The Renin-Angiotensin System in the Central Nervous System and Its Role in Blood Pressure Regulation

Elevated serum angiotensin ii levels in children and adolescents with anxiety disorders

PURPOSE

Angiotensin II peptide is implicated in oxidative stress, neuropathology, and the serotonergic system. We investigated the serum angiotensin II levels in non-medicated children and adolescents with anxiety disorders.

MATERIALS AND METHODS

Thirty-nine children and adolescents diagnosed with anxiety disorders and thirty-five controls participated in this study to investigate the potential association between anxiety disorders and serum angiotensin II levels. Parents of the participants completed the RCADS-P parent version to assess their children's anxiety and depression levels.

RESULTS

Higher serum angiotensin II levels were found in individuals with anxiety disorders compared to the control group. We found that social phobia, panic disorder, low mood (major depressive disorder), and generalized anxiety disorder subscale scores on the RCADS-P were significantly correlated with angiotensin II levels.

CONCLUSIONS

We found that children and adolescents with anxiety disorders had higher serum angiotensin II levels. The current findings align with previous research on the role of angiotensin II in other mental health conditions. Further research is necessary to elucidate its role in anxiety disorders.

A Bibliometric Analysis of hypertension and anxiety from 2004 to 2022

BACKGROUND

A growing body of clinical evidence points to an association between hypertension and anxiety, but the mechanisms by which the two occur are unclear. This article aims to explore possible common influences and associations between hypertension and anxiety.

METHODS

We searched for publications on hypertension and anxiety from January 01, 2004 to December 31, 2022 in Web of Science and performed bibliometrics using CiteSpace, VOSviewer, Scimago Graphica and Gephi.

RESULTS

A total of 3216 related articles were retrieved from the Web of Science database. After screening, 3051 articles were included. The number of published articles has increased over the past 19 years. The United States has more researches in this area and has strong collaborative relationships with other countries, which gives it some credibility and authority. The words that appear in the burst keywords are gender, age, obesity, depression, panic disorder, pregnancy induced hypertension, coronary heart disease, chronic kidney disease, and pituitary adrenal axi, which are co-related with hypertension and anxiety.

CONCLUSION

There is a link between hypertension and anxiety, and the 2 influence each other, usually in a positive way. Common influences on hypertension and anxiety include age, gender, obesity, depression, panic attacks, pregnancy, coronary heart disease and chronic kidney disease. Recent research hotspots have focused on population aging and comorbidities. Future research hotspots are likely continue to focus on influencing factors, clinical research and prognosis.

Silent Effects of High Salt: Risks Beyond Hypertension and Body's Adaptation to High Salt

Hypertension is a major contributor to heart disease, renal failure, and stroke. High salt is one of the significant risk factors associated with the onset and persistence of hypertension. Experimental and observational studies have confirmed cardiovascular and non-cardiovascular detrimental effects associated with chronic intake of high salt. Because of convenience and present urban lifestyles, consumption of fast food has led to daily salt intake above the recommended level by the World Health Organization. This study provides an understanding of the body regulatory mechanisms that maintain sodium homeostasis under conditions of high salt intake, without health consequences, and how these mechanisms adapt to chronic high salt load, leading to adverse cardiovascular, renal, and non-cardiovascular outcomes. Recent research has identified several mechanisms through which high sodium intake contributes to hypertension. Of them, heightened renin-angiotensin-aldosterone and sympathetic activity associated with impaired pressure diuresis and natriuresis and decreased renal excretory response are reported. Additionally, there is the possibility of endothelial and nitric oxide dysfunction leading to vascular remodeling. These changes raise cardiac output and peripheral vascular resistance. Knowing how these collective mechanisms adapt to chronic intakes of high salt helps develop effective therapeutic policies to fight salt-induced hypertension.

The role of ACE inhibitors and ARBs in preserving cognitive function via hypertension Management: A critical Update

Hypertension poses a significant risk to cognition-related disorders like dementia. As the global population ages, age-related neurological illnesses such as Alzheimer's disease are becoming increasingly prevalent. The primary hypertension treatments, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors, exhibit neuroprotective properties. However, observational studies suggest that they may independently contribute to cognitive decline and dementia. Some of these medications have shown promise in reducing cognitive impairment and amyloid buildup in Alzheimer's models. While direct comparisons between the two drug classes are limited, angiotensin receptor blockers have been associated with less brain shrinkage, lower dementia incidence, and slower cognitive decline compared to angiotensin-converting enzyme inhibitors. Both types of medications can influence cognition by passing the blood-brain barrier, with angiotensin receptor blockers potentially offering superior neuroprotective effects due to their selective blockade of the angiotensin type 1 receptor.

The brain and hypertension: how the brain regulates and suffers from blood pressure

The brain plays several roles in the relationship between blood pressure (BP) and the brain: it acts as the control center for BP regulation, a target organ in hypertension, and a crucial component for cognitive function. This mini-review introduces recent findings on "brain and hypertension" from Hypertension Research and other journals. Activation of the angiotensin II type 1 receptor (AT1R) signaling pathway in the brain causes sympathoexcitation and hypertension. AT1R-associated protein and β-arrestin promote AT1R internalization and suppress AT1R signaling, with brain-specific roles in BP regulation. The brain receives various inputs from the peripheral system, including the heart and kidneys, and controls central sympathetic outflow. The brain mechanism involved in the enhanced cardiac sympathetic afferent reflex and the beneficial effects of renal denervation have been demonstrated. The brain's vulnerability in hypertension includes stroke, with cerebral small vessel disease (SVD) contributing to stroke risk and brain changes. Sex differences and the age of hypertension onset influence these outcomes. High salt intake exacerbates hypertension and stroke risk, with central mechanisms like sympathoexcitation implicated. Hypertension significantly impacts cognitive function, linking to cerebral SVD and cognitive decline. Orthostatic BP regulation abnormalities also emerge as early risk markers for dementia. Improved BP control in hypertensive individuals can significantly reduce the risk of stroke and cognitive decline, as well as cardiovascular disease, enhancing overall brain health and quality of life. Further understanding the brain's role in BP regulation and the pathogenesis of hypertension will facilitate the development of novel hypertension treatments and prevention strategies.

Angiotensin-(1-7) and Central Control of Cardiometabolic Outcomes: Implications for Obesity Hypertension

Hypertension is a leading independent risk factor for the development of cardiovascular disease, the leading cause of death globally. Importantly, the prevalence of hypertension is positively correlated with obesity, with obesity-related hypertension being difficult to treat due to a lack of current guidelines in this population as well as limited efficacy and adverse off-target effects of currently available antihypertensive therapeutics. This highlights the need to better understand the mechanisms linking hypertension with obesity to develop optimal therapeutic approaches. In this regard, the renin-angiotensin system, which is dysregulated in both hypertension and obesity, is a prime therapeutic target. While research and therapies have typically focused on the deleterious angiotensin II axis of the renin-angiotensin system, emerging evidence shows that targeting the protective angiotensin-(1-7) axis also improves cardiovascular and metabolic functions in animal models of obesity hypertension. While the precise mechanisms involved remain under investigation, in addition to peripheral actions, evidence exists to support a role for the central nervous system in the beneficial cardiometabolic effects of angiotensin-(1-7). This review will highlight emerging translational studies exploring the cardiovascular and metabolic regulatory actions of angiotensin-(1-7), with an emphasis on its central actions in brain regions including the brainstem and hypothalamus. An improved understanding of the central mechanisms engaged by angiotensin-(1-7) to regulate cardiovascular and metabolic functions may provide insight into the potential of targeting this hormone as a novel therapeutic approach for obesity-related hypertension.

FABIO: TWAS fine-mapping to prioritize causal genes for binary traits

Transcriptome-wide association studies (TWAS) have emerged as a powerful tool for identifying gene-trait associations by integrating gene expression mapping studies with genome-wide association studies (GWAS). While most existing TWAS approaches focus on marginal analyses through examining one gene at a time, recent developments in TWAS fine-mapping methods enable the joint modeling of multiple genes to refine the identification of potentially causal ones. However, these fine-mapping methods have primarily focused on modeling quantitative traits and examining local genomic regions, leading to potentially suboptimal performance. Here, we present FABIO, a TWAS fine-mapping method specifically designed for binary traits that is capable of modeling all genes jointly on an entire chromosome. FABIO employs a probit model to directly link the genetically regulated expression (GReX) of genes to binary outcomes while taking into account the GReX correlation among all genes residing on a chromosome. As a result, FABIO effectively controls false discoveries while offering substantial power gains over existing TWAS fine-mapping approaches. We performed extensive simulations to evaluate the performance of FABIO and applied it for in-depth analyses of six binary disease traits in the UK Biobank. In the real datasets, FABIO significantly reduced the size of the causal gene sets by 27.9%-36.9% over existing approaches across traits. Leveraging its improved power, FABIO successfully prioritized multiple potentially causal genes associated with the diseases, including GATA3 for asthma, ABCG2 for gout, and SH2B3 for hypertension. Overall, FABIO represents an effective tool for TWAS fine-mapping of disease traits.

