The renin-angiotensin system (first of two parts)

ICH-LR2S2: a new risk score for predicting stroke-associated pneumonia from spontaneous intracerebral hemorrhage

Purpose

We develop a new risk score to predict patients with stroke-associated pneumonia (SAP) who have an acute intracranial hemorrhage (ICH).

Method

We applied logistic regression to develop a new risk score called ICH-LR2S2. It was derived from examining a dataset of 70,540 ICH patients between 2015 and 2018 from the Chinese Stroke Center Alliance (CSCA). During the training of ICH-LR2S2, patients were randomly divided into two groups – 80% for the training set and 20% for model validation. A prospective test set was developed using 12,523 patients recruited in 2019. To further verify its effectiveness, we tested ICH-LR2S2 on an external dataset of 24,860 patients from the China National Stroke Registration Management System II (CNSR II). The performance of ICH-LR2S2 was measured by the area under the receiver operating characteristic curve (AUROC).

Results

The incidence of SAP in the dataset was 25.52%. A 24-point ICH-LR2S2 was developed from independent predictors, including age, modified Rankin Scale, fasting blood glucose, National Institutes of Health Stroke Scale admission score, Glasgow Coma Scale score, C-reactive protein, dysphagia, Chronic Obstructive Pulmonary Disease, and current smoking. The results showed that ICH-LR2S2 achieved an AUC = 0.749 [95% CI 0.739–0.759], which outperforms the best baseline ICH-APS (AUC = 0.704) [95% CI 0.694–0.714]. Compared with the previous ICH risk scores, ICH-LR2S2 incorporates fasting blood glucose and C-reactive protein, improving its discriminative ability. Machine learning methods such as XGboost (AUC = 0.772) [95% CI 0.762–0.782] can further improve our prediction performance. It also performed well when further validated by the external independent cohort of patients (n = 24,860), ICH-LR2S2 AUC = 0.784 [95% CI 0.774–0.794].

Conclusion

ICH-LR2S2 accurately distinguishes SAP patients based on easily available clinical features. It can help identify high-risk patients in the early stages of diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03389-5.

Epigenetic modifications of the renin-angiotensin system in cardiometabolic diseases

Cardiometabolic diseases (CMDs) are among the most prevalent and the highest mortality diseases. Single disease etiology such as gene mutation, polymorphisms, or environmental exposure has failed to explain the origin of CMD. This can be evident in the discrepancies in disease susceptibility among individuals exposed to the same environmental insult or who acquire the same genetic variation. Epigenetics is the intertwining of genetic and environmental factors that results in diversity in the disease course, severity, and prognosis among individuals. Environmental exposures modify the epigenome and thus provide a link for translating environmental impact on changes in gene expression and precipitation to pathological conditions. Renin-angiotensin system (RAS) is comprising genes responsible for the regulation of cardiovascular, metabolic, and glycemic functions. Epigenetic modifications of RAS genes can lead to overactivity of the system, increased sympathetic activity and autonomic dysfunction ultimately contributing to the development of CMD. In this review, we describe the three common epigenetic modulations targeting RAS components and their impact on the susceptibility to cardiometabolic dysfunction. Additionally, we highlight the therapeutic efforts of targeting these epigenetic imprints to the RAS and its effects.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Development of a novel AlphaLISA ImmunoAssay for Big angiotensin-25

We previously described the discovery of Big angiotensin-25 (Bang-25), an angiotensin-related peptide isolated from human urine. Bang-25 consists of the first 25 amino acids of the N-terminus of angiotensinogen (Aogen), with N-linked glycosylation on the 14th amino acid and a cysteine conjugated to the 18th amino acid. Bang-25 is rapidly converted into angiotensin II (Ang II) by chymase. Because Bang-25 is widely distributed in human tissues, including islet cells in the pancreas and podocytes in the kidney, we hypothesized that it may participate in the Ang II production system in these tissues. To test this hypothesis, we developed a specific assay for Bang-25 and used it to examine the urinary concentrations of Bang-25 in patients with diabetes mellitus (DM). The assay used the Amplified Luminescent Proximity Homogeneous Assay (Alpha)-based ELISA method (AlphaLISA) of PerkinElmer Japan and included antibodies specific to the N-terminus of Ang II and the C-terminus of Bang-25. The AlphaLISA ImmunoAssay specifically recognized Bang-25 and had no cross-reactivity with Aogen or Ang I. Bang-25 was detected in healthy volunteers' urine samples but not in their plasma samples. In patients with DM, the urinary Bang-25 concentration was significantly higher than in healthy volunteers. Moreover, the results indicated that the Bang-25 concentration in the urine may offer a different perspective on disease status from that provided by urinary albumin. This assay could provide a useful tool for determining urinary Bang-25, which may prove an important biomarker for diabetic kidney disease.

A new mechanism for the sex differences in angiotensin II-induced hypertension: the role of macula densa NOS1β-mediated tubuloglomerular feedback

Females are protected against the development of angiotensin II (ANG II)-induced hypertension compared with males, but the mechanisms have not been completely elucidated. In the present study, we hypothesized that the effect of ANG II on the macula densa nitric oxide (NO) synthase 1β (NOS1β)-mediated tubuloglomerular feedback (TGF) mechanism is different between males and females, thereby contributing to the sexual dimorphism of ANG II-induced hypertension. We used microperfusion, micropuncture, clearance of FITC-inulin, and radio telemetry to examine the sex differences in the changes of macula densa NOS1β expression and activity, TGF response, natriuresis, and blood pressure (BP) after a 2-wk ANG II infusion in wild-type and macula densa-specific NOS1 knockout mice. In wild-type mice, ANG II induced higher expression of macula densa NOS1β, greater NO generation by the macula densa, and a lower TGF response in vitro and in vivo in females than in males; the increases of glomerular filtration rate, urine flow rate, and Na⁺ excretion in response to an acute volume expansion were significantly greater and the BP responses to ANG II were significantly less in females than in males. In contrast, these sex differences in the effects of ANG II on TGF, natriuretic response, and BP were largely diminished in knockout mice. In addition, tissue culture of human kidney biopsies (renal cortex) with ANG II resulted in a greater increase in NOS1β expression in females than in males. In conclusion, macula densa NOS1β-mediated TGF is a novel and important mechanism for the sex differences in ANG II-induced hypertension.

