Neuroinflammation and sympathetic overactivity: Mechanisms and implications in hypertension

A temperature-ultrasound sensitive nanoparticle delivery system for exploring central neuroinflammation mechanism in stroke-heart syndrome

BACKGROUND

Cardiovascular events secondary to stroke-collectively classified as stroke-heart syndrome-greatly impair the patient's prognosis, however its underlying mechanism has yet to be determined. To investigate the mechanism of central neuroinflammation and its effects on stroke-heart syndrome, a temperature-ultrasound responsive brain-targeted drug delivery system, DATS/MION-LPE, was synthesized to specifically study neuroinflammation in the mouse middle cerebral artery occlusion (MCAO) model.

RESULTS

The specific polymer of DATS/MION-LPE can close the nanoparticle pores at 37 °C, restricting drug release in the circulation. After the nanoparticles were targeted to brains, the polymer can be cleaved under external ultrasound irradiation, reopening the nanoparticle pores and allowing drug release, therefore directly managing the neuroinflammation. After a stroke, a significant cerebral inflammation occurred, with elevated IL-1β and pyrin domain-containing 3 (NLRP3) inflammasome. Accordingly, significantly increased histone deacetylase 6 (HDAC6) and decreased sirtuin 1 (SIRT1) were observed. An antagonistic relationship between HDAC6 and SIRT1 was found, which can jointly regulate the cerebral NLRP3 expression. The systemic IL-1β and ATP levels were increased after the stroke, accompanied by a significant heart injury including contractile dysfunction, elevated IL-1β levels, and oxidative stress. Meanwhile, neuroinflammation can trigger sympathetic nervous overexcitation with associated heart damage. DATS/MION-LPE can targetedly effect on ischemic brain, exhibiting cerebral and cardiac protective effects including downregulated cerebral NLRP3 and HDAC6 expressions, upregulated SIRT1 expressions in brain, reduced IL-1β and ATP in circulation, and alleviated cardiac impairment.

CONCLUSION

This study introduced the key role of neuroinflammation in stroke-heart syndrome and first investigated the crucial HDAC6/SIRT1-NLRP3 circuit in this process. Heart injury secondary to stroke is mediated by neuroinflammation induced systemic inflammatory responses and sympathoexcitation. DATS/MION-LPE is a unique tool and effective therapeutic agent, which provides new insights into combinational heart and cardiac protection.

Placental ischemia-upregulated angiotensin II type 1 receptor in hypothalamic paraventricular nucleus contributes to hypertension in rat

Preeclampsia (PE) is associated with increased angiotensin II sensitivity and poor neurological outcomes marked by temporal loss of neural control of blood pressure. Yet the role of centrally expressed angiotensin II type 1 receptor (AT1R) within the paraventricular nucleus of the hypothalamus (PVN) in the PE model is not understood. In a PE rat model with reduced placental perfusion pressure (RUPP) induced on gestational day 14 (GD14), the PVN expression and cellular localization of AT1R were assessed using immunofluorescence and western blotting. The sensitivity of RUPP to acute angiotensin II infusion was assessed. AT1R was antagonized by losartan (100 µg/kg/day) for 5 days intracerebroventricularly (ICV). Hemodynamic data and samples were collected on GD19 for further analysis. RUPP upregulated (p < 0.05) mRNA and protein of AT1R within the PVN and lowered (p < 0.05) circulating angiotensin II in rats. RUPP increased neural and microglial activation. Cellular localization assessment revealed that AT1R was primarily expressed in neurons and slightly in microglia and astrocytes. Infusion of 100 ng/kg as bolus increased the mean arterial pressure (MAP in mmHg) in both RUPP and Sham. ICV losartan infusion attenuated RUPP-increased MAP (113.6 ± 6.22 in RUPP vs. 92.16 ± 5.30 in RUPP + Los, p = 0.021) and the expression of nuclear transcription factor NF-κB, tyrosine hydroxylase (TH), NADPH oxidase 4 (NOX4) and reactive oxygen species (ROS) in the PVN. Our data suggest that centrally expressed AT1R, within the PVN, contributes to placental ischemia-induced hypertension in RUPP rats highlighting its therapeutic potential in PE.

The central mechanisms of electroacupuncture at LR3 in the treatment of spontaneous hypertension: a PET and mRNA transcriptome study

Objective

To reveal the efficacy and potential mechanisms of electroacupuncture (EA) in treating hypertension.

Methods

Male spontaneously hypertensive rats (SHRs) were randomly assigned to the SHR group, EA group, and Sham-EA group, with Wistar-Kyoto rats (WKY) as the normal control group. SHRs in the EA group received electroacupuncture at the bilateral Taichong (LR3) acupoints for 7 consecutive days. Evaluation of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) was conducted. Positron emission tomography-computed tomography (PET-CT) was employed to explore the active brain regions associated with acupuncture-induced blood pressure reduction. Furthermore, mRNA expression profiling was analyzed in the active brain regions to identify differentially expressed genes, and quantitative polymerase chain reaction (qPCR) was used to validate the mRNA expression of differentially expressed genes in the active brain region.

Results

EA reduced elevated SBP, DBP, MAP and HR in SHR. PET-CT revealed that EA decreased glucose metabolism in the hypothalamus. Genomic analysis suggested that, compared to the SHR group, the differentially expressed genes in the hypothalamus of the EA group included Nr4a1, Sirt1, Trh, GPR88, Cck, and Th. EA downregulated the mRNA expression of Th, Trh, Gpr88, and Nr4a1, while upregulating the expression of Sirt1 and Cck at the mRNA level.

Conclusion

EA may exert a unique antihypertensive effect in the hypothalamus of SHR, involving the modulation of sympathetic nerve activity, neuroinflammation, and oxidative stress response.

Effects of Probiotics on Inflammatory Biomarkers and Its Associations With Cardiac Autonomic Function in Women With Arterial Hypertension: A Secondary Analysis of a Randomized Clinical Trial

Preclinical evidence suggests that probiotic administration may exert an anti-inflammatory effect and reduce autonomic dysfunction and blood pressure. This study evaluated the effects of probiotic therapy on inflammatory biomarkers and characterized the correlations between inflammation and cardiac autonomic function in women with arterial hypertension. Women were randomized into probiotics (n = 20) or placebo (n = 20). The probiotic group received 109 CFU/day of Lactobacillus (L.) paracasei LPC-37, L. rhamnosus HN001, L. acidophilus NCFM, and Bifidobacterium lactis HN019, and the placebo group received polydextrose. Clinical, electrocardiogram, heart rate variability (HRV) analysis, and cytokine levels were assessed at baseline and after 8 weeks. Women who received probiotics for 8 weeks had increased serum levels of IL-17A (p = 0.02) and decreased INF-γ (p = 0.02) compared to baseline. Probiotic supplementation increased serum levels of IL-10 compared to the placebo group (p = 0.03). Probiotic or placebo administration did not change serum levels of TNFα and IL-6. Serum levels of IL-2 (p = 0.001, and p = 0.001) and IL-4 (p = 0.001, and p = 0.001) were reduced in women receiving placebo or probiotics, respectively. Correlations between HRV indices and inflammatory variables showed that INF-γ was positively correlated with heart rate (HR) and sympathetic HRV indices and negatively correlated with vagal HRV indices. IL-10 was negatively correlated with HR and sympathetic HRV indices. IL-6 was negatively correlated with parasympathetic HRV indices and positively correlated with SD2/SD1 ratio. Probiotic therapy has a discreet anti-inflammatory effect in hypertensive women, and pro-inflammatory cytokines were negatively correlated with vagal modulation and positively correlated with sympathetic modulation of HRV. The clinical trial was registered in the Brazilian Registry of Clinical Trials (ReBEC) with the identification RBR-9mj2dt.

A Narrative Review on the Clinical Relevance of Imaging the Circumventricular Brain Organs and Performing Their Anatomical and Histopathological Examination in Acute and Postacute COVID-19

ABSTRACT

Autopsy followed by histopathological examination is foundational in clinical and forensic medicine for discovering and understanding pathological changes in disease, their underlying processes, and cause of death. Imaging technology has become increasingly important for advancing clinical research and practice, given its noninvasive, in vivo and ex vivo applicability. Medical and forensic autopsy can benefit greatly from advances in imaging technology that lead toward minimally invasive, whole-brain virtual autopsy. Brain autopsy followed by histopathological examination is still the hallmark for understanding disease and a fundamental modus operandi in forensic pathology and forensic medicine, despite the fact that its practice has become progressively less frequent in medical settings. This situation is especially relevant with respect to new diseases such as COVID-19 caused by the SARS-CoV-2 virus, for which our neuroanatomical knowledge is sparse. In this narrative review, we show that ad hoc clinical autopsies and histopathological analyses combined with neuroimaging of the principal circumventricular organs are critical to gaining insight into the reconstruction of the pathophysiological mechanisms and the explanation of cause of death (ie, atrium mortis) related to the cardiovascular effects of SARS-CoV-2 infection in forensic and clinical medicine.