From Sea to Lab: Angiotensin I-Converting Enzyme Inhibition by Marine Peptides-Mechanisms and Applications

To reveal potent ACE inhibitors, researchers screen various bioactive peptides from several sources, and more attention has been given to aquatic sources. This review summarizes the recent research achievements on marine peptides with ACE-inhibitory action and application. Marine peptides are considered excellent bioactives due to their large structural diversity and unusual bioactivities. The mechanisms by which these marine peptides inhibit ACE include competitive binding to ACEs' active site, interfering with ACE conformational changes, and avoiding the identification of substrates. The unique 3D attributes of marine peptides confer inhibition advantages toward ACE activity. Because IC50 values of marine peptides' interaction with ACE are low, structure-based research assumes that the interaction between ACE and peptides increased the therapeutic application. Numerous studies on marine peptides focused on the sustainable extraction of ACE-inhibitory peptides produced from several fish, mollusks, algae, and sponges. Meanwhile, their potential applications and medical benefits are worth investigating and considering. Due to these peptides exhibiting antioxidant, antihypertensive, and even antimicrobial properties simultaneously, their therapeutic potential for cardiovascular disease and other illnesses only increases. In addition, as marine peptides show better pharmacological benefits, they have increased absorption rates and low toxicity and could perhaps be modified for better stability and bioefficacy. Biotechnological advances in peptide synthesis and formulation have greatly facilitated the generation of peptide-based ACE inhibitors from marine sources, which subsequently offer new treatment models. This article gives a complete assessment of the present state of knowledge about marine organism peptides as ACE inhibitors. In addition, it emphasizes the relevance of additional investigation into their mechanisms of action, the optimization of manufacturing processes, and assessment in in vivo, preclinical, and clinical settings, underlining the urgency and value of this study. Using marine peptides for ACE inhibition not only broadens the repertory of bioactive compounds but also shows promise for tackling the global health burden caused by cardiovascular diseases.

Acupoint catgut embedding attenuates oxidative stress and cognitive impairment in chronic cerebral ischemia by inhibiting the Ang II/AT1R/NOX axis

Chronic cerebral ischemia (CCI) is a common neurological disorder, characterized by progressive cognitive impairment. Acupoint catgut embedding (ACE) represents a modern acupuncture form that has shown neuroprotective effects; nevertheless, its effects on CCI and the mechanisms remain largely unknown. Here, we aimed to explore the therapeutic action of ACE in CCI-induced cognitive impairment and its mechanisms. The cognitive function of CCI rats was determined using Morris water maze test, and histopathological changes in the brain were assessed through hematoxylin-eosin (HE) staining. To further explore the molecular mechanisms, the expression levels of oxidative stress markers and the Ang II/AT1R/NOX axis-associated molecules in the hippocampus were evaluated using enzyme-linked immunosorbent assay (ELISA), western blotting, and immunohistochemistry. Here, we observed that ACE treatment alleviated cognitive dysfunction and histopathological injury in CCI rats. Intriguingly, candesartan (an AT1R blocker) enhanced the beneficial effects of ACE on ameliorating cognitive impairment in CCI rats. Mechanistically, ACE treatment blocked the Ang II/AT1R/NOX pathway and subsequently suppressed oxidative stress, thus mitigating cognitive impairment in CCI. Our findings first reveal that ACE treatment could suppress cognitive impairment in CCI, which might be partly due to the suppression of Ang II/AT1R/NOX axis.

Afferent Renal Denervation Attenuates Sympathetic Overactivation From the Paraventricular Nucleus in Spontaneously Hypertensive Rats

BACKGROUND

The effectiveness of renal denervation (RDN) in reducing blood pressure and systemic sympathetic activity in hypertensive patients has been established. However, the underlying central mechanism remains unknown. This study aimed to investigate the role of RDN in regulating cardiovascular function via the central renin-angiotensin system (RAS) pathway.

METHODS

Ten-week-old spontaneously hypertensive rats (SHR) were subjected to selective afferent renal denervation (ADN) using capsaicin solution. We hypothesized that ADN would effectively reduce blood pressure and rebalance the RAS component of the paraventricular nucleus (PVN) in SHR.

RESULTS

The experimental results show that the ADN group exhibited significantly lower blood pressure, reduced systemic sympathetic activity, decreased chronic neuronal activation marker C-FOS expression in the PVN, and improved arterial baroreflex function, compared with the Sham group. Furthermore, ACE and AT1 protein expression was reduced while ACE2 and MAS protein expression was increased in the PVN of SHR after ADN.

CONCLUSIONS

These findings suggest that RDN may exert these beneficial effects through modulating the central RAS pathway.

Neural Circuits Underlying Reciprocal Cardiometabolic Crosstalk: 2023 Arthur C. Corcoran Memorial Lecture

The interplay of various body systems, encompassing those that govern cardiovascular and metabolic functions, has evolved alongside the development of multicellular organisms. This evolutionary process is essential for the coordination and maintenance of homeostasis and overall health by facilitating the adaptation of the organism to internal and external cues. Disruption of these complex interactions contributes to the development and progression of pathologies that involve multiple organs. Obesity-associated cardiovascular risks, such as hypertension, highlight the significant influence that metabolic processes exert on the cardiovascular system. This cardiometabolic communication is reciprocal, as indicated by substantial evidence pointing to the ability of the cardiovascular system to affect metabolic processes, with pathophysiological implications in disease conditions. In this review, I outline the bidirectional nature of the cardiometabolic interaction, with special emphasis on the impact that metabolic organs have on the cardiovascular system. I also discuss the contribution of the neural circuits and autonomic nervous system in mediating the crosstalk between cardiovascular and metabolic functions in health and disease, along with the molecular mechanisms involved.

Role of Inflammation in the Development of COVID-19 to Parkinson's Disease

Background

The coronavirus disease 2019 (COVID-19) can lead to neurological symptoms such as headaches, confusion, seizures, hearing loss, and loss of smell. The link between COVID-19 and Parkinson's disease (PD) is being investigated, but more research is needed for a definitive connection.

Methods

Datasets GSE22491 and GSE164805 were selected to screen differentially expressed gene (DEG), and immune infiltration and gene set enrichment analysis (GSEA) of the DEG were performed. WGCNA analyzed the DEG and selected the intersection genes. Potential biological functions and signaling pathways were determined, and diagnostic genes were further screened using gene expression and receiver operating characteristic (ROC) curves. Screening and molecular docking of ibuprofen as a therapeutic target. The effectiveness of ibuprofen was verified by constructing a PD model in vitro, and constructing "COVID19-PD" signaling pathway, and exploring the role of angiotensin-converting enzyme 2 (ACE2) in PD.

Results

A total of 13 DEG were screened from the GSE36980 and GSE5281 datasets. Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that the DEG were mainly associated with the hypoxia-inducible factor (HIF-1), epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, etc. After analysis, it is found that ibuprofen alleviates PD symptoms by inhibiting the expression of nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Based on signal pathway construction, the importance of ACE2 in COVID-19-induced PD has been identified. ACE2 is found to have widespread distribution in the brain. In the 1-methyl-4-phenyl-1,2,3,6-te-trahydropyridine (MPTP)-induced ACE2-null PD mice model, more severe motor and non-motor symptoms, increased NF-κB p65 and α-synuclein (α-syn) expression with significant aggregation, decreased tyrosine hydroxylase (TH), severe neuronal loss, and neurodegenerative disorders.

Conclusion

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection increases the risk of PD through an inflammatory environment and downregulation of ACE2, providing evidence for the molecular mechanism and targeted therapy associated with COVID-19 and PD.

Modulatory Effects of the Kuwanon-Rich Fraction from Mulberry Root Bark on the Renin-Angiotensin System

In this study, we investigated the anti-hypertensive properties of mulberry products by modulating the renin-angiotensin system (RAS). Comparative analysis showed that the ethyl acetate fractions, particularly from the Cheongil and Daeshim cultivars, contained the highest levels of polyphenols and flavonoids, with concentrations reaching 110 mg gallic acid equivalent (GE)/g and 471 mg catechin equivalent (CE)/g of extract, respectively. The ethyl acetate fraction showed superior angiotensin-converting enzyme (ACE) inhibitory activity, mainly because of the presence of the prenylated flavonoids kuwanon G and H. UPLC/Q-TOF-MS analysis identified kuwanon G and H as the primary active components, which significantly contributed to the pharmacological efficacy of the extract. In vivo testing of mice fed a high-salt diet showed that the ethyl acetate fraction substantially reduced the heart weight and lowered the serum renin and angiotensinogen levels by 34% and 25%, respectively, highlighting its potential to modulate the RAS. These results suggested that the ethyl acetate fraction of mulberry root bark is a promising candidate for the development of natural ACE inhibitors. This finding has significant implications for the management of hypertension through RAS regulation and the promotion of cardiovascular health in the functional food industry.

