Immune System and Microvascular Remodeling in Humans

Novel biomarkers in patients with uncontrolled hypertension with and without kidney damage

INTRODUCTION

Estimated glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (ACR) are insensitive biomarkers for early detection of hypertension-mediated organ damage (HMOD). In this nationwide cross-sectional study, we assessed potential biomarkers for early HMOD in healthy persons and patients with hypertension. We hypothesised that plasma levels of biomarkers: (1) are different between healthy controls and patients with hypertension, (2): can classify patients with hypertension according to the degree of hypertension severity.

DESIGN AND METHODS

Patients with hypertension prescribed ≥2 antihypertensive agents were selected from a multicentre study. Healthy controls were selected from an ongoing study of living kidney donor candidates. Uncontrolled hypertension was defined as systolic daytime ambulatory blood pressure ≥135 mmHg. Kidney HMOD was defined by ACR > 3.0 mg/mmol or eGFR < 60 mL/min/1.73 m2. Patients with hypertension were categorised into three groups: (1) controlled hypertension; (2) uncontrolled hypertension without kidney HMOD; (3) uncontrolled hypertension with kidney HMOD. Fifteen biomarkers were analysed using a Luminex bead-based immunoassay, and nine fell within the specified analytical range.

RESULTS

Plasma levels of Interleukin 1 receptor antagonist (IL-1RA), neutrophil gelatinase-associated lipocalin (NGAL) and uromodulin were significantly different between healthy controls (n = 39) and patients with hypertension (n = 176). In regression models, with controlled hypertension (n = 55) as the reference category, none of the biomarkers were associated with uncontrolled hypertension without (n = 59) and with (n = 62) kidney HMOD. In models adjusted for cardiovascular risk factors and eGFR, osteopontin (OPN) was associated with uncontrolled hypertension without kidney HMOD (odds ratio (OR) 1.77 (1.05-2.98), p = 0.03), and regulated upon activation normal T-cell expressed and secreted (RANTES) with uncontrolled hypertension with kidney HMOD (OR 0.57 (0.34-0.95), p = 0.03).

CONCLUSIONS

None of the biomarkers could differentiate our hypertension groups when established risk factors were considered. Plasma OPN may identify patients with uncontrolled hypertension at risk for kidney HMOD.

Immune and inflammatory mechanisms in hypertension

Hypertension is a global health problem, with >1.3 billion individuals with high blood pressure worldwide. In this Review, we present an inflammatory paradigm for hypertension, emphasizing the crucial roles of immune cells, cytokines and chemokines in disease initiation and progression. T cells, monocytes, macrophages, dendritic cells, B cells and natural killer cells are all implicated in hypertension. Neoantigens, the NLRP3 inflammasome and increased sympathetic outflow, as well as cytokines (including IL-6, IL-7, IL-15, IL-18 and IL-21) and a high-salt environment, can contribute to immune activation in hypertension. The activated immune cells migrate to target organs such as arteries (especially the perivascular fat and adventitia), kidneys, the heart and the brain, where they release effector cytokines that elevate blood pressure and cause vascular remodelling, renal damage, cardiac hypertrophy, cognitive impairment and dementia. IL-17 secreted by CD4+ T helper 17 cells and γδ T cells, and interferon-γ and tumour necrosis factor secreted by immunosenescent CD8+ T cells, exert crucial effector roles in hypertension, whereas IL-10 and regulatory T cells are protective. Effector mediators impair nitric oxide bioavailability, leading to endothelial dysfunction and increased vascular contractility. Inflammatory effector mediators also alter renal sodium and water balance and promote renal fibrosis. These mechanisms link hypertension with obesity, autoimmunity, periodontitis and COVID-19. A comprehensive understanding of the immune and inflammatory mechanisms of hypertension is crucial for safely and effectively translating the findings to clinical practice.

