When rare diseases crisscross within the same patient: von Hippel-Lindau and type 1 gastric neuroendocrine tumor

Von-Hippel-Lindau (VHL) is a genetic multisystem disorder characterized by visceral cysts and benign and malignant tumors in various organs. Herein, we present the case of a 23-year-old woman with VHL presenting with multiple gastric neuroendocrine neoplasms (gNENs) type 1 in the context of chronic autoimmune gastritis (CAG). Although gNENs are not acknowledged as a typical entity in VHL patients, in the present case, gNENs were composed of neoplastic cells with clear cytoplasm usually seen in tumors related to VHL disease. We additionally performed a literature review on the presence of neuroendocrine clear cell tumors and report on further cases of clear cell NENs. The present case illustrates that clear-cell transformation in gNENs may be due to the dual genetic background of the patient; the real oncogenic stimulus may be more closely related to CAG than to VHL disease accompanied by an interplay between neoplastic and autoimmune processes. Therefore, close monitoring of patients with clear cell NENs appears to be important before excluding VHL disease, even in the context of phenotypically unrelated diseases.

Surgical Treatment of Solitary Metachronous Adrenal Metastasis from Urothelial Carcinoma of the Urinary Bladder

Urothelial cancer is a common neoplasm and metastatic disease correlates with a poor prognosis. Isolated adrenal gland metastases of urothelial carcinoma are quite rare, and management options can decide a patient's prognosis. Herein we report the case of a 76-year-old man with a metachronous solitary adrenal metastasis from a bladder carcinoma, who underwent adrenalectomy as part of his treatment. Furthermore, we discuss the cases of solitary adrenal metastases of urothelial carcinoma available in the literature, to identify key features to direct appropriate treatment of this rare metastatic site of urothelial cancer and improve prognosis and survival. Still, further prospective studies are needed to design effective therapeutic strategies.

Deoxyguanosine kinase mutation F180S is associated with a lean phenotype in mice

BACKGROUND

Deoxyguanosine kinase (DGUOK) deficiency is one of the genetic causes of mitochondrial DNA depletion syndrome (MDDS) in humans, leading to the hepatocerebral or the isolated hepatic form of MDDS. Mouse models are helpful tools for the improvement of understanding of the pathophysiology of diseases and offer the opportunity to examine new therapeutic options.

METHODS

Herein, we describe the generation and metabolic characterization of a mouse line carrying a homozygous Dguok^F180S/F180S mutation derived from an N-ethyl-N-nitrosourea-mutagenesis screen. Energy expenditure (EE), oxygen consumption (VO₂) and carbon dioxide production (VCO₂) were assessed in metabolic cages. LC-MS/MS was used to quantify plasma adrenal steroids. Plasma insulin and leptin levels were quantified with commercially available assay kits.

RESULTS

Mutant animals displayed significantly lower body weights and reduced inguinal fat pad mass, in comparison to unaffected littermates. Biochemically, they were characterized by significantly lower blood glucose levels, accompanied by significantly lower insulin, total cholesterol, high density lipoprotein and triglyceride levels. They also displayed an almost 2-fold increase in transaminases. Moreover, absolute EE was comparable in mutant and control mice, but EE in mutants was uncoupled from their body weights. Histological examination of inguinal white adipose tissue (WAT) revealed adipocytes with multilocular fat droplets reminiscent of WAT browning. In addition, mRNA and protein expression of Ucp1 was increased. Mutant mice also presented differing mitochondrial DNA content in various tissues and altered metabolic activity in mitochondria, but no further phenotypical or behavioral abnormalities. Preliminary data imply normal survival of Dguok^F180S/F180S mutant animals.

CONCLUSION

Taken together, DGUOK mutation F180S leads to a lean phenotype, with lower glucose, insulin, and lipid levels rendering this mouse model not only useful for the study of MDDS forms but also for deciphering mechanisms resulting in a lean phenotype.

The metabolic phenotype of patients with primary aldosteronism: impact of subtype and sex - a multicenter-study of 3566 Caucasian and Asian subjects

BACKGROUND

Accumulating evidence suggests that primary aldosteronism (PA) is associated with several features of the metabolic syndrome, in particular with obesity, type 2 diabetes mellitus, and dyslipidemia. Whether these manifestations are primarily linked to aldosterone-producing adenoma (APA) or bilateral idiopathic hyperaldosteronism (IHA) remains unclear. The aim of the present study was to investigate differences in metabolic parameters between APA and IHA patients and to assess the impact of treatment on these clinical characteristics.

