Analysis of unilateral adrenal hyperplasia with primary aldosteronism from the aspect of messenger ribonucleic acid expression for steroidogenic enzymes: a comparative study with adrenal cortices adhering to aldosterone-producing adenoma

Ectopic localization of CYP11B1 and CYP11B2-expressing cells in the normal human adrenal gland

The sharp line of demarcation between zona glomerulosa (ZG) and zona fasciculata (ZF) has been recently challenged suggesting that this interface is no longer a compartment boundary. We have used immunohistochemical analyses to study the steroid 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) pattern of expression and investigate the remodeling of the adrenal cortex in relation to aging. We analyzed human adrenal glands prepared from 47 kidney donors. No aldosterone-producing micronodules (APMs) were detectable in the younger donors aged between 22-39 but the functional ZG depicted by positive CYP11B2 staining demonstrated a lack of continuity. In contrast, the development of APMs was found in samples from individuals aged 40-70. Importantly, the progressive replacement of CYP11B2-expressing cells in the histological ZG by CYP11B1-expressing cells highlights the remodeling capacity of the adrenal cortex. In 70% of our samples, immunofluorescence studies revealed the presence of isolated or clusters of CYP11B2 positive cells in the ZF and zona reticularis. Our data emphasize that mineralocorticoid- and glucocorticoid-producing cells are distributed throughout the cortex and the medulla making the determination of the functional status of a cell or group of cells a unique tool in deciphering the changes occurring in adrenal gland particularly during aging. They also suggest that, in humans, steroidogenic cell phenotype defined by function is a stable feature and thus, the functional zonation might be not solely maintained by cell lineage conversion/migration.

Spontaneous Remission of Primary Aldosteronism with Mineralocorticoid Receptor Antagonist Therapy: A Review

In this review, we describe previous basic and clinical studies on autonomous aldosterone production. Over the past decades, mineralocorticoid receptor antagonists (MRAs) have been found to concentration-dependently inhibit steroidogenesis in different degrees. However, many studies have proven the suppressive effects of MRAs on the activities of hormone synthase. The probable factors of cytochrome P-450 reduction, both in microsomes and mitochondria, have also been considered: (1) one of the spironolactone metabolite forms had destructive function, except canrenone, (2) 7α-thio-spironolactone was an obligatory intermediate in the spironolactone-induced CYP450 decrease, and (3) the contributing steroids should have 7α-methylthio or 7α-methylsulfone groups. In previous clinical research, spironolactone-body-containing cells showed a type II pattern of enzyme activity (i.e., enhanced 3β-hydroxysteroid dehydrogenase, glucose-6-phosphate, and NADP-isocitrate dehydrogenase activities and weaken succinate dehydrogenase activity), and the subcapsular micronodules composed of spironolactone-body-containing cells also exhibited a type II pattern and excess aldosterone secretion, indicating that the subcapsular micronodules might be the root of aldosterone-producing adenoma. Moreover, combined with the potential impeditive function to aldosterone secretion, a few cases of spontaneous remission of primary aldosteronism, with normal ranges of blood pressure, plasma potassium, plasma renin activity, and aldosterone renin ratio, have been reported after long-term treatment with MRAs.

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.

The Potential Role of Aldosterone-Producing Cell Clusters in Adrenal Disease

Primary aldosteronism (PA) is the most common cause of secondary hypertension. The hallmark of PA is adrenal production of aldosterone under suppressed renin conditions. PA subtypes include adrenal unilateral and bilateral hyperaldosteronism. Considerable progress has been made in defining the role for somatic gene mutations in aldosterone-producing adenomas (APA) as the primary cause of unilateral PA. This includes the use of next-generation sequencing (NGS) to define recurrent somatic mutations in APA that disrupt calcium signaling, increase aldosterone synthase (CYP11B2) expression, and aldosterone production. The use of CYP11B2 immunohistochemistry on adrenal glands from normal subjects, patients with unilateral and bilateral PA has allowed the identification of CYP11B2-positive cell foci, termed aldosterone-producing cell clusters (APCC). APCC lie beneath the adrenal capsule and like APA, many APCC harbor somatic gene mutations known to increase aldosterone production. These findings suggest that APCC may play a role in pathologic progression of PA. Herein, we provide an update on recent research directed at characterizing APCC and also discuss the unanswered questions related to the role of APCC in PA.

Deoxycorticosterone-producing adenoma concomitant with aldosterone-producing microadenoma: a challenging combination

OBJECTIVE

To describe the challenging case of a 59-year-old male with a deoxycorticosterone (DOC)-producing adrenal adenoma concomitant with an aldosterone-producing microadenoma.

