KCNJ5 mutation is a predictor for recovery of endothelial function after adrenalectomy in patients with aldosterone-producing adenoma

The relationship of KCNJ5 mutation with vascular function and vascular structure in aldosterone-producing adenoma (APA) patients before and after adrenalectomy remains unclear. The purpose of this study was to evaluate the influence of KCNJ5 mutation on vascular function and vascular structure in APA and the effects of adrenalectomy on vascular function and vascular structure in APA patients with and those without KCNJ5 mutation. Flow-mediated vasodilation (FMD), nitroglycerine-induced vasodilation (NID), brachial artery intima-media thickness (IMT), and brachial-ankle pulse wave velocity (baPWV) were measured to assess vascular function and vascular structure in 46 APA patients with KCNJ5 mutation and 23 APA patients without KCNJ5 mutation and in 69 matched pairs of patients with essential hypertension (EHT). FMD, NID, brachial IMT and baPVW were evacuated before adrenalectomy and at 12 weeks after adrenalectomy in APA patients with KCNJ5 mutation and APA patients without KCNJ5 mutation. FMD and NID were significantly lower in APA patients than in patients with EHT. There was no significant difference in FMD or NID between patients with and those without KCNJ5 mutation. In APA patients with KCNJ5 mutation, FMD and NID after adrenalectomy were significantly higher than those before adrenalectomy. In APA patients without KCNJ5 mutation, only NID after adrenalectomy was significantly higher than that before adrenalectomy. Endothelial function in APA patients with KCNJ5 mutation was improved by adrenalectomy in the early postoperative period. KCNJ5 mutation is a predictor for early resolution of endothelial function by adrenalectomy. This study was approved by principal authorities and ethical issues in Japan (URL for Clinical Trial: http://www.umin.ac.jp/ctr/index.htm Registration Number for Clinical Trial: UMIN000003409).

Selective activation of PPARα maintains thermogenic capacity of beige adipocytes

Beige adipocytes are inducible thermogenic adipocytes used for anti-obesity treatment. Beige adipocytes rapidly lose their thermogenic capacity once external cues are removed. However, long-term administration of stimulants, such as PPARγ and β-adrenergic receptor agonists, is unsuitable due to various side effects. Here, we reported that PPARα pharmacological activation was the preferred target for maintaining induced beige adipocytes. Pemafibrate used in clinical practice for dyslipidemia was developed as a selective PPARα modulator (SPPARMα). Pemafibrate administration regulated the thermogenic capacity of induced beige adipocytes, repressed body weight gain, and ameliorated impaired glucose tolerance in diet-induced obese mouse models. The transcriptome analysis revealed that the E-twenty-six transcription factor ELK1 acted as a cofactor of PPARα. ELK1 was mobilized to the Ucp1 transcription regulatory region with PPARα and modulated its expression by pemafibrate. These results suggest that selective activation of PPARα by pemafibrate is advantageous to maintain the function of beige adipocytes.

Somatic mutations of CADM1 in aldosterone-producing adenomas and gap junction-dependent regulation of aldosterone production

Aldosterone-producing adenomas (APAs) are the commonest curable cause of hypertension. Most have gain-of-function somatic mutations of ion channels or transporters. Herein we report the discovery, replication and phenotype of mutations in the neuronal cell adhesion gene CADM1. Independent whole exome sequencing of 40 and 81 APAs found intramembranous p.Val380Asp or p.Gly379Asp variants in two patients whose hypertension and periodic primary aldosteronism were cured by adrenalectomy. Replication identified two more APAs with each variant (total, n = 6). The most upregulated gene (10- to 25-fold) in human adrenocortical H295R cells transduced with the mutations (compared to wildtype) was CYP11B2 (aldosterone synthase), and biological rhythms were the most differentially expressed process. CADM1 knockdown or mutation inhibited gap junction (GJ)-permeable dye transfer. GJ blockade by Gap27 increased CYP11B2 similarly to CADM1 mutation. Human adrenal zona glomerulosa (ZG) expression of GJA1 (the main GJ protein) was patchy, and annular GJs (sequelae of GJ communication) were less prominent in CYP11B2-positive micronodules than adjacent ZG. Somatic mutations of CADM1 cause reversible hypertension and reveal a role for GJ communication in suppressing physiological aldosterone production.

A hyperaldosteronism subtypes predictive model using ensemble learning

This study aimed to develop a machine-learning algorithm to diagnose aldosterone-producing adenoma (APA) for predicting APA probabilities. A retrospective cross-sectional analysis of the Japan Rare/Intractable Adrenal Diseases Study dataset was performed using the nationwide PA registry in Japan comprised of 41 centers. Patients treated between January 2006 and December 2019 were included. Forty-six features at screening and 13 features at confirmatory test were used for model development to calculate APA probability. Seven machine-learning programs were combined to develop the ensemble-learning model (ELM), which was externally validated. The strongest predictive factors for APA were serum potassium (s-K) at first visit, s-K after medication, plasma aldosterone concentration, aldosterone-to-renin ratio, and potassium supplementation dose. The average performance of the screening model had an AUC of 0.899; the confirmatory test model had an AUC of 0.913. In the external validation, the AUC was 0.964 in the screening model using an APA probability of 0.17. The clinical findings at screening predicted the diagnosis of APA with high accuracy. This novel algorithm can support the PA practice in primary care settings and prevent potentially curable APA patients from falling outside the PA diagnostic flowchart.

Genetic Risk of Primary Aldosteronism and Its Contribution to Hypertension: A Cross-Ancestry Meta-Analysis of Genome-Wide Association Study

BACKGROUND

Hypertension imposes substantial health and economic burden worldwide. Primary aldosteronism (PA) is one of the most common causes of secondary hypertension, causing cardiovascular events at higher risk compared with essential hypertension. However, the germline genetic contribution to the susceptibility of PA has not been well elucidated.

METHOD

We conducted a genome-wide association analysis of PA in the Japanese population and a cross-ancestry meta-analysis combined with UK Biobank and FinnGen cohorts (816 PA cases and 425 239 controls) to identify genetic variants that contribute to PA susceptibility. We also performed a comparative analysis for the risk of 42 previously established blood pressure-associated variants between PA and hypertension with the adjustment of blood pressure.

RESULTS

In the Japanese genome-wide association study, we identified 10 loci that presented suggestive evidence for the association with the PA risk (P<1.0×10^-6). In the meta-analysis, we identified 5 genome-wide significant loci (1p13, 7p15, 11p15, 12q24, and 13q12; P<5.0×10^-8), including 3 of the suggested loci in the Japanese genome-wide association study. The strongest association was observed at rs3790604 (1p13), an intronic variant of WNT2B (odds ratio, 1.50 [95% CI, 1.33-1.69]; P=5.2×10^-11). We further identified 1 nearly genome-wide significant locus (8q24, CYP11B2), which presented a significant association in the gene-based test (P=7.2×10^-7). Of interest, all of these loci were known to be associated with blood pressure in previous studies, presumably because of the prevalence of PA among individuals with hypertension. This assumption was supported by the observation that they had a significantly higher risk effect on PA than on hypertension. We also revealed that 66.7% of the previously established blood pressure-associated variants had a higher risk effect for PA than for hypertension.

