Chronic activation of adrenal Gq signaling induces Cyp11b2 expression in the zona fasciculata and hyperaldosteronism

Hyperaldosteronism is often associated with inappropriate aldosterone production and aldosterone synthase (Cyp11b2) expression. Normally, Cyp11b2 expression is limited to the adrenal zona glomerulosa (ZG) and regulated by angiotensin II which signals through Gq protein-coupled receptors. As cells migrate inwards, they differentiate into 11β-hydroxylase-expressing zona fasciculata (ZF) cells lacking Cyp11b2. The mechanism causing ZG-specific aldosterone biosynthesis is still unclear. We investigated the effect of chronic Gq signaling using transgenic mice with a clozapine N-oxide (CNO)-activated human M3 muscarinic receptor (DREADD) coupled to Gq (hM3Dq) that was expressed throughout the adrenal cortex. CNO raised circulating aldosterone in the presence of a high sodium diet with greater response seen in females compared to males. Immunohistochemistry and transcriptomics indicated disrupted zonal Cyp11b2 expression while Wnt signaling remained unchanged. Chronic Gq-DREADD signaling also induced an intra-adrenal RAAS in CNO-treated mice. Chronic Gq signaling disrupted adrenal cortex zonal aldosterone production associated with ZF expression of Cyp11b2.

Elevated luteinizing hormone receptor signaling or selenium treatment leads to comparable changes in adrenal cortex histology and androgen-AR/ZIP9 signaling

The importance and regulation of adrenal androgen production and signaling are not completely understood and are scarcely studied. In addition, there is still a search for appropriate animal models and experimental systems for the investigation of adrenal physiology and disease. Therefore, the main objective of the study was to evaluate the effect of luteinizing hormone (LH) signaling and selenium (Se2+) exposure on androgen adrenal signaling via canonical androgen receptor (AR), and membrane androgen receptor acting as zinc transporter (zinc- and iron-like protein 9; ZIP9). For herein evaluations, adrenals isolated from transgenic mice with elevated LH receptor signaling (KiLHRD582G) and adrenals obtained from rabbits used for ex vivo adenal cortex culture and exposure to Se2+ were utilized. Tissues were assessed for morphological, morphometric, and Western blot analyses and testosterone and zinc level measurements.Comparison of adrenal cortex histology and morphometric analysis in KiLHRD582G mice and Se2+-treated rabbits revealed cell hypertrophy. No changes in the expression of proliferating cell nuclear antigen (PCNA) were found. In addition, AR expression was decreased (p < 0.001) in both KiLHRD582G mouse and Se2+-treated rabbit adrenal cortex while expression of ZIP9 showed diverse changes. Its expression was increased (P < 0.001) in KiLHRD582G mice and decreased (P < 0.001) in Se2+-treated rabbits but only at the dose 10 ug/100 mg/ tissue. Moreover, increased testosterone levels (P < 0.05) and zinc levels were detected in the adrenal cortex of KiLHRD582G mice whereas in rabbit adrenal cortex treated with Se2+, the effect was the opposite (P < 0.001).

Zona Glomerulosa-Derived Klotho Modulates Aldosterone Synthase Expression in Young Female Mice

Klotho plays a critical role in the regulation of ion and fluid homeostasis. A previous study reported that haplo-insufficiency of Klotho in mice results in increased aldosterone synthase (CYP11B2) expression, elevated plasma aldosterone, and high blood pressure. This phenotype was presumed to be the result of diminished Klotho expression in zona glomerulosa (zG) cells of the adrenal cortex; however, systemic effects on adrenal aldosterone production could not be ruled out. To examine whether Klotho expressed in the zG is indeed a critical regulator of aldosterone synthesis, we generated a tamoxifen-inducible, zG-specific mouse model of Klotho deficiency by crossing Klotho-flox mice with Cyp11b2-CreERT mice (zG-Kl-KO). Tamoxifen-treated Cyp11b2-CreERT animals (zG-Cre) served as controls. Rosa26-mTmG reporter mice were used for Cre-dependent lineage-marking. Two weeks after tamoxifen induction, the specificity of the zG-Cre line was verified using immunofluorescence analysis to show that GFP expression was restricted to the zG. RNA in situ hybridization revealed a 65% downregulation of Klotho messenger RNA expression in the zG of zG-Kl-KO female mice at age 12 weeks compared to control mice. Despite this significant decrease, zG-Kl-KO mice exhibited no difference in plasma aldosterone levels. However, adrenal CYP11B2 expression and the CYP11B2 promotor regulatory transcription factors, NGFIB and Nurr1, were enhanced. Together with in vitro experiments, these results suggest that zG-derived Klotho modulates Cyp11b2 but does not evoke a systemic phenotype in young adult mice on a normal diet. Further studies are required to investigate the role of adrenal Klotho on aldosterone synthesis in aged animals.

Aging effects in adrenal cortex of male Mongolian gerbil: A model for endocrine studies

The adrenal gland produces steroid hormones that act in the homeostasis of organisms. During aging, alterations in the hormonal balance affect the adrenal glands, but these have not yet been fully described due to the lack of adequate animal models. The adrenal gland of the Mongolian gerbil has a morphology similar to the primate's adrenal gland, which makes it a possible animal model for endocrine studies. Therefore, the current study aimed to study the morphophysiology of the adrenal gland under the effect of aging. For this purpose, males Meriones unguiculatus, aged three, six, nine, twelve, and fifteen months were used. Morphometric, immunohistochemical, and hormonal analyses were performed. It was observed that during aging the adrenal gland presents hypertrophy of the fasciculata and reticularis zones. Lipofuscin accumulation was observed during aging, in addition to changes in proliferation, cell death, and cell receptors. The analyses also showed that the gerbil presents steroidogenic enzymes and the production of steroid hormones, such as DHEA, like that found in humans. The data provide the first comprehensive assessment of the morphophysiology of the Mongolian gerbil adrenal cortex during aging, indicating that this species is a possible experimental model for studies of the adrenal gland and aging.

Suppressive action of nesfatin-1 and nesfatin-1-like peptide on cortisol synthesis in human adrenal cortex cells

Nucleobindin-derived peptides, nesfatin-1 [NESF-1] and nesfatin-1-like-peptide [NLP] have diverse roles in endocrine and metabolic regulation. While both peptides showed a stimulatory effect on the synthesis of proopiomelanocortin (POMC), the adrenocorticotropic hormone (ACTH) precursor in mouse corticotrophs, whether NESF-1 and NLP have any direct effect on glucocorticoid [GC] synthesis in the adrenal cortex remains unknown. The main aim of this study was to determine if NESF-1 and/or NLP act directly on adrenal cortex cells to regulate cortisol synthesis in vitro. Whether NLP injection affects stress-hormone gene expression in the adrenal gland and pituitary in vivo in mice was also assessed. In addition, cortisol synthetic pathway in Nucb1 knockout mice was studied. Human adrenal cortical [H295R] cells showed immunoreactivity for both NUCB1/NLP and NUCB2/NESF-1. NLP and NESF-1 decreased the abundance of steroidogenic enzyme mRNAs, and cortisol synthesis and release through the AC/PKA/CREB pathway in H295R cells. Similarly, intraperitoneal injection of NLP in mice decreased the expression of enzymes involved in glucocorticoid (GC) synthesis in the adrenal gland while increasing the expression of Pomc, Pcsk1 and Crhr1 in the pituitary. Moreover, the melanocortin 2 receptor (Mc2r) mRNA level was enhanced in the adrenal gland samples of NLP injected mice. However, the global genetic disruption in Nucb1 did not affect most steroidogenic enzyme mRNAs, and Pomc, Pcsk2 and Crhr1 mRNAs in mice adrenal gland and pituitary gland, respectively. Collectively, these data provide the first evidence for a direct inhibition of cortisol synthesis and secretion by NLP and NESF-1. NUCB peptides might still elicit a net stimulatory effect on GC synthesis and secretion through their positive effects on ACTH-MC2R pathway in the pituitary.