Resolvin D2 prevents vascular remodeling, hypercontractility and endothelial dysfunction in obese hypertensive mice through modulation of vascular and proinflammatory factors

During resolution of inflammation, specialized proresolving mediators (SPMs), including resolvins, are produced to restore tissue homeostasis. We hypothesized that there might be a dysregulation of SPMs pathways in pathological vascular remodeling and that resolvin D2 (RvD2) might prevent vascular remodeling and contractile and endothelial dysfunction in a model of obesity and hypertension. In aortic samples of patients with or without abdominal aortic aneurysms (AAA), we evaluated gene expression of enzymes involved in SPMs synthesis (ALOXs), SPMs receptors and pro-inflammatory genes. In an experimental model of aortic dilation induced by high fat diet (HFD, 60%, eighteen weeks) and angiotensin II (AngII) infusion (four weeks), we studied the effect of RvD2 administration in aorta and small mesenteric arteries structure and function and markers of inflammation. In human macrophages we evaluated the effects of AngII and RvD2 in macrophages function and SPMs profile. In patients, we found positive correlations between AAA and obesity, and between AAA and expression of ALOX15, RvD2 receptor GPR18, and pro-inflammatory genes. There was an inverse correlation between the expression of aortic ALOX15 and AAA growth rate. In the mice model, RvD2 partially prevented the HFD plus AngII-induced obesity and adipose tissue inflammation, hypertension, aortic and mesenteric arteries remodeling, hypercontratility and endothelial dysfunction, and the expression of vascular proinflammatory markers and cell apoptosis. In human macrophages, RvD2 prevented AngII-induced impaired efferocytosis and switched SPMs profile. RvD2 might represent a novel protective strategy in preventing vascular damage associated to hypertension and obesity likely through effects in vascular and immune cells.

Role of Treg cell subsets in cardiovascular disease pathogenesis and potential therapeutic targets

In the genesis and progression of cardiovascular diseases involving both innate and adaptive immune responses, inflammation plays a pivotal and dual role. Studies in experimental animals indicate that certain immune responses are protective, while others exacerbate the disease. T-helper (Th) 1 cell immune responses are recognized as key drivers of inflammatory progression in cardiovascular diseases. Consequently, the CD4+CD25+FOXP3+ regulatory T cells (Tregs) are gaining increasing attention for their roles in inflammation and immune regulation. Given the critical role of Tregs in maintaining immune-inflammatory balance and homeostasis, abnormalities in their generation or function might lead to aberrant immune responses, thereby initiating pathological changes. Numerous preclinical studies and clinical trials have unveiled the central role of Tregs in cardiovascular diseases, such as atherosclerosis. Here, we review the roles and mechanisms of Treg subsets in cardiovascular conditions like atherosclerosis, hypertension, myocardial infarction and remodeling, myocarditis, dilated cardiomyopathy, and heart failure. While the precise molecular mechanisms of Tregs in cardiac protection remain elusive, therapeutic strategies targeting Tregs present a promising new direction for the prevention and treatment of cardiovascular diseases.

Myocardial Interstitial Fibrosis in Hypertensive Heart Disease: From Mechanisms to Clinical Management

Hypertensive heart disease (HHD) can no longer be considered as the beneficial adaptive result of the hypertrophy of cardiomyocytes in response to pressure overload leading to the development of left ventricular hypertrophy. The current evidence indicates that in patients with HHD, pathological lesions in the myocardium lead to maladaptive structural remodeling and subsequent alterations in cardiac function, electrical activity, and perfusion, all contributing to poor outcomes. Diffuse myocardial interstitial fibrosis is probably the most critically involved lesion in these disorders. Therefore, in this review, we will focus on the histological characteristics, the mechanisms, and the clinical consequences of myocardial interstitial fibrosis in patients with HHD. In addition, we will consider the most useful tools for the noninvasive diagnosis of myocardial interstitial fibrosis in patients with HHD, as well as the most effective available therapeutic strategies to prevent its development or facilitate its regression in this patient population. Finally, we will issue a call to action for the need for more fundamental and clinical research on myocardial interstitial fibrosis in HHD.

P2RX7 gene knockout or antagonism reduces angiotensin II-induced hypertension, vascular injury and immune cell activation

OBJECTIVE

Extracellular ATP is elevated in hypertensive mice and humans and may trigger immune activation through the purinergic receptor P2X7 (P2RX7) causing interleukin-1β production and T-cell activation and memory T-cell development. Furthermore, P2RX7 single nucleotide polymorphisms (SNP) are associated with hypertension. We hypothesized that P2RX7 activation contributes to hypertension and cardiovascular injury by promoting immune activation.

