T lymphocytes and vascular inflammation contribute to stress-dependent hypertension

Neuroimmune crosstalk : How mental stress fuels vascular inflammation

Cardiovascular diseases are the leading cause of death worldwide. Pathophysiologically, metabolic and inflammatory processes contribute substantially to the development and progression of cardiovascular diseases. Over the past decade, the role of disease-propagating inflammatory processes has been strengthened and reframed, leading to trials testing anti-inflammatory drugs for the treatment of atherosclerosis and its complications. Despite these achievements, further research in both pre-clinical and clinical studies is warranted to explore new targets, to better identify responders, and to refine therapy strategies to combat inflammation in human disease. Environmental disturbances, so-called lifestyle-associated cardiovascular risk factors, greatly alter the immune system in general and leukocytes in particular, thus affecting the progression of atherosclerosis. Epidemiological studies have shown that exposure to mental stress can be closely linked to the occurrence of cardiovascular disease. Here, we describe how acute and chronic mental stress alter the immune system via neuroimmune interactions, thereby modifying vascular inflammation. In addition, we identify gaps that still need to be addressed in the future.

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.

Effects of lifestyle factors on leukocytes in cardiovascular health and disease

Exercise, stress, sleep and diet are four distinct but intertwined lifestyle factors that influence the cardiovascular system. Abundant epidemiological, clinical and preclinical studies have underscored the importance of managing stress, having good sleep hygiene and responsible eating habits and exercising regularly. We are born with a genetic blueprint that can protect us against or predispose us to a particular disease. However, lifestyle factors build upon and profoundly influence those predispositions. Studies in the past 10 years have shown that the immune system in general and leukocytes in particular are particularly susceptible to environmental perturbations. Lifestyle factors such as stress, sleep, diet and exercise affect leukocyte behaviour and function and thus the immune system at large. In this Review, we explore the various mechanisms by which lifestyle factors modulate haematopoiesis and leukocyte migration and function in the context of cardiovascular health. We pay particular attention to the role of the nervous system as the key executor that connects environmental influences to leukocyte behaviour.

RUPP Th17s cause hypertension and mitochondrial dysfunction in the kidney and placenta during pregnancy

BACKGROUND

Preeclampsia (PE), new-onset hypertension (HTN), and organ dysfunction during the second half of pregnancy, is associated with an increase in inflammatory immune cells, including T helper 17 (Th17) cells. Studies have demonstrated that mitochondrial (mt) dysfunction is important in the pathogenesis of PE though causative factors have yet to be fully identified. Although Th17 cells, natural killer (NK) cells, and mt dysfunction contribute to HTN in the reduced uterine perfusion pressure (RUPP) rat model, the role of Th17 cells or IL-17 in mt dysfunction is unknown. Therefore, we hypothesize that RUPP stimulated Th17 cells cause HTN and mt dysfunction, which is alleviated with the blockade of IL-17.

METHODS

On gestational day 12 (GD12), RUPP Th17 cells were transferred into normal pregnant (NP) Sprague Dawley rats. A subset of NP + RUPPTh17 rats received IL-17RC (100 pg/day) on GD14-19. Blood pressure (MAP), NK cells, and mt function were measured on GD19 in all groups.

RESULTS

MAP increased in response to NP + RUPP Th17 compared to NP rats and was lowered with IL-17RC. Circulating and placental NK cells increased with NP + RUPP Th17 compared to NP and were lowered with IL-17RC. Renal mtROS increased in NP + RUPP Th17 compared to NP and was normalized with IL-17RC. Similar to PE women, placental mtROS decreased in NP + RUPP Th17 and was normalized with IL-17RC.

CONCLUSION

Our results indicate that IL-17RC inhibition normalizes HTN, NK cell activation, and multi-organ mt dysfunction caused by Th17 cells stimulated in response to placental ischemia.

Microbial bowel infections-induced biochemical and biological abnormalities and their effects on young Egyptian swimmers

Swimmers' personal hygiene affects the spread of microbes in pools. The present study aimed to determine the incidence of microbial infections among young Egyptian swimmers and its impact on swimmers' scores. From January 2020 to June 2021, 528 public club swimmers were examined cross-sectionally. Swimmers were divided into two groups according to their star tests and their scores in the competition (group 1 with a high score and group 2 with a low score). Stool samples, biochemical and biological parameters were assessed. Microbial infections were 54% for intestinal parasitosis and 2.8% for Helicobacter pylori. The rate of intestinal parasitosis was higher among Gp2 as compared to Gp1. The results also revealed higher prevalence of Cryptosporidium spp., Giardia lamblia, Entameba histolytica, and Cyclospora among Gp2 than Gp1. Swimming frequency, and duration influenced the infectious status that induced anemia, abnormal blood pressure, and heart rate. Infected swimmers with cryptosporidiosis had higher alanine transaminase levels, white blood cells, and differential cells but lower aspartate transaminase levels. Giardiasis showed higher reduction in the biochemical markers including ferritin, lactoferrin, iron, and transferrin among Gp 2, compared to Gp 1 and thus affected the swimmers' scores. Thus, raising swimmers' hygiene awareness and targeting health education is obliged.

Protective actions of nuclear factor erythroid 2-related factor 2 (NRF2) and downstream pathways against environmental stressors

Environmental risk factors, including noise, air pollution, chemical agents, ultraviolet radiation (UVR) and mental stress have a considerable impact on human health. Oxidative stress and inflammation are key players in molecular pathomechanisms of environmental pollution and risk factors. In this review, we delineate the impact of environmental risk factors and the protective actions of the nuclear factor erythroid 2-related factor 2 (NRF2) in connection to oxidative stress and inflammation. We focus on well-established studies that demonstrate the protective actions of NRF2 and its downstream pathways against different environmental stressors. State-of-the-art mechanistic considerations on NRF2 signaling are discussed in detail, e.g. classical concepts like KEAP1 oxidation/electrophilic modification, NRF2 ubiquitination and degradation. Specific focus is also laid on NRF2-dependent heme oxygenase-1 induction with detailed presentation of the protective down-stream pathways of heme oxygenase-1, including interaction with BACH1 system. The significant impact of all environmental stressors on the circadian rhythm and the interactions of NRF2 with the circadian clock will also be considered here. A broad range of NRF2 activators is discussed in relation to environmental stressor-induced health side effects, thereby suggesting promising new mitigation strategies (e.g. by nutraceuticals) to fight the negative effects of the environment on our health.

The activity of T- and B-cell links of specific protection of chicken-broilers under the influence of synbiotic preparation “Biomagn” and “Diolide” disinfectant

One of the most actual problems of modern poultry farming is to increase the preservation of chickens and ensure high intensity of their growth at all stages of rearing. The development of alternative methods of prevention and treatment of infectious diseases of poultry involves the use of preparations of natural or organic origin, which have antagonistic properties against infectious agents and are able to balance the immune response. A prominent place in the system of disease prevention and increasing the resistance of animals and poultry is the development of modern probiotic and bactericidal preparations. In view of this, we studied the influence of the synbiotic preparations “Biomagn” in combination with the disinfectant “Diolide” on the state of the T- and B-cell links of the specific immunity of broiler chickens during the period of their rearing. The preparation “Biomagn” is based on representatives of the normal commensal microflora - non-pathogenic lactic acid bacteria with antibacterial and immunomodulatory properties and additional components: magnesium chloride, chitosan, xylanase, protease, cellulase, milk thistle meal, acidity regulator, betaine and emulsifier. The specified remedy is used to ensure optimal level of metabolism, increase immune function, growth, safety of animals and poultry. The results of the research showed that the use of the synbiotic preparation “Biomagn” in combination with the disinfectant “Diolide” had a positive influence on the activity of T- and B-cell links of specific defense of broiler chickens organism during the period of their rearing. This is evidenced by an increase in the amount of T-lymphocytes (total, active and theophylline-resistant) and B-lymphocytes in the blood and an increase in their functional activity due to the redistribution of the receptor apparatus of immunocompetent cells. In particular, a decrease in the number of functionally inactive T- and B-lymphocytes in the blood and an increase in the number of cells with low and medium degree of avidity. Therefore, the use of a set of studied immunotropic preparations is a promising direction in increasing the resistance and productivity of poultry. This allows in industrial conditions of maintenance, without loss of productivity, to respond to technological factors that can lead to immunodeficiency, disease and death of poultry.