Anti-Diabetic Potentials of Lactobacillus Strains by Modulating Gut Microbiota Structure and β-Cells Regeneration in the Pancreatic Islets of Alloxan-Induced Diabetic Rats

Diabetes mellitus, a most common endocrine disorder of glucose metabolism, has become a global epidemic and poses a serious public health threat with an increased socio-economic burden. Escalating incidence of diabetes is correlated with changes in lifestyle and food habits that cause gut microbiome dysbiosis and β-cells damage, which can be addressed with dietary interventions containing probiotics. Hence, the search for probiotics of human origin with anti-diabetic, anti-AGE, and anti-ACE potentials has gained renewed interest for the effective management of diabetes and its associated complications. The present study used an alloxan (AXN)-induced diabetic rat model to investigate the effects of potential probiotic Lacticaseibacillus casei MKU1, Lactiplantibacillus pentosus MKU3, and Lactiplantibacillus plantarum MKU7 administration individually on physiochemical parameters related to diabetic pathogenesis. Experimental animals were randomly allotted into six groups viz. NCG (control), DCG (AXN), DGM (metformin), DGP1 (MKU1), DGP2 (MKU3), and DGP3 (MKU7), and biochemical data like serum glucose, insulin, AngII, ACE, HbA1c, and TNF-α levels were measured until 90 days. Our results suggest that oral administration with MKU1, MKU3, or MKU7 significantly improved serum insulin levels, glycemic control, glucose tolerance, and body weight. Additionally, β-cell mass was increased by preserving islet integrity in Lactobacillus-treated diabetic rats, whereas TNF-α (~40%), AngII (~30%), and ACE levels (~50%) were strongly inhibited and enhanced sIgA production (5.8 folds) abundantly. Furthermore, Lactobacillus administration positively influenced the gut microbiome with a significant increase in the abundance of Lactobacillus species and the beneficial Bacteroides uniformis and Bacteroides fragilis, while decreased the pathogenic Proteus vulgaris and Parabacteroides distasonis. Among the probiotic treatment groups, L. pentosus MKU3 performed greatly in almost all parameters, indicating its potential use for alleviating diabetes-associated complications.

Potential molecular pathways of angiotensin receptor blockers in the brain toward cognitive improvement in dementia

The alarming rise of cognitive impairment and memory decline and limited effective solutions present a worldwide concern for dementia patients. The multivariant role of the renin-angiotensin system (RAS) in the brain offers strong evidence of a role for angiotensin receptor blockers (ARBs) in the management of memory impairment by modifying glutamate excitotoxicity, downregulating inflammatory cytokines such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)α, inhibiting kynurenine aminotransferase (KAT)-II, nucleotide-binding domain, leucine-rich-containing family and pyrin-domain-containing-3 (NLRP3) inflammasomes, boosting cholinergic activity, activating peroxisome proliferator-activated receptor (PPAR)-γ, countering cyclooxygenase (COX) and mitigating the hypoxic condition. The present work focuses on the intricate molecular mechanisms involved in brain-RAS, highlighting the role of ARBs, connecting links between evidence-based unexplored pathways and investigating probable biomarkers involved in dementia through supported preclinical and clinical literature.

Insights Into the Role of Angiotensin-II AT1 Receptor-Dependent β-Arrestin Signaling in Cardiovascular Disease

β-arrestins are a family of intracellular signaling proteins that play a key role in regulating the activity of G protein-coupled receptors. The angiotensin-II type 1 receptor is an important G protein-coupled receptor involved in the regulation of cardiovascular function and has been implicated in the progression of cardiovascular diseases. In addition to canonical G protein signaling, G protein-coupled receptors including the angiotensin-II type 1 receptor can signal via β-arrestin. Dysregulation of β-arrestin signaling has been linked to several cardiovascular diseases including hypertension, atherosclerosis, and heart failure. Understanding the role of β-arrestins in these conditions is critical to provide new therapeutic targets for the treatment of cardiovascular disease. In this review, we will discuss the beneficial and maladaptive physiological outcomes of angiotensin-II type 1 receptor-dependent β-arrestin activation in different cardiovascular diseases.

Role of Inflammatory Processes in the Brain-Body Relationship Underlying Hypertension

PURPOSE OF REVIEW

Essential hypertension is a huge health problem that significantly impacts worldwide population in terms of morbidity and mortality. Idiopathic in its nature, elevated blood pressure results from a complex interaction between polygenic components and environmental and lifestyle factors. The constant growth in the burden of hypertension is at odds with expectations, considering the availability of therapeutic strategies. Hence, there is an endless need to further investigate the complexity of factors contributing to blood pressure elevation.

RECENT FINDINGS

Recent data indicate that bidirectional interactions between the nervous system and the immune system alter inflammation in the brain and periphery, contributing to chronic hypertension. These findings indicate that the nervous system is both a direct driver of hypertension and also a target of feedback that often elevates blood pressure further. Similarly, the immune system is both target and driver of the blood pressure increases. The contributions of the feedback loops among these systems appear to play an important role in hypertension. Together, recent mechanistic studies strongly suggest that the interactions among the brain, immune system, and inflammation affect the participation of each system in the pathogenesis of hypertension, and thus, all of these systems must be considered in concert to gain a full appreciation of the development and potential treatments of hypertension.

Genetic Ablation of Prorenin Receptor in the Rostral Ventrolateral Medulla Influences Blood Pressure and Hydromineral Balance in Deoxycorticosterone-Salt Hypertension

Non-enzymatic activation of renin via its interaction with prorenin receptor (PRR) has been proposed as a key mechanism of local renin-angiotensin system (RAS) activation. The presence of renin and angiotensinogen has been reported in the rostral ventrolateral medulla (RVLM). Overactivation of bulbospinal neurons in the RVLM is linked to hypertension (HTN). Previous studies have shown that the brain RAS plays a role in the pathogenesis of the deoxycorticosterone (DOCA)-salt HTN model. Thus, we hypothesized that PRR in the RVLM is involved in the local activation of the RAS, facilitating the development of DOCA-salt HTN. Selective PRR ablation targeting the RVLM (PRRRVLM-Null mice) resulted in an unexpected sex-dependent and biphasic phenotype in DOCA-salt HTN. That is, PRRRVLM-Null females (but not males) exhibited a significant delay in achieving maximal pressor responses during the initial stage of DOCA-salt HTN. Female PRRRVLM-Null subsequently showed exacerbated DOCA-salt-induced pressor responses during the "maintenance" phase with a maximal peak at 13 d on DOCA-salt. This exacerbated response was associated with an increased sympathetic drive to the resistance arterioles and the kidney, exacerbated fluid and sodium intake and output in response to DOCA-salt, and induced mobilization of fluids from the intracellular to extracellular space concomitant with elevated vasopressin. Ablation of PRR suppressed genes involved in RAS activation and catecholamine synthesis in the RVLM but also induced expression of genes involved in inflammatory responses. This study illustrates complex and sex-dependent roles of PRR in the neural control of BP and hydromineral balance through autonomic and neuroendocrine systems. Graphical abstract.

Cardiomodulatory and Antioxidative Potentials of Almond-Citrus Peel Fortified Shortbread in High Fat Diet/L-NAME-Induced Hyperlipidemic-Hypertensive Rats

In folk medicine, the almond nut (Terminalia catappa) and orange peel (Citrus sinensis) are cost-effective sources of nutraceutical utilized in the treatment of degenerative diseases. Hyperlipidemia and hypertension are two pathological conditions implicated in cardiovascular disorders. This study sought to evaluate the cardiomodulatory effect of almond-citrus peel fortified shortbread in hyperlipidemic-hypertensive rats induced by high fat diet and Nω-nitro-l-arginine methyl ester. The experimental animals were divided into eight groups. The experimental rats were fed with shortbread supplemented with almond and citrus peel at varying inclusions of 0.2% citrus, 50% almond, and almond (50%)- citrus (0.2%) for 21 days. The mean arterial blood pressure (MABP), systolic blood pressure (SBP), and lipid profile of the experimental rats were measured. Thereafter, the activities of angiotensin-1-converting enzyme (ACE), arginase, malondialdehyde (MDA), phosphodiesterase-5, nitric oxide (NO), and antioxidant indices were evaluated. The result showed significant elevation in SBP, MABP, blood cholesterol, triglyceride, ACE, arginase, activities, and MDA levels in the heart tissue of the untreated rats. In contrast, the antioxidant status and NO level were significantly decreased in the untreated groups. Remarkably, the treatment with almond-citrus peel fortified shortbread and the individual effect of almond (50%) and citrus peel (0.2%) all reversed these trends in the hyperlipidemic-hypertensive rats. Intriguingly, the blend of almond (50%)-citrus peel (0.2%) fortified shortbread showed the best antioxidative and cardioprotective effect. The results suggest that almond and citrus peel offer potentials as therapeutic agent in the prevention and management of hyperlipidemia and hypertension.