METHODS

We conducted a retrospective multicenter study including 3566 patients with APA or IHA of Caucasian and Asian origin. We compared the prevalence of metabolic disorders between APA and IHA patients at the time of diagnosis and 1-year post-intervention, with special references to sex differences. Furthermore, correlations between metabolic parameters and plasma aldosterone, renin, or plasma cortisol levels after 1 mg dexamethasone (DST) were performed.

RESULTS

As expected, APA patients were characterized by higher plasma aldosterone and lower serum potassium levels. Only female IHA patients demonstrated significantly worse metabolic parameters than age-matched female APA patients, which were associated with lower cortisol levels upon DST. One-year post-intervention, female adrenalectomized patients showed deterioration of their lipid profile, when compared to patients treated with mineralocorticoid receptor antagonists. Plasma aldosterone levels negatively correlated with the BMI only in APA patients.

CONCLUSIONS

Metabolic alterations appear more prominent in women with IHA. Although IHA patients have worse metabolic profiles, a correlation with cortisol autonomy is documented only in APAs, suggesting an uncoupling of cortisol action from metabolic traits in IHA patients.

Age-dependent and sex-dependent disparity in mortality in patients with adrenal incidentalomas and autonomous cortisol secretion: an international, retrospective, cohort study

BACKGROUND

The association between cortisol secretion and mortality in patients with adrenal incidentalomas is controversial. We aimed to assess all-cause mortality, prevalence of comorbidities, and occurrence of cardiovascular events in uniformly stratified patients with adrenal incidentalomas and cortisol autonomy (defined as non-suppressible serum cortisol on dexamethasone suppression testing).

METHODS

We conducted an international, retrospective, cohort study (NAPACA Outcome) at 30 centres in 16 countries. Eligible patients were aged 18 years or older with an adrenal incidentaloma (diameter ≥1 cm) detected between Jan 1, 1996, and Dec 31, 2015, and availability of a 1 mg dexamethasone suppression test result from the time of the initial diagnosis. Patients with clinically apparent hormone excess, active malignancy, or follow-up of less than 36 months were excluded. Patients were stratified according to the 0800-0900 h serum cortisol values after an overnight 1 mg dexamethasone suppression test; less than 50 nmol/L was classed as non-functioning adenoma, 50-138 nmol/L as possible autonomous cortisol secretion, and greater than 138 nmol/L as autonomous cortisol secretion. The primary endpoint was all-cause mortality. Secondary endpoints were the prevalence of cardiometabolic comorbidities, cardiovascular events, and cause-specific mortality. The primary and secondary endpoints were assessed in all study participants.

FINDINGS

Of 4374 potentially eligible patients, 3656 (2089 [57·1%] with non-functioning adenoma, 1320 [36·1%] with possible autonomous cortisol secretion, and 247 [6·8%] with autonomous cortisol secretion) were included in the study cohort for mortality analysis (2350 [64·3%] women and 1306 [35·7%] men; median age 61 years [IQR 53-68]; median follow-up 7·0 years [IQR 4·7-10·2]). During follow-up, 352 (9·6%) patients died. All-cause mortality (adjusted for age, sex, comorbidities, and previous cardiovascular events) was significantly increased in patients with possible autonomous cortisol secretion (HR 1·52, 95% CI 1·19-1·94) and autonomous cortisol secretion (1·77, 1·20-2·62) compared with patients with non-functioning adenoma. In women younger than 65 years, autonomous cortisol secretion was associated with higher all-cause mortality than non-functioning adenoma (HR 4·39, 95% CI 1·93-9·96), although this was not observed in men. Cardiometabolic comorbidities were significantly less frequent with non-functioning adenoma than with possible autonomous cortisol secretion and autonomous cortisol secretion (hypertension occurred in 1186 [58·6%] of 2024 patients with non-functioning adenoma, 944 [74·0%] of 1275 with possible autonomous cortisol secretion, and 179 [75·2%] of 238 with autonomous cortisol secretion; dyslipidaemia occurred in 724 [36·2%] of 1999 patients, 547 [43·8%] of 1250, and 123 [51·9%] of 237; and any diabetes occurred in 365 [18·2%] of 2002, 288 [23·0%] of 1250, and 62 [26·7%] of 232; all p values <0·001).

