Intracellular Calcium Dynamics in Primary Human Adrenocortical Cells Deciphered with a Novel Pipeline

INTRODUCTION

The fluctuations of the intracellular Ca2+ concentration ([Ca2+]i) are key physiological signals for cell function under normal conditions and can undergo profound alterations in disease states, as high blood pressure due to endocrine disorders like primary aldosteronism (PA). However, when assessing such fluctuations several parameters in the Ca2+ signal dynamics need to be considered, which renders their assessment challenging.

AIM

Aim to develop an observer-independent custom-made pipeline to analyze Ca2+ dynamics in terms of frequency and peak parameters, as amplitude, full width at half maximum (FWHM) and area under the curve (AUC).

METHODS

We applied a custom-made methodology to aldosterone-producing adenoma (APA) and APA adjacent cells (AAC) and found this pipeline to be suitable for monitoring and processing a wide-range of [Ca2+]i events in these cell types delivering reproducible results.

CONCLUSION

The designed pipeline can provide a useful tool for [Ca2+]i signal analysis that allows comparisons of Ca2+ dynamics not only in PA, but in other cell phenotypes that are relevant for the regulation of blood pressure.

Association of adrenal steroids with metabolomic profiles in patients with primary and endocrine hypertension

Introduction

Endocrine hypertension (EHT) due to pheochromocytoma/paraganglioma (PPGL), Cushing's syndrome (CS), or primary aldosteronism (PA) is linked to a variety of metabolic alterations and comorbidities. Accordingly, patients with EHT and primary hypertension (PHT) are characterized by distinct metabolic profiles. However, it remains unclear whether the metabolomic differences relate solely to the disease-defining hormonal parameters. Therefore, our objective was to study the association of disease defining hormonal excess and concomitant adrenal steroids with metabolomic alterations in patients with EHT.

Methods

Retrospective European multicenter study of 263 patients (mean age 49 years, 50% females; 58 PHT, 69 PPGL, 37 CS, 99 PA) in whom targeted metabolomic and adrenal steroid profiling was available. The association of 13 adrenal steroids with differences in 79 metabolites between PPGL, CS, PA and PHT was examined after correction for age, sex, BMI, and presence of diabetes mellitus.

Results

After adjustment for BMI and diabetes mellitus significant association between adrenal steroids and metabolites - 18 in PPGL, 15 in CS, and 23 in PA - were revealed. In PPGL, the majority of metabolite associations were linked to catecholamine excess, whereas in PA, only one metabolite was associated with aldosterone. In contrast, cortisone (16 metabolites), cortisol (6 metabolites), and DHEA (8 metabolites) had the highest number of associated metabolites in PA. In CS, 18-hydroxycortisol significantly influenced 5 metabolites, cortisol affected 4, and cortisone, 11-deoxycortisol, and DHEA each were linked to 3 metabolites.

Discussions

Our study indicates cortisol, cortisone, and catecholamine excess are significantly associated with metabolomic variances in EHT versus PHT patients. Notably, catecholamine excess is key to PPGL's metabolomic changes, whereas in PA, other non-defining adrenal steroids mainly account for metabolomic differences. In CS, cortisol, alongside other non-defining adrenal hormones, contributes to these differences, suggesting that metabolic disorders and cardiovascular morbidity in these conditions could also be affected by various adrenal steroids.

Increased Soluble Interleukin 6 Receptors in Fabry Disease

Fabry disease (FD) is an X-linked lysosome storage disease that results in the accumulation of globotriaosylceramide (Gb3) throughout the body leading to irreversible target organ damage. As the role of secondary mediators (inflammatory molecules) and their mechanisms has not been fully elucidated, we focused on the interleukin (IL)-6 system in adult FD patients and in matched healthy subjects. To obtain insights into the complex regulation of IL-6 actions, we used a novel approach that integrates information from plasma and exosomes of FD patients (n = 20) and of healthy controls (n = 15). Soluble IL-6 receptor (sIL-6R) levels were measured in plasma with the ELISA method, and membrane-bound IL-6R was quantified in plasma and urinary exosomes using flow cytometry. In FD patients, the levels of soluble IL-6R in plasma were higher than in control subjects (28.0 ± 5.4 ng/mL vs. 18.9 ± 5.4 ng/mL, p < 0.0001); they were also higher in FD subjects with the classical form as compared to those with the late-onset form of the disease (36.0 ± 11.4 ng/mL vs. 26.1 ± 4.5 ng/mL, p < 0.0001). The percentage of urinary exosomes positive for IL-6R was slightly lower in FD (97 ± 1 vs. 100 ± 0% of events positive for IL-6R, p < 0.05); plasma IL-6 levels were not increased. These results suggest a potential role of IL-6 in triggering the inflammatory response in FD. As in FD patients only the levels of sIL-6Rs are consistently higher than in healthy controls, the IL-6 pathogenic signal seems to prevail over the homeostatic one, suggesting a potential mechanism causing multi-systemic damage in FD.

Primary Aldosteronism and Drug Resistant Hypertension: A "Chicken-Egg" Story

Drug-resistant arterial hypertension (RH) is a major risk factor for cardiovascular disease, often due to overlooked underlying causes. Identification of such causes poses significant clinical challenges. In this setting, primary aldosteronism (PA) is a frequent cause of RH and its prevalence in RH patients is likely higher than 20%.The pathophysiological link between PA and the development and maintenance of RH involves target organ damage and the cellular and extracellular effects of aldosterone excess that promote pro-inflammatory and pro-fibrotic changes in the kidney and vasculature.The feasibility of adrenal vein sampling in PA patients with RH, and the clinical benefit achieved by adrenalectomy, further emphasize the need to implement systematic screening for this common form of secondary hypertension in the management of a high-risk population as RH patients.: We herein review the current knowledge of the factors that contribute to the RH phenotype with a focus on PA and discuss the issues regarding the screening for PA in this setting and the therapeutic approaches (surgical and medical) aimed at resolving RH caused by PA.

Understanding the Pathogenesis of Cardiac Complications in Patients with Propionic Acidemia and Exploring Therapeutic Alternatives for Those Who Are Not Eligible or Are Waiting for Liver Transplantation

The guidelines for the management of patients affected by propionic acidemia (PA) recommend standard cardiac therapy in the presence of cardiac complications. A recent revision questioned the impact of high doses of coenzyme Q10 on cardiac function in patients with cardiomyopathy (CM). Liver transplantation is a therapeutic option for several patients since it may stabilize or reverse CM. Both the patients waiting for liver transplantation and, even more, the ones not eligible for transplant programs urgently need therapies to improve cardiac function. To this aim, the identification of the pathogenetic mechanisms represents a key point. Aims: This review summarizes: (1) the current knowledge of the pathogenetic mechanisms underlying cardiac complications in PA and (2) the available and potential pharmacological options for the prevention or the treatment of cardiac complications in PA. To select articles, we searched the electronic database PubMed using the Mesh terms "propionic acidemia" OR "propionate" AND "cardiomyopathy" OR "Long QT syndrome". We selected 77 studies, enlightening 12 potential disease-specific or non-disease-specific pathogenetic mechanisms, namely: impaired substrate delivery to TCA cycle and TCA dysfunction, secondary mitochondrial electron transport chain dysfunction and oxidative stress, coenzyme Q10 deficiency, metabolic reprogramming, carnitine deficiency, cardiac excitation-contraction coupling alteration, genetics, epigenetics, microRNAs, micronutrients deficiencies, renin-angiotensin-aldosterone system activation, and increased sympathetic activation. We provide a critical discussion of the related therapeutic options. Current literature supports the involvement of multiple cellular pathways in cardiac complications of PA, indicating the growing complexity of their pathophysiology. Elucidating the mechanisms responsible for such abnormalities is essential to identify therapeutic strategies going beyond the correction of the enzymatic defect rather than engaging the dysregulated mechanisms. Although these approaches are not expected to be resolutive, they may improve the quality of life and slow the disease progression. Available pharmacological options are limited and tested in small cohorts. Indeed, a multicenter approach is mandatory to strengthen the efficacy of therapeutic options.

Gastrointestinal Manifestations and Low-FODMAP Protocol in a Cohort of Fabry Disease Adult Patients

Fabry disease (FD) is an X-linked lysosomal disorder caused by α-galactosidase A enzyme deficiency. Gastrointestinal (GI) manifestations are reported in FD with a prevalence of about 50%, usually treated by Enzymatic Replacement Therapy (ERT) or oral treatment. Since FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) can be involved in GI manifestations and dysbiosis in FD patients, a low-FODMAP diet could represent an alternative adjunctive treatment in FD subjects, as well as being useful for reducing symptoms in Irritable Bowel Syndrome (IBS). We retrospectively assessed data from 36 adult FD patients followed at the Inherited Metabolic Rare Diseases Adult Centre of the University Hospital of Padova (mean age 47.6 ± 16.2 years). Patients were screened for GI symptoms by IBS severity score and Gastrointestinal Symptom Rating Scale (GSRS) questionnaires. In symptomatic patients, the low-FODMAP diet was proposed in order to improve GI manifestations; it consists of a phase of elimination of fermentable saccharides, succeeded by a gradual reintegration of the same. Severe or moderate GI symptoms were found in 61.1% of patients, with no correlation to the therapy in use, and significantly more severe in the classical form of FD. The protocol was completed by seven patients affected by severe GI manifestations, significantly higher than the others. The low-FODMAP diet significantly improved indigestion, diarrhoea, and constipation. This dietetic protocol seemed to have a positive impact on intestinal symptoms, by identifying and reducing the intake of the foods most related to the onset of disorders and improving the clinical manifestations. A low-FODMAP diet may be an effective alternative approach to improve intestinal manifestations and quality of life, and nutrition can play an important role in the multidisciplinary care of patients with FD.

