Aortic Wall Collagen Research Articles

Gasdermin D Inhibitor Necrosulfonamide Alleviates Angiotensin II-Induced Abdominal Aortic Aneurysms in Apolipoprotein E-Deficient Mice.

Abdominal aortic aneurysm (AAA) is a chronic aortic disease that lacks effective pharmacological therapies. This study was performed to determine the influence of treatment with the gasdermin D inhibitor necrosulfonamide on experimental AAAs. AAAs were induced in male apolipoprotein E-deficient mice by subcutaneous angiotensin II infusion (1000 ng/kg body weight/min), with daily administration of necrosulfonamide (5 mg/kg body weight) or vehicle starting 3 days prior to angiotensin II infusion for 30 days. Necrosulfonamide treatment remarkably suppressed AAA enlargement, as indicated by reduced suprarenal maximal external diameter and surface area, and lowered the incidence and reduced the severity of experimental AAAs. Histologically, necrosulfonamide treatment attenuated medial elastin breaks, smooth muscle cell depletion, and aortic wall collagen deposition. Macrophages, CD4+ T cells, CD8+ T cells, and neovessels were reduced in the aneurysmal aortas of necrosulfonamide- as compared to vehicle-treated angiotensin II-infused mice. Atherosclerosis and intimal macrophages were also substantially reduced in suprarenal aortas from angiotensin II-infused mice following necrosulfonamide treatment. Additionally, the levels of serum interleukin-1β and interleukin-18 were significantly lower in necrosulfonamide- than in vehicle-treated mice without affecting body weight gain, lipid levels, or blood pressure. Our findings indicate that necrosulfonamide reduced experimental AAAs by preserving aortic structural integrity as well as reducing mural leukocyte accumulation, neovessel formation, and systemic levels of interleukin-1β and interleukin-18. Thus, pharmacologically inhibiting gasdermin D activity may lead to the establishment of nonsurgical therapies for clinical AAA disease.

Effect of Cardiotonic Steroid Marinobufagenin on Vascular Remodeling and Cognitive Impairment in Young Dahl-S Rats.

The hypertensive response in Dahl salt-sensitive (DSS) rats on a high-salt (HS) diet is accompanied by central arterial stiffening (CAS), a risk factor for dementia, and heightened levels of a prohypertensive and profibrotic factor, the endogenous Na/K-ATPase inhibitor marinobufagenin (MBG). We studied the effect of the in vivo administration of MBG or HS diet on blood pressure (BP), CAS, and behavioral function in young DSS rats and normotensive Sprague–Dawley rats (SD), the genetic background for DSS rats. Eight-week-old male SD and DSS rats were given an HS diet (8% NaCl, n = 18/group) or a low-salt diet (LS; 0.1% NaCl, n = 14–18/group) for 8 weeks or MBG (50 µg/kg/day, n = 15–18/group) administered via osmotic minipumps for 4 weeks in the presence of the LS diet. The MBG-treated groups received the LS diet. The systolic BP (SBP); the aortic pulse wave velocity (aPWV), a marker of CAS; MBG levels; spatial memory, measured by a water maze task; and tissue collection for the histochemical analysis were assessed at the end of the experiment. DSS-LS rats had higher SBP, higher aPWV, and poorer spatial memory than SD-LS rats. The administration of stressors HS and MBG increased aPWV, SBP, and aortic wall collagen abundance in both strains vs. their LS controls. In SD rats, HS or MBG administration did not affect heart parameters, as assessed by ECHO vs. the SD-LS control. In DSS rats, impaired whole-heart structure and function were observed after HS diet administration in DSS-HS vs. DSS-LS rats. MBG treatment did not affect the ECHO parameters in DSS-MBG vs. DSS-LS rats. The HS diet led to an increase in endogenous plasma and urine MBG levels in both SD and DSS groups. Thus, the prohypertensive and profibrotic effect of HS diet might be partially attributed to an increase in MBG. The prohypertensive and profibrotic functions of MBG were pronounced in both DSS and SD rats, although quantitative PCR revealed that different profiles of profibrotic genes in DSS and SD rats was activated after MBG or HS administration. Spatial memory was not affected by HS diet or MBG treatment in either SD or DSS rats. Impaired cognitive function was associated with higher BP, CAS, and cardiovascular remodeling in young DSS-LS rats, as compared to young SD-LS rats. MBG and HS had similar effects on the cardiovascular system and its function in DSS and SD rats, although the rate of change in SD rats was lower than in DSS rats. The absence of a cumulative effect of increased aPWV and BP on spatial memory can be explained by the cerebrovascular and brain plasticity in young rats, which help the animals to tolerate CAS elevated by HS and MBG and to counterbalance the profibrotic effect of heightened MBG.