Effects and mechanisms of extremely cold environment on body response after trauma

With the outbreak of the Ukrainian crisis, extremely cold environment warfare has once again become the focus of international attention. People exposed to extremely cold environments may suffer from cold damage, further aggravate trauma, trigger high disability and mortality rates, and even cause serious sequelae. To declare the effects and mechanisms of the extremely cold environment on the body after trauma, this paper reviews, firstly, physiological reaction of human body in an extremely cold environment. Then, the post-traumatic body response in an extremely cold environment was introduced, and finally, the sequelae of trauma in extremely cold environment was further summarized in the paper. The results indicated that extremely cold environment can cause a series of damage to the body, especially the body after trauma. The extremely cold factor is a double-edged sword, showing a favorable and unfavorable side in different aspects. Moreover, in addition to the trauma suffered by the body, the subsequent sequelae such as cognitive dysfunction, anxiety, depression and even post-traumatic stress disorder may also be induced. The paper summarizes the human body's physiological response in an extremely cold environment, and declares the effects and mechanisms of the extremely cold environment on the body after trauma, which may provide a theoretical basis for effectively improving the level of combat trauma treatment in extremely cold regions.

Activation of aryl hydrocarbon receptor (AhR) in Alzheimer's disease: role of tryptophan metabolites generated by gut host-microbiota

Gut microbiota in interaction with intestinal host tissues influences many brain functions and microbial dysbiosis has been linked with brain disorders, such as neuropsychiatric conditions and Alzheimer's disease (AD). L-tryptophan metabolites and short-chained fatty acids (SCFA) are major messengers in the microbiota-brain axis. Aryl hydrocarbon receptors (AhR) are main targets of tryptophan metabolites in brain microvessels which possess an enriched expression of AhR protein. The Ah receptor is an evolutionarily conserved, ligand-activated transcription factor which is not only a sensor of xenobiotic toxins but also a pleiotropic regulator of both developmental processes and age-related tissue degeneration. Major microbiota-produced tryptophan metabolites involve indole derivatives, e.g., indole 3-pyruvic acid, indole 3-acetaldehyde, and indoxyl sulfate, whereas indoleamine and tryptophan 2,3-dioxygenases (IDO/TDO) of intestine host cells activate the kynurenine (KYN) pathway generating KYN metabolites, many of which are activators of AhR signaling. Chronic kidney disease (CKD) increases the serum level of indoxyl sulfate which promotes AD pathogenesis, e.g., it disrupts integrity of blood-brain barrier (BBB) and impairs cognitive functions. Activation of AhR signaling disturbs vascular homeostasis in brain; (i) it controls blood flow via the renin-angiotensin system, (ii) it inactivates endothelial nitric oxide synthase (eNOS), thus impairing NO production and vasodilatation, and (iii) it induces oxidative stress, stimulates inflammation, promotes cellular senescence, and enhances calcification of vascular walls. All these alterations are evident in cerebral amyloid angiopathy (CAA) in AD pathology. Moreover, AhR signaling can disturb circadian regulation and probably affect glymphatic flow. It seems plausible that dysbiosis of gut microbiota impairs the integrity of BBB via the activation of AhR signaling and thus aggravates AD pathology. KEY MESSAGES: Dysbiosis of gut microbiota is associated with dementia and Alzheimer's disease. Tryptophan metabolites are major messengers from the gut host-microbiota to brain. Tryptophan metabolites activate aryl hydrocarbon receptor (AhR) signaling in brain. The expression of AhR protein is enriched in brain microvessels and blood-brain barrier. Tryptophan metabolites disturb brain vascular integrity via AhR signaling. Dysbiosis of gut microbiota promotes inflammation and AD pathology via AhR signaling.

Sodium Intake and Disease: Another Relationship to Consider

Sodium (Na+) is crucial for numerous homeostatic processes in the body and, consequentially, its levels are tightly regulated by multiple organ systems. Sodium is acquired from the diet, commonly in the form of NaCl (table salt), and substances that contain sodium taste salty and are innately palatable at concentrations that are advantageous to physiological homeostasis. The importance of sodium homeostasis is reflected by sodium appetite, an "all-hands-on-deck" response involving the brain, multiple peripheral organ systems, and endocrine factors, to increase sodium intake and replenish sodium levels in times of depletion. Visceral sensory information and endocrine signals are integrated by the brain to regulate sodium intake. Dysregulation of the systems involved can lead to sodium overconsumption, which numerous studies have considered causal for the development of diseases, such as hypertension. The purpose here is to consider the inverse-how disease impacts sodium intake, with a focus on stress-related and cardiometabolic diseases. Our proposition is that such diseases contribute to an increase in sodium intake, potentially eliciting a vicious cycle toward disease exacerbation. First, we describe the mechanism(s) that regulate each of these processes independently. Then, we highlight the points of overlap and integration of these processes. We propose that the analogous neural circuitry involved in regulating sodium intake and blood pressure, at least in part, underlies the reciprocal relationship between neural control of these functions. Finally, we conclude with a discussion on how stress-related and cardiometabolic diseases influence these circuitries to alter the consumption of sodium.

Age-related reduction in brain ACE-2 is not exacerbated by Alzheimer's disease pathology in mouse models of Alzheimer's disease

An imbalance in the circulatory and organ-specific renin-angiotensin system (RAS) pathways is associated with age-related dysfunction and disease including cardiovascular burden and more recently Alzheimer's disease (AD). It is currently unclear whether an age-associated imbalance in components of the RAS within the brain precedes the onset of AD or whether a RAS imbalance is associated with the onset of disease pathology and cognitive decline. Angiotensin-converting enzyme-1 (ACE-1) and -2 (ACE-2) protein (ELISA) and enzyme activity (FRET assay), markers of the classical and counter-regulatory RAS axis respectively, and Ang-II and Ang-(1-7) peptide levels (ELISA), were measured in the left cortex across four transgenic AD mouse models of amyloid pathology (5xFAD - 2, 6, and 12 months of age; Apd9 - 3-4, 12, and 18 months of age; Tg2576 - 3-4 and 24 months of age; and PDAPP - 3-4, 7, 11, 15, and 18 months of age) and littermate wild-type (WT) controls. ACE-1 level, and enzyme activity, was unaltered in relation to age in WT mice and across all four models. In contrast, ACE-2 level and enzyme activity, was reduced and Ang-II increased with ageing in both WT animals and disease models. The changes in ACE-2 and Ang-II in AD models mirrored WT mice, except for the 5xFAD model, when the reduction in ACE-2 (and elevated Ang-II) was observed at a younger age. These data indicate an age-related dysregulation of brain RAS is likely to be driven by a reduction in ACE-2. The reduction in ACE-2 occurs at a young age, coinciding with early pathological changes and the initial deposition of Aβ, and preceding neuronal loss and cognitive decline, in the transgenic AD models. However, the age-related loss was mirrored in WT mice suggesting that the change was independent of pathological Aβ deposition.

Chemotherapy induces ACE2 expression in breast cancer via the ROS-AKT-HIF-1α signaling pathway: a potential prognostic marker for breast cancer patients receiving chemotherapy

Background

Angiotensin-converting enzyme 2 (ACE2) is a key enzyme of the renin-angiotensin system and a well-known functional receptor for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells. The COVID-19 pandemic has brought ACE2 into the spotlight, and ACE2 expression in tumors and its relationship with SARS-COV-2 infection and prognosis of cancer patients have received extensive attention. However, the association between ACE2 expression and tumor therapy and prognosis, especially in breast cancer, remains ambiguous and requires further investigation. We have previously reported that ACE2 is elevated in drug-resistant breast cancer cells, but the exact function of ACE2 in drug resistance and progression of this malignant disease has not been explored.

Methods

The expression of ACE2 and HIF-1α in parental and drug-resistant breast cancer cells under normoxic and hypoxic conditions was analyzed by Western blot and qRT-PCR methods. The protein levels of ACE2 in plasma samples from breast cancer patients were examined by ELISA. The relationship between ACE2 expression and breast cancer treatment and prognosis was analyzed using clinical specimens and public databases. The reactive oxygen species (ROS) levels in breast cancer cells were measured by using a fluorescent probe. Small interfering RNAs (siRNAs) or lentivirus-mediated shRNA was used to silence ACE2 and HIF-1α expression in cellular models. The effect of ACE2 knockdown on drug resistance in breast cancer was determined by Cell Counting Kit 8 (CCK-8)-based assay, colony formation assay, apoptosis and EdU assay.

Results

ACE2 expression is relatively low in breast cancer cells, but increases rapidly and specifically after exposure to anticancer drugs, and remains high after resistance is acquired. Mechanistically, chemotherapeutic agents increase ACE2 expression in breast cancer cells by inducing intracellular ROS production, and increased ROS levels enhance AKT phosphorylation and subsequently increase HIF-1α expression, which in turn upregulates ACE2 expression. Although ACE2 levels in plasma and cancer tissues are lower in breast cancer patients compared with healthy controls, elevated ACE2 in patients after chemotherapy is a predictor of poor treatment response and an unfavorable prognostic factor for survival in breast cancer patients.

Conclusion

ACE2 is a gene in breast cancer cells that responds rapidly to chemotherapeutic agents through the ROS-AKT-HIF-1α axis. Elevated ACE2 modulates the sensitivity of breast cancer cells to anticancer drugs by optimizing the balance of intracellular ROS. Moreover, increased ACE2 is not only a predictor of poor response to chemotherapy, but is also associated with a worse prognosis in breast cancer patients. Thus, our findings provide novel insights into the spatiotemporal differences in the function of ACE2 in the initiation and progression of breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03716-w.