METHODS

Male wild-type and P2rx7-/- mice were infused or not with angiotensin II (AngII) for 14 days. A second group of AngII-infused wild-type mice were co-infused with the P2RX7 antagonist AZ10606120 or vehicle. BP was monitored by telemetry. Cardiac and mesenteric artery function and remodeling were assessed using ultrasound and pressure myography, respectively. T cells were profiled in thoracic aorta/perivascular adipose tissue by flow cytometry. Associations between SNPs within 50 kb of P2RX7 transcription, and BP or hypertension were modeled in 384 653 UK Biobank participants.

RESULTS

P2rx7 inactivation attenuated AngII-induced SBP elevation, and mesenteric artery dysfunction and remodeling. This was associated with decreased perivascular infiltration of activated and effector memory T-cell subsets. Surprisingly, P2rx7 knockout exaggerated AngII-induced cardiac dysfunction and remodeling. Treatment with a P2RX7 antagonist reduced BP elevation, preserved mesenteric artery function and reduced activated and effector memory T cell perivascular infiltration without adversely affecting cardiac function and remodeling in AngII-infused mice. Three P2RX7 SNPs were associated with increased odds of DBP elevation.

CONCLUSION

P2RX7 may represent a target for attenuating BP elevation and associated vascular damage by decreasing immune activation.

Global, regional, and national burden of hypertensive heart disease among older adults in 204 countries and territories between 1990 and 2019: a trend analysis

BACKGROUND

Hypertensive heart disease (HHD) poses a public health challenge, but data on its burden and trends among older adults are scarce. This study aimed to identify trends in the burden of HHD among older adults between 1990 and 2019 at the global, regional, and national levels.

METHODS

Using the Global Burden of Diseases study 2019 data, we assessed HHD prevalence, death, and disability-adjusted life-year (DALY) rates for individuals aged 60-89 years at the global, regional, and national levels and estimated their average annual percentage changes (AAPCs) between 1990 and 2019 using joinpoint regression analysis.

RESULTS

In 2019, there were 14.35 million HHD prevalent cases, 0.85 million deaths, and 14.56 million DALYs in older adults. Between 1990 and 2019, the prevalence of HHD increased globally {AAPC, 0.38 (95% confidence interval [CI], 0.36, 0.41)} with decreases observed in mortality (AAPC, -0.83 [95% CI, -0.99, -0.66]) and the DALY rate (AAPC, -1.03 [95% CI, -1.19, -0.87]). This overall global trend pattern was essentially maintained for sex, age group, and sociodemographic index (SDI) quintile except for non-significant changes in the prevalence of HHD in those aged 70-74 years and in the middle SDI quintile. Notably, males had a higher HHD prevalence rate. However, HHD-related mortality and the DALY rate were higher in females. The middle SDI quintile experienced the largest decreases in mortality and the DALY rate, with a non-significant decline in prevalence between 1990 and 2019. There were significant discrepancies in the HHD burden and its trends across regions and countries.

CONCLUSIONS

In the past three decades, there has been an overall increasing trend in the prevalence of HHD among older adults worldwide despite decreasing trends in mortality and the DALY rate. Better management of hypertension, and prevention and control of HHD are needed in older adults.

Role of monocytes/macrophages in renin-angiotensin system-induced hypertension and end organ damage

The renin-angiotensin system (RAS) is a central modulator of cardiovascular physiology. Pathophysiology of hypertension is commonly accompanied by hyper-activation of RAS. Angiotensin II receptor blockers (ARBs) and Angiotensin-converting enzyme (ACE) inhibitors are the gold standard treatment for hypertension. Recently, several studies highlighted the crucial role of immune system in hypertension. Angiotensin-II-induced hypertension is associated with low grade inflammation characterized by innate and adaptive immune system dysfunction. Throughout the progression of hypertension, monocyte/macrophage cells appear to have a crucial role in vascular inflammation and interaction with the arterial wall. Since myelomonocytic cells potentially play a key role in angiotensin-II-induced hypertension and organ damage, pharmacological targeting of RAS components in monocyte/macrophages may possibly present an innovative strategy for treatment of hypertension and related pathology.