Induction of Neuroinflammation and Brain Oxidative Stress by Brain-Derived Extracellular Vesicles from Hypertensive Rats

Neuroinflammation and brain oxidative stress are recognized as significant contributors to hypertension including salt sensitive hypertension. Extracellular vesicles (EVs) play an essential role in intercellular communication in various situations, including physiological and pathological ones. Based on this evidence, we hypothesized that EVs derived from the brains of hypertensive rats with salt sensitivity could trigger neuroinflammation and oxidative stress during hypertension development. To test this hypothesis, we compared the impact of EVs isolated from the brains of hypertensive Dahl Salt-Sensitive rats (DSS) and normotensive Sprague Dawley (SD) rats on inflammatory factors and mitochondrial reactive oxygen species (mtROS) production in primary neuronal cultures and brain cardiovascular relevant regions, including the hypothalamic paraventricular nucleus (PVN) and lamina terminalis (LT). We found that brain-derived DSS-EVs significantly increased the mRNA levels of proinflammatory cytokines (PICs) and chemokines, including TNFα, IL1β, CCL2, CCL5, and CCL12, as well as the transcriptional factor NF-κB in neuronal cultures. DSS-EVs also induced oxidative stress in neuronal cultures, as evidenced by elevated NADPH oxidase subunit CYBA coding gene mRNA levels and persistent mtROS elevation. When DSS-EVs were injected into the brains of normal SD rats, the mRNA levels of PICs, chemokines, and the chronic neuronal activity marker FOSL1 were significantly increased in the PVN and LT. Furthermore, DSS-EVs caused mtROS elevation in brain PVN and LT, particularly in neurons. Our study reveals a novel role for brain-derived EVs from hypertensive rats in triggering neuroinflammation, upregulating chemokine expression, and inducing excessive ROS production. These findings provide insight into the complex interactions between EVs and hypertension-associated processes, offering potential therapeutic targets for hypertension-linked neurological complications.

Low-intensity pulsed ultrasound treatment mitigates ventricular arrhythmias via inhibiting microglia-mediated neuroinflammation in heart failure rat model

BACKGROUND

Sympathetic overactivation plays an important role in heart failure (HF)-induced ventricular arrhythmias (VAs). Microglia-mediated neuroinflammation could contribute to sympathetic overactivation. A previous study demonstrated that low-intensity pulsed ultrasound (LIPUS) could inhibit neuroinflammation. However, whether LIPUS could attenuate HF-induced VAs via inhibiting microglia-mediated neuroinflammation remains largely unknown.

METHODS

Forth Sprague-Dawley male rats were averagely randomized into four groups: CTL (control) group, CTL + LIPUS group, HF group and HF + LIPUS. Surgical ligation of the coronary artery was used for induction of HF. In vivo electrophysiological study was performed to check VAs susceptibility. Left stellate ganglion (LSG) neural activity and heart rate variability (HRV) were used to test sympathetic nerve activity.

RESULTS

Compared to the HF group, LIPUS treatment significantly ameliorated HF-induced cardiac hypertrophy, fibrosis, and dysfunction. In addition, LIPUS treatment markedly inhibited HF-induced VAs susceptibility and reversed gap junction remodeling. LIPUS treatment obviously inhibited microglial activation and neuroinflammation in PVN, sympathetic hyperactivity in the LSG and proinflammatory cytokines releases in the ventricle. P2X7/NLRP3 signaling pathway may be involved in the anti-arrhythmic effect of LIPUS treatment following HF.

CONCLUSIONS

Our data demonstrated that LIPUS treatment protected against HF-induced VAs via alleviating microglia-mediated neuroinflammation, sympathetic overactivation and proinflammatory cytokines releases through inhibiting P2X7/NLRP3 signaling. This study provides novel insight into the therapeutic potential of LIPUS.

Novel insight into cGAS-STING pathway in ischemic stroke: from pre- to post-disease

Ischemic stroke, a primary cause of disability and the second leading cause of mortality, has emerged as an urgent public health issue. Growing evidence suggests that the Cyclic GMP-AMP synthase (cGAS)- Stimulator of interferon genes (STING) pathway, a component of innate immunity, is closely associated with microglia activation, neuroinflammation, and regulated cell death in ischemic stroke. However, the mechanisms underlying this pathway remain inadequately understood. This article comprehensively reviews the existing literature on the cGAS-STING pathway and its multifaceted relationship with ischemic stroke. Initially, it examines how various risk factors and pre-disease mechanisms such as metabolic dysfunction and senescence (e.g., hypertension, hyperglycemia, hyperlipidemia) affect the cGAS-STING pathway in relation to ischemic stroke. Subsequently, we explore in depth the potential pathophysiological relationship between this pathway and oxidative stress, endoplasmic reticulum stress, neuroinflammation as well as regulated cell death including ferroptosis and PANoptosis following cerebral ischemia injury. Finally, it suggests that intervention targeting the cGAS-STING pathway may serve as promising therapeutic strategies for addressing neuroinflammation associated with ischemic stroke. Taken together, this review concludes that targeting the microglia cGAS-STING pathway may shed light on the exploration of new therapeutic strategies against ischemic stroke.

Bidirectional association between Parkinson's disease and obstructive sleep apnea: a cohort study

STUDY OBJECTIVES

Chronic intermittent hypoxia due to obstructive sleep apnea (OSA) causes oxidative stress, which may contribute to the pathophysiology of Parkinson's disease (PD). However, the bidirectional relationship between PD and OSA has not been satisfactorily established. The objective of this study was to try to estimate whether there is a bidirectional relationship between PD and OSA through a retrospective cohort study in the South Korean population.

METHODS

This study used data from the Korean National Health Information Database of the National Health Insurance Service, which contains data from 3.5 million individuals evenly distributed. In study 1, patients with OSA were matched in a 1:2 ratio with non-OSA controls. In study 2, patients with PD were matched in a 1:2 ratio with non-PD controls. A stratified Cox proportional hazards model was used to calculate hazard ratios.

RESULTS

In study 1, which included 6,396 patients with OSA and 12,792 non-OSA controls, the incidence of PD per 10,000 person-years was 11.59 in the OSA group and 8.46 in the non-OSA group. The OSA group demonstrated a 1.54-fold higher incidence of PD than the non-OSA group (95% confidence interval, 1.14-2.07; P < .05). In study 2, which included 3,427 patients with PD and 6,854 non-PD controls, the incidence of OSA per 10,000 person-years was 14.97 in the PD group and 7.72 in the non-PD group. The PD group demonstrated a 1.92-fold higher incidence of OSA than the non-PD group (95% confidence interval, 1.32-2.78; P < .05).

CONCLUSIONS

This study supports a possible bidirectional relationship between PD and OSA.

CITATION

Jeon S-H, Hwang YS, Oh S-Y, et al. Bidirectional association between Parkinson's disease and obstructive sleep apnea: a cohort study. J Clin Sleep Med. 2023;19(9):1615-1623.

Heat of the night: sleep disturbance activates inflammatory mechanisms and induces pain in rheumatoid arthritis

Sleep has a homeostatic role in the regulation of the immune system and serves to constrain activation of inflammatory signalling and expression of cellular inflammation. In patients with rheumatoid arthritis (RA), a misaligned inflammatory profile induces a dysregulation of sleep-wake activity, which leads to excessive inflammation and the induction of increased sensitivity to pain. Given that multiple biological mechanisms contribute to sleep disturbances (such as insomnia), and that the central nervous system communicates with the innate immune system via neuroendocrine and neural effector pathways, potential exists to develop prevention opportunities to mitigate the risk of insomnia in RA. Furthermore, understanding these risk mechanisms might inform additional insomnia treatment strategies directed towards steering and reducing the magnitude of the inflammatory response, which together could influence outcomes of pain and disease activity in RA.