Mitochondrial morphology in the mouse adrenal cortex: Influence of chronic psychosocial stress

Mitochondria within the adrenal cortex play a key role in synthesizing steroid hormones. The adrenal cortex is organized in three functionally specialized zones (glomerulosa, fasciculata, and reticularis) that produce different classes of steroid hormones in response to various stimuli, including psychosocial stress. Given that the functions and morphology of mitochondria are dynamically related and respond to stress, we applied transmission electron microscopy (TEM) to examine potential differences in mitochondrial morphology under basal and chronic psychosocial stress conditions. We used the chronic subordinate colony housing (CSC) paradigm, a murine model of chronic psychosocial stress. Our findings quantitatively define how mitochondrial morphology differs among each of the three adrenal cortex zones under basal conditions, and show that chronic psychosocial stress mainly affected mitochondria in the zona glomerulosa, shifting their morphology towards the more typical glucocorticoid-producing zona fasciculata mitochondrial phenotype. Analysis of adrenocortical lipid droplets that provide cholesterol for steroidogenesis showed that chronic psychosocial stress altered lipid droplet diameter, without affecting droplet number or inter-organellar mitochondria-lipid droplet interactions. Together, our findings support the hypothesis that each adrenal cortex layer is characterized by morphologically distinct mitochondria and that this adrenal zone-specific mitochondrial morphology is sensitive to environmental stimuli, including chronic psychosocial stressors. Further research is needed to define the role of these stress-induced changes in mitochondrial morphology, particularly in the zona glomerulosa, on stress resilience and related behaviors.

Adrenal Abcg1 Controls Cholesterol Flux and Steroidogenesis

Cholesterol is the precursor of all steroids, but how cholesterol flux is controlled in steroidogenic tissues is poorly understood. The cholesterol exporter ABCG1 is an essential component of the reverse cholesterol pathway and its global inactivation results in neutral lipid redistribution to tissue macrophages. The function of ABCG1 in steroidogenic tissues, however, has not been explored. To model this, we inactivated Abcg1 in the mouse adrenal cortex, which led to an adrenal-specific increase in transcripts involved in cholesterol uptake and de novo synthesis. Abcg1 inactivation did not affect adrenal cholesterol content, zonation, or serum lipid profile. Instead, we observed a moderate increase in corticosterone production that was not recapitulated by the inactivation of the functionally similar cholesterol exporter Abca1. Altogether, our data imply that Abcg1 controls cholesterol uptake and biosynthesis and regulates glucocorticoid production in the adrenal cortex, introducing the possibility that ABCG1 variants may account for physiological or subclinical variation in stress response.

Endocrine Disruptors: Focus on the Adrenal Cortex

Endocrine-disrupting chemicals (EDCs) are exogenous substances known to interfere with endocrine homeostasis and promote adverse health outcomes. Their impact on the adrenal cortex, corticosteroids and their physiological role in the organism has not yet been sufficiently elucidated. In this review, we collect experimental and epidemiological evidence on adrenal disruption by relevant endocrine disruptors. In vitro data suggest significant alterations of gene expression, cell signalling, steroid production, steroid distribution, and action. Additionally, morphological studies revealed disturbances in tissue organization and development, local inflammation, and zone-specific hyperplasia. Finally, endocrine circuits, such as the hypothalamic-pituitary-adrenal axis, might be affected by EDCs. Many questions regarding the detection of steroidogenesis disruption and the effects of combined toxicity remain unanswered. Not only due to the diverse mode of action of adrenal steroids and their implication in many common diseases, there is no doubt that further research on endocrine disruption of the adrenocortical system is needed.

X-linked adrenoleukodystrophy and primary adrenal insufficiency

X-linked adrenoleukodystrophy (X-ALD; OMIM:300100) is a progressive neurodegenerative disorder caused by a congenital defect in the ATP-binding cassette transporters sub-family D member 1 gene (ABCD1) producing adrenoleukodystrophy protein (ALDP). According to population studies, X-ALD has an estimated birth prevalence of 1 in 17.000 subjects (considering both hemizygous males and heterozygous females), and there is no evidence that this prevalence varies among regions or ethnic groups. ALDP deficiency results in a defective peroxisomal β-oxidation of very long chain fatty acids (VLCFA). As a consequence of this metabolic abnormality, VLCFAs accumulate in nervous system (brain white matter and spinal cord), testis and adrenal cortex. All X-ALD affected patients carry a mutation on the ABCD1 gene. Nevertheless, patients with a defect on the ABCD1 gene can have a dramatic difference in the clinical presentation of the disease. In fact, X-ALD can vary from the most severe cerebral paediatric form (CerALD), to adult adrenomyeloneuropathy (AMN), Addison-only and asymptomatic forms. Primary adrenal insufficiency (PAI) is one of the main features of X-ALD, with a prevalence of 70% in ALD/AMN patients and 5% in female carriers. The pathogenesis of X-ALD related PAI is still unclear, even if a few published data suggests a defective adrenal response to ACTH, related to VLCFA accumulation with progressive disruption of adrenal cell membrane function and ACTH receptor activity. The reason why PAI develops only in a proportion of ALD/AMN patients remains incompletely understood. A growing consensus supports VLCFA assessment in all male children presenting with PAI, as early diagnosis and start of therapy may be essential for X-ALD patients. Children and adults with PAI require individualized glucocorticoid replacement therapy, while mineralocorticoid therapy is needed only in a few cases after consideration of hormonal and electrolytes status. Novel approaches, such as prolonged release glucocorticoids, offer potential benefit in optimizing hormonal replacement for X-ALD-related PAI. Although the association between PAI and X-ALD has been observed in clinical practice, the underlying mechanisms remain poorly understood. This paper aims to explore the multifaceted relationship between PAI and X-ALD, shedding light on shared pathophysiology, clinical manifestations, and potential therapeutic interventions.

Structure of rosettes in the zona glomerulosa of human adrenal cortex

Recent studies in mouse models have demonstrated that the multi-cellular rosette structure of the adrenal zona glomerulosa (ZG) is crucial for aldosterone production by ZG cells. However, the rosette structure of human ZG has remained unclear. The human adrenal cortex undergoes remodeling during aging, and one surprising change is the occurrence of aldosterone-producing cell clusters (APCCs). It is intriguing to know whether APCCs form a rosette structure like normal ZG cells. In this study, we investigated the rosette structure of ZG in human adrenal with and without APCCs, as well as the structure of APCCs. We found that glomeruli in human adrenal are enclosed by a laminin subunit β1 (lamb1)-rich basement membrane. In slices without APCCs, each glomerulus contains an average of 11 ± 1 cells. In slices with APCCs, each glomerulus in normal ZG contains around 10 ± 1 cells, while each glomerulus in APCCs has significantly more cells (average of 22 ± 1). Similar to what was observed in mice, cells in normal ZG or in APCCs of human adrenal formed rosettes through β-catenin- and F-actin-rich adherens junctions. The cells in APCCs form larger rosettes through enhanced adherens junctions. This study provides, for the first time, a detailed characterization of the rosette structure of human adrenal ZG and shows that APCCs are not an unstructured cluster of ZG cells. This suggests that the multi-cellular rosette structure may also be necessary for aldosterone production in APCCs.

Angiotensin II-dependent aldosterone production in the adrenal cortex

The adrenal cortex is responsible for production of adrenal steroid hormones and is anatomically divided into three distinct zones: zona glomerulosa secreting mineralocorticoids (mainly aldosterone), zona fasciculata secreting glucocorticoids (cortisol), and zona reticularis producing androgens. Importantly, due to their high lipophilicity, no adrenal steroid hormone (including aldosterone) is stored in vesicles but rather gets synthesized and secreted instantly upon cell stimulation with specific stimuli. Aldosterone is the most potent mineralocorticoid hormone produced from the adrenal cortex in response to either angiotensin II (AngII) or elevated K+ levels in the blood (hyperkalemia). AngII, being a peptide, cannot cross cell membranes and thus, uses two distinct G protein-coupled receptor (GPCR) types, AngII type 1 receptor (AT1R) and AT2R to exert its effects inside cells. In zona glomerulosa cells, AT1R activation by AngII results in aldosterone synthesis and secretion via two main pathways: (a) Gq/11 proteins that activate phospholipase C ultimately raising intracellular free calcium concentration; and (b) βarrestin1 and -2 (also known as Arrestin-2 and -3, respectively) that elicit sustained extracellular signal-regulated kinase (ERK) activation. Both pathways induce upregulation and acute activation of StAR (steroidogenic acute regulatory) protein, the enzyme that catalyzes the rate-limiting step in aldosterone biosynthesis. This chapter describes these two salient pathways underlying AT1R-induced aldosterone production in zona glomerulosa cells. We also highlight some pharmacologically important notions pertaining to the efficacy of the currently available AT1R antagonists, also known as angiotensin receptor blockers (ARBs) or sartans at suppressing both pathways, i.e., their inverse agonism efficacy at G proteins and βarrestins.