Neuroimmune axis of cardiovascular control: mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) make a substantial contribution to the global burden of disease. Prevention strategies have succeeded in reducing the effect of acute CVD events and deaths, but the long-term consequences of cardiovascular risk factors still represent the major cause of disability and chronic illness, suggesting that some pathophysiological mechanisms might not be adequately targeted by current therapies. Many of the underlying causes of CVD have now been recognized to have immune and inflammatory components. However, inflammation and immune activation were mostly regarded as a consequence of target-organ damage. Only more recent findings have indicated that immune dysregulation can be pathogenic for CVD, identifying a need for novel immunomodulatory therapeutic strategies. The nervous system, through an array of afferent and efferent arms of the autonomic nervous system, profoundly affects cardiovascular function. Interestingly, the autonomic nervous system also innervates immune organs, and neuroimmune interactions that are biologically relevant to CVD have been discovered, providing the foundation to target neural reflexes as an immunomodulatory therapeutic strategy. This Review summarizes how the neural regulation of immunity and inflammation participates in the onset and progression of CVD and explores promising opportunities for future therapeutic strategies.

Brain Areas Involved in Modulating the Immune Response Participating in Hypertension and Its Target Organ Damage

Significance: Hypertension is a multifactorial disease ensuing from the continuous challenge imposed by several risk factors on the cardiovascular system. Classically known pathophysiological alterations associated with hypertension comprise neurogenic mechanisms dysregulating the autonomic nervous system (ANS), vascular dysfunction, and excessive activation of the renin angiotensin system. During the past few years, a considerable number of studies indicated that immune activation and inflammation also have an important role in the onset and maintenance of hypertension. Critical Issues: On these premises, it has been necessary to reconsider the pathophysiological mechanisms underlying hypertension development, taking into account the potential interactions established between classically known determinants of high blood pressure and the immune system. Recent Advances: Interestingly, central nervous system areas controlling cardiovascular functions are enriched with Angiotensin II receptors. Observations showing that these brain areas are crucial for mediating peripheral ANS and immune responses were suggestive of a critical role of neuroimmune interactions in hypertension. In fact, the ANS, characterized by an intricate network of afferent and efferent fibers, represents an intermediate between the brain and peripheral responses that are essential for blood pressure regulation. Future Directions: In this review, we will summarize studies showing how specific brain areas can modulate immune responses that are involved in hypertension. Antioxid. Redox Signal. 35, 1515-1530.

Inflammation: A Mediator Between Hypertension and Neurodegenerative Diseases

Hypertension is the most prevalent and modifiable risk factor for stroke, vascular cognitive impairment, and Alzheimer's disease. However, the mechanistic link between hypertension and neurodegenerative diseases remains to be understood. Recent evidence indicates that inflammation is a common pathophysiological trait for both hypertension and neurodegenerative diseases. Low-grade chronic inflammation at the systemic and central nervous system levels is now recognized to contribute to the physiopathology of hypertension. This review speculates that inflammation represents a mediator between hypertension and neurodegenerative diseases, either by a decrease in cerebral blood flow or a disruption of the blood-brain barrier which will, in turn, let inflammatory cells and neurotoxic molecules enter the brain parenchyma. This may impact brain functions including cognition and contribute to neurodegenerative diseases. This review will thus discuss the relationship between hypertension, systemic inflammation, cerebrovascular functions, neuroinflammation, and brain dysfunctions. The potential clinical future of immunotherapies against hypertension and associated cerebrovascular risks will also be presented.

Genomics and Inflammation in Cardiovascular Disease

Chronic cardiovascular diseases are associated with inflammatory responses within the blood vessels and end organs. The origin of this inflammation has not been certain, and neither is its relationship to disease clear. There is a need to determine whether this association is causal or coincidental to the processes leading to cardiovascular disease. These processes are themselves complex: many cardiovascular diseases arise in conjunction with the presence of sustained elevation of blood pressure. Inflammatory processes have been linked to hypertension, and causality has been suggested. Evidence of causality poses the difficult challenge of linking the integrated and multifaceted biology of blood pressure regulation with vascular function and complex elements of immune system function. These include both, innate and adaptive immunity, as well as interactions between the host immune system and the omnipresent microorganisms that are encountered in the environment and that colonize and exist in commensal relationship with the host. Progress has been made in this task and has drawn on experimental approaches in animals, much of which have focused on hypertension occurring with prolonged infusion of angiotensin II. These laboratory studies are complemented by studies that seek to inform disease mechanism by examining the genomic basis of heritable disease susceptibility in human populations. In this realm too, evidence has emerged that implicates genetic variation affecting immunity in disease pathogenesis. In this article, we survey the genetic and genomic evidence linking high blood pressure and its end-organ injuries to immune system function and examine evidence that genomic factors can influence disease risk. © 2021 American Physiological Society. Compr Physiol 11:1-22, 2021.

CRIP1 expression in monocytes related to hypertension

Hypertension is a complex and multifactorial disorder caused by lifestyle and environmental factors, inflammation and disease-related genetic factors and is a risk factor for stroke, ischemic heart disease and renal failure. Although circulating monocytes and tissue macrophages contribute to the pathogenesis of hypertension, the underlying mechanisms are poorly understood. Cysteine rich protein 1 (CRIP1) is highly expressed in immune cells, and CRIP1 mRNA expression in monocytes associates with blood pressure (BP) and is up-regulated by proinflammatory modulation suggesting a link between CRIP1 and BP regulation through the immune system. To address this functional link, we studied CRIP1 expression in immune cells in relation to BP using a human cohort study and hypertensive mouse models. CRIP1 expression in splenic monocytes/macrophages and in circulating monocytes was significantly affected by angiotensin II (Ang II) in a BP-elevating dose (2 mg/kg/day). In the human cohort study, monocytic CRIP1 expression levels were associated with elevated BP, whereas upon differentiation of monocytes to macrophages this association along with the CRIP1 expression level was diminished. In conclusion, CRIP1-positive circulating and splenic monocytes seem to play an important role in hypertension related inflammatory processes through endogenous hormones such as Ang II. These findings suggest that CRIP1 may affect the interaction between the immune system, in particular monocytes, and the pathogenesis of hypertension.

Self-Reported Sensory Gating and Stress-Related Hypertension

BACKGROUND

Increasing evidence views hypertension as a stress-induced disorder. Stressors must be "gated" by the brain before any inflammatory or immune processes that contribute to hypertension are initiated. No studies were found that examined sensory gating in relation to hypertension.

OBJECTIVES

The aim of the study was to determine if disturbances in self-reported sensory gating could differentiate normotensive from hypertensive young adults.