METHODS

We measured the patient's aldosterone and progesterone levels during adrenal venous sampling (AVS). The steroidogenic enzyme expression was studied with in situ hybridization (ISH). Steroids profiles were determined in the peripheral serum obtained before and after the operation, as well as in the main adrenal tumor.

RESULTS

The patient was diagnosed with primary aldosteronism (PA) based on typical clinical findings. He had an adrenal tumor located at the lower pole of the left adrenal gland. The aldosterone concentration in the adrenal vein proximal to the adrenal tumor was higher than that of the ipsilateral adrenal vein distal to the tumor during the AVS. Progesterone was only elevated in the adrenal vein proximal to the tumor, suggesting that the tumor produced steroids other than aldosterone. The postoperative findings revealed that the main tumor was accompanied by 2 microadenomas. The main adrenal tumor was diagnosed as a DOC-producing adenoma, and one of the microadenomas was diagnosed as aldosterone-producing based on the ISH and the determination of the steroid profiles.

CONCLUSIONS

Concomitant PA masked the key findings of a DOC-producing tumor; the suppression of aldosterone in this patient. Multiple sampling in the adrenal vein considering the location of the adrenal tumor provided a clue to the diagnosis. Progesterone measurement during AVS is easy and may be useful in diagnosing rare adrenal tumors that produce intermediate products in adrenal steroid biosynthesis.

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.

The Long-term Effect of Adrenal Arterial Embolization for Unilateral Primary Aldosteronism on Cardiorenovascular Protection, Blood Pressure, and the Endocrinological Profile

Primary aldosteronism (PA) is a major cause of secondary hypertension, divided into two subtypes: unilateral and bilateral. Unilateral PA (u-PA) is surgically-curable. Medical treatment with mineralocorticoid receptors antagonists is recommended as a second-line treatment when the patients are not candidate for surgical treatment. The present case was a 39-year-old woman with u-PA, who had refused surgery, had suffered from adverse effects of medical treatment. She was treated with transcatheter adrenal arterial embolization (TAAE). Her blood pressure had been well controlled without progression of cardiorenovascular damage for 12 years. TAAE can be the third treatment option for u-PA patients.

Clinical characteristics of primary hyperaldosteronism due to adrenal microadenoma

An increasing number of patients are being diagnosed with primary aldosteronism (PA) due to aldosterone-producing macroadenoma (APA). However, there are only limited data available on the clinical characteristics of PA that are associated with adrenal microadenoma. Of the 55 patients that were diagnosed with PA in our study, 22 patients showed a unilateral adrenal over-production of aldosterone. The histopathology of the surgically removed adrenal tissues led to six patients being diagnosed with microadenoma, and the clinical features of microadenoma, macroadenoma and idiopathic hyperaldosteronism (IHA) were studied. The expression levels of CYP11B2, CYP17, CYP21 and 3β-hydroxysteroid dehydrogenase 2 (HSD3B2) mRNA in the adrenal cortices (n=5 and 6, respectively) that remained attached to the adrenal microadenomas or macroadenomas were examined by real time-PCR and then compared to the expression levels in the adrenal cortices (n=5) of non-functioning adrenal adenomas (NF). The patients with microadenoma (n=6) had significantly higher diastolic blood pressure than the patients with macroadenoma (n=16) or IHA (n=33) (p<0.05). The systolic blood pressure, plasma aldosterone concentration, serum potassium level and renal function did not differ between the PA sub-groups. The levels of CYP11B2 and CYP17 mRNA were significantly increased in the adjacent tissues of microadenomas, as compared with macroadenomas or NF (p<0.05), whereas no significant differences in the CYP21 and HSD3B2 mRNA levels were found between the PA sub-groups. The tumor size did not influence the clinical characteristics of APA. The non-tumor portions of the microadenomas showed marked and sustained CYP11B2 mRNA expression under the suppressed renin-angiotensin system. We suggest that an increased number of microadenomas should be sampled, and the immunohistochemistry for steoridogenic enzymes should be investigated to clarify the etiology of microadenoma.

