Healthcare Challenges in the Management of Primary Aldosteronism in Southeast Asia

OBJECTIVE

While guidelines have been formulated for the management of primary aldosteronism (PA), following these recommendations may be challenging in developing countries with limited healthcare access. Hence, we aimed to assess the availability and affordability of healthcare resources for managing PA in the Association of Southeast Asian Nations (ASEAN) region, which includes low-middle-income countries.

DESIGN

We instituted a questionnaire-based survey to specialists managing PA, assessing the availability and affordability of investigations and treatment. Population and income status data were taken from the national census and registries.

RESULTS

Nine ASEAN country members (48 respondents) participated. While screening with aldosterone-renin-ratio is performed in all countries, confirmatory testing is routinely performed in only six countries due to lack of facilities and local assays, and cost constraint. Assays are only locally available in four countries, and some centers have a test turnaround time exceeding three weeks. In seven countries (combined population of 442 million), adrenal vein sampling (AVS) is not routinely performed due to insufficient radiological facilities or trained personnel, and cost constraint. Most patients have access to adrenalectomy and medications. In six countries, the cost of AVS and adrenalectomy combined is >30% of its annual gross domestic product per capita. While most patients had access to spironolactone, it was not universally affordable.

CONCLUSION

Large populations currently do not have access to the healthcare resources required for the optimal management of PA. Greater efforts are required to improve healthcare access and affordability. Future guideline revisions for PA may need to consider these limitations.

Identifying KCNJ5 Mutation in Aldosterone-Producing Adenoma Patients With Baseline Characteristics Using Machine Learning Technology

Background

Primary aldosteronism is characterized by inappropriate aldosterone production, and unilateral aldosterone-producing adenoma (uPA) is a common type of PA. KCNJ5 mutation is a protective factor in uPA; however, there is no preoperative approach to detect KCNJ5 mutation in patients with uPA.

Objectives

This study aimed to provide a personalized surgical recommendation that enables more confidence in advising patients to pursue surgical treatment.

Methods

We enrolled 328 patients with uPA harboring KCNJ5 mutations (n = 158) or not (n = 170) who had undergone adrenalectomy. Eighty-seven features were collected, including demographics, various blood and urine test results, and clinical comorbidities. We designed 2 versions of the prediction model: one for institutes with complete blood tests (full version), and the other for institutes that may not be equipped with comprehensive testing facilities (condensed version).

Results

The results show that in the full version, the Light Gradient Boosting Machine outperformed other classifiers, achieving area under the curve and accuracy values of 0.905 and 0.864, respectively. The Light Gradient Boosting Machine also showed excellent performance in the condensed version, achieving area under the curve and accuracy values of 0.867 and 0.803, respectively.

Conclusions

We simplified the preoperative diagnosis of KCNJ5 mutations successfully using machine learning. The proposed lightweight tool that requires only baseline characteristics and blood/urine test results can be widely applied and can aid personalized prediction during preoperative counseling for patients with uPA.

ODP586 Analysis of Adrenal Vein Sampling (AVS) Success: A Retrospective Study of Primary Aldosteronism Patients at the National University of Malaysia (UKM) Medical Center

 

Currently, the gold standard for identifying a unilateral Primary Aldosteronism (PA) is adrenal vein sampling (AVS), an invasive and technically challenging procedure. In this study, we aim to identify the clinical-laboratory characteristics associated with successful AVS, and clinical parameters associated with PA patients that had successful AVS (on 1st, 2nd, or 3rd attempt), or had rejected further attempts after a failed AVS attempt.100 records of AVS from eighty-three AVS patients conducted between 2015 and 2020 at the National University of Malaysia (UKM) Medical Centre, Kuala Lumpur, Malaysia were analysed retrospectively. Of the 83 PA patients studied, 47 were performed on men and 36 were on women. Variables significantly associated with patients who booked for a further attempt of AVS was having a serum aldosterone of <300pg/ml compared to those who rejected further attempts. There was also a trend for those who rejected further attempts to have a shorter duration of hypertension. Over one third of patient's have a failed AVS on 1st attempt and more than half do not wish to reattempt this invasive procedure. A biomarker for those that achieve complete cure should be identified to give incentives to the PA patients to proceed with AVS.