Functional interaction of Clock genes and bone morphogenetic proteins in the adrenal cortex

The bone morphogenetic protein (BMP) system in the adrenal cortex plays modulatory roles in the control of adrenocortical steroidogenesis. BMP-6 enhances aldosterone production by modulating angiotensin (Ang) II-mitogen-activated protein kinase (MAPK) signaling, whereas activin regulates the adrenocorticotropin (ACTH)-cAMP cascade in adrenocortical cells. A peripheral clock system in the adrenal cortex was discovered and it has been shown to have functional roles in the adjustment of adrenocortical steroidogenesis by interacting with the BMP system. It was found that follistatin, a binding protein of activin, increased Clock mRNA levels, indicating an endogenous function of activin in the regulation of Clock mRNA expression. Elucidation of the interrelationships among the circadian clock system, the BMP system and adrenocortical steroidogenesis regulated by the hypothalamic-pituitary-adrenal (HPA) axis would lead to an understanding of the pathophysiology of adrenal disorders and metabolic disorders and the establishment of better medical treatment from the viewpoint of pharmacokinetics.

Exposure to dipentyl phthalate in utero disrupts the adrenal cortex function of adult male rats by inhibiting SIRT1/PGC-1α and inducing AMPK phosphorylation

Di-n-pentyl phthalate (DPeP) is an endocrine-disrupting phthalate plasticizer. The objective of this study was to investigate the effect of DPeP on adrenocortical function in adult male rats following in utero exposure. DPeP (0, 10, 50, 100, and 500 mg/kg/day) was administered by gavage to pregnant Sprague-Dawley rats from gestational day 14 to 21. The morphology and function of the adrenal cortex in 56-day-old male offspring were studied. DPeP at 100 and 500 mg/kg/day significantly reduced serum aldosterone levels and at 500 mg/kg/day markedly reduced corticosterone and adrenocorticotropic hormone levels. DPeP at 10-500 mg/kg markedly reduced the thickness of zona glomerulosa without affecting the thickness of zona fasciculata. DPeP significantly downregulated the expression of Agtr1a, Mc2r, Scarb1, Cyp11a1, Hsd3b1, Cyp21, Cyp11b1, Cyp11b2, Nr5a1, Nr4a2, and Bcl2 genes as well as their proteins. DPeP at 500 mg/kg/day significantly increased phosphorylated AMPK, while DPeP at 100 mg/kg/day and higher doses reduced phosphorylated AKT1 and total SIRT1 level. DPeP at 100 and 500 μM markedly induced reactive oxygen species and apoptosis in H295R cells after 24 h of culture. In conclusion, in utero exposure to DPeP disrupts adrenocortical function of the adult male offspring by (1) increasing AMPK phosphorylation and decreasing AKT1 phosphorylation and SIRT1 levels, (2) reducing adrenocorticotropic hormone levels, and (3) possibly inducing oxidative stress and apoptosis.

Expression of the angiogenesis markers endocan in Cushing's syndrome due to cortisol producing adenoma

PURPOSE

In this study, we aimed to investigate the endocan expression in tissue samples of patients diagnosed with Cushing's syndrome (CS) due to Cortisol-Producing-Adenoma (CPA) and compare it with normal adrenal cortex tissue, and also to evaluate the correlations of endocan expression with clinical and histopathological features.

METHODS

11 patients who were operated for CS due to CPA between 2009-2021 and 14 control subjects with normal adrenal cortex were included in the study. Demographic, laboratory and clinicopathological data of the patients were recorded. Sections of 4-5 µm thickness were taken from paraffin blocks of patients diagnosed with CS due to CPA and control subjects with normal adrenal cortex tissue. The sections were then stained in a closed system automatic immunohistochemical staining device to perform immunohistochemical analysis. The endocan positive grade were determined based on the proportion of stained cells on a scale of negative to strong.

RESULTS

The number of subjects with positive endocan expression and the mean endocan expression level in the CS group were significantly higher than the control group (p = 0.005, p < 0.001, respectively). No correlation was found between endocan expression and clinical and histopathological features.

CONCLUSION

According to the results of our study, endocan overexpression in CPA tissues may be related to the hormonal functionality of CPA.

YM750, an ACAT Inhibitor, Acts on Adrenocortical Cells to Inhibit Aldosterone Secretion Due to Depolarization

Primary aldosteronism (PA) is considered the most common form of secondary hypertension, which is associated with excessive aldosterone secretion in the adrenal cortex. The cause of excessive aldosterone secretion is the induction of aldosterone synthase gene (CYP11B2) expression by depolarization of adrenocortical cells. In this study, we found that YM750, an Acyl-coenzyme A: cholesterol acyltransferase (ACAT) inhibitor, acts on adrenocortical cells to suppress CYP11B2 gene expression and aldosterone secretion. YM750 inhibited the induction of CYP11B2 gene expression by KCl stimulation, but not by angiotensin II and forskolin stimulation. Interestingly, YM750 did not inhibit KCl-stimulated depolarization via an increase in intracellular calcium ion concentration. Moreover, ACAT1 expression was relatively abundant in the zona glomerulosa (ZG) including these CYP11B2-positive cells. Thus, YM750 suppresses CYP11B2 gene expression by suppressing intracellular signaling activated by depolarization. In addition, ACAT1 was suggested to play an important role in steroidogenesis in the ZG. YM750 suppresses CYP11B2 gene expression and aldosterone secretion in the adrenal cortex, suggesting that it may be a potential therapeutic agent for PA.

Sex differences in adrenal cortex beta-catenin immunolocalisation of the Saharan gerbil, Libyan jird (Meriones libycus, Lichtenstein, 1823)

BACKGROUND

The adrenal cortex provides adequate steroidogenic responses to environmental changes. However, in desert rodents, the adrenocortical activity varies according to several factors especially sex, age, and seasonal variations. Herein, we examined the sex differences in the adrenal cortex activity and explored the involvement of sex hormones in the regulation of this function in Libyan jird Meriones libycus.

MATERIALS AND METHODS

Twenty-four adult male and female animals weighing 109-110 g were captured in the breeding season and equally assigned into control and gonadectomised groups. Animal euthanasia was performed 50 days after the gonadectomy. Adrenal gland was processed for structural and immunohistochemistry study of b-catenin, whereas plasma was used for cortisol assay.

RESULTS

The results showed that female adrenal gland weight was heavier than male and gonadectomy reduced this dimorphism. The adrenal cortex thickness was greater in the female than in the male, mainly due to significant development of the zona fasciculata. Females presented higher cell density in fasciculata and reticularis zones. The plasma cortisol was higher in females than in males. The immunolocalisation of beta-catenin showed that the expression was particularly glomerular in both sexes. However, in the female, the immunostaining was present in the zona reticularis while it was absent in the control male. Orchiectomy reduced zona glomerulosa cell density and induced hypertrophy of zona reticularis characterised by strong beta-catenin immunoreactivity.

CONCLUSIONS

Results indicated that sex hormones had a major role in the regulation of the Saharan gerbil's adrenal homeostasis by modulating beta-catenin signalling. Androgens seem to inhibit the Wnt-beta-catenin pathway and oestrogens are activators of the adrenal inner zones.

A Comprehensive Investigation of Steroidogenic Signaling in Classical and New Experimental Cell Models of Adrenocortical Carcinoma

Adrenocortical carcinoma is a heterogeneous and aggressive cancer that originates from steroidogenic cells within the adrenal cortex. In this study, we have assessed for the preclinical gold standard NCI-H295 in direct comparison with the more recently established MUC-1 and a here newly reported ACC cell line (TVBF-7) the mutational status of important driver genes (TP53, MEN1, PRKAR1A, CTNNB1, APC, ZNRF-3, IGF-2, EGFR, RB1, BRCA1, BRCA2, RET, GNAS and PTEN), Wnt-signaling specificities (CTNNB1 mutation vs. APC mutation vs. wildtype), steroidogenic-(CYP11A1, CYP17A1, HSD3B2, HSD17B4, CYP21A2, CYP11B1, CYP11B2, MC2R, AT1R) and nuclear-receptor-signaling (AR, ER, GCR), varying electrophysiological potentials as well as highly individual hormone secretion profiles (Cortisol, Aldosterone, DHEA, DHEAS, Testosterone, 17-OH Progesterone, among others) which were investigated under basal and stimulated conditions (ACTH, AngII, FSK). Our findings reveal important genetic and pathophysiological characteristics for these three cell lines and reveal the importance of such cell-line panels reflecting differential endocrine functionalities to thereby better reflect clinically well-known ACC patient heterogeneities in preclinical studies.

