Autocrine/paracrine regulatory mechanisms in adrenocortical neoplasms responsible for primary adrenal hypercorticism

Aberrant hormone receptors regulate a wide spectrum of endocrine tumors

Aberrant G-protein coupled receptor (GPCR) expression is highly prevalent in cortisol-secreting primary bilateral macronodular adrenal hyperplasia (PBMAH) and unilateral adenomas. The aberrant expression of diverse GPCRs and their ligands play an important role in the over-function of various endocrine tumours. Examples include aberrant expression of MC2R, 5-HT4R, AVPR1A, LHCGR, and GnRHR in primary aldosteronism; GCGR, LHCGR, and 5-HT4R in phaeochromocytomas and paragangliomas; TRHR, GnRHR, GIPR, and GRP101 in pituitary somatotroph tumours; AVPR2, D2DR, and SSTR5 in pituitary corticotroph tumours; GLP1R, GIPR, and somatostatin receptors in medullary thyroid carcinoma; and SSTRs, GLP1R, and GIPR in other neuroendocrine tumours. The genetic mechanisms causing the ectopic expression of GIPR in cortisol-secreting PBMAHs and unilateral adenomas have been identified, but distinct mechanisms are implicated in other endocrine tumours. Development of functional imaging targeting aberrant GPCRs should be useful for identification and for specific therapies of this wide spectrum of tumours. The aim of this review is to show that the regulation of endocrine tumours by aberrant GPCR is not restricted to cortisol-secreting adrenal lesions, but also occurs in tumours of several other organs.

Mild autonomous cortisol secretion: pathophysiology, comorbidities and management approaches

The majority of incidentally discovered adrenal tumours are benign adrenocortical adenomas and the prevalence of adrenocortical adenomas is around 1-7% on cross-sectional abdominal imaging. These can be non-functioning adrenal tumours or they can be associated with autonomous cortisol secretion on a spectrum that ranges from rare clinically overt adrenal Cushing syndrome to the much more prevalent mild autonomous cortisol secretion (MACS) without signs of Cushing syndrome. MACS is diagnosed (based on an abnormal overnight dexamethasone suppression test) in 20-50% of patients with adrenal adenomas. MACS is associated with cardiovascular morbidity, frailty, fragility fractures, decreased quality of life and increased mortality. Management of MACS should be individualized based on patient characteristics and includes adrenalectomy or conservative follow-up with treatment of associated comorbidities. Identifying patients with MACS who are most likely to benefit from adrenalectomy is challenging, as adrenalectomy results in improvement of cardiovascular morbidity in some, but not all, patients with MACS. Of note, diagnosis and management of patients with bilateral MACS is especially challenging. Current gaps in MACS clinical practice include a lack of specific biomarkers diagnostic of MACS-related health outcomes and a paucity of clinical trials demonstrating the efficacy of adrenalectomy on comorbidities associated with MACS. In addition, little evidence exists to demonstrate the efficacy and safety of long-term medical therapy in patients with MACS.

Evidence of the Role of Inflammation and the Hormonal Environment in the Pathogenesis of Adrenal Myelolipomas in Congenital Adrenal Hyperplasia

Adrenal myelolipomas (AML) are composed of mature adipose and hematopoietic components. They represent approximately 3 percent of adrenal tumors and are commonly found in patients with congenital adrenal hyperplasia (CAH). CAH provides a unique environment to explore AML pathogenesis. We aimed to evaluate the role of the immune system and hormones that accumulate in poorly controlled CAH in the development of AML. When compared to normal adrenal tissue, CAH-affected adrenal tissue and myelolipomas showed an increased expression of inflammatory cells (CD68, IL2Rbeta), stem cells (CD117) B cells (IRF4), and adipogenic markers (aP2/FABP4, AdipoQ, PPARγ, Leptin, CideA), and immunostaining showed nodular lymphocytic accumulation. Immunohistochemistry staining revealed a higher density of inflammatory cells (CD20, CD3, CD68) in CAH compared to non-CAH myelolipomas. In vitro RNA-sequencing studies using NCI-H295R adrenocortical cells with exogenous exposure to ACTH, testosterone, and 17-hydroxyprogesterone hormones, showed the differential expression of genes involved in cell cycle progression, phosphorylation, and tumorigenesis. Migration of B-lymphocytes was initiated after the hormonal treatment of adrenocortical cells using the Boyden chamber chemotaxis assay, indicating a possible hormonal influence on triggering inflammation and the development of myelolipomas. These findings demonstrate the important role of inflammation and the hormonal milieu in the development of AML in CAH.

Clinical, pathophysiologic, genetic and therapeutic progress in Primary Bilateral Macronodular Adrenal Hyperplasia

Patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) usually present bilateral benign adrenocortical macronodules at imaging and variable levels of cortisol excess. PBMAH is a rare cause of primary overt Cushing's syndrome, but may represent up to one third of bilateral adrenal incidentalomas with evidence of cortisol excess. The increased steroidogenesis in PBMAH is often regulated by various G-protein coupled receptors aberrantly expressed in PBMAH tissues; some receptor ligands are ectopically produced in PBMAH tissues creating aberrant autocrine/paracrine regulation of steroidogenesis. The bilateral nature of PBMAH and familial aggregation, led to the identification of germline heterozygous inactivating mutations of the ARMC5 gene, in 20-25% of the apparent sporadic cases and more frequently in familial cases; ARMC5 mutations/pathogenic variants can be associated with meningiomas. More recently, combined germline mutations/pathogenic variants and somatic events inactivating the KDM1A gene were specifically identified in patients affected by GIP-dependent PBMAH. Functional studies demonstrated that inactivation of KDM1A leads to GIP-receptor (GIPR) overexpression and over or down-regulation of other GPCRs. Genetic analysis is now available for early detection of family members of index cases with PBMAH carrying identified germline pathogenic variants. Detailed biochemical, imaging, and co-morbidities assessment of the nature and severity of PBMAH is essential for its management. Treatment is reserved for patients with overt or mild cortisol/aldosterone or other steroid excesses taking in account co-morbidities. It previously relied on bilateral adrenalectomy; however recent studies tend to favor unilateral adrenalectomy, or less frequently, medical treatment with cortisol synthesis inhibitors or specific blockers of aberrant GPCR.