Clarification of hypertension mechanisms provided by the research of central circulatory regulation

Sympathoexcitation, under the regulatory control of the brain, plays a pivotal role in the etiology of hypertension. Within the brainstem, significant structures involved in the modulation of sympathetic nerve activity include the rostral ventrolateral medulla (RVLM), caudal ventrolateral medulla (CVLM), nucleus tractus solitarius (NTS), and paraventricular nucleus (paraventricular). The RVLM, in particular, is recognized as the vasomotor center. Over the past five decades, fundamental investigations on central circulatory regulation have underscored the involvement of nitric oxide (NO), oxidative stress, the renin-angiotensin system, and brain inflammation in regulating the sympathetic nervous system. Notably, numerous significant findings have come to light through chronic experiments conducted in conscious subjects employing radio-telemetry systems, gene transfer techniques, and knockout methodologies. Our research has centered on elucidating the role of NO and angiotensin II type 1 (AT1) receptor-induced oxidative stress within the RVLM and NTS in regulating the sympathetic nervous system. Additionally, we have observed that various orally administered AT1 receptor blockers effectively induce sympathoinhibition by reducing oxidative stress via blockade of the AT1 receptor in the RVLM of hypertensive rats. Recent advances have witnessed the development of several clinical interventions targeting brain mechanisms. Nonetheless, Future and further basic and clinical research are needed.

Neurochemical Basis of Inter-Organ Crosstalk in Health and Obesity: Focus on the Hypothalamus and the Brainstem

Precise neural regulation is required for maintenance of energy homeostasis. Essential to this are the hypothalamic and brainstem nuclei which are located adjacent and supra-adjacent to the circumventricular organs. They comprise multiple distinct neuronal populations which receive inputs not only from other brain regions, but also from circulating signals such as hormones, nutrients, metabolites and postprandial signals. Hence, they are ideally placed to exert a multi-tier control over metabolism. The neuronal sub-populations present in these key metabolically relevant nuclei regulate various facets of energy balance which includes appetite/satiety control, substrate utilization by peripheral organs and glucose homeostasis. In situations of heightened energy demand or excess, they maintain energy homeostasis by restoring the balance between energy intake and expenditure. While research on the metabolic role of the central nervous system has progressed rapidly, the neural circuitry and molecular mechanisms involved in regulating distinct metabolic functions have only gained traction in the last few decades. The focus of this review is to provide an updated summary of the mechanisms by which the various neuronal subpopulations, mainly located in the hypothalamus and the brainstem, regulate key metabolic functions.

Study on material basis and anti-hypertensive metabolomics of different extraction methods of the Uncaria rhynchophylla Scrophularia Formula

Hypertension is one of the most challenging public health problems worldwide. Previous studies suggested that the Uncaria rhynchophylla Scrophularia Formula (URSF), a medical institution preparation of the affiliated Hospital of Shandong University of Traditional Chinese Medicine, is effective for essential hypertension. However, the efficacy of URSF for hypertension remains unclear. We aimed to clarify the anti-hypertensive mechanism of the URSF. The material basis of URSF was identified by the LC-MS. We also evaluated the antihypertensive efficacy of URSF on SHR rats by body weight, blood pressure and biochemical indicators. The LC-MS spectrometry-based serum non-targeted metabolomics was used to seek potential biomarkers and relevant pathways for URSF in the treatment of SHR rats. 56 biomarkers were metabolically disturbed in SHR rats in the model group compared with the control group. After URSF intervention, 13 biomarkers showed a recovery in the optimal method compared with the other three groups. We identified 3 metabolic pathways in which URSF is involved: the arachidonic acid metabolism pathway, the niacin and nicotinamide metabolism pathway, and the purine metabolism pathway. These discoveries offer a basis for the study of URSF for the treatment of hypertension.

Antioxidant Cascade Nanoenzyme Antagonize Inflammatory Pain by Modulating MAPK/p-65 Signaling Pathway

Chronic pain has attracted wide interest because it is a major obstacle affecting the quality of life. Consequently, safe, efficient, and low-addictive drugs are highly desirable. Nanoparticles (NPs) with robust anti-oxidative stress and anti-inflammatory properties possess therapeutic possibilities for inflammatory pain. Herein, a bioactive zeolitic imidazolate framework (ZIF)-8-capped superoxide dismutase (SOD) and Fe3 O4 NPs (SOD&Fe3 O4 @ZIF-8, SFZ) is developed to achieve enhanced catalytic, antioxidative activities, and inflammatory environment selectivity, ultimately improving analgesic efficacy. SFZ NPs reduce tert-butyl hydroperoxide (t-BOOH)-induced reactive oxygen species (ROS) overproduction, thereby depressing the oxidative stress and inhibiting the lipopolysaccharide (LPS)-induced inflammatory response in microglia. After intrathecal injection, SFZ NPs efficiently accumulate at the lumbar enlargement of the spinal cord and significantly relieve complete Freund's adjuvant (CFA)-induced inflammatory pain in mice. Moreover, the detailed mechanism of inflammatory pain therapy via SFZ NPs is further studied, where SFZ NPs inhibit the activation of the mitogen-activated protein kinase (MAPK)/p-65 signaling pathway, leading to reductions in phosphorylated protein levels (p-65, p-ERK, p-JNK, and p-p38) and inflammatory factors (tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-1β), thereby preventing microglia and astrocyte activation for acesodyne. This study provides a new cascade nanoenzyme for antioxidant treatments and explores its potential applications as non-opioid analgesics.

The role of (pro)renin receptor and its soluble form in cardiovascular diseases

The renin-angiotensin system (RAS) is a major classic therapeutic target for cardiovascular diseases. In addition to the circulating RAS, local tissue RAS has been identified in various tissues and plays roles in tissue inflammation and tissue fibrosis. (Pro)renin receptor (PRR) was identified as a new member of RAS in 2002. Studies have demonstrated the effects of PRR and its soluble form in local tissue RAS. Moreover, as an important part of vacuolar H⁺-ATPase, it also contributes to normal lysosome function and cell survival. Evidently, PRR participates in the pathogenesis of cardiovascular diseases and may be a potential therapeutic target of cardiovascular diseases. This review focuses on the effects of PRR and its soluble form on the physiological state, hypertension, myocardial ischemia reperfusion injury, heart failure, metabolic cardiomyopathy, and atherosclerosis. We aimed to investigate the possibilities and challenges of PRR and its soluble form as a new therapeutic target in cardiovascular diseases.

Neurogenic Hypertension, the Blood-Brain Barrier, and the Potential Role of Targeted Nanotherapeutics

Hypertension is a major health concern globally. Elevated blood pressure, initiated and maintained by the brain, is defined as neurogenic hypertension (NH), which accounts for nearly half of all hypertension cases. A significant increase in angiotensin II-mediated sympathetic nervous system activity within the brain is known to be the key driving force behind NH. Blood pressure control in NH has been demonstrated through intracerebrovascular injection of agents that reduce the sympathetic influence on cardiac functions. However, traditional antihypertensive agents lack effective brain permeation, making NH management extremely challenging. Therefore, developing strategies that allow brain-targeted delivery of antihypertensives at the therapeutic level is crucial. Targeting nanotherapeutics have become popular in delivering therapeutics to hard-to-reach regions of the body, including the brain. Despite the frequent use of nanotherapeutics in other pathological conditions such as cancer, their use in hypertension has received very little attention. This review discusses the underlying pathophysiology and current management strategies for NH, as well as the potential role of targeted therapeutics in improving current treatment strategies.

Role of blood-borne factors in sympathoexcitation-mediated hypertension: Potential neurally mediated hypertension in preeclampsia

Hypertension remains a threat for society due to its unknown causes, preventing proper management, for the growing number of patients, for its state as a high-risk factor for stroke, cardiac and renal complication and as cause of disability. Data from clinical and animal researches have suggested the important role of many soluble factors in the pathophysiology of hypertension through their neuro-stimulating effects. Central targets of these factors are of molecular, cellular and structural nature. Preeclampsia (PE) is characterized by high level of soluble factors with strong pro-hypertensive activity and includes immune factors such as proinflammatory cytokines (PICs). The potential neural effect of those factors in PE is still poorly understood. Shedding light into the potential central effect of the soluble factors in PE may advance our current comprehension of the pathophysiology of hypertension in PE, which will contribute to better management of the disease. In this paper, we summarized existing data in respect of hypothesis of this review, that is, the existence of the neural component in the pathophysiology of the hypertension in PE. Future studies would address this hypothesis to broaden our understanding of the pathophysiology of hypertension in PE.