Management of Cardiac Toxicity Induced by Chemotherapy

Cardiotoxicity encompasses a spectrum of adverse cardiological effects experienced by cancer patients during and after receiving antineoplastic treatments. The intersection of cancer care with the management of the multiple comorbid non-communicable diseases carried by patients or related to cancer treatments motivates the need for an integrated and multidisciplinary approach to therapeutic clinical decision-making. This present review aimed to provide a perspective and an update of the current pharmacotherapy approaches for the prevention and management of cardiotoxicity from antiblastic chemotherapy; as such, it addresses myocardial, vascular, and arrhythmic disorders associated to chemotherapy, by navigating the current knowledge and clinical indications in support of the medical interventions. Clinical scenarios of pharmacological interventions take place with patients receiving anthracycline and, by extrapolation, other agents with cardiotoxic potentials and non-chemotherapy agents, including various small molecules and immunotherapy agents. Analysis of these scenarios aims to provide practical evidence-based guidance for the management of drug-induced cardiac dysfunctions. The possible role of new biomarkers for the early recognition of cardiotoxicity is mentioned across the clinical studies, with reference to the pharmacological biomarker-driven interventions delivered. To best inform survivorship care, the management and context of cardio-oncology services are discussed within the broader network of providers and settings of care.

Novel Medical Treatments for Hypertension and Related Comorbidities

Purpose of Review

The purpose of this review is to summarize the most recent data available on advances in development of novel medical treatments for hypertension and related comorbidities.

Recent Findings

Approximately half of all hypertensive patients have not achieved goal blood pressure with current available antihypertensive medications. Recent landmark studies and new hypertension guidelines have called for stricter blood pressure control, creating a need for better strategies for lowering blood pressure. This has led to a shift in focus, in recent years, to the development of combination pills as a means of achieving improved blood pressure control by increasing adherence to prescribed medications along with further research and development of promising novel drugs based on discovery of new molecular targets such as the counter-regulatory renin-angiotensin system.

Summary

Fixed-dose combination pills and novel treatments based on recently discovered pathogenic mechanisms of hypertension that have demonstrated promising results as treatments for hypertension and related comorbidities will be discussed in this review.

Effect of Oral Captopril (SQ 14225) on Intraocular Pressure in Man

The effects of the angiotensin converting enzyme (ACE) inhibitor captopril (SQ 14225) on intraocular pressure (IOP) were studied. Four groups were analyzed: group A, ten control subjects; group B, ten hypertensive patients with normal IOP; group C, ten normotensive patients with primary open angle glaucoma (POAG); and group D, ten hypertensive patients with POAG. Systolic and diastolic blood pressure, heart rate, pupil diameter, IOP and total outflow facility were recorded at baseline and at 1-h intervals up to 3h after an oral dose of 25 mg captopril or placebo, given in a randomized, double-blind cross-over fashion. The alternative treatment was given a week later. Captopril significantly lowered IOP in all patients, with no effects on heart rate and pupil diameter. Blood pressure changed only in patients with hypertension (groups B and D). Total outflow facility, measured by conventional tonography, increased significantly in all groups. These findings indicate that oral captopril could represent a new antiglaucomatous compound.

Role of MicroRNA in Endothelial Dysfunction and Hypertension

Purpose of Review

Hypertension is either a cause or a consequence of the endothelial dysfunction and a major risk factor for cardiovascular disease (CVD). In vitro and in vivo studies established that microRNAs (miRNAs) are decisive for endothelial cell gene expression and function in various pathological conditions associated with CVD.

This review provides an overview of the miRNA role in controlling the key connections between endothelial dysfunction and hypertension.

Recent Findings

Herein we summarize the present understanding of mechanisms underlying hypertension and its associated endothelial dysfunction as well as the miRNA role in endothelial cells with accent on the modulation of renin-angiotensin-aldosterone-system, nitric oxide, oxidative stress and on the control of vascular inflammation and angiogenesis in relation to endothelial dysfunction in hypertension. In particular, latest insights in the identification of endothelial-specific microRNAs and their targets are added to the understanding of miRNA significance in hypertension.

Summary

This comprehensive knowledge of the role of miRNAs in endothelial dysfunction and hypertension and of molecular mechanisms proposed for miRNA actions may offer novel diagnostic biomarkers and therapeutic targets for controlling hypertension-associated endothelial dysfunction and other cardiovascular complications.

Associations of aldosterone and renin concentrations with inflammation-the Study of Health in Pomerania and the German Conn's Registry

PURPOSE

Chronic inflammation is an age-independent and body mass index-independent contributor to the development of multi-morbidity. Alterations of the renin-angiotensin-aldosterone system are observed within the context of proinflammatory states. We assessed circulating aldosterone, renin, and inflammatory biomarker concentrations in healthy, normotensive subjects and patients with primary aldosteronism.

METHODS

We included 1177 normotensive individuals from the population-based Study of Health in Pomerania (first follow-up, Study of Health in Pomerania-1) and 103 primary aldosteronism patients from the German Conn's Registry. A 1:1 matching for sex, age, body mass index, smoking status, diabetes mellitus, and the estimated glomerular filtration rate was performed to determine whether primary aldosteronism patients exhibit higher inflammatory biomarker concentrations than normotensive controls. The associations of plasma aldosterone concentration or plasma renin concentration with circulating fibrinogen concentrations, white blood cell count, and high sensitive C-reactive protein concentrations in the normotensive sample were determined with multivariable linear and logistic regression analyses.

