Aortic Stiffness Research Articles

Losartan and metabolite EXP3179 activate endothelial function without lowering blood pressure in AT2 receptor KO mice

BackgroundWe have documented profound release of nitric oxide (NO) and endothelium-derived hyperpolarization factor (EDHF) by angiotensin II (ANGII) receptor 1 (AT1) blocker (ARB) losartan and its unique metabolite EXP3179, a pleiotropic effect that may help rationalize the protective properties of ARBs. Since blood pressure (BP) lowering by ARBs likely require an ANGII-dependent switch from AT1 to ANGII receptor 2 (AT2) signaling, a receptor known to stimulate endothelial NO release, we investigated the contribution of AT1 and AT2 to losartan and EXP3179’s endothelial function-activating properties. Experimental ApproachTwo AT1 ligands were used in an attempt to block the AT1-dependent endothelium-enhancing effects of EXP3179. AT2-null mice were used to evaluate the acute ex vivo and chronic in vivo effects of EXP3179 (20μM) and losartan (0.6 g/l), respectively, on endothelial function, BP and aortic stiffness. Key resultsEx vivo blockade of AT1 receptors did not attenuate EXP3179’s effects on NO and EDHF-dependent endothelial function activation. We observed significant reductions in PE-induced contractility with EXP3179 in both WT and AT2 knockout (KO) aortic rings. In vivo, a 1-month chronic treatment with losartan did not affect pulse wave velocity (PWV) but decreased PE-induced contraction by 74.9 % in WT (p < 0.0001) and 47.3 % in AT2 KO (p < 0.05). Presence of AT2 was critical to losartan’s BP lowering activity. ConclusionIn contrast to BP lowering, the endothelial function-enhancing effects of losartan and EXP3179 are mostly independent of the classic ANGII/AT1/AT2 pathway, which sheds light on ARB pleiotropism.

T cell specific Eomes Deletion Does Not Protect Against High Fat Diet Induced Large Artery Stiffening

We have found that T cells contribute to age-related large artery stiffness. The T-box transcription factor, Eomes is an important regulator of CD8+ (Cytotoxic) T cell differentiation from a naïve to a memory phenotype. We previously reported that these effector memory CD8+ T cells accumulate in the aorta of old mice. We aimed to investigate whether inhibiting CD8+ T cell memory differentiation in mice, specifically through T cell-specific Eomes deletion, would protect these animals from high-fat diet (HFD)-induced large artery stiffness. Mice with a CD8 driven Cre Recombinase were bred with mice with loxp sites surrounding the Eomes gene resulting in wild type (CD8 Eomes+/+) and T cell specific Eomes deleted (CD8 Eomesf/f) mice. Mice were randomly divided into a normal chow (NC) and HFD. Resulting in 8 mice of each genotype and diet. The NC group was given a normal diet containing 4% fat and the HFD group was given a high-fat diet containing 60% fat. At 4-8 months of age, doppler pulse wave velocity was used to assess large artery stiffness. Following euthanasia, aortic T cell phenotype was assessed using flow-cytometry. Group differences were assessed by two-way ANOVA and Tukey’s post-hoc test. Data shown as mean ± SD. Regardless of genotype, HFD had a significant impact on pulse wave velocity (PWV), indicating elevated aortic stiffness. In the HFD group, both CD8 Eomesf/f and CD8 Eomes+/+ mice exhibited higher PWV values (330.08±72.33 cm/s;312.5±53.74 cm/s) compared to their counterparts in the NC group (256.4±63.67 cm/s;259.2±66.36 cm/s, p=0.0172). To determine whether HFD-induced increases in aortic stiffness are accompanied by changes in aortic T cell phenotype, flow cytometric analysis was performed on the aorta. First, we observed, regardless of mouse genotype, HFD had a significant impact on CD4+ (Helper T) naïve cells, resulting in a blunted percentage of these cells. This dietary effect was observed in both CD8 Eomesf/f and CD8 Eomes+/+ mice (NCD CD8 Eomesf/f: 70.92±5.912%; NCD CD8 Eomes+/+ mice: 56.46±20.62%; HFD CD8 Eomesf/f: 47.5±7.865%; HFD CD8 Eomes+/+ mice: 50.58±13.907%; p=0.0206). In contrast, the percentages of CD8+ naïve cells did not display a significant change in response to the high-fat diet (p=0.6303). HFD significantly influenced CD4+ memory cells, resulting in an increase in percentages, regardless of mouse genotype (NCD CD8 Eomesf/f: 29.09± 5.909%; NCD CD8 Eomes+/+ mice: 44.27±19.17%; HFD CD8 Eomesf/f: 52.47±7.875%; HFD CD8 Eomes+/+ mice: 49.44±13.9%; p=0.02). However, HFD did not produce any significant alterations in CD8+ memory cell percentages (p=0.6). These results suggest that contrary to our hypothesis, T cell specific Eomes deletion is not suffcient to protect against diet induced large artery stiffness. However, this may be due to greater proportions of CD4+ memory cells in the aorta with high fat feeding. Funding: AHA 940023, NIH R01AG060395, K01AG061271. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

EVALUATION OF CARDIOVASCULAR RISK FACTORS IN CHILDREN AGED 6-16 YEARS OLD AND THEIR EVOLUTION AT EARLY ADULTHOOD IN A 10-YEAR FOLLOW UP STUDY