Vascular and hormonal interactions in the adrenal gland

Primary aldosteronism is the most common form of secondary arterial hypertension, due to excessive aldosterone production from the adrenal gland. Although somatic mutations have been identified in aldosterone producing adenoma, the exact mechanisms leading to increased cell proliferation and nodule formation remain to be established. One hypothesis is that changes in vascular supply to the adrenal cortex, due to phenomena of atherosclerosis or high blood pressure, may influence the morphology of the adrenal cortex, resulting in a compensatory growth and nodule formation in response to local hypoxia. In this review, we will summarize our knowledge on the mechanisms regulating adrenal cortex development and function, describe adrenal vascularization in normal and pathological conditions and address the mechanisms allowing the cross-talk between the hormonal and vascular components to allow the extreme tissue plasticity of the adrenal cortex in response to endogenous and exogenous stimuli. We will then address recent evidence suggesting a role for alterations in the vascular compartment that could eventually be involved in nodule formation and the development of primary aldosteronism.

Transcriptomic Response Dynamics of Human Primary and Immortalized Adrenocortical Cells to Steroidogenic Stimuli

Adrenal steroid hormone production is a dynamic process stimulated by adrenocorticotropic hormone (ACTH) and angiotensin II (AngII). These ligands initialize a rapid and robust gene expression response required for steroidogenesis. Here, we compare the predominant human immortalized cell line model, H295R cell, with primary cultures of adult adrenocortical cells derived from human kidney donors. We performed temporally resolved RNA-seq on primary cells stimulated with either ACTH or AngII at multiple time points. The magnitude of the expression dynamics elicited by ACTH was greater than AngII in primary cells. This is likely due to the larger population of adrenocortical cells that are responsive to ACTH. The dynamics of stimulus-induced expression in H295R cells are mostly recapitulated in primary cells. However, there are some expression responses in primary cells absent in H295R cells. These data are a resource for the endocrine community and will help researchers determine whether H295R is an appropriate model for the specific aspect of steroidogenesis that they are studying.

[Bilateral macronodular adrenal hyperplasia: a rare cause of Cushing's syndrome (a case report)]

Bilateral macronodular adrenal hyperplasia (BMAH) is a rare cause of adrenal Cushing's syndrome, accounting for less than 1% of cases. We here report the case of a 48-year-old patient with diabetes and hypertension presenting with clinical signs of Cushing's syndrome. Etiological assessment enabled clinicians to retain the diagnosis of Adrenocorticotropic hormone (ACTH)-independent hypercortisolism associated with BMAH. Unilateral left adrenalectomy was performed based on noriodocholesterol scintigraphy results, with good outcome. However, given the risk of recurrence and cardiovascular complications, long-term monitoring was scheduled.

Primary Aldosteronism: a Continuum from Normotension to Hypertension

PURPOSE OF REVIEW

Primary aldosteronism (PA) is the most common cause of secondary hypertension. Emerging evidence suggests that PA is associated with cardiovascular, metabolic, and renal complications, that likely develop insidiously, due to prolonged inappropriate mineralocorticoid receptor activation. In this review, we discuss the expanding clinical and pathological spectrum of PA.

RECENT FINDINGS

Clinical and molecular studies conducted over the recent years reveal that PA traverses a series of contiguous stages. Pre-clinical, but hormonally overt PA has been identified in patients with normal blood pressure, and such patients harbor an increased risk of developing hypertension. Similarly, genetic and histopathological advancements have exposed a spectrum of PA pathology that corresponds to a continuum that spans from pre-clinical stages to florid PA. PA evolves from pre-hypertensive stages to resistant hypertension, along with serious cardiovascular and renal consequences. Early recognition of PA and targeted therapy will be essential for cardiovascular morbidity and mortality prevention in a large number of patients.

Adrenal Hormone Interactions and Metabolism: A Single Sample Multi-Omics Approach

The adrenal gland is important for many physiological and pathophysiological processes, but studies are often restricted by limited availability of sample material. Improved methods for sample preparation are needed to facilitate analyses of multiple classes of adrenal metabolites and macromolecules in a single sample. A procedure was developed for preparation of chromaffin cells, mouse adrenals, and human chromaffin tumors that allows for multi-omics analyses of different metabolites and preservation of native proteins. To evaluate the new procedure, aliquots of samples were also prepared using conventional procedures. Metabolites were analyzed by liquid-chromatography with mass spectrometry or electrochemical detection. Metabolite contents of chromaffin cells and tissues analyzed with the new procedure were similar or even higher than with conventional methods. Catecholamine contents were comparable between both procedures. The TCA cycle metabolites, cis-aconitate, isocitate, and α-ketoglutarate were detected at higher concentrations in cells, while in tumor tissue only isocitrate and potentially fumarate were measured at higher contents. In contrast, in a broad untargeted metabolomics approach, a methanol-based preparation procedure of adrenals led to a 1.3-fold higher number of detected metabolites. The established procedure also allows for simultaneous investigation of adrenal hormones and related enzyme activities as well as proteins within a single sample. This novel multi-omics approach not only minimizes the amount of sample required and overcomes problems associated with tissue heterogeneity, but also provides a more complete picture of adrenal function and intra-adrenal interactions than previously possible.

