Regulatory T-cell subset distribution in children with primary hypertension is associated with hypertension severity and hypertensive target organ damage

Resolution of inflammation, an active process to restore the immune microenvironment balance: A novel drug target for treating arterial hypertension

The resolution of inflammation, the other side of the inflammatory response, is defined as an active and highly coordinated process that promotes the restoration of immune microenvironment balance and tissue repair. Inflammation resolution involves several key processes, including dampening proinflammatory signaling, specialized proresolving lipid mediator (SPM) production, nonlipid proresolving mediator production, efferocytosis and regulatory T-cell (Treg) induction. In recent years, increasing attention has been given to the effects of inflammation resolution on hypertension. Furthermore, our previous studies reported the antihypertensive effects of SPMs. Therefore, in this review, we aim to summarize and discuss the detailed association between arterial hypertension and inflammation resolution. Additional, the association between gut microbe-mediated immune and hypertension is discussed. This findings suggested that accelerating the resolution of inflammation can have beneficial effects on hypertension and its related organ damage. Exploring novel drug targets by focusing on various pathways involved in accelerating inflammation resolution will contribute to the treatment and control of hypertensive diseases in the future.

Pathophysiology of primary hypertension in children and adolescents

The progress in research on the physiology of the cardiovascular system made in the last 100 years allowed for the development of the pathogenesis not only of secondary forms of hypertension but also of primary hypertension. The main determinants of blood pressure are described by the relationship between stroke volume, heart rate, peripheral resistance, and arterial stiffness. The theories developed by Guyton and Folkow describe the importance of the volume factor and total peripheral resistance. However, none of them fully presents the pathogenesis of essential hypertension. The multifactorial model of primary hypertension pathogenesis developed by Irving Page in the 1940s, called Page's mosaic, covers most of the pathophysiological phenomena observed in essential hypertension. The most important pathophysiological phenomena included in Page's mosaic form a network of interconnected "nodes". New discoveries both from experimental and clinical studies made in recent decades have allowed the original Page mosaic to be modified and the addition of new pathophysiological nodes. Most of the clinical studies confirming the validity of the multifactorial pathogenesis of primary hypertension concern adults. However, hypertension develops in childhood and is even perinatally programmed. Therefore, the next nodes in Page's mosaic should be age and perinatal factors. This article presents data from pediatric clinical trials describing the most important pathophysiological processes associated with the development of essential hypertension in children and adolescents.

Subpopulations of regulatory T cells are associated with subclinical atherosclerotic plaques, levels of LDL, and cardiorespiratory fitness in the elderly

BACKGROUND

Atherosclerosis forms the pathological basis for the development of cardiovascular disease. Since pathological processes initially develop without clinically relevant symptoms, the identification of early markers in the subclinical stage plays an important role for initiating early interventions. There is evidence that regulatory T cells (Tregs) are involved in the development of atherosclerosis. Therefore, the present study aimed to identify and investigate associations with Tregs and their subsets in a cohort of healthy elderly individuals with and without subclinical atherosclerotic plaques (SAP). In addition, various lifestyle and risk factors, such as cardiorespiratory fitness, were investigated as associated signatures.

METHODS

A cross-sectional study was performed in 79 participants (male: n = 50; age = 63.6 ± 3.7 years; body mass index = 24.9 ± 3.1 kg/m²; mean ± SD) who had no previous diagnosis of chronic disease and were not taking medication. Ultrasound of the carotids to identify SAP, cardiovascular function measurement for vascular assessment and a cardiorespiratory fitness test to determine peak oxygen uptake were performed. Additionally, tests were conducted to assess blood lipids and determine glucose levels. Immunophenotyping of Tregs and their subtypes (resting (rTregs) and effector/memory (mTregs)) was performed by 8-chanel flow cytometry. Participants were categorized according to atherosclerotic plaque status. Linear and logistic regression models were used to analyze associations between parameters.