RESULTS

1:1 matched primary aldosteronism patients demonstrated significantly (p < 0.01) higher plasma aldosterone concentration (198 vs. 47 ng/l), lower plasma renin concentration (3.1 vs. 7.7 ng/l) and higher high sensitive C-reactive protein concentrations (1.5 vs. 1.0 mg/l) than normotensive controls. Within the normotensive cohort, plasma renin concentration but not plasma aldosterone concentration was positively associated with fibrinogen concentrations and white blood cell count. Further, a J-shaped association between plasma renin concentration and high sensitive C-reactive protein concentrations was detected.

CONCLUSIONS

High plasma aldosterone concentration in a primary aldosteronism cohort and high plasma renin concentration in normotensive subjects are associated with increased concentrations of inflammatory biomarkers. This suggests a link between the renin-angiotensin-aldosterone system and inflammatory processes in patients with primary aldosteronism and even in normotensive subjects.

Molecular targets of antihypertensive peptides: understanding the mechanisms of action based on the pathophysiology of hypertension

There is growing interest in using functional foods or nutraceuticals for the prevention and treatment of hypertension or high blood pressure. Although numerous preventive and therapeutic pharmacological interventions are available on the market, unfortunately, many patients still suffer from poorly controlled hypertension. Furthermore, most pharmacological drugs, such as inhibitors of angiotensin-I converting enzyme (ACE), are often associated with significant adverse effects. Many bioactive food compounds have been characterized over the past decades that may contribute to the management of hypertension; for example, bioactive peptides derived from various food proteins with antihypertensive properties have gained a great deal of attention. Some of these peptides have exhibited potent in vivo antihypertensive activity in both animal models and human clinical trials. This review provides an overview about the complex pathophysiology of hypertension and demonstrates the potential roles of food derived bioactive peptides as viable interventions targeting specific pathways involved in this disease process. This review offers a comprehensive guide for understanding and utilizing the molecular mechanisms of antihypertensive actions of food protein derived peptides.

Biomarkers of activation of renin-angiotensin-aldosterone system in heart failure: how useful, how feasible?

Renin-angiotensin-aldosterone system (RAAS), participated by kidney, liver, vascular endothelium, and adrenal cortex, and counter-regulated by cardiac endocrine function, is a complex endocrine system regulating systemic functions, such as body salt and water homeostasis and vasomotion, in order to allow the accomplishment of physiological tasks, such as orthostasis, physical and emotional stimuli, and to react towards the hemorrhagic insult, in tight conjunction with other neurohormonal axes, namely the sympathetic nervous system, the endothelin and vasopressin systems. The systemic as well as the tissue RAAS are also dedicated to promote tissue remodeling, particularly relevant after damage, when chronic activation may configure as a maladaptive response, leading to fibrosis, hypertrophy and apoptosis, and organ dysfunction. RAAS activation is a fingerprint of systemic arterial hypertension, kidney dysfunction, vascular atherosclerotic disease, and is definitely an hallmark of heart failure, which rapidly shifts from organ disease to a disorder of neurohormonal regulatory systems. Chronic RAAS activation is an indirect or direct target of most effective pharmacological treatments in heart failure, such as beta-blockers, inhibitors of angiotensin converting enzyme, angiotensin receptor blockers, direct renin inhibitors, and mineralocorticoid receptor blockers. Biomarkers of RAAS activation are available, with different feasibility and accuracy, such as plasma renin activity, renin, angiotensin II, and aldosterone, which all accompany the increasing clinical severity of heart failure disease, and are well recognized prognostic factors, even in patients with optimal therapy. Polymorphisms influencing the expression and activity of RAAS pathways have been recognized as clinically relevant biomarkers, likely influencing either the individual clinical phenotype, or the response to drugs. This solid, growing evidence strongly suggests the rationale for the use of biomarkers of the RAAS activation, as a guide to tailor individual therapy in the current practice, and their implementation as a rule-in marker for future trials on novel drugs in the heart failure setting.

Potential role of NADPH oxidase in pathogenesis of pancreatitis

Studies have demonstrated that reactive oxygen species (ROS) are closely related to inflammatory disorders. Nicotinamide adenine dinucleotide phosphate oxidase (NOX), originally found in phagocytes, is the main source of ROS in nonphagocytic cells. Besides directly producing the detrimental highly reactive ROS to act on biomolecules (lipids, proteins, and nucleic acids), NOX can also activate multiple signal transduction pathways, which regulate cell growth, proliferation, differentiation and apoptosis by producing ROS. Recently, research on pancreatic NOX is no longer limited to inflammatory cells, but extends to the aspect of pancreatic acinar cells and pancreatic stellate cells, which are considered to be potentially associated with pancreatitis. In this review, we summarize the literature on NOX protein structure, activation, function and its role in the pathogenesis of pancreatitis.

The Renin-Angiotensin-aldosterone system in vascular inflammation and remodeling

The RAAS through its physiological effectors plays a key role in promoting and maintaining inflammation. Inflammation is an important mechanism in the development and progression of CVD such as hypertension and atherosclerosis. In addition to its main role in regulating blood pressure and its role in hypertension, RAAS has proinflammatory and profibrotic effects at cellular and molecular levels. Blocking RAAS provides beneficial effects for the treatment of cardiovascular and renal diseases. Evidence shows that inhibition of RAAS positively influences vascular remodeling thus improving CVD outcomes. The beneficial vascular effects of RAAS inhibition are likely due to decreasing vascular inflammation, oxidative stress, endothelial dysfunction, and positive effects on regeneration of endothelial progenitor cells. Inflammatory factors such as ICAM-1, VCAM-1, TNFα, IL-6, and CRP have key roles in mediating vascular inflammation and blocking RAAS negatively modulates the levels of these inflammatory molecules. Some of these inflammatory markers are clinically associated with CVD events. More studies are required to establish long-term effects of RAAS inhibition on vascular inflammation, vascular cells regeneration, and CVD clinical outcomes. This review presents important information on RAAS's role on vascular inflammation, vascular cells responses to RAAS, and inhibition of RAAS signaling in the context of vascular inflammation, vascular remodeling, and vascular inflammation-associated CVD. Nevertheless, the review also equates the need to rethink and rediscover new RAAS inhibitors.

