Histopathology of aortic media tunica and plasma oxidative stress assessment during testosterone deficiency in male rats

Sexual hormones are determinant players in cardiovascular diseases. The aim of this study was to investigate the effects of testosterone deficiency, induced by castration, on oxidative status and the histopathology of the aor-tic media tunica. The experiments were undertaken on a batch of 30 Wistar males’ rats randomised into 3 groups, 10 control (Con), 10 castrated (Cas) and 10 castrated then supplemented with testosterone (Cas-T). Our results showed that testosterone deficiency induced a significant decrease in myeloperoxidase activity (19,95 ± 1, 79 vs 34,86 ± 1,13, p˂0,0001) this was maintained even after testosterone replacement. Furthermore, testosterone deficiency decreased the antioxidant capacity by reducing GSH in plasma (0,118 ± 0,003 vs 0,15 ± 0,011, p˂0,05). Our results also indicate that testos-terone supplementation leads to a significant increase in ceruloplasmin lev-els (62,37 ± 15,89 vs 148,12 ± 27,77, p ˂0.05). The histomorphometric exami-nation of the aortic tunica media in castrated rats showed a significant de-crease of media thickness (274,7 ± 2,96 vs 317,6 ± 5,19, p ˂0.0001) and VSMC count (108,1 ± 6,47 vs 130 ± 6,147, p ˂ 0.05) associated with damaged and broken elastic lamina. Testosterone supplementation restores the media thickness and the count of VSMC. Our findings demonstrate that testos-terone deficiency leads to a decrease in the count of VSMC and a rupture of elastic lamina. Testosterone altered the plasma oxidative status through ac-tions on GSH, MPO and ceruloplasmin.

Transcriptome and N6-Methyladenosine RNA Methylome Analyses in Aortic Dissection and Normal Human Aorta

Objective: To investigate the N6-methyladenosine (m6A) modification and the expressions of the m6A regulatory genes in the acute aortic dissection (AD).Methods: MeRIP-seq and RNA-seq experiments of aortic media tissue samples obtained from AD (n = 4) and Controls (n = 4) were conducted. m6A methylation quantification was used to measure the total mRNA m6A level. The five m6A regulators mRNA expressions were analyzed by quantitative polymerase chain reaction (qPCR). Western blot analyses and immunofluorescence staining were used to detect the difference of METTL14 protein expression in the aortas of AD and Normal.Results: Among AD patients, we detected significantly elevated levels of m6A in total RNA. Compared with the normal group, the up methylated coding genes of AD were primarily enriched in the processes associated with extracellular fibril organization, while the genes with down methylation were enriched in the processes associated with cell death regulation. Furthermore, many differentially methylated m6A sites (DMMSs) coding proteins were mainly annotated during the extracellular matrix and inflammatory responses.Conclusions: These findings indicate that differential m6A methylation and m6A regulatory genes, including MTEEL14 and FTO, may act on functional genes through RNA modification, thereby regulating the pathogenesis of aortic dissection.

Outcomes of Ruptured Sinus of Valsalva Aneurysm -A 20-year experience

Background: Ruptured aneurysms of sinus of Valsalva are defects of the aortic media, which are uncommon yet present concomitantly with either ventricular septal defect, aortic insufficiency or both. Here, we analyse retrospectively outcomes of patients operated on in the last two decades. Patients and Methods: 151 cases of ruptured aneurysms of sinuses of Valsalva were treated here between January 2000 and December 2020. The majority (96%) arose from the right coronary sinus. The right ventricular outflow was the most common site of rupture (56.2%). Ventricular septal defect was associated in 24 patients (16%) all of whom had ruptured right sinus, of which 8 (33%) were of subpulmonic subtype. Aortic incompetence was found in 45 patients (43.3%). Elective surgery was offered to 78 patients (51.6%), while the rest had defects closed by interventional devices. Surgical conversion for device embolization occurred in 12 patients (7.94 %). The defect was closed through the aortic root in 13 patients (14.4% of 90) and employing the bicameral technique (root and ruptured chamber) in the remaining 87 patients. 18 patients (20%) underwent aortic valve repair while 5 (5.5%) underwent aortic valve replacement. Results: We had no hospital deaths, however 4 operated patients (2.6%) had comorbidities. Follow‐up ranged from 1 to 20 years (mean 13 ± 5). There were 3 deaths in this period, and among the majority, quality of life was uneventful. Conclusion: Surgical correction for ruptured aneurysms of Valsalva provides prudent results and must be the preferred modality of treatment in acute and chronic presentation.

Protective effects of astragaloside IV against hypertension-induced vascular remodeling involves the DNMT1 and TET2 signaling pathway

Proliferation, migration, and the phenotypic switch of vascular smooth muscle cells (VSMCs) play an important role in vascular remodeling induced by hypertension. Astragaloside IV (AS-IV), the active ingredient of Astragalus membranaceus, has been shown to exert a beneficial role in cardiovascular disease. The present study aimed to investigate the mechanism responsible for the protective effects of AS-IV on hypertension-induced vascular remodeling. AS-IV significantly reduced blood pressure and aortic media thickness in two-kidney, one-clip (2K1C) hypertensive rats. AS-IV administration downregulated the expression levels of DNA methyltransferase1 (DNMT1), matrix metalloproteinase (MMP2) and proliferating cell nuclear antigen (PCNA) and upregulated the expression of smooth muscle 22? protein (SM22?), ?-smooth muscle actin (ACTA2) and ten-eleven translocation 2 (TET2) in the aorta of hypertensive rats. AS-IV inhibited the proliferation and migration in VSMCs treated with angiotensin II (Ang II). AS-IV increased the expression of SM22?, ACTA2 and TET2, and decreased the expression of collagen Ia (COL-1a), collagen IIIa (COL-3a), DNMT1, MMP2 and PCNA in vitro. Reduction in 5-methylcytosine (5-mC) was observed in VSMCs treated with AS-IV. Knockdown of DNMT1 induced the expression of TET2, while the level of DNMT1 did not change after knockdown of TET2. These results suggest that AS-IV reversed hypertension-induced vascular remodeling by inhibiting DNMT1 and upregulating TET2.