Thoracic aortic aneurysm in pregnancy: morphological analysis of 6 cases

Aortic dissection is rare but life-threatening complication in pregnancy, causing significant maternal and perinatal losses. Pregnancy may influence the integrity of the vessel wall and is a risk factor for dissection. There are very few data in the literature on structural changes in the aortic walls during pregnancy complicated by aortic dissection. Aim. Study of pathological features in the wall of ascending aorta (AA) during or immediately after pregnancy is presented in the article. Materials and methods. Material after surgical correction of AA in patients during pregnancy and in the early postpartum period was studied. Frozen sections were made from one part of the sample, followed by hematoxylin and eosin (H&E) staining, as well as Sudan III–IV staining to detect lipids. Paraffin sections were stained with H&E and picrofuchsin (van Gieson’s stain) for differentiation of collagen and muscle fibers, as well as fuchselin (Weigert’s elastic stain). Results. Six cases of aortic surgery during pregnancy (n = 1) and postpartum period (n = 5) were included: severe aortopathy caused by Marfan syndrome (MS) (n = 3), aortic coarctation with bicuspid aortic valve (n = 1), renal hypertension (n = 1), and pregnancy-induced hypertension (n = 1). Pathohistological studies showed that in all patients who underwent aortic surgery at the end of the third trimester in the early postpartum period changes in aortic wall collagen structure were observed. In contrast, in a pregnant woman with MS and severe aortopathy, who underwent preventive aortic surgery at 19 weeks of gestation, there were no such changes, the morphologic samples showed areas of scarring. In all 6 cases signs of lipoidosis in the AA wall were observed. All these data require further theoretical study, but clinicians are already faced with the question of the feasibility of preventive surgery in women with severe aortopathy on the preconception stage or during pregnancy. Conclusions. The specific effect of pregnancy on the AA wall leads to collagen disruption and the appearance of lipoidosis in late pregnancy, which is an important pathomorphological substrate for the occurrence of acute aortic pathology.

Angiopoietin-like proteins 8 knockout reduces intermittent hypoxia-induced vascular remodeling in a murine model of obstructive sleep apnea

ObjectiveObstructive sleep apnea (OSA) is a major risk factor for cardiovascular mortality. Apnea-induced chronic intermittent hypoxia (CIH) is a primary pathophysiological manifestation of OSA that promotes various cardiovascular alterations, such as aortic vascular remodeling. In this study, we investigated the association between angiopoietin-like proteins 8 (ANGPTL8) and CIH-induced aortic vascular remodeling in mice. MethodsC57BL/6J male mice were divided into four groups: Normoxia group, ANGPTL8−/− group, CIH group, CIH + ANGPTL8−/− group. Mice in the normoxia group and ANGPTL8−/− group received no treatment, while mice in the CIH and CIH + ANGPTL8−/− group were subjected to CIH (21%–5% O2, 180 s/cycle, 10 h/day) for 6 weeks. At the end of the experiments, intima-media thickness (IMT), elastin disorganization, and aortic wall collagen abundance were assessed in vivo. Immunohistochemistry and Western-blot were used to detect endoplasmic reticulum stress (ERS) and aortic vascular smooth muscle cell proliferation. ANGPTL8 shRNA and ANGPL8 overexpression were used in aortic vascular smooth muscle cells to investigate the mechanism of ANGPTL8 in CIH. ResultsCompared to the control group, CIH exposure significantly increased intima-media thickness (IMT), elastic fibers disorganization, and aortic wall collagen abundance. CIH also significantly increased blood pressure, induced hyperlipidemia, as well as the expression of ERS protein activating transcription factor-6 (ATF6) and aortic vascular smooth muscle cell proliferation. Contrary, ANGPTL8−/− significantly mitigated the CIH-induced vascular remodeling; ANGPTL8−/− decreased CIH-induced hypertension and hyperlipidemia, inhibited the protein expression of ATF6, and aortic vascular smooth muscle cell proliferation. Moreover, our in vitro study suggested that CIH could induce ANGPTL8 expression via hypoxia-inducible factor (HIF-1α); ANGPTL8 induced proliferation of aortic vascular smooth muscle cells via the ERS pathway. ConclusionANGPTL8−/− can prevent CIH-induced aortic vascular remodeling, probably through the inhibition of the ERS pathway. Therefore, ANGPTL8 might be a potential target in CIH-induced aortic vascular remodeling.