CONCLUSIONS

This study demonstrates the genome-wide evidence for a genetic predisposition to PA susceptibility in the cross-ancestry cohorts and its significant contribution to the genetic background of hypertension. The strongest association with the WNT2B variants reinforces the implication of the Wnt/β-catenin pathway in the PA pathogenesis.

Blood flow in the optic nerve head in patients with primary aldosteronism

PURPOSE

Optic nerve head (ONH) blood flow decrease without changes in intraocular pressure in a possible rat model of retinal ganglion cell loss by systemic administration of aldosterone. To compare the blood flow in the ONH, using laser speckle flowgraphy (LSFG), in healthy eyes and in eyes with primary aldosteronism (PA).

METHODS

The ONH tissue area mean blur rate (MT) was evaluated in this single center, retrospective, cross-sectional study using LSFG. In order to compare the MT between PA patients and normal subjects, mixed-effects models were used, with adjustments made for the mean arterial pressure, disc area, and β-peripapillary atrophy (β-PPA) area. Mixed-effects models were also used to analyze the risk factors affecting the MT.

RESULTS

This study evaluated a total of 29 eyes of 17 PA patients and 61 eyes of 61 normal subjects. There was a significantly lower MT in PA patients (10.8 ± 0.4) as compared to the normal subjects (12.3 ± 0.3) (P = 0.004). The MT was significantly lower in PA patients (10.8 ± 0.6) even after adjusting for the potential confounding factors when compared to normal subjects (12.3 ± 0.3) (P = 0.046). Multivariate mixed-effects model analysis demonstrated that the MT was significantly associated with the PA and β-PPA.

CONCLUSIONS

There was a significantly lower ONH blood flow in PA patients as compared to normal subjects.

Effect of Intraprocedural Cortisol Measurement on ACTH-stimulated Adrenal Vein Sampling in Primary Aldosteronism

Context

Adrenocorticotropin (ACTH) loading is used to increase the success rate of adrenal vein sampling (AVS).

Objective

We aimed to determine the effect of intraprocedural cortisol measurement (ICM) on ACTH-stimulated AVS (AS-AVS) owing to a lack of reliable data on this topic.

Methods

This multicenter, retrospective, observational study took place in 28 tertiary centers in Japan. Among 4057 patients enrolled, 2396 received both basal AVS (B-AVS) and AS-AVS and were divided into 2 groups according to whether ICM was used. The effect of ICM on AS-AVS was measured.

Results

In patients who underwent both AVS procedures, the ICM group had significantly higher success rates for both B-AVS and AS-AVS than the non-ICM group did. However, the probability of failure of AS-AVS after a successful B-AVS and the probability of success of AS-AVS after a failed B-AVS were not significantly different in the 2 groups. For subtype diagnosis, propensity-score matching revealed no significant difference between the 2 groups, and the discrepancy rate between B-AVS and AS-AVS for subtype diagnosis was also not significantly different.

Conclusion

ICM significantly increased the success rate of B-AVS and AS-AVS in protocols in which both AVS procedures were performed and had no effect on subtype diagnosis. However, in protocols in which both AVS procedures were performed, the results suggest ICM may not be necessary when performing AS-AVS if ICM is used only when B-AVS is performed. Our study suggests that ICM during AVS plays an important role and should be recommended.

NFIA determines the cis-effect of genetic variation on Ucp1 expression in murinethermogenic adipocytes

Thermogenic brown and beige adipocytes counteract obesity by enhancing energy dissipation via uncoupling protein-1 (Ucp1). However, the effect of genetic variation on these cells, a major source of disease susceptibility, has been less well studied. Here we examined beige adipocytes from obesity-prone C57BL/6J (B6) and obesity-resistant 129X1/SvJ (129) mouse strains and identified a cis-regulatory variant rs47238345 that is responsible for differential Ucp1 expression. The alternative T allele of rs47238345 at the Ucp1 -12kb enhancer in 129 facilitates the allele-specific binding of nuclear factor I-A (NFIA) to mediate allele-specific enhancer-promoter interaction and Ucp1 transcription. Furthermore, CRISPR-Cas9/Cpf1-mediated single nucleotide polymorphism (SNP) editing of rs47238345 resulted in increased Ucp1 expression. We also identified Lim homeobox protein 8 (Lhx8), whose expression is higher in 129 than in B6, as a trans-acting regulator of Ucp1 in mice and humans. These results demonstrate the cis- and trans-acting effects of genetic variation on Ucp1 expression that underlie phenotypic diversity.

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NFIA in adipocytes determines Ucp1 expression between obesity-prone and -resistant mouse strains

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Allele-specific binding of NFIA at the Ucp1 -12kb enhancer mediates differential Ucp1 expression

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Editing of a SNP at the Ucp1 -12kb enhancer is sufficient to increase Ucp1 in obesity-prone strain

Association of DNA methylation with steroidogenic enzymes in Cushing's adenoma

DNA methylation and demethylation regulate the transcription of genes. DNA methylation-associated gene expression of adrenal steroidogenic enzymes may regulate cortisol production in cortisol-producing adenoma (CPA). We aimed to determine the DNA methylation levels of all genes encoding steroidogenic enzymes involved in CPA. Additionally, the aims were to clarify the DNA methylation-associated gene expression and evaluate the difference of CPA genotype from others using DNA methylation data. Twenty-five adrenal CPA and six nonfunctioning adrenocortical adenoma (NFA) samples were analyzed. RNA sequencing and DNA methylation array were performed. The methylation levels at 118 methylation sites of the genes were investigated, and their methylation and mRNA levels were subsequently integrated. Among all the steroidogenic enzyme genes studied, CYP17A1 gene was mainly found to be hypomethylated in CPA compared to that in NFA, and the Benjamini-Hochberg procedure demonstrated that methylation levels at two sites in the CYP17A1 gene body were statistically significant. PRKACA mutant CPAs predominantly exhibited hypomethylation of CYP17A1 gene compared with the GNAS mutant CPAs. Inverse associations between CYP17A1 methylation in three regions of the gene body and its mRNA levels were observed in the NFAs and CPAs. In applying clustering analysis using CYP17A1 methylation and mRNA levels, CPAs with PRKACA mutation were differentiated from NFAs and CPAs with a GNAS mutation. We demonstrated that CPAs exhibited hypomethylation of the CYP17A1 gene body in CPA, especially in the PRKACA mutant CPAs. Methylation of CYP17A1 gene may influence its transcription levels.

Association of cardiovascular disease risk and changes in renin levels by mineralocorticoid receptor antagonists in patients with primary aldosteronism

A recent report stated that patients with primary aldosteronism who remain renin suppressed during mineralocorticoid receptor antagonist treatment might have a higher risk of developing cardiovascular disease than those with unsuppressed renin activity. We retrospectively investigated the incidence of composite cardiovascular disease and risk factors for cardiovascular disease in 1115 Japanese patients with primary aldosteronism treated with mineralocorticoid receptor antagonists. The median follow-up period was 3.0 years, and the incidence of cardiovascular events was very low (2.1%) throughout 5 years of follow-up. Changes in plasma renin activity from before to after mineralocorticoid receptor antagonist treatment were divided into three groups based on tertile, low, intermediate, and high plasma renin activity change groups, with incidences of cardiovascular disease events of 2.1%, 0.5%, and 3.7%, respectively. Multivariate Cox regression analysis revealed age (adjusted hazard ratio, 1.07; 95% confidence interval, [1.02-1.12]) and body mass index (adjusted hazard ratio, 1.13 [1.04-1.23]) as independent risk factors for cardiovascular disease. The high plasma renin activity change group had significantly higher cardiovascular disease risk with mineralocorticoid receptor antagonist treatment than the intermediate plasma renin activity change group (adjusted hazard ratio, 5.71 [1.28-25.5]). These data suggest that a high change in renin level after mineralocorticoid receptor antagonist treatment may not necessarily predict a better prognosis of cardiovascular disease in patients with primary aldosteronism.