Renin gene polymorphisms in bangladeshi hypertensive population

OBJECTIVE

Linkages of renin gene polymorphisms with hypertension have been implicated in several populations with contrasting results. Present study aims to assess the pattern of renin gene polymorphisms in Bangladeshi hypertensive individuals.

METHODOLOGY

Introns 1, 9 of renin gene and 4063 bases upstream of promoter sequence of renin gene were amplified from the genomic DNA of the total 124 (hypertensive and normotensive) subjects using respective primers. Polymerase chain reaction-based restriction fragment length polymorphisms were performed using BglI, MboI and TaqI restriction enzymes.

RESULTS

Homozygosity was common in renin gene regarding BglI (bb=48.4%, Bb=37.9%, BB=13.7%, χ (2) =1.91, P>0.05), TaqI (TT=81.5%, Tt=14.5%, tt=4.0%, χ (2) =7.50, P<0.01) and MboI (mm=63.7%, Mm=32.3%, MM=4.0%, χ (2) =0.00, P>0.05) polymorphisms among total study population. For BglI and TaqI genotype distribution, hypertensive subjects (BglI: χ (2) =6.66, P<0.05; TaqI: χ (2) = 10.28, P<0.005) significantly deviate from Hardy-Weinberg Equilibrium law compared to normotensive subjects (BglI: χ (2) =0.51, P>0.05; TaqI: χ (2) =0.20, P>0.05). On the other hand, with respect to MboI polymorphisms of renin gene, only normotensive subjects deviate from the law (patients: χ (2) =1.28, P>0.05; vs controls: χ (2) =6.81, P<0.01). In the context of allelic frequency, common T allele was clearly prevalent (T frequency=0.86, t frequency = 0.14) for TaqI, but rare alleles b and m were more frequent for both BglI (b frequency=0.69, B frequency=0.31) and MboI (m frequency=0.80 M frequency=0.20) polymorphisms, respectively.

CONCLUSION

Thus, we report that Bangladeshi hypertensive subjects did not show any distinct pattern of renin gene polymorphisms compared to their healthy control subjects with regard to their genotypic and allelic frequencies.

Characterization of sperm surface protein patterns of ejaculated and capacitated boar sperm, with the detection of ZP binding candidates

Complementary molecules on the surface of both gametes are responsible for the interaction of sperm protein receptors with zona pellucida (ZP) saccharide structures, and many primary sperm receptors for ZP glycoproteins have been disclosed in various mammals. For our study, proteins were obtained from the surface of ejaculated and in vitro capacitated boar sperm. The isolated proteins were characterized by 1D- and 2D-electrophoretic protein profiles, and by glycoprotein staining. Our results show quantitative and qualitative differences in protein and glycoprotein patterns between ejaculated and capacitated sperm. Far-western blotting with ZP glycoproteins identified 17 interactions in the subproteome of the ejaculated sperm and 14 interactions in the subproteome of the capacitated sperm. High-molecular-mass proteins, coincident with binding to ZP, were sequence-identified. Angiotensin-converting enzyme (ACE), polycystic kidney disease receptor and egg jelly receptor (PKDREJ), and acrosin precursor were successfully identified. This is the first time PKDREJ has been identified on the surface of boar spermatozoa.

Structural insights into central hypertension regulation by human aminopeptidase A

Hypertension is regulated through both the central and systemic renin-angiotensin systems. In the central renin-angiotensin system, zinc-dependent aminopeptidase A (APA) up-regulates blood pressure by specifically cleaving the N-terminal aspartate, but not the adjacent arginine, from angiotensin II, a process facilitated by calcium. Here, we determined the crystal structures of human APA and its complexes with different ligands and identified a calcium-binding site in the S1 pocket of APA. Without calcium, the S1 pocket can bind both acidic and basic residues through formation of salt bridges with the charged side chains. In the presence of calcium, the binding of acidic residues is enhanced as they ligate the cation, whereas the binding of basic residues is no longer favorable due to charge repulsion. Of the peptidomimetic inhibitors of APA, amastatin has higher potency than bestatin by fitting better in the S1 pocket and interacting additionally with the S3' subsite. These results explain the calcium-modulated substrate specificity of APA in central hypertension regulation and can guide the design and development of brain-targeting antihypertensive APA inhibitors.

Neuroendocrine and haemodynamic changes in single-lead atrial pacing and dual-chamber pacing modes

OBJECTIVES

Neuroendocrine and haemodynamic changes were compared between single-lead atrial (AAI) or dual-chamber (DDD) pacing modes in patients with sick sinus syndrome, in a crossover study.

METHODS

Inpatients scheduled for their first pacemaker implantation were screened for the following inclusion criteria: sick sinus syndrome; intact atrioventricular conduction; normal QRS interval. All study patients were implanted with a dual-chamber pacemaker, programmed for AAI or DDD pacing mode. Patients were allocated randomly to AAI followed by DDD pacing or to DDD followed by AAI pacing, each mode being applied for 72 h. Echocardiographic, electrocardiographic and neuroendocrine parameters were tested at the end of each pacing mode.

RESULTS

From 152 inpatients screened for inclusion, 28 were selected for treatment. Plasma levels of atrial natriuretic peptide (ANP), endothelin, aldosterone and angiotension II were significantly lower, and aortic flow velocity-time integral was significantly higher, in AAI mode than in DDD mode. Aortic pre-ejection interval, interventricular mechanical delay and QRS duration were significantly higher in DDD than in AAI mode.

CONCLUSIONS

In patients with sick sinus syndrome, DDD pacing mode can induce neuroendocrine system activation, and left ventricular dysfunction and dyssynchrony. These findings discourage the routine use of DDD pacing in patients with sick sinus syndrome.