Abstract 13940: Using an Angiotensin Converting Enzyme Inhibitor to Treat Cardiovascular and Cognitive Decline in a Rat Model of Vascular Dementia

Background: Aged Dahl salt sensitive rats (DSS) rats represent a model of vascular dementia, i.e., they develop central arterial stiffness (CAS), hypertension, and cognitive decline. DSS rats have compromised renin-angiotensin system (RAS) which is activated with age and contributes to hypertension. This study examined whether angiotensin converting enzyme (ACE) inhibitor, lisinopril, affects CAS and cognitive functions in aged male DSS (n=26). Methods & Results: Following initial measurements at 16-mo of age (baseline; BL), DSS were administered lisinopril through their water (LISI; 15mg/kg/day, n=11) or control treatment (n=15) for 2-mo. Pulse wave velocity (PWV), a marker of CAS, and systolic blood pressure (SBP) were measured at BL and at 18-mo of age. Open field test (OFT) to assess anxiety-like behavior and Morris water maze (MWM) to assess spatial memory were performed at 18-mo, then aortae and hearts were collected and weighed. Aortic wall collagen abundance was estimated by histochemistry. Statistical analyses were performed by 2-way ANOVA mixed effects model and t-test. The data are presented as mean ± SEM. At 18-mo of age, control animals had high SBP similar to BL (187±4 vs. 184±7 mmHg), while LISI-treated DSS had lower SBP by 39±4 mmHg vs. BL (p<0.01). PWV in control rats increased from 16 to 18-mo (7.0±0.6 vs. 10.8±1.0 m/s; p<0.05), while PWV in LISI-treated DSS decreased after 2-mo of treatment (7.1±0.3 vs. 5.4±0.3 m/s; p<0.01). Lower heart weights (2.9±0.1 vs. 3.7±0.3 g/kg BW; p<0.01), aortic weights (4.4±0.1 vs. 5.0±0.2 mg/mm/kg BW; p<0.01), and aortic medial collagen abundance (14.0±0.3 vs. 19.6±1.0 % of total; p<0.01) were observed in the LISI-treated rats vs. control rats. No differences between LISI-treated and control groups at 18-mo (38±10 vs. 25±6 cm traveled in center) were found in OFT. MWM results indicated that neither group at 18-mo of age was able to learn the task and therefore could not be accurately assessed for differences in spatial memory. Conclusion: Initiation of anti-hypertensive treatment in old age was effective in reducing aortic fibrosis and lowering SBP and PWV in DSS rats. Longer treatment may be needed to improve cognitive function in this model of vascular dementia. Supported by the NIH/NIA Intramural Research Program

A novel swine model of abdominal aortic aneurysm

ObjectiveFew large-animal models exist for the study of aortic aneurysms. β-Aminopropionitrile (BAPN) is a compound known to cause aortic aneurysms by inhibiting lysyl oxidase, a collagen cross-linking enzyme. It is hypothesized that BAPN plus aneurysm induction surgery would result in significant aneurysm formation in swine with biologic properties similar to human disease. MethodsInitial experiments were performed in uncastrated male swine not treated with BAPN (surgery alone). Subsequently, uncastrated male swine were fed BAPN (0.15 g/kg) for 7 days before undergoing surgery; the infrarenal aorta was circumferentially dissected and measured, balloon dilated, and perfused with elastase (500 units) and type I collagenase (8000 units), with extraluminal elastase application. In the BAPN groups, daily BAPN feedings continued until swine harvest at postoperative days 7, 14, and 28. ResultsSwine undergoing surgery alone (n = 12) had significantly less dilation at 28 days compared with BAPN + surgery swine (51.9% ± 29.2% [0%-100%] vs 113.5% ± 30.2% [52.9%-146.2%]; P < .0003). Mean aortic dilation in animals undergoing treatment with surgery and BAPN was 86.9% ± 47.4% (range, 55.6%-157.1%), 105.4% ± 58.1% (50%-133.3%), and 113.5% ± 30.2% (52.9%-146.2%) at 7, 14, and 28 days, respectively. In the BAPN + surgery group, significant elastolysis was present at all time points, whereas aortic wall collagen content was not significantly different. Smooth muscle cells were significantly depleted at 14 and 28 days, and M1 macrophages were increased at 14 and 28 days (P < .05, all). Matrix metalloproteinase 2 was elevated at 7 days (P < .05). Multiple proinflammatory cytokines were elevated within the aortic wall of BAPN + surgery swine. ConclusionsBAPN plus surgery resulted in significantly larger aortic aneurysms than surgery alone and was critical to aneurysm formation in this novel swine model. Hallmarks of human disease, such as elastin fragmentation, smooth muscle cell depletion, macrophage infiltration, matrix metalloproteinase activation, and proinflammatory cytokine expression, were observed in BAPN-treated swine. This model better parallels many of the characteristics of human AAAs and may be suitable for prehuman drug trials.