Hypomethylation associated vitamin D receptor expression in ATP1A1 mutant aldosterone-producing adenoma

DNA methylation alteration is tissue-specific and play a pivotal role in regulating gene transcription during cell proliferation and survival. We aimed to detect genes regulated by DNA methylation, and then investigated whether the gene influenced cell proliferation or survival in adrenal cells. DNA methylation and qPCR analyses were performed in nonfunctioning adrenocortical adenoma (NFA, n = 12) and aldosterone-producing adenoma (APA, n = 35) samples. The VDR gene promoter was markedly hypomethylated in APA with ATP1A1 mutation, and the promoter methylation levels showed a significant inverse association with the transcripts in APA. ATP1A1 mutation led to VDR transcription in HAC15 cells, and VDR suppression abrogated ATP1A1 mutation-mediated cell proliferation in HAC15 cells. We demonstrated that APA with ATP1A1 mutation showed entire hypomethylation in the VDR promoter and abundant VDR mRNA and protein expression. VDR suppression abrogated ATP1A1 mutation-mediated cell proliferation in HAC15 cells. Abundant VDR expression would be essential for ATP1A1 mutation-mediated cell proliferation.

Genotype-specific cortisol production associated with Cushing's syndrome adenoma with PRKACA mutations

The intracellular molecular mechanisms underlying the genotype of cortisol-producing adenoma (CPA) have not been fully determined. We analyzed gene expressions in CPA and the human adrenocortical cell line (HAC15 cells) with PRKACA mutation. Clustering analysis using a gene set associated with responses to cAMP revealed the possible differences between PRKACA mutant CPAs and GNAS and CTNNB1 mutant CPAs. The levels of STAR, CYP11A1, CYP17A1, CYP21A2, and FDX1 transcripts and cortisol levels per unit area in PRKACA mutant CPAs were significantly higher than those in GNAS mutant CPAs. PRKACA mutations led to an increase in steroidogenic enzyme expression and cortisol production in HAC15 cells. Transcriptome analysis revealed differences between PRKACA mutant CPAs and GNAS and CTNNB1 mutant CPAs. Cortisol production in PRKACA mutant CPAs is increased by the cAMP-PKA signaling pathway-mediated upregulation of steroidogenic enzymes transcription. The intracellular molecular mechanisms underlying these processes would be notably important in PRKACA mutant CPAs.

Subtype-specific trends in the clinical picture of primary aldosteronism over a 13-year period

OBJECTIVE

Primary aldosteronism has two main clinically and biologically distinct subtypes: unilateral aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH). We aimed to evaluate the changes of each subtype's clinical characteristics over a 13-year period.

METHODS

This retrospective study involved time-trend analyses to identify changes in the clinical features of APA and BAH at diagnosis (2006-2018). A nationwide database from 41 Japanese referral centers was searched, which identified 2804 primary aldosteronism patients with complete baseline information and adrenal venous sampling (AVS) data.

RESULTS

The proportion of patients with APA decreased from 51% in 2006-2009 to 22% in 2016-2018. Among the 1634 patients with BAH, trend analyses revealed decreases in hypertension duration (median 7--3 years; P < 0.01) and hypokalemia prevalence (18--11%; P < 0.01). However, among the 952 patients with APA, there were no significant changes in hypertension duration (median 8 years) and hypokalemia prevalence (overall 70%). Furthermore, the APA group had a trend towards increased use of multiple hypertensive drugs at diagnosis (30--43%; P < 0.01). When subtypes were reclassified according to the precosyntropin stimulation AVS data, APA patients tended to be diagnosed earlier and at milder forms, consistent with the trend in overall primary aldosteronism patients.

CONCLUSION

During 2006-2018, we identified marked subtype-specific trends in the clinical findings at the diagnosis of primary aldosteronism. Our results suggested that the emphasis on the implementing cosyntropin stimulation during AVS might lead to under-identification of APA, especially in patients with mild or early cases.

Renal Injuries in Primary Aldosteronism: Quantitative Histopathological Analysis of 19 Patients With Primary Adosteronism

[Figure: see text].

Association of aldosterone and blood pressure with the risk for cardiovascular events after treatments in primary aldosteronism

BACKGROUND AND AIMS

We used a dataset from a Japanese nationwide registry of patients with primary aldosteronism, to determine which of the parameters of hyperaldosteronism and blood pressure before or after treatments for primary aldosteronism (i.e., surgical adrenalectomy or a medication treatment) are important in terms of cardiovascular prognosis.

METHODS

We assessed whether plasma aldosterone-to-renin ratio and pulse pressure levels before treatment and 6 months after treatment were associated with composite cardiovascular disease events during the 5-year follow-up period.

RESULTS

The cohort included 1987 patients (mean age was 53.2 years, 52.0% were female, 37.2% had undergone surgical treatment, and the remainder had been treated with mineralocorticoid receptor antagonists). In the Cox proportional hazard model, the covariate-adjusted hazard ratio (95% confidence interval) for the composite cardiovascular disease events risk for each one-standard-deviation increase in the aldosterone-to-renin ratio or pulse pressure before treatment, those after treatment, or the duration of hypertension were 1.24 (1.05, 1.48), 0.74 (0.54, 1.02), and 1.07 (0.79, 1.44), 1.43 (1.07, 1.92), and 1.52 (1.19, 1.95), respectively. Patients with a high pre-treatment aldosterone-to-renin ratio of more than 603 and a large post-treatment pulse pressure of more than 49 mmHg showed approximately three-fold higher hazard ratios for cardiovascular events risk compared to those with a lower aldosterone-to-renin ratio and smaller pulse pressure.

CONCLUSIONS

Higher aldosterone-to-renin ratio before treatments, higher pulse pressure after treatments, and longer duration of hypertension were prognostic factors for cardiovascular diseases. Early intervention may be important for preventing cardiovascular disease among patients with primary aldosteronism.

Variation in plasma glucagon levels according to obesity status in Japanese Americans with normal glucose tolerance

Japanese Americans living in the United States are genetically identical to Japanese people, but have undergone a rapid and intense westernization of their lifestyle. This study investigated variability in glucagon secretion after glucose loading among Japanese Americans with normal glucose tolerance (NGT) according to obesity status. The 75-g oral glucose tolerance test (OGTT) was performed for 138 Japanese Americans (aged 40-75 years) living in Los Angeles. Plasma glucagon levels measured using the sandwich enzyme-linked immunosorbent assay were compared according to body mass index (BMI) categories among 119 individuals with NGT. The individuals were classified into three categories according to their BMI values: <22 kg/m² (n = 37), 22-24.9 kg/m² (n = 46), and ≥25 kg/m² (n = 36). Fasting plasma glucagon levels and glucagon-area under the curve levels during the OGTT were the highest in the BMI ≥25 kg/m² group. Fasting glucagon levels were correlated with BMI (r = 0.399, p < 0.001), fasting insulin levels (r = 0.275, p = 0.003) and the homeostasis model assessment-insulin resistance (r = 0.262, p = 0.004). In conclusion, our findings suggest that fasting hyperglucagonemia is associated with obesity and insulin resistance even during the NGT stage in the Japanese American population.