INTERPRETATION

Cortisol autonomy is associated with increased all-cause mortality, particularly in women younger than 65 years. However, until results from randomised interventional trials are available, a conservative therapeutic approach seems to be justified in most patients with adrenal incidentaloma.

FUNDING

Deutsche Forschungsgemeinschaft, Associazione Italiana per la Ricerca sul Cancro, Università di Torino.

Changing biological behaviour of NETs during the evolution of the disease: progress on progression

Following improvements in the management and outcome of neuroendocrine neoplasms (NENs) in recent years, we see a subset, particularly of pancreatic NENs, which become more aggressive during the course of the disease. This is reflected by an increase in the Ki-67 labelling index, as a marker of proliferation, which may lead to an occasion of increase in grading, but generally does not appear to be correlated with histologically confirmed dedifferentiation. A systematic review of the literature was performed in PubMed, Cochrane Library, and Embase until May 2020 to identify cases that have behaved in such a manner. We screened 244 articles: only seven studies included cases in their cohort, or in a subset of the cohort studied, with a proven increase in the Ki-67 during follow-up through additional biopsy. In addition to these studies, we have also tried to identify possible pathophysiological mechanisms implicated in advanced NENs, although currently no studies appear to have addressed the mechanisms implicated in the switch to a more aggressive biological phenotype over the course of the disease. Such progression of the disease course may demand a change in the management. Summarising the overall evidence, we suggest that future studies should concentrate on changes in the molecular pathways during disease progression with sequential biopsies in order to shed light on the mechanisms that render a neoplasm more aggressive than its initial phenotype or genotype.

Clinical spectrum of primary adrenal lymphoma: results of a multicenter cohort study

Purpose

We sought to refine the clinical picture of primary adrenal lymphoma (PAL), a rare lymphoid malignancy with predominant adrenal manifestation and risk of adrenal insufficiency.

Methods

Ninety-seven patients from 14 centers in Europe, Canada and the United States were included in this retrospective analysis between 1994 and 2017.

Results

Of the 81 patients with imaging data, 19 (23%) had isolated adrenal involvement (iPAL), while 62 (77%) had additional extra-adrenal involvement (PAL+). Among patients who had both CT and PET scans, 18FDG-PET revealed extra-adrenal involvement not detected by CT scan in 9/18 cases (50%). The most common clinical manifestations were B symptoms (55%), fatigue (45%), and abdominal pain (35%). Endocrinological assessment was often inadequate. With a median follow-up of 41.6 months, 3-year progression-free (PFS) and overall (OS) survival rates in the entire cohort were 35.5% and 39.4%, respectively. The hazard ratios of iPAL for PFS and OS were 40.1 (95% CI: 2.63-613.7, P = 0.008) and 2.69 (95% CI: 0.61-11.89, P = 0.191), respectively. PFS was much shorter in iPAL vs PAL+ (median 4 months vs not reached, P = 0.006), and OS also appeared to be shorter (median 16 months vs not reached), but the difference did not reach statistical significance (P = 0.16). Isolated PAL was more frequent in females (OR = 3.81; P = 0.01) and less frequently associated with B symptoms (OR = 0.159; P = 0.004).

Conclusion

We found unexpected heterogeneity in the clinical spectrum of PAL. Further studies are needed to clarify whether clinical distinction between iPAL and PAL+ is corroborated by differences in molecular biology.

Urine steroid metabolomics for the differential diagnosis of adrenal incidentalomas in the EURINE-ACT study: a prospective test validation study

BACKGROUND

Cross-sectional imaging regularly results in incidental discovery of adrenal tumours, requiring exclusion of adrenocortical carcinoma (ACC). However, differentiation is hampered by poor specificity of imaging characteristics. We aimed to validate a urine steroid metabolomics approach, using steroid profiling as the diagnostic basis for ACC.

METHODS

We did a prospective multicentre study in adult participants (age ≥18 years) with newly diagnosed adrenal masses. We assessed the accuracy of diagnostic imaging strategies based on maximum tumour diameter (≥4 cm vs <4 cm), imaging characteristics (positive vs negative), and urine steroid metabolomics (low, medium, or high risk of ACC), separately and in combination, using a reference standard of histopathology and follow-up investigations. With respect to imaging characteristics, we also assessed the diagnostic utility of increasing the unenhanced CT tumour attenuation threshold from the recommended 10 Hounsfield units (HU) to 20 HU.

