot analysis were performed, to detect the protein expression of ER stress chaperones and apoptosis molecules. There was significant upregulation of GRP-78 and GRP-94 in aneurysmal areas of human AAA and Ang II induced ApoE-/- mice (p<.05). TUDCA significantly attenuated the maximum diameters of abdominal aortas in Ang II induced ApoE-/- mice (p<.05). TUDCA significantly reduced expression of ER stress chaperones and the apoptotic cell numbers (p<.05). Furthermore, TUDCA significantly reduced expression of apoptosis molecules, such as caspase-3, caspase-12, C/EBP homologous protein, c-Jun N-terminal kinase activating transcription factor 4, X-box binding protein, and eukaryotic initiation factor 2α in Ang II induced ApoE-/- mice (p<.05). The results suggest that ER stress is involved in human and Ang II induced AAA formation in ApoE-/- mice. TUDCA attenuates Ang II induced AAA formation in ApoE-/- mice by inhibiting ER stress mediated apoptosis.

Differential expression of sex hormone receptors in abdominal aortic aneurysms

ObjectiveMale sex is a significant risk factor for abdominal aortic aneurysm (AAA). Female sex hormones have been reported to prevent aneurysm formation in animal models. The study aims to describe the expression profile of sex hormone receptors in the aneurysm wall of men and women with AAA and compare with unaffected controls. MethodsAneurysm wall biopsies were obtained during elective open repair of AAA in men and women (n=16+16). Aortic vessel wall from controls were obtained at organ donation (n=6). Western blot-, mRNA expression- and immunohistochemical analyses were performed to assess the expression profile of the sex hormone receptors – androgen receptor (AR), progesterone receptor (PR), estrogen receptor α (ERα) and β (ERβ). ResultsThe mRNA- and protein expression levels of AR were higher in AAA compared with control aorta (7.26 vs. 5.14, P=0.001). mRNA- and protein expression levels of ERβ were lower in AAA compared with control aorta (9.15 vs. 12.29, P<0.001). mRNA expression levels of PR were higher in AAA compared with control aorta (8.73 vs. 6.21, P=0.003), but could not be confirmed on protein level. The expression profile of sex hormone receptors in men and women with AAA was similar. ConclusionExpression of sex hormone receptors differs in the aneurysmal aorta compared with unaffected aorta in men and women. A higher expression of AR and a lower expression of ERβ suggest that sex hormone activity could be associated with aneurysm development.

Proteomic analysis reveals downregulation of housekeeping proteins in the diabetic vascular proteome.

Type 2 diabetes (T2D) increases the risk of death associated with cardiovascular complications. However, a complete understanding of protein changes within the diabetic vasculature is still lacking. Herein, we utilized mass spectrometry to perform vascular and urinary proteome analysis using a rat model of high-fat feeding and low-dose streptozotocin to simulate late-stage T2D. The purpose of this study was to identify aortic and urine proteins that are differentially expressed in normal and T2D rats. High-fat feeding and low-dose streptozotocin resulted in hyperglycemia, hypoinsulinemia and high levels of circulating free fatty acids. Using a shotgun proteomic approach, high-mobility-group protein B1 and spondin-1 were significantly increased in T2D aorta compared to control aorta, suggesting vascular inflammation and smooth muscle proliferation, respectively. However, the majority of differentially expressed aortic proteins were downregulated in T2D, including proteins associated with coagulation, cell differentiation and redox homeostasis. Strikingly, we report a significant downregulation of commonly used cytoskeletal housekeeping proteins in T2D aorta. Urine from T2D rats displayed increased expression of proteins involved in inflammation and oxidative stress and decreased expression of proteins associated with lipid metabolism and cell adhesion. A number of differentially expressed proteins in urine of T2D rats have previously been reported in human T2D, thereby supporting this animal model as a good representation of human T2D. Our data offer new information regarding key pathways that could be therapeutically targeted to combat the cardiovascular complications of T2D.