Role of unilateral adrenalectomy in bilateral adrenal hyperplasias with Cushing's syndrome

Primary bilateral adrenocortical hyperplasias are rare forms of pituitary ACTH-independent Cushing's syndrome (CS). They are divided between primary bilateral macronodular adrenal hyperplasia (PBMAH) and micronodular adrenal hyperplasia (MiBAH), which is subdivided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). One of the most debated aspects surrounding these entities is their most appropriate therapy. Although bilateral adrenalectomy (BA) has previously been the most utilized therapy for patients with overt CS, recent studies have indicated that unilateral adrenalectomy (UA) can be effective in patients with PBMAH and some with MiBAH with fewer long-term side effects. Medical therapies can also be used for bridging to surgery or rarely in the long-term for these patients. We review the various degrees of CS resulting from PBMAH and MiBAH, with a special focus on their respective therapies including UA, taking into account the recent pathophysiological and genetics findings.

Aldosterone-Regulating Receptors and Aldosterone-Driver Somatic Mutations

BACKGROUND

Somatic gene mutations that facilitate inappropriate intracellular calcium entrance have been identified in most aldosterone-producing adenomas (APAs). Studies suggest that angiotensin II and adrenocorticotropic hormone (ACTH) augment aldosterone production from APAs. Little is known, however, regarding possible variations in response to hormonal stimuli between APAs with different aldosterone-driver mutations.

OBJECTIVE

To analyze the transcript expression of type 1 angiotensin II receptors (AGTR1), ACTH receptors (MC2R), and melanocortin 2 receptor accessory protein (MRAP) in APAs with known aldosterone-driver somatic mutations.

METHODS

RNA was isolated from APAs with mutations in: KCNJ5 (n = 14), ATP1A1 (n = 14), CACNA1D (n = 14), and ATP2B3 (n = 5), and from normal adjacent adrenal tissue (n = 45). Transcript expression of MC2R, MRAP, AGTR1, aldosterone synthase (CYP11B2), 17α-hydroxylase/17,20-lyase (CYP17A1), and 11β-hydroxylase (CYP11B1) were quantified using quantitative RT-PCR and normalized to β-actin.

RESULTS

Compared to adjacent normal adrenal tissue, APAs had higher transcript levels of CYP11B2 (2,216.4 [1,112.0, 2,813.5]-fold, p < 0.001), MC2R (2.88 [2.00, 4.52]-fold, p < 0.001), and AGTR1 (1.80 [1.02, 2.80]-fold, p < 0.001]), and lower transcript levels of MRAP, CYP17A1, and CYP11B1 (0.28-0.36, p < 0.001 for all). MC2R and CYP11B2 transcripts were lower in APAs with KCNJ5 vs. other mutations (p < 0.01 for both). MC2R expression correlated positively with that of AGTR1 in APAs harboring KCNJ5 and CACNA1D mutations, and with MRAP expression in APAs harboring ATPase mutations.

CONCLUSIONS

While MC2R and AGTR1 are expressed in all APAs, differences were observed based on the underlying aldosterone-driver somatic mutations. In tandem, our findings suggest that APAs with ATPase-mutations are more responsive to ACTH than KCNJ5-mutated APAs.

Glucocorticoid Excess in Patients with Pheochromocytoma Compared with Paraganglioma and Other Forms of Hypertension

CONTEXT

Catecholamines and adrenocortical steroids are important regulators of blood pressure. Bidirectional relationships between adrenal steroids and catecholamines have been established but whether this is relevant to patients with pheochromocytoma is unclear.

OBJECTIVE

This study addresses the hypothesis that patients with pheochromocytoma and paraganglioma (PPGL) have altered steroid production compared with patients with primary hypertension.

DESIGN

Multicenter cross-sectional study.

SETTING

Twelve European referral centers.

PATIENTS

Subjects included 182 patients with pheochromocytoma, 36 with paraganglioma and 270 patients with primary hypertension. Patients with primary aldosteronism (n = 461) and Cushing syndrome (n = 124) were included for additional comparisons.

INTERVENTION

In patients with PPGLs, surgical resection of tumors.

OUTCOME MEASURES

Differences in mass spectrometry-based profiles of 15 adrenal steroids between groups and after surgical resection of PPGLs. Relationships of steroids to plasma and urinary metanephrines and urinary catecholamines.

RESULTS

Patients with pheochromocytoma had higher (P < .05) circulating concentrations of cortisol, 11-deoxycortisol, 11-deoxycorticosterone, and corticosterone than patients with primary hypertension. Concentrations of cortisol, 11-deoxycortisol, and corticosterone were also higher (P < .05) in patients with pheochromocytoma than with paraganglioma. These steroids correlated positively with plasma and urinary metanephrines and catecholamines in patients with pheochromocytoma, but not paraganglioma. After adrenalectomy, there were significant decreases in cortisol, 11-deoxycortisol, corticosterone, 11-deoxycorticosterone, aldosterone, and 18-oxocortisol.

CONCLUSIONS

This is the first large study in patients with PPGLs that supports in a clinical setting the concept of adrenal cortical-medullary interactions involving an influence of catecholamines on adrenal steroids. These findings could have implications for the cardiovascular complications of PPGLs and the clinical management of patients with the tumors.