Colocalization of Wnt/β-Catenin and ACTH Signaling Pathways and Paracrine Regulation in Aldosterone-producing Adenoma

CONTEXT

Aldosterone-producing adenomas (APAs) are a common cause of primary aldosteronism (PA). Despite the discovery of somatic mutations in APA and the characterization of multiple factors regulating adrenal differentiation and function, the sequence of events leading to APA formation remains to be determined.

OBJECTIVE

We investigated the role of Wnt/β-catenin and adrenocorticotropin signaling, as well as elements of paracrine regulation of aldosterone biosynthesis in adrenals with APA and their relationship to intratumoral heterogeneity and mutational status.

METHODS

We analyzed the expression of aldosterone-synthase (CYP11B2), CYP17A1, β-catenin, melanocortin type 2 receptor (MC2R), phosphorlyated cAMP response element-binding protein (pCREB), tryptase, S100, CD34 by multiplex immunofluorescence, and immunohistochemistry-guided reverse transcription-quantitative polymerase chain reaction. Eleven adrenals with APA and 1 with micronodular hyperplasia from patients with PA were analyzed. Main outcome measures included localization of CYP11B2, CYP17A1, β-catenin, MC2R, pCREB, tryptase, S100, CD34 in APA and aldosterone-producing cell clusters (APCCs).

RESULTS

Immunofluorescence revealed abundant mast cells and a dense vascular network in APA, independent of mutational status. Within APA, mast cells were localized in areas expressing CYP11B2 and were rarely colocalized with nerve fibers, suggesting that their degranulation is not controlled by innervation. In these same areas, ß-catenin was activated, suggesting a zona glomerulosa cell identity. In heterogeneous APA with KCNJ5 mutations, MC2R and vascular endothelial growth factor A expression was higher in areas expressing CYP11B2. A similar pattern was observed in APCC, with high expression of CYP11B2, activated β-catenin, and numerous mast cells.

CONCLUSION

Our results suggest that aldosterone-producing structures in adrenals with APA share common molecular characteristics and cellular environment, despite different mutation status, suggesting common developmental mechanisms.

The Immunoregulatory Actions of DHEA in Tuberculosis, A Tool for Therapeutic Intervention?

Dehydroepiandrosterone (DHEA) is an androgen synthesized by the adrenal cortex, which is an intermediary in the biosynthesis of sex hormones, such as testosterone and estradiol. DHEA mostly circulates as a conjugated ester, in the form of sulfate (DHEA-S). There exist several endogenous factors able to influence its synthesis, the most common ones being the corticotrophin-releasing hormone (CRH), adrenocorticotrophin (ACTH), growth factors, and proinflammatory cytokines, among others. Like other steroid hormones, DHEA, can alter the functioning of immune cells and therefore the course of diseases exhibiting an immune-inflammatory component, mostly from autoimmune or infectious nature. We herein review the role played by DHEA during a major infectious disease like tuberculosis (TB). Data recorded from TB patients, mouse models, or in vitro studies show that DHEA is likely to be implied in better disease control. This provides a stimulating background for carrying out clinical studies aimed at assessing the usefulness of DHEA as an adjuvant in TB patients.

Adrenal hyperplasias in childhood: An update

Pediatric adrenocortical hyperplasias are rare; they usually present with Cushing syndrome (CS); of them, isolated micronodular adrenal disease and its variant, primary pigmented adrenocortical disease are the most commonly encountered. Most cases are due to defects in the cyclic AMP/protein kinase A (cAMP/PKA) pathway, although a few cases remain without an identified genetic defect. Another cause of adrenal hyperplasia in childhood is congenital adrenal hyperplasia, a group of autosomal recessive disorders that affect steroidogenic enzymes in the adrenal cortex. Clinical presentation varies and depends on the extent of the underlying enzymatic defect. The most common form is due to 21-hydroxylase deficiency; it accounts for more than 90% of the cases. In this article, we discuss the genetic etiology of adrenal hyperplasias in childhood.

Inhibition of endogenous ouabain by atrial natriuretic peptide is a guanylyl cyclase independent effect

Background

Endogenous ouabain (EO) and atrial natriuretic peptide (ANP) are important in regulation of sodium and fluid balance. There is indirect evidence that ANP may be involved in the regulation of endogenous cardenolides.

Methods

H295R are human adrenocortical cells known to release EO. Cells were treated with ANP at physiologic concentrations or vehicle (0.1% DMSO), with or without guanylyl cyclase inhibitor 1,2,4 oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Cyclic guanosine monophosphate (cGMP), the intracellular second messenger of ANP, was measured by a chemiluminescent immunoassay and EO was measured by radioimmunoassay of C18 extracted samples.

Results

EO secretion is inhibited by ANP treatment, with the most prolonged inhibition (90 min vs ≤ 60 min) occurring at physiologic ANP concentrations (50 pg/mL). Inhibition of guanylyl cyclase with ODQ, also reduces EO secretion. The inhibitory effects on EO release in response to cotreatment with ANP and ODQ appeared to be additive.

Conclusions

ANP inhibits basal EO secretion, and it is unlikely that this is mediated through ANP-A or ANP-B receptors (the most common natriuretic peptide receptors) or their cGMP second messenger; the underlying mechanisms involved are not revealed in the current studies. The role of ANP in the control of EO synthesis and secretion in vivo requires further investigation.

Adrenal Corticosteroid Perturbation by the Endocrine Disruptor BDE-47 in a Human Adrenocortical Cell Line and Male Rats

Polybrominated diphenyl ethers (PBDEs) have been previously shown to alter various endocrine biosynthetic pathways. Growing epidemiological evidence suggests that PBDEs alter cardiovascular function. The goal of this study was to examine the effects of BDE-47 on adrenal corticosteroid pathways that play vital roles in cardiovascular homeostasis and pathophysiology. The effect of BDE-47 on aldosterone and cortisol secretion was characterized in a human adrenocortical cell line. HAC15 cells were exposed to various concentrations of BDE-47 (1 nM to 100 μM). Cell viability, corticosteroid secretion, gene expression of enzymes involved in corticosteroid synthesis, and metabolic activity was examined. Additionally, Sprague Dawley male rats were orally exposed to BDE-47 (10 or 100 µg/kg), 5 days per week for 16 weeks. Organ weights and plasma corticosteroid levels were measured. In HAC15 cells, basal and stimulated aldosterone and cortisol secretion was significantly increased by BDE-47. Gene expression of several enzymes involved in corticosteroid synthesis and mitochondrial metabolism also increased. In Sprague Dawley rats, adrenal but not heart, kidney, or liver weights, were significantly increased in BDE-47 treatment groups. Plasma corticosterone levels were significantly increased in the 100 µg BDE-47/kg treatment group. No change in plasma aldosterone levels were observed with BDE-47 exposure. These data indicate that BDE-47 disrupts the regulation of corticosteroid secretion and provides further evidence that PBDEs are potential endocrine disruptors. Future studies will determine the underlying molecular mechanism of altered corticosteroid production and examine whether these alterations result in underlying cardiovascular disease in our rodent model of 16-week BDE-47 exposure.

Evidence for local aldosterone synthesis in the large intestine of the mouse

Aldosterone, the main physiological mineralocorticoid, regulates sodium and potassium balance in the distal convoluted tubule of the kidney. Aldosterone is synthesized from cholesterol in the adrenal cortex in a sequence of enzymatic steps. Recently however, several tissues or cells e.g. brain, heart, blood vessels, kidneys and adipocytes have been shown to possess capability to produce aldosterone locally, and there is some evidence that this occurs also in the intestine. Colon expresses mineralocorticoid receptors and is capable of synthesizing corticosterone, the second last intermediate on the route to aldosterone from cholesterol. Based on such reports and on our preliminary finding, we hypothesized that aldosterone could be synthesized locally in the intestine and therefore we measured the concentration of aldosterone as well as the protein and gene expression of aldosterone synthase (CYP11B2), an enzyme responsible on aldosterone synthesis, from the distal section of the gastrointestinal tract of 10-week-old Balb/c male mice. It is known that sodium deficiency regulates aldosterone synthesis in adrenal glands, therefore we fed the mice with low (0.01%), normal (0.2%) and high-sodium (1.6%) diets for 14 days. Here we report that, aldosterone was detected in colon and cecum samples. Measurable amounts of CYP11B2 protein were detected by Western blot and Elisa analysis from both intestinal tissues. We detected CYP11B2 gene expression from the large intestine along with immunohistochemical findings of CYP11B2 in colonic wall. Sodium depletion increased the aldosterone concentration in plasma compared to control and high-sodium groups as well as in the intestine compared to mice fed with the high-sodium diet. To summarize, this study further supports the presence of aldosterone and the enzyme needed to produce this mineralocorticoid in the murine large intestine.