Objective: Objective: Obesity and arterial hypertension in children represent well recognized main risk factors for cardiovascular (CV) events during adult life. We aimed to investigate any changes regarding several CV risk (CVR) factors of children aged 6-16 years old after a 10-year follow-up period. Design and method: Design and method: A cohort of 143 healthy children 6-16 years old (79/64 boys/girls, aged 9±2 years) was initially evaluated regarding CVR factors [obesity, blood pressure (BP), aortic stiffness, lipid profile] plus food habits/sports activity. At 10-years follow-up, 62/143 (43%) young adults were re-evaluated (33/31 boys/girls, aged 20±2 years old). Results: Results: Obesity, found in 45% of children, was accompanied by increased BP (p&lt;0.001) and a less favorable low density lipoprotein cholesterol (LDL-C)/triglycerides profile (p=0.001). In a 10-year follow-up, obesity and exercise improved (p&lt;0.001 and p=0.005), BP was elevated (p&lt;0.001) at levels of high normal (40% of young adults), aortic stiffness increased (p&lt;0.001), LDL-C and high density lipoprotein cholesterol (HDL-C) decreased (p=0.004 and p&lt;0.001), triglycerides increased (p=0.04), and food approached the western model of nutrition (less fish/fruits). In children and young adults, body mass index (BMI) was associated with age (Beta=0.47, p&lt;0.001 and Beta=0.36, p=0.004), systolic BP (Beta=0.46 and Beta=0.52, p&lt;0.001), and LDL-C (Beta=0.27 and Beta=0.44, p&lt;0.001). Conclusions: Conclusions: An increased incidence of obesity associated with systolic BP and accompanied by a less favorable lipid profile was found in children. At 10-years re-evaluation, obesity was partly improved, systolic BP had reached the high-normal levels in a substantial number of young adults while lipid profile was less favorable compared to baseline evaluation. Our results highlight the evolution of CVR factors from childhood to early adulthood.

Abstract 1110: The Sex-specific Role Of The Mineralocorticoid Receptor In Smooth Muscle Cells In Obesity-associated Vascular Stiffness

Introduction: Obesity is associated with increased vascular stiffness which predicts risk for heart attack, stroke and cardiovascular (CV) mortality. Obesity is more common and has a greater negative impact on CV health in women. Perivascular adipose tissue (PVAT), which contributes to maintenance of normal vascular tone, becomes dysfunctional in obesity, but its role in vascular stiffness is less well studied. Mineralocorticoid receptor (MR) is a hormone-activated transcription factor regulated by inflammation and oxidative stress in aging vascular smooth muscle cells (SMC) where it induces vascular stiffness. The role of SMC-MR in obesity-associated vascular stiffness and whether there are sex differences in the mechanism is unknown. Hypothesis: We hypothesized that sex differences in obesity-induced changes in PVAT alters aortic inflammation and oxidative stress (OS) to induce SMC MR and contribute to aortic stiffness by regulating sexually dimorphic gene programs. Methods and Results: Young male and female mice (3 months old) with MR intact or SMC-MR knocked out (SMC-MR-KO) were fed with high-fat diet (HFD) for 3 months. In both sexes, MR mRNA expression increased with obesity in MR intact mice, as did aortic stiffness (by pulse wave velocity (PWV)). SMC-MR-KO prevented the HFD-induced vascular stiffness in both sexes. In aortas from male mice only, NFkB protein were induced by obesity, independent of the MR. Obese males had increased vascular fibrosis histologically, vascular fibrosis gene (Col1, CTGF) expression and inflammation (TNFa, IL1B) in MR intact mice and is prevented in the SMC-MR-KO mice. In females, HIF1a protein and mRNA were induced by obesity, independent of SMC MR. In MR-intact females, OS gene expression (NADPH-oxidase 2-4 (Nox2, Nox4)) was increased by HFD. Human aortic SMC (HASMCs) from lean/obese male and female donors were cultured. NFkB, MR, and Col1 were increased with obesity in HASMCs from males while HIF1a, MR, Nox2 and Nox4 were increased in obese female donors compared with non-obese. Conclusions: These data support sexually dimorphic, SMC MR-dependent mechanisms for vascular stiffness associated with obesity and suggest that sex-specific therapies may be needed to prevent obesity-associated vascular stiffness.

Severity and frequency of menopausal hot flash symptoms are not associated with arterial stiffness in females

Background: Females who experience menopausal hot flashes ([MHF]; episodes of sudden warmth and sweating) have greater risk of developing hypertension than females without MHF. MHF symptom severity and frequency are positively associated with hypertension. Considering that augmented arterial stiffness contributes to hypertension, this work aimed to investigate the relations between MHF severity and frequency with arterial stiffness. We hypothesized that females with moderate to severe MHF symptoms would exhibit greater arterial stiffness compared to females without MHF symptoms. Further, we hypothesized that there would be a positive relation between MHF frequency and arterial stiffness. Methods: Twenty-five females (51±5 [SD] years) with no history of hypertension or cardiovascular disease participated. The Menopausal Rating Scale was used to categorize participants by symptom severity (None MHF: n=7, Mild MHF: n=9, Moderate/Severe MHF: n=9). Participants self-reported MHF frequency over three consecutive days in real time using a hot flash diary (4±5 MHF/day, Range: 0-16). After 15 minutes of supine rest, brachial cuff blood pressures (sphygmomanometer) and heart rate (electrocardiogram) were recorded. Arterial stiffness was measured as pulse wave velocity ([PWV]; SphygmoCor®). PWV was measured using a carotid tonometer simultaneously with a leg cuff to capture blood pressure waveforms at the carotid and femoral sites. Aortic systolic pressure, aortic diastolic pressure, and augmentation index (AIx) were measured via pulse wave analysis ([PWA]; SphygmoCor®) using a brachial cuff. Data were analyzed using one-way analysis of variance (ANOVA) and Spearman Rho (ρ). Results: Age, body mass index, resting mean blood pressure, and resting heart rate were not different among MHF severity groups (P&gt;0.05 for all). PWV was not different among severity groups (None: 6.2±0.67 vs. Mild: 6.4±1.0 vs. Moderate/Severe: 6.6±1.0 cm/s, P=0.72). MHF frequency did not correlate with PWV (P=0.42). Aortic systolic pressure (None: 110±6 vs. Mild: 114±5 vs. Moderate/Severe: 112±11 mmHg, P=0.66), aortic diastolic pressure (None: 76±9 vs. Mild: 77±6 vs. Moderate/Severe: 76±10 mmHg, P=0.93), and AIx (None: 31.9±9.0 vs. Mild: 38.7±11.1 vs. Moderate/Severe: 30.4±7.4 %, P=0.16) were not different among severity groups. MHF frequency did not correlate with metrics of PWA (Systolic: P=0.61; Diastolic: P=0.89, AIx: P=0.42). Conclusion: Arterial stiffness and metrics of PWA were not different among females with varying MHF symptom severity. MHF frequency was also not correlated with aortic stiffness and metrics of PWA. Other mechanisms of vascular function (e.g., autonomic function, vasodilation, and/or vasoconstriction) should be investigated to determine potential contributors of hypertension risk in females with MHF. AHA 898649, NIH T32 DK07352, K01 HL148144, NCATS UL1 TR002377. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Streptococcus pneumoniae infection promotes the long-term development of an atherosclerotic phenotype in atheroprone ApoE-deficient mice