RESULTS

SAP was detected in a total of 29 participants. The participants with plaque were older (64.8 ± 3.6 years vs. 62.9 ± 3.5 years) and had higher peripheral systolic blood pressure (133.8 ± 14.7 mmHg vs. 125.8 ± 10.9 mmHg). The participants with SAP were characterized by a lower percentage of rTregs (28.8% ± 10.7% vs. 34.6% ± 10.7%) and a higher percentage of mTregs (40.3% ± 14.7% vs. 30.0% ± 11.9%). Multiple logistic regression identified age (odds ratio (OR) = 1.20 (95% confidence interval (95%CI): 1.01-1.42)) and mTregs (OR = 1.05 (95%CI: 1.02-1.10)) as independent risk factors for SAP. Stepwise linear regression could reveal an association of peak oxygen uptake (β = 0.441), low-density lipoprotein (LDL) (β = -0.096), and SAP (β = 6.733) with mTregs and LDL (β = 0.104) with rTregs.

CONCLUSION

While at an early stage of SAP, the total proportion of Tregs gives no indication of vascular changes, this is indicated by a shift in the Treg subgroups. Factors such as serum LDL or cardiopulmonary fitness may be associated with this shift and may also be additional diagnostic indicators. This could be used to initiate lifestyle-based preventive measures at an early stage, which may have a protective effect against disease progression.

Immune mechanisms in the pathophysiology of hypertension

Hypertension is a leading risk factor for morbidity and mortality worldwide. Despite current anti-hypertensive therapies, most individuals with hypertension fail to achieve adequate blood pressure control. Moreover, even with adequate control, a residual risk of cardiovascular events and associated organ damage remains. These findings suggest that current treatment modalities are not addressing a key element of the underlying pathology. Emerging evidence implicates immune cells as key mediators in the development and progression of hypertension. In this Review, we discuss our current understanding of the diverse roles of innate and adaptive immune cells in hypertension, highlighting key findings from human and rodent studies. We explore mechanisms by which these immune cells promote hypertensive pathophysiology, shedding light on their multifaceted involvement. In addition, we highlight advances in our understanding of autoimmunity, HIV and immune checkpoints that provide valuable insight into mechanisms of chronic and dysregulated inflammation in hypertension.

Etiology, risk factors and management of hypertension post liver transplantation

BACKGROUND

Cardiovascular events are one of the most important causes of morbidity and mortality in the long-term follow-up of liver transplant recipients. Hypertension is a significant cardiovascular risk factor that occurs frequently after pediatric liver transplantation. Chronic use of immunosuppressants - mainly calcineurin inhibitors - plays a major role in the development of post-transplant hypertension and circadian disturbances such as flattening of the nocturnal blood pressure dip. This requires special attention in children given the long timeframe during which immunosuppressive therapy is necessary. Careful and structured blood pressure monitoring and adequate treatment of hypertension are essential to optimize the quality of life and life expectancy of pediatric liver transplant patients. However, evidence-based guidelines for monitoring and management of post-transplant hypertension and its complications are lacking.

METHODS

We conducted a comprehensive review of the current knowledge and practices concerning post-transplant hypertension. The databases Pubmed, Embase, Web of Science and Google Scholar were scanned with the following keywords: pediatric liver transplantation, immunosuppression, tacrolimus, cardiovascular effects, hypertension, heart function, kidney function, circadian rhythm, mechanism, monitoring, and management.

RESULTS

In this review, we describe the incidence and etiology of hypertension in pediatric liver transplant recipients, the underlying mechanisms and characteristics of calcineurin inhibitor-induced hypertension, and the consequences of and risk factors for post-transplant hypertension. We hereby present an overview of the current practices in blood pressure monitoring and antihypertensive treatment as well as an algorithm for the evaluation and management of hypertension post liver transplantation. Finally, we discuss knowledge gaps and suggestions for future research.

CD4+ T-Cell Legumain Deficiency Attenuates Hypertensive Damage via Preservation of TRAF6

BACKGROUND

T cells are central to the immune responses contributing to hypertension. LGMN (legumain) is highly expressed in T cells; however, its role in the pathogenesis of hypertension remains unclear.