Lactobacillus group and arterial hypertension: A broad review on effects and proposed mechanisms

Hypertension is the leading risk factor for cardiovascular diseases and is associated with intestinal dysbiosis with a decrease in beneficial microbiota. Probiotics can positively modulate the impaired microbiota and impart benefits to the cardiovascular system. Among them, the emended Lactobacillus has stood out as a microorganism capable of reducing blood pressure, being the target of several studies focused on managing hypertension. This review aimed to present the potential of Lactobacillus as an antihypertensive non-pharmacological strategy. We will address preclinical and clinical studies that support this proposal and the mechanisms of action by which these microorganisms reduce blood pressure or prevent its elevation.

Brain Interleukin-17A contributes to neuroinflammation and cardiac dysfunction in rats with myocardial infarction

Proinflammatory cytokines produced outside the central nervous system can act in the brain to promote sympathetic activation that contributes to the progression of heart failure (HF). Interleukin (IL)-17A, a key inflammatory regulator which orchestrates immune responses to promote chronic inflammation, has been implicated in the pathophysiology of HF. We previously reported that IL-17A acts within the brain, particularly in the hypothalamic paraventricular nucleus (PVN), to increase expression of inflammatory mediators and, consequently, sympathetic outflow. The present study sought to determine whether IL-17A levels are elevated in a rat model of HF induced by myocardial infarction and, if so, whether increased expression of IL-17A in the brain itself contributes to neuroinflammation and cardiac dysfunction in this disease setting. Male SD rats underwent coronary artery ligation (CL) to induce HF or sham operation (SHAM). Compared with SHAM rats, HF rats exhibited significantly increased IL-17A levels in plasma, beginning within 1 week with a peak increase at 4 weeks after CL. IL-17A levels in cerebrospinal fluid (CSF) were also increased in HF rats and correlated with IL-17A levels in the plasma. The mRNA expression of IL-17A and its receptor IL-17RA, but not IL-17RC, was markedly upregulated in the PVN of HF when compared with SHAM rats. Genetic knockdown of IL-17RA by bilateral PVN microinjections of an IL-17RA siRNA AAV virus attenuated mRNA expression of proinflammatory cytokines and chemokines, and ameliorated sympathetic activation and cardiac function in HF rats. These data indicate that elevated expression of IL-17A in the brain in HF contributes to the excessive central inflammatory state and cardiac dysfunction in HF. Interventions to suppress IL-17A/IL-17RA axis in the brain have the potential for treating HF.

Inhibition of cGAS in Paraventricular Nucleus Attenuates Hypertensive Heart Injury Via Regulating Microglial Autophagy

Neuroinflammation in the cardiovascular center plays a critical role in the progression of hypertensive heart disease. And microglial autophagy is involved in the regulation of neuroinflammation. Cyclic GMP-AMP synthase (cGAS), a cytosolic DNA sensor, senses mitochondrial DNA (mtDNA) and regulates autophagy. The detailed mechanisms of central cGAS affects neuroinflammatory response in hypertensive heart disease via regulating autophagy remain unknown. Angiotensin II (Ang II, 1.5 mg·kg⁻¹·12 h⁻¹, 2 weeks) was intraperitoneally injected to induce hypertension in mice. The cGAS-STING pathway was activated in the paraventricular nucleus (PVN) of Ang II-induced hypertensive mice. The contractile dysfunction of heart was alleviated in Ang II-induced hypertensive cGAS^−/− mice. To observe the central effects of cGAS on regulating hypertensive heart disease, the RU.521 (a cGAS inhibitor) was intracisternally infused in hypertensive mice. Intracisternal infusion of the RU.521-alleviated myocardial interstitial fibrosis, cardiomyocyte hypertrophy, and the contractile dysfunction in Ang II-induced hypertensive mice. Intracisternal infusion of RU.521 attenuated the microglial activation, neuroinflammation, sympathetic/parasympathetic activity ratio, and lowered blood pressure. The autophagic flux in the PVN cells was blocked, while intracisternal infusion of RU.521 alleviated this effect in the Ang II-induced hypertensive mice. In vitro, it was found that cGAS-STING activation-induced autophagic flux blockage, while when the impaired autophagic flux was facilitated by rapamycin, an autophagy inducer, the microglial M1 polarization was decreased correspondingly. In conclusion, cGAS induces the inflammatory phenotype of microglia via impairing autophagic flux, thereby participating in neuroinflammation, which leads to sympathetic overactivation in hypertension and further caused hypertensive myocardial injury.

Experimental verification and validation of immune biomarkers based on chromatin regulators in ischemic stroke

Ischemic stroke (IS) is a disease characterized by rapid progression and high mortality and disability rates. Its pathophysiological process is inseparable from immune dysfunction. Recently, chromatin regulators (CRs) have been described as a class of enzymes that can recognize, form, and maintain the epigenetic state of an organism, and are closely associated with immune regulation. Nevertheless, the role of CR-related genes in IS has not been fully elucidated. In this study, seven CR-related immune biomarkers in the GSE58294 and GSE22255 datasets were identified by combining differential gene expression analysis, weighted correlation network analysis, and single sample gene set enrichment analysis. After experimental validation using quantitative polymerase chain reaction, four genes (DPF2, LMNB1, MLLT3, and JAK2) were screened as candidate immune biomarkers. These four biomarkers demonstrated good predictive power in the clinical risk model (area under the curve, 0.775). Molecular docking simulations revealed that mevastatin, WP1066, cladribine, trichostatin A, mequitazine, and zuclomiphene may be potential immunomodulatory drugs for IS. Overall, the results of this study contribute to the identification of CR-related immune therapeutics target in IS and provide an important reference for further research.

Blood hemoglobin A1c might predict adverse differences in heart rate variability in a diabetic population: Evidence from the Midlife in the United States (MIDUS) study

Background

Cardiac autonomic neuropathy in population with diabetes mellitus (DM) is frequent and linked with high risk of cardiovascular mortality. However, studies on whether blood hemoglobin A1c (HbA1c) levels are related to adverse differences in heart rate variability (HRV) in individuals with DM are scarce.

Aim

We aimed to investigate the association of blood HbA1c levels with adverse differences in HRV, which is an indicator of cardiac autonomic control, in adult individuals with and without DM.

Methods

Data were collected from the Midlife in the United States (MIDUS) study, and 928 individuals were analyzed for the relationship between blood HbA1c levels and HRV through a cross-sectional analysis.

Results

Participants with DM had significantly higher HRV than those without DM. The smooth curve suggested inverse relationships between blood HbA1c levels and HF- and LF-HRV seen in participants with DM but not in those without DM after controlling for all covariates (age, sex, BMI, smoking, number of drinking years and exercise). Furthermore, linear regression analysis demonstrated that elevated blood HbA1c levels did contribute to adverse differences in HF-HRV (Sβ= -0.118; 95% CI -0.208, -0.027; P=0.012) and LF-HRV (Sβ= -0.097; 95% CI -0.177, -0.017; P=0.019) after controlling for these covariates in participants with DM, while in participants without DM, blood HbA1c was not significantly related to adverse differences in HF-HRV (Sβ=0.095; 95% CI -0.059, 0.248; P=0.228) or LF-HRV (Sβ=0.043; 95% CI -0.103, 0.189; P=0.565). DM has a significant modifying effect on associations between blood HbA1c and adverse differences in HF-HRV (P for interaction=0.019) and LF-HRV (P for interaction=0.029).

Conclusions

We reported strong evidence that elevated blood levels of HbA1c were associated with adverse differences in HRV in the diabetic population but not in the nondiabetic population. This finding supported that long-term hyperglycemia is related to autonomic nerve injury in the diabetic population. Blood HbA1c might be a good indicator of cardiac autonomic neuropathy.

Association of the Heart Rate Variability Response to Active Standing with the Severity of Calcific Aortic Valve Disease: Novel Insights of a Neurocardiovascular Pathology

The aim of this work was to obtain insights of the participation of the autonomic nervous system in different stages of calcific aortic valve disease (CAVD) by heart rate variability (HRV) analysis. Studying subjects with no valve impairments and CAVD patients, we also sought to quantify the independent contribution or explanatory capacity of the aortic valve echocardiographic parameters involved in the HRV changes caused by active standing using hierarchical partitioning models to consider other variables or potential confounders. We detected smaller adjustments of the cardiac autonomic response at active standing caused specifically by the aortic valve deterioration. The highest association (i.e., the highest percentage of independent exploratory capacity) was found between the aortic valve area and the active standing changes in the short-term HRV scaling exponent α₁ (4.591%). The valve’s maximum pressure gradient echocardiographic parameter was present in most models assessed (in six out of eight models of HRV indices that included a valve parameter as an independent variable). Overall, our study provides insights with a wider perspective to explore and consider CAVD as a neurocardiovascular pathology. This pathology involves autonomic-driven compensatory mechanisms that seem generated by the aortic valve deterioration.