Dietary Sodium Restriction Reduces Arterial Stiffness, Vascular TGF-β-Dependent Fibrosis and Marinobufagenin in Young Normotensive Rats.

High salt (HS) intake stimulates the production of marinobufagenin (MBG), an endogenous steroidal Na/K-ATPase ligand, which activates profibrotic signaling. HS is accompanied by a blood pressure (BP) increase in salt-sensitive hypertension, but not in normotensive animals. Here, we investigated whether HS stimulates MBG production and activates transforming growth factor-beta (TGF-β) profibrotic signaling in young normotensive rats, and whether these changes can be reversed by reducing salt to a normal salt (NS) level. Three-month old male Sprague–Dawley rats received NS for 4 and 8 weeks (0.5% NaCl; NS4 and NS8), or HS for 4 and 8 weeks (4% NaCl; HS4 and HS8), or HS for 4 weeks followed by NS for 4 weeks (HS4/NS4), n = 8/group. Systolic BP (SBP), pulse wave velocity (PWV), MBG excretion, aortic collagen 1α2, collagen 4α1 and TGF-β, Smad2, Smad3, Fli-1 mRNA, and total collagen abundance were measured at baseline (BL), and on weeks 4 and 8. Statistical analysis was performed using one-way ANOVA. SBP was not affected by HS (125 ± 5 and 126 ± 6 vs. 128 ± 7 mmHg, HS4 and HS8 vs. BL, p > 0.05). HS increased MBG (164 ± 19 vs. 103 ± 19 pmol/24 h/kg, HS4 vs. BL, p < 0.05) and PWV (3.7 ± 0.2 vs. 2.7 ± 0.2 m/s, HS4 vs. NS4, p < 0.05). HS8 was associated with a further increase in MBG and PWV, with an increase in aortic Col1a2 80%), Col4a1 (50%), Tgfb1 (30%), Smad2 (30%) and Smad3 (45%) mRNAs, and aortic wall collagen (180%) vs. NS8 (all p < 0.05). NS following HS downregulated HS-induced factors: in HS4/NS4, the MBG level was 91 ± 12 pmol/24 h/kg (twofold lower than HS8, p < 0.01), PWV was 3.7 ± 0.3 vs. 4.7 ± 0.2 m/s (HS4/NS4 vs. HS8, p < 0.05), aortic wall Tgfb1, Col1a2, Col4a1, Smad2, Smad3 mRNAs, and collagen abundance were reversed by salt reduction to the BL levels (p < 0.05). HS was associated with an activation of TGF-β signaling, aortic fibrosis and aortic stiffness accompanied by an MBG increase in the absence of SBP changes in young normotensive rats. The reduction of dietary salt following HS decreased MBG, PWV, aortic wall collagen and TGF-β. Thus, HS-induced aortic stiffness in normotensive animals occurred in the context of elevated MBG, which may activate SMAD-dependent TGF-β pro-fibrotic signaling. This data suggests that a decrease in salt consumption could help to restore aortic elasticity and diminish the risk of cardiovascular disease by reducing the production of the pro-fibrotic factor MBG.

AGE-DEPENDENT HYPERTENSION AND VASCULAR REMODELING IN DAHL-S RATS ARE ASSOCIATED WITH ELEVATED LEVELS OF MARINOBUFAGENIN AND COGNITIVE DECLINE