METHODS

A nonmatched, case-control design was used. We administered an online survey to 163 young adult participants. Participants were predominantly female, in their mid-20s, well educated, and approximately evenly distributed by race and hypertension status. The Sensory Gating Inventory (SGI) measured gating disturbances.

RESULTS

The mean SGI scores were significantly higher among persons diagnosed with hypertension, reflecting a moderate effect size of sensory gating. After adjusting for confounders, however, the normotensive and hypertensive groups were not significantly different on their SGI scores.

DISCUSSION

With an observed moderate effect size of 0.35, but low power, more research is warranted regarding the role of gating disturbances in the development of stress-induced hypertension. Clinically, the SGI may be important for screening patients who would benefit from ambulatory blood pressure monitoring to identify persons with masked hypertension.

Loss of T cells influences sex differences in stress-related gene expression

Deficiencies in the adaptive immune system have been linked to anxiety-like behaviours and stress reactivity. Mice lacking T lymphocytes through knockout of the T cell receptor (TCR) β and δ chains were compared to wild type C57Bl/6 mice. Central stress circuitry gene expression was assessed following repeated restraint stress. TCRβ-/-δ-/- mice showed an increased baseline plasma corticosterone and exaggerated changes in stress-related gene expression after repeated restraint stress. Sexual dimorphic stress responses were observed in wild-type C57Bl/6 mice but not in TCRβ-/-δ-/- mice. These data suggest that T cell-brain interactions influence sex-differences in CNS stress circuitry and stress reactivity.

Environmental Noise-Induced Effects on Stress Hormones, Oxidative Stress, and Vascular Dysfunction: Key Factors in the Relationship between Cerebrocardiovascular and Psychological Disorders

The role of noise as an environmental pollutant and its adverse effects on health are being increasingly recognized. Beyond its direct effects on the auditory system (e.g., hearing loss and tinnitus induced by exposure to high levels of noise), chronic low-level noise exposure causes mental stress associated with known cardiovascular complications. According to recent estimates of the World Health Organization, exposure to traffic noise is responsible for a loss of more than 1.5 million healthy life years per year in Western Europe alone, a major part being related to annoyance, cognitive impairment, and sleep disturbance. Underlying mechanisms of noise-induced mental stress are centered on increased stress hormone levels, blood pressure, and heart rate, which in turn favor the development of cerebrocardiovascular disease such as stroke, arterial hypertension, ischemic heart disease, and myocardial infarction. Furthermore, traffic noise exposure is also associated with mental health symptoms and psychological disorders such as depression and anxiety, which further increase maladaptive coping mechanisms (e.g., alcohol and tobacco use). From a molecular point of view, experimental studies suggest that traffic noise exposure can increase stress hormone levels, thereby triggering inflammatory and oxidative stress pathways by activation of the nicotinamide adenine dinucleotide phosphate oxidase, uncoupling of endothelial/neuronal nitric oxide synthase inducing endothelial and neuronal dysfunction. This review elucidates the mechanisms underlying the relationship between noise exposure and cerebrocardiovascular and psychological disorders, focusing on mental stress signaling pathways including activation of the autonomous nervous system and endocrine signaling and its association with inflammation, oxidative stress, and vascular dysfunction.

Immunity and hypertension: New targets to lighten the pressure

LINKED ARTICLES

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Infiltrating T helper 17 cells in the paraventricular nucleus are pathogenic for stress-induced hypertension

Central neuroinflammation produced by both innate and adaptive immunities plays a major role in the development of stress-induced hypertension (SIH), but successful T cell immunoregulation for SIH requires that the T cells can access brain tissues. So far, both the effects of T helper 17 (Th17) cells on SIH and the pathway for T cells entry into the brain were unknown. Here we show that the blood pressure (BP), heart rate (HR) and the norepinephrine(NE) of the SIH rats were considerably higher, the numbers of Th17 cells and IL-17 were higher, relative to control. Anti-IL-17 attenuated the elevation of BP and HR of the SIH rats when microinjected into the paraventricular nucleus (PVN).Alb-FITC, after infusion into the carotid artery, were found in the brain parenchyma of the PVN in the SIH rats. We concluded that Th17 cells infiltrated the parenchyma of the paraventricular nucleus (PVN) via a compromised blood brain barrier (BBB) in response to stress and Th17 cells and IL-17 play an important role in the pathophysiology of SIH.

β‑estradiol alleviates hypertension‑ and concanavalin A‑mediated inflammatory responses via modulation of connexins in peripheral blood lymphocytes

Gap junctions (GJs) formed by connexins (Cxs) in T lymphocytes have been reported to have important roles in the T lymphocyte-driven inflammatory response and hypertension-mediated inflammation. Estrogen has a protective effect on cardiovascular diseases, including hypertension and it attenuates excessive inflammatory responses in certain autoimmune diseases. However, the mechanisms involved in regulating the pro-inflammatory response are complex and poorly understood. The current study investigated whether β-estradiol suppresses hypertension and pro-inflammatory stimuli-mediated inflammatory responses by regulating Cxs and Cx-mediated GJs in peripheral blood lymphocytes. Male, 16-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) rats were randomly divided into the following three groups: WKY rats, vehicle (saline)-treated SHRs, and β-estradiol (20 µg/kg/day)-treated SHRs. β-estradiol was administered subcutaneously for 5 weeks. Hematoxylin and eosin staining was performed to evaluate target organ injury. Flow cytometry and ELISA were used to measure the populations of T lymphocyte subtypes in the peripheral blood, and expression of Cx40/Cx43 in T cell subtypes, and pro-inflammation cytokines levels, respectively. ELISA, a dye transfer technique, immunofluorescence and immunoblotting were used to analyze the effect of β-estradiol on pro-inflammatory cytokine secretion, Cx-mediated GJs and the expression of Cxs in concanavalin A (Con A)-stimulated peripheral blood lymphocytes isolated from WKY rat. β-estradiol significantly decreased blood pressure and inhibited hypertension-induced target organ injury in SHRs. Additionally, β-estradiol treatment significantly improved the immune homeostasis of SHRs, as demonstrated by the decreased percentage of cluster of differentiation (CD)4⁺/CD8⁺ T-cell subset ratio, reduced serum levels of pro-inflammatory cytokines and increased the percentage of CD4⁺CD25⁺ T cells. β-estradiol also markedly reduced the expression of Cx40/Cx43 in T lymphocytes from SHRs. In vitro, β-estradiol significantly suppressed the production of pro-inflammatory cytokines, reduced communication via Cx-mediated gap junctions and decreased the expression of Cx40/Cx43 in Con A-stimulated lymphocytes. These results indicate that β-estradiol attenuates inflammation and end organ damage in hypertension, which may be partially mediated via downregulated expression of Cxs and reduced function of Cx-mediated GJ.