Inhibition of Microbiota-dependent Trimethylamine N-Oxide Production Ameliorates High Salt Diet-Induced Sympathetic Excitation and Hypertension in Rats by Attenuating Central Neuroinflammation and Oxidative Stress

Excessive dietary salt intake induces neuroinflammation and oxidative stress in the brain, which lead to sympathetic excitation, contributing to hypertension. However, the underlying mechanisms remain elusive. Accumulating evidence reveals that trimethylamine-N-oxide (TMAO), a gut microbiota-derived metabolite, is implicated in the pathogenesis of multiple cardiovascular diseases. The present study sought to determine whether central TMAO is elevated and associated with neuroinflammation and oxidative stress in the brain after long-term high salt (HS) diet intake and, if so, whether inhibition of TMAO generation ameliorates HS-induced sympathetic excitation and hypertension. Sprague-Dawley rats were fed either a HS diet or a normal salt (NS) diet and simultaneously treated with vehicle (VEH) or 1.0% 3,3-Dimethyl-1-butanol (DMB, an inhibitor of trimethylamine formation) for 8 weeks. HS + VEH rats, compared with NS + VEH rats, had elevated TMAO in plasma and cerebrospinal fluid (CSF), increased blood pressure (BP), and increased sympathetic drive as indicated by the BP response to ganglionic blockade and plasma norepinephrine levels. HS-induced these changes were attenuated by DMB, which significantly reduced TMAO in plasma and CSF. Neuroinflammation as assessed by proinflammatory cytokine expression and NF-κB activity and microglial activity, and oxidative stress as measured by NAD(P)H oxidase subunit expression and NAD(P)H activity and reactive oxygen species (ROS) production in the hypothalamic paraventricular nucleus (PVN) were increased in HS + VEH rats but were decreased by DMB. DMB had no effects on above measured parameters in NS rats. The results suggest that long-term HS diet intake causes elevation in TMAO in the circulation and brain, which is associated with increased neuroinflammation and oxidative stress in the PVN, an important cardiovascular regulatory center. Inhibition of TMAO generation ameliorates HS-induced sympathetic excitation and hypertension by reducing neuroinflammation and oxidative stress in the PVN.

Voluntary Exercise Prevents Hypertensive Response Sensitization Induced by Angiotensin II

Exercise training has profound effects on the renin-angiotensin system, inflammatory cytokines and oxidative stress, all of which affect autonomic nervous system activity and regulate blood pressure (BP) in both physiological and pathophysiological states. Using the Induction-Delay-Expression paradigm, our previous studies demonstrated that various challenges (stressors) during Induction resulted in hypertensive response sensitization (HTRS) during Expression. The present study tested whether voluntary exercise would protect against subpressor angiotensin (ANG) II-induced HTRS in rats. Adult male rats were given access to either “blocked” (sedentary rats) or functional running (exercise rats) wheels for 12 weeks, and the Induction-Delay-Expression paradigm was applied for the rats during the last 4 weeks. A subpressor dose of ANG II given during Induction produced an enhanced hypertensive response to a pressor dose of ANG II given during Expression in sedentary rats in comparison to sedentary animals that received saline (vehicle control) during Induction. Voluntary exercise did not attenuate the pressor dose of ANG II-induced hypertension but prevented the expression of HTRS seen in sedentary animals. Moreover, voluntary exercise reduced body weight gain and feed efficiency, abolished the augmented BP reduction after ganglionic blockade, reversed the increased mRNA expression of pro-hypertensive components, and upregulated mRNA expression of antihypertensive components in the lamina terminalis and hypothalamic paraventricular nucleus, two key brain nuclei involved in the control of sympathetic activity and BP regulation. These results indicate that exercise training plays a beneficial role in preventing HTRS and that this is associated with shifting the balance of the brain prohypertensive and antihypertensive pathways in favor of attenuated central activity driving sympathetic outflow and reduced BP.

The Bidirectional Signal Communication of Microbiota-Gut-Brain Axis in Hypertension

Hypertension is a critical risk factor of cardiovascular diseases. A new concept of microbiota-gut-brain axis has been established recently, mediating the bidirectional communication between the gut and its microbiome and the brain. Alterations in bidirectional interactions are believed to be involved in the blood pressure regulation. Neuroinflammation and increased sympathetic outflow act as the descending innervation signals from the brain. Increased sympathetic activation plays a recognized role in the genesis of hypertension. The present evidence demonstrates that gut dysbiosis is associated with central nervous system neuroinflammation. However, how the gut influences the brain remains unclear. We reviewed the roles of neuroinflammation and gut microbiota and their interactions in the pathogenesis of hypertension and described the ascending signaling mechanisms behind the microbiota-gut-brain axis in detail. Additionally, the innovative prohypertensive mechanisms of dietary salt through the microbiota-gut-brain axis are summarized. The bidirectional communication mechanisms were proposed for the first time that the descending signals from the brain and the ascending connections from the gut form a vicious circle of hypertension progression, acting as a premise for hypertension therapy.

Effects of β-Blockers on the Sympathetic and Cytokines Storms in Covid-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a causative virus in the development of coronavirus disease 2019 (Covid-19) pandemic. Respiratory manifestations of SARS-CoV-2 infection such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) leads to hypoxia, oxidative stress, and sympatho-activation and in severe cases leads to sympathetic storm (SS). On the other hand, an exaggerated immune response to the SARS-CoV-2 invasion may lead to uncontrolled release of pro-inflammatory cytokine development of cytokine storm (CS). In Covid-19, there are interactive interactions between CS and SS in the development of multi-organ failure (MOF). Interestingly, cutting the bridge between CS and SS by anti-inflammatory and anti-adrenergic agents may mitigate complications that are induced by SARS-CoV-2 infection in severely affected Covid-19 patients. The potential mechanisms of SS in Covid-19 are through different pathways such as hypoxia, which activate the central sympathetic center through carotid bodies chemosensory input and induced pro-inflammatory cytokines, which cross the blood-brain barrier and activation of the sympathetic center. β2-receptors signaling pathway play a crucial role in the production of pro-inflammatory cytokines, macrophage activation, and B-cells for the production of antibodies with inflammation exacerbation. β-blockers have anti-inflammatory effects through reduction release of pro-inflammatory cytokines with inhibition of NF-κB. In conclusion, β-blockers interrupt this interaction through inhibition of several mediators of CS and SS with prevention development of neural-cytokine loop in SARS-CoV-2 infection. Evidence from this study triggers an idea for future prospective studies to confirm the potential role of β-blockers in the management of Covid-19.

Case Report: Miles Surgery Ameliorates High Blood Pressure in a Rectal Carcinoma Patient With Essential Hypertension

Hypertension is one of the major causes of public health problems. Multiple factors affecting gastrointestinal tract function are involved in hypertension. Emerging studies have manifested that gut intervention may play significant roles in regulating blood pressure but the underlying mechanisms are complex and not fully clear. Here, we report a case of 66 years old male who had a long history of hypertension and received Miles surgery for rectal carcinoma. The blood pressure of this patient was returned to normal levels after the operation. The possible reasons could be the modulation of sympathetic tone and the gut microbiota-brain axis. This report provides evidence about the relevance between hypertension and gut intervention particularly in the colorectal sites and gives hints for investigating the possible mechanisms of hypertension and the novel strategy for blood pressure control.

Angiotensin II and the Cardiac Parasympathetic Nervous System in Hypertension

The renin-angiotensin-aldosterone system (RAAS) impacts cardiovascular homeostasis via direct actions on peripheral blood vessels and via modulation of the autonomic nervous system. To date, research has primarily focused on the actions of the RAAS on the sympathetic nervous system. Here, we review the critical role of the RAAS on parasympathetic nerve function during normal physiology and its role in cardiovascular disease, focusing on hypertension. Angiotensin (Ang) II receptors are present throughout the parasympathetic nerves and can modulate vagal activity via actions at the level of the nerve endings as well as via the circumventricular organs and as a neuromodulator acting within brain regions. There is tonic inhibition of cardiac vagal tone by endogenous Ang II. We review the actions of Ang II via peripheral nerve endings as well as via central actions on brain regions. We review the evidence that Ang II modulates arterial baroreflex function and examine the pathways via which Ang II can modulate baroreflex control of cardiac vagal drive. Although there is evidence that Ang II can modulate parasympathetic activity and has the potential to contribute to impaired baseline levels and impaired baroreflex control during hypertension, the exact central regions where Ang II acts need further investigation. The beneficial actions of angiotensin receptor blockers in hypertension may be mediated in part via actions on the parasympathetic nervous system. We highlight important unknown questions about the interaction between the RAAS and the parasympathetic nervous system and conclude that this remains an important area where future research is needed.