Correlation between serum angiotensin-converting enzyme (ACE) levels and intervertebral disc degeneration

Studies have shown that the renin-angiotensin system (RAS) might play an essential role in intervertebral disc degeneration (IDD). The study aimed to investigate the relationship between serum angiotensin-converting enzyme (ACE) concentration and IDD and its predictive value for severe disc degeneration. 245 patients who came to our hospital for low back pain were recruited, and blood samples were collected for routine examination. Descriptive data and demographic parameters were collected. The cumulative grade 1 was calculated by summing up the Pfirrmann grade of all lumbar discs. ACE concentration grouping was determined via tertile split. Correlation analysis and multivariable linear regression analysis were performed to determine the relationship between ACE and IDD. The receiver's degree of disc degeneration (ROC) curve determined the ACE's predictive value. Results indicated that there was no significant difference in demographic parameters among groups. Correlation analysis and multivariate linear analysis showed that ACE was an independent risk factor for IDD. The cumulative grade 1 increased significantly with the increase in ACE concentration, which was consistent with the correlation analysis. Average Pfirrmann grade < 4 indicates mild to moderate degeneration, and grade ≥ 4 indicates severe degeneration in terms of an individual disc. From L1/2 to L5/S1, the mean plasma ACE concentration was significantly higher in the severe degeneration group than in the mild to moderate degeneration group. According to the ROC curve, the cut-off value of ACE levels was 22.5. patients with ACE > 22.5 had severe degeneration. The sensitivity and specificity were 0.762 and 0.521, respectively.

ARRB2 (β-Arrestin-2) Deficiency Alters Fluid Homeostasis and Blood Pressure Regulation

BACKGROUND

GPCRs (G protein-coupled receptors) are implicated in blood pressure (BP) and fluid intake regulation. There is a developing concept that these effects are mediated by both canonical G protein signaling and noncanonical β-arrestin mediated signaling, but the contributions of each remain largely unexplored. Here, we hypothesized that β-arrestin contributes to fluid homeostasis and blood pressure (BP) regulation in deoxycorticosterone acetate (DOCA) salt hypertension, a prototypical model of salt-sensitive hypertension.

METHODS

Global β-arrestin1 (Arrb1) and β-arrestin2 (Arrb2) knockout mice were employed to evaluate drinking behavior, and BP was evaluated in Arrb2-knockout mice. Age- and sex-matched C57BL/6 mice served as controls. We measured intake of water and different sodium chloride solutions and BP employing a 2-bottle choice paradigm with and without DOCA.

RESULTS

Without DOCA (baseline), Arrb2-knockout mice exhibited a significant elevation in saline intake with no change in water intake. With DOCA treatment, Arrb2-knockout mice exhibited a significant increase in both saline and water intake. Although Arrb2-knockout mice exhibited hypernatremia at baseline conditions, we did not find significant changes in total body sodium stores or sodium palatability. In a separate cohort, BP was measured via telemetry in Arrb2-knockout and C57BL/6 mice with and without DOCA. Arrb2-knockout did not exhibit significant differences in BP before DOCA treatment when provided water alone, or when provided a choice of water and saline. However, Arrb2-knockout exhibited an increased pressor response to DOCA-salt.

CONCLUSIONS

These findings suggest that in salt-sensitive hypertension, ARRB2, but not ARRB1 (β-arrestin 1), might counterbalance the canonical signaling of GPCRs.

Renin-a in the Subfornical Organ Plays a Critical Role in the Maintenance of Salt-Sensitive Hypertension

The brain renin-angiotensin system plays important roles in blood pressure and cardiovascular regulation. There are two isoforms of prorenin in the brain: the classic secreted form (prorenin/sREN) encoded by renin-a, and an intracellular form (icREN) encoded by renin-b. Emerging evidence indicates the importance of renin-b in cardiovascular and metabolic regulation. However, the role of endogenous brain prorenin in the development of salt-sensitive hypertension remains undefined. In this study, we test the hypothesis that renin-a produced locally in the brain contributes to the pathogenesis of hypertension. Using RNAscope, we report for the first time that renin mRNA is expressed in several regions of the brain, including the subfornical organ (SFO), the paraventricular nucleus of the hypothalamus (PVN), and the brainstem, where it is found in glutamatergic, GABAergic, cholinergic, and tyrosine hydroxylase-positive neurons. Notably, we found that renin mRNA was significantly elevated in the SFO and PVN in a mouse model of DOCA-salt–induced hypertension. To examine the functional importance of renin-a in the SFO, we selectively ablated renin-a in the SFO in renin-a–floxed mice using a Cre-lox strategy. Importantly, renin-a ablation in the SFO attenuated the maintenance of DOCA-salt–induced hypertension and improved autonomic function without affecting fluid or sodium intake. Molecularly, ablation of renin-a prevented the DOCA-salt–induced elevation in NADPH oxidase 2 (NOX2) in the SFO without affecting NOX4 or angiotensin II type 1 and 2 receptors. Collectively, our findings demonstrate that endogenous renin-a within the SFO is important for the pathogenesis of salt-sensitive hypertension.

Bovine Bone Gelatin-Derived Peptides: Food Processing Characteristics and Evaluation of Antihypertensive and Antihyperlipidemic Activities

This study aimed to evaluate the food processing properties of bovine bone gelatin-derived peptides (BGPs) and their effects and mechanisms on hypertension and hypertension complications in spontaneously hypertensive rats (SHRs). BGPs had good acid, high temperature, and NaCl resistance abilities in vitro. Additionally, Maillard reaction of BGPs with low-dose reducing sugar (≤15%) exhibited a free radical scavenging effect. BGPs significantly reduced the blood pressure, triglyceride levels, and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in SHRs through downregulated angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II type 1 receptor (AT1R) levels and the upregulated Ang II type 2 receptor (AT2R) level. In brief, BGP could alleviate hypertension and dyslipidemia in SHRs by inhibiting ACE/Ang II/AT1R and activating the Ang II/AT2R signaling pathway. Our study suggests that BGP has good food processing properties and could be a potential nutraceutical for antihypertensive and antihyperlipidemic issues.

Antihypertensive drugs and brain function: mechanisms underlying therapeutically beneficial and harmful neuropsychiatric effects

A bidirectional relationship exists between hypertension and psychiatric disorders, including unipolar and bipolar depression, anxiety, post-traumatic stress disorder (PTSD), psychosis, schizophrenia, mania, and dementia/cognitive decline. Repurposing of antihypertensive drugs to treat mental disorders is thus being explored. A systematic knowledge of the mechanisms of action and clinical consequences of the use of antihypertensive agents on neuropsychiatric functions has not been achieved yet. In this article, we review the putative role of antihypertensive agents in psychiatric disorders, discuss the targets and mechanisms of action, and examine how and to what extent specific drug classes/molecules may trigger, worsen, or mitigate psychiatric symptoms. In addition, we review pharmacokinetics (brain penetration of drugs) and pharmacogenetics data that add important information to assess risks and benefits of antihypertensive drugs in neuropsychiatric settings. The scientific literature shows robust evidence of a positive effect of α1 blockers on PTSD symptoms, nightmares and sleep quality, α2 agonists on core symptoms, executive function and quality of life in Attention-Deficit/Hyperactivity Disorder, PTSD, Tourette's syndrome, and β blockers on anxiety, aggression, working memory, and social communication. Renin-angiotensin system modulators exert protective effects on cognition, depression, and anxiety, and the loop diuretic bumetanide reduced the core symptoms of autism in a subset of patients. There is no evidence of clear benefits of calcium channel blockers in mood disorders in the scientific literature. These findings are mainly from preclinical studies; clinical data are still insufficient or of anecdotal nature, and seldom systematic. The information herewith provided can support a better therapeutic approach to hypertension, tailored to patients with, or with high susceptibility to, psychiatric illness. It may prompt clinical studies exploring the potential benefit of antihypertensive drugs in selected patients with neuropsychiatric comorbidities that include outcomes of neuropsychiatric interest and specifically assess undesirable effects or interactions.

Microanalysis of Brain Angiotensin Peptides Using Ultrasensitive Capillary Electrophoresis Trapped Ion Mobility Mass Spectrometry

While the role of the renin-angiotensin system (RAS) in peripheral circulation is well characterized, we still lack an in-depth understanding of its role within the brain. This knowledge gap is sustained by lacking technologies for trace-level angiotensin detection throughout tissues, such as the brain. To provide a bridging solution, we enhanced capillary electrophoresis (CE) nanoflow electrospray ionization (ESI) with large-volume sample stacking and employed trapped ion mobility time-of-flight (timsTOF) tandem HRMS detection. A dynamic pH junction helped stack approximately 10 times more of the sample than optimal using the field-amplified reference. In conjunction, the efficiency of ion generation was maximized by a cone-jet nanospray on a low sheath-flow tapered-tip nano-electrospray emitter. The platform provided additional peptide-dependent information, the collision cross section, to filter chemical noise and improve sequence identification and detection limits. The lower limit of detection reached sub-picomolar or ∼30 zmol (∼18,000 copies) level. All nine targeted angiotensin peptides in mouse tissue samples were detectable and quantifiable from the paraventricular nucleus (PVN) of the hypothalamus even after removal of circulatory blood components (perfusion). We anticipate CE-ESI with timsTOF HRMS to be broadly applicable for the ultrasensitive detection of brain peptidomes in pursuit of a better understanding of the brain.