The role of stroma in pancreatic cancer: diagnostic and therapeutic implications

Pancreatic ductal adenocarcinoma (PDAC) is one of the five most lethal malignancies worldwide and survival has not improved substantially in the past 30 years. Desmoplasia (abundant fibrotic stroma) is a typical feature of PDAC in humans, and stromal activation commonly starts around precancerous lesions. It is becoming clear that this stromal tissue is not a bystander in disease progression. Cancer-stroma interactions effect tumorigenesis, angiogenesis, therapy resistance and possibly the metastatic spread of tumour cells. Therefore, targeting the tumour stroma, in combination with chemotherapy, is a promising new option for the treatment of PDAC. In this Review, we focus on four issues. First, how can stromal activity be used to detect early steps of pancreatic carcinogenesis? Second, what is the effect of perpetual pancreatic stellate cell activity on angiogenesis and tissue perfusion? Third, what are the (experimental) antifibrotic therapy options in PDAC? Fourth, what lessons can be learned from Langton's Ant (a simple mathematical model) regarding the unpredictability of genetically engineered mouse models?

Inhibition of the renin-angiotensin-aldosterone system: is there room for dual blockade in the cardiorenal continuum?

Antagonism of renin-angiotensin-aldosterone system is exerted through angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, renin inhibitors and mineralocorticoid receptor antagonists. These drugs have been successfully tested in numerous trials and in different clinical settings. The original indications of renin-angiotensin-aldosterone system blockers have progressively expanded from the advanced stages to the earlier stages of cardiorenal continuum. To optimize the degree of blockade of renin-angiotensin-aldosterone system, dose uptitrations of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists or the use of a dual blockade, initially identified with the combination of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists, have been proposed. The data from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) study do not support this specific dual blockade approach. However, the dual blockade of angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists with direct renin inhibitors is currently under investigation while that based on an aldosterone blocker with any of the previous three drugs requires more evidence beyond heart failure. In this review, we revisited potential advantages of dual blockade of renin-angiotensin-aldosterone system in arterial hypertension and diabetes.

A Hypertension Gene: Are We There Yet?

Cardiovascular diseases are the leading cause of death worldwide. Essential hypertension is a major risk factor for the development of other cardiovascular diseases and is caused by a combination of environmental and genetic factors, with up to 50% of blood pressure variance currently attributed to an individual's genetic makeup. By studying genes that cause monogenic forms of hypertension and pathways relevant to blood pressure control, a number of polymorphisms have been identified that increase an individual's risk of developing high blood pressure. We report on candidate gene association studies and genome-wide association studies that have been performed to date in the field of hypertension research. It is becoming clear that for the majority of people there is no single gene polymorphism that causes hypertension, but rather a number of common genetic variants, each having a small effect. Using pharmacogenomics to personalize the treatment of hypertension holds promise for achieving and sustaining normotensive pressures quickly, while minimizing the risk of adverse reactions and unwanted side-effects. This will decrease the risk of stroke and myocardial infarction in individuals and lead to a reduced burden of disease upon society as a whole.

Plasma and tissue concentrations of proangiotensin-12 in rats treated with inhibitors of the renin-angiotensin system

It has been suggested that proangiotensin-12 (proang-12), a novel angiotensin peptide recently discovered in rat tissues, may function as a component of the tissue renin-angiotensin system (RAS). To investigate the role of proang-12 in the production of angiotensin II (Ang II), we measured its plasma and tissue concentrations in Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, with and without RAS inhibition. The 15-week-old male WKY and SHR rats were left untreated or were treated for 7 days with 30 mg kg(-1) per day losartan, an angiotensin receptor blocker, or with 20 mg kg(-1) per day imidapril, an angiotensin-converting enzyme (ACE) inhibitor. Both treatments increased renin activity and the concentrations of angiotensin I (Ang I) and Ang II in the plasma of WKY and SHR rats, but neither affected plasma proang-12 levels. In contrast to the comparatively low level of proang-12 seen in plasma, cardiac and renal levels of proang-12 were higher than those of Ang I and Ang II. In addition, despite activation of the RAS in the systemic circulation, tissue concentrations of proang-12 were significantly reduced following treatment with losartan or imidapril. Similar reductions were also observed in the tissue concentrations of Ang II in both strains, without a reduction in Ang I. These results suggest that tissue concentrations of proang-12 and Ang II are regulated independently of the systemic RAS in WKY and SHR rats, which is consistent with the notion that proang-12 is a component of only the tissue RAS.

Blood pressure lowering effect of a pea protein hydrolysate in hypertensive rats and humans

The blood pressure lowering effect of a pea protein hydrolysate (PPH) that contained <3 kDa peptides, isolated by membrane ultrafiltration from the thermolysin digest of pea protein isolate (PPI), was examined using different rat models of hypertension as well as hypertensive human subjects. The PPH showed weak in vitro activities against renin and angiotensin converting enzyme (ACE) with inhibitory activities of 17 and 19%, respectively, at 1 mg/mL test concentration. Oral administration of the PPH to spontaneously hypertensive rats (SHR) at doses of 100 and 200 mg/kg body weight led to a lowering of hourly systolic blood pressure (SBP), with a maximum reduction of 19 mmHg at 4 h. In contrast, orally administered unhydrolyzed PPI had no blood pressure reducing effect in SHR, suggesting that thermolysin hydrolysis may have been responsible for releasing bioactive peptides from the native protein. Oral administration of the PPH to the Han:SPRD-cy rat (a model of chronic kidney disease) over an 8-week period led to 29 and 25 mmHg reductions in SBP and diastolic blood pressure, respectively. The PPH-fed rats had lower plasma levels of angiotensin II, the major vasopressor involved in development of hypertension, but there was no effect on plasma activity or renal mRNA levels of ACE. However, renal expression of renin mRNA levels was reduced by approximately 50% in the PPH-fed rats, suggesting that reduced renin may be responsible for the reduced levels of angiotensin II. In a 3-week randomized double blind placebo-controlled crossover human intervention trial (7 volunteers), significant (p<0.05) reductions (over placebo) in SBP of 5 and 6 mmHg were obtained in the second and third weeks, respectively, for the PPH group. Therefore, thermolysin derived bioactive peptides from PPH reduced blood pressure in hypertensive rats and human subjects, likely via effects on the renal angiotensin system.