Background: Epidemiological studies have identified pneumonia to be closely linked to an increased risk for cardiovascular events. Potential causality of this association, however, remains to be established, and underlying mechanisms are yet to be resolved. Here, we tested the hypothesis that prior pulmonary infection with Streptococcus pneumoniae accelerates the development of an atherosclerotic phenotype in mice. Such a phenotype would explain the increased cardiovascular risk in the epidemiological data. Methods: Atheroprone ApoE−/− mice were fed a high fat diet, and after 6 weeks nasally infected with either 2.5 x 107 S. pneumoniae or vehicle control. Antibiotic therapy was initiated 60h post infection (p.i.) by s.c. injections of ampicillin on 5 consecutive days followed by oral administration of amoxicillin for 10 days. At days 35 or 90 post-infection, aortas were harvested and assessed for vasoreactivity and arterial stiffness by wire myography. Morphological changes of the aortic vessel wall and eNOS expression levels were quantified by western blot and histological stainings. Results: Unexpectedly, 35 days p.i. aortas of infected mice presented with decreased aortic stiffness, increased endothelial-independent vasorelaxation and decreased wall thickness due to lower collagen-1 expression and reduced elastin fragmentation when compared to sham animals. After 90 days, however, these effects had reversed and animals with prior pneumonia showed increased aortic stiffness, attenuated endothelial dependent vasorelaxation that was associated with reduced eNOS protein expression and phosphorylation, and increased atherosclerotic plaque burden relative to vehicle control. Conclusion: Single episodes of pneumonia promote a delayed pro-atherogenic phenotype that manifests as endothelial dysfunction, aortic stiffening and enhanced plaque burden. Underlying mechanisms are currently under investigation to identify risk predictors for patient stratification and clinical targets for prevention of cardiovascular disease following pneumonia. Funding: German Ministry of Education and Research (BMBF) in the framework of SYMPATH (01ZX1906A). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

PRECLINICAL VASCULAR ORGAN DAMAGE AND VASCULAR AGEING ASSESMENT IN NON-ALCOHOLIC FATTY LIVER DISEASE AND METABOLIC ASSOCIATED FATTY LIVER DISEASE PATIENTS

Objective: Non-alcoholic fatty liver disease (NAFLD) and metabolic associated fatty liver disease (MAFLD) are a growing health problem, with a growing prevalence due to its association with metabolic syndrome and diabetes. It is known to be a risk factor for the development of cirrhosis and hepatocarcinoma, but it is also known to be an important cardiovascular risk factor. The aim of this study is to assess the burden of preclinical vascular organ damage. Design and method: The study enrolled 80 consecutive patients (mean age 63.3±15.0) who underwent hepatological evaluation in our department, with evaluation of liver fibrosis score (APRI score, FIB-4) and liver stiffness, and quantification of cardiovascular risk according to Guidelines (2021 ESC Guidelines on cardiovascular disease prevention in clinical practice). Carotid atherosclerotic burden was evaluated by B-mode ultrasound in each segment (common, bulb, internal), bilaterally, and expressed as mean of maximum IMT (M-MAX), right common carotid artery distensibility and stiffness (CardioVascular Suite 4, Quipu, Italy). Aortic stiffness was evaluated as carotid-femoral pulse wave velocity (PWV), measured by applanation tonometry (PulsePen DiaTecne, Italy), with calculation of vascular ageing. Results: We found no significant correlation between ultrasound or tonometry parameters and liver stiffness and fibrosis scores. VPWV was significantly above upper limit of normal of 10 m/s (11.6±6.0 m/s, p=0.02), and the percentiles for age were significantly higher than 50th (61.7±25.1, p&lt;0.001), with 52,5% of patients showing increased PWV. Similarly, M-MAX was higher than the upper normality level of 0.9 mm (1.09±0.30 mm, p&lt;0.001). 70% of patients had an increased M-MAX. Vascular age based on arterial stiffness resulted significantly higher than biological age (mean difference 4.6 years, p&lt;0.001). 76.2% (71/80) of the overall cohort and 45,2% (14/31) of patients classified as low risk showed at least one type of vascular organ damage. Conclusions: Patients with NAFLD or MAFLD showed a large prevalence of arterial stiffening and increased IMT and an enhanced vascular ageing, even among those classified at low cardiovascular risk according to Guidelines. Vascular organ damage evaluation could be useful to identify preclinical organ damage in these patients

Abstract 3065: Biomechanical Forces Can Promote SGK-1-dependent Expression Of Pathologic Matrix Markers