Involvement of the Renin-Angiotensin System in Stress: State of the Art and Research Perspectives

BACKGROUND

Along with other canonical systems, the renin-angiotensin system (RAS) has shown important roles in stress. This system is a complex regulatory proteolytic cascade composed of various enzymes, peptides, and receptors. Besides the classical (ACE/Ang II/AT1 receptor) and the counter-regulatory (ACE2/Ang-(1-7)/Mas receptor) RAS axes, evidence indicates that nonclassical components, including Ang III, Ang IV, AT₂ and AT₄, can also be involved in stress.

OBJECTIVE AND METHODS

This comprehensive review summarizes the current knowledge on the participation of RAS components in different adverse environmental stimuli stressors, including air jet stress, cage switch stress, restraint stress, chronic unpredictable stress, neonatal isolation stress, and post-traumatic stress disorder.

RESULTS AND CONCLUSION

In general, activation of the classical RAS axis potentiates stress-related cardiovascular, endocrine, and behavioral responses, while the stimulation of the counter-regulatory axis attenuates these effects. Pharmacological modulation in both axes is optimistic, offering promising perspectives for stress-related disorders treatment. In this regard, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are potential candidates already available since they block the classical axis, activate the counter-regulatory axis, and are safe and efficient drugs.

The Pathobiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: The Case for Neuroglial Failure

Although myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has a specific and distinctive profile of clinical features, the disease remains an enigma because causal explanation of the pathobiological matrix is lacking. Several potential disease mechanisms have been identified, including immune abnormalities, inflammatory activation, mitochondrial alterations, endothelial and muscular disturbances, cardiovascular anomalies, and dysfunction of the peripheral and central nervous systems. Yet, it remains unclear whether and how these pathways may be related and orchestrated. Here we explore the hypothesis that a common denominator of the pathobiological processes in ME/CFS may be central nervous system dysfunction due to impaired or pathologically reactive neuroglia (astrocytes, microglia and oligodendrocytes). We will test this hypothesis by reviewing, in reference to the current literature, the two most salient and widely accepted features of ME/CFS, and by investigating how these might be linked to dysfunctional neuroglia. From this review we conclude that the multifaceted pathobiology of ME/CFS may be attributable in a unifying manner to neuroglial dysfunction. Because the two key features - post exertional malaise and decreased cerebral blood flow - are also recognized in a subset of patients with post-acute sequelae COVID, we suggest that our findings may also be pertinent to this entity.

The Pathophysiology of Long COVID throughout the Renin-Angiotensin System

COVID-19 has expanded across the world since its discovery in Wuhan (China) and has had a significant impact on people's lives and health. Long COVID is a term coined by the World Health Organization (WHO) to describe a variety of persistent symptoms after acute SARS-CoV-2 infection. Long COVID has been demonstrated to affect various SARS-CoV-2-infected persons, independently of the acute disease severity. The symptoms of long COVID, like acute COVID-19, consist in the set of damage to various organs and systems such as the respiratory, cardiovascular, neurological, endocrine, urinary, and immune systems. Fatigue, dyspnea, cardiac abnormalities, cognitive and attention impairments, sleep disturbances, post-traumatic stress disorder, muscle pain, concentration problems, and headache were all reported as symptoms of long COVID. At the molecular level, the renin-angiotensin system (RAS) is heavily involved in the pathogenesis of this illness, much as it is in the acute phase of the viral infection. In this review, we summarize the impact of long COVID on several organs and tissues, with a special focus on the significance of the RAS in the disease pathogenesis. Long COVID risk factors and potential therapy approaches are also explored.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers and risk of depression among older people with hypertension

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), commonly used antihypertensive drugs, may have a protective effect against depression in older individuals, but evidence in humans is limited.

AIMS

We evaluated the risk of depression, among older individuals with hypertension, comparing ACE or ARB initiators to thiazide(-like) diuretic initiators. Thiazide(-like) diuretics were used as control because these drugs are not associated with mood disorders.

METHODS

We used a propensity score-matched new user cohort design with routinely collected data from general practices in England from the Clinical Practice Research Datalink database. We matched 12,938 pairs of new users of ACEIs/ARBs and thiazide(-like) diuretics with hypertension (mean age 67.6 years; 54.7% women). Follow-up time started on the date of drug initiation and ended on the date of treatment discontinuation plus 30 days, or switch to a comparator, occurrence of a study event, death, date of patient's transfer out of practice, or end of the study period. The primary outcome was a composite endpoint of treated depression and nonfatal and fatal self-harm.

RESULTS/OUTCOMES

Compared to the thiazide(-like) diuretic group, ACEIs/ARBs use was not associated with a lower risk of the primary outcome (hazard ratio 0.96 (95% confidence interval: 0.79; 1.15)). Results did not differ according to lipophilicity, duration of use, and average daily dose, or class (ACEIs or ARBs).

CONCLUSIONS/INTERPRETATION

New use of ACEIs or ARBs is not associated with a lower risk of depression among individuals with hypertension.

Predator Scent-Induced Sensitization of Hypertension and Anxiety-like Behaviors

Post-traumatic stress disorder (PTSD), an anxiety-related syndrome, is associated with increased risk for cardiovascular diseases. The present study investigated whether predator scent (PS) stress, a model of PTSD, induces sensitization of hypertension and anxiety-like behaviors and underlying mechanisms related to renin-angiotensin systems (RAS) and inflammation. Coyote urine, as a PS stressor, was used to model PTSD. After PS exposures, separate cohorts of rats were studied for hypertensive response sensitization (HTRS), anxiety-like behaviors, and changes in plasma levels and mRNA expression of several components of the RAS and proinflammatory cytokines (PICs) in the lamina terminalis (LT), paraventricular nucleus (PVN), and amygdala (AMY). Rats exposed to PS as compared to control animals exhibited (1) a significantly greater hypertensive response (i.e., HTRS) when challenged with a slow-pressor dose of angiotensin (ANG) II, (2) significant decrease in locomotor activity and increase in time spent in the closed arms of a plus maze as well as general immobility (i.e., behavioral signs of increased anxiety), (3) upregulated plasma levels of ANG II and interleukin-6, and (4) increased expression of message for components of the RAS and PICs in key brain nuclei. All the PS-induced adverse effects were blocked by pretreatment with either an angiotensin-converting enzyme antagonist or a tumor necrosis factor-α inhibitor. The results suggest that PS, used as an experimental model of PTSD, sensitizes ANG II-induced hypertension and produces behavioral signs of anxiety, probably through upregulation of RAS components and inflammatory markers in plasma and brain areas associated with anxiety and blood pressure control.

Dysregulation of ACE-1 in normal aging and the early stages of Alzheimer's disease

An imbalance in the renin-angiotensin system (RAS) is associated with cognitive decline and disease pathology in Alzheimer's disease (AD). In this study, we have investigated changes in the brain angiotensin-converting enzyme-1 (ACE-1) and angiotensin-II (Ang-II), and the counter-regulatory angiotensin-converting enzyme-2 (ACE-2), in the frontal and temporal cortex during normal aging and in the early stages of AD. We studied a cohort of normal aging (n=121) (19-95y age-at-death) from the Sudden Death Brain Bank, University of Edinburgh, UK, and AD and age-matched controls (n=60) from the South West Dementia Brain Bank, University of Bristol, UK, stratified according to Braak tangle stage (BS): 0-II, III-IV (intermediate disease) and V-VI (end-stage disease). ACE-1 and ACE-2 enzyme activity were measured using fluorogenic peptide activity assays. ACE-1, ACE-2, and angiotensin-II (Ang-II) protein level was measured by ELISA. In both regions, ACE-1 protein and Ang-II levels correlated positively with age whereas ACE-1 enzyme activity was inversely related to age. ACE-1 protein correlated positively with Ang-II, whilst ACE-1 activity correlated inversely with Ang-II in normal ageing. ACE-1 enzyme activity was elevated at an early/intermediate stage i.e. BS III-IV compared to BS 0-II in the temporal cortex in AD. ACE-2 protein and enzyme activity were unchanged with aging and in AD. In conclusion, ACE-1 activity is induced in the early stages of AD independently from normal physiological age-related changes in ACE-1 protein.

