The importance of endothelial dysfunction in resistance artery remodelling and cardiovascular risk

Reduced intestinal butyrate availability is associated with the vascular remodeling in resistance arteries of hypertensive rats

During hypertension an unbalance of short-chain fatty acids (SCFAs) production by intestinal bacteria is described. However, no data evaluate the association of SCFAs and vascular remodeling in hypertension, which is an important hallmark of this disease. Thus, the present study aims to evaluate the correlations between SCFAs availability and the resistance arteries remodeling in hypertension, as well as to identify the possible pathway by which the SCFAs could exert a structural and mechanical influence. Hence, male spontaneously hypertensive rats (SHR) and normotensive Wistar rats had blood pressure measured by tail-cuff plethysmography; fecal SCFAs content assessed by gas chromatography; gene expression of SCFAs-transporters in gut epithelium and SCFAs-sensing receptors on mesenteric resistance arteries (MRA) quantified by PCR; and MRA structural and mechanical parameters analyzed by pressure myograph. Reduced butyrate fecal content was found in SHR, with no changes in propionate and acetate, as well as decreased mRNA levels of SCFAs-transporters (MCT1, MCT4, and SMCT1) in the intestinal epithelium. In addition, lower gene expression of SCFAs-sensing receptors (GPR41, GPR43, and GPR109a, but not Olfr78) was identified in MRAs of SHR, which also shows inward eutrophic remodeling with stiffness. Butyrate content presented a negative correlation with systolic blood pressure and with the structural alterations found on MRAs, while a positive correlation between butyrate content and mechanical parameters was detected. Altogether the present study suggests that lower butyrate content due to ineffective SCFA bioavailability, associated with lower SCFAs-sensing receptors expression, could favor MRA remodeling, increasing peripheral vascular resistance and worsening hypertension prognosis.

Oxidative Stress in Arterial Hypertension (HTN): The Nuclear Factor Erythroid Factor 2-Related Factor 2 (Nrf2) Pathway, Implications and Future Perspectives

Arterial hypertension (HTN) is one of the most prevalent entities globally, characterized by increased incidence and heterogeneous pathophysiology. Among possible etiologies, oxidative stress (OS) is currently extensively studied, with emerging evidence showing its involvement in endothelial dysfunction and in different cardiovascular diseases (CVD) such as HTN, as well as its potential as a therapeutic target. While there is a clear physiological equilibrium between reactive oxygen species (ROS) and antioxidants essential for many cellular functions, excessive levels of ROS lead to vascular cell impairment with decreased nitric oxide (NO) availability and vasoconstriction, which promotes HTN. On the other hand, transcription factors such as nuclear factor erythroid factor 2-related factor 2 (Nrf2) mediate antioxidant response pathways and maintain cellular reduction-oxidation homeostasis, exerting protective effects. In this review, we describe the relationship between OS and hypertension-induced endothelial dysfunction and the involvement and therapeutic potential of Nrf2 in HTN.

Vena cava presents endothelial dysfunction prior to thoracic aorta in heart failure: the pivotal role of nNOS uncoupling/oxidative stress

Arterial endothelial dysfunction has been extensively studied in heart failure (HF). However, little is known about the adjustments shown by the venous system in this condition. Considering that inferior vena cava (VC) tone could influence cardiac performance and HF prognosis, the aim of the present study was to assess the VC and thoracic aorta (TA) endothelial function of HF-post-myocardial infarction (MI) rats, comparing both endothelial responses and signaling pathways developed. Vascular reactivity of TA and VC from HF post-MI and sham operated (SO) rats was assessed with a wire myograph, 4 weeks after coronary artery occlusion surgery. Nitric oxide (NO), H2O2 production and oxidative stress were evaluated in situ with fluorescent probes, while protein expression and dimer/monomer ratio was assessed by Western blot. VC from HF rats presented endothelial dysfunction, while TA exhibited higher acetylcholine (ACh)-induced vasodilation when compared with vessels from SO rats. TA exhibited increased ACh-induced NO production due to a higher coupling of endothelial and neuronal NO synthases isoforms (eNOS, nNOS), and enhanced expression of antioxidant enzymes. These adjustments, however, were absent in VC of HF post-MI rats, which exhibited uncoupled nNOS, oxidative stress and higher H2O2 bioavailability. Altogether, the present study suggests a differential regulation of endothelial function between VC and TA of HF post-MI rats, most likely due to nNOS uncoupling and compromised antioxidant defense.

Donepezil improves vascular function in a mouse model of Alzheimer's disease

Cardiovascular complications in Alzheimer's disease (AD) patients can occur years to decades prior to the onset of clinical symptoms of the disease. Donepezil represents the most effective drug in the treatment of AD. However, the potential effect of donepezil on vascular function and structure remains largely unexplored. Here, we assessed the impact of donepezil on the vascular phenotype of an established model of accelerated senescence that develops spontaneously AD, the SAMP8 mouse. Three groups of animals were included: SAMR1 (control strain), SAMP8, and SAMP8 treated with donepezil. Treatment with donepezil was administered from the 4th to the 6th month of life. At 6 months, after cognitive tests by Morris Water Maze, animals were euthanized, and their mesenteric arteries were processed for functional experiments. Untreated SAMP8 developed cognitive impairment compared to SAMR1, while donepezil treatment significantly attenuated cognitive dysfunction. SAMP8 exhibited a higher media-to-lumen ratio than SAMR1 and donepezil-treated animals. Endothelial function was impaired in SAMP8 animals compared to SAMR1. The addition of vitamin C improved the vasodilatory response to acetylcholine in SAMP8. Treatment with donepezil improved endothelial function in SAMP8 animals and reduced the additional vasodilation induced by vitamin C. In conclusion, in the SAMP8 AD model, cognitive impairment is associated with endothelial dysfunction and vascular remodeling which could contribute to cardiovascular events in AD since the prodromal phases of the disease. Treatment with donepezil alleviates vascular dysfunction associated with AD through an increase in NO availability likely by counteracting inflammation and oxidative stress.