Hypertension linked to allostatic load: from psychosocial stress to inflammation and mitochondrial dysfunction

Although a large number of available treatments and strategies, the prevalence of cardiovascular diseases continues to grow worldwide. Emerging evidence supports the notion of counteracting stress as a critical component of a comprehensive therapeutic strategy for cardiovascular disease. Indeed, an unhealthy lifestyle is a burden to biological variables such as plasma glucose, lipid profile, and blood pressure control. Recent findings identify allostatic load as a new paradigm for an integrated understanding of the importance of psychosocial stress and its impact on the development and maintenance of cardiovascular disease. Allostasis complement homeostasis and integrates behavioral and physiological mechanisms by which genes, early experiences, environment, lifestyle, diet, sleep, and physical exercise can modulate and adapt biological responses at the cellular level. For example, variability is a physiological characteristic of blood pressure necessary for survival and the allostatic load in hypertension can contribute to its related cardiovascular morbidity and mortality. Therefore, the current review will focus on the mechanisms that link hypertension to allostatic load, which includes psychosocial stress, inflammation, and mitochondrial dysfunction. We will describe and discuss new insights on neuroendocrine-immune effects linked to allostatic load and its impact on the cellular and molecular responses; the links between allostatic load, inflammation, and endothelial dysfunction; the epidemiological evidence supporting the pathophysiological origins of hypertension; and the biological embedding of allostatic load and hypertension with an emphasis on mitochondrial dysfunction.

A Review of Wearable Solutions for Physiological and Emotional Monitoring for Use by People with Autism Spectrum Disorder and Their Caregivers

The goal of real-time feedback on physiological changes, stress monitoring and even emotion detection is becoming a technological reality. People in their daily life experience varying emotional states, some of which are negative and which can lead to decreased attention, decreased productivity and ultimately, reduced quality of life. Therefore, having a solution that continuously monitors the physiological signals of the person and assesses his or her emotional well-being could be a very valuable tool. This paper aims to review existing physiological and motional monitoring devices, highlight their features and compare their sensing capabilities. Such technology would be particularly useful for certain populations who experience rapidly changing emotional states such as people with autism spectrum disorder and people with intellectual disabilities. Wearable sensing devices present a potential solution that can support and complement existing behavioral interventions. This paper presents a review of existing and emerging products in the market. It reviews the literature on state-of-the-art prototypes and analyzes their usefulness, clinical validity, and discusses clinical perspectives. A small number of products offer reliable physiological internal state monitoring and may be suitable for people with Autism Spectrum Disorder (ASD). It is likely that more promising solutions will be available in the near future. Therefore, caregivers should be careful in their selection of devices that meet the care-receiver's personal needs and have strong research support for reliability and validity.

Increased expression and functionality of the gap junction in peripheral blood lymphocytes is associated with hypertension-mediated inflammation in spontaneously hypertensive rats

BACKGROUND

Imbalances in circulating T lymphocytes play critical roles in the pathogenesis of hypertension-mediated inflammation. Connexins (Cxs) in immune cells are involved in the maintenance of homeostasis of T lymphocytes. However, the association between Cxs in peripheral blood T lymphocytes and hypertension-mediated inflammation remains unknown. This study was designed to investigate the role of Cxs in T lymphocytes in hypertension-mediated inflammation in spontaneously hypertensive rats (SHRs).

METHODS

The systolic blood pressure (SBP) in Wistar-Kyoto (WKY) rats and SHRs was monitored using the tail-cuff method. The serum cytokine level was determined using ELISA. The proportions of different T-lymphocyte subtypes in the peripheral blood, the expressions of Cx40/Cx43 in the T-cell subtypes, and the gap junctional intracellular communication (GJIC) of peripheral blood lymphocytes were measured using flow cytometry (FC). The accumulations of Cx40/Cx43 at the plasma membrane and/or in the cytoplasm were determined using immunofluorescence staining. The in vitro mRNA levels of cytokines and GJIC in the peripheral blood lymphocytes were respectively examined using real-time PCR and FC after treatment with Gap27 and/or concanavalin A (Con A).

RESULTS

The percentage of CD4+ T cells and the CD4+/CD8+ ratio were high, and the accumulation or expressions of Cx40/Cx43 in the peripheral blood lymphocytes in SHRs were higher than in those of WKY rats. The percentage of CD8+ and CD4+CD25+ T cells was lower in SHRs. The serum levels of IL-2, IL-4 and IL-6 from SHRs were higher than those from WKY rats, and the serum levels of IL-2 and IL-6 positively correlated with the expression of Cx40/Cx43 in the peripheral blood T lymphocytes from SHRs. The peripheral blood lymphocytes of SHRs exhibited enhanced GJIC. Cx43-based channel inhibition, which was mediated by Gap27, remarkably reduced GJIC in lymphocytes, and suppressed IL-2 and IL-6 mRNA expressions in Con A stimulated peripheral blood lymphocytes.

CONCLUSIONS

Our data suggest that Cxs may be involved in the regulation of T-lymphocyte homeostasis and the production of cytokines. A clear association was found between alterations in Cxs expression or in Cx43-based GJIC and hypertension-mediated inflammation.

Age-related arterial immune cell infiltration in mice is attenuated by caloric restriction or voluntary exercise

Age-related arterial inflammation is associated with dysfunction of the arteries and increased risk for cardiovascular disease. To determine if aging increases arterial immune cell infiltration as well as the populations of immune cells principally involved, we tested the hypothesis that large elastic and resistance arteries in old mice would exhibit increased immune cell infiltration compared to young controls. Additionally, we hypothesized that vasoprotective lifestyle interventions such as lifelong caloric restriction or 8weeks of voluntary wheel running would attenuate age-related arterial immune cell infiltration. The aorta and mesenteric vasculature with surrounding perivascular adipose was excised from young normal chow (YNC, 4-6months, n=10), old normal chow (ONC, 28-29months, n=11), old caloric restricted (OCR, 28-29months, n=9), and old voluntary running (OVR, 28-29months, n=5) mice and digested to a single cell suspension. The cells were then labeled with antibodies against CD45 (total leukocytes), CD3 (pan T cells), CD4 (T helper cells), CD8 (cytotoxic T cells), CD19 (B cells), CD11b, and F4/80 (macrophages) and analyzed by flow cytometry. Total leukocytes, T cells (both CD4+ and CD8+ subsets), B cells, and macrophages in both aorta and mesentery were all 5- to 6-fold greater in ONC compared to YNC. Age-related increases in T cell (both CD4+ and CD8+), B cell, and macrophage infiltration in aorta were abolished in OCR mice. OVR mice exhibited 50% lower aortic T cell and normalized macrophage infiltration. B cell infiltration was not affected by VR. Age-related mesenteric CD8+ T cell and macrophage infiltration was normalized in OCR and OVR mice compared to young mice, whereas B cell infiltration was normalized by CR but not VR. Splenic CD4+ T cells from ONC mice exhibited a 3-fold increase in gene expression for the T helper (Th) 1 transcription factor, Tbet, and a 4-fold increase in FoxP3, a T regulatory cell transcription factor, compared to YNC. Splenic B cells and mesenteric macrophages from old mice exhibited decreased proinflammatory cytokine gene expression regardless of treatment group. These results demonstrate that aging is associated with infiltration of immune cells around both the large-elastic and resistance arteries and that the vasoprotective lifestyle interventions, CR and VR, can ameliorate age-related arterial immune cell infiltration.

CD8+ T cells promote cytokine responses to stress

Psychological stress is known to have profound effects on immune function and to promote inflammatory conditions. Elevated circulating levels of cytokines associated with stress are known to increase the risk to several diseases, but little is known about this mechanism. This study assessed the role of T cells on cytokine levels after exposure to stress in the learned helplessness paradigm. Adoptive transfer of CD4⁺ T cells into Rag2^-/- mice did not change cytokine levels to stress while CD8⁺ T cells resulted in an increase in TNF-α, IL-6 and IFN-γ in stressed Rag2^-/- mice. Moreover, depletion of CD8⁺ T cells in WT mice abolished these cytokine responses to stress. Corticosterone and behavioral stress responsiveness was impaired in Rag2^-/- mice reconstituted with CD8⁺ T cells. Notably, depletion of these cells in WT mice had no effect on behavior or corticosterone levels. Exposure to stress did not change the expression of canonical markers of T cell activation including CD62L and CD44 or modified intracellular cytokine content, suggesting that they are not the main producers of circulating cytokines in response to stress. These results show that CD8⁺ T cells promote TNF-α, IL-6 and IFN-γ responses to stress, possibly by stimulating non-lymphoid cells.