Steroidogenic cell microenvironment and adrenal function in physiological and pathophysiological conditions

The human adrenal cortex is a complex organ which is composed of various cell types including not only steroidogenic cells but also mesenchymal cells, immunocompetent cells and neurons. Intermingling of these diverse cell populations favors cell-to-cell communication processes involving local release of numerous bioactive signals such as biogenic amines, cytokines and neuropeptides. The resulting paracrine interactions play an important role in the regulation of adrenocortical cell functions both in physiological and pathophysiological conditions. Especially, recent evidence indicates that adrenocortical cell microenvironment is involved in the pathogenesis of adrenal disorders associated with corticosteroid excess. The paracrine factors involved in these intraadrenal regulatory mechanisms may thus represent valuable targets for future pharmacological treatments of adrenal diseases.

Targeted RNA sequencing of adrenal zones using immunohistochemistry-guided capture of formalin-fixed paraffin-embedded tissue

Adequate access to fresh or frozen normal adrenal tissue has been a primary limitation to the enhanced characterization of the adrenal zones via RNA sequencing (RNAseq). Herein, we describe the application of targeted RNAseq to formalin-fixed paraffin-embedded (FFPE) normal adrenal gland specimens. Immunohistochemistry (IHC) was used to visualize and guide the capture of the adrenocortical zones and medulla. Following IHC-based tissue capture and isolation of RNA, high-throughput targeted RNAseq highlighted clear transcriptomic differences and identified differentially expressed genes among the adrenal zones. Our data demonstrate the ability to capture FFPE adrenal zone tissue for targeted transcriptomic analyses. Future comparison of normal adrenal zones will improve our understanding of transcriptomic patterns and help identify potential novel pathways controlling zone-specific steroid production.

Adrenal medulla development and medullary-cortical interactions

The mammalian adrenal gland is composed of two distinct tissue types in a bidirectional connection, the catecholamine-producing medulla derived from the neural crest and the mesoderm-derived cortex producing steroids. The medulla mainly consists of chromaffin cells derived from multipotent nerve-associated descendants of Schwann cell precursors. Already during adrenal organogenesis, close interactions between cortex and medulla are necessary for proper differentiation and morphogenesis of the gland. Moreover, communication between the cortex and the medulla ensures a regular function of the adult adrenal. In tumor development, interfaces between the two parts are also common. Here, we summarize the development of the mammalian adrenal medulla and the current understanding of the cortical-medullary interactions under development and in health and disease.

Comparative proteomic analysis to identify the novel target gene of angiotensin II in adrenocortical H295R cells

Angiotensin II (Ang II) is a well-known peptide that maintains the balance of electrolytes in the higher vertebrates. Ang II stimulation in the adrenal gland induces the synthesis of mineralocorticoids, mainly aldosterone, through the up-regulation of aldosterone synthase (CYP11B2) gene expression. Additionally, it has been reported that Ang II activates multiple signaling pathways such as mitogen-activated protein kinase (MAPK) and Ca²⁺ signaling. Although Ang II has various effects on the cellular signaling in the adrenal cells, its biological significance, except for the aldosterone synthesis, is still unclear. In this study, we attempted to search the novel target gene(s) of Ang II in the human adrenal H295R cells using a proteomic approach combined with stable isotopic labeling using amino acid in cell culture (SILAC). Interestingly, we found that Ang II stimulation elevated the expression of phosphofructokinase type platelet (PFKP) in both protein and mRNA levels. Moreover, transactivation of PFKP by Ang II was dependent on extracellular-signal-regulated kinase (ERK) 1/2 activation. Finally, we observed that Ang II treatment facilitated glucose uptake in the H295R cells. Taken together, we here identified PFKP as a novel target gene of Ang II, indicating that Ang II not only stimulates steroidogenesis but also affects glucose metabolism.

The Age-Dependent Changes of the Human Adrenal Cortical Zones Are Not Congruent

BACKGROUND

While previous studies indicate that the zonae reticularis (ZR) and glomerulosa (ZG) diminish with aging, little is known about age-related transformations of the zona fasciculata (ZF).

OBJECTIVES

To investigate the morphological and functional changes of the adrenal cortex across adulthood, with emphasis on (i) the understudied ZF and (ii) sexual dimorphisms.

METHODS

We used immunohistochemistry to evaluate the expression of aldosterone synthase (CYP11B2), visinin-like protein 1 (VSNL1), 3β-hydroxysteroid dehydrogenase type II (HSD3B2), 11β-hydroxylase (CYP11B1), and cytochrome b5 type A (CYB5A) in adrenal glands from 60 adults (30 men), aged 18 to 86. Additionally, we employed mass spectrometry to quantify the morning serum concentrations of cortisol, 11-deoxycortisol (11dF), 17α-hydroxyprogesterone, 11-deoxycorticosterone, corticosterone, and androstenedione in 149 pairs of age- and body mass index-matched men and women, age 21 to 95 years.

RESULTS

The total cortical area was positively correlated with age (r = 0.34, P = 0.008). Both the total (VSNL1-positive) and functional ZG (CYP11B2-positive) areas declined with aging in men (r = -0.57 and -0.67, P < 0.01), but not in women. The CYB5A-positive area declined with age in both sexes (r = -0.76, P < 0.0001). In contrast, the estimated ZF area correlated positively with age in men (r = 0.59, P = 0.0006) and women (r = 0.49, P = 0.007), while CYP11B1-positive area remained unchanged across ages. Serum cortisol, corticosterone, and 11-deoxycorticosterone levels were stable across ages, while 11dF levels increased slightly with age (r = 0.16, P = 0.007).

CONCLUSION

Unlike the ZG and ZR, the ZF and the total adrenal cortex areas enlarge with aging. An abrupt decline of the ZG occurs with age in men only, possibly contributing to sexual dimorphism in cardiovascular risk.

Involvement of clock gene expression, bone morphogenetic protein and activin in adrenocortical steroidogenesis by human H295R cells

Functional interactions between the levels of clock gene expression and adrenal steroidogenesis were studied in human adrenocortical H295R cells. Fluctuations of Bmal1, Clock, Per2 and Cry1 mRNA levels were found in H295R cells treated with forskolin (FSK) in a serum-free condition. The changes of clock gene expression levels were diverged, with Clock mRNA level being significantly higher than Cry1 and Per2 mRNA levels after 12-h stimulation with FSK. After FSK induction, mRNA levels of StAR and CYP11B2 were highest at 12 hours and CYP17 mRNA level reached a peak at 6 hours, but HSD3B1 mRNA level was transiently decreased at 3 hours. The expression levels of Clock mRNA showed a significant positive correlation with StAR among the interrelationships between mRNA levels of key steroidogenic factors and clock genes. Knockdown of Clock gene by siRNA led to a significant reduction of FSK-induced expression of StAR and CYP17 after 12-h treatment with FSK. BMP-6 and activin, which modulate adrenal steroidogenesis, had inhibitory effects on Clock mRNA expression, whereas treatment with follistatin, a binding protein of activin, increased Clock mRNA levels in the presence of FSK, suggesting an endogenous function of activin in regulation of Clock mRNA expression. Collectively, the results indicated that changes of Clock mRNA expression, being upregulated by FSK and suppressed by BMP-6 and activin, were tightly linked to StAR expression by human adrenocortical cells.

β-catenin in adrenal zonation and disease

The Wnt signaling pathway is a critical mediator of the development and maintenance of several tissues. The adrenal cortex is highly dependent upon Wnt/β-catenin signaling for proper zonation and endocrine function. Adrenocortical cells emerge in the peripheral capsule and subcapsular cortex of the gland as progenitor cells that centripetally differentiate into steroid hormone-producing cells of three functionally distinct concentric zones that respond robustly to various endocrine stimuli. Wnt/β-catenin signaling mediates adrenocortical progenitor cell fate and tissue renewal to maintain the gland throughout life. Aberrant Wnt/β-catenin signaling contributes to various adrenal disorders of steroid production and growth that range from hypofunction and hypoplasia to hyperfunction, hyperplasia, benign adrenocortical adenomas, and malignant adrenocortical carcinomas. Great strides have been made in defining the molecular underpinnings of adrenocortical homeostasis and disease, including the interplay between the capsule and cortex, critical components involved in maintaining the adrenocortical Wnt/β-catenin signaling gradient, and new targets in adrenal cancer. This review seeks to examine these and other recent advancements in understanding adrenocortical Wnt/β-catenin signaling and how this knowledge can inform therapeutic options for adrenal disease.