Should Adrenal Venous Sampling Be Performed in PA Patients Without Apparent Adrenal Tumors?

INTRODUCTION

Some aldosterone-producing micro-adenomas cannot be detected through image inspection. Therefore, adrenal venous sampling (AVS) is often performed, even in primary aldosteronism (PA) patients who have no apparent adrenal tumors (ATs) on imaging. In most of these cases, however, the PA is bilateral.

OBJECTIVE

To clarify the clinical need for AVS in PA patients without apparent ATs, taking into consideration the rates of adrenalectomy.

METHODS

This is a retrospective cross-sectional study assessing 1586 PA patients without apparent ATs in the multicenter Japan PA study (JPAS). We analyzed which parameters could be used to distinguish unilateral PA patients without apparent ATs from bilateral patients. We also analyzed the prevalences of adrenalectomy in unilateral PA patients.

RESULTS

The unilateral subtype without an apparent AT was diagnosed in 200 (12.6%) of 1586 PA patients. Being young and female with a short hypertension duration, normokalemia, low creatinine level, low plasma aldosterone concentration, and low aldosterone-to-renin ratio (ARR) was significantly more common in bilateral than unilateral PA patients. If PA patients without apparent ATs were female and normokalemic with a low ARR (<560 pg/ml per ng/ml/h), the rate of unilateral PA was only 5 (1.1%) out of 444. Moreover, 77 (38.5%) of the 200 did not receive adrenalectomy, despite being diagnosed with the unilateral subtype based on AVS.

CONCLUSION

The low prevalence of the unilateral subtype in PA patients without apparent ATs suggests AVS is not indicated for all of these patients. AVS could be skipped in female normokalemic PA patients without apparent ATs if their ARRs are not high. However, AVS should be considered for male hypokalemic PA patients with high ARRs because the rates of the unilateral subtype are high in these patients.

Sex Differences in Renal Outcomes After Medical Treatment for Bilateral Primary Aldosteronism

A higher incidence of bilateral primary aldosteronism in women is reported. Treatment of bilateral primary aldosteronism usually involves mineralocorticoid receptor antagonists. However, the impact of sex on renal outcomes is unknown. We compared renal outcomes between the sexes after mineralocorticoid receptor antagonist initiation by analyzing data obtained from 415 female and 313 male patients with bilateral primary aldosteronism who were treated with spironolactone or eplerenone in the JPAS (Japan Primary Aldosteronism Study). Over the course of 5 years, the temporal reduction in the estimated glomerular filtration rate was greater in women than in men (P<0.001). Systolic blood pressure levels were equal between the sexes, despite higher doses of antihypertensive drugs in men. The mean of the annual decline in estimated glomerular filtration rate during what we termed the late phase, or 6 to 60 months after mineralocorticoid receptor antagonist initiation, was larger in women than in men after adjusting for patient characteristics (-1.33 mL/min per 1.73 m² per year versus -1.04 mL/min per 1.73 m² per year, P<0.01). Female sex was a significant predictor of greater annual decline during the late phase in patients taking spironolactone but not in those taking eplerenone. Spironolactone use and diabetes were independent predictors of a greater annual decline in estimated glomerular filtration rate during the late phase in women. These findings suggest that female sex is associated with poorer renal outcomes in patients receiving mineralocorticoid receptor antagonist for bilateral primary aldosteronism.

A Comparison of Adrenalectomy and Eplerenone on Vascular Function in Patients with Aldosterone-producing Adenoma

CONTEXT

It remains unclear whether adrenalectomy has more beneficial effects than treatment with a mineralocorticoid receptor antagonist on vascular function in patients with aldosterone-producing adenoma (APA).

OBJECTIVE

The aim of this study was to compare the effects of adrenalectomy and treatment with eplerenone on vascular function in patients with APA.

DESIGN, SETTING, AND PATIENTS

Flow-mediated vasodilation (FMD), as an index of endothelium-dependent vasodilation, and nitroglycerine-induced vasodilation (NID), as an index of endothelium-independent vasodilation, were measured to assess vascular function before and after a 3-month treatment with eplerenone and at 3 months after adrenalectomy in 23 patients with APA.

RESULTS

Flow-mediated vasodilation and NID after adrenalectomy were significantly higher than those before treatment with eplerenone (5.4 ± 2.6% vs 2.7 ± 1.9% and 14.8 ± 4.7% vs 9.6 ± 4.6%, P < 0.01, respectively) and those after treatment with eplerenone (5.4 ± 2.6% vs 3.1 ± 2.3% and 14.8 ± 4.7% vs 11.0 ± 5.3%, P < 0.01 and P = 0.03, respectively), while treatment with eplerenone did not alter FMD and NID compared with those before treatment with eplerenone. After adrenalectomy, the increase in FMD and NID were significantly correlated with a decrease in plasma aldosterone concentration and a decrease in the aldosterone-renin ratio. There were no significant relationships between FMD and changes in other parameters or between NID and changes in other parameters.

CONCLUSIONS

Adrenalectomy, but not treatment with eplerenone, improved vascular function in patients with APA. Adrenalectomy may be more effective than treatment with eplerenone for reducing the incidence of future cardiovascular events in patients with APA. Clinical Trial Information: URL for the clinical trial: http://UMIN; Registration Number for the clinical trial: UMIN000003409.

The landscape of molecular mechanism for aldosterone production in aldosterone-producing adenoma

Primary aldosteronism is the most common form of secondary hypertension with a prevalence of 5-10% in hypertensive patients. Aldosterone-producing adenoma (APA) is a subtype of primary aldosteronism, and somatic mutations in KCNJ5, ATP1A1, ATP2B3, CACNA1D, CLCN2, or CTNNB1 were identified and recognized to drive aldosterone production and/or contribute to tumorigenesis in APA. Mutations of KCNJ5, ATP1A1, ATP2B3, CACNA1D, and CLCN2 are known to activate calcium signaling, and its activation potentiate CYP11B2 (aldosterone synthesis) transcription in adrenal cells. Transcriptome analyses combined with bioinformatics using APA samples were conductive for each gene mutation mediated pivotal pathway, gene ontology, and clustering. Several important intracellular molecules in increase aldosterone production were detected by transcriptome analysis, and additional functional analyses demonstrated intracellular molecular mechanisms of aldosterone production which focused on calcium signal, CYP11B2 transcription and translation. Furthermore, DNA methylation analysis revealed that promoter region of CYP11B2 was entirely hypomethylated, but that of other steroidogenic enzymes were not in APA. Integration of transcriptome and DNA methylome analysis clarified some DNA methylation associated gene expression, and the transcripts have a role for aldosterone production. In this article, we reviewed the intracellular molecular mechanisms of aldosterone production in APA, and discussed future challenges for basic studies leading to clinical practice.