Resuscitative endovascular balloon occlusion of the aorta for control of noncompressible truncal hemorrhage in the abdomen and pelvis

BackgroundNoncompressible truncal hemorrhage is a leading cause of potentially preventable death in trauma and acute care surgery patients. These patients are at high risk of exsanguination before potentially life-saving surgical intervention may be performed. Temporary aortic occlusion is an effective means of augmenting systolic blood pressure and perfusion of the heart and brain in these patients. Aortic occlusion temporarily controls distal bleeding until permanent hemostasis can be achieved. The traditional method for temporary aortic occlusion is via resuscitative thoracotomy with cross clamping of the descending aorta. While effective, resuscitative thoracotomy is highly invasive and may worsen blood loss, hypothermia, and coagulopathy by opening an otherwise uninjured body cavity. Resuscitative endovascular balloon occlusion of the aorta (REBOA) achieves temporary aortic occlusion using an occlusive balloon catheter that is introduced into the aorta via endovascular access of the common femoral artery. For this reason it is thought that REBOA could provide a less-invasive method for temporary aortic occlusion. Our purpose is to describe our experience with the implementation of REBOA at our Level 1 trauma center. MethodsA retrospective case series describing all cases of REBOA performed at a prominent level 1 trauma center between October 2011 and September 2015. The study inclusion criteria were any patient that received a REBOA procedure in the acute phases after injury. There were no exclusion criteria. Data were collected from electronic medical records and the hospital's trauma registry. ResultsA total of 31 patients underwent REBOA during the study period. The median age of REBOA patients was 47 (interquartile range [IQR] = 27 to 63) and 77% were male. A majority (87%) of patients sustained blunt trauma. The median injury severity score was 34 (IQR = 22 to 42). The overall survival rate was 32% but varied greatly between subgroups. Balloon inflation resulted in a median increase in systolic blood pressure of 55-mm Hg (IQR 33 to 60), in cases where the data were available (n = 20). A return to spontaneous circulation was noted in 60% of patients who had arrested before REBOA (n = 10). Overall, early death by hemorrhage was 28% with only 2 deaths in the emergency department before reaching the operating room. ConclusionsREBOA is an effective method for achieving temporary aortic occlusion in trauma patients with noncompressible truncal hemorrhage. Balloon inflation correlated with increased blood pressure and temporary hemorrhage control in a vast majority of patients.

Characterisation and vascular expression of nitric oxide synthase 3 in amphibians.

In mammals, nitric oxide (NO) produced by nitric oxide synthase 3 (NOS3) localised in vascular endothelial cells is an important vasodilator but the presence of NOS3 in the endothelium of amphibians has been concluded to be absent, based on physiological studies. In this study, a nos3 cDNA was sequenced from the toad, Rhinella marina. The open reading frame of R. marina nos3 encoded an 1170 amino acid protein that showed 81% sequence identity to the recently cloned Xenopus tropicalis nos3. Rhinella marina nos3 mRNA was expressed in a range of tissues and in the dorsal aorta and pulmonary, mesenteric, iliac and gastrocnemius arteries. Furthermore, nos3 mRNA was expressed in the aorta of Xenopus laevis and X. tropicalis. Quantitative real-time PCR showed that removal of the endothelium of the lateral aorta of R. marina significantly reduced the expression of nos3 mRNA compared to control aorta with the endothelium intact. However, in situ hybridisation was not able to detect any nos3 mRNA in the dorsal aorta of R. marina. Immunohistochemistry using a homologous R. marina NOS3 antibody showed immunoreactivity (IR) within the basal region of many endothelial cells of the dorsal aorta and iliac artery. NOS3-IR was also observed in the proximal tubules and collecting ducts of the kidney but not within the capillaries of the glomeruli. This is the first study to demonstrate that vascular endothelial cells of an amphibian express NOS3.

Altered PPARγ Coactivator-1 Alpha Expression in Abdominal Aortic Aneurysm: Possible Effects on Mitochondrial Biogenesis

Introduction: Abdominal aortic aneurysm (AAA) is a complex and deadly vascular disorder. The pathogenesis of AAA includes destruction and phenotypic alterations of the vascular smooth muscle cells (VSMCs) and aortic tissues. PPARγ coactivator-1 alpha (PGC1α) regulates VSMC migration and matrix formation and is a major inducer of mitochondrial biogenesis and function, including oxidative metabolism. Methods: Protein and gene expression of PGC1α and markers for mitochondria biogenesis and cell type-specificity were analysed in AAA aortas from humans and mice and compared against control aortas. Results: Gene expression of PPARGC1A was decreased in human AAA and angiotensin (Ang) II-induced AAA in mice when compared to control vessels. However, high expression of PGC1α was detected in regions of neovascularisation in the adventitia layer. In contrast, the intima/media layer of AAA vessel exhibited defective mitochondrial biogenesis as indicated by low expression of PPARGC1A, VDAC, ATP synthase and citrate synthase. Conclusion: Our results suggest that mitochondrial biogenesis is impaired in AAA in synthetic SMCs in the media, with the exception of newly formed supporting vessels in the adventitia where the mitochondrial markers seem to be intact. To our knowledge, this is the first study investigating PGC1α and mitochondria biogenesis in AAA.