Mechanisms in hypertension and target organ damage: Is the role of the thymus key? (Review)

A variety of cells and cytokines have been shown to be involved in the whole process of hypertension. Data from experimental and clinical studies on hypertension have confirmed the key roles of immune cells and inflammation in the process. Dysfunction of the thymus, which modulates the development and maturation of lymphocytes, has been shown to be associated with the severity of hypertension. Furthermore, gradual atrophy, functional decline or loss of the thymus has been revealed to be associated with aging. The restoration or enhancement of thymus function via upregulation in the expression of thymus transcription factors forkhead box N1 or thymus transplantation may provide an option to halt or reverse the pathological process of hypertension. Therefore, the thymus may be key in hypertension and associated target organ damage, and may provide a novel treatment strategy for the clinical management of patients with hypertension in addition to different commercial drugs. The purpose of this review is to summarize and discuss the advances in our understanding of the impact of thymus function on hypertension from data from animal and human studies, and the potential mechanisms.

Effects of noise on vascular function, oxidative stress, and inflammation: mechanistic insight from studies in mice

Aims

Epidemiological studies indicate that traffic noise increases the incidence of coronary artery disease, hypertension and stroke. The underlying mechanisms remain largely unknown. Field studies with nighttime noise exposure demonstrate that aircraft noise leads to vascular dysfunction, which is markedly improved by vitamin C, suggesting a key role of oxidative stress in causing this phenomenon.

Methods and results

We developed a novel animal model to study the vascular consequences of aircraft noise exposure. Peak sound levels of 85 and mean sound level of 72 dBA applied by loudspeakers for 4 days caused an increase in systolic blood pressure, plasma noradrenaline and angiotensin II levels and induced endothelial dysfunction. Noise increased eNOS expression but reduced vascular NO levels because of eNOS uncoupling. Noise increased circulating levels of nitrotyrosine, interleukine-6 and vascular expression of the NADPH oxidase subunit Nox2, nitrotyrosine-positive proteins and of endothelin-1. FACS analysis demonstrated an increase in infiltrated natural killer-cells and neutrophils into the vasculature. Equal mean sound pressure levels of white noise for 4 days did not induce these changes. Comparative Illumina sequencing of transcriptomes of aortic tissues from aircraft noise-treated animals displayed significant changes of genes in part responsible for the regulation of vascular function, vascular remodelling, and cell death.

Conclusion

We established a novel and unique aircraft noise stress model with increased blood pressure and vascular dysfunction associated with oxidative stress. This animal model enables future studies of molecular mechanisms, mitigation strategies, and pharmacological interventions to protect from noise-induced vascular damage.

Current Perspectives on Antihypertensive Probiotics

Hypertension is a major risk factor for cardiovascular diseases. Optimizing blood pressure results in an overall health outcome. Over the years, the gut microbiota has been found to play a significant role in host metabolic processes, immunity, and physiology. Dietary strategies have therefore become a target for restoring disturbed gut microbiota to treat metabolic diseases. Probiotics and their fermented products have been shown in many studies to lower blood pressure by suppressing nitrogen oxide production in microphages, reducing reactive oxygen species, and enhancing dietary calcium absorption. Other studies have shown that hypertension could be caused by many factors including hypercholesterolemia, chronic inflammation, and inconsistent modulation of the renin-angiotensin system. This review discusses the antihypertensive roles of probiotics and their fermented products via the reduction of serum cholesterol levels, anti-inflammation, and inhibition of angiotensin-converting enzyme. The ability of recombinant probiotics to reduce high blood pressure has also been discussed.

Hydrogen Sulfide Attenuates Hypertensive Inflammation via Regulating Connexin Expression in Spontaneously Hypertensive Rats

BACKGROUND Hydrogen sulfide (H2S) has anti-inflammatory and anti-hypertensive effects, and connexins (Cxs) are involved in regulation of immune homeostasis. In this study, we explored whether exogenous H2S prevents hypertensive inflammation by regulating Cxs expression of T lymphocytes in spontaneously hypertensive rats (SHR). MATERIAL AND METHODS We treated SHR with sodium hydrosulfide (NaHS) for 9 weeks. Vehicle-treated Wistar-Kyoto rats (WKYs) were used as a control. The arterial pressure was monitored by the tail-cuff method, and vascular function in basilar arteries was examined by pressure myography. Hematoxylin and eosin staining was used to show vascular remodeling and renal injury. The percentage of T cell subtypes in peripheral blood, surface expressions of Cx40/Cx43 on T cell subtypes, and serum cytokines level were determined by flow cytometry or ELISA. Expression of Cx40/Cx43 proteins in peripheral blood lymphocytes was analyzed by Western blot. RESULTS Chronic NaHS treatment significantly attenuated blood pressure elevation, and inhibited inflammation of target organs, vascular remodeling, and renal injury in SHR. Exogenous NaHS also improved vascular function by attenuating KCl-stimulated vasoconstrictor response in basilar arteries of SHR. In addition, chronic NaHS administration significantly suppressed inflammation of peripheral blood in SHR, as evidenced by the decreased serum levels of IL-2, IL-6, and CD4/CD8 ratio and the increased IL-10 level and percentage of regulatory T cells. NaHS treatment decreased hypertension-induced Cx40/Cx43 expressions in T lymphocytes from SHR. CONCLUSIONS Our data demonstrate that H2S reduces hypertensive inflammation, at least partly due to regulation of T cell subsets balance by Cx40/Cx43 expressions inhibition.

Angiotensin II-induced Hypertension is Reduced by Deficiency of P-selectin Glycoprotein Ligand-1

Identification of inflammatory mediators that regulate the vascular response to vasopressor molecules may aid in the development of novel therapeutic agents to treat or prevent hypertensive vascular diseases. Leukocytes have recently been shown to be capable of modifying blood pressure responses to vasopressor molecules. The purpose of this study was to test the hypothesis that deficiency of the leukocyte ligand, Psgl-1, would reduce the pressor response to angiotensin II (Ang II). Mice deficient in Psgl-1 (Psgl-1^−/−) along with wild-type (WT) controls were treated for 2 weeks with a continuous infusion of Ang II. No differences in blood pressure between the groups were noted at baseline, however after 5 days of Ang II infusion, systolic blood pressures were higher in WT compared to Psgl-1^−/− mice. The pressor response to acute administration of high dose Ang II was also attenuated in Psgl-1^−/− compared to WT mice. Chimeric mice with hematopoietic deficiency of Psgl-1 similarly showed a reduced pressor response to Ang II. This effect was associated with reduced plasma interleukin-17 (IL-17) levels in Psgl-1^−/− mice and the reduced pressor response was restored by administration of recombinant IL-17. In conclusion, hematopoietic deficiency of Psgl-1 attenuates Ang II-induced hypertension, an effect that may be mediated by reduced IL-17.

Blood Pressure and Fibrinogen Responses to Mental Stress as Predictors of Incident Hypertension over an 8-Year Period

Background

Heightened blood pressure (BP) responses to mental stress predict raised BP levels over subsequent years, but evidence for associations with incident hypertension is limited, and the significance of inflammatory responses is uncertain.