Objective: Age-associated hypertension and central arterial stiffening contribute to cognitive impairment. Increase in blood pressure (BP) and aortic remodeling occur in Dahl salt-sensitive rats (Dahl-S) with an advancing age even on a normal salt intake. Marinobufagenin (MBG), a novel pro-hypertensive factor, is implicated in Dahl-S hypertension. Here we determined whether age-associated arterial remodeling and hypertension implicate in cognitive decline in Dahl-S and whether these changes are accompanied by an increase in pro-hypertensive and pro-fibrotic factor MBG. Design and method: Male Sprague-Dawley rats (S-D) and Dahl-S were kept on a normal 0.5% NaCl intake (n = 8/14 per group) for the duration of the study. Systolic BP (SBP), pulse wave velocity (PWV), MBG, aortic collagen, and behavioral tests (open field test (OFT); novel object test; redundant place-cue version of the Morris water maze test (MWM); rotarod test) were assessed in 3-mo and 12-mo animals. Results: At 3-mo Dahl-S had higher SBP, PWV and aortic wall remodeling vs. 3-mo S-D. Between 3 and 12-mo both S-D and Dahl-S exhibited an increase in SBP, PWV, MBG and aortic wall collagen deposition. These parameters were significantly higher in 12-mo Dahl-S than in age-matched S-D (Table). MBG correlated with SBP in Dahl-S only (Pearson R = 0.52, p = 0.04), and with PWV in both S-D (Pearson R = 0.37, p = 0.01) and Dahl-S (Pearson R = 0.54, p = 0.04). Behaviorally, in an MWM, 12-mo DSS demonstrated impaired spatial hippocampal memory vs. 12-mo S-D. Compared to 3-mo, both 12-mo S-D and Dahl-S demonstrated an age-dependent decline in OFT activity, but 12-mo Dahl-S were more active in OFT, had more endurance during the rotarod test indicating non-impaired motor coordination, and showed increased object exploration vs. age-matched S-D (Table). Performance in behavioral tests by 12-mo hypertensive Dahl-S may suggest the development of age-associated anxiety and change in emotional status, and a decline in their spatial hippocampal memory. Conclusions: Cognitive deficit in aged hypertensive Dahl-S is limited to hippocampal-dependent spatial memory. In Dahl-S, development of age-dependent hypertension and aortic wall remodeling, occurred in context with an increase in MBG, may contribute to hippocampal spatial memory impairment, and suggested a possible implication of MBG in these declines.

Acetylsalicylic Acid Prevents Intermittent Hypoxia-Induced Vascular Remodeling in a Murine Model of Sleep Apnea.

Study objectives: Chronic intermittent hypoxia (CIH), a hallmark feature of obstructive sleep apnea (OSA), induces accelerated atherogenesis as well as aorta vascular remodeling. Although the cyclooxygenase (COX) pathway has been proposed to contribute to the cardiovascular consequences of OSA, the potential benefits of a widely employed COX-inhibitor such (acetylsalicylic acid, ASA) on CIH-induced vascular pathology are unknown. Therefore, we hypothesized that a common non-selective COX inhibitor such as ASA would attenuate the aortic remodeling induced by CIH in mice.Methods: 40 wild-type C57/BL6 male mice were randomly allocated to CIH or normoxic exposures (N) and treated with daily doses of ASA or placebo for 6 weeks. At the end of the experiments, intima-media thickness (IMT), elastin disorganization (ED), elastin fragmentation (EF), length between fragmented fiber endpoints (LFF), aortic wall collagen abundance (AC) and mucoid deposition (MD) were assessed.Results: Compared to N, CIH promoted significant increases in IMT (52.58 ± 2.82 μm vs. 46.07 ± 4.18 μm, p < 0.003), ED (25.29 ± 14.60% vs. 4.74 ± 5.37%, p < 0.001), EF (5.80 ± 2.04 vs. 3.06 ± 0.58, p < 0.001), LFF (0.65 ± 0.34% vs. 0.14 ± 0.09%, p < 0.001), AC (3.43 ± 1.52% vs. 1.67 ± 0.67%, p < 0.001) and MD (3.40 ± 2.73 μm2 vs. 1.09 ± 0.72 μm2, p < 0.006). ASA treatment mitigated the CIH-induced alterations in IMT: 44.07 ± 2.73 μm; ED: 10.57 ± 12.89%; EF: 4.63 ± 0.88; LFF: 0.25 ± 0.17% and AC: 0.90 ± 0.13% (p<0.05 for all comparisons).Conclusions: ASA prevents the CIH-induced aortic vascular remodeling, and should therefore be prospectively evaluated as adjuvant treatment in patients with OSA.

Abstract 17153: Increased Atherosclerotic Plaque Instability in Advanced Atherosclerosis with Aging: the Role of Calpain 2 in SOD2-deficient ApoE-/- Mice