The importance of microvascular inflammation in ageing and age-related diseases: a position paper from the ESH working group on small arteries, section of microvascular inflammation

Microcirculation is pervasive and orchestrates a profound regulatory cross-talk with the surrounding tissue and organs. Similarly, it is one of the earliest biological systems targeted by environmental stressors and consequently involved in the development and progression of ageing and age-related disease. Microvascular dysfunction, if not targeted, leads to a steady derangement of the phenotype, which cumulates comorbidities and eventually results in a nonrescuable, very high-cardiovascular risk. Along the broad spectrum of pathologies, both shared and distinct molecular pathways and pathophysiological alteration are involved in the disruption of microvascular homeostasis, all pointing to microvascular inflammation as the putative primary culprit. This position paper explores the presence and the detrimental contribution of microvascular inflammation across the whole spectrum of chronic age-related diseases, which characterise the 21st-century healthcare landscape. The manuscript aims to strongly affirm the centrality of microvascular inflammation by recapitulating the current evidence and providing a clear synoptic view of the whole cardiometabolic derangement. Indeed, there is an urgent need for further mechanistic exploration to identify clear, very early or disease-specific molecular targets to provide an effective therapeutic strategy against the otherwise unstoppable rising prevalence of age-related diseases.

Vascular phenotypes in early hypertension

The study characterises vascular phenotypes of hypertensive patients utilising machine learning approaches. Newly diagnosed and treatment-naïve primary hypertensive patients without co-morbidities (aged 18-55, n = 73), and matched normotensive controls (n = 79) were recruited (NCT04015635). Blood pressure (BP) and BP variability were determined using 24 h ambulatory monitoring. Vascular phenotyping included SphygmoCor® measurement of pulse wave velocity (PWV), pulse wave analysis-derived augmentation index (PWA-AIx), and central BP; EndoPAT™-2000® provided reactive hyperaemia index (LnRHI) and augmentation index adjusted to heart rate of 75bpm. Ultrasound was used to analyse flow mediated dilatation and carotid intima-media thickness (CIMT). In addition to standard statistical methods to compare normotensive and hypertensive groups, machine learning techniques including biclustering explored hypertensive phenotypic subgroups. We report that arterial stiffness (PWV, PWA-AIx, EndoPAT-2000-derived AI@75) and central pressures were greater in incident hypertension than normotension. Endothelial function, percent nocturnal dip, and CIMT did not differ between groups. The vascular phenotype of white-coat hypertension imitated sustained hypertension with elevated arterial stiffness and central pressure; masked hypertension demonstrating values similar to normotension. Machine learning revealed three distinct hypertension clusters, representing 'arterially stiffened', 'vaso-protected', and 'non-dipper' patients. Key clustering features were nocturnal- and central-BP, percent dipping, and arterial stiffness measures. We conclude that untreated patients with primary hypertension demonstrate early arterial stiffening rather than endothelial dysfunction or CIMT alterations. Phenotypic heterogeneity in nocturnal and central BP, percent dipping, and arterial stiffness observed early in the course of disease may have implications for risk stratification.

Hypersensitive C-reactive protein as a potential indicator for predicting left ventricular hypertrophy in elderly community-dwelling patients with hypertension

BACKGROUND

The aim of this study was to investigate the relationship between Hypersensitive C-reactive protein (hs-CRP) and left ventricular hypertrophy (LVH) in elderly community-dwelling patients with hypertension.

METHODS

A cross-sectional study was conducted, involving the recruitment of 365 elderly hypertensive residents ≥ 65 years of age from five communities. The participants were divided into two groups: an LVH group (n = 134) and a non-LVH group (n = 231), based on the left ventricular mass index (LVMI) determined by echocardiography. Spearman correlation analysis was used to assess the relationship between hs-CRP and LVH. Univariate and Multivariate analysis was performed to detect variables associated with LVH. The diagnostic value of hs-CRP for LVH was expressed as the area under the receiver operating characteristic (ROC) curve.