Short-lived sensitization of cardiovascular outcomes of postpartum endotoxemia in preeclamptic rats: Role of medullary solitary tract neuroinflammation

Preeclampsia (PE) is a pregnancy-related disorder with serious maternal complications. Considering the increased importance of postpartum infection in maternal morbidity and mortality, we investigated whether preeclamptic maternal programming alters cardiovascular consequences of endotoxemia in rats and the role of cardiac and brainstem neuroinflammation in this interaction. Preeclampsia was induced by oral administration of L-NAME (50 mg/kg/day) for 7 days starting from day 14 of conception. Changes in blood pressure, heart rate, and cardiac autonomic function caused by lipopolysaccharide (LPS, 5 mg/kg i.v.) were assessed in mothers at 3 weeks (weaning time) and 9 weeks postnatally. Compared with respective non-PE counterparts, LPS treatment of weaning PE mothers caused significantly greater (i) falls in blood pressure, (ii) rises in heart rate and left ventricular contractility (dP/dtmax), (iii) reductions in time and frequency domain indices of heart rate variability and shifts in cardiac sympathovagal balance (low-frequency/high-frequency ratio, LF/HF) towards parasympathetic dominance, and (iv) attenuation of reflex bradycardic responses measured by the vasoactive method. The intensified LPS effects in weaning PE rats subsided after 9 weeks of delivery. Immunohistochemical studies showed increased protein expression of nuclear factor kappa B (NF-κB) in brainstem neuronal pools of the nucleus of the solitary tract (NTS), but not rostral ventrolateral medulla (RVLM), in endotoxic PE weaning rats compared with non-PE rats. Cardiac NF-κB expression was increased by LPS but this was similarly noted in PE and non-PE rats. Together, preeclamptic maternal programming elicits short-term exacerbation of endotoxic cardiovascular and autonomic derangements due possibly to exaggerated NTS neuroinflammatory insult.

IL (Interleukin)-17A Acts in the Brain to Drive Neuroinflammation, Sympathetic Activation, and Hypertension

[Figure: see text].

Apigenin Improves Hypertension and Cardiac Hypertrophy Through Modulating NADPH Oxidase-Dependent ROS Generation and Cytokines in Hypothalamic Paraventricular Nucleus

Apigenin, identified as 4', 5, 7-trihydroxyflavone, is a natural flavonoid compound that has many interesting pharmacological activities and nutraceutical potential including anti-inflammatory and antioxidant functions. Chronic, low-grade inflammation and oxidative stress are involved in both the initiation and progression of hypertension and hypertension-induced cardiac hypertrophy. However, whether or not apigenin improves hypertension and cardiac hypertrophy through modulating NADPH oxidase-dependent reactive oxygen species (ROS) generation and inflammation in hypothalamic paraventricular nucleus (PVN) has not been reported. This study aimed to investigate the effects of apigenin on hypertension in spontaneously hypertensive rats (SHRs) and its possible central mechanism of action. SHRs and Wistar-Kyoto (WKY) rats were randomly assigned and treated with bilateral PVN infusion of apigenin or vehicle (artificial cerebrospinal fluid) via osmotic minipumps (20 μg/h) for 4 weeks. The results showed that after PVN infusion of apigenin, the mean arterial pressure (MAP), heart rate, plasma norepinephrine (NE), Beta 1 receptor in kidneys, level of phosphorylation of PKA in the ventricular tissue and cardiac hypertrophy, perivascular fibrosis, heart level of oxidative stress, PVN levels of oxidative stress, interleukin 1β (IL-1β), interleukin 6 (IL-6), iNOS, monocyte chemotactic protein 1 (MCP-1), tyrosine hydroxylase (TH), NOX2 and NOX4 were attenuated and PVN levels of interleukin 10 (IL-10), superoxide dismutase 1 (Cu/Zn-SOD) and the 67-kDa isoform of glutamate decarboxylase (GAD67) were increased. These results revealed that apigenin improves hypertension and cardiac hypertrophy in SHRs which are associated with the down-regulation of NADPH oxidase-dependent ROS generation and inflammation in the PVN.

Anti-apoptotic and pro-survival effect of exercise training on early aged hypertensive rat cerebral cortex

The anti-apoptotic and pro-survival effects of exercise training were evaluated on the early aged hypertensive rat cerebral cortex. The brain tissues were analysed from ten sedentary male Wistar Kyoto normotensive rats (WKY), ten sedentary spontaneously 12 month early aged hypertensive rats (SHR), and ten hypertensive rats undergoing treadmill exercise training (60 min/day, 5 days/week) for 12 weeks (SHR-EX). TUNEL-positive apoptotic cells, the expression levels of endonuclease G (EndoG) and apoptosis-inducing factor (AIF) (caspase-independent apoptotic pathway), Fas ligand, Fas death receptor, tumor necrosis factor (TNF)-α, TNF receptor 1, Fas-associated death domain, active caspase-8 and active caspase-3 (Fas-mediated apoptotic pathways) as well as t-Bid, Bax, Bak, Bad, cytochrome c, active caspase 9 and active caspase-3 (mitochondria-mediated apoptotic pathways) were reduced in SHR-EX compared with SHR. Pro-survival Bcl2, Bcl-xL, p-Bad, 14-3-3, insulin-like growth factor (IGF)-1, pPI3K/PI3K, and pAKT/AKT were significantly increased in SHR-EX compared to those in SHR. Exercise training suppressed neural EndoG/AIF-related caspase-independent, Fas/FasL-mediated caspase-dependent, mitochondria-mediated caspase-dependent apoptotic pathways as well as enhanced Bcl-2 family-related and IGF-1-related pro-survival pathways in the early aged hypertensive cerebral cortex. These findings indicated new therapeutic effects of exercise training on preventing early aged hypertension-induced neural apoptosis in cerebral cortex.

Age-related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review

The process of aging includes changes in cellular biology that affect local interactions between cells and their environments and eventually propagate to systemic levels. In the brain, where neurons critically depend on an efficient and dynamic supply of oxygen and glucose, age-related changes in the complex interaction between the brain parenchyma and the cerebrovasculature have effects on health and functioning that negatively impact cognition and play a role in pathology. Thus, cerebrovascular health is considered one of the main mechanisms by which a healthy lifestyle, such as habitual cardiorespiratory exercise and a healthful diet, could lead to improved cognitive outcomes with aging. This review aims at detailing how the physiology of the cerebral vascular system changes with age and how these changes lead to differential trajectories of cognitive maintenance or decline. This provides a framework for generating specific mechanistic hypotheses about the efficacy of proposed interventions and lifestyle covariates that contribute to enhanced cognitive well-being. Finally, we discuss the methodological implications of age-related changes in the cerebral vasculature for human cognitive neuroscience research and propose directions for future experiments aimed at investigating age-related changes in the relationship between physiology and cognitive mechanisms.

Contrasting Roles of Ang II and ACEA in the Regulation of IL10 and IL1β Gene Expression in Primary SHR Astroglial Cultures

Angiotensin (Ang) II is well-known to have potent pro-oxidant and pro-inflammatory effects in the brain. Extensive crosstalk between the primary Ang II receptor, Ang type 1 receptor (AT1R), and the cannabinoid type 1 receptor (CB1R) has been demonstrated by various groups in the last decade. Since activation of glial CB1R has been demonstrated to play a key role in the resolution of inflammatory states, we investigated the role of Ang II (100 nM) and/or ACEA (10 nM), a potent CB1R-specific agonist in the regulation of inflammatory markers in astrocytes from spontaneously hypertensive rats (SHR) and Wistar rats. Astrocytes were cultured from brainstems and cerebellums of SHR and Wistar rats and assayed for IL1β and IL10 gene expression and secreted fraction, in treated and non-treated cells, by employing qPCR and ELISA, respectively. mRNA expression of both IL10 and IL1β were significantly elevated in untreated brainstem and cerebellar astrocytes isolated from SHR when compared to Wistar astrocytes. No changes were observed in the secreted fraction. While ACEA-treatment resulted in a significant increase in IL10 gene expression in Wistar brainstem astrocytes (Log2FC ≥ 1, p < 0.05), its effect in SHR brainstem astrocytes was diminished. Ang II treatment resulted in a strong inhibitory effect on IL10 gene expression in astrocytes from both brain regions of SHR and Wistar rats (Log2FC ≤ -1, p < 0.05), and an increase in IL1β gene expression in brainstem astrocytes from both strains (Log2FC ≥ 1, p < 0.05). Co-treatment of Ang II and ACEA resulted in neutralization of Ang II-mediated effect in Wistar brainstem and cerebellar astrocytes, but not SHR astrocytes. Neither Ang II nor ACEA resulted in any significant changes in IL10 or IL1β secreted proteins. These data suggest that Ang II and ACEA have opposing roles in the regulation of inflammatory gene signature in astrocytes isolated from SHR and Wistar rats. This however does not translate into changes in their secreted fractions.