Presentation: No date and time listed

PSUN14 Elucidating Effect of Modulating Aldosterone Synthesis on Cell Fate in Human Adrenal Cells

Introduction

Aldosterone regulates sodium homeostasis thereby affecting blood volume and blood pressure. Physiologically, aldosterone is synthesized in the zona glomerulosa (ZG) by aldosterone synthase (CYP11B2) when there is a lack of salt. However, in the adult human adrenal ZG is sparse and confined to discrete islets (1). We hypothesize that the high salt in modern diets change ZG cell function from synthesis to apoptosis/migration mode when aldosterone is not required. This hypothesis is based on: [i] CYP11B2−/− mice, where ZG cells migrate and apoptose (2); [ii] the disappearance from most of human ZG of CYP11B2, which became apparent with selective antisera (3); [iii] apoptosis in monkeys following aldosterone synthase inhibition (4). Herein we aim to test our hypothesis by silencing CYP11B2 in human adrenal cells.

Methods

The HAC15, a subclone of the H295R human adrenocortical cancer cell line, was transfected with scrambled siRNA (siScrambled) or siRNA targeting CYP11B2 (siCYP11B2) using the Neon™ Transfection System (Thermofisher Scientific, USA). An apoptosis assay 48-h post-transfection was performed using the Pacific Blue™ Annexin V/SYTOX™ AADvanced™ apoptosis kit on the BD FACSVerseTM system (BD Biosciences, USA). The supernatants and cells were harvested for aldosterone and cortisol, and RNA isolation. Experiments were repeated 3 times independently in triplicates. RNA-Sequencing (RNAseq) of siCYP11B2 and siScrambled was performed on a representative sample from each independent experiment (BGI Genomics, China).

Results

Transfected HAC15 cells with siCYP11B2 showed reduction of aldosterone production by 69.8% (p=0.001) and suppression of CYP11B2 mRNA by 8 folds (p=0.001) compared to control, with no significant change on cortisol production and CYP11B1 mRNA expression. This confirmed that the silencing was specific to CYP11B2 despite the gene being highly homologous to CYP11B1. In all 3 independent experiments, 3 genes were significantly downregulated; CYP11B2, HNRNPA1, and UHMK1 expression in siCYP11B2 cells were 32%, 65% and 67% of matched control siScramble cells. Result of KEGG pathway from each independent experiment showed the most enriched pathways among the differentially expressed genes (DEG) were mitophagy and autophagy. However, analysis of flow cytometric apoptosis assay showed silencing of CYP11B2 did not induce cell apoptosis.

Conclusion

Our finding showed that silencing of CYP11B2 can affect mitophagy and autophagy but does not affect cell apoptosis in the HAC15 human adrenocortical cancer cell line. Further investigation on cell proliferation and in non-cancerous adrenal cells may be needed to identify the effect of modulating aldosterone synthesis on ZG cell fate.

Reference

(1) Vinson G., Front Neurosci 2016; 10: 238. (2) Lee G, et al., Endocrinology 2005; 146: 2650–2656. (3) Gomez-Sanchez CE, et al., Mol Cell Endocrinol 2014; 383: 111–117. (4) Bogman K, et al., Hypertension. 2017; 69(1): 189–196.

Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Associated genetic polymorphisms and clinical manifestations in systemic lupus erythematosus in Asian populations - A systematic literature review

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic and life-threatening autoimmune disease. Its prevalence and clinical manifestations are known to be particularly severe in the Asian populations. Although genetics is known to play an important role in SLE susceptibility and clinical manifestations, the specific polymorphisms associated with these phenotypes in Asia are unclear. Therefore, we aim to review the association of SLE genetic polymorphisms with lupus manifestations across Asian populations and their role in the pathogenesis of SLE.

METHODS

A systematic search was conducted on PubMed, EBSCOHost, and Web of Science. We identified 22 casecontrol studies that matched our inclusion and exclusion criteria. Information such as study characteristics, genetic polymorphisms associated with SLE, and organ manifestations was extracted and reported in this review.

RESULTS

In total, 30 polymorphisms in 16 genes were found to be associated with SLE among Asians. All included polymorphisms also reported associations with various SLE clinical features. The association of rs1234315 in TNFSF4 linking to SLE susceptibility (P=4.17x10-17 OR=1.45 95% CI=1.34-1.59) and musculoskeletal manifestation (P=3.35x10-9, OR=1.37, 95%CI= 1.23-1.51) might be the most potential biomarkers to differentiate SLE between Asian and other populations. In fact, these associated genetic variants were found in loci that were implicated in immune systems, signal transduction, gene expression that play important roles in SLE pathogenesis.