Androgen Receptor Is Dispensable for X-Zone Regression in the Female Adrenal but Regulates Post-Partum Corticosterone Levels and Protects Cortex Integrity

Adrenal androgens are fundamental mediators of ovarian folliculogenesis, embryonic implantation, and breast development. Although adrenal androgen function in target tissues are well characterized, there is little research covering the role of androgen-signaling within the adrenal itself. Adrenal glands express AR which is essential for the regression of the X-zone in male mice. Female mice also undergo X-zone regression during their first pregnancy, however whether this is also controlled by AR signaling is unknown. To understand the role of the androgen receptor (AR) in the female adrenal, we utilized a Cyp11a1-Cre to specifically ablate AR from the mouse adrenal cortex. Results show that AR-signaling is dispensable for adrenal gland development in females, and for X-zone regression during pregnancy, but is required to suppress elevation of corticosterone levels post-partum. Additionally, following disruption to adrenal AR, aberrant spindle cell development is observed in young adult females. These results demonstrate sexually dimorphic regulation of the adrenal X-zone by AR and point to dysfunctional adrenal androgen signaling as a possible mechanism in the early development of adrenal spindle cell hyperplasia.

The establishment of a novel high-throughput screening system using RNA-guided genome editing to identify chemicals that suppress aldosterone synthase expression

Aldosterone is synthesized in the adrenal by the aldosterone synthase CYP11B2. Although the control of CYP11B2 expression is important to maintain the mineral homeostasis, its overexpression induced by the depolarization-induced calcium (Ca2+) signaling activation has been reported to increase the synthesis of aldosterone in primary aldosteronism (PA). The drug against PA focused on the suppression of CYP11B2 expression has not yet been developed, since the molecular mechanism of CYP11B2 transcriptional regulation activated via Ca2+ signaling remains unclear. To address the issue, we attempted to reveal the mechanism of the transcriptional regulation of CYP11B2 using chemical screening. We generated a cell line by inserting Nanoluc gene as a reporter into CYP11B2 locus in H295R adrenocortical cells using the CRSPR/Cas9 system, and established the high-throughput screening system using the cell line. We then identified 9 compounds that inhibited the CYP11B2 expression induced by potassium-mediated depolarization from the validated compound library (3399 compounds). Particularly, tacrolimus, an inhibitor of phosphatase calcineurin, strongly suppressed the CYP11B2 expression even at 10 nM. These results suggest that the system is effective in identifying drugs that suppress the depolarization-induced CYP11B2 expression. Our screening system may therefore be a useful tool for the development of novel medicines against PA.

Embryonic Development and Adult Regeneration of the Adrenal Gland

The adrenal gland plays a pivotal role in an organism's health span by controlling the endocrine system. Decades of research on the adrenal gland have provided multiscale insights into the development and maintenance of this essential organ. A particularly interesting finding is that founder stem/progenitor cells participate in adrenocortical development and enable the adult adrenal cortex to regenerate itself in response to hormonal stress and injury. Since major advances have been made in understanding the dynamics of the developmental process and the remarkable regenerative capacity of the adrenal gland, understanding the mechanisms underlying adrenal development, maintenance, and regeneration will be of interest to basic and clinical researchers. Here, we introduce the developmental processes of the adrenal gland and discuss current knowledge regarding stem/progenitor cells that regulate adrenal cortex remodeling and regeneration. This review will provide insights into the fascinating ongoing research on the development and regeneration of the adrenal cortex.

Functional imaging with 11C-metomidate PET for subtype diagnosis in primary aldosteronism

OBJECTIVE

Endocrine Society guidelines recommend adrenal venous sampling (AVS) in primary aldosteronism (PA) if adrenalectomy is considered. We tested whether functional imaging of adrenal cortex with 11C-metomidate (11C-MTO) could offer a noninvasive alternative to AVS in the subtype classification of PA.

DESIGN

We prospectively recruited 58 patients with confirmed PA who were eligible for adrenal surgery.

METHODS

Subjects underwent AVS and 11C-MTO-PET without dexamethasone pretreatment in random order. The lateralization of 11C-MTO-PET and adrenal CT were compared with AVS in all subjects and in a prespecified adrenalectomy subgroup in which the diagnosis was confirmed with immunohistochemical staining for CYP11B2.

RESULTS

In the whole study population, the concordance of AVS and 11C-MTO-PET was 51% and did not differ from that of AVS and adrenal CT (53%). The concordance of AVS and 11C-MTO-PET was 55% in unilateral and 44% in bilateral PA. In receiver operating characteristics analysis, the maximum standardized uptake value ratio of 1.16 in 11C-MTO-PET had an AUC of 0.507 (P = n.s.) to predict allocation to adrenalectomy or medical therapy with sensitivity of 55% and specificity of 44%. In the prespecified adrenalectomy subgroup, AVS and 11C-MTO-PET were concordant in 10 of 19 subjects with CYP11B2-positive adenoma and in 6 of 10 with CYP11B2-positivity without an adenoma.

CONCLUSIONS

The concordance of 11C-MTO-PET with AVS was clinically suboptimal, and did not outperform adrenal CT. In a subgroup with CYP11B2-positive adenoma, 11C-MTO-PET identified 53% of cases. 11C-MTO-PET appeared to be inferior to AVS for subtype classification of PA.

Adropin Stimulates Proliferation and Inhibits Adrenocortical Steroidogenesis in the Human Adrenal Carcinoma (HAC15) Cell Line

Adropin is a multifunctional peptide hormone encoded by the ENHO (energy homeostasis associated) gene. It plays a role in mechanisms related to increased adiposity, insulin resistance, as well as glucose, and lipid metabolism. The low adropin levels are strongly associated with obesity independent insulin resistance. On the other hand, overexpression or exogenous administration of adropin improves glucose homeostasis. The multidirectional, adropin-related effects associated with the regulation of metabolism in humans also appear to be attributable to the effects of this peptide on the activity of various elements of the endocrine system including adrenal cortex. Therefore, the main purpose of the present study was to investigate the effect of adropin on proliferation and secretory activity in the human HAC15 adrenal carcinoma cell line. In this study, we obtained several highly interesting findings. First, GPR19, the main candidate sensitizer of adrenocortical cells to adropin, was expressed in HAC15 cells. Moreover, GPR19 expression was relatively stable and not regulated by ACTH, forskolin, or adropin itself. Our findings also suggest that adropin has the capacity to decrease expression levels of steroidogenic genes such as steroidogenic acute regulatory protein (StAR) and CYP11A1, which then led to a statistically significant inhibition in cortisol and aldosterone biosynthesis and secretion. Based on whole transcriptome study and research involving transforming growth factor (TGF)-β type I receptor kinase inhibitor we demonstrated that attenuation of steroidogenesis caused by adropin is mediated by the TGF-β signaling pathway likely to act through transactivation mechanism. We found that HAC15 cells treated with adropin presented significantly higher proliferation levels than untreated cells. Using specific intracellular inhibitors, we showed that adropin stimulate proliferation via ERK1/2 and AKT dependent signaling pathways. We have also demonstrated that expression of GPR19 is elevated in adrenocortical carcinoma in relation to normal adrenal glands. High level of GPR19 expression in adrenocortical carcinoma may constitute a negative prognostic factor of disease progression.

Positive Immunostaining for Succinate Dehydrogenase B (SDHB) in Paraganglioma Associated with Germline Mutation of SDHB, L157X and P236S

PURPOSE

Pheochromocytoma (PCC) and paraganglioma (PGL) associated with the succinate dehydrogenase (SDH) germline mutations are characterized by negative results of immunohistochemistry tests for SDH subunit B (SDHB). Genetic testing for the SDH complex (SDHA, SDHB, SDHC, SDHD, and SDHAF2) is indicated only in patients with those diseases in whom immunohistochemistry tests for SDHB as a surrogate marker to detect the SDH complex mutation yield negative results. Two novel SDHB germline mutations, L157X and P236S, in PGL were previously reported. We therefore examined immunohistochemistry testing for SDHB in the PGLs with the SDHB germline mutations of L157X and P236S.

METHODS

Immunohistochemistry for SDHB was performed in PGLs with the SDHB germline mutations of L157X and P236S. Five cases of sporadic PCC were subject to immunohistochemistry testing for SDHB. Normal tissue from the adrenal cortex adjacent to the sporadic PCC was used as the external positive control.

RESULTS

Immunohistochemistry results were positive for SDHB in PGLs with the SDHB germline mutation of L157X and P236S, all five cases of sporadic PCC, and the adrenal cortex as the external positive control.