Management of Intra-Abdominal Hemorrhagic Shock Using REBOA

Hemorrhage is the leading cause of potentially preventable death after a traumatic injury. 1 Scott DJ Eliason JL Villamaria C et al. A novel fluoroscopy-free, resuscitative endovascular aortic balloon occlusion system in a model of hemorrhagic shock. J Trauma Acute Care Surg. 2013; 75: 122-128 Crossref PubMed Scopus (104) Google Scholar , 2 Brenner ML Moore LJ DuBose JJ et al. A clinical series of resuscitative endovascular balloon occlusion of the aorta for hemorrhage control and resuscitation. J Trauma Acute Care Surg. 2013; 75: 506-511 Crossref PubMed Google Scholar , 3 Norii T Crandall C Terasaka Y Survival of severe blunt trauma patients treated with resuscitative endovascular balloon occlusion of the aorta compared with propensity score-adjusted untreated patients. J Trauma Acute Care Surg. 2015; 78: 721-728 Crossref PubMed Scopus (141) Google Scholar Noncompressible torso hemorrhage (NCTH), which is a disruption of the vascular activity of the axial torso vessels, pulmonary parenchyma, solid organs, or the bony pelvis, accompanied by shock, 4 Morrison JJ Stannard A Rasmussen TE et al. Injury pattern and mortality of noncompressible torso hemorrhage in UK combat casualties. J Trauma Acute Care Surg. 2013; 75: S263-S268 Crossref PubMed Scopus (79) Google Scholar has an associated mortality of approximately 45%. 5 Kisat M Morrison JJ Hashmi ZG et al. Epidemiology and outcomes of non-compressible torso hemorrhage. J Surg Res. 2013; 184: 414-421 Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar A significant number of these deaths often occur because of the delay in definitive hemorrhage control in an operative theater or interventional radiology suite. Therefore, a need for adjunct hemorrhage control is paramount to attaining temporary control of bleeding until definitive hemostasis can be achieved. 3 Norii T Crandall C Terasaka Y Survival of severe blunt trauma patients treated with resuscitative endovascular balloon occlusion of the aorta compared with propensity score-adjusted untreated patients. J Trauma Acute Care Surg. 2015; 78: 721-728 Crossref PubMed Scopus (141) Google Scholar , 4 Morrison JJ Stannard A Rasmussen TE et al. Injury pattern and mortality of noncompressible torso hemorrhage in UK combat casualties. J Trauma Acute Care Surg. 2013; 75: S263-S268 Crossref PubMed Scopus (79) Google Scholar , 5 Kisat M Morrison JJ Hashmi ZG et al. Epidemiology and outcomes of non-compressible torso hemorrhage. J Surg Res. 2013; 184: 414-421 Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar A key to improving outcomes in patients with NCTH is a “bundle” of measures that can facilitate early diagnosis, rapid control of hemorrhage, systemic and topical hemostatic support, and a short time at the scene. In the past decade a paradigm shift has occurred in treatment strategies and transfusion algorithms, with emphasis on hemostatic or damage control resuscitation. 2 Brenner ML Moore LJ DuBose JJ et al. A clinical series of resuscitative endovascular balloon occlusion of the aorta for hemorrhage control and resuscitation. J Trauma Acute Care Surg. 2013; 75: 506-511 Crossref PubMed Google Scholar , 6 Stannard A Eliason JL Rasmussen TE Resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct for hemorrhagic shock. J Trauma. 2011; 71: 1869-1872 Crossref PubMed Scopus (355) Google Scholar Jennifer Adamski is Assistant Professor, Clinical Track, Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA.

Varicella Zoster Virus Infection in Granulomatous Arteritis of the Aorta.