Angiotensin-converting enzyme 2 expression is not induced by the renin-angiotensin system in the lung

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has developed into a pandemic with significant morbidity and mortality. SARS-CoV-2 has been reported to invade lung epithelium via the angiotensin-converting enzyme 2 (ACE2) receptor using its glycosylated cell surface spike protein [1]. ACE2 expression in the heart and kidney is regulated by the renin–angiotensin system (RAS), especially angiotensin II (A-II), which is catalysed from angiotensin I (A-I) by angiotensin-converting enzyme (ACE) [2]. In a cohort study in the early period of the COVID-19 outbreak in Wuhan in China, hypertension was found in 30% of the patients and was identified as the most common comorbidity [3]. It has recently been reported that RAS inhibitors are not associated with the severity of COVID-19 in a meta-analysis that included nine studies comprising 3936 patients with hypertension and COVID-19 [4]. The most serious concerns for the use of RAS inhibitors may be related to their role in development of or exacerbation of COVID-19, as suggested in a recent review by Ingrahamet al. [5]. However, the alteration in ACE2 expression in pulmonary cells has not been studied.

Pulmonary expression of angiotensin-converting enzyme 2, which is a receptor of severe acute respiratory syndrome coronavirus 2, is not regulated by angiotensin II or renin–angiotensin system inhibitors #COVID19https://bit.ly/3fkopuO

A Case of Isolated Adrenocorticotropic Hormone Deficiency Caused by Pembrolizumab

Pembrolizumab (Keytruda®) is an anti-programmed cell death 1-specific monoclonal antibody that has become the standard second-line chemotherapy for unresectable advanced microsatellite instability-high colorectal cancer. Several immune-related adverse events (irAEs), particularly endocrinopathy, are linked to the administration of pembrolizumab. We report here a case of pembrolizumab-induced isolated adrenocorticotropic hormone deficiency in a patient with metastatic colon cancer. A 65-year-old woman visited our hospital for complaints of fatigue with a recent history of primary resection of cecal mucinous cancer and hepatectomy for liver metastasis 3 years ago. Peritoneal dissemination was detected 2 years after surgery. Several chemotherapeutic regimens of cytotoxic and molecular targeted drugs were administered; however, the metastases progressed gradually. Pembrolizumab monotherapy was started because of resistance to treatment. After 2 cycles of pembrolizumab, the patient was severely fatigued. Laboratory data demonstrated that the cortisol level was extremely low. All the other values were within the normal range. Magnetic resonance imaging indicated no mass in the pituitary gland. From multiple tolerance tests, we diagnosed isolated adrenocorticotropic hormone deficiency caused by pembrolizumab. The patient's symptoms improved promptly with cortisol treatment. An abdominal contrast-enhanced computed tomography scan after 5 cycles of pembrolizumab demonstrated that the size of the peritoneal dissemination remained unchanged. However, her serum level of carcinoembryonic antigen had decreased to normal levels. Endocrine disorders are very rarely seen as irAEs. Careful laboratory data follow-up is required to inhibit the progression of severe endocrine disorders.

Attempts to develop an enzyme converting DHIV to KIV

Dihydroxy-acid dehydratase (DHAD) catalyzes the dehydration of R-2,3-dihydroxyisovalerate (DHIV) to 2-ketoisovalerate (KIV) using an Fe-S cluster as a cofactor, which is sensitive to oxidation and expensive to synthesize. In contrast, sugar acid dehydratases catalyze the same chemical reactions using a magnesium ion. Here, we attempted to substitute the high-cost DHAD with a cost-efficient engineered sugar acid dehydratase using computational protein design (CPD). First, we tried without success to modify the binding pocket of a sugar acid dehydratase to accommodate the smaller, more hydrophobic DHIV. Then, we used a chemically activated substrate analog to react with sugar acid dehydratases or other enolase superfamily enzymes. Mandelate racemase from Pseudomonas putida (PpManR) and the putative sugar acid dehydratase from Salmonella typhimurium (StPutD) showed beta-elimination activity towards chlorolactate (CLD). CPD combined with medium-throughput selection improved the PpManR kcat/KM for CLD by four-fold. However, these enzyme variants did not show dehydration activity towards DHIV. Lastly, assuming phosphorylation could also be a good activation mechanism, we found that mevalonate-3-kinase (M3K) from Picrophilus torridus (PtM3K) exhibited adenosine triphosphate (ATP) hydrolysis activity when mixed with DHIV, indicating phosphorylation activity towards DHIV. Engineering PpManR or StPutD to accept 3-phospho-DHIV as a substrate was performed, but no variants with the desired activity were obtained.

Endoplasmic Reticulum Chaperone Calmegin Is Upregulated in Aldosterone-Producing Adenoma and Associates With Aldosterone Production

The endoplasmic reticulum (ER) plays a pivotal role in syntheses of proteins and steroid hormones and regulation of intracellular Ca²⁺ level. We aimed to investigate ER-associated genes in aldosterone-producing adenomas (APAs) and clarify their effect on aldosterone production. Microarray analysis targeting 288 ER-associated genes was conducted using nonfunctioning adrenocortical adenomas (n=5) and APAs (n=19). Immunohistochemistry and quantitative polymerase chain reaction analyses were performed with 13 nonfunctioning adrenocortical adenoma and 48 APA samples. Functional studies were performed with human adrenocortical carcinoma (HAC15) cells, some of which were genetically modified using lentiviruses. The ER chaperone calmegin (CLGN) was the most highly expressed ER-associated gene in APAs relative to nonfunctioning adrenocortical adenomas. Analysis with quantitative polymerase chain reaction revealed CLGN to be 9.5-fold upregulated in APAs relative to nonfunctioning adrenocortical adenomas. There were no differences among different APA genotypes affecting aldosterone production. Immunohistochemistry analysis revealed that CLGN was strongly expressed in APAs and aldosterone-producing cell clusters. Angiotensin II stimulation or KCNJ5 T158A overexpression in HAC15 cells did not affect CLGN mRNA levels. CLGN overexpression in HAC15 cells increased aldosterone levels but did not stimulate CYP11B2 mRNA levels. Pathway and gene ontology analyses using RNA sequencing results showed that tRNA aminoacyl metabolism was the most enriched pathway in CLGN-overexpressing cells. CYP11B2 (aldosterone synthase) and HSD3B2 (3 beta-hydroxysteroid dehydrogenase/delta 5->4-isomerase type 2) protein expression were more abundant in CLGN-overexpressing cells. CLGN knockdown using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9) method in HAC15 cells that carry the KCNJ5 mutation did not affect aldosterone production. To summarize, CLGN was upregulated and associated with aldosterone production via translational regulation of CYP11B2 in APAs.

Elevated Plasma Renin Activity Caused by Accelerated-malignant Hypertension in a Patient with Aldosterone-producing Adenoma Complicated with Renal Insufficiency

During the malignant phase of hypertension in patients with primary aldosteronism complicated with severe renal failure, the plasma renin activity may markedly increase with a false negative screening result for primary aldosteronism, thus potentially leading to a missed diagnosis of primary aldosteronism. We herein report the case of 37-year-old man who presented with accelerated-malignant hypertension complicated with severe renal insufficiency. The plasma renin activity was markedly increased in the malignant phase of hypertension, which were atypical results for primary aldosteronism. However, a plain abdominal computed tomography scan revealed a left adrenal nodule, which was diagnosed as aldosterone-producing adenoma by adrenal venous sampling.