DISCUSSIONS AND CONCLUSIONS

This review summarized the potential correlation between 30 genetic polymorphisms associated with SLE and its clinical manifestations among Asians. More efforts in dissecting the functional implications and linkage disequilibrium of associated variants may be required to validate these findings.

Functional Characteristic and Significance of Aldosterone-Producing Cell Clusters in Primary Aldosteronism and Age-Related Hypertension

Primary aldosteronism (PA) is one of the most frequent curable forms of secondary hypertension. It can be caused by the overproduction of aldosterone in one or both adrenal glands. The most common subtypes of PA are unilateral aldosterone over-production due to aldosterone-producing adenomas (APA) or bilateral aldosterone over-production due to bilateral hyperaldosteronism (BHA). Utilizing the immunohistochemical (IHC) detection of aldosterone synthase (CYP11B2) has allowed the identification of aldosterone-producing cell clusters (APCCs) with unique focal localization positive for CYP11B2 expression in the subcapsular portion of the human adult adrenal cortex. The presence of CYP11B2 supports that synthesis of aldosterone can occur in these cell clusters and therefore might contribute to hyperaldosteronism. However, the significance of the steroidogenic properties of APCCs especially in regards to PA remains unclear. Herein, we review the available evidence on the presence of APCCs in normal adrenals and adrenal tissues adjacent to APAs, their aldosterone-stimulating somatic gene mutations, and their accumulation during the ageing process; raising the possibility that APCCs may play a role in the development of PA and age-related hypertension.

Estrogen Receptors in Nonfunctioning Pituitary Neuroendocrine Tumors: Review on Expression and Gonadotroph Functions

AbstractEstrogen (17β-estradiol or E2) is a crucial regulator of the synthesis and secretion of pituitary reproductive hormones luteinizing hormone, follicle-stimulating hormone, and prolactin. In this review, we summarize the role of estrogen receptors in nonfunctioning pituitary neuroendocrine tumors (NF-Pitnets), focusing on immunoexpression and gonadotroph cell proliferation and apoptosis. Gonadotroph tumors are the most common subtype of NF-Pitnets. Two major estrogen receptor (ER) isoforms expressed in the pituitary are estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). Overall, estrogen actions are mostly exerted through the ERα isoform on the pituitary. The G protein–coupled estrogen receptor (GPER) located at the plasma membrane may contribute to nongenomic effects of estrogen. Nuclear immunoreactivity for ERα and ERβ was highest among gonadotroph and null cell tumors. Silent corticotroph tumors are the least immunoreactive for both receptors. A significantly elevated ERα expression was observed in macroadenomas compared with microadenomas. ERα and ERβ may act in opposite directions to regulate the Slug-E-cadherin pathway and to affect invasiveness of NF-Pitnets. In the cellular pathway, ERs regulate estrogen-induced proliferation and differentiation and impact several signaling pathways including the MAPK and PI3K/Akt pathway. Estrogen was the first-discovered inducer of pituitary tumor transforming gene 1 that was abundantly expressed in NF-Pitnets. ERα can be a potential biomarker for predicting tumor size and invasiveness as well as therapeutic target for NF-Pitnets. Selective estrogen receptor modulators or antiestrogen may represent as an alternative choice for the treatment of NF-Pitnets.

SUN-220 High Salt Intake May Paradoxically Drive Autonomous Aldosterone Production