CONCLUSION

Immunohistochemistry tests for SDHB showed positivity in PGLs associated with the SDHB germline mutations of L157X and P236S. Thus, immunohistochemistry testing for SDHB might not always reveal a surrogate marker in formal genetic testing of the SDH complex.

A Phase 2, Multicenter Study of Nevanimibe for the Treatment of Congenital Adrenal Hyperplasia

CONTEXT

Patients with classic congenital adrenal hyperplasia (CAH) often require supraphysiologic glucocorticoid doses to suppress adrenocorticotropic hormone (ACTH) and control androgen excess. Nevanimibe hydrochloride (ATR-101), which selectively inhibits adrenal cortex function, might reduce androgen excess independent of ACTH and thus allow for lower glucocorticoid dosing in CAH. 17-hydroxyprogesterone (17-OHP) and androstenedione are CAH biomarkers used to monitor androgen excess.

OBJECTIVE

Evaluate the efficacy and safety of nevanimibe in subjects with uncontrolled classic CAH.

DESIGN

This was a multicenter, single-blind, dose-titration study. CAH subjects with baseline 17-OHP ≥4× the upper limit of normal (ULN) received the lowest dose of nevanimibe for 2 weeks followed by a single-blind 2-week placebo washout. Nevanimibe was gradually titrated up if the primary outcome measure (17-OHP ≤2× ULN) was not met. A total of 5 nevanimibe dose levels were possible (125, 250, 500, 750, 1000 mg twice daily).

RESULTS

The study enrolled 10 adults: 9 completed the study, and 1 discontinued early due to a related serious adverse event. At baseline, the mean age was 30.3 ± 13.8 years, and the maintenance glucocorticoid dose, expressed as hydrocortisone equivalents, was 24.7 ± 10.4 mg/day. Two subjects met the primary endpoint, and 5 others experienced 17-OHP decreases ranging from 27% to 72% during nevanimibe treatment. The most common side effects were gastrointestinal (30%). There were no dose-related trends in adverse events.

CONCLUSIONS

Nevanimibe decreased 17-OHP levels within 2 weeks of treatment. Larger studies of longer duration are needed to further evaluate its efficacy as add-on therapy for CAH.

Non-invasive monitoring of adrenocortical function in female domestic pigs using saliva and faeces as sample matrices

Intensive pig management involves in a commercial setting the housing and implementation of certain procedures, such as castration and tail docking, which may be stressful for the animal. Good farming practices include the reduction of stress due to management processes, but assessing the level of stress perceived entirely through behavioural observations can be challenging. The monitoring stress-related physiological markers, like glucocorticoids (GC), can be an accurate alternative that would presumably be more objective. In order to avoid an additional stressor by taking blood, a non-invasive approach is advisable. We used an adrenocorticotropic hormone (ACTH) stimulation test and the effect of transport to examine the suitability of different enzyme immunoassays (EIAs) for monitoring adrenocortical function in domestic pigs using saliva and faeces as sample matrices. An assay measuring faecal glucocorticoid metabolites (fGCMs) with a 3ß,11ß-diol group has proven suited to determine adrenocortical activity, showing an overall increase of 180% in fGCM concentrations related to ACTH administration and of 70% related to transport, respectively. A cortisol EIA was used to detect salivary glucocorticoid (sGC) concentrations, revealing a 1100% increase in sGC concentrations after ACTH administration. The stability of fGCM concentrations post-defecation was determined to assess possible changes in measured fGCM concentrations in unpreserved faecal material over time, with fGCM concentrations being relatively stable (maximal 12% change) under natural conditions for approximately two days after defecation. This implicates that untreated faecal material from pigs can be analysed for up to two days after collection without appreciable level of depreciation in fGCM concentrations. Being able to assess the physiological stress response of domestic pigs non-invasively can help to improve the well-being of commercially reared pigs.

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.

Immunohistochemistry of the Human Adrenal CYP11B2 in Normal Individuals and in Patients with Primary Aldosteronism

The CYP11B2 enzyme is the terminal enzyme in the biosynthesis of aldosterone. Immunohistochemistry using antibodies against CYP11B2 defines cells of the adrenal ZG that synthesize aldosterone. CYP11B2 expression is normally stimulated by angiotensin II, but becomes autonomous in primary hyperaldosteronism, in most cases driven by recently discovered somatic mutations of ion channels or pumps. Cells expressing CYP11B2 in young normal humans form a continuous band beneath the adrenal capsule; in older individuals they form discrete clusters, aldosterone-producing cell clusters (APCC), surrounded by non-aldosterone producing cells in the outer layer of the adrenal gland. Aldosterone-producing adenomas may exhibit a uniform or heterogeneous expression of CYP11B2. APCC frequently persist in the adrenal with an aldosterone-producing adenoma suggesting autonomous CYP11B2 expression in these cells as well. This was confirmed by finding known mutations that drive aldosterone production in adenomas in the APCC of clinically normal people. Unilateral aldosteronism may also be due to multiple CYP11B2-expressing nodules of various sizes or a continuous band of hyperplastic ZG cells expressing CYP11B2. Use of CYP11B2 antibodies to identify areas for sequencing has greatly facilitated the detection of aldosterone-driving mutations.

Adrenocortical tumorigenesis: Lessons from genetics

Advances in genomics over the past two decades have allowed for elucidation of the genetic alterations leading to the development of adrenocortical tumors and/or hyperplasias. These molecular changes were initially discovered through the study of rare familial tumor syndromes such as McCune-Albright Syndrome, Carney complex, Li-Fraumeni syndrome, and Beckwith-Wiedemann syndrome, with the identification of alterations in genes and molecular pathways that subsequently led to the discovery of aberrations in these or related genes and pathways in sporadic tumors. Genetic alterations in GNAS, PRKAR1A, PRKACA, PRKACB, PDE11A, and PDE8B, that lead to aberrant cyclic adenosine monophosphate-protein (cAMP) kinase A signaling, were found to play a major role in the development of benign cortisol-producing adrenocortical tumors and/or hyperplasias, whereas genetic defects in KCNJ5, ATP1A1, ATP2B3, CACNA1D, CACNA1H, and CLCN2 were implicated in the development of benign aldosterone-producing tumors and/or hyperplasias through modification of intracellular calcium signaling. Germline ARMC5 defects were found to cause the development of primary bilateral macronodular adrenocortical hyperplasia with glucocorticoid and/or mineralocorticoid oversecretion. Adrenocortical carcinoma was linked primarily to aberrant p53 signaling and/or Wnt-β-catenin signaling, as well as IGF2 overexpression, with frequent genetic alterations in TP53, ZNRF3, CTNNB1, and 11p15. This review focuses on the genetic underpinnings of benign cortisol- and aldosterone-producing adrenocortical tumors/hyperplasias and adrenocortical carcinoma.

Targeted Disruption of Lats1 and Lats2 in Mice Impairs Adrenal Cortex Development and Alters Adrenocortical Cell Fate

It has recently been shown that the loss of the Hippo signaling effectors Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) in adrenocortical steroidogenic cells impairs the postnatal maintenance of the adrenal gland. To further explore the role of Hippo signaling in mouse adrenocortical cells, we conditionally deleted the key Hippo kinases large tumor suppressor homolog kinases 1 and -2 (Lats1 and Lats2, two kinases that antagonize YAP and TAZ transcriptional co-regulatory activity) in steroidogenic cells using an Nr5a1-cre strain (Lats1flox/flox;Lats2flox/flox;Nr5a1-cre). We report here that developing adrenocortical cells adopt characteristics of myofibroblasts in both male and female Lats1flox/flox;Lats2flox/flox;Nr5a1-cre mice, resulting in a loss of steroidogenic gene expression, adrenal failure and death by 2 to 3 weeks of age. A marked accumulation of YAP and TAZ in the nuclei of the myofibroblast-like cell population with an accompanying increase in the expression of their transcriptional target genes in the adrenal glands of Lats1flox/flox;Lats2flox/flox;Nr5a1-cre animals suggested that the myofibroblastic differentiation could be attributed in part to YAP and TAZ. Taken together, our results suggest that Hippo signaling is required to maintain proper adrenocortical cell differentiation and suppresses their differentiation into myofibroblast-like cells.

The effects of mitotane and 1α,25-dihydroxyvitamin D3 on Wnt/beta-catenin signaling in human adrenocortical carcinoma cells

PURPOSE

Mitotane is the only chemotherapeutic agent available for the treatment of adrenocortical carcinoma (ACC), however, the anti-neoplastic efficacy is limited due to several side-effects in vivo. There is, therefore, a need of exploring for new anti-tumoral agents which can be used either alone or in combination with mitotane. The active vitamin D metabolite 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) acts as an anti-proliferative agent in human cancer by inhibiting the Wnt/beta-catenin pathway through the vitamin D receptor (VDR). The aim of this study was to study the effects of mitotane and 1α,25(OH)₂D₃, individually or in combination, in an in vitro model with H295R ACC cells, and to elucidate the molecular events behind their effects involving the Wnt/beta-catenin signaling.