METHODS

Peripheral blood samples were collected from patients with hypertension, and cluster of differentiation (CD)4+ T cells were sorted for gene expression and Western blotting analysis. TLGMNKO (T cell-specific LGMN-knockout) mice (Lgmnf/f/CD4Cre), regulatory T cell (Treg)-specific LGMN-knockout mice (Lgmnf/f/Foxp3YFP Cre), and RR-11a (LGMN inhibitor)-treated C57BL/6 mice were infused with Ang II (angiotensin II) or deoxycorticosterone acetate/salt to establish hypertensive animal models. Flow cytometry, 4-dimensional label-free proteomics, coimmunoprecipitation, Treg suppression, and in vivo Treg depletion or adoptive transfer were used to delineate the functional importance of T-cell LGMN in hypertension development.

RESULTS

LGMN mRNA expression was increased in CD4+ T cells isolated from hypertensive patients and mice, was positively correlated with both systolic and diastolic blood pressure, and was negatively correlated with serum IL (interleukin)-10 levels. TLGMNKO mice exhibited reduced Ang II-induced or deoxycorticosterone acetate/salt-induced hypertension and target organ damage relative to wild-type (WT) mice. Genetic and pharmacological inhibition of LGMN blocked Ang II-induced or deoxycorticosterone acetate/salt-induced immunoinhibitory Treg reduction in the kidneys and blood. Anti-CD25 antibody depletion of Tregs abolished the protective effects against Ang II-induced hypertension in TLGMNKO mice, and LGMN deletion in Tregs prevented Ang II-induced hypertension in mice. Mechanistically, endogenous LGMN impaired Treg differentiation and function by directly interacting with and facilitating the degradation of TRAF6 (tumor necrosis factor receptor-associated factor 6) via chaperone-mediated autophagy, thereby inhibiting NF-κB (nuclear factor kappa B) activation. Adoptive transfer of LGMN-deficient Tregs reversed Ang II-induced hypertension, whereas depletion of TRAF6 in LGMN-deficient Tregs blocked the protective effects.

CONCLUSIONS

LGMN deficiency in T cells prevents hypertension and its complications by promoting Treg differentiation and function. Specifically targeting LGMN in Tregs may be an innovative approach for hypertension treatment.

Regulatory T cells and cardiovascular diseases

ABSTRACT

Inflammation is a major underlying mechanism in the progression of numerous cardiovascular diseases (CVDs). Regulatory T cells (Tregs) are typical immune regulatory cells with recognized immunosuppressive properties. Despite the immunosuppressive properties, researchers have acknowledged the significance of Tregs in maintaining tissue homeostasis and facilitating repair/regeneration. Previous studies unveiled the heterogeneity of Tregs in the heart and aorta, which expanded in CVDs with unique transcriptional phenotypes and reparative/regenerative function. This review briefly summarizes the functional principles of Tregs, also including the synergistic effect of Tregs and other immune cells in CVDs. We discriminate the roles and therapeutic potential of Tregs in CVDs such as atherosclerosis, hypertension, abdominal arterial aneurysm, pulmonary arterial hypertension, Kawasaki disease, myocarditis, myocardial infarction, and heart failure. Tregs not only exert anti-inflammatory effects but also actively promote myocardial regeneration and vascular repair, maintaining the stability of the local microenvironment. Given that the specific mechanism of Tregs functioning in CVDs remains unclear, we reviewed previous clinical and basic studies and the latest findings on the function and mechanism of Tregs in CVDs.

Modulating T Cell Phenotype and Function to Treat Hypertension

Hypertension is the leading modifiable risk factor of worldwide morbidity and mortality because of its effects on cardiovascular and renal end-organ damage. Unfortunately, BP control is not sufficient to fully reduce the risks of hypertension, underscoring the need for novel therapies that address end-organ damage in hypertension. Over the past several decades, the link between immune activation and hypertension has been well established, but there are still no therapies for hypertension that specifically target the immune system. In this review, we describe the critical role played by T cells in hypertension and hypertensive end-organ damage and outline potential therapeutic targets to modulate T-cell phenotype and function in hypertension without causing global immunosuppression.