RESULTS

The incidence of LVH in elderly hypertension patients in the community was 36.7%. The hs-CRP levels were significantly higher in subjects with LVH compared to those without LVH (1.9 [0.8, 2.9] vs. 0.7 [0.4, 1.4], P = 0.002). Spearman correlation analysis demonstrated a positive correlation between hs-CRP and LVMI (r = 0.246, P < 0.001), as well as with IVST (r = 0.225, P < 0.001) and LVPWT (r = 0.172, P = 0.001). Among elderly hypertensive residents in the community, the cut-off value of hs-CRP for diagnosing LVH was 1.25 mg/L (sensitivity: 57.5%; specificity: 78.4%), and the area under the ROC curve for hs-CRP to predict LVH was 0.710 (95%CI: 0.654-0.766; P < 0.001). In the final model, hs-CRP ≥ 1.25 mg/L (OR = 3.569; 95%CI, 2.153-5.916; P<0.001) emerged as an independent risk factor for LVH. This association remained significant even after adjusting for various confounding factors (adjusted OR = 3.964; 95%CI, 2.323-6.765; P < 0.001).

CONCLUSIONS

This community-based cohort of elderly hypertensive individuals demonstrates a strong association between hs-CRP levels and the presence of LVH. The hs-CRP ≥ 1.25 mg/L may serve as an independent predictor for LVH in hypertensive subjects and exhibit good diagnostic efficacy for LVH.

Inflammation, sex, blood pressure changes and hypertension in midlife: the Hordaland Health Study

Our aim was to test sex-specific associations of circulating markers of inflammation with blood pressure (BP) and incident hypertension in midlife. Participants in the Hordaland Health study (n = 3280, 56% women, mean age 48 years) were examined at baseline and followed for 6 years. Circulating levels of inflammatory markers including high-sensitive C-reactive protein (hs-CRP), neopterin, and pyridoxic acid ratio (PAr) index were measured at follow-up. The associations with systolic/diastolic BP and incident hypertension were tested in sex-specific linear- or logistic-regression analyses adjusted for body mass index, serum triglycerides, creatinine, physical activity, smoking and diabetes. At follow-up, women had lower mean BP than men (124/72 vs. 130/78 mmHg, p < 0.001). Higher hs-CRP was significantly associated with greater systolic and diastolic BP (standardized β = 0.07 and β = 0.09, both p < 0.01) in women, but not in men. Higher neopterin was associated with higher diastolic BP in women and higher PAr index was associated with higher diastolic BP in women and higher systolic and diastolic BP in men (all p < 0.01). Compared to hs-CRP < 1 mg/l, higher levels of hs-CRP 1-<3 mg/l and hs-CRP ≥ 3 mg/l were associated with new-onset hypertension only in women (odds ratio (OR) 1.74, 95% CI 1.20-2.53 and OR 1.87, 95% CI 1.20-2.90). Sex-interactions were found for hs-CRP and neopterin in models on incident hypertension and diastolic BP, respectively (both p < 0.05). Higher levels of circulating markers of inflammation were associated with higher BP and incident hypertension in a sex-specific manner. Our results suggest a sex-specific interaction between cardiovascular inflammation and BP in midlife.

Microcirculation in Hypertension: A Therapeutic Target to Prevent Cardiovascular Disease?

Arterial hypertension is a common condition worldwide and an important risk factor for cardio- and cerebrovascular events, renal diseases, as well as microvascular eye diseases. Established hypertension leads to the chronic vasoconstriction of small arteries as well as to a decreased lumen diameter and the thickening of the arterial media or wall with a consequent increased media-to-lumen ratio (MLR) or wall-to-lumen ratio (WLR). This process, defined as vascular remodeling, was firstly demonstrated in small resistance arteries isolated from subcutaneous biopsies and measured by micromyography, and this is still considered the gold-standard method for the assessment of structural alterations in small resistance arteries; however, microvascular remodeling seems to represent a generalized phenomenon. An increased MLR may impair the organ flow reserve, playing a crucial role in the maintenance and, probably, also in the progressive worsening of hypertensive disease, as well as in the development of hypertension-mediated organ damage and related cardiovascular events, thus possessing a relevant prognostic relevance. New non-invasive techniques, such as scanning laser Doppler flowmetry or adaptive optics, are presently under development, focusing mainly on the evaluation of WLR in retinal arterioles; recently, also retinal microvascular WLR was demonstrated to have a prognostic impact in terms of cardio- and cerebrovascular events. A rarefaction of the capillary network has also been reported in hypertension, which may contribute to flow reduction in and impairment of oxygen delivery to different tissues. These microvascular alterations seem to represent an early step in hypertension-mediated organ damage since they might contribute to microvascular angina, stroke, and renal dysfunction. In addition, they can be markers useful in monitoring the beneficial effects of antihypertensive treatment. Additionally, conductance arteries may be affected by a remodeling process in hypertension, and an interrelationship is present in the structural changes in small and large conductance arteries. The review addresses the possible relations between structural microvascular alterations and hypertension-mediated organ damage, and their potential improvement with antihypertensive treatment.