Urine-Derived Epithelial Cells as a New Model to Study Renal Metabolic Phenotypes of Patients with Glycogen Storage Disease 1a

Glycogen storage diseases (GSDs) represent a model of pathological accumulation of glycogen disease in the kidney that, in animal models, results in nephropathy due to abnormal autophagy and mitochondrial function. Patients with Glycogen Storage Disease 1a (GSD1a) accumulate glycogen in the kidneys and suffer a disease resembling diabetic nephropathy that can progress to renal failure. In this study, we addressed whether urine-derived epithelial cells (URECs) from patients with GSD1a maintain their biological features, and whether they can be used as a model to study the renal and metabolic phenotypes of this genetic condition. Studies were performed on cells extracted from urine samples of GSD1a and healthy subjects. URECs were characterized after the fourth passage by transmission electron microscopy and immunofluorescence. Reactive oxygen species (ROS), at different glucose concentrations, were measured by fluorescent staining. We cultured URECs from three patients with GSD1a and three healthy controls. At the fourth passage, URECs from GSD1a patients maintained their massive glycogen content. GSD1a and control cells showed the ciliary structures of renal tubular epithelium and the expression of epithelial (E-cadherin) and renal tubular cells (aquaporin 1 and 2) markers. Moreover, URECs from both groups responded to changes in glucose concentrations by modulating ROS levels. GSD1a cells were featured by a specific response to the low glucose stimulus, which is the condition that more resembles the metabolic derangement of patients with GSD1a. Through this study, we demonstrated that URECs might represent a promising experimental model to study the molecular mechanisms leading to renal damage in GSD1a, due to pathological glycogen storage.

Peptidergic G Protein-Coupled Receptor Regulation of Adrenal Function: Bench to Bedside and Back

An altered secretion of adrenocortical and adrenomedullary hormones plays a role in the clinical syndromes of primary aldosteronism (PA), Cushing, and pheochromocytoma. Moreover, an altered production of adrenocortical hormones and/or an abnormal release of factors by the adrenal medulla are involved in several other diseases, including high blood pressure, congestive heart failure, liver cirrhosis, nephrotic syndrome, primary reninism, renovascular hypertension, Addison disease, Bartter, Gitelman, and virilization syndromes. Understanding the regulation of adrenal function and the interactions between adrenal cortex and medulla is, therefore, the prerequisite for mechanistic understanding of these disorders. Accumulating evidence indicates that the modulation of adrenal hormone biosynthesis is a process far more complex than originally thought, as it involves several factors, each cooperating with the other. Moreover, the tight vascular and neural interconnections between the adrenal cortex and medulla underlie physiologically relevant autocrine/paracrine interactions involving several peptides. Besides playing a pathophysiological role in common adrenal diseases, these complex mechanisms could intervene also in rare diseases, such as pheochromocytoma concomitant with adrenal Cushing or with PA, and PA co-occurring with Cushing, through mechanisms that remain to be fully understood at the molecular levels. Heterodimerization of G protein-coupled receptors (GPCRs) induced by peptide signaling is a further emerging new modulatory mechanism capable of finely tuning adrenal hormones synthesis and release. In this review we will examine current knowledge on the role of peptides that act via GPCRs in the regulation of adrenal hormone secretion with a particular focus on autocrine-paracrine signals.

Whole blood methylome-derived features to discriminate endocrine hypertension

Background

Arterial hypertension represents a worldwide health burden and a major risk factor for cardiovascular morbidity and mortality. Hypertension can be primary (primary hypertension, PHT), or secondary to endocrine disorders (endocrine hypertension, EHT), such as Cushing's syndrome (CS), primary aldosteronism (PA), and pheochromocytoma/paraganglioma (PPGL). Diagnosis of EHT is currently based on hormone assays. Efficient detection remains challenging, but is crucial to properly orientate patients for diagnostic confirmation and specific treatment. More accurate biomarkers would help in the diagnostic pathway. We hypothesized that each type of endocrine hypertension could be associated with a specific blood DNA methylation signature, which could be used for disease discrimination. To identify such markers, we aimed at exploring the methylome profiles in a cohort of 255 patients with hypertension, either PHT (n = 42) or EHT (n = 213), and at identifying specific discriminating signatures using machine learning approaches.

Results

Unsupervised classification of samples showed discrimination of PHT from EHT. CS patients clustered separately from all other patients, whereas PA and PPGL showed an overall overlap. Global methylation was decreased in the CS group compared to PHT. Supervised comparison with PHT identified differentially methylated CpG sites for each type of endocrine hypertension, showing a diffuse genomic location. Among the most differentially methylated genes, FKBP5 was identified in the CS group. Using four different machine learning methods—Lasso (Least Absolute Shrinkage and Selection Operator), Logistic Regression, Random Forest, and Support Vector Machine—predictive models for each type of endocrine hypertension were built on training cohorts (80% of samples for each hypertension type) and estimated on validation cohorts (20% of samples for each hypertension type). Balanced accuracies ranged from 0.55 to 0.74 for predicting EHT, 0.85 to 0.95 for predicting CS, 0.66 to 0.88 for predicting PA, and 0.70 to 0.83 for predicting PPGL.

Conclusions

The blood DNA methylome can discriminate endocrine hypertension, with methylation signatures for each type of endocrine disorder.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01347-y.

Machine learning for classification of hypertension subtypes using multi-omics: A multi-centre, retrospective, data-driven study

Background

Arterial hypertension is a major cardiovascular risk factor. Identification of secondary hypertension in its various forms is key to preventing and targeting treatment of cardiovascular complications. Simplified diagnostic tests are urgently required to distinguish primary and secondary hypertension to address the current underdiagnosis of the latter.

Methods

This study uses Machine Learning (ML) to classify subtypes of endocrine hypertension (EHT) in a large cohort of hypertensive patients using multidimensional omics analysis of plasma and urine samples. We measured 409 multi-omics (MOmics) features including plasma miRNAs (PmiRNA: 173), plasma catechol O-methylated metabolites (PMetas: 4), plasma steroids (PSteroids: 16), urinary steroid metabolites (USteroids: 27), and plasma small metabolites (PSmallMB: 189) in primary hypertension (PHT) patients, EHT patients with either primary aldosteronism (PA), pheochromocytoma/functional paraganglioma (PPGL) or Cushing syndrome (CS) and normotensive volunteers (NV). Biomarker discovery involved selection of disease combination, outlier handling, feature reduction, 8 ML classifiers, class balancing and consideration of different age- and sex-based scenarios. Classifications were evaluated using balanced accuracy, sensitivity, specificity, AUC, F1, and Kappa score.

Findings

Complete clinical and biological datasets were generated from 307 subjects (PA=113, PPGL=88, CS=41 and PHT=112). The random forest classifier provided ∼92% balanced accuracy (∼11% improvement on the best mono-omics classifier), with 96% specificity and 0.95 AUC to distinguish one of the four conditions in multi-class ALL-ALL comparisons (PPGL vs PA vs CS vs PHT) on an unseen test set, using 57 MOmics features. For discrimination of EHT (PA + PPGL + CS) vs PHT, the simple logistic classifier achieved 0.96 AUC with 90% sensitivity, and ∼86% specificity, using 37 MOmics features. One PmiRNA (hsa-miR-15a-5p) and two PSmallMB (C9 and PC ae C38:1) features were found to be most discriminating for all disease combinations. Overall, the MOmics-based classifiers were able to provide better classification performance in comparison to mono-omics classifiers.

Interpretation

We have developed a ML pipeline to distinguish different EHT subtypes from PHT using multi-omics data. This innovative approach to stratification is an advancement towards the development of a diagnostic tool for EHT patients, significantly increasing testing throughput and accelerating administration of appropriate treatment.

Funding

European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 633983, Clinical Research Priority Program of the University of Zurich for the CRPP HYRENE (to Z.E. and F.B.), and Deutsche Forschungsgemeinschaft (CRC/Transregio 205/1).

Identification of risk loci for primary aldosteronism in genome-wide association studies

Primary aldosteronism affects up to 10% of hypertensive patients and is responsible for treatment resistance and increased cardiovascular risk. Here we perform a genome-wide association study in a discovery cohort of 562 cases and 950 controls and identify three main loci on chromosomes 1, 13 and X; associations on chromosome 1 and 13 are replicated in a second cohort and confirmed by a meta-analysis involving 1162 cases and 3296 controls. The association on chromosome 13 is specific to men and stronger in bilateral adrenal hyperplasia than aldosterone producing adenoma. Candidate genes located within the two loci, CASZ1 and RXFP2, are expressed in human and mouse adrenals in different cell clusters. Their overexpression in adrenocortical cells suppresses mineralocorticoid output under basal and stimulated conditions, without affecting cortisol biosynthesis. Our study identifies the first risk loci for primary aldosteronism and highlights new mechanisms for the development of aldosterone excess.

Preanalytical Considerations and Outpatient Versus Inpatient Tests of Plasma Metanephrines to Diagnose Pheochromocytoma

CONTEXT

Sampling of blood in the supine position for diagnosis of pheochromocytoma and paraganglioma (PPGL) results in lower rates of false positives for plasma normetanephrine than seated sampling. It is unclear how inpatient vs outpatient testing and other preanalytical factors impact false positives.

OBJECTIVE

We aimed to identify preanalytical precautions to minimize false-positive results for plasma metanephrines.

METHODS

Impacts of different blood sampling conditions on plasma metanephrines were evaluated, including outpatient vs inpatient testing, sampling of blood in semi- vs fully recumbent positions, use of cannulae vs direct venipuncture, and differences in outside temperature. A total of 3147 patients at 10 tertiary referral centers were tested for PPGL, including 278 with and 2869 without tumors. Rates of false-positive results were analyzed.