Alteration of gut microbiota by a Westernized lifestyle and its correlation with insulin resistance in non-diabetic Japanese men

AIMS/INTRODUCTION

The severity of insulin resistance is higher in Japanese-American people with American lifestyles than in native Japanese people with Japanese lifestyles. Recently, the role of gut microbiota in the control of host metabolic homeostasis and organ physiology has been recognized. In addition, gut microbiota alterations have been suggested to contribute to pathogenesis of insulin resistance. The principle aim of the present study was to evaluate the impact of a Westernized lifestyle on the gut microbiota of Japanese-Americans versus native Japanese, and its correlation with insulin resistance.

MATERIALS AND METHODS

A total of 14 native Japanese men living in Hiroshima, Japan, and 14 Japanese-American men living in Los Angeles, USA, were included. A 75-g oral glucose tolerance test was carried out for all participants to assess their glucose tolerance, and normal glucose tolerance was observed. We compared the insulin response with oral glucose load, the Matsuda Index, and the composition of the gut microbiota between the native Japanese and Japanese-American men.

RESULTS

Japanese-American men showed higher area under the curve values for serum insulin concentrations during the oral glucose tolerance test and lower Matsuda Index than native Japanese men. Gut microbiota composition of the Japanese-American men was different; in particular, they showed a relatively lower abundance of Odoribacter than native Japanese men. The ratio between relative abundance of Odoribacter and Matsuda Index was positively correlated between the two groups.

CONCLUSIONS

Our findings suggest that Westernized lifestyles alter gut microbiota, and its alteration might induce insulin resistance in non-diabetic Japanese men.

Associations of nutrient intakes with obesity and diabetes mellitus in the longitudinal medical surveys of Japanese Americans

AIMS/INTRODUCTION

Our previous survey of two Japanese populations, with different lifestyles but identical genetic dispositions, showed that Japanese Americans had different dietary intakes and higher prevalences of obesity and diabetes mellitus, compared with the native Japanese population. The present study examined whether Westernized dietary habits could affect the development of obesity or diabetes.

MATERIALS AND METHODS

This study included 765 individuals with normal glucose tolerance at baseline medical examinations (1986 or 1989 in Los Angeles and in 1988 or 1992 in Hawaii) who subsequently completed follow-up medical examinations several years later. The participants were categorized at baseline as "lean" (576 individuals, body mass index of <25 kg/m2 ) or "obese" (189 individuals, body mass index of ≥25 kg/m2 ). Nutrient intakes were analyzed for associations with the development of obesity or diabetes using Cox's proportional hazard model.

RESULTS

A total of 41 lean participants developed diabetes, which was not associated with any nutrient intakes (mean follow up 10.8 ± 6.6 years). A total of 36 obese participants developed diabetes, which was positively associated with intakes of animal protein, animal fat and saturated fatty acid (mean follow up 10.7 ± 6.3 years). A total of 85 lean participants became obese, which was positively associated with intakes of simple carbohydrates, sugar and fructose, as well as inversely associated with intakes of vegetable protein and complex carbohydrates (mean follow up 10.4 ± 6.5 years).

CONCLUSIONS

In the Japanese Americans, different nutrient intakes affected the development of obesity and diabetes. Furthermore, the associations of nutrient intakes with diabetes development varied according to the presence or absence of obesity.

Angiotensin 1-7 suppresses angiotensin II mediated aldosterone production via JAK/STAT signaling inhibition

Angiotensin 1-7 (Ang 1-7), which is a protein cleaved from angiotensin II (A-II), binds to the MAS receptor. Ang 1-7 has been demonstrated to exert protective effects against A-II-mediated cardiac, atherosclerotic, and renal damages. The aims of our study were to demonstrate the inhibitory role of Ang 1-7 in A-II-mediated aldosterone production by interacting with the MAS receptor in human adrenocortical carcinoma (HAC15) cells, and clarify the intracellular signaling mechanisms underlying the inhibition of aldosterone production by Ang 1-7. Ang 1-7 significantly suppressed A-II-stimulated aldosterone production, and partially abrogated A-II-induced upregulation of CYP11B2 expression. Treatment with a selective Ang 1-7 antagonist abrogated Ang 1-7-mediated inhibition of aldosterone production in HAC15 cells. Incubation of A-II-treated HAC15 cells with conditioned medium containing Ang 1-7 was demonstrated to suppress A-II-mediated aldosterone production and CYP11B2 expression. Proteomic analysis showed that Ang 1-7 predominantly inhibited the phosphorylation of JAK-STAT proteins in A-II stimulated HAC15 cells. Treatment of HAC15 cells with a STAT3 inhibitor partially but significantly repressed A-II-mediated aldosterone production by 63.2%. Similarly, treatment with a STAT5 inhibitor significantly abrogated A-II-stimulated aldosterone production in HAC15 cells by 60.7%. In conclusion, we demonstrated that Ang 1-7 negatively regulates A-II-mediated aldosterone production, and the observed inhibition of aldosterone production was associated with JAK/STAT signaling in human adrenal cells. Therefore, activation of Ang 1-7 or stimulation of the MAS receptor, which inhibits aldosterone production, is a promising therapeutic approach for the prevention of cardiovascular events that can directly affect the target organs.

Measurement of midnight ACTH levels is useful for the evaluation of midnight cortisol levels

OBJECTIVE

Elevated midnight cortisol levels induced by non-suppressed ACTH levels may lead to false-positive results for hypercortisolism in patients with adrenal incidentaloma. We investigated whether plasma ACTH-associated high midnight serum cortisol levels are correlated with other endocrinological findings with respect to hypothalamic-pituitaryadrenal function or hypercortisolism status.

METHODS

Two-hundred-forty-six patients with adrenocortical adenoma were evaluated via measurements of midnight ACTH and cortisol levels, a 1-mg dexamethasone suppression test (DST), and a cosyntropin-releasing hormone (CRH) stimulation test. Patients were divided into four groups according to their midnight plasma ACTH levels.

RESULTS

The groups with higher midnight ACTH levels had significantly higher basal ACTH levels. A positive relationship was observed between midnight serum cortisol and serum cortisol in the 1-mg DST for all groups; stronger associations were observed in the group with lower midnight ACTH. In the CRH test, peak, delta, and sigma ACTH had significant inverse relationships with midnight cortisol levels in the lowest and second lowest midnight ACTH groups. Patients with midnight cortisol levels >3.5 μg/dL were further divided into two groups according to whether their midnight plasma ACTH levels were below or above 10.0 pg/mL. There were significantly fewer patients with hypercortisolism in the higher ACTH group; midnight serum cortisol levels were associated with hypercortisolism only in the lower ACTH group.

CONCLUSION

We demonstrated that midnight ACTH-associated cortisol values were not correlated with other endocrinological findings or hypercortisolism state. Measurement of midnight ACTH levels is important, and careful evaluation is needed for patients with higher midnight ACTH levels.