Neuropathology of the Brainstem to Mechanistically Understand and to Treat Alzheimer's Disease

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder as yet without effective therapy. Symptoms of this disorder typically reflect cortical malfunction with local neurohistopathology, which biased investigators to search for focal triggers and molecular mechanisms. Cortex, however, receives massive afferents from caudal brain structures, which do not only convey specific information but powerfully tune ensemble activity. Moreover, there is evidence that the start of AD is subcortical. The brainstem harbors monoamine systems, which establish a dense innervation in both allo- and neocortex. Monoaminergic synapses can co-release neuropeptides either by precisely terminating on cortical neurons or, when being “en passant”, can instigate local volume transmission. Especially due to its early damage, malfunction of the ascending monoaminergic system emerges as an early sign and possible trigger of AD. This review summarizes the involvement and cascaded impairment of brainstem monoaminergic neurons in AD and discusses cellular mechanisms that lead to their dysfunction. We highlight the significance and therapeutic challenges of transmitter co-release in ascending activating system, describe the role and changes of local connections and distant afferents of brainstem nuclei in AD, and summon the rapidly increasing diagnostic window during the last few years.

Effects of Aqueous Extract of Lycopersicum esculentum L. var. “Camone” Tomato on Blood Pressure, Behavior and Brain Susceptibility to Oxidative Stress in Spontaneously Hypertensive Rats

Behavioral disorders affect millions of people worldwide. Hypertension contributes to both the development and progression of brain damage and cognitive dysfunction and could represent the most powerful modifiable risk factor for cerebral vessel dysfunction and consequent behavioral impairment. Tomato contains antioxidants and bioactive molecules that might play an important role in the prevention of cardiovascular and brain diseases. The effects of the combined gel and serum from Lycopersicum esculentum L. var. “Camone” tomatoes and those of purified tomato glycoalkaloids (tomatine) and an antihypertensive drug (captopril) were investigated in male spontaneously hypertensive rats (SHRs) and compared with normotensive Wistar Kyoto (WKY) rats. Body weight, systolic blood pressure, behavioral parameters, as well as brain susceptibility to oxidative stress and brain cytokine contents, were assessed. Treating hypertensive rats with tomato gel/serum or captopril for four weeks caused a significant reduction in blood pressure, decreased locomotor activity and increased grooming behavior; the last two parameters were also significantly affected by tomatine treatment. Brain slices obtained from hypertensive rats treated with tomato gel/serum were more resistant to oxidative stress and contained lower levels of inflammatory cytokines than vehicle-treated ones. In contrast, tomatine treatment had no effect. In conclusion, the tomato-derived gel/serum can be considered a dietary supplement able to drive in vivo blood pressure towards healthier values and also control some central effects such as behavior and brain oxidative stress.

Paraventricular Nucleus Infusion of Oligomeric Proantho Cyanidins Improves Renovascular Hypertension

Oxidative stress plays an important role in the pathogenesis of hypertension. Oligomeric proantho cyanidins (OPC) is the main polyphenol presents in grape seed and is known for its potent antioxidant and anti-inflammatory properties. In the present study, we hypothesize that OPC can attenuate oxidative stress in the paraventricular nucleus of hypothalamus (PVN), ameliorate neurotransmitter imbalance, decrease the blood pressure and sympathetic activity in renovascular hypertensive rats. After induction of renovascular hypertension by the two-kidney one-clip (2K-1C) method, male Sprague-Dawley rats received chronic bilateral PVN infusion of OPC (20 μg/h) or vehicle via osmotic minipump for 4 weeks. We found that hypertension induced by 2K-1C was associated with the production of reactive oxygen species (ROS) in the PVN. Infusion of OPC in the PVN significantly reduced the systolic blood pressure and norepinephrine in plasma of 2K-1C rats. In addition, PVN infusion of OPC decreased the level of ROS and the expression of stress-related nicotinamide adenine dinucleotide phosphate (NADPH) oxidases subunit NOX4, increased the levels of nuclear factor E2-related factor 2 (Nrf2) and antioxidant enzyme, balanced the content of cytokines, increased expression of glutamic acid decarboxylase and decreased the expression of tyrosine hydroxylase in the PVN of 2K-1C rats. Our findings provided strong evidence that PVN infusion of OPC inhibited the progression of renovascular hypertension through its potent anti-oxidative and anti-inflammatory function in the PVN.

TNF-α-induced sympathetic excitation requires EGFR and ERK1/2 signaling in cardiovascular regulatory regions of the forebrain

Peripherally or centrally administered TNF-α elicits a prolonged sympathetically mediated pressor response, but the underlying molecular mechanisms are unknown. Activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in cardiovascular regions of the brain has recently been recognized as a key mediator of sympathetic excitation, and ERK1/2 signaling is induced by activation of epidermal growth factor receptor (EGFR) tyrosine kinase activity. The present study examined the role of EGFR and ERK1/2 signaling in the sympathetic response to TNF-α. In urethane-anesthetized rats, intracarotid artery injection of TNF-α increased phosphorylation of EGFR and ERK1/2 in the subfornical organ (SFO) and the hypothalamic paraventricular nucleus (PVN); upregulated the gene expression of excitatory mediators in SFO and PVN; and increased blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA). A continuous intracerebroventricular infusion of the selective EGFR tyrosine kinase inhibitor AG1478 or the ERK1/2 inhibitor PD98059 significantly attenuated these responses. Bilateral PVN microinjections of TNF-α also increased phosphorylated ERK1/2 and the gene expression of excitatory mediators in PVN, along with increases in BP, HR, and RSNA, and these responses were substantially reduced by prior bilateral PVN microinjections of AG1478. These results identify activation of EGFR in cardiovascular regulatory regions of the forebrain as an important molecular mediator of TNF-α-driven sympatho-excitatory responses and suggest that EGFR activation of the ERK1/2 signaling pathway plays an essential role. These mechanisms likely contribute to sympathetic excitation in pathophysiological states like heart failure and hypertension, in which circulating and brain TNF-α levels are increased.NEW & NOTEWORTHY Proinflammatory cytokines contribute to the augmented sympathetic nerve activity in hypertension and heart failure, but the central mechanisms involved are largely unknown. The present study reveals that TNF-α transactivates EGFR in the subfornical organ and the hypothalamic paraventricular nucleus to initiate ERK1/2 signaling, upregulate the gene expression of excitatory mediators, and increase sympathetic nerve activity. These findings identify EGFR as a gateway to sympathetic excitation and a potential target for intervention in cardiovascular disease states.

Recent advances in managing primary hypertension

Hypertension remains a leading risk factor for cardiovascular mortality and morbidity globally despite the availability of effective and well-tolerated antihypertensive medications. Accumulating evidence suggests a more aggressive blood pressure regulation aimed at lower targets, particularly for selected patient groups. Our concepts of the optimal method for blood pressure measurement have radically changed, maintaining appropriate standard office measurements for initial assessment but relying on out-of-office measurement to better guide our decisions. Thorough risk stratification provides guidance in decision making; however, an individualized approach is highly recommended to prevent overtreatment. Undertreatment, on the other hand, remains a major concern and is mainly attributed to poor adherence and resistant or difficult-to-control forms of the disease. This review aims to present modern perspectives, novel treatment options, including innovative technological applications and developing interventional and pharmaceutical therapies, and the major concerns emerging from several years of research and epidemiological observations related to hypertension management.

Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases

The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.

The importance of bone marrow and the immune system in driving increases in blood pressure and sympathetic nerve activity in hypertension

NEW FINDINGS

What is the topic of this review? This manuscript provides a review of the current understanding of the role of the sympathetic nervous system in regulation of bone marrow-derived immune cells and the effect that the infiltrating bone marrow cells may have on perpetuation of the sympathetic over-activation in hypertension. What advances does it highlight? We highlight the recent advances in understanding of the neuroimmune interactions both peripherally and centrally as they relate to blood pressure control.