Primary aldosteronism, diagnosis and treatment in Japan

Primary aldosteronism (PA) has been recognized as a common cause of secondary hypertension and accounts for approximately 5-15% of the hypertensive population in Japan. Screening for PA should therefore be carried out in all hypertensive patients as we have shown the estimated prevalence of PA is 13.6% in pre-hypertensive subjects and 9.1% in stage 1 hypertensive patients. The screening test most advocated is the aldosterone-to-renin ratio (ARR), and when the ARR is >20 the following confirmatory tests should be carried out; the captopril challenge test, frusemide-upright test, or saline infusion test. Adrenal CT is not accurate for distinguishing between an aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). Adrenal venous sampling (AVS) is therefore essential for selecting the appropriate therapy in patients a high probability of PA who require surgical treatment. Rapid cortisol assays during AVS to monitor cortisol levels can reduce the failure associated with AVS. We have developed a new rapid cortisol assay using immunochromatography, in which cortisol concentration can be measured within 6 min. Using this technique, the success rate of AVS improved to 93%. IHA underlies about one-half of cases with PA; treatment with eplerenone (100 mg twice a daily), a specific mineralocorticoid receptor antagonist, results in substantial improvement in hypertension, with fewer side effects compared to spironolactone.

Progress in primary aldosteronism: present challenges and perspectives

Primary Aldosteronism (PA) is a disorder of the adrenal zona glomerulosa (ZG) in which aldosterone secretion is increased and is relatively autonomous of normal regulatory mechanisms. A recent conference in Munich organized by Prof. Reincke addressed advances and challenges related to the screening, diagnosis, and identification of uni- and bilateral involvement of the diseased adrenal of PA. Some infrequently addressed issues are described herein. We postulate that most cases of PA are due to the activation by unknown mechanisms of subset of cells resulting in the formation of a multiple foci or nodules of hyperactive zona glomerulosa cells. This implies that one or several yet unidentified stimuli can drive aldosterone overproduction, as well as the proliferation of aldosterone-producing cells. Current diagnostic procedures allow to determine whether inappropriate aldosterone production is driven by one or both adrenal glands and thus to establish optimal treatment.

Adrenocortical zonation in humans under normal and pathological conditions

CONTEXT

Aldosterone synthase (CYP11B2) and steroid 11 beta-hydroxylase (CYP11B1) catalyze the terminal steps for aldosterone and cortisol syntheses, respectively, thereby determining the functional differentiation of human adrenocortical cells. Little is known, however, about how the cells expressing the enzymes are actually distributed in the adrenals under normal and pathological conditions.

OBJECTIVE

The objective of the study was to determine the localization of CYP11B2 and -B1 in human adrenal specimens by using developed antibodies capable of distinguishing the two enzymes from each other.

RESULTS

Under normal conditions, CYP11B2 was sporadically detected in the zona glomerulosa, whereas CYP11B1 was entirely detected in the zonae fasciculata-reticularis. Adrenocortical cells lacking both enzymes were observed in the outer cortical regions. In addition to conventional zonation, we found a variegated zonation consisting of a subcapsular cell cluster expressing CYP11B2, which we termed aldosterone-producing cell cluster, and a CYP11B1-expressing area. Aldosterone-producing adenomas differed in cell populations expressing CYP11B2 from one another, whereas CYP11B1-expressing and double-negative cells were also intermingled. Adenomas from patients with Cushing's syndrome expressed CYP11B1 entirely but not CYP11B2, resulting in atrophic nontumor glands. The nontumor portions of both types of adenomas bore frequently one or more aldosterone-producing cell clusters, which sustained CYP11B2 expression markedly under the conditions of the suppressed renin-angiotensin system.

CONCLUSION

Immunohistochemistry of the human normal adrenal cortex for CYP11B2 and CYP11B1 revealed a variegated zonation with cell clusters constitutively expressing CYP11B2. This technique may provide a pathological confirmatory diagnosis of adrenocortical adenomas.

Bilateral aldosteronoma associated with secondary aldosteronism in a chronic hemodialysis subject

We demonstrated a rare case of bilateral aldosteronoma accompanied by secondary aldosteronism in a 37-year-old man with chronic renal failure on hemodialysis. He initially developed immunoglobulin A nephropathy at 11 years old, and had been treated with hemodialysis since the age of 17 years. His blood pressure was 110/68 mmHg, and no other abnormal findings were detected. Laboratory findings revealed that serum potassium was 3.9 mmol/L; plasma renin activity, 4.8 ng/ml/h and plasma aldosterone, 19,000 pg/mL. Abdominal computed tomography revealed bilateral adrenocortical tumors, measuring 34 and 40 mm in diameter in right and left tumors, respectively. (131)I-Adosterol scintigram showed bilateral accumulation. Left adrenalectomy was performed under laparoscopy. The tumor was encapsulated and well-circumscribed. The majority of the tumor was composed of a dark-brown portion admixed with sporadic foci of golden-yellow portions. Hyaline degeneration was detected in its central portion. The tumor was composed of clear cortical cells in viable portions. Tumor cells demonstrated immunoreactivity for the cholesterol side-chain cleavage enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD II) and 21-hydroxylase, but not 17 alpha-hydroxylase. In the adjacent non-neoplastic adrenals, 3 beta-HSD II was markedly present in the hyperplastic glomerulosa zone. These findings suggest that the presence of secondary aldosteronism, which is closely related to the conditions of chronic renal failure on hemodialysis, eventually promoted the development of bilateral aldosteronoma from the zona glomerulosa hyperplasia.