Introduction: Hypertension is a known predictor of cardiovascular morbidity due to dysfunctional matrix remodeling which promotes aortic stiffness, but achieving normotension does not eliminate this risk. Prior work has demonstrated mechanical sensitivity of the serum and glucocorticoid inducible kinase-1 (SGK-1) in vascular disease through inflammatory signaling. We hypothesize that biomechanical signals promote activity of SGK-1 in VSMCs to drive expression of key pathologic matrix markers (PMMs). Methods: Aortic rings were harvested from C57BI/6 WT and smooth muscle specific SGK-1 knockout (SMC-SGK-1KO +/- ) mice. Rings were placed on a myograph in a physiologic salt solution and exposed to experimentally derived optimal tension (baseline OT, 1.5g) or OT+30% (1.95g) for 6 hrs (n=4-6). WT Rings were homogenized to determine SGK-1 and pSGK-1 abundance by immunoblotting. Replicates were treated ±AngII and ±EMD638683 (EMD; a specific SGK-1 inhibitor). RNA extraction enabled QPCR for select PMMs (Interleukin-6 (IL-6), Cathepsin S (CtsS), Cystatin C (CysC), Tenascin C (TNC)). Statistical comparisons utilized ANOVA with significance set at p&lt;0.05. Results: There was a significant increase in pSGK-1 abundance and in the pSGK-1/SGK-1 ratio in the WT aortic rings at OT+30%, confirming that mechanical tension promoted SGK-1 activity. IL-6 and CysC expression was augmented in the WT OT+30% (p&lt;0.05 vs WT OT for each), but returned to baseline in the presence of EMD, implicating that SGK-1 may play a causative role for these effects. While expression of all PMMs increased with OT+AngII or OT+30%+AngII, only IL-6 demonstrated a synergistic effect with biomechanical stimulation. In aortic rings from SMC-SGK-1KO +/- animals, the response to mechanical stimulation was blunted for all PMMs, further supporting a role for SGK-1 in pathologic mechanical signaling. Conclusion: Mechanical tension on the aortic wall can increase SGK-1 activity, correlating to expression of key mediators of pathologic vascular remodeling. These novel findings suggest that SGK-1 may be a druggable target to reduce aortic stiffness in the setting of hypertensive disease.

Abstract 3004: Intermittent Hypoxia Decreases Aortic Stiffness And Facilitates Abdominal Aortic Aneurysm

Introduction: Intermittent hypoxia (IH) is a phenomenon observed with obstructive sleep apnea (OSA), which is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, it remains unknown if IH is a risk factor for the development of AAA. The goal of this study was to determine the effects of IH exposure on arterial stiffness, and to assess whether IH increases the susceptibility to angiotensin (Ang) II-induced AAA in mice. Methods: Male C57BL/6 mice (8-week-old) were subjected to IH (6.5%-21% O 2 , 90 s/cycle, 12 h/day) or room air (RA, 21% O 2 , 24 h/day) for short-term (6 weeks) or long-term (6 months) (n = 10/group). Short-term mice were examined for arterial stiffness by pulse wave velocity (PWV) and atomic force microscopy, while long-term mice were used for AAA studies. To induce AAA, mice were infused with Ang II (1 μg/kg/min) using osmotic minipumps during final 14 days of IH or RA exposure. Sham surgery was performed in control mice. Outcomes were assessed via transabdominal ultrasound imaging and histology. Results: Short-term IH exposure decreased the stiffness of the abdominal (0.88 vs. 2.32 m/s in RA; p=0.0006 ) and thoracic (2.0 vs. 3.5 kPa in RA; p=0.01 ) aorta. Ang II increased abdominal aortic diameter in RA mice compared to sham and long-term IH with Ang II further augmented the aortic diameter (1.56 vs. 1.34 mm in RA Ang II; p=0.03 ) and incidence of AAA (50 vs. 10% in RA Ang II; p=0.05 ). Histologically, long-term IH plus Ang II augmented medial elastin fragmentation (7.7 vs. 5.3 in RA Ang II; p=0.04 ) and aortic collagen content (3.1 vs. 1.3 in RA Ang II; p=0.06 ). Ang II tended to non-significantly increase PWV in both groups (RA sham 1.9 vs. RA Ang II 2.5 and IH Ang II 2.3 m/s). Notably, a negative correlation between maximum aortic diameter and PWV was observed in AAA-induced mice (R 2 =0.48, p=0.0009 ). Conclusions: IH favors AAA development in association with changes in aortic stiffness. These findings support a potential causal link between OSA and AAA pathogenesis. Clarification of the molecular mechanisms may reveal novel therapeutic targets for the management of AAA.

Racial Disparity in Microvascular Function in Men with Newly Diagnosed Prostate Cancer

BACKGROUND:Cardiovascular disease (CVD) is a leading cause of death in men with prostate cancer. In addition, non-Hispanic Black (NHB) men experience worse CVD-related mortality compared to their non-Hispanic White (NHW) counterparts, although the reason for this racial disparity remains unclear. Notably, vascular endothelial dysfunction often precedes the emergence of overt CVD. Indeed, conduit-vessel dysfunction, micro-vascular dysfunction, and arterial stiffness are independent predictors of CVD risk. Thus, the purpose of this study was to comprehensively assess vascular health in recently diagnosed NHB and NHW men with prostate cancer. Methods: Twenty-eight men (10 NHW, 18 NHB) with a new clinical diagnosis of prostate cancer (within 3 months) participated in this study. Flow-mediated dilation (FMD) was performed to represent conduit-vessel vascular endothelial function. Cutaneous post occlusive reactive hyperemia (PORH) with local thermal heating (LTH) and iontophoresis of acetylcholine were performed to represent various mechanisms regulating microvascular function. Lastly, pulse wave velocity (PWV) and pulse wave analysis (PWA) were performed to assess central and aortic stiffness, respectively. Data are reported as mean ± SD. Results: A 4-year age difference ( p=0.131) was observed between NHB (65±7 years) and NHW (69±6 years) men. No differences in BMI or clinical laboratory values were observed between NHB and NHW patients (all p&gt;0.05). NHB men exhibited significantly lower microvascular function compared to NHW men, including PORH (NHB: 117±44 PU vs NHW: 207±47 PU; p&lt;0.001), LTH (NHB: 180±73 PU vs NHW: 281±65 PU; p=0.003), and iontophoresis (NHB: 67±28 PU vs NHW: 136±38 PU; p&lt;0.001). No differences in FMD ( p=0.596), PWV ( p=0.695), or PWA ( p=0.883) were observed between groups. CONCLUSION: The results of the current study provide compelling evidence that microvascular dysfunction is present in NHB men who are recently diagnosed with prostate cancer compared to their NHW counterparts. Given that NHB men were 4 years younger, these data support that the microvascular dysfunction may accelerate vascular aging and contribute to the racial disparity in CVD following prostate cancer diagnosis. Supported by: AHA SFRN 863621 (RAH). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluating the Role of LOXL2 in Post-menopausal Arterial Stiffening