SARS-CoV-2 interacts with renin-angiotensin system: impact on the central nervous system in elderly patients

SARS-CoV-2 is a recently identified coronavirus that causes the current pandemic disease known as COVID-19. SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as a receptor, suggesting that the initial steps of SARS-CoV-2 infection may have an impact on the renin-angiotensin system (RAS). Several processes are influenced by RAS in the brain. The neurological symptoms observed in COVID-19 patients, including reduced olfaction, meningitis, ischemic stroke, cerebral thrombosis, and delirium, could be associated with RAS imbalance. In this review, we focus on the potential role of disturbances in the RAS as a cause for central nervous system sequelae of SARS-CoV-2 infection in elderly patients.

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.

Controlled Hemorrhage Sensitizes Angiotensin II-Elicited Hypertension through Activation of the Brain Renin-Angiotensin System Independently of Endoplasmic Reticulum Stress

Hemorrhagic shock is associated with activation of renin-angiotensin system (RAS) and endoplasmic reticulum stress (ERS). Previous studies demonstrated that central RAS activation produced by various challenges sensitizes angiotensin (Ang) II-elicited hypertension and that ERS contributes to the development of neurogenic hypertension. The present study investigated whether controlled hemorrhage could sensitize Ang II-elicited hypertension and whether the brain RAS and ERS mediate this sensitization. Results showed that hemorrhaged (HEM) rats had a significantly enhanced hypertensive response to a slow-pressor infusion of Ang II when compared to sham HEM rats. Treatment with either angiotensin-converting enzyme (ACE) 1 inhibitor, captopril, or ACE2 activator, diminazene, abolished the HEM-induced sensitization of hypertension. Treatment with the ERS agonist, tunicamycin, in sham HEM rats also sensitized Ang II-elicited hypertension. However, blockade of ERS with 4-phenylbutyric acid in HEM rats did not alter HEM-elicited sensitization of hypertension. Either HEM or ERS activation produced a greater reduction in BP after ganglionic blockade, upregulated mRNA and protein expression of ACE1 in the hypothalamic paraventricular nucleus (PVN), and elevated plasma levels of Ang II but reduced mRNA expression of the Ang-(1-7) receptor, Mas-R, and did not alter plasma levels of Ang-(1-7). Treatment with captopril or diminazene, but not phenylbutyric acid, reversed these changes. No treatments had effects on PVN protein expression of the ERS marker glucose-regulated protein 78. The results indicate that controlled hemorrhage sensitizes Ang II-elicited hypertension by augmenting RAS prohypertensive actions and reducing RAS antihypertensive effects in the brain, which is independent of ERS mechanism.

(Pro)renin Receptor and Blood Pressure Regulation: A Focus on the Central Nervous System

The renin-angiotensin system (RAS) is classically described as a hormonal system in which angiotensin II (Ang II) is one of the main active peptides. The action of circulating Ang II on its cognate Ang II type-1 receptor (AT1R) in circumventricular organs has important roles in regulating the autonomic nervous system, blood pressure (BP) and body fluid homeostasis, and has more recently been implicated in cardiovascular metabolism. The presence of a local or tissue RAS in various tissues, including the central nervous system (CNS), is well established. However, because the level of renin, the rate-limiting enzyme in the systemic RAS, is very low in the brain, how endogenous angiotensin peptides are generated in the CNS-the focus of this review-has been the subject of considerable debate. Notable in this context is the identification of the (pro)renin receptor (PRR) as a key component of the brain RAS in the production of Ang II in the CNS. In this review, we highlight cellular and anatomical locations of the PRR in the CNS. We also summarize studies using gain- and loss-of function approaches to elucidate the functional importance of brain PRR-mediated Ang II formation and brain RAS activation, as well as PRR-mediated Ang II-independent signaling pathways, in regulating BP. We further discuss recent developments in PRR involvement in cardiovascular and metabolic diseases and present perspectives for future directions.

Vitamin D/VDR regulates peripheral energy homeostasis via central renin-angiotensin system

Introduction

Some epidemiological studies have revealed that vitamin D (VD) deficiency is closely linked with the prevalence of obesity, however, the role of VD in energy homeostasis is yet to be investigated, especially in central nervous system. Given that VD negatively regulates renin in adipose tissue, we hypothesized that central VD might play a potential role in energy homeostasis.

Objectives

The present study aims to investigate the potential role of VD in energy homeostasis in the CNS and elaborate its underlying mechanisms.

Methods

This study was conducted in Cyp27b1^−/− mice, VD-treated and wild-type mice. After the intraventricular injection of renin or its inhibitors, the changes of renin-angiotensin system (RAS) and its down-stream pathway as well as their effects on metabolic rate were examined.

Results

The RAS activity was enhanced in Cyp27b1^−/− mice, exhibiting a increased metabolic rate. Additionally, corticotropin-releasing hormone (CRH), a RAS-mediated protein regulating energy metabolism in the hypothalamus, increased significantly in Cyp27b1^−/− mice. While in VD-treated group, the RAS and sympathetic nerve activities were slightly inhibited, hence the reduced metabolic rate.

Conclusion

Collectively, the present study demonstrates that the VD/vitamin D receptor (VDR) has a significant impact on energy homeostasis through the modulation of RAS activity in the hypothalamus, subsequently altering CRH expression and sympathetic nervous activity.

The association between the renin-angiotensin system and the hypothalamic-pituitary-adrenal axis in anxiety disorders: A systematic review of animal studies

Anxiety is characterized as the emotional response in anticipation of a future threat. This hypervigilant state comprehends a cascade of neuroendocrine and physiological processes, involving the renin-angiotensin system (RAS) and hypothalamic-pituitary-adrenal axis (HPA). Excessive and chronic anxiety may ultimately lead to the development of anxiety disorders. This systematic review aimed to investigate experimental studies using animal models that explored the relationship between RAS and the HPA axis in anxiety disorders. A systematic search was conducted in MEDLINE/PubMed, Embase and Web of Science, and was performed according to PRISMA guidelines. The inclusion criteria was mainly the mention of RAS, HPA axis, and an anxiety disorder in the same study. Quality of studies was evaluated according to the table of risk of bias from SYRCLE. From 12 eligible studies, 7 were included. Research in rats and mice shows that the overactivation of the RAS and HPA axis triggers several neuroendocrine reactions, mainly mediated by AT1 receptors, which promote anxiety-like behaviors and positive feedback for its hyperactivation. On the contrary, the administration of antihypertensive drugs, such as angiotensin AT1 receptor blocker, propitiated the regulation of the RAS and HPA axis, maintaining homeostasis even amid aversive situations. Assessment of risk of bias revealed a pronounced unclear to high risk in several categories, which thus jeopardize the comparability and reproducibility of the results. Nonetheless, the preclinical evidence indicates that the hyperactivation of both RAS and HPA axis during stress exerts deleterious consequences, inducing anxiogenic responses. Moreover, the compiled results show that the modulation of both systems by the administration of AT1 receptor blockers produce anxiolytic effects in animal models and may constitute a new venue for the treatment of anxiety-like disorders.

The Soluble (Pro)Renin Receptor in Health and Diseases: Foe or Friend?

The (pro)renin receptor (PRR) is a single-transmembrane protein that regulates the local renin-angiotensin system and participates in various intracellular signaling pathways, thus exhibiting a significant physiopathologic relevance in cellular homeostasis. A soluble form of PRR (sPRR) is generated through protease-mediated cleavage of the full-length PRR and secreted into extracellular spaces. Accumulating evidence indicates pivotal biologic functions of sPRR in various physiopathological processes. sPRR may be a novel biomarker for multiple diseases. SIGNIFICANCE STATEMENT: Circulating sPRR concentrations are elevated in patients and animals under various physiopathological conditions. This minireview highlights recent advances in sPRR functions in health and pathophysiological conditions. Results suggest that sPRR may be a novel biomarker for multiple diseases, but further studies are needed to determine the diagnostic value of sPRR.

The Renin-Angiotensin System in the Tumor Microenvironment of Glioblastoma

Simple Summary

Glioblastoma (GB) is the most aggressive brain cancer in humans. Patient survival outcomes have remained dismal despite intensive research over the past 50 years, with a median overall survival of only 14.6 months. We highlight the critical role of the renin–angiotensin system (RAS) on GB cancer stem cells and the tumor microenvironment which, in turn, influences cancer stem cells in driving tumorigenesis and treatment resistance. We present recent developments and underscore the need for further research into the GB tumor microenvironment. We discuss the novel therapeutic targeting of the RAS using existing commonly available medications and utilizing model systems to further this critical investigation.

Abstract

Glioblastoma (GB) is an aggressive primary brain tumor. Despite intensive research over the past 50 years, little advance has been made to improve the poor outcome, with an overall median survival of 14.6 months following standard treatment. Local recurrence is inevitable due to the quiescent cancer stem cells (CSCs) in GB that co-express stemness-associated markers and components of the renin–angiotensin system (RAS). The dynamic and heterogeneous tumor microenvironment (TME) plays a fundamental role in tumor development, progression, invasiveness, and therapy resistance. There is increasing evidence showing the critical role of the RAS in the TME influencing CSCs via its upstream and downstream pathways. Drugs that alter the hallmarks of cancer by modulating the RAS present a potential new therapeutic alternative or adjunct to conventional treatment of GB. Cerebral and GB organoids may offer a cost-effective method for evaluating the efficacy of RAS-modulating drugs on GB. We review the nexus between the GB TME, CSC niche, and the RAS, and propose re-purposed RAS-modulating drugs as a potential therapeutic alternative or adjunct to current standard therapy for GB.