Does angiotensin-converting enzyme polymorphism have association with symptomatic benign prostatic hyperplasia?

Objectives:

The aim of the study was to explore the putative significance of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and its correlation with the lower urinary tract symptoms (LUTS) in benign prostatic hyperplasia (BPH).

Materials and Methods:

ACE I/D polymorphisms were determined by polymerase chain reaction (PCR) in 200 patients with moderate to severe LUTS due to BPH and 200 patients of same age group without the LUTS having normal size prostate. ACE levels were estimated by spectrophotometer method. Logistic regression models were used to determine the genetic effects using SPSS statistical software (version 12.0).

Results and Conclusions:

The distribution of genotypes along with allelic frequency and carriage rate did not significantly differ between study and control groups. This study suggests that I/D polymorphisms within the ACE gene are not associated with the presence of LUTS in BPH patients. Future studies in large cohorts are needed that may reveal the spectrum of cellular mechanism mediated by ACE relevant to pathophysiology of BPH and effect of ethnic differences.

Pregnancy-associated homeostasis and dysregulation: lessons from genetically modified animal models

Physiological alterations occur in many organ systems during pregnancy. These changes are necessary for the adaptation to pregnancy-specific physiological processes in mother and fetus, and the placenta plays a critical role in the maintenance of homeostasis in pregnancy. Dysregulation of these functional feto-maternal interactions leads to severe complications. There have been many attempts to create animal models that mimic the hypertensive disorders of pregnancy, especially pre-eclampsia. In this review, we summarize the physiology of pregnancy and placental function, and discuss the placental gene expression in normal pregnancy. In addition, we assess a number of established animal models focusing on a specific pathogenic mechanism of pre-eclampsia, including genetically modified mouse models involving the renin-angiotensin system. Validation of these animal models would contribute significantly to understanding the basic principles of pregnancy-associated homeostasis and the pathogenesis of pre-eclampsia.

A polymorphism in ACE2 is associated with a lower risk for fatal cardiovascular events in females: the MORGAM project

Angiotensin II, a vasoconstrictor and the main effector molecule of the renin-angiotensin system, is known to influence inflammation, thrombosis, low-density lipoprotein oxidation and growth factors, all of which contribute to cardiovascular disease. The associations of polymorphisms in the angiotensin-converting enzyme 2 (ACE2) gene with cardiovascular risk have not been fully determined. Single nucleotide polymorphisms (SNPs) in ACE2 were genotyped in participants of the prospective MORGAM study (n = 5092) from five cohorts: ATBC, FINRISK, Northern Sweden, PRIME/Belfast and PRIME/France. Using a case-cohort design, associations were sought between SNPs and haplotypes with cardiovascular events during follow-up (Cox proportional hazards model). The comparison group were a subset of all MORGAM participants who were selected to ensure similar age and sex distributions among the cases and controls. The A allele of the rs2285666 SNP (HR = 0.3, p = 0.04) was significantly associated with the risk of cardiovascular death in female subjects. These findings complement those found in other studies of SNPs in the ACE2 gene in relation to cardiovascular disease risk. As females carry two copies of the ACE2 gene, and given its plausible biological role in cardiovascular disease risk, further studies of ACE2 should be prioritized.

Involvement of angiotensin II and reactive oxygen species in pancreatic fibrosis

BACKGROUND

Pancreatic cancers often develop in the context of pancreatic fibrosis caused by chronic pancreas inflammation, which also results in the accumulation of reactive oxygen species (ROS), pancreatic parenchymal cell death, and stellate cell activation. Angiotensin II, which is converted from angiotensin I by the angiotensin-converting enzyme (ACE), stimulates ROS production via NADPH oxidase. In stellate cells, angiotensin II activates the stress-activated protein kinase p38. However, the molecular mechanism by which angiotensin II regulates pancreatic inflammation and fibrosis remains to be determined.

METHODS

Wistar Bonn/Kobori (WBN/Kob) rats spontaneously develop chronic pancreatic inflammation. To examine whether blockade of the renin-angiotensin system affects the development of pancreatic fibrosis, WBN/Kob rats were given angiotensin II type 1 receptor (AT1R) blocker or ACE inhibitor (ACEI). Next, we assessed the role of angiotensin II and its possible downstream target p38α in stellate cell activation using primary stellate cells.

RESULTS

Treatment with AT1R blocker and ACEI prevented the development of chronic pancreatitis and fibrosis. In stellate cells, angiotensin II upregulated the expression of angiotensin II receptors, α-smooth muscle actin (SMA) and transforming growth factor-β. In addition, p38α was found to be essential to collagen type I production and α-SMA expression. ROS accumulation is enhanced in chronic pancreatic inflammation, which increases the risk of pancreatic cancer.

CONCLUSIONS

Inhibition of the angiotensin II signaling pathway might be a promising strategy to prevent pancreatic fibrogenesis and subsequent carcinogenesis.

Local bone marrow Renin-Angiotensin system and atherosclerosis

Local hematopoietic bone marrow (BM) renin-angiotensin system (RAS) affects the growth, production, proliferation differentiation, and function of hematopoietic cells. Angiotensin II (Ang II), the dominant effector peptide of the RAS, regulates cellular growth in a wide variety of tissues in pathobiological states. RAS, especially Ang II and Ang II type 1 receptor (AT1R), has considerable proinflammatory and proatherogenic effects on the vessel wall, causing progression of atherosclerosis. Recent investigations, by analyzing several BM chimeric mice whose BM cells were positive or negative for AT1R, disclosed that AT1R in BM cells participates in the pathogenesis of atherosclerosis. Therefore, AT1R blocking not only in vascular cells but also in the BM could be an important therapeutic approach to prevent atherosclerosis. The aim of this paper is to review the function of local BM RAS in the pathogenesis of atherosclerosis.