Purpose

We investigated the relationship between BP and plasma fibrinogen responses to stress and incident hypertension over an average 8-year follow-up.

Method

Participants were 636 men and women (mean age 59.1 years) from the Whitehall II epidemiological cohort with no history of cardiovascular disease and hypertension. They performed standardized behavioral tasks (color/word conflict and mirror tracing), and hypertension was defined by clinic measures and medication status.

Results

Of participants in the highest systolic BP reactivity tertile, 29.3 % became hypertensive over the follow-up period compared with 16.5 % of those in the lowest tertile, with an odds ratio of 2.02 (95 % CI 1.17–3.88, p = 0.012) after adjustment for age, sex, grade of employment, body mass index, smoking, alcohol consumption, physical activity, follow-up time, subjective stress response, perceived task difficulty, perceived task engagement, and baseline BP. Similar associations were observed for diastolic BP reactivity (odds ratio 2.05, 95 % CI 1.23–3.40, p = 0.006) and for impaired systolic BP post-stress recovery (odds ratio 2.06, 95 % CI 1.19–3.57, p = 0.010). Fibrinogen reactions to tasks also predicted future hypertension in women (odds ratio 2.64, 95 % CI 1.11–6.30, p = 0.029) but not men.

Conclusions

These data suggest that heightened cardiovascular and inflammatory reactivity to mental stress is associated with hypertension risk, and may be a mechanism through which psychosocial factors impact on the development of hypertension.

Contributions of the adaptive immune system to mood regulation: Mechanisms and pathways of neuroimmune interactions

Clinical and basic studies of functional interactions between adaptive immunity, affective states, and brain function are reviewed, and the neural, humoral, and cellular routes of bidirectional communication between the brain and the adaptive immune system are evaluated. In clinical studies of depressed populations, lymphocytes-the principal cells of the adaptive immune system-exhibit altered T cell subtype ratios and CD4+ helper T cell polarization profiles. In basic studies using psychological stress to model depression, T cell profiles are altered as well, consistent with stress effects conveyed by the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. Lymphocytes in turn have effects on behavior and CNS structure and function. CD4+ T cells in particular appear to modify affective behavior and rates of hippocampal dentate gyrus neurogenesis. These observations force the question of how such actions are carried out. CNS effects may occur via cellular and molecular mechanisms whereby effector memory T cells and the cytokine profiles they produce in the blood interact with the blood-brain barrier in ways that remain to be clarified. Understanding the mechanisms by which T cells polarize and interact with the brain to alter mood states is key to advances in the field, and may permit development of therapies that target cells in the periphery, thus bypassing problems associated with bioavailability of drugs within the brain.

Type 2 diabetes mellitus and psychological stress - a modifiable risk factor

Psychological stress is common in many physical illnesses and is increasingly recognized as a risk factor for disease onset and progression. An emerging body of literature suggests that stress has a role in the aetiology of type 2 diabetes mellitus (T2DM) both as a predictor of new onset T2DM and as a prognostic factor in people with existing T2DM. Here, we review the evidence linking T2DM and psychological stress. We highlight the physiological responses to stress that are probably related to T2DM, drawing on evidence from animal work, large epidemiological studies and human laboratory trials. We discuss population and clinical studies linking psychological and social stress factors with T2DM, and give an overview of intervention studies that have attempted to modify psychological or social factors to improve outcomes in people with T2DM.

Redox regulation of cardiovascular inflammation - Immunomodulatory function of mitochondrial and Nox-derived reactive oxygen and nitrogen species

Oxidative stress is a major hallmark of cardiovascular diseases although a causal link was so far not proven by large clinical trials. However, there is a close association between oxidative stress and inflammation and increasing evidence for a causal role of (low-grade) inflammation for the onset and progression of cardiovascular diseases, which may serve as the missing link between oxidative stress and cardiovascular morbidity and mortality. With the present review we would like to highlight the multiple redox regulated pathways in inflammation, discuss the sources of reactive oxygen and nitrogen species that are of interest for these processes and finally discuss the importance of angiotensin II (AT-II) as a trigger of cardiovascular inflammation and the initiation and progression of cardiovascular diseases.

Targeting vascular (endothelial) dysfunction

Cardiovascular diseases are major contributors to global deaths and disability-adjusted life years, with hypertension a significant risk factor for all causes of death. The endothelium that lines the inner wall of the vasculature regulates essential haemostatic functions, such as vascular tone, circulation of blood cells, inflammation and platelet activity. Endothelial dysfunction is an early predictor of atherosclerosis and future cardiovascular events. We review the prognostic value of obtaining measurements of endothelial function, the clinical techniques for its determination, the mechanisms leading to endothelial dysfunction and the therapeutic treatment of endothelial dysfunction. Since vascular oxidative stress and inflammation are major determinants of endothelial function, we have also addressed current antioxidant and anti-inflammatory therapies. In the light of recent data that dispute the prognostic value of endothelial function in healthy human cohorts, we also discuss alternative diagnostic parameters such as vascular stiffness index and intima/media thickness ratio. We also suggest that assessing vascular function, including that of smooth muscle and even perivascular adipose tissue, may be an appropriate parameter for clinical investigations.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

T-cell subsets are associated with serum homocysteine concentration in patients with essential hypertension

OBJECTIVE

To explore the association between serum homocysteine (Hcy) concentration and T-cell subsets from patients with essential hypertension.

PATIENTS AND METHODS

A total of 218 essential hypertension patients were recruited, of which 170 were H-type essential hypertensive and 48 were non-H-type essential hypertensive. H-type essential hypertensive patients were divided into three groups by concentration of serum Hcy. The peripheral blood T-cell subsets (CD3⁺%, CD4⁺%, CD8⁺ T%, CD4⁺/CD8⁺) and clinical features including age, sex, serum creatinine, uric acid, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were recorded and analyzed with T-cell subsets which were counted by fluorescence activated cytometry.

RESULTS

Compared with non-H-type hypertensive patients, CD4⁺ T-cell percentage in peripheral blood was significantly decreased in H-type hypertensive patients. Because of the increase of Hcy level, CD4⁺ T-cell percentage decreased. Linear regression analysis showed that Hcy level was negatively correlated with CD4⁺ T-cell percentage; however, it was positively correlated with CD3⁺ T-cell percentage.

CONCLUSION

A direct association between serum Hcy concentrations and T-cell percentage was observed in patients with essential hypertension. This observation indicates that T-cell subsets might play an important role in hypertension.

Novel Immune Mechanisms in Hypertension and Cardiovascular Risk

PURPOSE OF REVIEW

Hypertension is a common disorder with substantial impact on public health due to highly elevated cardiovascular risk. The mechanisms still remain unclear and treatments are not sufficient to reduce risk in majority of patients. Inflammatory mechanisms may provide an important mechanism linking hypertension and cardiovascular risk. We aim to review newly identified immune and inflammatory mechanisms of hypertension with focus on their potential therapeutic impact.

RECENT FINDINGS

In addition to the established role of the vasculature, kidneys and central nervous system in pathogenesis of hypertension, low-grade inflammation contributes to this disorder as indicated by experimental models and GWAS studies pointing to SH2B3 immune gene as top key driver of hypertension. Immune responses in hypertension are greatly driven by neoantigens generated by oxidative stress and modulated by chemokines such as RANTES, IP-10 and microRNAs including miR-21 and miR-155 with other molecules under investigation. Cells of both innate and adoptive immune system infiltrate vasculature and kidneys, affecting their function by releasing pro-inflammatory mediators and reactive oxygen species.