RESULTS

Outpatient rather than inpatient sampling resulted in 44% higher plasma concentrations and a 3.4-fold increase in false-positive results for normetanephrine. Low temperature, a semi-recumbent position, and direct venipuncture also resulted in significantly higher plasma concentrations and rates of false-positive results for plasma normetanephrine than alternative sampling conditions, although with less impact than outpatient sampling. Higher concentrations and rates of false-positive results for plasma normetanephrine with low compared with warm temperatures were only apparent for outpatient sampling. Preanalytical factors were without impact on plasma metanephrines in patients with PPGL.

CONCLUSION

Although inpatient blood sampling is largely impractical for screening patients with suspected PPGL, other preanalytical precautions (eg, cannulae, warm testing conditions) may be useful. Inpatient sampling may be reserved for follow-up of patients with difficult to distinguish true- from false-positive results.

Preanalytical Pitfalls in Untargeted Plasma Nuclear Magnetic Resonance Metabolomics of Endocrine Hypertension

Despite considerable morbidity and mortality, numerous cases of endocrine hypertension (EHT) forms, including primary aldosteronism (PA), pheochromocytoma and functional paraganglioma (PPGL), and Cushing’s syndrome (CS), remain undetected. We aimed to establish signatures for the different forms of EHT, investigate potentially confounding effects and establish unbiased disease biomarkers. Plasma samples were obtained from 13 biobanks across seven countries and analyzed using untargeted NMR metabolomics. We compared unstratified samples of 106 PHT patients to 231 EHT patients, including 104 PA, 94 PPGL and 33 CS patients. Spectra were subjected to a multivariate statistical comparison of PHT to EHT forms and the associated signatures were obtained. Three approaches were applied to investigate and correct confounding effects. Though we found signatures that could separate PHT from EHT forms, there were also key similarities with the signatures of sample center of origin and sample age. The study design restricted the applicability of the corrections employed. With the samples that were available, no biomarkers for PHT vs. EHT could be identified. The complexity of the confounding effects, evidenced by their robustness to correction approaches, highlighted the need for a consensus on how to deal with variabilities probably attributed to preanalytical factors in retrospective, multicenter metabolomics studies.

Genetic Diagnosis in a Cohort of Adult Patients with Inherited Metabolic Diseases: A Single-Center Experience

Inherited metabolic diseases (IMDs) are genetic conditions that result in metabolism alterations. Although research-based Next Generation Sequencing (NGS) testing for IMD has been recently implemented, its application in a clinical diagnostic setting remains challenging. Thus, we aimed at investigating the genetic diagnostic approach in a cohort of adult patients with IMDs referred to our adult metabolic unit. A retrospective analysis was performed collecting demographic, clinical, and genetic data of patients referred to the Adult Metabolic Unit in Padua from November 2017 to March 2022. In total, 108 adult patients (mean age: 33 years ± 17, 55% women) were enrolled in the study, and 83 (77%) of the patients transitioned from the pediatric metabolic clinics. The most prevalent groups of IMDs were disorders of complex molecule degradation (32 patients) and disorders of amino acid metabolism (31) followed by disorders of carbohydrates (26). Molecular genetic diagnosis was reported by 69 (64%) patients, with the higher rate reported by patients referred from specialty other than pediatric (88% vs. 55%). Almost all the subjects (92%) with disorders of complex molecule degradation had a genetic diagnosis. Patients with disorders of amino acid metabolism and disorders of carbohydrates had almost the same rate of genetic test (39% and 38%, respectively). Among the patients without a genetic diagnosis that we tested, two novel mutations in disease-associated genes were detected. In our single-center cohort, a consistent proportion (36%) of subjects with IMDs reaches the adulthood without a genetic demonstration of the disease. This lack, even if in some cases could be related to disease-specific diagnostic approach or to different disease onset, could be detrimental to patient management and impact to some of the specific needs of adult subjects.

Anthropometrics, Dietary Intake and Body Composition in Urea Cycle Disorders and Branched Chain Organic Acidemias: A Case Study of 18 Adults on Low-Protein Diets

Low-protein diets (LPDs) are the mainstream treatment for inborn errors of intermediary protein metabolism (IEIPM), but dietary management differs worldwide. Most studies have investigated pediatric populations and their goals such as growth and metabolic balance, showing a tendency toward increasing overweight and obesity. Only a few studies have examined nutritional status and dietary intake of adult IEIPM patients on LPDs. We assessed nutritional parameters (dietary intake using a 7-day food diary record, body composition by bioimpedance analysis, and biochemical serum values) in a group of 18 adult patients with urea cycle disorders (UCDs) and branched chain organic acidemia (BCOA). Mean total protein intake was 0.61 ± 0.2 g/kg/day (73.5% of WHO Safe Levels) and mean natural protein (PN) intake was 0.54 ± 0.2 g/kg/day; 33.3% of patients consumed amino acid (AA) supplements. A totally of 39% of individuals presented a body mass index (BMI) > 25 kg/m2 and patients on AA supplements had a mean BMI indicative of overweight. All patients reported low physical activity levels. Total energy intake was 24.2 ± 5 kcal/kg/day, representing 72.1% of mean total energy expenditure estimated by predictive formulas. The protein energy ratio (P:E) was, on average, 2.22 g/100 kcal/day. Plasmatic levels of albumin, amino acids, and lipid profiles exhibited normal ranges. Phase angle (PA) was, on average, 6.0° ± 0.9°. Fat mass percentage (FM%) was 22% ± 9% in men and 36% ± 4% in women. FM% was inversely and significantly related to total and natural protein intake. Data from IEIPM adults on LPDs confirmed the pediatric trend of increasing overweight and obesity despite a low energy intake. A low protein intake may contribute to an increased fat mass. Nutritional parameters and a healthy lifestyle should be routinely assessed in order to optimize nutritional status and possibly reduce risk of cardiovascular degenerative diseases in adult UCD and BCOA patients on LPDs.

A novel MRPS34 gene mutation with combined OXPHOS deficiency in an adult patient with Leigh syndrome

We report a novel pathogenic variant (c.223G > C; p.Gly75Arg) in the gene encoding the small mitoribosomal subunit protein mS34 in a long-surviving patient with Leigh Syndrome who was genetically diagnosed at age 34 years. The patient presented with delayed motor milestones and a stepwise motor deterioration during life, along with brain MRI alterations involving the subcortical white matter, deep grey nuclei and in particular the internal globi pallidi, that appeared calcified on CT scan. The novel variant is associated with a reduction of mS34 protein levels and of the OXPHOS complex I and IV subunits in peripheral blood mononuclear cells of the case. This study expands the number of variants that, by affecting the stability of the mitoribosome, may cause an OXPHOS deficiency in Leigh Syndrome and reports, for the first time, an unusual long survival in a patient with a homozygous MRPS34 pathogenic variant.

High prolactin levels in dihydropteridine reductase deficiency: A sign of therapy failure or additional pathology?

We report the case of a 22-year-old man with a diagnosis of dihydropteridine reductase (DHPR) deficiency who progressively developed movement disorders and epilepsy. Despite L-Dopa supplementation the patient continued to show high prolactin levels, with a discrepancy between the neurological clinical picture and the hormonal biochemical levels. For this reason, other potential causes were ruled out by performing a cerebral magnetic resonance imaging, which demonstrated a solid lesion in the pituitary gland strongly suggestive of a prolactinoma. As the association between metabolic disorders affecting biogenic amine synthesis and prolactinoma has not been previously reported in humans, this report suggests that a critical evaluation of the use of prolactin as a guide for therapy dosage should be made in patients with DHPR deficiency disorders.

Aldosterone and cortisol synthesis regulation by angiotensin-(1-7) and angiotensin-converting enzyme 2 in the human adrenal cortex

OBJECTIVE

The branch of the renin--angiotensin system constituting angiotensin-(1-7) [Ang-(1-7)], the Ang II type 2 receptor, the Mas receptors and the Ang-(1-7)-forming enzyme ACE-2, by counteracting the Ang II type 1 receptor (AT1R)-mediated effects, are held to be cardiovascular protective in several conditions. However, whether Ang-(1-7) and ACE-2 are detectable in human adrenocortical tissues and whether they affect aldosterone and cortisol biosynthesis was unknown.

METHODS

We measured angiotensin peptides with liquid chromatography tandem-mass spectrometry and ACE-2 mRNA with digital droplet (dd)PCR in human aldosterone-producing adenoma (APA) and APA-adjacent tissue obtained from patients with primary aldosteronism. We also investigated the effects of Ang-(1-7) and the ACE-2 activator diminazene aceturate (DIZE) on aldosterone synthase (CYP11B2) and 11β-hydroxylase (CYP11B1) gene expression, in the absence or presence of the AT1R antagonist irbesartan, or of the MasR antagonist A779.

RESULTS

APA and APA-adjacent adrenocortical tissues express ACE-2 mRNA and contain detectable amounts of Ang II and Ang-(2-8), but not of Ang I, Ang-(1-5), Ang (3-8) and Ang-(1-7). Under unstimulated and Ang II- stimulated conditions Ang-(1-7) did not blunt CYP11B1 and CYP11B2 mRNA. At supraphysiological concentrations (10-4 mol/l), Ang-(1-7) stimulated both CYP11B1 and CYP11B2 mRNA via the AT1R. The ACE-2 activator DIZE increased by 1.5-fold ACE-2 mRNA but did not blunt Ang II- upregulated CYP11B1 and CYP11B2 expression.