Plasma and tissue levels of proangiotensin-12 and components of the renin-angiotensin system (RAS) following low- or high-salt feeding in rats

The renin-angiotensin system (RAS) is an essential regulator of the blood pressure and body fluid balance, but the processing cascade or role of the tissue RAS remains obscure. Proangiotensin-12 (proang-12), a novel angiotensin peptide recently discovered in rat tissues, is assumed to function as a factor of the tissue RAS. To investigate the tissue production of proang-12, we measured the circulating and tissue components of the RAS including proang-12 following low-, normal-, or high-salt feeding in rats. Twelve-week-old male Wistar rats were fed a low-salt 0.3% NaCl or high-salt 8% NaCl diet for 7 days and compared with those fed a normal-salt diet of 0.7% NaCl. Low-salt feeding elevated the plasma renin activity and aldosterone concentration, resulting in significant increases in Ang I and Ang II levels in the plasma or kidney tissue, as compared with the normal- or high-salt group. Despite the increases in plasma renin activity, Ang I, and Ang II, the proang-12 levels in plasma and various tissues including the kidneys, small intestine, cardiac ventricles, and brain remained unchanged following low-salt feeding. These results suggest that peptide levels of proang-12 in rat plasma and tissues are regulated in a manner independent of the circulating RAS.

Confirmation That the Renin Gene Distal Enhancer Polymorphism REN -5312C/T Is Associated With Increased Blood Pressure

Background— Studies of knockout and transgenic mice have demonstrated key roles for genes encoding components of the renin angiotensin system in blood pressure regulation. However, whether polymorphisms in these genes contribute to the cause of essential hypertension in humans is still a matter of debate.

Methods and Results— We performed an experiment with dense tagging single-nucleotide polymorphism coverage of 4 genes encoding proteins that control the overall activity of the cascade, namely renin, angiotensinogen, angiotensin-converting enzyme, and angiotensin-converting enzyme 2, in 2 Irish populations. Both clinic and 24-hour ambulatory blood pressure measurements were available from population I (n=387), whereas just clinic blood pressure was measured in population II (n=1024). Of the 23 polymorphisms genotyped, only a single renin gene polymorphism, REN-5312C/T, showed consistent statistically significant associations with elevated diastolic pressures. Carriage of one REN-5312T allele was associated with the following age- and sex-adjusted increments in diastolic pressures (mean [95% CI]): population I, clinic, 1.5 mm Hg (0.3 to 2.8); daytime, 1.4 mm Hg (0.4 to 2.4); night-time, 1.3 mm Hg (0.4 to 2.3), and population II, clinic, 1.1 mm Hg (0.1 to 2.1). Haplotypic analyses and multivariate stepwise regression analyses were in concordance with individual single-nucleotide polymorphism analyses.

Conclusions— The REN-5312T allele had been shown previously to result in increased in vitro expression of the renin gene. We have now shown, in 2 independent populations, that carriage of a REN-5312T allele is associated with elevated diastolic blood pressure. These data provide evidence that renin is an important susceptibility gene for arterial hypertension in whites.

Interplay of tumor microenvironment cell types with parenchymal cells in pancreatic cancer development and therapeutic implications

INTRODUCTION

The process of "induction," namely, the formation of a tissue by the functional interaction between the epithelial layer and the stroma, is key for the development of many organs, in particular to the pancreas.

DISCUSSION

In diseases like pancreatic cancer, most studies performed to date, in the area of pancreatic cancer, have focused on studying epithelial cells and their contribution to this disease. Strikingly, until recently, the stroma that surrounds cancer cells in pancreatic tumors (desmoplastic reaction-tumor microenvironment) has remained an underrepresented area of research. However, several laboratories are increasingly posing questions as what is the role of this tumor microenvironment in the development and progression of this fatal disease. Therefore, in the current article, we define and describe the components of this desmoplastic reaction and the pancreatic tumor microenvironment and briefly review advances being made. More importantly, we highlight the urgent need of research in this field.

CONCLUSION

We anticipate that, because of the paucity of knowledge on this subject, studies on the pancreatic tumor microenvironment will bring new concepts which will ultimately impact in designing new diagnosis and treatment for this disease.

Prolonged clonidine treatment: catecholamines, renin activity and aldosterone following exercise in hypertensives

Eight patients with essential hypertension, WHO grade I-III, were studied under standardized conditions in a metabolic ward, before and after 8-20 weeks of treatment with clonidine in a maintenance dose of 300-600 micrograms/24 h. Before clonidine, plasma noradrenaline concentration (PNA), plasma adrenaline concentration (PA), plasma renin activity (PRA) and plasma aldosterone concentration (PAC) increased in response to standing and submaximal exercise for 20 min. PNA was positively correlated to pulse rate in the supine position (R = 0.74, p 0.05) and the increase in PNA to the increase in pulse rate during exercise (min 10, R=0.73, p less than 0.05; min 15, R = 0.79, p less than 0.05; min 20, R = 0.74, p less than 0.05). No other significant correlations were found between PNA, PA, PRA and PAC on the one hand and blood pressure (BP) and pulse rate on the other. Clonidine reduced BP, pulse rate, PNA and PRA under all conditions studied. PA was reduced in the upright position and in connection with exercise. PAC was reduced during clonidine after exercise but otherwise unaltered. The clonidine-induced decrease in PNA was positively correlated to the decrease in diastolic BP both in the supine (R = 0.76, p less than 0.05) and in the upright (R = 0.80, p less than 0.05) position. thus, long-term clonidine treatment lowered the BP and pulse rate, at least partly by reducing sympathetic activity via a central mechanism. However, clonidine did not block the sympathetic reflex mechanisms engaged in the maintenance of BP in the upright position. During clonidine, the adrenaline values were lower than before treatment in the supine and in the upright position and also following exercise, indicating that clonidine exerts an inhibitory effect on the sympatho-adreno-medullary system.