Granulomatous arteritis characterizes the pathology of giant cell arteritis, granulomatous aortitis, and intracerebral varicella zoster virus (VZV) vasculopathy. Because intracerebral VZV vasculopathy and giant cell arteritis are strongly associated with productive VZV infection in cerebral and temporal arteries, respectively, we evaluated human aortas for VZV antigen and VZV DNA. Using 3 different anti-VZV antibodies, we identified VZV antigen in 11 of 11 aortas with pathologically verified granulomatous arteritis, in 1 of 1 cases of nongranulomatous arteritis, and in 5 of 18 control aortas (28%) obtained at autopsy. The presence of VZV antigen in granulomatous aortitis was highly significant (P = .0001) as compared to control aortas, in which VZV antigen was never associated with pathology, indicating subclinical reactivation. VZV DNA was found in most aortas containing VZV antigen. The frequent clinical, radiological, and pathological aortic involvement in patients with giant cell arteritis correlates with the significant detection of VZV in granulomatous aortitis.

αVβ3 integrin-targeted microSPECT/CT imaging of inflamed atherosclerotic plaques in mice.

BackgroundαVβ3-integrin is expressed by activated endothelial cells and macrophages in atherosclerotic plaques and may represent a valuable marker of high-risk plaques. We evaluated 99mTc-maraciclatide, an integrin-specific tracer, for imaging vascular inflammation in atherosclerotic lesions in mice.MethodsApolipoprotein E-negative (ApoE−/−) mice on a Western diet (n = 10) and normally fed adult C57BL/6 control mice (n = 4) were injected with 99mTc-maraciclatide (51.8 ± 3.7 MBq). A blocking peptide was infused in three ApoE−/− mice; this condition served as another control. After 90 min, the animals were imaged via single-photon emission computed tomography (SPECT). While maintained in the same position, the mice were transferred to computed tomography (CT) to obtain contrast-enhanced images of the aortic arch. Images from both modalities were fused, and signal was quantified in the aortic arch and in the vena cava for subtraction of blood-pool activity. The aorta was carefully dissected after imaging for gamma counting, autoradiography, and histology.ResultsTracer uptake was significantly higher in ApoE−/− mice than in both groups of control mice (1.56 ± 0.33 vs. 0.82 ± 0.24 vs. 0.98 ± 0.11, respectively; P = 0.006). Furthermore, higher tracer activity was detected via gamma counting in the aorta of hypercholesterolemic mice than in both groups of control mice (1.52 ± 0.43 vs. 0.78 ± 0.19 vs. 0.47 ± 0.31 99mTc-maraciclatide %ID/g, respectively; P = 0.018). Autoradiography showed significantly higher tracer uptake in the atherosclerotic aorta than in the control aorta (P = 0.026). Finally, in the atherosclerotic aorta, immunostaining indicated that the integrin signal came predominantly from macrophages and was correlated with the macrophage CD68 immunomarker (r = 0.73).Conclusions99mTc-maraciclatide allows in vivo detection of inflamed atherosclerotic plaques in mice and may represent a non-invasive approach for identifying high-risk plaques in patients.

Inflammatory cells, ceramides, and expression of proteases in perivascular adipose tissue adjacent to human abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a deadly irreversible weakening and distension of the abdominal aortic wall. The pathogenesis of AAA remains poorly understood. Investigation into the physical and molecular characteristics of perivascular adipose tissue (PVAT) adjacent to AAA has not been done before and is the purpose of this study. Human aortae, periaortic PVAT, and fat surrounding peripheral arteries were collected from patients undergoing elective surgical repair of AAA. Control aortas were obtained from recently deceased healthy organ donors with no known arterial disease. Aorta and PVAT was found in AAA to larger extent compared with control aortas. Immunohistochemistry revealed neutrophils, macrophages, mast cells, and T-cells surrounding necrotic adipocytes. Gene expression analysis showed that neutrophils, mast cells, and T-cells were found to be increased in PVAT compared with AAA as well as cathepsin K and S. The concentration of ceramides in PVAT was determined using mass spectrometry and correlated with content of T-cells in the PVAT. Our results suggest a role for abnormal necrotic, inflamed, proteolytic adipose tissue to the adjacent aneurysmal aortic wall in ongoing vascular damage.

Early life stress in male mice induces superoxide production and endothelial dysfunction in adulthood.