CONCLUSION

These results do not support the hypothesis that the ACE-2/Ang-(1-7)/MasR axis play a protective role by counteracting enhanced aldosterone secretion in humans.

Angiotensin peptides in the regulation of adrenal cortical function

The adrenal cortex plays a key role in the regulation of metabolism, salt and water homeostasis and sex differentiation by synthesizing glucocorticoid, mineralocorticoid and androgen hormones. Evidence exists that angiotensin II regulates adrenocortical function and it has been contended that angiotensin peptides of the non-canonical branch of the renin angiotensin system (RAS) might also modulate steroidogenesis in adrenals. Thus, the aim of this review is to examine the role of the RAS, and particularly of the angiotensin peptides and their receptors, in the regulation of adrenocortical hormones with particular focus on aldosterone production.

High sodium intake, glomerular hyperfiltration, and protein catabolism in patients with essential hypertension

AIMS

A blood pressure (BP)-independent metabolic shift towards a catabolic state upon high sodium (Na+) diet, ultimately favouring body fluid preservation, has recently been described in pre-clinical controlled settings. We sought to investigate the real-life impact of high Na+ intake on measures of renal Na+/water handling and metabolic signatures, as surrogates for cardiovascular risk, in hypertensive patients.

METHODS AND RESULTS

We analysed clinical and biochemical data from 766 consecutive patients with essential hypertension, collected at the time of screening for secondary causes. The systematic screening protocol included 24 h urine (24 h-u-) collection on usual diet and avoidance of renin-angiotensin-aldosterone system-confounding medications. Urinary 24 h-Na+ excretion, used to define classes of Na+ intake (low ≤2.3 g/day; medium 2.3-5 g/day; high >5 g/day), was an independent predictor of glomerular filtration rate after correction for age, sex, BP, BMI, aldosterone, and potassium excretion [P = 0.001; low: 94.1 (69.9-118.8) vs. high: 127.5 (108.3-147.8) mL/min/1.73 m2]. Renal Na+ and water handling diverged, with higher fractional excretion of Na+ and lower fractional excretion of water in those with evidence of high Na+ intake [FENa: low 0.39% (0.30-0.47) vs. high 0.81% (0.73-0.98), P < 0.001; FEwater: low 1.13% (0.73-1.72) vs. high 0.89% (0.69-1.12), P = 0.015]. Despite higher FENa, these patients showed higher absolute 24 h Na+ reabsorption and higher associated tubular energy expenditure, estimated by tubular Na+/ATP stoichiometry, accordingly [Δhigh-low = 18 (12-24) kcal/day, P < 0.001]. At non-targeted liquid chromatography/mass spectrometry plasma metabolomics in an unselected subcohort (n = 67), metabolites which were more abundant in high versus low Na+ intake (P < 0.05) mostly entailed intermediates or end products of protein catabolism/urea cycle.

CONCLUSION

When exposed to high Na+ intake, kidneys dissociate Na+ and water handling. In hypertensive patients, this comes at the cost of higher glomerular filtration rate, increased tubular energy expenditure, and protein catabolism from endogenous (muscle) or excess exogenous (dietary) sources. Glomerular hyperfiltration and the metabolic shift may have broad implications on global cardiovascular risk independent of BP.

Targeted Metabolomics as a Tool in Discriminating Endocrine From Primary Hypertension

CONTEXT

Identification of patients with endocrine forms of hypertension (EHT) (primary hyperaldosteronism [PA], pheochromocytoma/paraganglioma [PPGL], and Cushing syndrome [CS]) provides the basis to implement individualized therapeutic strategies. Targeted metabolomics (TM) have revealed promising results in profiling cardiovascular diseases and endocrine conditions associated with hypertension.

OBJECTIVE

Use TM to identify distinct metabolic patterns between primary hypertension (PHT) and EHT and test its discriminating ability.

METHODS

Retrospective analyses of PHT and EHT patients from a European multicenter study (ENSAT-HT). TM was performed on stored blood samples using liquid chromatography mass spectrometry. To identify discriminating metabolites a "classical approach" (CA) (performing a series of univariate and multivariate analyses) and a "machine learning approach" (MLA) (using random forest) were used.The study included 282 adult patients (52% female; mean age 49 years) with proven PHT (n = 59) and EHT (n = 223 with 40 CS, 107 PA, and 76 PPGL), respectively.

RESULTS

From 155 metabolites eligible for statistical analyses, 31 were identified discriminating between PHT and EHT using the CA and 27 using the MLA, of which 16 metabolites (C9, C16, C16:1, C18:1, C18:2, arginine, aspartate, glutamate, ornithine, spermidine, lysoPCaC16:0, lysoPCaC20:4, lysoPCaC24:0, PCaeC42:0, SM C18:1, SM C20:2) were found by both approaches. The receiver operating characteristic curve built on the top 15 metabolites from the CA provided an area under the curve (AUC) of 0.86, which was similar to the performance of the 15 metabolites from MLA (AUC 0.83).

CONCLUSION

TM identifies distinct metabolic pattern between PHT and EHT providing promising discriminating performance.

Drug-resistant hypertension in primary aldosteronism patients undergoing adrenal vein sampling: the AVIS-2-RH study

AIMS

We aimed at determining the rate of drug-resistant arterial hypertension in patients with an unambiguous diagnosis of primary aldosteronism (PA). Moreover, we sought for investigating the diagnostic performance of adrenal vein sampling (AVS), and the effect of adrenalectomy on blood pressure (BP) and prior treatment resistance in PA patients subtyped by AVS in major referral centres.

METHODS AND RESULTS

The Adrenal Vein Sampling International Study-2 (AVIS-2) was a multicentre international study that recruited consecutive PA patients submitted to AVS, according to current guidelines, during 15 years. The patients were over 18 years old with arterial hypertension and had an unambiguous diagnosis of PA. The rate of resistant hypertension was assessed at baseline and after adrenalectomy using the American Heart Association (AHA) 2018 definition. Information on presence or absence of resistant hypertension was available in 89% of the 1625 enrolled PA patients. Based on the AHA 2018 criteria, resistant hypertension was found in 20% of patients, of which about two-thirds (14%) were men and one-third (6%) women (χ2 = 17.1, P < 1*10-4) with a higher rate of RH in men than in women (23% vs. 15% P < 1*10-4). Of the 292 patients with resistant hypertension, 98 (34%) underwent unilateral AVS-guided adrenalectomy, which resolved BP resistance to antihypertensive treatment in all.

CONCLUSIONS

(i) Resistant hypertension is a common presentation in patients seeking surgical cure of PA; (ii) AVS is key for the optimal management of patients with PA due to resistant hypertension; and (iii) AVS-guided adrenalectomy allowed resolution of treatment-resistant hypertension.

Familial hyperaldosteronism type 1 and pregnancy: successful treatment with low dose dexamethasone

PURPOSE

Familial hyperaldosteronism type 1 (FH-1) is an autosomal dominant form of primary aldosteronism (PA), featuring a marked phenotypic heterogeneity, ranging from mild forms of PA and arterial hypertension (HT) to severe forms complicated by stroke at a young age. Affected patients usually reach the fertile age; hence, transmission of the disease to offspring is common. Notwithstanding this, only anecdotal reports of FH-1 in pregnancy exist and recommendations for treatment remain vague.

MATERIALS AND METHODS AND RESULTS

We herein report on a novel FH-1 pedigree featuring very severe HT, fatal aortic dissection, and high rate of early stroke, where a young FH-1 woman was successfully managed throughout pregnancy with low-dose dexamethasone.

CONCLUSIONS

Based on this experience and on available information on pathophysiology of FH-1 in pregnancy, the pros and cons of dexamethasone administration in the treatment of FH-1 in pregnancy are also discussed.

Nutrient Intake and Nutritional Status in Adult Patients with Inherited Metabolic Diseases Treated with Low-Protein Diets: A Review on Urea Cycle Disorders and Branched Chain Organic Acidemias

Low-protein diets (LPDs) are the main treatment for urea cycle disorders (UCDs) and organic acidemias (OAs). In most cases, LPDs start in childhood and must be continued into adulthood. The improved life expectancy of patients with UCDs and OAs raises the question of their consequences on nutritional status in adult subjects. As this topic has so far received little attention, we conducted a review of scientific studies that investigated the nutrient intake and nutritional status in adult patients with UCDs and branched chain organic acidemias (BCOAs) on LPD.

METHODS

The literature search was conducted in PubMed/MEDLINE, Scopus, EMBASE and Google Scholar from 1 January 2000 to 31 May 2020, focusing on nutrient intake and nutritional status in UCD and OA adult patients.

RESULTS

Despite protein restriction is recommended as the main treatment for UCDs and OAs, in these patients, protein intake ranges widely, with many patients who do not reach safety levels. When evaluated, micronutrient intake resulted below recommended values in some patients. Lean body mass resulted in most cases lower than normal range while fat body mass (FM) was often found normal or higher than the controls or reference values. Protein intake correlated inversely with FM both in adult and pediatric UCD patients.

CONCLUSIONS

The clinical management of adult patients with UCDs and BCOAs should include an accurate assessment of the nutritional status and body composition. However, as little data is still available on this topic, further studies are needed to better clarify the effects of LPDs on nutritional status in adult UCD and BCOA patients.

Subtyping of Primary Aldosteronism in the AVIS-2 Study: Assessment of Selectivity and Lateralization

CONTEXT

Adrenal venous sampling (AVS) is the key test for subtyping primary aldosteronism (PA), but its interpretation varies widely across referral centers and this can adversely affect the management of PA patients.

OBJECTIVES

To investigate in a real-life study the rate of bilateral success and identification of unilateral aldosteronism and their impact on blood pressure outcomes in PA subtyped by AVS.