Regional and Layer Distribution of Residual Stresses in an Unloaded Aortic Medial Wall

The mechanical and structural characteristics of aortic media have profound effects on the physiology and pathophysiology of an aorta. However, many aspects of the aortic tissue remain poorly understood, partly due to the intrinsic layered wall structure and regionally varying residual stresses. Our recent works have demonstrated that a mechanical interaction between the elastic lamina (EL) and smooth muscle layer in the aortic media can be computationally reproduced using a simplified finite element (FE) model. However, it is questionable whether the simplified FE model we created was representative of the structure of a real medial wall and its modeling technique would be applicable to develop a more sophisticated and structure-based aortic FE model. This study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state and successfully reproduced transmural variation in EL waviness across the aortic wall. We also aimed at confirming the inner and outer layers of the medial wall are subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. Moreover, the computed residual stresses were found to be within the reasonable range of the predicted values, 1–10 kPa, supporting the validity of our modeling approach. Although further study is required, the information obtained here will greatly help improve the understanding of basic aortic physiology and pathophysiology, while simultaneously providing a basis for more sophisticated computational modeling of the aorta.

Abstract P078: Sex Differences In Aortic Stiffness Following Simulated Microgravity In Middle Aged Rats

Men and women have different cardiovascular responses to spaceflight. We determined sex differences in arterial stiffness, an independent risk factor for cardiovascular dysfunction, in rats after the exposure to 14-days of simulated weightlessness via hindlimb unloading (HLU). Male and female Sprague-Dawley rats at 20 weeks of age were either tail suspended via HLU or remained full-weight bearing in similar cages. Female control rats had lower body weight compared with males. There was no significant effect of HLU on body weight in either male or female rats. Our data demonstrate that HLU increased aortic pulse wave velocity, an index of arterial stiffness, in female rats (2.7 fold vs. control female- adjusted for body weight, n=5-6), but not in males. HLU had no effect on the levels of structural proteins (alpha smooth muscle actin or myosin) in either female or male rats. The levels of G-protein-coupled estrogen receptor 1 (GPER) were lower in the thoracic aorta of female rats exposed to HLU compared with female controls (0.3±0.02 vs. 0.39±0.01 relative density, p<0.05, n=6-7); lower aortic GPER levels were associated with greater aortic media thickness (110.5±4.2 vs. 97.1±3.1 μm, p<0.05, n=5) and lower COX-2 protein levels (0.47±0.04 vs. 0.61±0.02 relative density, p<0.05, n=3-4). However, no differences in GPER, aortic media thickness, or COX-2 were observed in the aortas of male rats after HLU versus male controls. The administration of GPER agonist, G1 (400 ug/kg/day) prevented the increase in aortic pulse wave velocity in the intact females following HLU (2.2±0.2 vs. 9.7±1.8, p<0.05, n=4). Our data demonstrate sex differences in aortic stiffness in response to simulated microgravity. Since GPER has many protective actions in the cardiovascular system, a dysregulation of estrogen signaling may attenuate the protection of females from cardiovascular dysfunction following the exposure to spaceflight stressors.

Long-term adaptive versus maladaptive remodelling of the pulmonary autograft after the Ross operation

OBJECTIVES Following the Ross operation, the pulmonary autograft undergoes structural changes (remodelling). We sought to determine the extent, nature and possible determinants of long-term remodelling in the different components of the pulmonary autograft. METHODS Ten pulmonary autografts and 12 normal control valves (6 pulmonary and 6 aortic) were examined by conventional histology, immunocytochemistry and electron microscopy. The structural changes were quantified by morphometry. RESULTS The leaflets from free-standing root replacement valves demonstrated thickening to levels comparable to the normal aortic leaflets, largely due to the addition of a thin layer of ‘neointima’ formed of radial elastic fibres, collagen bundles and glycoaminoglycans, on the ventricular aspect of the leaflets. The leaflets of valves from sub-coronary implantation demonstrated a significantly thicker fibroelastic layer on the ventricularis and calcium deposition in the fibrosa. The media of the explanted valves showed increased number of lamellar units to levels comparable to normal aortic roots. Electron microscopy of valves inserted as free-standing roots showed increased organization into continuous layers. However, intralamellar components showed varying degrees of ‘disorganization’ in comparison to those in the normal aortic media. In addition, there was a marked increase in the number of vasa vasorum with thickened arteriolar wall in the outer media and adventitia. CONCLUSIONS Following the Ross operation, in the very long term, all components of the autograft showed varying degrees of remodelling, which was judged to be largely adaptive. Defining the type, determinants and possible functional effects of remodelling could help in understanding and optimizing the results of the Ross operation.