The neuropeptide substance P regulates aldosterone secretion in human adrenals

Aldosterone, produced by the adrenals and under the control of plasma angiotensin and potassium levels, regulates hydromineral homeostasis and blood pressure. Here we report that the neuropeptide substance P (SP) released by intraadrenal nerve fibres, stimulates aldosterone secretion via binding to neurokinin type 1 receptors (NK1R) expressed by aldosterone-producing adrenocortical cells. The action of SP is mediated by the extracellular signal-regulated kinase pathway and involves upregulation of steroidogenic enzymes. We also conducted a prospective proof-of-concept, double blind, placebo-controlled clinical trial aimed to investigate the impact of the NK1R antagonist aprepitant on aldosterone secretion in healthy male volunteers (EudraCT: 2008-003367-40, ClinicalTrial.gov: NCT00977223). Participants received during two 7-day treatment periods aprepitant (125 mg on the 1^st day and 80 mg during the following days) or placebo in a random order at a 2-week interval. The primary endpoint was plasma aldosterone levels during posture test. Secondary endpoints included basal aldosterone alterations, plasma aldosterone variation during metoclopramide and hypoglycaemia tests, and basal and stimulated alterations of renin, cortisol and ACTH during the three different stimulatory tests. The safety of the treatment was assessed on the basis of serum transaminase measurements on days 4 and 7. All pre-specified endpoints were achieved. Aprepitant decreases aldosterone production by around 30% but does not influence the aldosterone response to upright posture. These results indicate that the autonomic nervous system exerts a direct stimulatory tone on mineralocorticoid synthesis through SP, and thus plays a role in the maintenance of hydromineral homeostasis. This regulatory mechanism may be involved in aldosterone excess syndromes.

Adrenal aldosterone production is regulated by plasma angiotensin and potassium levels. Here the authors report that the neuropeptide substance P stimulates aldosterone production via neurokinin type 1 receptors (NK1R), and report a proof-of-concept placebo controlled clinical trial showing that a NK1R antagonist decreases aldosterone levels.

Adrenocortical hyperplasia: A multifaceted disease

Adrenocortical hyperplasia may develop in different contexts. Primary adrenal hyperplasia may be secondary to primary bilateral macronodular adrenocortical hyperplasia (PBMAH) or micronodular bilateral adrenal hyperplasia (MiBAH) which may be divided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). Both lead to oversecretion of cortisol and potentially to Cushing's syndrome. Moreover, adrenocortical hyperplasia may be secondary to longstanding ACTH stimulation in ACTH oversecretion as in Cushing's disease, ectopic ACTH secretion or glucocorticoid resistance syndrome and congenital adrenal hyperplasia secondary to various enzymatic defects within the cortex. Finally, idiopathic bilateral adrenal hyperplasia is the most common cause of primary aldosteronism. We will discuss recent findings on the multifaceted forms of adrenocortical hyperplasia.

Aberrant G-protein coupled hormone receptor in adrenal diseases

The regulation of cortisol or aldosterone production when ACTH of pituitary origin or the renin-angiotensin systems are suppressed in primary adrenal Cushing's syndrome or in primary aldosteronism is exerted by diverse genetic and molecular mechanisms. In addition to recently identified mutations in various genes implicated in the cyclic AMP or ion channel pathways, steroidogenesis is not really autonomous as it is frequently regulated by the aberrant adrenocortical expression of diverse hormone receptors, particularly G-protein coupled hormone receptors (GPCR) which can substitute for the normal function of ACTH or angiotensin-II. In addition, paracrine or autocrine production of ligands for the aberrant GPCR such as ACTH or serotonin is found in some adrenal tumors or hyperplasias and participates in a complex regulatory loop causing steroid excess. Targeted therapies to block the aberrant ligands or their receptors could become useful in the future, particularly for patients with bilateral source of steroid excess.

Tumor microenvironment in functional adrenocortical adenomas: immune cell infiltration in cortisol-producing adrenocortical adenoma

The tumor microenvironment plays pivotal roles in various human neoplasms. However, that of benign tumor, particularly hormone-secreting endocrine tumors, has remained virtually unknown. Therefore, we firstly attempted to analyze the tumor microenvironment of autonomous hormone-secreting adrenocortical adenomas. We first histologically evaluated 21 cortisol-producing adrenocortical adenoma (CPA) and 13 aldosterone-producing adrenocortical adenoma (APA) cases. Quantitative histologic analysis revealed that intratumoral immune cell infiltration (ICI) was more pronounced in CPAs than in APAs. We then evaluated the cytokine and chemokine profiles using polymerase chain reaction arrays in APAs and CPAs. Angiogenic chemokines, C-X-C motif chemokine ligand (CXCL) 1 and CXCL2, were significantly more abundant in CPAs than in APAs using subsequent quantitative polymerase chain reaction and immunohistochemical analyses. We then examined the vascular density between these 2 adenomas, and the density was significantly higher in overt CPAs than in APAs. Of particular interest, CXCL12-positive vessels were detected predominantly in CPAs, and their infiltrating immune cells were C-X-C motif chemokine receptor 4 (CXCR4) positive. These results above indicated that CXCL12-CXCR4 signaling could partly account for ICI detected predominantly in CPAs. We then further explored the etiology of ICI in CPAs by evaluating the senescence of tumor cells possibly caused by excessive cortisol in CPAs. The status of senescence markers, p16 and p21, was significantly more abundant in CPAs than in APAs. In addition, all CPA cases examined were positive for senescence-associated β-galactosidase. These results all indicated that exposure to local excessive cortisol could result in senescence of tumors cells and play essential roles in constituting the characteristic tissue microenvironment of CPAs.

Genetic Causes of Functional Adrenocortical Adenomas

Aldosterone and cortisol, the main mineralocorticoid and glucocorticoid hormones in humans, are produced in the adrenal cortex, which is composed of three concentric zones with specific functional characteristics. Adrenocortical adenomas (ACAs) can lead to the autonomous secretion of aldosterone responsible for primary aldosteronism, the most frequent form of secondary arterial hypertension. In the case of cortisol production, ACAs lead to overt or subclinical Cushing syndrome. Genetic analysis driven by next-generation sequencing technology has enabled the discovery, during the past 7 years, of the genetic causes of a large subset of ACAs. In particular, somatic mutations in genes regulating intracellular ionic homeostasis and membrane potential have been identified in aldosterone-producing adenomas. These mutations all promote increased intracellular calcium concentrations, with activation of calcium signaling, the main trigger for aldosterone production. In cortisol-producing adenomas, recurrent somatic mutations in PRKACA (coding for the cyclic adenosine monophosphate-dependent protein kinase catalytic subunit α) affect cyclic adenosine monophosphate-dependent protein kinase A signaling, leading to activation of cortisol biosynthesis. In addition to these specific pathways, the Wnt/β-catenin pathway appears to play an important role in adrenal tumorigenesis, because β-catenin mutations have been identified in both aldosterone- and cortisol-producing adenomas. This, together with different intermediate states of aldosterone and cortisol cosecretion, raises the possibility that the two conditions share a certain degree of genetic susceptibility. Alternatively, different hits might be responsible for the diseases, with one hit leading to adrenocortical cell proliferation and nodule formation and the second specifying the hormonal secretory pattern.