Early life stress (ELS) is a risk for cardiovascular disease in adulthood although very little mechanistic insight is available. Because oxidative stress and endothelial dysfunction are major contributors to cardiovascular risk, we hypothesized that ELS induces endothelial dysfunction in adult male mice via increased superoxide production. Studies employed a mouse model of ELS, maternal separation with early weaning (MSEW), in which litters were separated from the dam for 4 h/day [postnatal days (PD) 2-5] and 8 h/day (PD6-16), and weaned at PD17. Control litters remained undisturbed until weaning at PD21. When compared with control mice, thoracic aortic rings from adult male MSEW mice displayed significant endothelial dysfunction that was reversed by the superoxide scavenger, polyethylene glycol-superoxide dismutase (PEG-SOD). PEG-SOD-inhibitable superoxide production by aortae from MSEW mice was significantly greater than observed in control aortae, although unaffected by nitric oxide synthase inhibition, suggesting that uncoupled nitric oxide synthase was not responsible for the accelerated superoxide production. Aortic SOD expression, plasma SOD activity, and total antioxidant activity were similar in MSEW and control mice, indicating unaltered antioxidant capacity in MSEW mice. Increased expression of the NADPH oxidase subunits, NOX2 and NOX4, was evident in the aortae of MSEW mice. Moreover, endothelial dysfunction and superoxide production in MSEW mice was reversed with the NADPH oxidase inhibitor, apocynin, indicating increased NADPH oxidase-dependent superoxide production and endothelial dysfunction. The finding that MSEW induces superoxide production and endothelial dysfunction in adult mice may provide a mechanistic link between ELS and adult cardiovascular disease risk.

Changes in Angiotensin Receptor Distribution and in Aortic Morphology Are Associated with Blood Pressure Control in Aged Metabolic Syndrome Rats.

The role of the renin-angiotensin system (RAS) in blood pressure regulation in MS during aging is unknown. It participates in metabolic syndrome (MS) and aging regulating vascular tone and remodeling. RAS might participate in a compensatory mechanism decreasing blood pressure and allowing MS rats to reach 18 months of age and it might form part of therapeutical procedures to ameliorate MS. We studied histological changes and distribution of RAS receptors in aortas of MS aged rats. Electron microscopy images showed premature aging in MS since the increased fibrosis, enlarged endothelium, and invasion of this layer by muscle cells that was present in control 18-month-old aortas were also found in 6-month-old aortas from MS rats. AT1, AT2, and Mas receptors mediate the effects of Ang II and Ang 1-7, respectively. Fluorescence from AT2 decreased with age in control and MS aortas, while fluorescence of AT1 increased in aortas from MS rats at 6 months and diminished during aging. Mas expression increased in MS rats and remained unchanged in control rats. In conclusion, there is premature aging in the aortas from MS rats and the elevated expression of Mas receptor might contribute to decrease blood pressure during aging in MS.

NG2 Proteoglycan Ablation Reduces Foam Cell Formation and Atherogenesis via Decreased Low-Density Lipoprotein Retention by Synthetic Smooth Muscle Cells.

Obesity and hyperlipidemia are critical risk factors for atherosclerosis. Because ablation of NG2 proteoglycan in mice leads to hyperlipidemia and obesity, we investigated the impact of NG2 ablation on atherosclerosis in apoE null mice. Immunostaining indicates that NG2 expression in plaque, primarily by synthetic smooth muscle cells, increases during atherogenesis. NG2 ablation unexpectedly results in decreased (30%) plaque development, despite aggravated obesity and hyperlipidemia. Mechanistic studies reveal that NG2-positive plaque synthetic smooth muscle cells in culture can sequester low-density lipoprotein to enhance foam-cell formation, processes in which NG2 itself plays direct roles. In agreement with these observations, low-density lipoprotein retention and lipid accumulation in the NG2/ApoE knockout aorta is 30% less than that seen in the control aorta. These results indicate that synthetic smooth muscle cell-dependent low-density lipoprotein retention and foam cell formation outweigh obesity and hyperlipidemia in promoting mouse atherogenesis. Our study sheds new light on the role of synthetic smooth muscle cells during atherogenesis. Blocking plaque NG2 or altering synthetic smooth muscle cells function may be promising therapeutic strategies for atherosclerosis.