ABSTRACT

The sympathetic nervous system (SNS) plays a crucial role in maintaining physiological homeostasis, in part by regulating, integrating and orchestrating processes between many physiological systems, including the immune system. Sympathetic nerves innervate all primary and secondary immune organs, and all cells of the immune system express β-adrenoreceptors. In turn, immune cells can produce cytokines, chemokines and neurotransmitters capable of modulating neuronal activity and, ultimately, SNS activity. Thus, the essential role of the SNS in the regulation of innate and adaptive immune functions is mediated, in part, via β-adrenoreceptor-induced activation of bone marrow cells by noradrenaline. Interestingly, both central and systemic inflammation are well-established hallmarks of hypertension and its co-morbidities, including an inflammatory process involving the transmigration and infiltration of immune cells into tissues. We propose that physiological states that prolong β-adrenoreceptor activation in bone marrow can disrupt neuroimmune homeostasis and impair communication between the immune system and SNS, leading to immune dysregulation, which, in turn, is sustained via a central mechanism involving neuroinflammation.

Light Emitting Diode Therapy Protects against Myocardial Ischemia/Reperfusion Injury through Mitigating Neuroinflammation

Background

Neuroinflammation plays a key role in myocardial ischemia-reperfusion (I/R) injury. Previous studies showed that light-emitting diode (LED) therapy might improve M2 microglia activation and brain-derived neurotrophic factor (BDNF) expression, thereby exerting anti-inflammatory effects. Therefore, we hypothesized that LED therapy might reduce myocardial I/R injury by neuroinflammation modulation.

Objective

To explore the effect of LED therapy on myocardial I/R-induced injury and seek the underlying mechanism.

Methods

Thirty rats were randomly divided into three groups: Control group (without LED treatment or myocardial I/R, n = 6), I/R group (with myocardial I/R only, n = 12), and LED+I/R group (with myocardial I/R and LED therapy, n = 12). Electrocardiogram was recorded continuously during the procedure. In addition, brain tissue was extracted for BDNF, Iba1, and CD206 analyses, and heart tissue for myocardial injury (ischemic size and infarct size), IL-4 and IL-10 mRNA analysis.

Results

In comparison with the I/R group, the ischemia size and the infarct size were significantly attenuated by LED therapy in the LED+I/R group. Meanwhile, the microglia activation induced by I/R injury was prominently attenuated by LED treatment either. And it is apparent that there was also an increase in the beneficial neuroinflammation markers (BDNF and CD206) in the paraventricular nucleus (PVN) in the LED+I/R group. Furthermore, the anti-inflammatory cytokines, IL-4 and IL-10, were greatly decreased by I/R while improved by LED treatment in myocardium.

Conclusion

LED therapy might reduce neuroinflammation in PVN and decrease myocardium injury by elevating BDNF and M2 microglia.

Cerebrovascular function in hypertension: Does high blood pressure make you old?

The majority of individuals over an age of 60 have hypertension. Elevated blood pressure and older age are associated with very similar changes in brain structure and function. We review the parallel brain changes associated with increasing age and blood pressure. This review focuses on joint associations of aging and elevated blood pressure with neuropsychological function, regional cerebral blood flow responses to cognitive and metabolic challenges, white matter disruptions, grey matter volume, cortical thinning, and neurovascular coupling. Treatment of hypertension ameliorates many of these changes but fails to reverse them. Treatment of hypertension itself appears more successful with better initial brain function. We show evidence that sympathetic and renal influences known to increase blood pressure also impact brain integrity. Possible central mechanisms contributing to the course of hypertension and aging are then suggested. An emphasis is placed on psychologically relevant factors: stress, cardiovascular reactions to stress, and diet/obesity. The contribution of some of these factors to biological aging remains unclear and may provide a starting point for defining the independent and interacting effects of aging and increasing blood pressure on the brain.

Diabetes, and its treatment, as an effector of autonomic nervous system circuits and its functions

Diabetes increases the risk of cardiovascular complications, including heart failure, hypertension, and stroke. There is a strong involvement of autonomic dysfunction in individuals with diabetes that exhibit clinical manifestations of cardiovascular diseases (CVD). Still, the mechanisms by which diabetes and its treatments alter autonomic function and subsequently affect cardiovascular complications remain elusive. For this reason, understanding the brainstem circuits involved in sensing metabolic state(s) and enacting autonomic control of the cardiovascular system are important to develop more comprehensive therapies for individuals with diabetes at increased risk for CVD. We review how autonomic nervous system circuits change during these disease states and discuss their potential role in current pharmacotherapies that target diabetic states. Overall, this review proposes that the brainstem circuits provide an integrative sensorimotor network capable of responding to metabolic cues to regulate cardiovascular function and this network is modified by, and in turn affects, diabetes-induced CVD and its treatment.

Interactions of the Brain Renin-Angiotensin-System (RAS) and Inflammation in the Sensitization of Hypertension

Mounting evidence indicates that the renin-angiotensin (RAS) and immune systems interact with one another in the central nervous system (CNS) and that they are importantly involved in the pathogenesis of hypertension. Components comprising the classic RAS were first identified in the periphery, and subsequently, similar factors were found to be generated de novo in many different organs including the brain. There is humoral-neural coupling between the systemic and brain RASs, which is important for controlling sympathetic tone and the release of endocrine factors that collectively determine blood pressure (BP). Similar to the interactions between the systemic and brain RASs is the communication between the peripheral and brain immune systems. Systemic inflammation activates the brain’s immune response. Importantly, the RAS and inflammatory factors act synergistically in brain regions involved in the regulation of BP. This review presents evidence of how such interactions between the brain RAS and central immune mechanisms contribute to the pathogenesis of hypertension. Emphasis focuses on the role of these interactions to induce neuroplastic changes in a central neural network resulting in hypertensive response sensitization (HTRS). Neuroplasticity and HTRS can be induced by challenges (stressors) presented earlier in life such as a low-dose of angiotensin II or high fat diet (HFD) feeding in adults. Similarly, the offspring of mothers with gestational hypertension or of mothers ingesting a HFD during pregnancy are reprogrammed and manifest HTRS when exposed to new stressors as adults. Consideration of the actions and interactions of the brain RAS and inflammatory mediators in the context of the induction and expression of HTRS will provide insights into the etiology of high BP that may lead to new strategies for the prevention and treatment of hypertension.

Antihypertensive, cardio- and neuro-protective effects of Tenebrio molitor (Coleoptera: Tenebrionidae) defatted larvae in spontaneously hypertensive rats

In pre-hypertension, moderate control of blood pressure (BP) can be obtained by a nutritional approach. The effects of a diet enriched with defatted larvae of the mealworm Tenebrio molitor (Coleoptera: Tenebrionidae) (TM) endowed with ACE inhibitory activity was studied in both spontaneously hypertensive rats (SHR) and in the age-matched normotensive Wistar Kyoto strain. These were fed for 4 weeks with standard laboratory rodent chow supplemented with or without TM or captopril. In SHR, the TM diet caused a significant reduction in BP, heart rate and coronary perfusion pressure, as well as an increase in red blood cell glutathione/glutathione disulphide ratio. Rat brain slices of SHR were more resistant to oxidative stress and contained lower levels of inflammatory cytokines, while vascular and liver enzyme-activities were not affected. These results suggest that TM can be considered a new functional food that can lower BP in vivo and thus control cardiovascular-associated risk factors such as hypertension.

Is the Brain an Early or Late Component of Essential Hypertension?

The brain's relationship to essential hypertension is primarily understood to be that of an end-organ, damaged late in life by stroke or dementia. Emerging evidence, however, shows that heightened blood pressure (BP) early in life and prior to traditionally defined hypertension, relates to altered brain structure, cerebrovascular function, and cognitive processing. Deficits in cognitive function, cerebral blood flow responsivity, volumes of brain areas, and white matter integrity all relate to increased but prehypertensive levels of BP. Such relationships may be observed as early as childhood. In this review, we consider the basis of these relationships by examining the emergence of putative causative factors for hypertension that would impact or involve brain function/structure, e.g., sympathetic nervous system activation and related endocrine and inflammatory activation. Currently, however, available evidence is not sufficient to fully explain the specific pattern of brain deficits related to heightened BP. Despite this uncertainty, the evidence reviewed suggests the value that early intervention may have, not only for reducing BP, but also for maintaining brain function.