Immune Profiling Reveals Decreases in Circulating Regulatory and Exhausted T Cells in Human Hypertension

Evidence from nonhuman animal models demonstrates an important role for immune cells in hypertension, but immune cell changes in human hypertension are less clear. Using mass cytometry, we demonstrate novel and selective reductions in CCR10+ regulatory T cells (Tregs) and PD-1+CD57-CD8+ memory T cells. RNA sequencing reveals that CCR10+ Tregs exhibit gene expression changes consistent with enhanced immunosuppressive function. In addition, CITE-Seq demonstrates that PD-1+CD57-CD8+ memory T cells exhibit features of T-cell exhaustion. Taken together, these results provide novel evidence for decreases in anti-inflammatory and/or hypofunctional T-cell populations that may contribute to enhanced inflammation in human hypertension.

Naïve-memory regulatory T cells ratio is a prognostic biomarker for patients with acute ischemic stroke

Background

Regulatory T cells (Treg) have been identified as a key modulator of neuroinflammation in stroke. However, little is known about the association of Treg subpopulations with clinical outcome in patients with acute ischemic stroke (AIS).

Methods

Patients within 1 week from stroke onset were prospectively enrolled in this study. Healthy controls were sex-and age-matched 1:1 to AIS patients. The frequencies of Treg and Treg subsets were analyzed by flow cytometry and compared with nonstroke control. Univariate and multivariate logistic regression analysis was performed to investigate the prognostic value of Treg subsets in stroke outcomes.

Results

A total of 328 patients and 328 controls were included in the study. Compared with controls, patients with AIS had higher levels of Treg frequency and memory Treg (mTreg) frequency, but lower levels of naïve Treg (nTreg) frequency and nTreg/mTreg ratio. One hundred twenty-six (38.4%) patients experienced unfavorable outcome (modified Rankin score 2-6). Multivariate regression analysis showed that nTreg/mTreg ratio was negatively associated with unfavorable 90-day outcome (the highest tertile versus the lowest tertile: odds ratio 0.13, 95% confidential interval [CI] 0.05-0.35). The risk estimation of unfavorable 90 day outcome can be significantly improved by adding nTreg/mTreg ratio to the conventional clinical parameters (continuous net reclassification improvement 91.26, 95% CI 69.04-113.5%, p < 0.001; integrated discrimination improvement 22.38, 95% CI 17.16-27.59%, p < 0.001).

Conclusion

This study showed that patients with AIS had elevated Treg frequency and mTreg frequency, but reduced nTreg frequency and nTreg/mTreg ratio. Admission nTreg/mTreg ratio was an independent predictor of unfavorable 90 day outcome in AIS. However, large sample-size cohort studies are needed to confirm our findings.

Accelerated vascular age in adolescents with primary hypertension

BACKGROUND

Primary hypertension may lead to early vascular ageing. We aimed to evaluate differences between expected vascular age based on pulse wave velocity (PWV)/carotid intima-media thickness (cIMT) and actual chronological age (CHA) in adolescents with primary hypertension.

METHODS

Three hundred and fifty-two children (median age of 15.5 years) with office hypertension and 64 normotensive healthy children of the same age underwent anthropometry, office and ambulatory blood pressure (BP), left ventricular mass index, cIMT, PWV, pulse wave analysis and biochemistry measurements. Vascular age was calculated using pooled pediatric and adult normative PWV and cIMT data. The difference between vascular age and CHA was calculated in relation to the 90th percentile for PWV (PWVAgeDiff90) and the 95th percentile for cIMT (cIMTAgeDiff95).

RESULTS

One hundred and sixty-six patients had white-coat hypertension (WCH), 32 had ambulatory prehypertension (AmbPreHT), 55 had isolated systolic hypertension with normal central SBP (ISH+cSBPn), 99 had elevated office, ambulatory and cSBP (true hypertension, tHT). The differences between vascular age (both PWV and cIMT based) and CHA were significantly higher in AmbPreHT and tHT compared with normotension, WCH and ISH+cSBPn. Median PWVAgeDidff90 was -3.2, -1.2, -2.1, +0.8 and +0.3 years in normotension, WCH, ISH+cSBPn, AmbPreHT and tHT, respectively. Median cIMTAgeDiff95 was -8.0, -6.3, -6.8, -3.8 and -4.3 years in normotension, WCH, ISH+cSBPn, AmbPreHT and tHT, respectively. Significant predictors of PWVAge90Diff were the DBP and serum cholesterol, whereas cSBP and augmentation index were significant predictors of cIMTAgeDiff95.