Introduction: Cardiovascular disease (CVD) is the number one cause of death for both men and women. Even though pre-menopausal women are relatively protected from CVD, a disproportionate increase in CVD risk and incidence occurs after menopause. Aortic stiffening, as occurs in aging, is predictive of major adverse cardiovascular events, independent from the traditional CVD risk factors. Epidemiological studies have shown that older, post-menopausal women exhibit an accelerated pace of aortic stiffening, eventually surpassing age-matched men, with exacerbated isolated systolic hypertension, diastolic dysfunction, and left ventricular remodeling. The hormonal shift, particularly loss of estrogen, present in post-menopausal women has also been widely studied; however, it is increasingly clear that estrogen loss alone is not responsible for the elevated CVD risk. More recently, a shift to androgen signaling has emerged as a key facet in post-menopausal women's health. Thus, mechanistic differences and manifestations of arterial stiffness in men and women require further investigation to help identify and develop novel risk assessment tools and therapeutic targets. Here we propose LOXL2, a key matrix remodeling enzyme, as a potential therapeutic target. In this study, we determined if post-menopausal females present accelerated arterial stiffening, and an abrupt and larger increase in LOXL2. We also studied the effect of sex hormones in LOXL2 activation. Methods and results: Male and female C57Bl/6J mice were used. Female mice underwent ovariectomy (OVX) or sham surgery at 10 weeks old. Three groups were compared: 1) OVX, 2) sham control females, and 3) age-matched males. Body weight, pulse wave velocity (PWV, the gold-standard index of in vivo arterial stiffening), and blood pressure (BP) were measured non-invasively from 12 to 53 weeks old. Results showed a significant increase in both body weight and PWV in the OVX females compared to sham females and males. BP remained similar for all groups, with a slight increase in OVX females. Mice were dissected, and aorta and heart were extracted and prepared for Western blotting measurements. OVX mice showed a low heart to body weight ratio. Western blotting (pilot data) revealed an increasing trend in LOXL2, ERα, and ERβ in the aorta and heart of OVX females. To test LOXL2 activation by sex hormones in vitro, human aortic smooth muscle cells (HASMC) and human aortic endothelial cells (HAEC) were exposed to dihydrotestosterone (DHT) and estradiol (E2) concentrations that mimic the hormonal levels of menstruating women, post-menopausal women, and men (post-puberty) for 16h. Western blotting showed highest levels of LOXL2 when mimicking the post-menopausal women hormonal levels in HASMCs but not in HAECs. Conclusion: Vascular stiffness is exacerbated in OVX females compared to sham females and males. OVX mice present a higher LOXL2 protein abundance in the aorta and heart, as well as increased ERα and ERβ. LOXL2 is modulated by sex hormones, showing significant increase when mimicking post-menopausal women’ hormonal levels. Future studies will continue to: 1) determine the molecular mechanisms underlaying increased arterial stiffness in females after menopause, 2) identify and test novel targets to stop and/or reverse this increase in vascular stiffening, and 3) study the role of hormonal shift in old females in arterial aging. NHLBI grant R01HL148112 01 (L.S.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Presence of XX Sex Chromosome Complement Increases Aortic Circumferential Stiffness in Female Mice

Elastin and collagen uniquely adapt to the mechanical demands of high pulsatile pressure in the vascular system in conjunction with the extracellular matrix (ECM). Elastic fiber networks and collagen are affected by component disorganization, leading to an array of vascular diseases and compromised mechanical behavior. It is shown that women than men have accelerated arterial stiffening. Previously, we have shown increased axial and circumferential linearized material stiffness in the carotid arteries of female than male wildtype mice. Whether sex hormones interact with sex chromosomes is unknown. Therefore, we hypothesize that sex hormones interact with sex chromosomes to increase aortic circumferential stiffening in female than male mice. In this study, we used gonadal intact 15-week-old four core genotype mice (n=4-6/group) comprising female (F) and male (M) mice with either XX or XY sex chromosome complement (SCC). Using a tissue puller, we assessed the stress-strain and displacement-force relationship of the abdominal aorta. Briefly, the aorta was cut into 3mm rings and pulled apart to a range of 1300 μm with a velocity of 35 μm/sec. To determine the load-bearing effect of collagen and elastin, collagenase type II (16 units) and elastase (5 units) were used to digest the aortic ring before pulling. Part of the aortic ring was digested for a PCR array of extracellular matrix and adhesion molecules. We observed a leftward shift of stress-strain in XXF than in XXM (P=0.03). A leftward shift of stress-strain was also indicated in XXF than in XYM mice (P=0.004). Displacement-force tests showed a similar effect with a leftward shift in XXF than XXM (P=0.01). A leftward shift of displacement force was also indicated in XXF than in XYM (P=0.004). Aorta digestion with elastase reversed the phenotype, showing a leftward shift of displacement force in XXM than in XXF (P=0.02). Collagenase digestion removed the observed sex differences in stress-strain and displacement force tests. The PCR array comparing XXF and XXM showed increased fold change in Adamts5 (4.2), Emilin (2.2), Icam1 (2.4), and Thbs2 (3). We also observed the downregulation of Cntn1 (0.4), Cntnna1 (0.5), Ecm1 (0.3), and Fbln1 (4). Our data suggested that XX sex chromosome complement, and ECM genes contribute to the structural stiffness of female mice aorta. Our study will contribute to understanding connective tissue diseases, including arterial stiffness, aortic aneurysms, Marfan and Danlos syndrome. HL105400 and HL155841. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of At-Risk Drinking on Ambulatory Blood Pressure in Young Adults