Role of cAMP/PKA pathway and T-type calcium channels in the mechanism of action of serotonin in human adrenocortical cells

In human adrenal, serotonin (5-HT), produced by mast cells located in zona glomerulosa, stimulates production of corticosteroids through a paracrine mechanism involving the 5-HT receptor type 4 (5-HT₄). The aim of the present study was to investigate the transduction mechanisms associated with activation of 5-HT₄ receptors in human adrenocortical cells. Our results show that 5-HT₄ receptors are present in the outer adrenal cortex, both in glomerulosa and fasciculata zonae. In the zona glomerulosa. 5-HT₄ receptor was detected both in immunopositive and immunonegative cells for 11β-hydroxylase, an enzyme involved in cortisol synthesis. The data demonstrate that 5-HT₄ receptors are positively coupled to adenylyl cyclases and cAMP-dependent protein kinases (PKA). The activation of the cAMP-PKA pathway is associated with calcium influx through T-type calcium channels. Both the adenylyl cyclase/PKA pathway and the calcium influx are involved in 5-HT-induced cortisol secretion.

Functional Implications of LH/hCG Receptors in Pregnancy-Induced Cushing Syndrome

Context:

Elevated human choriogonadotropin (hCG) may stimulate aberrantly expressed luteinizing hormone (LH)/hCG receptor (LHCGR) in adrenal glands, resulting in pregnancy-induced bilateral macronodular adrenal hyperplasia and transient Cushing syndrome (CS).

Objective:

To determine the role of LHCGR in transient, pregnancy-induced CS.

Design, Setting, Patient, and Intervention:

We investigated the functional implications of LHCGRs in a patient presenting, at a tertiary referral center, with repeated pregnancy-induced CS with bilateral adrenal hyperplasia, resolving after parturition.

Main Outcome Measures and Results:

Acute testing for aberrant hormone receptors was negative except for arginine vasopressin (AVP)–increased cortisol secretion. Long-term hCG stimulation induced hypercortisolism, which was unsuppressed by dexamethasone. Postadrenalectomy histopathology demonstrated steroidogenically active adrenocortical hyperplasia and ectopic cortical cell clusters in the medulla. Quantitative polymerase chain reaction showed upregulated expression of LHCGR, transcription factors GATA4, ZFPM2, and proopiomelanocortin (POMC), AVP receptors (AVPRs) AVPR1A and AVPR2, and downregulated melanocortin 2 receptor (MC2R) vs control adrenals. LHCGR was localized in subcapsular, zona glomerulosa, and hyperplastic cells. Single adrenocorticotropic hormone–positive medullary cells were demonstrated in the zona reticularis. The role of adrenal adrenocorticotropic hormone was considered negligible due to downregulated MC2R. Coexpression of CYP11B1/CYP11B2 and AVPR1A/AVPR2 was observed in ectopic cortical cells in the medulla. hCG stimulation of the patient’s adrenal cell cultures significantly increased cyclic adenosine monophosphate, corticosterone, 11-deoxycortisol, cortisol, and androstenedione production. CTNNB1, PRKAR1A, ARMC5, and PRKACA gene mutational analyses were negative.

Conclusion:

Nongenetic, transient, somatic mutation-independent, pregnancy-induced CS was due to hCG-stimulated transformation of LHCGR-positive undifferentiated subcapsular cells (presumably adrenocortical progenitors) into LHCGR-positive hyperplastic cortical cells. These cells respond to hCG stimulation with cortisol secretion. Without the ligand, they persist with aberrant LHCGR expression and the ability to respond to the same stimulus.

Modulation of the circadian clock by glucocorticoid receptor isoforms in the H295R cell line

Peripheral clocks are set by different nervous, hormonal and metabolic stimuli, and regulate the circadian expression of several genes. We investigated whether a peripheral clock could be induced in the human adrenocortical cell line H295R and whether glucocorticoid receptor isoforms (GRα and GRß) are involved in this clock system. After synchronization of cells with serum shock, the rhythmic oscillation of clock genes PER1, PER2, REV-ERBα, and ARNTL was confirmed. In addition, H295R cells even without serum shock showed rhythmic expression of PER1, PER2, CRY1 and ARNTL. Glucocorticoid treatment induced a rapid response of PER1, PER2 and CRY1 in a GRα-dependent manner. Continuous glucocorticoid stimulation after 6h caused suppression of REV-ERBα. Administration of a GR antagonist, RU486, disrupted the circadian oscillation of clock genes and prevented the acute changes in PER1, PER2 and CRY1 levels. Overexpression of the GRß isoform alone did not alter the expression of the examined clock genes, but did prevent the GRα-related suppression of REV-ERBα. These alterations occurred independently from ACTH and CRH. Our data demonstrate that a peripheral clock system is present in a human adrenocortical cell line and that periodic oscillations of clock genes are influenced by glucocorticoids, mainly through GRα.