Microvascular endothelial function is impaired in patients with idiopathic hyperaldosteronism

The aims were to evaluate the relationship between idiopathic hyperaldosteronism (IHA) and grade of vascular function in the macrovasculature and microvasculature. Vascular function, including reactive hyperemia index (RIH), flow-mediated vasodilation (FMD), and nitroglycerine-induced vasodilation (NID) were evaluated in 52 patients with IHA, 53 patients with aldosterone-producing adenoma (APA), and 52 age-, sex-, and blood pressure-matched patients with essential hypertension (EHT). Log RHI was lower in the IHA and APA groups than in the EHT group (0.54 ± 0.25 and 0.55 ± 0.23 versus 0.79 ± 0.28; P < 0.01, respectively). FMD was lower in the APA group than in the EHT group (3.4 ± 2.1% versus 4.8 ± 2.8%; P = 0.02), whereas there was no significant difference in FMD between the IHA and the APA and EHT groups. NID was lower in the APA group than in the EHT group (10.0 ± 4.5% versus 12.5 ± 5.7%; P = 0.03), whereas there was no significant difference in NID between the IHA, APA, and EHT groups. Multiple regression analysis revealed an association of log RHI with plasma aldosterone concentration (t = -2.24; P = 0.03) and an association of FMD with plasma aldosterone concentration (t = -3.07; P < 0.01). Microvascular endothelial function was impaired in patients with IHA compared with that in patients with EHT.

Purkinje Cell Protein 4 Expression Is Associated With DNA Methylation Status in Aldosterone-Producing Adenoma

CONTEXT

Aldosterone production is stimulated by activation of calcium signaling in aldosterone-producing adenomas (APAs), and epigenetic factors such as DNA methylation may be associated with the expression of genes involved in aldosterone regulation.

OBJECTIVE

Our aim was to investigate the DNA methylation of genes related to calcium signaling cascades in APAs and the association of mutations in genes linked to APAs with DNA methylation levels.

METHODS

Nonfunctioning adrenocortical adenoma (n = 12) and APA (n = 35) samples were analyzed. The KCNJ5 T158A mutation was introduced into human adrenocortical cell lines (HAC15 cells) using lentiviral delivery. DNA methylation array analysis was conducted using adrenal tumor samples and HAC15 cells.

RESULTS

The Purkinje cell protein 4 (PCP4) gene was one of the most hypomethylated in APAs. DNA methylation levels in two sites of PCP4 showed a significant inverse correlation with messenger RNA expression in adrenal tumors. Bioinformatics and multiple regression analysis revealed that CCAAT/enhancer binding protein alpha (CEBPA) may bind to the methylation site of the PCP4 promoter. According to chromatin immunoprecipitation assay, CEBPA was bound to the PCP4 hypomethylated region by chromatin immunoprecipitation assay. There were no significant differences in PCP4 methylation levels among APA genotypes. Moreover, KCNJ5 T158A did not influence PCP4 methylation levels in HAC15 cells.

CONCLUSIONS

We showed that the PCP4 promoter was one of the most hypomethylated in APAs and that PCP4 transcription may be associated with demethylation as well as with CEBPA in APAs. KCNJ5 mutations known to result in aldosterone overproduction were not related to PCP4 methylation in either clinical or in vitro studies.

Aberrant G protein-receptor expression is associated with DNA methylation in aldosterone-producing adenoma

This study aimed to evaluate the methylation levels of G protein-coupled receptor (GPCR) related genes and the effects of methylation on mRNA expression levels in aldosterone-producing adenoma (APA). DNA methylation array and transcriptome analysis were applied in non-functioning adrenocortical adenoma (NFA) and APA. We investigated 192 GPCR-related genes and found hypo-methylation in the promoter region of 66 of these genes in APA. An integration study between microarray and methylation analysis revealed that HTR4, MC2R, TACR1, GRM3, and PTGER1 showed hypo-methylation and up-regulation of mRNA in APA. qPCR analysis showed that HTR4 and PTGER1 expression was 9.3-fold and 6.6-fold higher in APAs than in NFAs, respectively, whereas expression of the other genes was not different between the groups. Methylation of HTR4 and PTGER1 at positions -229 and -666 from the transcription start site, respectively, showed a significant inverse correlation with their mRNA levels. Methylation levels were not associated with KCNJ5 or ATP1A1 mutations in human adrenal samples. We demonstrated an increased incidence of CpG island demethylation of GPCR-related gene in APA. The expression of two receptors, HTR4 and PTGER1, showed a strong association with DNA methylation.

Calneuron 1 Increased Ca2+ in the Endoplasmic Reticulum and Aldosterone Production in Aldosterone-Producing Adenoma

Aldosterone production is initiated by angiotensin II stimulation and activation of intracellular Ca²⁺ signaling. In aldosterone-producing adenoma (APA) cells, the activation of intracellular Ca²⁺ signaling is independent of the renin-angiotensin-aldosterone systems. The purpose of our study was to clarify molecular mechanisms of aldosterone production related to Ca²⁺ signaling. Transcriptome analysis revealed that the CALN1 gene encoding calneuron 1 had the strongest correlation with CYP11B2 (aldosterone synthase) among genes encoding Ca²⁺-binding proteins in APA. CALN1 modulation and synthetic or fluorescent compounds were used for functional studies in human adrenocortical carcinoma (HAC15) cells. CALN1 expression was 4.4-fold higher in APAs than nonfunctioning adrenocortical adenomas. CALN1 expression colocalized with CYP11B2 expression as investigated using immunohistochemistry in APA and zona glomerulosa of male rats fed by a low-salt diet. CALN1 expression was detected in the endoplasmic reticulum (ER) by using GFP-fused CALN1, CellLight ER-RFP, and the corresponding antibodies. CALN1-overexpressing HAC15 cells showed increased Ca²⁺ in the ER and cytosol fluorescence-based studies. Aldosterone production was potentiated in HAC15 cells by CALN1 expression, and dose-responsive inhibition with TMB-8 showed that CALN1-mediated Ca²⁺ storage in ER involved sarcoendoplasmic reticulum calcium transport ATPase. The silencing of CALN1 decreased Ca²⁺ in ER, and abrogated angiotensin II- or KCNJ5 T158A-mediated aldosterone production in HAC15 cells. Increased CALN1 expression in APA was associated with elevated Ca²⁺ storage in ER and aldosterone overproduction. Suppression of CALN1 expression prevented angiotensin II- or KCNJ5 T158A-mediated aldosterone production in HAC15 cells, suggesting that CALN1 is a potential therapeutic target for excess aldosterone production.

Westernization of lifestyle affects quantitative and qualitative changes in adiponectin

Background

Although Japanese–Americans and native Japanese share the same genetic predispositions, they live different lifestyles, resulting in insulin resistance in Japanese–Americans. We investigated whether the quantitative and qualitative changes in adiponectin (APN) due to differences in lifestyle contribute to the development of insulin resistance.

Methods

We evaluated 325 native Japanese in Hiroshima, Japan and 304 Japanese–Americans in Los Angeles, the United States, who were aged between 30 and 70 years and underwent medical examinations between 2009 and 2010. All participants underwent a 75-g oral glucose tolerance test (OGTT) to assess their glucose tolerance. The insulin response to oral glucose load, the Matsuda index, total APN levels, and C1q-APN/total-APN ratios were compared between native Japanese and Japanese–Americans.

Results

Compared with the native Japanese, the Japanese–Americans had significantly lower Matsuda index and higher area under the curve values for serum insulin concentration during OGTT in the normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) groups, but not in the diabetes mellitus (DM) group. Furthermore, the Japanese–Americans had significantly lower total APN levels and higher C1q-APN/total-APN ratios than the native Japanese in the NGT and IGT groups, but not in the DM group.

Conclusions

This study suggested that, in Japanese people, the westernization of their lifestyle might affect quantitative and qualitative changes in APN and induce insulin resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0565-z) contains supplementary material, which is available to authorized users.