Many modifiable factors contribute to the high prevalence rates of hypertension, among them is the consumption of too much salt (sodium). Another curable cause of hypertension is the excess of the hormone aldosterone. Aldosterone is normally produced by the zona glomerulosa (ZG) of the adrenal glands in response to a lack of salt and conversely suppressed by salt excess. We hypothesize that [i] suppression of aldosterone production induces apoptosis of ZG cells, as occurs following genetic deletion1; [ii] this sets up a maladaptive response to chronic salt overload by conferring a survival advantage to cells in which mutations drive autonomous aldosterone production. To address [i], we measured apoptosis of cells in which aldosterone synthesis was inhibited; to address [ii] we undertook a cross-sectional clinical study of aldosterone and sodium excretion, hypothesising that aldosterone excretion will be highest in the outside quartiles of sodium excretion. Aldosterone was inhibited by modification, in human adrenocortical H295R cells, of either CADM1 expression (mutated in aldosterone-producing adenomas2) or intracellular calcium concentration3. Apoptosis was measured by flow cytometric analysis of annexin V conjugates. 24-hour urinary aldosterone excretion (24h-Ualdo) was correlated with 24-hour urinary sodium (24h-Usodium) in 24h-urine samples collected for a Malaysian population-based salt intake study (MyCoSS). The prevalence of autonomous aldosterone production was estimated from the proportion of subjects with serum measurement whose “SUSSPUP” ratio (= serum sodium to urinary sodium)/(serum potassium2 to urinary potassium) was >5.34. Modification of CADM1 in human adrenocortical H295R cells decreased aldosterone production by half compared to vector control, and this was associated with a 3 to 5-fold increase of apoptotic cells (p<0.05; n>3). Pilot investigation of a Cav1.3 inhibitor decreased aldosterone production by 70%, and increased apoptosis by 7-fold (p<0.10; n=2). In 767 subjects, 24h-urine samples from the high urinary sodium quartile (>150mmol/d) had higher urinary aldosterone (4+0.18 ug/d) than other quartiles (p=0.00001). Overall, the estimated prevalence of autonomous aldossterone production using SUSSPUP ratio was 4.5% (8 of 179 subjects). In 63 subjects with 24h-Usodium>200 mmol/day, autonomous aldosterone secretion (conventionally >10µg/d) was found in 9.5%. Our results support the hypothesis that initial suppression of aldosterone production by salt excess may create a selective advantage for cells which autonomously produce aldosterone, and hence an inappropriate long-term increase in aldosterone production.

1Lee et al., Endocrinology. 2005;146:2650-6.

2Wu et al., 21st European Congress of Endocrinology. Vol. 63. BioScientifica, 2019.

3Xie et al., Sci Rep. 2016;6:24697.

4Willenberg et al., Eur J Clin Invest. 2009;39:43-50.

SUN-711 Association of Single Nucleotide Polymorphisms of CYP11B2, CYP11B1 and CYP17A1 with Primary Aldosteronism in a Multi-Ethnic Malaysian Cohort

Primary aldosteronism (PA), also known as Conn’s syndrome, is a common curable cause of hypertension. Family studies of essential hypertensive patients suggest that heritable genetic factors play a role in blood pressure regulation1. Interestingly, single nucleotide polymorphisms (SNP) in genes encoding enzymes involved with adrenal steroidogenesis, CYP11B2, CYP11B1 and CYP17A1, associate with increased risk of hypertension2. Therefore, we analysed whether selected SNPs in these genes are associated with PA. We performed an association study using genotype imputation for selected SNPs of the steroidogenic enzyme genes CYP11B2 (rs4546, rs1799998, rs13268025), CYP11B1 (rs6410, rs149845727), and CYP17A1 (rs1004467, rs138009835, rs2150927) from a pilot genome wide association study of Malaysian PA patients and healthy controls which was merged with the Singapore Genome Variation Project (SGVP) population dataset3. Genotype imputation for minor and major alleles was validated using PCR sequencing (n>10 for each genotype). Further, one SNP from each steroidogenic enzyme (CYP11B2:rs1799998, CYP11B1:rs6410 and CYP17A1:rs1004467) was validated using commercial TaqMan genotyping assays on the ABI 7000 Sequence Detection System which was performed on 149 PA patients and 78 non-hypertensive healthy individuals. Case-control genetic association analysis was performed at http://www.oege.org/software/orcalc.html and the association between genotypes and phenotypes was done using the independent-samples Kruskal-Wallis test on SPSS (version 25). The Minor Allele Frequencies (MAFs) for rs1004467, rs6410 and rs1799998 were similar to East Asian populations but differed significantly different from European, African, American and South Asian populations (rs1004467 MAF: C=0.258/298, rs6410 MAF: A=0.265/298, rs1799998 MAF: C=0.225/298). In Chinese patients matched by gender, heterozygotes for rs6410 had significantly increased risk of PA compared to common homozygotes (OR: 3.15, 95% CI: 1.01–9.8, p=0.04). Across patients of different ethnicity, the distribution of aldosterone levels was significantly different (p=0.039). In summary, only SNP rs6410 in Chinese patients matched by gender showed association with PA in our South East Asian cohort. More functional experiments need to be done to find out whether this is causal for PA or whether the SNP is in linkage disequilibrium with the actual functional causative SNPs. Once the functional SNP is known, identification of these germline variants in asymptomatic family members would allow early screening of PA to be offered and potentially provide novel drug targets to treat the disease.