The prevalence of atherosclerosis and incidence of cardiovascular events increase with advancing age. Increased generation and/or decreased scavenging of reactive oxygen species (ROS) in the vascular wall are major determinants of vascular disease progression. We previously showed that SOD2 deficiency in aging increases vascular oxidative stress and reduces aortic compliance, while young ApoE-/-/SOD2+/- mice show increased mitochondrial DNA damage and accelerated atherogenesis. Here we investigated the effects of aging and SOD2 deficiency on atherosclerosis and vascular wall morphology in ApoE-/- mice. Compared with the control ApoE-/-, aged ApoE-/-/SOD2+/- mice had increased total vascular wall (P &lt; 0.001) and mitochondrial ROS levels (P &lt; 0.05) and 70% higher atherosclerotic lesion area (P &lt; 0.001). Pulse wave velocity (P &lt; 0.001) and aortic wall collagen content (P &lt; 0.05) were significantly increased, while atherosclerotic plaque fibrous cap thickness (P &lt; 0.01) and vascular smooth muscle cell (VSMC)-positive area (P &lt; 0.01) were decreased in aged ApoE-/-/SOD2+/- mice. Immunofluorescence analysis of atherosclerotic lesions revealed higher levels of calpain 2, a cysteine protease implicated in apoptosis and cleaved caspase-3 localized in smooth muscle-positive areas of the plaque in aged ApoE-/-/SOD2+/- mice. VSMC isolated from aged SOD2+/- had higher levels of mitochondrial oxidative stress and dysfunction compared with VSMC from wild-type mice, as determined by increased superoxide generation and mitochondrial protein carbonylation and lower complex I and III activity. The calpain 2 protein levels were significantly higher in the SOD2+/- VSMCs compared with the wild-type cells and its expression and activity increased after TNF-α treatment, causing apoptosis. TNF-α increased MMP2 activity in SOD2+/- VSMC in Calpain 2-dependent manner. In conclusion, enhanced mitochondrial oxidative stress in aging increases aortic stiffening, atherosclerotic burden and plaque instability in advanced atherosclerosis, in part, via the activation of calpain 2 and MMP2. Targeting mitochondrial oxidative stress and calpain 2 activity may be a viable strategy to prevent aging-associated atherosclerosis complications.

Diabetics Are Less Likely to Develop Thoracic Aortic Dissection: A 10-Year Single-Center Analysis

Diabetes mellitus (DM) is an acknowledged risk factor for atherosclerosis, and diabetics are more likely to have hypertension. Atherosclerosis and hypertension are risk factors for aortic dissection. However, recent studies have shown that DM is associated with changes in aortic wall collagen. In this retrospective study we assess the relationship between DM and thoracic aortic dissection (TAD). Patients with a diagnosis of thoracic aortic dissection during the last 10 years were identified from our hospital records. The prevalence of DM in Stanford type A and B TAD was compared with that of two age- and gender-matched control groups. For every diabetic dissection case, 10 controls were selected from the hospital data. Two hundred nineteen patients (median age 61 years, male:female ratio 145:74) were identified with TAD, comprising 131 type A dissections and 88 type B dissections. Only 3 of 131 (2.3%) type A aortic dissections were diabetics, whereas, in control group 1, 241 of 1310 (18.4%) were diabetics and, in control group 2, 116 of 1310 (8.9%) were diabetics [odds ratios: 0.1 (0.03-0.32) and 0.24 (0.07-0.76), respectively] (P = 0.0001 and 0.007, respectively). Similarly, only 2 of 88 (2.3%) type B aortic dissections were diabetics, whereas 228 of 880 (26.0%) and 102 of 880 (11.6%) were diabetics in groups 1 and 2 [odds ratios: 0.07 (0.02-0.27) and 0.18 (0.04-0.73), respectively] (P = 0.0001 and 0.0035, respectively). All these odds ratios were statistically significant (P < 0.01). Patients with thoracic aortic dissection are less likely to be diabetic. Although we identified association only, not causality, it is possible that DM, or its treatment, has a protective effect against aortic dissection.

Hypertensive Changes Within the Aortic Arch of Infants and Children With Isolated Coarctation

Despite repair, a significant proportion of patients with coarctation of the aorta (CoA) present with late hypertension. Increased gene expression of aortic wall collagen and vascular smooth muscle cell markers occurs in the presence of hypertension. Before repair, a patent ductus arteriosus (PDA) limits hypertension proximal to the coarctation. We hypothesize that preoperative collagen and vascular smooth muscle expression from the aortic arch in children is variable, depending on the presence or absence of a PDA. We analyzed the expression patterns of collagen and vascular smooth muscle cell markers in 25 children with CoA using a quantitative polymerase chain reaction. Aortic arch tissue proximal to the CoA was normalized to descending aortic tissue distal to the coarctation. Collagen-I, transforming growth factor-β, elastin, and calponin were analyzed. At repair, 19 patients were aged younger than 3 months (14 with a PDA, 5 with a ligamentum arteriosum), and the remaining 6 were older than 1 year. There was no difference in age or weight between infants with or without a PDA. Infants without a PDA had the greatest difference in collagen-I expression compared with infants with a PDA (7.0 ± 1.6-fold vs 0.8 ± 1.1-fold, p = 0.01). Expression of transforming growth factor-β (4.3 ± 1.4 vs 2.6 ± 2.3, p = 0.01) and calponin (3.7 ± 0.7 vs 0.6 ± 1.1, p = 0.05) was lower from infants with vs without a PDA. Our findings provide evidence of preoperative changes in the aortic arch before repair, particularly in the absence of a PDA.