Obesity, Preserved Ejection Fraction Heart Failure, and Left Ventricular Remodeling

Owing to the overwhelming obesity epidemic, preserved ejection fraction heart failure commonly ensues in patients with severe obesity and the obese phenotype of preserved ejection fraction heart failure is now commonplace in clinical practice. Severe obesity and preserved ejection fraction heart failure share congruent cardiovascular, immune, and renal derangements that make it difficult to ascertain whether the obese phenotype of preserved ejection fraction heart failure is the convergence of two highly prevalent conditions or severe obesity enables the development and progression of the syndrome of preserved ejection fraction heart failure. Nevertheless, the obese phenotype of preserved ejection fraction heart failure provides a unique opportunity to assess whether sustained and sizeable loss of excess body weight via metabolic bariatric surgery reverses the concentric left ventricular remodeling that patients with preserved ejection fraction heart failure commonly display.

Promoting Angiogenesis Using Immune Cells for Tissue-Engineered Vascular Grafts

Implantable tissue-engineered vascular grafts (TEVGs) usually trigger the host reaction which is inextricably linked with the immune system, including blood-material interaction, protein absorption, inflammation, foreign body reaction, and so on. With remarkable progress, the immune response is no longer considered to be entirely harmful to TEVGs, but its therapeutic and impaired effects on angiogenesis and tissue regeneration are parallel. Although the implicated immune mechanisms remain elusive, it is certainly worthwhile to gain detailed knowledge about the function of the individual immune components during angiogenesis and vascular remodeling. This review provides a general overview of immune cells with an emphasis on macrophages in light of the current literature. To the extent possible, we summarize state-of-the-art approaches to immune cell regulation of the vasculature and suggest that future studies are needed to better define the timing of the activity of each cell subpopulation and to further reveal key regulatory switches.

Factors Associating with Non-Dipping Pattern of Nocturnal Blood Pressure in Patients with Essential Hypertension

Background: In patients with essential hypertension, a non-dipping blood pressure pattern is a strong risk factor for cardiovascular diseases. However, background factors associating with such a blood pressure pattern remain unknown. Methods: Untreated essential hypertensive patients without chronic kidney diseases who were admitted to our outpatient clinic were included. Blood sampling and 24 h ambulatory blood pressure monitoring were mandatorily performed. Non-dipper status was defined as a maximum decrease in nocturnal systolic blood pressure within 10%. Clinical factors associating with non-dipper status were investigated. Results: A total of 154 patients (56 ± 12 years old, 86 men) were included. Among baseline characteristics, a higher serum uric acid level was independently associated with non-dipper status (odds ratio 1.03, 95% confidence interval 1.00−1.05, p < 0.05). Among those with non-dipper status, a higher high-sensitivity C-reactive protein level tended to be associated with incremental nighttime systolic blood pressure levels (p = 0.065). Conclusions: Hyperuricemia and micro-inflammation might be associated with attenuated nocturnal blood pressure dipping and incremental nighttime systolic blood pressure levels.