Introduction: At-risk drinking is associated with an increased risk of cardiovascular diseases (CVD) even in young adults. However, this association is mainly based on offce blood pressure (BP) measurement. Ambulatory BP monitoring captures diurnal variation in BP and is a more sensitive CVD predictor than offce BP. Therefore, the purpose of this study is to investigate the effects of at-risk drinking on ambulatory BP in young healthy adults with normal offce BP. Method: A total of 20 healthy men and women (21-35 years), non-smokers, were included in this cross-sectional study. All participants had an offce BP lower than 130/80 mmHg. Using the US Alcohol Use Disorders Identification Test (USAUDIT), at-risk drinkers were defined as those having a total USAUDIT score higher than 7 for men (6 for women). All participants underwent 24-hour ambulatory BP monitoring (Oscar 2™, SunTech Medical®). To investigate the vascular mechanisms underlying the effects of at-risk drinking on ambulatory blood pressure, aortic arterial stiffness and wave reflection were measured as pulse wave velocity (PWV) and augmentation index (AIx) by using SphygmoCor XCEL system (AtCor Medical). Results: No differences were found in age and BMI between at-risk drinkers (n=10) vs. low-risk drinkers (n=10; mean ± SD for age: 26.7 ± 3.7 vs. 26.6 ± 4.3 years, P&gt;0.99 and BMI: 24.5 ± 2.4 vs. 23.8 ± 2.9 kg/m2, P=0.6). At-risk drinkers had a higher total USAUDIT score (10.6 ± 2.7 vs. 1.4 ± 1.2, p&lt;0.001). While there was no difference between at-risk drinkers and low-risk drinkers in 24-hour, daytime, and nighttime systolic and diastolic BP (P≥0.5), at-risk drinkers had a higher blood pressure morning surge compared to low-risk drinkers (systolic: 34 ± 10 vs. 22 ± 6 mmHg, P=0.014 and diastolic: 29 ± 9 vs. 15 ± 4 mmHg, P=0.002). No significant difference was found in PWV (5.7 ± 0.6 Vs. 5.5 ± 0.7 m/sec, P=0.4) and AIx (8 ± 8 Vs. 15 ± 11, P=0.1). Conclusion: Our results indicate that despite similar offce BP, young adult at-risk drinkers had higher BP morning surge, an independent risk factor for cardiovascular events, than low-risk drinkers. These findings provide implications in using USAUDIT and out-of-offce BP measurements for cardiovascular disease risk assessment. This work was supported by NIAAA AA028537 to CLH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cerebrovascular Dysfunction in a Mouse Model of Marfan Syndrome: Increased Vulnerability to Neuropathology &amp; Mild Traumatic Brain Injury

Marfan syndrome (MFS) is a connective tissue disorder (CTD) associated with mutations in fibrillin-1 ( Fbn1), leading to chronic systemic increases in transforming growth factor-β (TGF-β) availability and signaling that could lead to aortic wall weakening and aneurysm/rupture. TGF-β has been implicated in cerebrovascular dysfunction, loss of blood-brain barrier (BBB) integrity, age-related neuroinflammation and neurological deficits. Improvements in MFS treatment and life expectancy have uncovered a risk for systemic vascular dysfunction including cerebrovascular complications such as stroke, and cerebral aneurysm. Therefore, we hypothesized that Fbn1 mutation ( Fbn1C1041G/+) is associated with systemic vascular dysfunction, BBB permeability, neuroinflammation, neurobehavioral alterations, and impaired glutamate homeostasis, leaving the brain more vulnerable to mild traumatic brain injury (mTBI). Our experimental groups included: 6M-old male and female MFS ( Fbn1C1041G/+) and C57BL/6 (WT) control, and middle-aged 12M WT mice (N=3-10/group, P &lt; 0.05). In vivo ultrasound imaging analyzed by two blinded investigators demonstrated increased aortic root diameters and stiffness in MFS mice compared to 6M and 12M WT mice, where MFS male diameters were affected more than females. Vascular dysfunction measured by blood flow velocity (BFV) extended to the left pulmonary artery where 6M MFS and 12M WT mice were reduced compared to 6M WT mice. This reduction continued through decreased posterior cerebral artery BFV in MFS males, where MFS females were comparable to 6 and 12M WT females. In 6M MFS male mice, Evans blue extravasation and Immunoglobulin G staining demonstrated increased BBB permeability in the hippocampus to large and small molecules, respectively, as well as to small molecules in the lateral hypothalamus as compared to 6M WT and like 12M WT. In adjacent sections, iba-1-stained cells had morphologies indicative of reactive microglia. In vivo electrochemical recordings in the hippocampus showed a trend towards lowered peak glutamate amplitudes and elevated baseline glutamate concentrations in MFS and 12M WT mice demonstrating disrupted glutamate homeostasis. Furthermore, exogenous TGF-β applied in the lateral hippocampus of 6M WT males revealed an evoked glutamate response that may support this elevated baseline in MFS mice. Higher neurobehavioral severity scale (NSS) scores in 6M MFS mice suggested neurobehavioral alterations that were more like 12M WT. Midline fluid percussion was used to induce mTBI, where 6M MFS male mice and both female groups required a 15% lower pressure to induce mTBI righting reflex times (5-10 minutes) compared to 6M WT male mice. Mice were evaluated at 1-day post injury, where BBB permeability to large and small molecules and microglia activation were increased, glutamate clearance was slowed, and NSS scores were increased compared to 6M WT and were like 6M MFS and 12M WT mice. These novel findings signify MFS as a condition of systemic vascular dysfunction and pre-mature cerebrovascular aging phenotype with more vulnerability to brain injury. Funding: NIH-R36AG083385, Valley Research Partnership-P1A-5012, NIH-R15HL145646, NIH-R01NS100793, Midwestern Graduate Funds, Phoenix Children’s Hospital Leadership Circle, Graduate and Professional Council Research and Projects Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The influence of perceived discrimination on aortic hemodynamics in young Black adults