References: 1Timberlake et al., Curr Opin Nephrol Hypertens. 2001 Jan;10(1):71-9. 2MacKenzie et al., Int J Mol Sci. 2017 Mar 7;18(3). pii: E579. 3Teo et al., Genome Res. 2009 Nov;19(11):2154-62.

Prevalence and Histopathological Characteristics of KCNJ5 Mutant Aldosterone-Producing Adenomas in a Multi-Ethnic Malaysian Cohort

Studies on excised adrenals from primary aldosteronism patients have found that somatic mutations in KCNJ5 frequently cause excess aldosterone production in the culprit aldosterone-producing adenoma (APA). KCNJ5 mutant APAs were reported to be peculiarly overrepresented among young females and in Oriental cohorts, compared to their older male, or Caucasian counterparts. These larger APAs were also reported to have similarities with the zona fasciculata (ZF) in the adrenal both from the steroid production profile and the morphology of the cell. We therefore aimed to corroborate these findings by characterizing the APAs from a multi-ethnic Malaysian cohort. The prevalence of KCNJ5 mutations was estimated through targeted DNA sequencing of KCNJ5 in 54 APAs. Confirmation of APA sample acquisition was performed by CYP11B2 immunohistochemistry (IHC) staining. The ZF steroid production profile was based on the ZF enzyme CYP17A1 IHC staining, and ZF cell morphology was based on a high cytoplasm to nucleus ratio. Seventeen (31.5%) APAs studied, harbored a KCNJ5 mutation. No female over-representation was seen in this cohort though females were found to have a higher expression of CYP11B2 than males (p = 0.009; Mann-Whitney U test). Age at adrenalectomy correlated negatively with the percentage of ZF-like cells in the APA (p = 0.01; Spearman's rho) but not with the KCNJ5 genotype. KCNJ5 mutant APAs had a high percentage of ZF-like cells (and high CYP17A1 expression) but so did the wild-type APAs. In summary, prevalence of KCNJ5 mutant APAs in this cohort was similar to other Caucasian cohorts, however, over-representation of females did not occur, which is similar to some studies in Oriental cohorts.

Aldosterone-Producing Adenomas

Mutations in KCNJ5 , ATP1A1 , ATP2B3 , CACNA1D , and CTNNB1 are thought to cause the excessive autonomous aldosterone secretion of aldosterone-producing adenomas (APAs). The histopathology of KCNJ5 mutant APAs, the most common and largest, has been thoroughly investigated and shown to have a zona fasciculata–like composition. This study aims to characterize the histopathologic spectrum of the other genotypes and document the proliferation rate of the different sized APAs. Adrenals from 39 primary aldosteronism patients were immunohistochemically stained for CYP11B2 to confirm diagnosis of an APA. Twenty-eight adenomas had sufficient material for further analysis and were target sequenced at hot spots in the 5 causal genes. Ten adenomas had a KCNJ5 mutation (35.7%), 7 adenomas had an ATP1A1 mutation (25%), and 4 adenomas had a CACNA1D mutation (14.3%). One novel mutation in exon 28 of CACNA1D (V1153G) was identified. The mutation caused a hyperpolarizing shift of the voltage-dependent activation and inactivation and slowed the channel’s inactivation kinetics. Immunohistochemical stainings of CYP17A1 as a zona fasciculata cell marker and Ki67 as a proliferation marker were used. KCNJ5 mutant adenomas showed a strong expression of CYP17A1, whereas ATP1A1 / CACNA1D mutant adenomas had a predominantly negative expression ( P value =1.20×10 −4 ). ATP1A1 / CACNA1D mutant adenomas had twice the nuclei with intense staining of Ki67 than KCNJ5 mutant adenomas (0.7% [0.5%–1.9%] versus 0.4% [0.3%–0.7%]; P value =0.04). Further, 3 adenomas with either an ATP1A1 mutation or a CACNA1D mutation had >30% nuclei with moderate Ki67 staining. In summary, similar to KCNJ5 mutant APAs, ATP1A1 and CACNA1D mutant adenomas have a seemingly specific histopathologic phenotype.