Role of inflammation, immunity, and oxidative stress in hypertension: New insights and potential therapeutic targets

Hypertension is regarded as the most prominent risk factor for cardiovascular diseases, which have become a primary cause of death, and recent research has demonstrated that chronic inflammation is involved in the pathogenesis of hypertension. Both innate and adaptive immunity are now known to promote the elevation of blood pressure by triggering vascular inflammation and microvascular remodeling. For example, as an important part of innate immune system, classically activated macrophages (M1), neutrophils, and dendritic cells contribute to hypertension by secreting inflammatory cy3tokines. In particular, interferon-gamma (IFN-γ) and interleukin-17 (IL-17) produced by activated T lymphocytes contribute to hypertension by inducing oxidative stress injury and endothelial dysfunction. However, the regulatory T cells and alternatively activated macrophages (M2) may have a protective role in hypertension. Although inflammation is related to hypertension, the exact mechanisms are complex and unclear. The present review aims to reveal the roles of inflammation, immunity, and oxidative stress in the initiation and evolution of hypertension. We envisage that the review will strengthen public understanding of the pathophysiological mechanisms of hypertension and may provide new insights and potential therapeutic strategies for hypertension.

State of the Art Review: Vascular Remodeling in Hypertension

Although the gold-standard method for the assessment of structural alteration in small resistance arteries is the evaluation of the MLR by micromyography in bioptic tissues, new, noninvasive techniques are presently under development, focusing mainly on the evaluation of WLR in retinal arterioles. These approaches represent a promising and interesting future perspective. Appropriate antihypertensive treatment is able to prevent the development of microvascular alterations or to induce their regression. Also, conductance arteries may be affected by a remodeling process in hypertension, and a cross-talk may exist between structural changes in the small and large arteries. In conclusion, the evaluation of microvascular structure is ready for clinical prime time, and it could, in the future, represent an evaluation to be performed in the majority of hypertensive patients, to better stratify cardiovascular risk and better evaluate the effects of antihypertensive therapy. However, for this purpose, we need a clear demonstration of the prognostic relevance of noninvasive measures of microvascular structure, in basal conditions and during treatment. Vascular remodeling may be frequently observed in hypertension, as well as in obesity and diabetes mellitus. An increased media to lumen ratio (MLR) or wall to lumen ratio (WLR) in microvessels is the hallmark of hypertension, and may impair organ flow reserve, being relevant in the maintenance and, probably, also in the progressive worsening of hypertensive disease, as well as in the development of hypertension-mediated organ damage/cardiovascular events. The molecular mechanisms underlying the development of vascular remodeling are only partly understood.

Growing Heart Failure Burden of Hypertensive Heart Disease: A Call to Action

Hypertensive heart disease (HHD) is currently the second leading cause of heart failure. The prevalence of HHD and its associated risk of heart failure have increased despite substantial improvement in arterial hypertension treatment and control in the recent decades. Therefore, the prevention of heart failure in patients with HHD represents an unmet medical need, due to its clinical, economic, and social impact. In this conceptual framework, we call to action because the time has come for diagnosis and treatment of patients with HHD not to be limited to assessment of morphological and functional left ventricular changes, blood pressure control, and left ventricular hypertrophy regression. We propose a further perspective incorporating also the detection and reversal of the histological changes that develop in the hypertensive heart and that lead to the structural remodeling of the myocardium. In particular, we focus on the diagnosis and treatment of myocardial interstitial fibrosis, likely the lesion most critically involved in the transition from subclinical HHD to clinically overt heart failure. In this context, it is worth considering whether the use of imaging and circulating biomarkers for the noninvasive diagnosis of myocardial interstitial fibrosis should be incorporated in the medical study of hypertensive patients, especially of those with HHD.

Hypoxia-induced endothelial cell-derived exosome stimulates vascular smooth muscle cell proliferation and migration

This study mainly used human VSMCs and ECs cultured in vitro to investigate whether exosomes (Exos) are involved in the communication between ECs and VSMCs under hypoxia, and to explore the role and mechanism of ECs-derived exosomes in the abnormal proliferation of VSMCs. VSMCs proliferation and migration were assessed by a series of cell function assays after culturing VSMCs alone or co-culturing ECs under hypoxia or normoxia. Next, exosomes were extracted from ECs under hypoxia or normoxia and characterized. We then introduced ECs-Exos to observe their effects on VSMCs proliferation and migration, and further evaluated the expression of transforming growth factor-beta receptor 1 (TGFBR1) pathway-related proteins. Finally, the effect of ECs-Exos on VSMCs function was evaluated after knocking down TGFBR1 in ECs. VSMCs treated with ECs-Exos exhibited increased proliferation and migration ability in hypoxic environment, and the expression of TGFBR1 pathway-related proteins was upregulated. Administration of ECs-Exos with TGFβ1 knockdown conspicuously reversed the promoting effects of ECs-Exos on cell proliferation and migration under hypoxia. In summary, hypoxia affected the secretion of extracellular vesicles by endothelial cells, which can be internalized by VSMCs and accelerate the abnormal proliferation and migration of VSMCs by delivering TGFBR1.