SUMMARY

Immune and inflammatory mechanisms of hypertension provide a link between high blood pressure and increased cardiovascular risk, and reduction of blood pressure without attention to these underlying mechanisms is not sufficient to reduce risk.

Hypertension, cerebrovascular impairment, and cognitive decline in aged AβPP/PS1 mice

Cardiovascular risk factors, especially hypertension, are also major risk factors for Alzheimer's disease (AD). To elucidate the underlying vascular origin of neurodegenerative processes in AD, we investigated the relation between systolic blood pressure (SBP) cerebral blood flow (CBF) and vasoreactivity with brain structure and function in a 16-18 months old double transgenic AβPP_swe/PS1_dE9 (AβPP/PS1) mouse model for AD. These aging AβPP/PS1 mice showed an increased SBP linked to a declined regional CBF. Furthermore, using advanced MRI techniques, decline of functional and structural connectivity was revealed in the AD-like mice coupled to impaired cognition, increased locomotor activity, and anxiety-related behavior. Post mortem analyses demonstrated also increased neuroinflammation, and both decreased synaptogenesis and neurogenesis in the AβPP/PS1 mice. Additionally, deviant levels of fatty acids and sterols were present in the brain tissue of the AβPP/PS1 mice indicating maladapted brain fatty acid metabolism. Our findings suggest a link between increased SBP, decreased cerebral hemodynamics and connectivity in an AD mouse model during aging, leading to behavioral and cognitive impairments. As these results mirror the complex clinical symptomatology in the prodromal phase of AD, we suggest that this AD-like murine model could be used to investigate prevention and treatment strategies for early AD patients. Moreover, this study helps to develop more efficient therapies and diagnostics for this very early stage of AD.

Deletion of p22phox-dependent oxidative stress in the hypothalamus protects against obesity by modulating 3-adrenergic mechanisms

A role for oxidative stress in the brain has been suggested in the pathogenesis of diet-induced obesity (DIO), although the underlying neural regions and mechanisms remain incompletely defined. We tested the hypothesis that NADPH oxidase-dependent oxidative stress in the paraventricular nucleus (PVN), a hypothalamic energy homeostasis center, contributes to the development of DIO. Cre/LoxP technology was coupled with selective PVN adenoviral microinjection to ablate p22^phox , the obligatory subunit for NADPH oxidase activity, in mice harboring a conditional p22^phox allele. Selective deletion of p22^phox in the PVN protected mice from high-fat DIO independent of changes in food intake or locomotor activity. This was accompanied by β₃-adrenoceptor-dependent increases in energy expenditure, elevations in brown adipose tissue thermogenesis, and browning of white adipose tissue. These data reveal a potentially novel role for brain oxidative stress in the development of DIO by modulating β₃-adrenoceptor mechanisms and point to the PVN as an underlying neural site.

Inflammation in Fear- and Anxiety-Based Disorders: PTSD, GAD, and Beyond

The study of inflammation in fear- and anxiety-based disorders has gained interest as growing literature indicates that pro-inflammatory markers can directly modulate affective behavior. Indeed, heightened concentrations of inflammatory signals, including cytokines and C-reactive protein, have been described in posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), and phobias (agoraphobia, social phobia, etc.). However, not all reports indicate a positive association between inflammation and fear- and anxiety-based symptoms, suggesting that other factors are important in future assessments of inflammation's role in the maintenance of these disorders (ie, sex, co-morbid conditions, types of trauma exposure, and behavioral sources of inflammation). The most parsimonious explanation of increased inflammation in PTSD, GAD, PD, and phobias is via the activation of the stress response and central and peripheral immune cells to release cytokines. Dysregulation of the stress axis in the face of increased sympathetic tone and decreased parasympathetic activity characteristic of anxiety disorders could further augment inflammation and contribute to increased symptoms by having direct effects on brain regions critical for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Taken together, the available data suggest that targeting inflammation may serve as a potential therapeutic target for treating these fear- and anxiety-based disorders in the future. However, the field must continue to characterize the specific role pro-inflammatory signaling in the maintenance of these unique psychiatric conditions.

Therapeutic effects of stress-programmed lymphocytes transferred to chronically stressed mice

Our group has recently provided novel insights into a poorly understood component of intercommunication between the brain and the immune system by showing that psychological stress can modify lymphocytes in a manner that may boost resilience to psychological stress. To demonstrate the influence of the adaptive immune system on mood states, we previously showed that cells from lymph nodes of socially defeated mice, but not from unstressed mice, conferred anxiolytic and antidepressant-like effects and elevated hippocampal cell proliferation when transferred into naïve lymphopenic Rag2(-/-) mice. In the present study, we asked whether similar transfer could be anxiolytic and antidepressant when done in animals that had been rendered anxious and depressed by chronic psychological stress. First, we demonstrated that lymphopenic Rag2(-/-) mice and their wild-type C57BL/6 mouse counterparts had similar levels of affect normally. Second, we found that following chronic (14days) restraint stress, both groups displayed an anxious and depressive-like phenotype and decreased hippocampal cell proliferation. Third, we showed that behavior in the open field test and light/dark box was normalized in the restraint-stressed Rag2(-/-) mice following adoptive transfer of lymph node cells from green fluorescent protein (GFP) expressing donor mice previously exposed to chronic (14days) of social defeat stress. Cells transferred from unstressed donor mice had no effect on behavior. Immunolabeling of GFP+ cells confirmed that tissue engraftment had occurred at 14days after transfer. We found GFP+ lymphocytes in the spleen, lymph nodes, blood, choroid plexus, and meninges of the recipient Rag2(-/-) mice. The findings suggest that the adaptive immune system may play a key role in promoting recovery from chronic stress. The data support using lymphocytes as a novel therapeutic target for anxiety states.

Immune function in Amazonian horticulturalists

BACKGROUND

Amazonian populations are exposed to diverse parasites and pathogens, including protozoal, bacterial, fungal and helminthic infections. Yet much knowledge of the immune system is based on industrialised populations where these infections are relatively rare.

AIM

This study examines distributions and age-related differences in 22 measures of immune function for Bolivian forager-horticulturalists and US and European populations.

SUBJECTS AND METHODS

Subjects were 6338 Tsimane aged 0-90 years. Blood samples collected between 2004-2014 were analysed for 5-part blood differentials, C-reactive protein, erythrocyte sedimentation rate (ESR) and total immunoglobulins E, G, A and M. Flow cytometry was used to quantify naïve and non-naïve CD4 and CD8 T cells, natural killer cells, and B cells.

RESULTS

Compared to reference populations, Tsimane have elevated levels of most immunological parameters, particularly immunoglobulins, eosinophils, ESR, B cells, and natural killer cells. However, monocytes and basophils are reduced and naïve CD4 cells depleted in older age groups.

CONCLUSION

Tsimane ecology leads to lymphocyte repertoires and immunoglobulin profiles that differ from those observed in industrialised populations. These differences have consequences for disease susceptibility and co-vary with patterns of other life history traits, such as growth and reproduction.