Local Control of Aldosterone Production and Primary Aldosteronism

Primary aldosteronism (PA) is caused by excessive production of aldosterone by the adrenal cortex and is determined by a benign aldosterone-producing adenoma (APA) in a significant proportion of cases. Local mechanisms, as opposed to circulatory ones, that control aldosterone production in the adrenal cortex are particularly relevant in the physiopathological setting and in the pathogenesis of PA. A breakthrough in our understanding of the pathogenetic mechanisms in APA has been the identification of somatic mutations in genes controlling membrane potential and intracellular calcium concentrations. However, recent data show that the processes of nodule formation and aldosterone hypersecretion can be dissociated in pathological adrenals and suggest a model envisaging different molecular events for the pathogenesis of APA.

Adrenal Gland Microenvironment and Its Involvement in the Regulation of Stress-Induced Hormone Secretion during Sepsis

Survival of all living organisms depends on maintenance of a steady state of homeostasis, which process relies on its ability to react and adapt to various physical and emotional threats. The defense against stress is executed by the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal medullary system. Adrenal gland is a major effector organ of stress system. During stress, adrenal gland rapidly responds with increased secretion of glucocorticoids (GCs) and catecholamines into circulation, which hormones, in turn, affect metabolism, to provide acutely energy, vasculature to increase blood pressure, and the immune system to prevent it from extensive activation. Sepsis resulting from microbial infections is a sustained and extreme example of stress situation. In many critical ill patients, levels of both corticotropin-releasing hormone and adrenocorticotropin, the two major regulators of adrenal hormone production, are suppressed. Levels of GCs, however, remain normal or are elevated in these patients, suggesting a shift from central to local intra-adrenal regulation of adrenal stress response. Among many mechanisms potentially involved in this process, reduced GC metabolism and activation of intra-adrenal cellular systems composed of adrenocortical and adrenomedullary cells, endothelial cells, and resident and recruited immune cells play a key role. Hence, dysregulated function of any of these cells and cellular compartments can ultimately affect adrenal stress response. The purpose of this mini review is to highlight recent insights into our understanding of the adrenal gland microenvironment and its role in coordination of stress-induced hormone secretion.

Role of ACTH in the Interactive/Paracrine Regulation of Adrenal Steroid Secretion in Physiological and Pathophysiological Conditions

In the normal human adrenal gland, steroid secretion is regulated by a complex network of autocrine/paracrine interactions involving bioactive signals released by endothelial cells, nerve terminals, chromaffin cells, immunocompetent cells, and adrenocortical cells themselves. ACTH can be locally produced by medullary chromaffin cells and is, therefore, a major mediator of the corticomedullary functional interplay. Plasma ACTH also triggers the release of angiogenic and vasoactive agents from adrenocortical cells and adrenal mast cells and, thus, indirectly regulates steroid production through modulation of the adrenal blood flow. Adrenocortical neoplasms associated with steroid hypersecretion exhibit molecular and cellular defects that tend to reinforce the influence of paracrine regulatory loops on corticosteroidogenesis. Especially, ACTH has been found to be abnormally synthesized in bilateral macronodular adrenal hyperplasia responsible for hypercortisolism. In these tissues, ACTH is detected in a subpopulation of adrenocortical cells that express gonadal markers. This observation suggests that ectopic production of ACTH may result from impaired embryogenesis leading to abnormal maturation of the adrenogonadal primordium. Globally, the current literature indicates that ACTH is a major player in the autocrine/paracrine processes occurring in the adrenal gland in both physiological and pathological conditions.

Role of ACTH and Other Hormones in the Regulation of Aldosterone Production in Primary Aldosteronism

The major physiological regulators of aldosterone production from the adrenal zona glomerulosa are potassium and angiotensin II; other acute regulators include adrenocorticotropic hormone (ACTH) and serotonin. Their interactions with G-protein coupled hormone receptors activate cAMP/PKA pathway thereby regulating intracellular calcium flux and CYP11B2 transcription, which is the specific steroidogenic enzyme of aldosterone synthesis. In primary aldosteronism (PA), the increased production of aldosterone and resultant relative hypervolemia inhibits the renin and angiotensin system; aldosterone secretion is mostly independent from the suppressed renin-angiotensin system, but is not autonomous, as it is regulated by a diversity of other ligands of various eutopic or ectopic receptors, in addition to activation of calcium flux resulting from mutations of various ion channels. Among the abnormalities in various hormone receptors, an overexpression of the melanocortin type 2 receptor (MC2R) could be responsible for aldosterone hypersecretion in aldosteronomas. An exaggerated increase in plasma aldosterone concentration (PAC) is found in patients with PA secondary either to unilateral aldosteronomas or bilateral adrenal hyperplasia (BAH) following acute ACTH administration compared to normal individuals. A diurnal increase in PAC in early morning and its suppression by dexamethasone confirms the increased role of endogenous ACTH as an important aldosterone secretagogue in PA. Screening using a combination of dexamethasone and fludrocortisone test reveals a higher prevalence of PA in hypertensive populations compared to the aldosterone to renin ratio. The variable level of MC2R overexpression in each aldosteronomas or in the adjacent zona glomerulosa hyperplasia may explain the inconsistent results of adrenal vein sampling between basal levels and post ACTH administration in the determination of source of aldosterone excess. In the rare cases of glucocorticoid remediable aldosteronism, a chimeric CYP11B2 becomes regulated by ACTH activating its chimeric CYP11B1 promoter of aldosterone synthase in bilateral adrenal fasciculate-like hyperplasia. This review will focus on the role of ACTH on excess aldosterone secretion in PA with particular focus on the aberrant expression of MC2R in comparison with other aberrant ligands and their GPCRs in this frequent pathology.