THE DIRECTIONAL DEPENDENCY OF ASCENDING AORTA BIOMECHANICS DISAPPEARS WITH SEVERE MEDIAL DEGENERATION

The study of biomechanics can potentially provide insight into the pathogenesis of aortic complications and improve risk assessment. Aortas are described to have anisotropy, the directional dependency of mechanical properties. We hypothesize that disease-related remodelling of the aortic wall microstructure found in ascending aortic aneurysms results in changes in anisotropy. Excised aneurysmal ascending aortic tissue was obtained at the time of surgery and control tissue was obtained at organ donation or autopsy. The tissue was subjected to biaxial tensile testing. Stress-strain relationships were collected in both the circumferential and axial directions; from this data, both the apparent modulus of elasticity and energy loss were derived. Energy loss describes normalized hysteresis between aortic loading and unloading curves. Movat pentachrome histological staining was performed on each sample and aortic wall composition was quantified colorimetrically. Energy loss was greater in the circumferential direction than in the axial direction for both aneurysmal and control aortas (p<0.0001), while the modulus of elasticity was the same in both directions. This directional dependency in energy loss became diminished in larger aortas (r2=0.15, p=0.01), especially when indexed to body surface area (r2=0.29, p=0.002), aortas with greater energy loss (r2=0.44, p<0.0001), and aortas associated with tricuspid valves (p=0.004). An inflection point was noted in disease severity separating two populations: aortas without any directional dependency in energy loss (isotropic), and those with varying degrees of anisotropy. Aortas with indexed aortic size greater than 3.5 cm/m2 or energy loss greater than 35% were uniformly isotropic. Evaluating the microstructure, aortas with elevated collagen-to-elastin ratios (greater than 2) reflecting severe medial degeneration, were also uniformly isotropic. Aneurysmal aortas with higher collagen-to-elastin ratios tended towards isotropy (r2=0.29, p=0.001). Energy loss detects the anisotropic nature of aortic tissue unlike the apparent modulus of elasticity; this is further evidence that it may be a more sensitive and physiologically relevant metric in the evaluation of aneurysmal disease. Isotropy is associated with severe medial degeneration indicating that destruction of microstructure can be captured by global biomechanics, thereby identifying energy loss isotropy as a marker of disease severity.

Resuscitative endovascular balloon occlusion of the aorta for hemorrhage control: Past, present, and future.

Resuscitative endovascular balloon occlusion of the aorta for hemorrhage control: Past, present, and future.

Detection of Apoptotic Cells in a Rabbit Model with Atherosclerosis-Like Lesions Using the Positron Emission Tomography Radiotracer [ 18 F]ML-10

[18F]ML-10 (2-(5-fluoro-pentyl)-2-methylmalonic acid) is a positron emission tomography (PET) radiotracer that accumulates in cells presenting apoptosis-specific membrane alterations. The aim of this study was to test whether [18F]ML-10 allows for the detection of apoptotic cells located in atherosclerotic plaques in rabbits. Atherosclerotic plaques were induced in the aortas of five rabbits, and five additional rabbits were used as controls. Activity in the aortas was quantified in vivo and ex vivo. The localization of [18F]ML-10 to the aortic wall was identified by autoradiography. Average target to background ratios measured in vivo by PET were higher in the aortas of atherosclerotic rabbits compared with those of control rabbits (2.00 ± 0.52 vs 1.22 ± 0.30; p < .05). Differences in [18F]ML-10 uptake between atherosclerotic and control aortas were confirmed ex vivo by PET and gamma counting (23.9 ± 11.2 vs 1.1 ± 2.4 counts/pixel; p <.05; 3.6 ± 2.0 vs 0.05 ± 0.05 % of injected activity/g; p < .05, respectively). Strong correlation was observed between the accumulation of [18F]ML-10 in aortic segments as detected by autoradiography and the number of apoptotic cells on corresponding histologic sections (r2 = .75; p < .05). In this study, we found that atherosclerotic plaques rich in apoptotic cells can be detected with [18F]ML-10 and PET.