Black adults experience the greatest prevalence of cardiovascular disease (CVD) risk factors and higher CVD mortality of any racial or ethnic group in the United States. The chronic stress from experiencing racial discrimination may exert a weathering effect that contributes to cardiovascular health inequities observed among Black adults. Prior evidence has suggested that Black adults experience greater aortic stiffness as compared with white adults. However, there is limited information regarding perceived racial discrimination and aortic hemodynamics in young adults. Purpose/Hypothesis: The purpose of this study was to determine whether perceived racial discrimination was associated with worse aortic hemodynamics in young Black adults. Methods: Black adults aged 18-25 (n=18, 44% female) volunteered to participate in this study. Participants arrived at the lab at 7:00AM in a fasted state. Following 30 minutes of rest, central pressure waveforms were derived from the radial artery waveform acquired via applanation tonometry and the use of the generalized transfer function. We report aortic augmentation pressure (AP, mmHg), augmentation index (AIx, %), augmentation index normalized to a heart rate of 75bpm (AIx75), round trip transit time (Tr, ms), and the subendocardial viability ratio (SEVR, %), also known as the Buckberg Index. Peak oxygen consumption (VO2 peak) was measured via Indirect calorimetry during a graded treadmill test. Participants completed a questionnaire that assessed personal-level and group-level discrimination. Partial correlations (Pearson’s r controlled for VO2 peak) were used to assess the association between perceived racial discrimination and aortic hemodynamics. Results: Perceived group-level discrimination was positively associated with AP (r = 0.571, p = 0.026), AIx (r = 0.580, p = 0.023), and AIx75 (r = 0.571, p = 0.026), signifying worse central hemodynamics that are indicative of increased left ventricular systolic load. However, perceived personal-level discrimination was not associated with aortic hemodynamics (ps&gt;0.05). VO2peak was positively associated with Tr (r = 0.511, p = 0.043), signifying a later return of the reflected wave (i.e, better) to the heart to facilitate coronary perfusion during diastole. VO2 peak was also inversely associated with AIx75 (r = -0.657, p = 0.006). Conclusion: These preliminary data indicate that young Black adults who report higher group-level discrimination have an increased left ventricular systolic afterload in the aorta. Future studies investigating coping strategies or the effects of increased fitness to improve central hemodynamics in Black adults are warranted. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

VISCERAL FAT TISSUE AS A SIGNIFICANT CARDIOVASCULAR RISK FACTOR IN CORRELATION WITH SUBCLINICAL ORGAN DAMAGE IN POSTMENOPAUSAL WOMEN

Objective: Postmenopausal women are a special group of the cardiological patients. Every effort should be made to search for subclinical organ damage in this group, the presence of which correlates with the amount of visceral fat tissue. Design and method: We examined 156 postmenopausal women. The average age of them was 65,3 years old. 41% of them had type 2 diabetes; 46% of them were taking statins. Pulse wave velocity (PWV), systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI) and lipid profile were evaluated. Visceral fat tissue, body weight and fat mass were performed by Tanita MC980 MA Plus analyzer. We assessed cardiovascular risk according to: SCORE2 and SCORE2- OP scales. Statistical calculations were performed in the StatSoft Statistica 10: ?Spearmana was taken to analyze the correlation of statistically significant values. Results: We revealed following results [∗for p&lt;= 0,05; ∗∗for p&lt;0,001]. People with higher body weight characterized by higher SBP and DBP. Lower fat mass and BMI resulted with lower DBP. The lower fat mass, BMI and the amount of visceral fat tissue, the higher HDL cholesterol level. People with higher fat mass, BMI and the amount of visceral fat tissue were more likely to have type 2 diabetes.Patients with higher amount of visceral fat tissue characterized by greater aortic stiffness and more often required lipid-lowering therapy. The amount of visceral fat tissue correlated with age of the patients and their cardiovascular risk assessed by SCORE2/SCORE2OP scales. Conclusions: The amount of visceral fat tissue should be taken into account in assessing the patient‘s cardiovascular risk and occurrence of cardiological subclinical organ damage. Weight loss must be considered as an important factor in the reducing of blood pressure. The likelihood of developing type 2 diabetes is correlated with higher BMI and fat mass. Reduction of BMI, fat mass and the amount of visceral fat tissue results with better lipid profile. Greater amount of visceral fat tissue results in more frequent need of starting lipid-lowering therapy.

Deletion of Sigmar1 leads to increased arterial stiffness and altered mitochondrial respiration resulting in vascular dysfunction.

Sigmar1 is a ubiquitously expressed, multifunctional protein known for its cardioprotective roles in cardiovascular diseases. While accumulating evidence indicate a critical role of Sigmar1 in cardiac biology, its physiological function in the vasculature remains unknown. In this study, we characterized the expression of Sigmar1 in the vascular wall and assessed its physiological function in the vascular system using global Sigmar1 knockout (Sigmar1-/-) mice. We determined the expression of Sigmar1 in the vascular tissue using immunostaining and biochemical experiments in both human and mouse blood vessels. Deletion of Sigmar1 globally in mice (Sigmar1-/-) led to blood vessel wall reorganizations characterized by nuclei disarray of vascular smooth muscle cells, altered organizations of elastic lamina, and higher collagen fibers deposition in and around the arteries compared to wildtype littermate controls (Wt). Vascular function was assessed in mice using non-invasive time-transit method of aortic stiffness measurement and flow-mediated dilation (FMD) of the left femoral artery. Sigmar1-/- mice showed a notable increase in arterial stiffness in the abdominal aorta and failed to increase the vessel diameter in response to reactive-hyperemia compared to Wt. This was consistent with reduced plasma and tissue nitric-oxide bioavailability (NOx) and decreased phosphorylation of endothelial nitric oxide synthase (eNOS) in the aorta of Sigmar1-/- mice. Ultrastructural analysis by transmission electron microscopy (TEM) of aorta sections showed accumulation of elongated shaped mitochondria in both vascular smooth muscle and endothelial cells of Sigmar1-/- mice. In accordance, decreased mitochondrial respirometry parameters were found in ex-vivo aortic rings from Sigmar1 deficient mice compared to Wt controls. These data indicate a potential role of Sigmar1 in maintaining vascular homeostasis.