Endothelial immunomediated reactivity in acute cardiac ischaemia: Role of endothelin 1, interleukin 8 and NT-proBNP in patients affected by unstable angina pectoris

The role of endothelium in the progression of atheromasic disease has already been demonstrated. Endothelin-1 (ET-1) is released from endothelial cells during acute and chronic vascular damage and it appears to be the strongest vasoconstrictor agent known.The aim of this study is to investigate the amount of endothelial damage in patients with unstable angina (UA), as defined by serum levels of ET-1, to verify a possible correlation with increased ischaemic damage by evaluation of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) and interleukin 8 (IL-8) levels.Serum levels of ET-1, IL-8 and NT-proBNP obtained from 10 patients affected by low-risk UA were compared to those belonging to eight healthy subjects. In order to compare the laboratory data pertaining to the two populations, a Student's t-test and a Mann-Whitney U test were performed.Levels of ET-1, IL-8 and NT-proBNP in samples of peripheral blood of patients affected by UA were significantly elevated, compared with those of the control group. The linear correlation analysis demonstrated a positive and significant correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP in subjects affected by UA.Early elevated levels of ET-1, IL-8 and NT-proBNP in patients with UA show a coexistence between ischaemic insults and endothelial damages. A positive and significant linear correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP confirms that an increased ischaemic insult is correlated to inflammation signs and endothelium damage signs.In patients with UA, ischaemia is always associated with a systemic immuno-mediated activity induced by acute endothelial damage. We suggest early administration of ET-1-selective receptor blockers and anti-inflammatory drugs.

Paracrine control of steroidogenesis by serotonin in adrenocortical neoplasms

Serotonin (5-hydroxytryptamine; 5-HT) is able to activate the hypothalamo-pituitary-adrenal axis via multiple actions at different levels. In the human adrenal gland, 5-HT, released by subcapsular mast cells, stimulates corticosteroid production through a paracrine mode of communication which involves 5-HT receptor type 4 (5-HT4) primarily located in zona glomerulosa. As a result, 5-HT is much more efficient to stimulate aldosterone secretion than cortisol release in vitro and administration of 5-HT4 receptor agonists to healthy individuals is followed by an increase in plasma aldosterone levels without any change in plasma cortisol concentrations. Interestingly, adrenocortical hyperplasias and tumors responsible for corticosteroid hypersecretion exhibit various cellular and molecular defects which tend to reinforce the intraadrenal serotonergic tone. These pathophysiological mechanisms, which are summarized in the present review, include an increase in adrenal 5-HT production and overexpression of 5-HT receptors in adrenal neoplastic tissues. Altogether, these data support the concept of adrenal serotonergic paracrinopathy and suggest that 5-HT and its receptors may constitute valuable targets for pharmacological treatments of primary adrenal diseases.

[New insights in adrenal Cushing syndrome]

The development of molecular biology tools has allowed major advances in the genetic determinism and the pathophysiology of pheochromocytomas and Conn's adenomas. However, the molecular pathophysiology of ACTH-independent Cushing's Syndrome was mostly unknown until recently. In 2014, major new insights concerning the physiopathology of ACTH-independent macronodular adrenal hyperplasias (AIMAH) and the cortisol-secreting adenomas have been published. Elsewhere, the cardiovascular consequences of the subclinical hypercortisolism due to adrenal incidentalomas, was described only in some cross-sectional studies. The natural history of these lesions has been documented in two large follow-up studies. These new data presented during the Endocrine Congress are summarized herein.

Genetics of primary macronodular adrenal hyperplasia

ACTH-independent macronodular adrenal hyperplasia is a rare cause of Cushing's syndrome (CS), accounting for <2% of all endogenous CS cases; however it is more frequently identified incidentally with sub-clinical cortisol secretion. Recently, cortisol secretion has been shown to be regulated by ectopic corticotropin, which is in turn produced by clusters of steroidogenic cells of the hyperplastic adrenal nodules. Hence, the term 'ACTH-independent' is not entirely appropriate for this disorder. Accordingly, the disease is designated primary macronodular adrenal hyperplasia (PMAH) in this review article. The means by which cortisol production is regulated in PMAH despite the suppressed levels of ACTH of pituitary origin is exceedingly complex. Several molecular events have been proposed to explain the enhanced cortisol secretion, increased cell proliferation, and nodule formation in PMAH. Nonetheless, the precise sequence of events and the molecular mechanisms underlying this condition remain unclear. The purpose of this review is therefore to present new insights on the molecular and genetic profile of PMAH pathophysiology, and to discuss the implications for disease progression.

Cell-to-cell communication in bilateral macronodular adrenal hyperplasia causing hypercortisolism

It has been well established that, in the human adrenal gland, cortisol secretion is not only controlled by circulating corticotropin but is also influenced by a wide variety of bioactive signals, including conventional neurotransmitters and neuropeptides, released within the cortex by various cell types such as chromaffin cells, neurons, cells of the immune system, adipocytes, and endothelial cells. These different types of cells are present in bilateral macronodular adrenal hyperplasia (BMAH), a rare etiology of primary adrenal Cushing's syndrome, where they appear intermingled with adrenocortical cells in the hyperplastic cortex. In addition, the genetic events, which cause the disease, favor abnormal adrenal differentiation that results in illicit expression of paracrine regulatory factors and their receptors in adrenocortical cells. All these defects constitute the molecular basis for aberrant autocrine/paracrine regulatory mechanisms, which are likely to play a role in the pathophysiology of BMAH-associated hypercortisolism. The present review summarizes the current knowledge on this topic as well as the therapeutic perspectives offered by this new pathophysiological concept.

Common genetic variants of the human steroid 21-hydroxylase gene (CYP21A2) are related to differences in circulating hormone levels

Purpose

Systematic evaluation of the potential relationship between the common genetic variants of CYP21A2 and hormone levels.

Methods

The relationships of CYP21A2 intron 2 polymorphisms and haplotypes with diverse baseline and stimulated blood hormone levels were studied in 106 subjects with non-functioning adrenal incidentaloma (NFAI). The rationale for using NFAI subjects is dual: i) their baseline hormone profiles do not differ from those of healthy subjects and ii) hormone levels after stimulation tests are available.