Molecular anatomy of ascending aorta in atherosclerosis by MS Imaging: Specific lipid and protein patterns reflect pathology

The molecular anatomy of healthy and atherosclerotic tissue is pursued here to identify ongoing molecular changes in atherosclerosis development. Subclinical atherosclerosis cannot be predicted and novel therapeutic targets are needed. Mass spectrometry imaging (MSI) is a novel unexplored ex vivo imaging approach in CVD able to provide in-tissue molecular maps. A rabbit model of early atherosclerosis was developed and high-spatial-resolution MALDI-MSI was applied to comparatively analyze histologically-based arterial regions of interest from control and early atherosclerotic aortas. Specific protocols were applied to identify lipids and proteins significantly altered in response to atherosclerosis. Observed protein alterations were confirmed by immunohistochemistry in rabbit tissue, and additionally in human aortas. Molecular features specifically defining different arterial regions were identified. Localized in the intima, increased expression of SFA and lysolipids and intimal spatial organization showing accumulation of PI, PG and SM point to endothelial dysfunction and triggered inflammatory response. TG, PA, SM and PE-Cer were identified specifically located in calcified regions. Thymosin β4 (TMSB4X) protein was upregulated in intima versus media layer and also in response to atherosclerosis. This overexpression and localization was confirmed in human aortas. In conclusion, molecular histology by MS Imaging identifies spatial organization of arterial tissue in response to atherosclerosis.

Artery Tertiary Lymphoid Organs Control Aorta Immunity and Protect against Atherosclerosis via Vascular Smooth Muscle Cell Lymphotoxin β Receptors

SummaryTertiary lymphoid organs (TLOs) emerge during nonresolving peripheral inflammation, but their impact on disease progression remains unknown. We have found in aged Apoe−/− mice that artery TLOs (ATLOs) controlled highly territorialized aorta T cell responses. ATLOs promoted T cell recruitment, primed CD4+ T cells, generated CD4+, CD8+, T regulatory (Treg) effector and central memory cells, converted naive CD4+ T cells into induced Treg cells, and presented antigen by an unusual set of dendritic cells and B cells. Meanwhile, vascular smooth muscle cell lymphotoxin β receptors (VSMC-LTβRs) protected against atherosclerosis by maintaining structure, cellularity, and size of ATLOs though VSMC-LTβRs did not affect secondary lymphoid organs: Atherosclerosis was markedly exacerbated in Apoe−/−Ltbr−/− and to a similar extent in aged Apoe−/−Ltbrfl/flTagln-cre mice. These data support the conclusion that the immune system employs ATLOs to organize aorta T cell homeostasis during aging and that VSMC-LTβRs participate in atherosclerosis protection via ATLOs.

Transcriptional (ChIP-Chip) Analysis of ELF1, ETS2, RUNX1 and STAT5 in Human Abdominal Aortic Aneurysm.

We investigated transcriptional control of gene expression in human abdominal aortic aneurysm (AAA). We previously identified 3274 differentially expressed genes in human AAA tissue compared to non-aneurysmal controls. Four expressed transcription factors (ELF1, ETS2, STAT5 and RUNX1) were selected for genome-wide chromatin immunoprecipitation. Transcription factor binding was enriched in 4760 distinct genes (FDR < 0.05), of which 713 were differentially expressed in AAA. Functional classification using Gene Ontology (GO), KEGG, and Network Analysis revealed enrichment in several biological processes including “leukocyte migration” (FDR = 3.09 × 10−05) and “intracellular protein kinase cascade” (FDR = 6.48 × 10−05). In the control aorta, the most significant GO categories differed from those in the AAA samples and included “cytoskeleton organization” (FDR = 1.24 × 10−06) and “small GTPase mediated signal transduction” (FDR = 1.24 × 10−06). Genes up-regulated in AAA tissue showed a highly significant enrichment for GO categories “leukocyte migration” (FDR = 1.62 × 10−11), “activation of immune response” (FDR = 8.44 × 10−11), “T cell activation” (FDR = 4.14 × 10−10) and “regulation of lymphocyte activation” (FDR = 2.45 × 10−09), whereas the down-regulated genes were enriched in GO categories “cytoskeleton organization” (FDR = 7.84 × 10−05), “muscle cell development” (FDR = 1.00 × 10−04), and “organ morphogenesis” (FDR = 3.00 × 10−04). Quantitative PCR assays confirmed a sub-set of the transcription factor binding sites including those in MTMR11, DUSP10, ITGAM, MARCH1, HDAC8, MMP14, MAGI1, THBD and SPOCK1.