DESIGN AND SETTINGS

In a retrospective analysis of the largest international registry of individual AVS data (AVIS-2 study), we investigated how different cut-off values of the selectivity index (SI) and lateralization index (LI) affected rate of bilateral success, identification of unilateral aldosteronism, and blood pressure outcomes.

RESULTS

AVIS-2 recruited 1625 individual AVS studies performed between 2000 and 2015 in 19 tertiary referral centers. Under unstimulated conditions, the rate of biochemically confirmed bilateral AVS success progressively decreased with increasing SI cut-offs; furthermore, with currently used LI cut-offs, the rate of identified unilateral PA leading to adrenalectomy was as low as <25%. A within-patient pairwise comparison of 402 AVS performed both under unstimulated and cosyntropin-stimulated conditions showed that cosyntropin increased the confirmed rate of bilateral selectivity for SI cut-offs ≥ 2.0, but reduced lateralization rates (P < 0.001). Post-adrenalectomy outcomes were not improved by use of cosyntropin or more restrictive diagnostic criteria.

CONCLUSION

Commonly used SI and LI cut-offs are associated with disappointingly low rates of biochemically defined AVS success and identified unilateral PA. Evidence-based protocols entailing less restrictive interpretative cut-offs might optimize the clinical use of this costly and invasive test. (J Clin Endocrinol Metab XX: 0-0, 2020).

Disease monitoring of Primary Aldosteronism

Primary aldosteronism (PA) is a highly prevalent cause of arterial hypertension featuring excess cardiovascular events. A timely diagnosis and treatment of PA cures hyperaldosteronism and can provide resolution or improvement of arterial hypertension, even when the latter is resistant to drug treatment. Accordingly, strategies to screen early and widely the hypertensive patients for PA by means of simplified diagnostic algorithms are justified. Such strategies are particularly beneficial in subgroups of hypertensive patients, who are at the highest cardiovascular risk. Broadening of screening strategies means facing with an increased number of patients where monitoring the disease becomes necessary. Hence, after identification of the surgically and non surgically curable cases of PA and implementation of targeted treatment physicians are faced with the challenges of follow-up, which are scantly discussed in the literature. Hence, the purpose of this paper is to provide some recommendations on how to optimize the monitoring of patients in whom the PA subtype has been diagnosed and treatment, either with unilateral laparoscopic adrenalectomy or medically, has been instituted.

Aldosterone Stimulates Its Biosynthesis Via a Novel GPER-Mediated Mechanism

CONTEXT

The G protein-coupled estrogen receptor (GPER) mediates an aldosterone secretagogue effect of 17β-estradiol in human HAC15 adrenocortical cells after estrogen receptor β blockade. Because GPER mediates mineralocorticoid receptor-independent aldosterone effects in other cell types, we hypothesized that aldosterone could modulate its own synthesis via GPER activation.

METHODS

HAC15 cells were exposed to aldosterone in the presence or absence of canrenone, a mineralocorticoid receptor antagonist, and/or of the selective GPER antagonist G36. Aldosterone synthase (CYP11B2) mRNA and protein levels changes were the study end points. Similar experiments were repeated in strips obtained ex vivo from aldosterone-producing adenoma (APA) and in GPER-silenced HAC15 cells.

RESULTS

Aldosterone markedly increased CYP11B2 mRNA and protein expression (vs untreated samples, P < 0.001) in both models by acting via GPER, because these effects were abolished by G36 (P < 0.01) and not by canrenone. GPER-silencing (P < 0.01) abolished the aldosterone-induced increase of CYP11B2, thus proving that aldosterone acts via GPER to augment the step-limiting mitochondrial enzyme (CYP11B2) of its synthesis. Angiotensin II potentiated the GPER-mediated effect of aldosterone on CYP11B2. Coimmunoprecipitation studies provided evidence for GPER-angiotensin type-1 receptor heterodimerization.

CONCLUSION

We propose that this autocrine-paracrine mechanism could enhance aldosterone biosynthesis under conditions of immediate physiological need in which the renin-angiotensin-aldosterone system is stimulated as, for example, hypovolemia. Moreover, as APA overexpresses GPER this mechanism could contribute to the aldosterone excess that occurs in primary aldosteronism in a seemingly autonomous fashion from angiotensin II.

Adrenal venous sampling: cosyntropin stimulation or not?

Notwithstanding the high prevalence of primary aldosteronism (PA), probably the most common form of secondary hypertension, the diagnosis of PA is often neglected or delayed, thus precluding target treatment, which is curative in many cases. For selection of the most appropriate treatment, a fundamental step is the distinction between a lateralized form, mainly aldosterone-producing adenoma (APA), and bilateral adrenocortical hyperplasia (BAH), also known as idiopathic hyperaldosteronism (IHA). To this aim all current guidelines recommend adrenal vein sampling (AVS), a technically challenging procedure that often fails, particularly in non-experienced hands. Cosyntropin (synthetic ACTH) is administered in the attempt to maximize adrenal cortisol secretion and avoid pulsatile adrenocortical hormone secretion in about 40% of the referral centres around the world. However, the Endocrine Society guidelines do not advise about the use or not of cosyntropin as stimulus during AVS, as there are arguments in favour and against its use. These arguments are presented in this debate article reflecting the views of groups that currently use and do not use cosyntropin.

PTH Modulation by Aldosterone and Angiotensin II is Blunted in Hyperaldosteronism and Rescued by Adrenalectomy

CONTEXT

Accumulating evidence suggests a link between adrenocortical zona glomerulosa and parathyroid gland through mechanisms that remain unexplored.

OBJECTIVES

To test the hypothesis that in vivo angiotensin II blockade affects PTH secretion in patients with hypertension and that aldosterone and angiotensim II directly stimulate PTH secretion ex vivo.

DESIGN AND SETTING

We investigated the changes of serum PTH levels induced by oral captopril (50 mg) administration in patients with primary essential hypertension (EH) and with primary aldosteronism (PA) caused by bilateral adrenal hyperplasia (BAH) or aldosterone-producing adenoma (APA), the latter before and after adrenalectomy. We also exposed primary cultures of human parathyroid cells from patients with primary hyperparathyroidism to angiotensin II (10-7 M) and/or aldosterone (10-7 M).

RESULTS

Captopril lowered PTH levels (in nanograms per liter) both in patients with EH (n = 63; 25.9 ± 8.3 baseline vs 24.4 ± 8.0 postcaptopril, P < 0.0001) and in patients with APA after adrenalectomy (n = 27; 26.3 ± 11.6 vs 24.0 ± 9.7 P = 0.021). However, it was ineffective in patients with full-blown PA caused by APA and BAH. In primary culture of human parathyroid cells, both aldosterone (P < 0.001) and angiotensin II (P = 0.002) markedly increased PTH secretion from baseline, by acting through mineralocorticoid receptor and angiotensin type 1 receptor, as these effects were abolished by canrenone and irbesartan, respectively.

CONCLUSION

These results collectively suggest an implication of the renin-angiotensin-aldosterone system in PTH regulation in humans, at least in PTH-secreting cells obtained from parathyroid tumors. Moreover, they further support the concept that mild hyperparathyroidism is a feature of human PA that is correctable with adrenalectomy.

Abstract 058: High Sodium Intake Induces a Catabolic State via Glomerular Hyperfiltration and Enhanced Glomerulotubular Balance in Essential Hypertension

Background: A metabolic shift in energy expenditure toward a catabolic state upon high sodium (Na + ) diet, ultimately favouring endogenous water accrual and body fluid preservation, has recently been described in a rodent model.

Objective: To investigate the impact of high Na + intake on renal Na + /water handling and metabolic signatures in a large real-life cohort of patients.

Methods and Results: We analysed biochemical data from 767 hypertensive patients (429 males, 55.9%; age 47 ± 13 years; BMI 25.6 [23.0-29.0] kg/m 2 ) in washout from drugs affecting the renin-angiotensin-aldosterone system at the time of screening for secondary causes and with a conclusive diagnosis of essential hypertension (2012-2017). Classes of Na + intake ( L ow ≤2.3g/d; M edium 2.3-5g/d; H igh >5g/d) were defined based on urinary 24h Na + excretion (uNaV). The fractional excretion (FE) of Na + increased with increasing Na + intake (L: 0.39% [0.30-0.47] vs H: 0.81% [0.73-0.98], p < 0.001), while FE of free water decreased (L: 1.13% [0.73-1.72] vs H: 0.89% [0.69-1.12], p = 0.015). uNaV was an independent predictor of glomerular filtration rate (GFR, estimated by creatinine clearance; H: 130 ± 33 vs M: 111 ± 52 and L: 96 ± 39 ml/min/1.73m 2 ; p < 0.001 for comparisons) after correction for age, sex, BMI, renin, aldosterone and uKV (p = 0.001). This resulted in a marked increase in the 24h tubular Na + reabsorption and, accordingly, in the estimated energy expenditure (Δ H vs L= 18 [12-24] kcal/d, p < 0.001). At non-targeted LC/MS metabolomics (n = 67), metabolites increased (p < 0.05) in H vs L Na + intake mostly entailed intermediates or end products of the urea cycle and products of protein catabolism. Urinary 24h cortisol excretion, as a potential determinant of catabolism, increased with Na + intake (n = 137; L: 63 [36-72] nmol, M: 60 [47-86] nmol, H: 86 [75-139] nmol; p < 0.001), but its strongest predictor at multivariate regression analysis was GFR (p = 0.001).

Conclusions: Kidneys can effectively dissociate Na + and water handling upon high Na + diet, at the cost of glomerular hyperfiltration, enhanced glomerulotubular balance, increased tubular energy expenditure and, ultimately, protein catabolism from endogenous or excess exogenous sources. This has broad implications on global cardiovascular risk.