Cushing's syndrome by left adrenocortical adenoma synchronously associated with primary aldosteronism by right adrenocortical adenoma: report of a case

Synchronous associations of Cushing's syndrome (CS) and primary aldosteronism (PA) with multiple adrenocortical adenomas secreting each hormone independently have rarely been reported. Herein, we describe a unique case of PA associated with CS with detailed clinical and pathological investigations. Bilateral adrenal masses with clinical symptoms of CS and PA were found in a 43-year-old woman. Venous sampling demonstrated excess secretion of cortisol, and aldosterone from right, and left tumor, respectively. A bilateral laparoscopic partial adrenalectomy was undergone. The right adrenal tumor (3 cm) was yellow in color with abundant lipofuscin granules, and was composed of both eosinophilic compact cells and clear cells. In situ hybridization showed that both mRNAs for HSD3B2 and CYP17A1 were strongly expressed in the tumor, suggesting cortisol synthesis. Left adrenal tumor (2.4 cm) was golden-yellow in color, and composed of clear cells only. Expression of HSD3B2 and CYP11B mRNAs were observed in the tumor compatible with the aldosterone synthesis. Furthermore, minute nodules were found at the surface of normal-appearing cortex on both sides of the adrenal glands, and the expression of HSD3B2 and CYP11B mRNAs was clearly demonstrated within the nodules, indicating aldosterone synthesis. We diagnosed that the present case had 1) cortisol-producing right adrenocortical adenoma, 2) aldosterone producing left adrenocortical adenoma, and 3) cortical minute nodules with aldosterone production in both adrenal glands compatible with idiopathic adrenal hyperplasia. We reviewed the cases reported, and discussed the significance of the minute nodules in the adrenal cortex, often found in association with the adrenocortical adenoma.

Analysis of mRNA expression for steroidogenic enzymes in the remaining adrenal cortices attached to adrenocortical adenomas

DESIGN AND METHODS

We have recently demonstrated that the adrenal cortices attached to aldosterone-producing adenoma (APA) contained microscopic subcapsular micronodules suggestive of active aldosterone production. In this study, we used in situ hybridization to investigate the mRNA expression of steroidogenic enzymes in the adrenal cortices attached to cortisol-producing adenoma (CPA) and clinically silent adenoma (non-functioning adenoma; NFA), in addition to APA.

RESULTS

Microscopic subcapsular micronodules, which were several hundreds of micrometers in size and spheroid in shape, were observed in the cortices attached to CPA and NFA, as well as APA, at high frequency. Most of the cortical nodules in zona fasciculata to zona reticularis showed a suppressed steroidogenesis in the cortices attached to adenoma, but some expressed intensely all necessary steroidogenic enzyme mRNAs for cortisol synthesis.

CONCLUSIONS

It is thus necessary to keep in mind, on the occasion of subtotal adrenalectomy, that lesions with the potential to later develop into functional adrenocortical nodules may be present in other parts of the ipsilateral or contralateral adrenal cortices.

Ectopic adrenal tissue in the thorax: a case report with in situ hybridization and immunohistochemical studies

Ectopic or accessory adrenal tissues are usually found in the upper abdomen or along the path of descent of the gonads. The occurrence of supradiaphragmatic adrenal tissue is extremely rare. We report a case of ectopic adrenal tissue composed of both cortical and medullary cells in a 99-year-old woman. The lesion was found incidentally in the paratracheal region at autopsy. We performed in situ hybridization and immunohistochemistry to confirm that the ectopic adrenal tissue possessed the same steroidogenesis as a normal adrenal gland. The ectopic adrenal tissue was encapsulated by fibrous tissue and composed of cells expressing all steroidogenic enzyme mRNAs. The centrally located cells showed immunoreactivities for tyrosine hydroxylase (TH), dopamine beta hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT). Expression of ACTH receptor (ACTHR) was also evident. These findings indicated that this ectopic adrenal tissue had the capability for steroid and catecholamine biosynthesis under the control of ACTH, and that it might function adequately even under a condition of bilateral adrenal insufficiency.