CONCLUSION

Children with AmbPreHT and tHT show accelerated vascular age compared with their normotensive peers.

O-Linked β-N-Acetylglucosamine Modification: Linking Hypertension and the Immune System

The O-linked β-N-acetylglucosamine modification (O-GlcNAcylation) of proteins dynamically regulates protein function, localization, stability, and interactions. This post-translational modification is intimately linked to cardiovascular disease, including hypertension. An increasing number of studies suggest that components of innate and adaptive immunity, active players in the pathophysiology of hypertension, are targets for O-GlcNAcylation. In this review, we highlight the potential roles of O-GlcNAcylation in the immune system and discuss how those immune targets of O-GlcNAcylation may contribute to arterial hypertension.

Distribution and maturation state of peripheral blood dendritic cells in children with primary hypertension

Dendritic cells (DCs) play an important role in T cell alterations in primary hypertension (PH). We determined the numbers and maturation markers of peripheral blood total DCs (tDCs), myeloid cells (mDCs), and plasmacytoid cells (pDCs) and their association with hypertension-mediated organ damage (HMOD) markers and selected immune parameters in 30 adolescents with white coat hypertension (WCH), 25 adolescents with PH and a group of 35 age- and sex-matched children with normotension. Using multicolor flow cytometry, expression of maturation markers (CD86 and CD83) in tDCs (Lin1^-/HLA-DR⁺), myeloid DCs (Lin1^-/HLA-DR⁺/CD11c⁺) (mDCs), and plasmacytoid DCs (Lin1^-/HLA-DR⁺/CD123⁺) (pDCs) and the distribution of peripheral Th17-bearing and T-reg cells were defined. In subjects with hypertension, carotid intima-media thickness (cIMT), left ventricular mass index (LVMI), and pulse wave velocity (PWV) were assessed. Compared with WCH and subjects with normotension, subjects with hypertension had reduced tDC and pDC numbers, an increased percentage of mDC subsets, an elevated mDC/pDC ratio, an increased population of mature mDC and pDC subsets bearing CD83 of high density, a decreased subset of CD86-bearing pDCs, and increased expression of DC activation markers (HLA-DR, CD86), as well as CD11c (mDCs) and CD123 (pDCs). PWV, LVMI, and cIMT values correlated negatively with tDCs and pDCs and positively with mDC numbers. Expression of DC maturation/activation markers (CD83, CD86, HLA-DR, CD11c, and CD123) correlated positively with PWV. Certain DC characteristics of WCH subjects resembled those of PH subjects (decreased tDC frequency and upregulation of activation marker expression). These changes correlated with HMOD. WCH subjects presented a DC phenotype that was intermediate between the normotensive and hypertensive phenotypes.

Hypertension: Do Inflammation and Immunity Hold the Key to Solving this Epidemic?

Elevated cardiovascular risk including stroke, heart failure, and heart attack is present even after normalization of blood pressure in patients with hypertension. Underlying immune cell activation is a likely culprit. Although immune cells are important for protection against invading pathogens, their chronic overactivation may lead to tissue damage and high blood pressure. Triggers that may initiate immune activation include viral infections, autoimmunity, and lifestyle factors such as excess dietary salt. These conditions activate the immune system either directly or through their impact on the gut microbiome, which ultimately produces chronic inflammation and hypertension. T cells are central to the immune responses contributing to hypertension. They are activated in part by binding specific antigens that are presented in major histocompatibility complex molecules on professional antigen-presenting cells, and they generate repertoires of rearranged T-cell receptors. Activated T cells infiltrate tissues and produce cytokines including interleukin 17A, which promote renal and vascular dysfunction and end-organ damage leading to hypertension. In this comprehensive review, we highlight environmental, genetic, and microbial associated mechanisms contributing to both innate and adaptive immune cell activation leading to hypertension. Targeting the underlying chronic immune cell activation in hypertension has the potential to mitigate the excess cardiovascular risk associated with this common and deadly disease.