Mutations of the Twik-Related Acid-Sensitive K+ Channel 2 Promoter in Human Primary Aldosteronism

Because blunted expression of the twik-related acid-sensitive K+ channel 2 (TASK-2) is a common feature of aldosterone-producing adenoma (APA) causing primary aldosteronism (PA), we sequenced the promoter region of the TASK-2 gene (KCNK5) in APAs (n = 76), primary hypertensive patients (n = 98), and 20-year-old healthy volunteers (n = 71), searching for variants that could affect expression of this channel. We found TASK-2 promoter mutations in 25% of the APAs: C999T in 6.6%, G595A in 5.3%, G36A in 5.3%, and C562T, Gins468, G265C, C1247T, G1140T, and C1399T in 1.3% each. The C999T mutation was found in only one of the 98 primary hypertensive patients, but mutations were detected also in 12% of volunteers: 4 carried the C999T, 3 G1288C, 1 the G1140T mutation, and 1 the 468ins mutation. After a 16-year follow-up, none of these patients developed hypertension or PA. The effect of C999T mutation was investigated in H295R cells using reporter vectors with the mutated or the wild-type (WT) TASK-2 promoters. TASK-2 gene expression was decreased by 31% ± 18% (P = 0.01) in mutated compared with WT APA. Likewise, in transfected H295R cells, the C999T mutation decreased TASK-2 transcriptional activity by 35% (normalized luciferase signal fold change: 0.65 ± 0.25, P < 0.001). Thus, mutations in the promoter region of the TASK-2 gene can account for the low expression in ∼25% of APAs. As they did not result in hypertension or PA during long-term follow-up in healthy participants, these mutations do not seem to be a factor in causing PA by themselves.

Genetic screening in arterial hypertension

Studies involving adoptive families and twins have demonstrated the genetic basis of hypertension and shown that genetic factors account for about 40% of the variance in blood pressure among individuals. Arterial hypertension is genetically complex: multiple genes influence the blood pressure phenotype through allelic effects from single genes and gene-gene interactions. Moreover, environmental factors also modify the blood pressure phenotype. This complexity explains why the identification of the underlying genes has not been as successful in hypertension as in other diseases (such as type 1 and type 2 diabetes mellitus). The identification of the genetic determinants of hypertension has been most successful in endocrine forms of hypertension, which have well-defined phenotypes that permit a precise patient stratification into homogeneous cohorts. A promising area for the application of genetic testing to personalized medicine is the prediction of responses and adverse reactions to antihypertensive drugs. The identification of genetic markers of drug response will enable the design of randomized controlled trials in much smaller series of patients than is currently possible, decreasing the costs and times from drug design to clinical use and ultimately providing patients and doctors with a larger number of tools to combat hypertension, the most important risk factor for cardiovascular disease. This Review focuses on the rapidly developing field of genetic testing in patients with arterial hypertension.

Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases

BACKGROUND

A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors.

OBJECTIVES

By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes.

METHODS

A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.

Abstract P212: A Meta Analysis of Somatic KCNJ5 Mutations in 1636 Primary Aldosteronism Patients

Background: We meta-analysed the available studies reporting on KCNJ5 mutations in Aldosterone Producing Adenoma (APA) to determine the clinical characteristics of APA patients with a mutation of the KCNJ5 gene.

Methods: We applied the PICO strategy using predefined terms (Population: primary aldosteronism patients with aldosterone producing adenoma; Intervention: adrenalectomy, sequencing for KCNJ5 mutations; Control: APA without KCNJ5 mutations; Outcome: clinical and pathological correlates of KCNJ5 mutations) to extract relevant studies from the PubMed, Scopus, Web of Science e Cochrane databases until January 2015. To allow for independent replication of the results, we elected to use the commercially available software.

Results and Conclusions: By this PICO strategy we could identify 13 studies involving a total of 1636 patients (age 49 years ± 4; 55% females). The overall prevalence of KCNJ5 mutations was 43%; it was lower frequency (p<0.003) in European, USA and Australian studies (35%) than in Japanese and Chinese studies (63%), and correlated (r=0.70, p=0.008) with the mean daily urinary sodium excretion. The meta-analysis comparison of wild-type and KCNJ5 mutated patients demonstrated that the latter were younger (45±3 vs 52±5 years), had higher plasma aldosterone levels (42±8 vs 33±8 ng/dl), bigger tumors (16.1±6.4 vs 14.9±7.4 mm) and were more females (67% vs 44%) (p<0.05 for all). At variance, no significant effect of KCNJ5 mutations on systolic and diastolic blood pressure, and on serum potassium could be found.

Therefore, the meta-analysis of a large dataset comprising all studies available thus far showed that features associated with the presence of KCNJ5 mutations in PA due to APA entail young age, female gender, bigger tumor size and more prominent hyperaldosteronism.

Lipoprotein-associated phospholipase A2 single-nucleotide polymorphisms and cardiovascular events in patients with coronary artery disease

AIMS

We tested the hypothesis that variations in the PLA2G7 gene encoding the lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme deemed to have proatherogenic activity, affect the Lp-PLA2 levels and predicts cardiovascular events.

METHODS

Using a prospective cohort study design, we investigated incident cardiovascular events as a function of the PLA2G7 gene for rs1805017, rs1805018, and rs1051931 single-nucleotide polymorphisms (SNPs) in 643 randomly selected white patients from the GENICA Study, who at baseline underwent coronary angiography, measurement of Lp-PLA2 mass and activity. Cardiovascular event-free survival was compared across the genotypes by Cox regression, propensity score matching, and haplotype analysis.

RESULTS

The rs1805018 SNP did not follow the Hardy-Weinberg equilibrium and was not further explored. The rs1805017 GG genotype had a lower Lp-PLA2 mass and a higher Lp-PLA2 activity, thus suggesting that this SNP is functional. Long-term follow-up (median 7.8 years) was obtained in 75% of the cohort and allowed recording of incident cardiovascular events in 25.8% of the patients. On Cox regression analysis, the common rs1805017 GG genotype predicted acute myocardial infarction (AMI) [hazard ratio 1.75, 95% confidence interval (CI) 1.03-2.99, P = 0.041]; this finding was confirmed on propensity score matching (82.6% AMI-free survival in GG vs. 94.4% in GA + AA, P = 0.003). The rs1805017 and rs1051931 G/G haplotype was also associated with AMI (52.7 vs. 42.2%, P = 0.026) and cardiovascular event incidence (49.5 vs. 41.7%, P = 0.025).

CONCLUSION

In high-risk coronary artery disease patients of European ancestry, the PLA2G7 rs1805017 GG genotype is associated with increased Lp-PLA2 plasma activity and AMI.

A Meta-Analysis of Somatic KCNJ5 K(+) Channel Mutations In 1636 Patients With an Aldosterone-Producing Adenoma

CONTEXT

Due to selection biases and inadequate statistical power, individual studies may fail to identify the clinical features of patients with an aldosterone-producing adenoma (APA) harboring KCNJ5 mutations. When this failure occurs, meta-analysis can provide significant outcome data.

OBJECTIVE

The objective was to determine the clinical features of these APA patients.

DESIGN

We systematically searched the PubMed, Scopus, Web of Science, and Cochrane databases library in January 2015 applying the Population, Intervention, Comparison, and Outcome (PICO) strategy. The standardized differences in mean and corresponding 95% confidence interval of continuous variables were computed by random-effects modeling.

SETTING

We performed a meta-analysis of all available studies on somatic KCNJ5 mutations in APA.

PATIENTS

We could identify 13 studies that recruited 1636 patients (age 49 ± 4 years; 55% females).

MAIN OUTCOMES AND MEASURES

Differences between APA with and without KCNJ5 mutations in gender, plasma renin activity, plasma aldosterone, tumor size, serum potassium, and blood pressure were investigated.

RESULTS

The overall prevalence of KCNJ5 mutations was 43% (range = 12-80%). Their rate was lower (P < .003) in the studies done in Europe, the United States, and Australia (35%) than in Japan and China (63%); it correlated (r = 0.60, P = .029) with the mean daily urinary sodium excretion. Compared with the wild-type, the mutated APA patients were younger (45 ± 3 vs 52 ± 5 yrs), had higher plasma aldosterone (42 ± 8 vs 33 ± 8 ng/dl), larger tumors (16.1 ± 6.4 versus 14.9 ± 7.4 mm), and were more often females (67% vs 44%) (all P < .05).

CONCLUSIONS

Meta-analysis showed that more pronounced hyperaldosteronism, young age, female gender, and larger tumors are the phenotypic features of APA patients with KCNJ5 mutations. No significant differences in blood pressure and serum K(+) was found, which suggests that these clinical features do not help in identifying mutated APA patients.

The molecular basis of primary aldosteronism: from chimeric gene to channelopathy

Primary aldosteronism (PA) is the most common endocrine cause of high blood pressure. Only a minority of the PA cases are familial and due to known (CYP11B2/CYP11B1 chimeric gene or mutations in the KCNJ5 gene) or unknown causes. In the most common sporadic cases the mechanisms by which the excess aldosterone production persists in spite of high blood pressure, sodium retention, suppression of the renin angiotensin system and low potassium levels, all factors that by themselves would be expected to shut off aldosterone production, were a puzzle for decades. Only recently the discovery of functional mutations and down-regulation of potassium channels provided some explanations. We herein reviewed these recent findings and their mechanistic implications. We also propose a clinical molecular classification of familial hyperaldosteronism, which can be important from the practical standpoint as it considers besides the molecular features also the responsiveness to treatment and the imaging features.