The Role of N6-Methyladenosine Modification in Microvascular Dysfunction

Microvascular dysfunction (MVD) has long plagued the medical field despite improvements in its prevention, diagnosis, and intervention. Microvascular lesions from MVD increase with age and further lead to impaired microcirculation, target organ dysfunction, and a mass of microvascular complications, thus contributing to a heavy medical burden and rising disability rates. An up-to-date understanding of molecular mechanisms underlying MVD will facilitate discoveries of more effective therapeutic strategies. Recent advances in epigenetics have revealed that RNA methylation, an epigenetic modification, has a pivotal role in vascular events. The N⁶-methylation of adenosine (m⁶A) modification is the most prevalent internal RNA modification in eukaryotic cells, which regulates vascular transcripts through splicing, degradation, translation, as well as translocation, thus maintaining microvascular homeostasis. Conversely, the disruption of the m⁶A regulatory network will lead to MVD. Herein, we provide a review discussing how m⁶A methylation interacts with MVD. We also focus on alterations of the m⁶A regulatory network under pathological conditions. Finally, we highlight the value of m⁶A regulators as prognostic biomarkers and novel therapeutic targets, which might be a promising addition to clinical medicine.

Genetic Modifications to Alter Blood Pressure Level

Genetic manipulation is one of the indispensable techniques to examine gene functions both in vitro and in vivo. In particular, cardiovascular phenotypes such as blood pressure cannot be evaluated in vitro system, necessitating the creation of transgenic or gene-targeted knock-out and knock-in experimental animals to understand the pathophysiological roles of specific genes on the disease conditions. Although genome-wide association studies (GWAS) in various human populations have identified multiple genetic variations associated with increased risk for hypertension and/or its complications, the causal links remain unresolved. Genome-editing technologies can be applied to many different types of cells and organisms for creation of knock-out/knock-in models. In the post-GWAS era, it may be more worthwhile to validate pathophysiological implications of the risk variants and/or candidate genes by creating genome-edited organisms.

Supplementation with the Symbiotic Formulation Prodefen® Increases Neuronal Nitric Oxide Synthase and Decreases Oxidative Stress in Superior Mesenteric Artery from Spontaneously Hypertensive Rats

In recent years, gut dysbiosis has been related to some peripheral vascular alterations linked to hypertension. In this work, we explore whether gut dysbiosis is related to vascular innervation dysfunction and altered nitric oxide (NO) production in the superior mesenteric artery, one of the main vascular beds involved in peripheral vascular resistance. For this purpose, we used spontaneously hypertensive rats, either treated or not with the commercial synbiotic formulation Prodefen^® (10⁸ colony forming units/day, 4 weeks). Prodefen^® diminished systolic blood pressure and serum endotoxin, as well as the vasoconstriction elicited by electrical field stimulation (EFS), and enhanced acetic and butyric acid in fecal samples, and the vasodilation induced by the exogenous NO donor DEA-NO. Unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in rats supplemented with Prodefen^®. Both neuronal NO release and neuronal NOS activity were enhanced by Prodefen^®, through a hyperactivation of protein kinase (PK)A, PKC and phosphatidylinositol 3 kinase-AKT signaling pathways. The superoxide anion scavenger tempol increased both NO release and DEA-NO vasodilation only in control animals. Prodefen^® caused an increase in both nuclear erythroid related factor 2 and superoxide dismutase activities, consequently reducing both superoxide anion and peroxynitrite releases. In summary, Prodefen^® could be an interesting non-pharmacological approach to ameliorate hypertension.