Association between Serum Elaidic Acid Concentration and Insulin Resistance in Two Japanese Cohorts with Different Lifestyles

Aim: Many cohort studies have shown that increased trans fatty acid (TFA) intake increases the risk of developing coronary heart disease. However, whether TFA intake is directly associated with the development of diabetes mellitus (DM) remains unknown.

Methods: We performed the 75-g oral glucose tolerance test in two Japanese cohorts: a cohort of 454 native Japanese living in Hiroshima, Japan, and a cohort of 426 Japanese-Americans living in Los Angeles, USA, who shared identical genetic predispositions but had different lifestyles. Serum elaidic acid concentration was measured and compared, and its association with insulin resistance was assessed.

Results: Serum elaidic acid concentrations were significantly higher in the Japanese-Americans (median, 18.2 µmol/L) than in the native Japanese (median, 11.0 µmol/L). The serum elaidic acid concentrations in the native Japanese DM group (16.0 µmol/L) were significantly higher compared with those in the normal glucose tolerance (10.8 µmol/L) and impaired glucose tolerance (11.7 µmol/L) groups. Multiple linear regression analyses showed that serum elaidic acid concentrations were significantly positively associated with homeostasis model assessment for insulin resistance (HOMA-IR) values after adjusting for various factors.

Conclusions: These results suggest that excessive TFA intake worsens insulin resistance and increases the risk of developing DM even in the native Japanese, whose intakes of animal fat and simple carbohydrates were presumed to be lower than those of the Japanese-Americans.

Immunohistochemistry of aldosterone synthase leads the way to the pathogenesis of primary aldosteronism

Our group previously purified human and rat aldosterone synthase (CYP11B2 and Cyp11b2, respectively) from their adrenals and verified that it is distinct from steroid 11β-hydroxylase (CYP11B1 or Cyp11b1), the cortisol- or corticosterone-synthesizing enzyme. We now describe their distributions immunohistochemically with specific antibodies. In rats, there is layered functional zonation with the Cyp11b2-positive zona glomerulosa (ZG), Cyp11b1-positive zona fasciculata (ZF), and Cyp11b2/Cyp11b1-negative undifferentiated zone between the ZG and ZF. In human infants and children (<12 years old), the functional zonation is similar to that in rats. In adults, the adrenal cortex remodels and subcapsular aldosterone-producing cell clusters (APCCs) replace the continuous ZG layer. We recently reported possible APCC-to-APA transitional lesions (pAATLs) in 2 cases of unilateral multiple adrenocortical micro-nodules. In this review, we present 4 additional cases of primary aldosteronism, from which the extracted adrenals contain pAATLs, with results of next generation sequencing for these lesions. Immunohistochemistry for CYP11B2 and CYP11B1 has become an important tool for the diagnosis of and research on adrenocortical pathological conditions and suggests that APCCs may be the origin of aldosterone-producing adenoma.

Hypomethylation of CYP11B2 in Aldosterone-Producing Adenoma

The purpose of this study was to evaluate the DNA methylation levels of steroidogenic enzyme genes in aldosterone-producing adenoma (APA) and the effects of gene mutations in APA on the DNA methylation levels. DNA methylation array analysis was conducted using nonfunctioning adrenocortical adenoma (n=12) and APA (n=35) samples, including some with a KCNJ5 mutation (n=21), an ATP1A1 mutation (n=5), and without the known mutations (n=9). The quantitative polymerase chain reaction assay was performed for the detection of CYP11B2 and CYP11B1 expression levels in nonfunctioning adrenocortical adenoma and APA. We introduced the KCNJ5 T158A mutation using lentivirus delivery in the human adrenocortical 15 cell line, and analyzed the effects of the mutation on DNA methylation levels. We analyzed the 83 presumed DNA methylation sites of steroidogenic enzymes. In APA, we found 7 hypomethylated sites in CYP11B2 and 1 hypomethylated and 6 hypermethylated sites in CYP11B1 There were no differences in the steroidogenic enzymes gene DNA methylation of peripheral leukocytes between nonfunctioning adrenocortical adenoma and APA. No CYP11B2 methylation level was associated with CYP11B2 transcription levels in APA. All methylation sites, except for a CYP11B2 region, showed no difference among APAs with or without gene mutations. Human adrenocortical 15 cells with the KCNJ5 mutation showed no changes in CYP11B2 or CYP11B1 methylation levels compared with control cells. We demonstrated that CYP11B2 in APA was extensively hypomethylated, and CYP11B2 methylation in the region with hypomethylation was not induced by KCNJ5 or ATP1A1 mutations that cause aldosterone overproduction in APA and a KCNJ5 mutation human adrenocortical 15 cells.

YPEL4 modulates HAC15 adrenal cell proliferation and is associated with tumor diameter

Yippee-like (YPEL) proteins are thought to be related to cell proliferation because of their structure and location in the cell. The aim of this study was to clarify the effects of YPEL4 on aldosterone production and cell proliferation in the human adrenocortical cell line (HAC15) and aldosterone producing adenoma (APA). Basal aldosterone levels in HAC15 cells over-expressing YPEL4 was higher than those of control HAC15 cells. The positive effects of YPEL4 on cell proliferation were detected by XTT assay and crystal violet staining. YPEL4 levels in 39 human APA were 2.4-fold higher compared to those in 12 non-functional adrenocortical adenomas, and there was a positive relationship between YPEL4 levels and APA diameter (r = 0.316, P < 0.05). In summary, we have demonstrated that YPEL4 stimulates human adrenal cortical cell proliferation, increasing aldosterone production as a consequence. These results in human adrenocortical cells are consistent with the clinical observations with APA in humans.

Gonadotropin-Releasing Hormone Stimulate Aldosterone Production in a Subset of Aldosterone-Producing Adenoma

We aimed to detect novel genes associated with G protein-coupled receptors (GPCRs) in aldosterone-producing adenoma (APA) and elucidate the mechanisms underlying aldosterone production.Microarray analysis targeting GPCR-associated genes was conducted using APA without known mutations (APA-WT) samples (n = 3) and APA with the KCNJ5 mutation (APA-KCNJ5; n = 3). Since gonadotropin-releasing hormone receptor (GNRHR) was the highest expression in APA-WT by microarray analysis, we investigated the effect of gonadotropin-releasing hormone (GnRH) stimulation on aldosterone production.The quantitative polymerase chain reaction assay results revealed higher GNRHR expression levels in APA-WT samples those in APA-KCNJ5 samples (P < 0.05). LHCGR levels were also significantly elevated in APA-WT samples, and there was a significant and positive correlation between GNRHR and LHCGR expression in all APA samples (r = 0.476, P < 0.05). Patients with APA-WT (n = 9), which showed higher GNRHR and LHCGR levels, had significantly higher GnRH-stimulated aldosterone response than those with APA-KCNJ5 (n = 13) (P < 0.05). Multiple regression analysis revealed that the presence of the KCNJ5 mutation was linked to GNRHR mRNA expression (β = 0.94 and P < 0.01). HAC15 cells with KCNJ5 gene carrying T158A mutation exhibited a significantly lower GNRHR expression than that in control cells (P < 0.05).We clarified increased expression of GNRHR and LHCGR in APA-WT, and the molecular analysis including the receptor expression associated with clinical findings of GnRH stimulation.