Promoting cardiovascular health post-transplant through early diagnosis and adequate management of hypertension and dyslipidemia

Despite correction of underlying solid organ failure by transplantation, pediatric transplant recipients still have increased mortality rates compared to the general pediatric population, in part due to increased cardiovascular risk. In particular, pediatric kidney and non-kidney transplant recipients with chronic kidney disease have significant cardiovascular risk that worsens with declining kidney function. Biomarkers associated with future cardiovascular risk such as casual and ambulatory hypertension, dyslipidemia, vascular stiffness and calcification, and left ventricular hypertrophy can be detected throughout the post-transplant period and in patients with stable kidney function. Among these, hypertension and dyslipidemia are two potentially modifiable cardiovascular risk factors that are highly prevalent in kidney and non-kidney pediatric transplant recipients. Standardized approaches to appropriate BP measurement and lipid monitoring are needed to detect and address these risk factors in a timely fashion. To achieve sustained improvement in cardiovascular health, clinicians should partner with patients and their caregivers to address these and other risk factors with a combined approach that integrates pharmacologic with non-pharmacologic approaches. This review outlines the scope and impact of hypertension and dyslipidemia in pediatric transplant recipients, with a particular focus on pediatric kidney transplantation given the high burden of chronic kidney disease-associated cardiovascular risk. We also review the current published guidelines for monitoring and managing abnormalities in blood pressure and lipids, highlighting the important role of therapeutic lifestyle changes in concert with antihypertensive and lipid-lowering medications.

Obesity, metabolic syndrome, and primary hypertension

Primary hypertension is the dominant form of arterial hypertension in adolescents. Disturbed body composition with, among other things, increased visceral fat deposition, accelerated biological maturation, metabolic abnormalities typical for metabolic syndrome, and increased adrenergic drive constitutes the intermediary phenotype of primary hypertension. Metabolic syndrome is observed in 15-20% of adolescents with primary hypertension. These features are also typical of obesity-related hypertension. Metabolic abnormalities and metabolic syndrome are closely associated with both the severity of hypertension and the risk of target organ damage. However, even though increased body mass index is the main determinant of blood pressure in the general population, not every hypertensive adolescent is obese and not every obese patient suffers from hypertension or metabolic abnormalities typical for metabolic syndrome. Thus, the concepts of metabolically healthy obesity, normal weight metabolically unhealthy, and metabolically unhealthy obese phenotypes have been developed. The risk of hypertension and hypertensive target organ damage increases with exposure to metabolic risk factors which are determined by disturbed body composition and visceral obesity. Due to the fact that both primary hypertension and obesity-related hypertension present similar pathogenesis, the principles of treatment are the same and are focused not only on lowering blood pressure, but also on normalizing body composition and metabolic abnormalities.

Origins of Primary Hypertension in Children

Although relatively rare in childhood, primary hypertension (PH) is thought to have originated in childhood and may be even determined perinatally. PH prevalence increases in school-age children and affects 11% of 18-year-old adolescents. Associated with metabolic risk factors, elevated blood pressure in childhood is carried into adulthood. Analysis of the phenotype of hypertensive children has revealed that PH is a complex of anthropometric and neuro-immuno-metabolic abnormalities, typically found in hypertensive adults. Children with elevated blood pressure have shown signs of accelerated biological development, which are closely associated with further development of PH, metabolic syndrome, and cardiovascular disease in adulthood. At the time of diagnosis, hypertensive children were reported to have significant arterial remodelling expressed as significantly increased carotid intima-media thickness, increased stiffness of large arteries, lower area of microcirculation, and decreased endothelial function. These changes indicate that their biological age is 4 to 5 years older than their normotensive peers. All these abnormalities are typical features of early vascular aging described in adults with PH. However, as these early vascular changes in hypertensive children are closely associated with features of accelerated biological development and neuro-immuno-metabolic abnormalities observed in older subjects, it seems that PH in childhood is not only an early vascular aging event, but also an early biological maturation phenomenon.