Activation of Human T Cells in Hypertension: Studies of Humanized Mice and Hypertensive Humans

Emerging evidence supports an important role for T cells in the genesis of hypertension. Because this work has predominantly been performed in experimental animals, we sought to determine whether human T cells are activated in hypertension. We used a humanized mouse model in which the murine immune system is replaced by the human immune system. Angiotensin II increased systolic pressure to 162 versus 116 mm Hg for sham-treated animals. Flow cytometry of thoracic lymph nodes, thoracic aorta, and kidney revealed increased infiltration of human leukocytes (CD45(+)) and T lymphocytes (CD3(+) and CD4(+)) in response to angiotensin II infusion. Interestingly, there was also an increase in the memory T cells (CD3(+)/CD45RO(+)) in the aortas and lymph nodes. Prevention of hypertension using hydralazine and hydrochlorothiazide prevented the accumulation of T cells in these tissues. Studies of isolated human T cells and monocytes indicated that angiotensin II had no direct effect on cytokine production by T cells or the ability of dendritic cells to drive T-cell proliferation. We also observed an increase in circulating interleukin-17A producing CD4(+) T cells and both CD4(+) and CD8(+) T cells that produce interferon-γ in hypertensive compared with normotensive humans. Thus, human T cells become activated and invade critical end-organ tissues in response to hypertension in a humanized mouse model. This response likely reflects the hypertensive milieu encountered in vivo and is not a direct effect of the hormone angiotensin II.

Assessment of Oxidative DNA Damage by Alkaline Comet Assay in Human Essential Hypertension

The objective of the present study was to investigate the antioxidant status and the extent of oxidative DNA damage in lymphocytes and their relation with essential hypertension (EHT). A total of 100 South Indian subjects aged 30-65 were included for the study. Of these 50 were normotensive controls (group-1) with blood pressure ≥120/80 mm Hg, 50 were newly diagnosed (group-2) and were not on any antihypertensive drugs, but had systolic blood pressure ranging between 140 and 160 mmHg and diastolic blood pressure 95-100 mmHg and 50 newly diagnosed essential hypertensive patients underwent drug therapy for 1 year was considered as group-3. Enzymatic and non-enzymatic antioxidants significantly decreased and lymphocyte DNA damage was significantly increased in newly diagnosed hypertensive patients compared with control group. The major decrease in DNA damage and significant improvement in enzymatic and non-enzymatic antioxidants were observed after 1 year of antihypertensive therapy in treated group compared with newly diagnosed hypertensive patients. Total antioxidant status and lymphocyte DNA damage showed a strong negative correlation in all the three groups. Essential hypertension associated with oxidative stress which in turn causes genotoxic susceptibility to variety of disease including cancer. In the absence of DNA repair process and DNA checkpoint mechanisms, the genomic integrity is susceptible to extensive damage. In our study, increased oxidative DNA damage and decreased antioxidant levels were frequently observed in the newly diagnosed essential hypertensive patients, suggesting that oxidative stress is important in the pathogenesis of EHT. Therefore, the present study has additional clinical implication. Further investigations with large number of patients along with antioxidant supplement are highly warranted.

Dysregulation of T cell subsets in the pathogenesis of hypertension

Essential hypertension (EH) and its complications have had a severe impact on public health. However, the underlying mechanisms of the pathogenesis of EH remain largely unknown. Recent investigations, predominantly in rats and mice, have provided evidence that dysregulation of distinct functions of T lymphocyte subsets is a potentially important mechanism in the pathogenesis of hypertension. We critically reviewed recent findings and propose an alternative explanation on the understanding of dysfunctional T lymphocyte subsets in the pathogenesis of hypertension. The hypothesis is that hypertensive stimuli, directly and indirectly, increase local IL-6 levels in the cardiovascular system and kidney, which may promote peripheral imbalance in the differentiation and ratio of Th17 and T regulatory cells. This results in increased IL-17 and decreased IL-10 in perivascular adipose tissue and adventitia contributing to the development of hypertension in experimental animal models. Further investigation in the field is warranted to inform new translational advances that will promote to understand the pathogenesis of EH and develop novel approaches to prevent and treat EH.

Sympathoexcitation and arterial hypertension associated with obstructive sleep apnea and cyclic intermittent hypoxia

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway obstruction during sleep. These obstructive episodes are characterized by cyclic intermittent hypoxia (CIH), by sleep fragmentation, and by hemodynamic instability, and they result in sustained sympathoexcitation and elevated arterial pressure that persist during waking, after restoration of normoxia. Early studies established that 1) CIH, rather than sleep disruption, accounts for the increase in arterial pressure; 2) the increase in arterial pressure is a consequence of the sympathoactivation; and 3) arterial hypertension after CIH exposure requires an intact peripheral chemoreflex. More recently, however, evidence has accumulated that sympathoactivation and hypertension after CIH are also dependent on altered central sympathoregulation. Furthermore, although many molecular pathways are activated in both the carotid chemoreceptor and in the central nervous system by CIH exposure, two specific neuromodulators-endothelin-1 and angiotensin II-appear to play crucial roles in mediating the sympathetic and hemodynamic response to intermittent hypoxia.

Autonomic dysfunction determines stress-induced cardiovascular and immune complications in mice

BACKGROUND

Clinical studies suggest that acute inflammation in patients with elevated heart rate (HR) increases morbidity and mortality. The SJL/J (SJL) inbred mouse strain is a unique genetic model that has higher HR and systemic and vascular inflammation compared with C3HeB/FeJ (C3HeB) mice. The goal of this study was to investigate the role of stress on cardiac and vascular complications between 2 strains.

METHODS AND RESULTS

Radiotelemetry was used for continuous recordings of HR and blood pressure in mice. Hemodynamic differences between mouse strains were very small without stress; however, tail-cuff training generated mild stress and significantly increased HR (≈2-fold) in SJL compared with C3HeB mice. Circulating proinflammatory monocytes (CD11b(+)Ly6C(H) (i)) significantly increased in SJL mice but not in C3HeB mice after stress. Presence of Ly6C(+) cells in injured carotids was elevated only in SJL mice after stress; however, a transfer of bone marrow cells from SJL/C3HeB to C3HeB/SJL chimeras had no effect on HR or vascular inflammation following stress. Arterial inflammation (VCAM-1(+)) was greater in SJL inbred mice or SJL recipient chimeras, even without stress or injury. HR variability was reduced in SJL mice compared with C3HeB mice.

CONCLUSIONS

We found that impaired parasympathetic activity is central for stress-induced elevation of HR and systemic and vascular inflammation; however, immune cells from stress-susceptible mice had no effect on HR or vascular inflammation in stress-protected mice.

Valsartan Attenuates Atherosclerosis via Upregulating the Th2 Immune Response in Prolonged Angiotensin II-Treated ApoE(-/-) Mice

Valsartan has a protective effect against hypertension and atherosclerosis in humans and experimental animal models. This study aimed to determine the effect of prolonged treatment with angiotensin II (Ang II) on atherosclerosis and the effect of valsartan on the activity of CD4(+) T lymphocyte subsets. The results showed that prolonged treatment (8 wks) with exogenous Ang II resulted in an increased atherosclerotic plaque size and a switch of stable-to-unstable plaque via modulating on CD4(+) T lymphocyte activity, including an increase in the T helper cell type 1 (Th1) and Th17 cells and a decrease in Th2 and regulatory T (Treg) cells. In contrast, valsartan treatment efficiently reversed the imbalance in CD4(+) T lymphocyte activity, ameliorated atherosclerosis and elicited a stable plaque phenotype in addition to controlling blood pressure. In addition, treatment with anti-interleukin (IL)-5 monoclonal antibodies weakened the antiatherosclerotic effects of valsartan without affecting blood pressure.