Case Report: Marfan’s Syndrome with Neurofibromatosis Type-2

Background Marfan’s syndrome (MFS) and neurofibromatosis type-2 (NF-2) are rare autosomal dominant diseases caused due to mutations in chromosome number 15 and 22, respectively. The chance of both the diseases occurring in the same patient is extremely rare. Case presentation In this report a rare case of a 16-year-old boy having a coexistence of both MFS and NF-2 is reported. The clinical findings consisted of musculoskeletal abnormalities consisting of laxity of joints, positive Steinberg thumb sign test, positive Walker-Murdoch wrist test, dolichostenomelia, and arachnodactyly. Anthropometric abnormalities reported an increase in lower segment height than the upper segment. Diagnostic assessment revealed pectus carinatum, multiple meningioma, and heterogeneous lesions in bilateral cerebellopontine angle that were ruled out as bilateral schwannoma confirming the diagnosis of MFS and NF-2. However, both must be regarded as novel mutations, and as the position of the two genes is unrelated, it is most probable that two different mutations have occurred. β-blocker was recommended as a prophylactic measure to minimize aortic root stiffness and control aortic root dilatation. Furthermore, surgery and radiation therapy were planned for the management of NF-2; however, the patient expressed skepticism regarding the course of treatment and follow-ups; as a result, this data was reported at the time of discharge with non-specified duration of follow-ups. Conclusions This case report demonstrates a rare case of MFS which is caused due to mutation in chromosome number 15 along with NF-2 which is caused due to mutation in chromosome number 22. Since the positions of the two genes are unrelated, it is concluded that two distinct mutations have occurred. As a result, this report highlights a rare coexistence of both mutations, which will benefit the medical profession in enhancing future studies.

Serum Lipoprotein(a) Levels as a Predictor of Aortic Stiffness in Patients on Long-Term Peritoneal Dialysis.

BACKGROUND Lipoprotein (a) [Lp(a)] is associated with atherosclerosis and cardiovascular mortality in patients with kidney failure. Aortic stiffness (AS), measured primarily by carotid-femoral pulse wave velocity (cfPWV), reflects vascular aging and precedes end-organ failure. This study aimed to evaluate the association between serum Lp(a) levels and cfPWV in patients undergoing peritoneal dialysis (PD). MATERIAL AND METHODS In this cross-sectional study, which included 148 patients with long-term PD for end-stage kidney failure, cfPWV was measured using a cuff-based method. AS was defined as a cfPWV exceeding 10 m/s, and an enzyme-linked immunosorbent assay was used to determine serum Lp(a) levels. Univariate and multivariate regression analyses were performed to identify the clinical correlates of AS. RESULTS There were 32 (21.6%) patients diagnosed with AS. Based on the multivariate logistic regression analysis, the odds ratio for AS was 1.007 (95% confidence interval, 1.003-1.011; P=0.001) for every 1 mg/L increase in Lp(a) levels. Multivariate linear regression analysis showed that Lp(a) (P<0.001), age (P=0.003), waist circumference (P=0.008), systolic blood pressure (P=0.010), and diabetes mellitus (P<0.001) were positively associated with cfPWV. The area under the receiver operating characteristic curve for Lp(a) in differentiating AS from non-AS was 0.770 (95% confidence interval, 0.694-0.835; P<0.0001). CONCLUSIONS Serum Lp(a) level was independently associated with cfPWV and AS in patients with PD.

Non-Invasive Assessment of Micro- and Macrovascular Function after Initiation of JAK Inhibitors in Patients with Rheumatoid Arthritis.

Janus kinase (JAK) inhibitors constitute a novel class of oral biologic disease-modifying antirheumatic drugs for patients with rheumatoid arthritis (RA). However, their use has been associated with increased risk of major cardiovascular events. We investigated whether treatment with JAK inhibitors exerts significant alterations in the micro- and microvasculature in RA patients. Thirteen patients with RA initiating treatment with JAK inhibitors were prospectively studied. Eventually, data from 11 patients who completed the study were analyzed. Procedures were performed at baseline and 3 months after treatment. Nailfold videocapillaroscopy was applied to detect alterations of the dermal capillary network. Participants underwent 24 h ambulatory blood pressure monitoring (Mobil-O-Graph device) for the assessment of blood pressure (both brachial and aortic) and markers of large artery stiffening [pulse wave velocity (PWV), augmentation index] throughout the whole 24 h and the respective day- and nighttime periods. Carotid intima-media thickness was assessed with ultrasound. Three-month treatment with JAK inhibitors was not associated with any differences in brachial and aortic blood pressure, arterial stiffness, and carotid atherosclerosis, with the only exception of nighttime PWV, which was significantly elevated at follow-up. However, three-month treatment with JAK inhibitors induced significant microvascular alterations and increased the total number of capillaroscopic abnormalities. Three-month treatment with JAK inhibitors may exert significant effects on microcirculation as assessed with nailfold videocapillaroscopy, whereas macrovascular structure and function appears largely unaffected. Further research toward this direction may add substantial information to the available literature regarding cardiovascular aspects of JAK inhibitors in RA.