Single-cell RNA Sequencing of SARS-CoV-2 Cell Entry Factors in the Preconceptional Human Endometrium

STUDY QUESTION

Are SARS-CoV-2 canonical cell entry machinery, consisting of ACE2, TMPRSS2, NRP1 and LY6E, or alternative potential cell entry machinery, consisting of BSG, ANPEP, CD209, CLEC4G, TMPRSS4, TMPRSS11A, FURIN, CTSB, CTSL and IFITM1, expressed in the human endometrium across the menstrual cycle?

SUMMARY ANSWER

Analysis of cell entry factors for SARS-CoV-2 by single-cell RNA-sequencing (scRNAseq) in the preconceptional human endometrium reveals low risk of infection.

WHAT IS KNOWN ALREADY

Gene expression datasets from bulk endometrial tissue show no significant expression of the SARS-CoV-2 receptor ACE2 and TMPRSS2. This is in contrast to reported expression of ACE2 at the single-cell level in the decidua and trophoblast cells at the maternal–fetal interface in early pregnancy, as well as vertical transmission of SARS-CoV-2 during pregnancy.

STUDY DESIGN, SIZE, DURATION

This analysis of SARS-CoV-2 cell entry machinery gene expression was conducted by scRNAseq in 73 181 human endometrial cells isolated from endometrial biopsies obtained from 27 donors across the menstrual cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ScRNAseq examined the expression of genes encoding cell entry machinery for SARS-CoV-2. The raw data were from a previously published dataset.

MAIN RESULTS AND THE ROLE OF CHANCE

ScRNAseq analysis showed no significant expression of ACE2 in stromal or unciliated epithelial cells in any phase of the menstrual cycle. TMPRSS2 was expressed in epithelial cells during the early proliferative and mid-secretory phases. Interestingly, the expression of NRP1 was observed in both stromal and epithelial cells across all phases of the menstrual cycle, and LY6E was highly expressed in stromal cells. In the mid-secretory phase, coexpression of ACE2 and TMPRSS2 was detected in 0.07% of luminal epithelial cells. No cells simultaneously expressed ACE2, NRP1 and TMPRSS2 at the time of embryo implantation. Focusing on non-canonical cell entry machinery, BSG was highly expressed in all cell types across the menstrual cycle and may interact with CTSB or CTSL proteases, but viral infection using this machinery has not yet been confirmed.

LARGE SCALE DATA

All raw data in this study can be found at NCBI’s Gene Expression Omnibus (series accession code GSE111976) and Sequence Read Archive (accession code SRP135922).

LIMITATIONS, REASONS FOR CAUTION

Our findings at the single-cell level imply low efficiency of SARS-CoV-2 endometrial infection using canonical receptors in a cohort of healthy reproductive-age women; however, infection of endometrial cells can only be assessed in the presence of the virus. All samples were processed for scRNAseq, so no samples are remaining to analyze protein expression or spatial transcriptomics.

WIDER IMPLICATIONS OF THE FINDINGS

Our results offer a useful resource to guide reproductive decisions when assessing risk of endometrial infection by SARS-CoV-2 during the preconceptional period in asymptomatic COVID-19 carriers.

STUDY FUNDING/COMPETING INTEREST(S)

This study was jointly supported by the March of Dimes, Chan Zuckerberg Biohub and MINECO/FEDER (SAF-2015-67164-R, to C.S.) (Spanish Government), and the European Union’s Horizon 2020 Framework Programme for Research and Innovation (Grant agreement 874867). W.W. was supported by the Stanford Bio-X Graduate Bowes Fellowship and Chan Zuckerberg Biohub. F.V. was supported by the Miguel Servet Program Type II of ISCIII (CPII18/00020) and the FIS project (PI18/00957). A patent disclosure has been filed for the study with the title ‘Methods for assessing endometrial transformation’ and the global patent number ‘EP 3807648 A2’ under the inventors S.R.Q., C.S., W.W. and F.V. C.S. is the Founder and Head of the Scientific Advisory Board of Igenomix SL. S.R.Q is the Director of Mirvie. I.M. is partially employed by Igenomix SL. B.R. has no interests to declare.

Studies of salt and stress sensitivity on arterial pressure in renin-b deficient mice

Excessive sodium intake is known to increase the risk for hypertension, heart disease, and stroke. Individuals who are more susceptible to the effects of high salt are at higher risk for cardiovascular diseases even independent of their blood pressure status. Local activation of the renin-angiotensin system (RAS) in the brain, among other mechanisms, has been hypothesized to play a key role in contributing to salt balance. We have previously shown that deletion of the alternative renin isoform termed renin-b disinhibits the classical renin-a encoding preprorenin in the brain resulting in elevated brain RAS activity. Thus, we hypothesized that renin-b deficiency results in higher susceptibility to salt-induced elevation in blood pressure. Telemetry implanted Ren-bNull and wildtype littermate mice were first offered a low salt diet for a week and subsequently a high salt diet for another week. A high salt diet induced a mild blood pressure elevation in both Ren-bNull and wildtype mice, but mice lacking renin-b did not exhibit an exaggerated pressor response. When renin-b deficient mice were exposed to a high salt diet for a longer duration (4 weeks), there was a trend for increased myocardial enlargement in Ren-bNull mice when compared with control mice, but this did not reach statistical significance. Multiple studies have also demonstrated the association of environmental stress with hypertension. Activation of the RAS in the rostral ventrolateral medulla and the hypothalamus is required for stress-induced hypertension. Thus, we next questioned whether the lack of renin-b would result in exacerbated response to an acute restraint-stress. Wildtype and Ren-bNull mice equally exhibited elevated blood pressure in response to restraint-stress, which was similar in mice fed either a low or high salt diet. These studies suggest that mechanisms unrelated to salt and acute stress alter the cardiovascular phenotype in mice lacking renin-b.

Activation of the Central Renin-Angiotensin System Causes Local Cerebrovascular Dysfunction

[Figure: see text].

Increased angiotensin II formation in the brain modulates cardiovascular homeostasis and erythropoiesis

In spite of the fact that the modulatory effects of angiotensin II (Ang II) on the sympathetic nerve activity to targeted organs involved in blood pressure (BP) regulation is well acknowledged, the local production of this peptide in the brain and the consequences of enhanced central Ang II beyond the cardiovascular system are not yet well comprehended. In the present study, we generated and validated a new transgenic mouse line overexpressing the rat full-length angiotensinogen (Agt) protein specifically in the brain (Agt-Tg). Adult Agt-Tg mice presented overall increased gene expression of total Agt in the brain including brainstem and hypothalamus. In addition, the excess of Agt led to abundantly detectable brain Ang II levels as well as increased circulating copeptin levels. Agt-Tg displayed raised BP in acute recordings, while long-term telemetrically measured basal BP was indistinguishable from wild-types. Agt-Tg has altered peripheral renin–angiotensin system and vasomotor sympathetic tone homeostasis because renal gene expression analysis, plasma Ang II measurements and ganglionic blockade experiments revealed suppressed renin expression and reduced Ang II and higher neurogenic pressure response, respectively. Plasma and urine screens revealed apparently normal fluid and electrolyte handling in Agt-Tg. Interestingly, hematological analyses showed increased hematocrit in Agt-Tg caused by enhanced erythropoiesis, which was reverted by submitting the transgenic mice to a long-term peripheral sympathectomy protocol. Collectively, our findings suggest that Agt-Tg is a valuable tool to study not only brain Ang II formation and its modulatory effects on cardiovascular homeostasis but also its role in erythropoiesis control via autonomic modulation.

Angiotensin receptors in the kidney and vasculature in hypertension and kidney disease

Kidney disease, blood pressure determination, hypertension pathogenesis, and the renin-angiotensin system (RAS) are inextricably linked. Hence, understanding the RAS is pivotal to unraveling the pathophysiology of hypertension and the determinants to maintaining normal blood pressure. The RAS has been the subject of intense investigation for over a century. Moreover, medications that block the RAS are mainstay therapies in clinical medicine and have been shown to reduce morbidity and mortality in patients with diabetes, cardiovascular, and kidney diseases. The main effector peptide of the RAS is the interaction of the octapeptide- Ang II with its receptor. The type 1 angiotensin receptor (AT₁R) is the effector receptor for Ang II. These G protein-coupled receptors (GPCRs) are ubiquitously expressed in a variety of cell lineages and tissues relevant to cardiovascular disease throughout the body. The advent of cell specific deletion of genes using Cre LoxP technology in mice has allowed for the identification of discreet actions of AT₁Rs in blood pressure control and kidney disease. The kidney is one of the major targets of the RAS, which is responsible in maintaining fluid, electrolyte balance, and blood pressure. In this review we will discuss the role of AT₁Rs in the kidney, vasculature, and immune cells and address their effects on hypertension and kidney disease.