Results

The carriers (N = 27) of a well-defined CYP21A2 haplotype cluster (c5) had significantly elevated levels of cortisol (p = 0.0110), and 17-hydroxyprogesterone (p = 0.0001) after ACTH stimulation, and 11-deoxycortisol after metyrapone administration (p = 0.0017), but the hormone values were in normal ranges. In addition, the carriers (N = 33) of the C allele of the rs6462 polymorphism had a higher baseline aldosterone level (p = 0.0006). The prevalence of these genetic variants of CYP21A2 did not differ between NFAI and healthy subjects.

Conclusions

The common CYP21A2 variants presumably exert the same effect on hormone levels in the healthy and disease-affected populations. Therefore, they may contribute to complex diseases such as some cardiovascular diseases, and may influence the genotype-phenotype correlation in patients with congenital adrenal hyperplasia (CAH) including the individual need for hormone substitution.

Autocrine positive regulatory feedback of glucocorticoid secretion: glucocorticoid receptor directly impacts H295R human adrenocortical cell function

Glucocorticoid receptor (GR), a ubiquitous transcriptional factor, regulates target gene expression upon activation by glucocorticoids, notably cortisol, a corticosteroid hormone synthesized in the adrenal cortex. We thus hypothesized that both GR and cortisol might be involved in the regulation of adrenal physiology and steroidogenesis in an autocrine manner. In a cortisol-secreting human adrenocortical cell line (H295R), the GR-dependent signaling pathway was pharmacologically modulated either by dexamethasone (DEX), a GR agonist or by RU486, a GR antagonist, or was knocked-down by small interfering RNA strategy (SiRNA). We showed that GR activation, elicited by 48 h exposure to DEX, exerts a global positive regulatory effect on adrenal steroidogenesis as revealed by a 1.5- to 2-fold increase in cortisol, 11-deoxycortisol and 17-hydroxyprogesterone secretion associated with a significant enhanced expression of steroidogenesis factors such as StAR, CYP11A1, CYP21A2 and CYP11B1. In sharp contrast, RU486 treatment exerted opposite effects by decreasing both steroid production and expression of these steroidogenic factors. Likewise, GR repression by SiRNA also significantly reduced StAR, CYP11A1, and CYP11B1 mRNA levels. Interestingly, RU486 resulted in a significant CYP21A2 enzymatic blockade as demonstrated by a massive increase in 17-hydroxyprogesterone concentrations in RU486-treated H295R cell supernatants, while cortisol and 11-deoxycortisol secretions were reduced by more than 60%. Consistently, we also demonstrated that metabolic conversion of 17-hydroxyprogesterone into 11-deoxycortisol onto H295R cells was drastically blunted in the presence of RU 486. Finally, steady state levels of MC2R transcripts encoding for the ACTH receptor were significantly induced by DEX, unlikely through a direct GR-mediated transcriptional activation as opposed to CYP11A1 and FKBP5 target genes. These results could account for a higher glucocorticoid-elicited ACTH sensitivity of adrenocortical cells. Our study identifies a positive ultra-short regulatory loop exerted by GR on steroidogenesis in H295R cells, thus supporting a complex intra-adrenal GR-mediated feedback, likely relevant for human adrenocortical pathologies.

Contributing role of extracellular vesicles on vascular endothelium haemostatic balance in cancer

Extracellular vesicles (EVs) generated during tumourigenesis are thought to play a major role in the hypercoagulant state observed in cancer patients. They exhibit negatively charged phospholipids and tissue factor (TF) that promote coagulation cascade activation. In addition, they contain surface proteins and cytoplasmic molecules, both originating from the producing cell that can impact target cells’ expression. By targeting endothelial cells of blood vessels, these EVs could disturb the physiological anticoagulant properties of these cells and be partly responsible for the vascular endothelium activation observed in cancer patients. Indeed, vascular endothelium naturally exhibits heparin-like proteoglycan, TF pathway inhibitor and protein C anticoagulant pathway that prevent thrombosis in physiological condition. An overexpression of TF and a decreased expression of coagulation cascade inhibitors have been reported after EVs’ treatment of endothelial cells. The induction of apoptosis and an increased expression of platelet adhesion molecules have also been highlighted. These events may promote thrombus formation in cancer. The aim of this paper is to provide a targeted review on the current evidence and knowledge of roles and impact of EVs on endothelial surface anticoagulant and procoagulant factors and cellular adhesion molecules expression.

Primary bilateral macronodular adrenal hyperplasia

PURPOSE OF REVIEW

Primary bilateral macronodular adrenal hyperplasia is a rare cause of Cushing's syndrome and is more often diagnosed as bilateral adrenal incidentalomas with subclinical cortisol production. We summarize the recent insights concerning its epidemiology, diagnosis, genetics, pathophysiology, and therapeutic options.

RECENT FINDINGS

Recent publications have modified our notions on the genetics and pathophysiology of bilateral macronodular adrenal hyperplasia. Combined germline and somatic mutations of armadillo repeat containing 5 gene were identified in familial cases, in approximately 50% of apparently sporadic cases and in the relatives of index cases; genetic testing should allow early diagnosis in the near future. The recent finding of ectopic adrenocortical production of adrenocorticotropic hormone in clusters of bilateral macronodular adrenal hyperplasia tissues and its regulation by aberrant hormone receptors opens new horizons for eventual medical therapy using melanocortin-2 receptor and G-protein-coupled receptor antagonists. Finally, some medical and surgical treatments have been updated.

SUMMARY

Recent findings indicate that bilateral macronodular adrenal hyperplasia is more frequently genetically determined than previously believed. Considering the role of paracrine adrenocorticotropic hormone production on cortisol secretion, the previous nomenclature of adrenocorticotropic hormone-independent macronodular adrenal hyperplasia appears inappropriate, and this disease should now be named primary bilateral macronodular adrenal hyperplasia.