Clinical Relevance of the Sympathetic-Vascular Interactions in Health and Disease

The sympathetic nervous system is known to play a pivotal role in the short- and long-term regulation of different cardiovascular functions. In recent decades, increasing evidence has demonstrated that sympathetic neural influences are involved not only in the vasomotor modulation of small resistance arteries but also in the control of large arteries. Sympathetic activity and vascular function, which are key factors in the pathophysiology and prognosis of cardiovascular disease, are linked by a close relationship. Evidence from experimental studies indicates that the sympathetic nervous system is critically influenced, at the central and also at the peripheral level, by the most relevant factors regulating vascular function, namely nitric oxide, reactive oxygen species and endothelin. Additionally, there is evidence of a reciprocal influence between endothelial function and sympathetic mechanisms. This paper will provide an overview of the relationships between endothelial function and the sympathetic nervous system characterizing physiological states. It will also briefly mention the alterations described in cardiovascular disease, with particular emphasis on essential hypertension and congestive heart failure, i.e., the two pathological states in which endothelial dysfunction and neuroadrenergic activation appear to be relevant factors for determining cardiovascular prognosis.

Assessment and pathophysiology of microvascular disease: recent progress and clinical implications

The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction.

The Complex Relationship Between Serum Uric Acid, Endothelial Function and Small Vessel Remodeling in Humans

Aims: The relationship between serum uric acid (SUA) and microvascular remodeling in humans remains largely unexplored. We assessed whether SUA provides additional information on the severity of microvascular remodeling than that obtained from the European Heart Score (HS), the patterns of microvascular remodeling associated with changes in SUA levels and the mediation by endothelial function and nitric oxide (NO) availability on this relationship. Methods: A total of 162 patients included in the microvascular dataset of the Italian Society of Hypertension with available information on SUA, media-to-lumen (M/L) ratio, media cross-sectional area (MCSA), endothelial function, NO availability and HS were included in the analysis. The top tertile of M/L ratio and MCSA were used to define severe microvascular remodeling. Results: A U-shaped association was observed between SUA and both M/L ratio and MCSA. Adjustment for HS did not affect these associations. SUA was able to reclassify a significant number of subjects without, and with, severe M/L ratio and MCSA remodeling over the HS alone. The microvascular remodeling associated with SUA levels presented a predominant hypertrophic pattern. SUA was inversely associated with endothelial function and NO availability. Structural equation modeling analysis controlling for the HS suggested that the association of SUA with M/L ratio and MCSA was mediated through changes in endothelial function and NO availability. Conclusions: The addition of SUA to the HS improves the identification of subjects with greater microvascular remodeling. The relationship between SUA and microvascular remodeling is mediated by endothelial function and NO availability.

Ubiquinol Ameliorates Endothelial Dysfunction in Subjects with Mild-to-Moderate Dyslipidemia: A Randomized Clinical Trial

In this randomized, double-blind, single-center trial (ANZCTR number ACTRN12619000436178) we aimed to investigate changes in endothelium-dependent vasodilation induced by ubiquinol, the reduced form of coenzyme Q10 (CoQ10), in healthy subjects with moderate dyslipidemia. Fifty-one subjects with low-density lipoprotein (LDL) cholesterol levels of 130–200 mg/dL, not taking statins or other lipid lowering treatments, moderate (2.5%–6.0%) endothelial dysfunction as measured by flow-mediated dilation (FMD) of the brachial artery, and no clinical signs of cardiovascular disease were randomized to receive either ubiquinol (200 or 100 mg/day) or placebo for 8 weeks. The primary outcome measure was the effect of ubiquinol supplementation on FMD at the end of the study. Secondary outcomes included changes in FMD on week 4, changes in total and oxidized plasma CoQ10 on week 4 and week 8, and changes in serum nitrate and nitrite levels (NOx), and plasma LDL susceptibility to oxidation in vitro on week 8. Analysis of the data of the 48 participants who completed the study demonstrated a significantly increased FMD in both treated groups compared with the placebo group (200 mg/day, +1.28% ± 0.90%; 100 mg/day, +1.34% ± 1.44%; p < 0.001) and a marked increase in plasma CoQ10, either total (p < 0.001) and reduced (p < 0.001). Serum NOx increased significantly and dose-dependently in all treated subjects (p = 0.016), while LDL oxidation lag time improved significantly in those receiving 200 mg/day (p = 0.017). Ubiquinol significantly ameliorated dyslipidemia-related endothelial dysfunction. This effect was strongly related to increased nitric oxide bioavailability and was partly mediated by enhanced LDL antioxidant protection.