CARDIOTROPHIN-1 IS A DETERMINANT OF ARTERIAL STIFFNESS AND THICKNESS IN RODENTS: 3A.03

Background and Aims: Besides its known cardiac effects, cardiotrophin-1 (CT-1), a cytokine belonging to the interleukin-6 family, exerts proliferative and secretory effects in vascular smooth muscle cells. We aimed to investigate the functional and morphological vascular changes induced by chronic CT-1 administration in rats and its involvement in the arterial phenotype of CT-1-null mice in vivo. Methods: A) Recombinant rat CT-1 (20 μg/Kg, IP) was administrated to Wistar rats for six weeks (n = 10/group). Blood pressure (BP) and heart rate were recorded by telemetry. Cardiac function was assessed using PET-scan. B) 2 year-old wild-type (WT) (n = 8) and CT-1-null mice (n = 3) were studied. Vascular structure and function were evaluated by an echo-tracking device. Circumferential wall stress, incremental elastic modulus (Einc), media cross-sectional area and pulse wave velocity (PWV) were measured. Aortic wall collagen and elastin contents were determined using immunohistochemistry, and the expression of collagen type I and III, elastin and fibronectin was quantified by RT-PCR and Western blot in aortic extracts. Results: A) Neither vehicle nor CT-1 treatment modified BP. CT-1-treated rats displayed decreased cardiac output (p < 0.01) as well as wall stress (p < 0.01), Einc (p < 0.01) and PWV (p < 0.05) as compared with vehicle group. CT-1-treated rats also showed increased media cross sectional area (p < 0.01) and collagen content (p < 0.01). CT-1-overloaded rats displayed increased expression of collagen type I (p < 0.05) and III (p < 0.01) and fibronectin (p < 0.01). B) CT-1-null mice presented an increased wall stress (p < 0.05) and Einc (p < 0.05) as compared with WT mice. Media cross sectional area and collagen content were reduced (p < 0.05) in mice lacking CT-1. Conclusions: Normotensive rats subjected to CT-1 overloading developed impaired cardiac and vascular functions, characterized by an increment in arterial stiffness accompanied by an augmented media thickness and extracellular matrix production. Accordingly, CT-1-null mice presented a reduced arterial stiffness and a reduced media thickness and collagen content. Our data show that CT-1 is a key player in arterial thickness and stiffness and in the cardiovascular coupling.

Synergistic effect of angiotensin II and nitric oxide synthase inhibitor in increasing aortic stiffness in mice

Although they are implicated on their own as risk factors for cardiovascular disease, the potential link between nitric oxide (NO) deficiency, ANG II, and vascular stiffening has not been tested before. We evaluated the role of chronic ANG II treatment and NO deficiency, alone and in combination, on aortic stiffness in mice and tested parameters contributing to increases in active or passive components of vascular stiffness, including blood pressure, vascular smooth muscle contractility, and extracellular matrix components. Untreated (control) mice and mice treated with a NO synthase (NOS) inhibitor [N(omega)-nitro-L-arginine methyl ester (L-NAME), 0.5 g/l] were implanted with osmotic minipumps delivering ANG II (500 ng.kg(-1).min(-1)) for 28 days. Aortic stiffness was then measured in vivo by pulse wave velocity (PWV) and ex vivo by load-strain analysis to obtain values of maximal passive stiffness (MPS). Blood pressure and aortic contractility ex vivo were measured. ANG II treatment or NOS inhibition with L-NAME did not independently increase vascular stiffness; however, the combined treatments worked synergistically to increase PWV and MPS. The combined treatments of ANG II + L-NAME also significantly increased aortic wall collagen content while decreasing elastin. These novel results suggest that NO deficiency and ANG II act synergistically to increase aortic stiffness in mice predominantly via changes in aortic wall collagen/elastin ratio.

Improvement of aortic wall distensibility and reduction of oxidative stress by pioglitazone in pre-diabetic stage of Otsuka Long-Evans Tokushima fatty rats.