GPER-1 and estrogen receptor-β ligands modulate aldosterone synthesis

Fertile women have lower blood pressure and cardiovascular risk than age-matched men, which suggests that estrogens exert cardiovascular protective effects. However, whether 17 β-estradiol (E2) blunts aldosterone secretion, and thereby affects the gender dimorphism of blood pressure, is unknown. We therefore sought for the estrogen receptor (ER) subtypes in human adrenocortical tissues ex vivo by performing gene and protein expression studies. We also investigated the effect of E2 on aldosterone synthesis and the involved receptors through in vitro functional experiments in the adrenocortical cells HAC15. We found that in the human adrenal cortex and aldosterone-producing adenoma cells, the most expressed ERs were the ERβ and the G protein-coupled receptor-1 (GPER-1), respectively. After selective ERβ blockade, E2 (10 nmol/L) markedly increased both the expression of aldosterone synthase and the production of aldosterone (+5- to 7-fold vs baseline, P < .001). Under the same condition, the GPER-1 receptor agonist 1-[4-(6-bromo-benzo (1, 3)dioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c] quinolin-8-yl]-ethanone (G-1) (10 nmol/L) mimicked this effect, which was abrogated by cotreatment with either the GPER-1 receptor antagonist (3aS*,4R*,9bR*)-4-(6-Bro-mo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta[c]quinoline (G-15), or a selective protein kinase A inhibitor 8-Bromo-2-monobutyryladenosine-3,5-cyclic mono-phosphorothioate, Rp-isomer. Silencing of the ERβ significantly raised aldosterone synthase expression and aldosterone production. Conversely, silencing of the GPER-1 lowered aldosterone synthase gene and protein expression. Moreover, it blunted the stimulatory effect of E2 on aldosterone synthase that was seen during ERβ blockade. These results support the conclusion that in humans, E2 inhibits aldosterone synthesis by acting via ERβ. Pharmacologic disinhibition of ERβ unmasks a potent secretagogue effect of E2 that involves GPER-1 and protein kinase A signaling.

A novel KCNJ5-insT149 somatic mutation close to, but outside, the selectivity filter causes resistant hypertension by loss of selectivity for potassium

CONTEXT

Understanding the function of the KCNJ5 potassium channel through characterization of naturally occurring novel mutations is key for dissecting the mechanism(s) of autonomous aldosterone secretion in primary aldosteronism.

OBJECTIVE

We sought for such novel KCNJ5 channel mutations in a large database of patients with aldosterone-producing adenomas (APAs).

METHODS

We discovered a novel somatic c.446insAAC insertion, resulting in the mutant protein KCNJ5-insT149, in a patient with severe drug-resistant hypertension among 195 consecutive patients with a conclusive diagnosis of APA, 24.6% of whom showed somatic KCNJ5 mutations. By site-directed mutagenesis, we created the mutated cDNA that was transfected, along with KCNJ3 cDNA, in mammalian cells. We also localized CYP11B2 in the excised adrenal gland with immunohistochemistry and immunofluorescence using an antibody specific to human CYP11B2. Whole-cell patch clamp recordings, CYP11B2 mRNA, aldosterone measurement, and molecular modeling were performed to characterize the novel KCNJ5-insT149 mutation.

RESULTS

Compared with wild-type and mock-transfected adrenocortical cells, HAC15 cells expressing the mutant KCNJ5 showed increased CYP11B2 expression and aldosterone secretion. Mammalian cells expressing the mutated KCNJ5-insT149 channel exhibited a strong Na(+) inward current and, in parallel, a substantial rise in intracellular Ca(2+), caused by activation of voltage-gated Ca(2+) channels and reduced Ca(2+) elimination by Na(+)/Ca(2+) exchangers, as well as an increased production of aldosterone.

CONCLUSIONS

This novel mutation shows pathological Na(+) permeability, membrane depolarization, raised cytosolic Ca(2+), and increased aldosterone synthesis. Hence, a novel KCNJ5 channelopathy located after the pore α-helix preceding the selectivity filter causes constitutive secretion of aldosterone with ensuing resistant hypertension in a patient with a small APA.

Abstract 011: Identification and Electrophysiological Characterization of a Novel Somatic Mutation (insT149KCNJ5) of the Potassium Channel Kir3.4 (KCNJ5)

Context: Understanding the function of the Kir3.4 (KCNJ5 gene) potassium channel through characterization of occurring novel mutations is key for dissecting the mechanism(s) of autonomous aldosterone secretion in primary aldosteronism.

Objective: To identify novel KCNJ5 channel mutations and functionally characterize them in a large database of patients with aldosterone-producing adenomas (APA).

Methods: We sequenced the APA and germinal DNA of 195 consecutive patients, diagnosed with the four corners criteria of the PAPY study. Among the 24.6% (48/195) APA patients who showed somatic KCNJ5 mutations we discovered a novel c.446insAAC insertion resulting in the mutant protein KCNJ5-insT149 in a patient with severe drug-resistant hypertension. The mutated cDNA generated by site-directed mutagenesis was transfected along with KCNJ3 cDNA in mammalian cells. 17α-hydroxylase, CYP11B1, and CYP11B2 were immunochemically localized in the excised adrenal gland. Whole-cell patch clamp recordings, CYP11B2 mRNA, aldosterone and intracellular Ca2+ measurement (Fura-2), and molecular modeling were performed to characterize the KCNJ5-insT149 mutation.

Results: The patient’s high blood pressure was long-term cured; his LVMI fell from 168 to 106 g/m2 after 2 years follow-up. Compared to wild type and mock-transfected HAC15 adrenocortical cells, those expressing the mutant KCNJ5 showed increased CYP11B2 expression (expression fold change: 2.9±0.3, p<0.05 vs mock transfected cells) and aldosterone secretion (260 pg/μg RNA, p<0.05 vs mock cells). The HEK293 cells expressing the mutated KCNJ5-insT149 channel exhibited a strong Na+ inward current, and a substantial rise in intracellular Ca2+. The L-type Ca2+ channel blocker verapamil [10 μM] inhibited by 50% the pathological Na+ inward current, while both the Na+/Ca2+ exchanger blocker KB-R7943 [10 μM] and the removal of extracellular Na+ abolished it.

Conclusions: We identified a novel mutation of the Kir3.4 channelopathy located after the pore α-helix preceding the selectivity filter, which causes pathological Na+ permeability, membrane depolarization, raised cytosolic Ca2+, and constitutive hypersecretion of aldosterone resulting in ensuing pseudo resistant hypertension.

Lower expression of the TWIK-related acid-sensitive K+ channel 2 (TASK-2) gene is a hallmark of aldosterone-producing adenoma causing human primary aldosteronism

CONTEXT

The molecular mechanisms of primary aldosteronism, a common cause of human hypertension, are unknown, but alterations of K(+) channels can play a key role.

OBJECTIVE

The objective of the study was to investigate the following: 1) the expression of the Twik-related acid-sensitive K(+) channels (TASK) in aldosterone producing adenomas (APAs); 2) the role of TASK-2 in aldosterone synthesis; and 3) the determinants of TASK-2-blunted expression in APAs.

DESIGN

We analyzed the transcriptome and the microRNA profiles of 32 consecutive APAs and investigated the protein expression and localization of TASK-2 in APA and adrenocortical cell lines (H295R and HAC15) using immunoblotting and confocal microscopy. The functional effect of TASK-2 blunted activity caused by a dominant-negative mutation on steroidogenic enzymes, and aldosterone production was also assessed. TASK-2 regulation by selected microRNA was studied by a luciferase assay.

RESULTS

TASK-2 was consistently less expressed at the transcript and protein levels in APAs than in the normal human adrenal cortex. H295R cell transfection with a TASK-2 dominant-negative mutant construct significantly increased the aldosterone production by 153% and the gene expression of aldosterone synthase (CYP11B2, gene expression fold change 3.1 vs control, P < .05) and the steroidogenic acute regulatory protein (gene expression fold change 1.8 vs control, P < .05). Two microRNAs, hsa-miR-23 and hsa-miR-34, were found to decrease the TASK-2 expression by binding to the 3' untranslated region of the TASK-2 gene.

CONCLUSIONS

The TASK-2 channel lower expression represents a hallmark of APA and is associated with a higher expression of hsa-miR-23 and hsa-miR-34. The ensuing blunted TASK-2 activity increased the production of aldosterone in vitro and the expression of steroidogenic acute regulatory protein and CYP11B2. Hence, the lower expression of TASK-2 channel in APA cells can explain high aldosterone secretion in human primary aldosteronism despite the suppression of angiotensin II, hypertension, and hypokalemia.

Abstract 359: Modulation of Aldosterone Synthase by Estrogens: Evidence for an Interaction of Gper-1 and Estrogen B Receptors and Relevance for the Gender Dimorphism of Blood Pressure

Background. Fertile women have lower blood pressure and are held to be at lower risk for cardiovascular events than age-matched man. However, whether this gender dimorphism involves a modulation of aldosterone synthesis by 17 beta-estradiol (E2) is unknown.

Aims. i) To investigate estrogen receptor subtypes gene expression in the normal human adrenal cortex (NAC), in aldosterone producing adenoma (APA) and in a human adrenocortical carcinoma cell line (HAC15); ii) To assess the effect of E2 on aldosterone synthase (CYP11B2) gene expression and to identify the receptor subtypes involved in this effect.

Methods. We measured the expression of alpha (ERa), beta (ERb) and of G protein-coupled receptor (GPER-1)-1 in NAC and in APA tissue, and in HAC15 cells by real time RT-PCR. After demonstration that HAC15 cells express ERa, ERb, and GPER-1 we stimulated cells with 10-7M E2 alone, or after ERb selective blockade with 10-5M tetrahydrochrysenediol (THC), ERa selective blockade with 10-5M MPP dihydrochloride (MPP), non selective ERa and ERb blockade with 10-5M ICI 182.780, or after selective GPER-1 receptor blockade with 10-5M G-15. The cells were also exposed to the GPER-1 agonist G-1, alone or in the presence of MPP, THC, or Fulvestrant, and/or G-15. Changes of expression of CYP11B2 mRNA, measured with RT RT-PCR, was the experimental endpoint.