METHODS AND RESULTS

Multiple concentrations of mitotane and 1α,25(OH)₂D₃, individually or in combination, were tested on H295R cells for 24-96 h, and the effects analysed by MTT. A reduction in cell growth was observed in a dose/time-dependent manner for both mitotane and 1α,25(OH)₂D₃. In addition, a combination of clinically sub-therapeutic concentrations of mitotane with 1α,25(OH)₂D₃, had an additive anti-proliferative effect (Combination Index = 1.02). In a wound healing assay, individual treatments of both mitotane and 1α,25(OH)₂D₃ reduced the migration ability of H295R cells, with the effect further enhanced on combining both the agents. Western blotting and qRT-PCR analysis showed a modulation of the Wnt/beta-catenin and VDR signaling pathways.

CONCLUSION

Our results show an additive effect of mitotane and 1α,25(OH)₂D₃ on the inhibition of H295R ACC cell growth and viability, and suggest that molecular mechanisms of their effects involve a functional link between VDR and Wnt/beta-catenin pathways.

Regulation of the KCNJ5 gene by SF-1 in the adrenal cortex: Complete genomic organization and promoter function

Activating mutations in the KCNJ5 gene are responsible for the significant number of aldosterone-producing adenomas. To elucidate the molecular mechanisms underlying KCNJ5 expression, we characterized the entire human KCNJ5 gene. The gene spanned approximately 29.8 kb and contained three exons and two introns. The strongest expression of KCNJ5 mRNA was observed in the adrenal gland. The promoter region contained a putative binding site for SF-1 at -1782 bp. A construct containing -2444 bp of the promoter region exhibited the strongest promoter activity in adrenal H295R cells, and the introduction of a mutation in the SF-1 binding site almost completely abolished promoter activity. Furthermore, deletion mutation, EMSA, and knockdown analyses revealed that SF-1 bound to this element and was functional. Immunochemistry showed that KCNJ5 was predominantly expressed in the zona glomerulosa, while SF-1 was ubiquitously expressed in the adrenal cortex. These results demonstrated that SF-1 mediates the expression of human KCNJ5 in the adrenal cortex.

Longitudinal evaluation of glucocorticoid receptor alpha/beta expression and signalling, adrenocortical function and cytokines in critically ill steroid-free patients

PURPOSE

Glucocorticoid actions are mediated by the glucocorticoid receptor (GCR) whose dysfunction leads to glucocorticoid tissue resistance. Our objective was to evaluate GCR-α and GCR-β expression and key steps in the GCR signalling cascade in critical illness.

METHODS

Expression of GCR and major GCR-target genes, cortisol, adrenocorticotropin (ACTH) and cytokines was measured in 42 patients on ICU admission and on days 4, 8, and 13. Twenty-five age- and sex-matched subjects were used as controls.

RESULTS

Acutely, mRNA expression of GCR-α was 10-fold and of GCR-β 3-fold the expression of controls, while during the sub-acute phase expression of both isoforms was lower compared to controls. Expression of FKBP5 and GILZ decreased significantly. Cortisol levels remained elevated and ACTH increased during the 13-day period.

CONCLUSIONS

GCR expression and hypothalamic-pituitary-adrenal axis function undergo a biphasic response during critical illness. The dissociation between low GCR expression and high cortisol implies an abnormal stress response.

ANO4 (Anoctamin 4) Is a Novel Marker of Zona Glomerulosa That Regulates Stimulated Aldosterone Secretion

Microarray comparison of the transcriptomes of human adrenal zona glomerulosa (ZG) and zona fasciculata found several ZG-specific genes that negatively regulate aldosterone secretion. The third and most significantly upregulated ZG-gene (19.9-fold compared with zona fasciculata, P=6.58×10-24) was ANO4, a putative Ca2+-activated chloride channel. We have investigated the role of ANO4 in human adrenal, and whether it functions like the prototype anoctamin, ANO1. We evaluated ANO4 mRNA and protein expression in human adrenal by qPCR and immunohistochemistry, compared the effects of ANO4 and ANO1 overexpression on baseline and stimulated aldosterone secretion and cell proliferation in H295R cells, and analyzed ANO4 activity as a Ca2+-activated chloride channel in comparison with other anoctamins by a fluorescence-based functional assay. The expression of ANO4 in ZG was confirmed by qPCR as 23.21-fold upregulated compared with zona fasciculata (n=18; P=4.93×10-7). Immunohistochemistry found cytoplasmic, ZG-selective expression of ANO4 (anoctamin 4) protein. ANO4 overexpression in H295R cells attenuated calcium-mediated aldosterone secretion and cell proliferation in comparison to controls. The latter effects were in a different direction to those of ANO1. The functional assay showed that, in contrast to ANO1, ANO4 expression results in low levels of calcium-dependent anion transport. In conclusion, ANO4 is one of the most highly expressed genes in ZG. It attenuates stimulated aldosterone secretion and cell proliferation. Although belonging to a family of Ca2+-activated chloride channels, it does not generate significant plasma membrane chloride channel activity.

Correlation Between Differentiation of Adrenocortical Zones and Telomere Lengths Measured by Q-FISH

CONTEXT

Adrenocortical zonation is associated with a markedly complex developmental process, and the pathogenesis and/or etiology of many disorders of adrenocortical zonal development have remained unknown. Cells from the three adrenocortical zones are morphologically and functionally differentiated, and the mature stage of cell development or senescence has been recently reported to be correlated with telomere length. However, the telomere length of each adrenocortical zonal cell has not yet been studied in human adrenal glands.

OBJECTIVE

We aimed to study the telomere lengths of adrenocortical parenchymal cells from three different zones of the adrenal glands present during childhood, adolescence, and adulthood.

METHODS

Adrenal glands of 30 autopsied subjects, aged between 0 and 68 years, were retrieved from pathology files. The normalized telomere to centromere ratio (NTCR), an index of telomere length, was determined in the parenchymal cells of the zona glomerulosa, zona fasciculata, and zona reticularis (ZR), using quantitative fluorescence in situ hybridization.

RESULTS

NTCR of ZR cells was the longest, followed in decreasing order by that of zona glomerulosa and zona fasciculata cells in subjects aged 20 to 68 years, but no substantial differences in NTCR were detected among these three zones in the group <20 years of age. NTCR of ZR increased with age in subjects aged 20 to 68 years, whereas no important age-dependent changes in NTCR were detected in the group <20 years of age.

CONCLUSION

The telomere lengths for three zones in adrenal cortex were correlated with their differentiation in adulthood but not in childhood and adolescence.

Novel high molecular weight albumin-conjugated angiotensin II activates β-arrestin and G-protein pathways

PURPOSE

To study the ability of a novel bovine serum albumin-angiotensin II (BSA-Ang II) conjugate to effect responses of the AT₁ angiotensin II receptor subtype mediated by the G-protein-coupled and the beta-arrestin pathways.

METHODS

Angiotensin II (Ang II) was conjugated with bovine serum albumin and compared with Ang II for competition binding to AT₁ receptors, to stimulate aldosterone release from adrenocortical cells, to promote beta-arrestin binding to AT₁ receptors, to promote calcium mobilization, and stimulate drinking of water and saline by rats.

RESULTS

The BSA-Ang II conjugate was less potent competing for AT₁R binding, but was equally efficacious at stimulating aldosterone release from H295R adrenocortical cells. Both BSA-Ang II and Ang II stimulated calcium mobilization and beta-arrestin binding to AT₁ receptors. BSA-Ang II and Ang II stimulated water appetite equivalently but BSA-Ang II stimulated saline appetite more than Ang II. Both BSA-Ang II and Ang II were considerably more potent at causing calcium mobilization than β-arrestin binding.

CONCLUSIONS

Addition of a high molecular weight molecule to Ang II reduced its AT₁ receptor binding affinity, but did not significantly alter stimulation of aldosterone release or water consumption. The BSA-Ang II conjugate caused a greater saline appetite than Ang II suggesting that it may be a more efficacious agonist of this beta-arrestin-mediated response than Ang II. The higher potency calcium signaling response suggests that the G-protein-coupled responses predominate at physiological concentrations of Ang II, while the beta-arrestin response requires pathophysiological or pharmacological concentrations of Ang II to occur.