We tested the hypothesis that pioglitazone (insulin sensitizer) reduces oxidative stress and improves aortic wall distensibility in the pre-diabetic stage of Otsuka Long-Evans Tokushima Fatty rats, type 2 diabetes mellitus (DM) model. 20 DM and 9 nonDM male rats were divided into 3 groups: treated-DM, untreated-DM, and untreated-nonDM. Pioglitazone (0.01%) was mixed in chow in the treated group from 15 to 20 weeks of age. At baseline and 20 weeks, plasma malondialdehyde (MDA) was measured. At 20 weeks, intravascular ultrasound images and aortic pressure were simultaneously recorded. Stiffness parameter beta was calculated from the cyclic variations of aortic diameter and pressure. From an excised thoracic aorta, aortic wall collagen was measured, and the morphology was histopathologically evaluated by hematoxylin-eosin staining. At 20 weeks, MDA (nmol/ml) in treated-DM (2.3 +/- 0.3) was lower than in untreated-DM (3.2 +/- 0.6, p < 0.0001). beta in treated-DM (0.53 +/- 0.21) was smaller than that in untreated-DM (0.88 +/- 0.26, p = 0.0067). Aortic wall collagen (mg/100 mg dry weight) did not decrease in treated-DM (22.3 +/- 3.2 vs untreated-DM : 19.6 +/- 4.7). Lumen/medial area ratio (L/M) increased in treated-DM (2.79 +/- 0.40 vs untreated-DM : 2.22 +/- 0.20, p = 0.0041, untreated-nonDM : 2.25 +/- 0.55, p = 0.0075). MDA was significantly correlated with beta (r = 0.65, p = 0.0005) or L/M (r = -0.60, p = 0.0008). Pioglitazone may reduce oxidative stress and contribute to improvement of aortic wall stiffness without decrease in collagen content at an early prediabetic stage of type 2 DM.

Viscoelasticity of the vessel wall: the role of collagen and elastic fibers.

The aortic wall contains collagen fibrils, smooth muscle cells, and elastic fibers as the primary load-bearing components. It is well known that the collagen fibrils bear loads in the circumferential direction, whereas elastic fibers provide longitudinal as well as circumferential support. Stiffening of the vessel wall is associated with loss of elastic tissue and increases in the collagen content: however, little is known about the mechanism of vessel wall stiffening with age. The purpose of this review is to attempt to relate structural changes that occur to the collagen and elastic fibers to changes in the viscoelastic behavior that are associated with aging. Analysis of the viscoelastic mechanical properties of collagen fibrils from tendon, skin, and aortic wall suggest that the collagen fibrils of aortic wall are different than those of other tissues. The elastic spring constant of the collacen fibrils in vessel walls is significantly less than that found in tendon, suggesting that the presence of type III collagen in aortic wall increases the flexibility of the collagen fibrils. Furthermore, it is hypothesized that changes in the interface between collagen fibrils, elastic fibers, and smooth muscle during aging and in connective tissue disorders leads to changes in the viscoelasticity of the vessel wall.

Effects of troglitazone on collagen accumulation and distensibility of aortic wall in prestage of non-insulin-dependent diabetes mellitus of Otsuka Long-Evans Tokushima Fatty rats.

We investigated the effect of troglitazone (TG) on aortic distensibility and histopathology at the preclinical stage in the non-insulin-dependent diabetes mellitus (NIDDM) model. Twenty male diabetic and 20 male nondiabetic rats were each divided into two groups: treated-DM, untreated-DM, treated-nonDM, and untreated-nonDM. TG (0.2%) was mixed in chow in the treated groups. From age 5 to 15 weeks, fast blood glucose and insulin were monitored. At 15 weeks, oral glucose tolerance test results, aortic wall histopathology, and collagen content were studied, and intravascular ultrasound images and aortic pressure were recorded. Aortic diameter was measured during the cardiac cycle, and the stiffness parameter beta was calculated. Blood glucose (mg/dl) 2 h after loading in treated-DM (139+/-20) was normalized (untreated-DM, 188+/-27; p<0.05). Insulin concentration (ng/ml) in treated-DM (3.2+/-0.4) was lower than that in untreated-DM (8.1+/-1.5; p<0.01). At 15 weeks, beta in untreated-DM (2.4+/-0.8) was larger than those in untreated-nonDM (1.5+/-0.4; p<0.0001) and in treated-DM (1.9+/-0.4, p = 0.0081). Aortic wall collagen (mg/g dry weight) increased in untreated-DM (32.8+/-3.3) as compared with treated-DM (28.1+/-3.8; p = 0.048). Histomorphometry showed decreased medial area (mm2) in treated-DM (0.55+/-0.05) compared with untreated-DM (0.78+/-0.12; p<0.0001). This study suggests that TG may prevent metabolic abnormalities and the deterioration of aortic distensibility at an early prediabetic stage.