Results. The quantitative expression of estrogen receptor subtypes was ERb > GPER-1 >> ERα in NAC, GPER-1 > ERb> ERa in APA, and ERb>ERa=GPER-1 in HAC15 cells. E2 alone or on top of selective ERa antagonism did not alter CYP11B2 expression. By contrast, E2 significantly increased CYP11B2 expression (+500 to + 700% from baseline, p <0.001) after selective ERb antagonism, or combined ERa and ERb blockade. Likewise, G-1 markedly increased CYP11B2 gene after combined ERb blockade, an effect that was abolished by G15 co-treatment.

Conclusion. E2 potently stimulates aldosterone synthase expression via GPER-1 subtype receptor activation when the ERb is blocked. The ERb-mediated tonic inhibition of aldosterone synthase could contribute to explaining both the lower BP and CV risk of fertile women and the increase of BP after when this tonic ERb-mediated inhibition wanes during menopause or estrogen-modulation treatment.

Abstract 280: Modulation of Aldosterone Synthesis in Human Adrenocortical Cells by Estrogens via an Interaction on Beta Estrogen and Gpr30 Receptor Subtypes

Background and aim. The gender dimorphism in the pressor effect of hyperaldosteronism suggests that estrogens may modulate aldosterone synthesis. Estrogens were suggested to affect adrenocortical cell proliferation via beta estrogen receptor (ERβ), but it remains unknown if they also influence aldosterone synthesis.

Methods. We therefore investigated the expression of alpha (ERα), ERβ and of G protein-coupled receptor (GPR)30 in HAC15 cells, a human adrenocortical carcinoma cell line. HAC15 cells were stimulated with 10 -7 M 17β-estradiol (E2) alone, or with a selective ERβ antagonist (10 -5 M; Tetrahydrochrysenediol THC), a selective ERα antagonist (10 -5 M; MPP dihydrochloride), a non selective ERα and ERβ antagonist (10 -5 M; ICI 182.780 fulvestrant), a selective GPR30 receptor antagonist (10 -5 M; G-15). The cells were also exposed to the highly selective GPR30 agonist G-1, alone or in the presence of MPP, or THC, or Fulvestrant and G-15. CYP11B2 mRNA expression was measured with quantitative real time RT-PCR (Universal Probe Library Roche).

Results. The three estrogen receptor subtypes were found to be expressed at different levels (ERβ>>ERα=GPR30) in HAC15 cells. E2 alone or on top of selective ERα antagonism did not alter CYP11B2 expression. At variance, E2 on top of selective ERβ antagonism, or of combined ERβ and ERα antagonism, caused a 5- to 7- fold upregulation of CYP11B2 mRNA, a finding that was replicated by the exposure of cells to G-1 on top of combined ERβ and ERα blockade.

Conclusions . 1) GPR30 is expressed in human adrenocortical cells at levels that are comparable to ERα, but less abundatly than ERβ subtype receptor. 2) 17β-estradiol activates CYP11B2 synthesis via an interaction between ERβ blockade and GPR30 activation. Hence, by showing a role for estrogens in the regulation of aldosterone synthesis via GPR30 subtype receptor, these results could account for the diverse pressor effects of excess aldosterone in men and in fertile vs post-menopausal women.

Prevalence, Clinical, and Molecular Correlates of KCNJ5 Mutations in Primary Aldosteronism

Primary aldosteronism is the most common form of secondary hypertension. Mutations in the KCNJ5 gene have been described recently in aldosterone-producing adenomas (APAs). The aim of this study was to investigate the prevalence of KCNJ5 mutations in unselected patients with primary aldosteronism and their clinical, biological and molecular correlates. KCNJ5 sequencing was performed on somatic (APA, n=380) and peripheral (APA, n=344; bilateral adrenal hyperplasia, n=174) DNA of patients with primary aldosteronism, collected through the European Network for the Study of Adrenal Tumors. Transcriptome analysis was performed in 102 tumors. Somatic KCNJ5 mutations (p.Gly151Arg or p.Leu168Arg) were found in 34% (129 of 380) of APA. They were significantly more prevalent in females (49%) than males (19%; P <10 −3 ) and in younger patients (42.1±1.0 versus 47.6±0.7 years; P <10 −3 ) and were associated with higher preoperative aldosterone levels (455±26 versus 376±17 ng/L; P =0.012) but not with therapeutic outcome after surgery. Germline KCNJ5 mutations were found neither in patients with APA nor those with bilateral adrenal hyperplasia. Somatic KCNJ5 mutations were specific for APA, because they were not identified in 25 peritumoral adrenal tissues or 16 cortisol-producing adenomas. Hierarchical clustering of transcriptome profiles showed that APAs with p.Gly151Arg or p.Leu168Arg mutations were indistinguishable from tumors without KCNJ5 mutations. In conclusion, although a large proportion of sporadic APAs harbors somatic KCNJ5 mutations, germline mutations are not similarly causative for bilateral adrenal hyperplasia. KCNJ5 mutation carriers are more likely to be females; younger age and higher aldosterone levels at diagnosis suggest that KCNJ5 mutations may be associated with a more florid phenotype of primary aldosteronism.

Caldesmon over-expression in type 1 diabetic nephropathy

Substantial evidence supports a genetic susceptibility to develop nephropathy in type 1 diabetes and a key pathogenic role of actin cytoskeleton dysfunction in this complication. We previously reported that many cytoskeletal proteins were either up- or down-regulated in fibroblast cells from type 1 diabetic (T1DM) patients with nephropathy. The gene of one of these proteins, caldesmon, lies in a chromosomal region linked to nephropathy and its promoter region contains a single nucleotide polymorphism that is associated with nephropathy. Hence, we analyzed caldesmon gene and protein expression in cultured fibroblasts from T1DM patients with and without nephropathy and from control subjects. Caldesmon gene was studied in cells cultured under normal glucose levels by quantitative real-time RT-PCR. Caldesmon protein isoforms were quantified both under normal and high glucose conditions by two-dimensional electrophoresis. Caldesmon gene was over-expressed in fibroblasts from diabetic patients with nephropathy, in comparison to both those from diabetic patients without nephropathy and those from controls. We quantified six caldesmon protein isoforms, two of them were increased whereas another one was decreased only in fibroblasts from diabetic patients with nephropathy. None of these isoforms showed any difference in their relative abundance in response to high glucose. Variable results in response to high glucose were observed in the expression of other proteins in the three experimental groups. Our data lend further support to an involvement of caldesmon in the susceptibility to diabetic nephropathy in type 1 diabetes, independently from environmental glucose levels.

Expression and functional role of urotensin-II and its receptor in the adrenal cortex and medulla: novel insights for the pathophysiology of primary aldosteronism

CONTEXT

The involvement of urotensin II, a vasoactive peptide acting via the G protein-coupled urotensin II receptor, in arterial hypertension remains contentious.

OBJECTIVE

We investigated the expression of urotensin II and urotensin II receptor in adrenocortical and adrenomedullary tumors and the functional effects of urotensin II receptor activation.

DESIGN

The expression of urotensin II and urotensin II receptor was measured by real time RT-PCR in aldosterone-producing adenoma (n = 22) and pheochromocytoma (n = 10), using histologically normal adrenocortical (n = 6) and normal adrenomedullary (n = 5) tissue as control. Urotensin II peptide and urotensin II receptor protein were investigated with immunohistochemistry and immunoblotting. To identify urotensin II-related and urotensin II receptor-related pathways, a whole transcriptome analysis was used. The adrenocortical effects of urotensin II receptor activation were also assessed by urotensin II infusion with/without the urotensin II receptor antagonist palosuran in rats.

RESULTS

Urotensin II was more expressed in pheochromocytoma than in aldosterone-producing adenoma tissue; the opposite was seen for the urotensin II receptor expression. Urotensin II receptor activation in vivo in rats enhanced (by 182 +/- 9%; P < 0.007) the adrenocortical expression of immunoreactive aldosterone synthase.

CONCLUSIONS

Urotensin II is a putative mediator of the effects of the adrenal medulla and pheochromocytoma on the adrenocortical zona glomerulosa. This pathophysiological link might account for the reported causal relationship between pheochromocytoma and primary aldosteronism.

A twin study of heritability of plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) mass and activity

OBJECTIVE

We investigated heritability of plasma levels (mass) and activity of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)).

MATERIALS AND METHODS

In 54 healthy twins pairs we estimated genetic variance and heritability of Lp-PLA(2) mass and activity using maximum likelihood and least squares methods. We estimated intra-class correlation (ICC) and proportion of additive genetic variance from a model comprising additive genetic influence (A), environmental effect common to cotwins (C) and individually unique environmental (E) influence (ACE) model.

RESULTS

Twenty-six twin pairs were monozygotic (MZ) and 28 dizygotic (DZ). The Lp-PLA(2) mass and activity showed a significant correlation (r=0.87, p<0.001) and the mean values were similar in MZ and DZ. ICC estimates of heritability for Lp-PLA(2) were 0.27 (mass) and 0.28 (activity); ACE model-based estimates of heritability were 0.37 (mass) and 0.54 (activity). Heritability estimates were not significant for Lp-PLA(2) mass, but significant for Lp-PLA(2) activity.

CONCLUSIONS

These results suggest heritability for activity, but not for mass, in healthy Caucasians.