The influence of sar1 ala8 angiotensin II (saralasin) on plasma aldosterone in hypertensive patients

The effect of a 4-hour infusion of the angiotensin II analogue sar1 ala8 angiotensin II (saralasin) on plasma aldosterone concentration (PAC) was assessed in relation to plasma renin activity (PRA) in 12 patients, both on normal sodium intake and after marked sodium depletion. On normal sodium intake the response of PAC to saralasin was variable; following sodium depletion saralasin induced a marked decrease in PAC in 11 of 12 patients. The extent of the change in PAC induced by saralasin correlated closely with log PRA. The data indicate that saralasin is also a competitive antagonist of the effect of the endogenous renin-angiotensin system (RAS) on the adrenal cortex, with agonistic activity appearing at low levels of PRA. The effect of sodium depletion on AC appears to be mediated to a major degree by the RAS.

Angiotensin II in primary hypertension, relationship to plasma renin activity, aldosterone and urinary electrolytes

Plasma concentrations of angiotensin II (AII) were studied in 36 patients with primary (essential) hypertension and 15 normotensive control subjects during basal (1 h supine rest), upright and frusemide-stimulated (80 mg orally) conditions. Plasma renin activity (PRA) and plasma aldosterone (PA) were determined on the same occasions. AII was then correlated statistically to PRA, PA and 24-hour urinary excretions of aldosterone (Aldo-U), sodium and potassium and to the blood pressure (BP) levels. The AII values in the hypertensive patients were not statistically significantly different from those in the normotensive subjects. A close relationship was found between the AII values and the corresponding PRA values in the hypertensive patients (r=0.65--0.76, p less than 0.001 for all). Correlations between AII and PA, and AII and Aldo-U were not consistently significant. No correlation was found between AII and BP or between AII and 24-hour urinary electrolytes. The findings point to an intact function between PRA and AII but a disturbed AII-aldosterone interrelation in primary hypertension.

Hyponatremia in the acute stage after traumatic cervical spinal cord injury: clinical and neuroanatomic evidence for autonomic dysfunction

STUDY DESIGN

Retrospective cohort study supplemented by analysis of postmortem spinal cord tissue.

OBJECTIVES

This study examines the frequency of hyponatremia in early stage (2 weeks) after cervical spinal cord injury (SCI), and the relationship between integrity of key autonomic pathways and hyponatremia.

SUMMARY OF BACKGROUND DATA

Interruption of key circuits in the spinal cord can induce autonomic dysfunction with disordered metabolic and physiologic homeostasis. Given that hyponatremia may be a common electrolyte disorder during the acute stage post-SCI, we hypothesized that disconnection of descending sympathetic renal spinal cord tracts may be associated with hyponatremia after SCI.

METHODS

Consecutive individuals with cervical spine trauma were included in our cohort of patients, which was divided into a SCI group and a control group (patients with spine trauma without SCI). Also, postmortem spinal cord sections from individuals with cervical, motor complete SCI, and control cases without CNS trauma were evaluated regarding the extent of axonal preservation within the descending vasomotor pathways, the descending renal sympathetic pathways (DRSPs), the corticospinal tracts, and the dorsal columns.

RESULTS

There were 21 SCI individuals (6 women, 15 men; ages, 17-83 years; mean, 57.1) and 12 patients in the control spine trauma group who did not have SCI (4 women, 8 men; ages 18-90 years; mean, 45.9). Patients had either motor complete (7/21) or motor incomplete (14/21) tetraplegia. Hyponatremia occurred in 85.7% after SCI, which was significantly more frequent than the control group. Postmortem analysis included 5 control cases and 6 SCI individuals of whom 3 developed hyponatremia. The number of preserved axons within the DRSPs from normonatremic SCI patients was significantly lower than the number of axons within DRSPs from hyponatremic SCI patients, but development of hyponatremia was not associated with the integrity of the descending vasomotor pathways. Hyponatremic SCI individuals also showed greater evidence of neurogenic hypotension than normonatremic SCI individuals.

CONCLUSION

Hyponatremia is common in the early stage post-SCI. Our results also suggest that hyponatremia is associated with the integrity of descending renal sympathetic circuits which mediate the renin-angiotensin response to neural injury, in the setting of neurogenic hypotension with cardiovascular dysfunction.

Aliskiren: clinical experience and future perspectives of renin inhibition

BACKGROUND

Aliskiren, the first renin inhibitor with sufficient bioavailability for oral use, is now available to clinicians treating hypertension.

OBJECTIVE

The novel mechanism by which aliskiren works was used to provide understanding of its therapeutic and adverse effects.

METHODS

After reviewing physiology and preclinical studies, human studies of aliskiren in hypertension were reviewed. Effects of aliskiren on serum levels and enzymatic activity of renin were explored.

RESULTS/CONCLUSIONS

Aliskiren has antihypertensive efficacy similar to existing medications such as thiazide diuretics, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, and can be used in drug combinations. Preclinical studies indicate possible cardioprotective and renoprotective effects, similar to other inhibitors of the renin-angiotensin cascade, but future studies are needed in humans.

Role of bone marrow renin-angiotensin system in the pathogenesis of atherosclerosis

The renin-angiotensin system (RAS) has been considered to be a circulating hormonal system that regulates blood pressure, blood flow, fluid volume and electrolyte balance. A growing body of evidence indicates local effects of an activated RAS, particularly in the cardiac, vascular, and renal systems. It is now well established that RAS, especially angiotensin II (Ang II) and Ang II type 1 receptor (AT1R) pathway, has significant pro-inflammatory actions on the vessel wall, leading to progression of atherosclerosis. Recent reports suggest that an activated RAS has local effects in bone marrow (BM), which contributes to the regulation of normal and malignant hematologic processes. We reported that AT1aR in BM cells participate in the pathogenesis of atherosclerosis by analyzing several BM chimeric mice whose BM cells were positive or negative for AT1aR. These results suggest that blockade of AT1R not only in vascular cells but also in BM could be an important strategy to prevent atherosclerosis. In this review, we overview recent findings on a role of RAS in the pathogenesis of atherosclerosis, and discuss functional contribution of a local RAS in BM to progression and destabilization of atherosclerotic plaque.