FINDINGS

Of 2169 participants recruited between Jan 17, 2011, and July 15, 2016, we included 2017 from 14 specialist centres in 11 countries in the final analysis. 98 (4·9%) had histopathologically or clinically and biochemically confirmed ACC. Tumours with diameters of 4 cm or larger were identified in 488 participants (24·2%), including 96 of the 98 with ACC (positive predictive value [PPV] 19·7%, 95% CI 16·2-23·5). For imaging characteristics, increasing the unenhanced CT tumour attenuation threshold to 20 HU from the recommended 10 HU increased specificity for ACC (80·0% [95% CI 77·9-82·0] vs 64·0% [61·4-66.4]) while maintaining sensitivity (99·0% [94·4-100·0] vs 100·0% [96·3-100·0]; PPV 19·7%, 16·3-23·5). A urine steroid metabolomics result indicating high risk of ACC had a PPV of 34·6% (95% CI 28·6-41·0). When the three tests were combined, in the order of tumour diameter, positive imaging characteristics, and urine steroid metabolomics, 106 (5·3%) participants had the result maximum tumour diameter of 4 cm or larger, positive imaging characteristics (with the 20 HU cutoff), and urine steroid metabolomics indicating high risk of ACC, for which the PPV was 76·4% (95% CI 67·2-84·1). 70 (3·5%) were classified as being at moderate risk of ACC and 1841 (91·3%) at low risk (negative predictive value 99·7%, 99·4-100·0).

INTERPRETATION

An unenhanced CT tumour attenuation cutoff of 20 HU should replace that of 10 HU for exclusion of ACC. A triple test strategy of tumour diameter, imaging characteristics, and urine steroid metabolomics improves detection of ACC, which could shorten time to surgery for patients with ACC and help to avoid unnecessary surgery in patients with benign tumours.

FUNDING

European Commission, UK Medical Research Council, Wellcome Trust, and UK National Institute for Health Research, US National Institutes of Health, the Claire Khan Trust Fund at University Hospitals Birmingham Charities, and the Mayo Clinic Foundation for Medical Education and Research.

Impact of 123 I-MIBG scintigraphy on clinical decision making in pheochromocytoma and paraganglioma

CONTEXT

Cross sectional imaging with computed tomography (CT) or magnetic resonance imaging (MRI) is regarded as a first-choice modality for tumor localization in patients with pheochromocytoma and paraganglioma (PPGL). 123I-labeled metaiodobenzylguanidine (123I-MIBG) is widely used for functional imaging but the added diagnostic value is controversial.

OBJECTIVE

To establish the virtual impact of adding 123I-MIBG scintigraphy to CT or MRI on diagnosis and treatment of PPGL.

DESIGN

International multicenter retrospective study.

INTERVENTION

None.

PATIENTS

236 unilateral adrenal, 18 bilateral adrenal, 48 unifocal extra-adrenal, 12 multifocal and 26 metastatic PPGL.

MAIN OUTCOME MEASURES

Patients underwent both anatomical imaging (CT and/or MRI) and 123I-MIBG scintigraphy. Local imaging reports were analyzed centrally by two independent observers who were blinded to the diagnosis. Imaging-based diagnoses determined by CT/MRI only, 123I-MIBG only, and CT/MRI combined with 123I-MIBG scintigraphy were compared with the correct diagnoses.

RESULTS

The rates of correct imaging-based diagnoses determined by CT/MRI only versus CT/MRI plus 123I-MIBG scintigraphy were similar: 89.4 versus 88.8%, respectively, (P=0.50). Adding 123I-MIBG scintigraphy to CT/MRI resulted in a correct change in the imaging-based diagnosis and ensuing virtual treatment in four cases (1.2%: two metastatic instead of non-metastatic, one multifocal instead of single, one unilateral instead of bilateral adrenal) at the cost of an incorrect change in seven cases (2.1%: four metastatic instead of non-metastatic, two multifocal instead of unifocal and one bilateral instead of unilateral adrenal).

CONCLUSIONS

For the initial localization of PPGL, the addition of 123I-MIBG scintigraphy to CT/MRI rarely improves the diagnostic accuracy at the cost of incorrect interpretation in others, even when 123I-MIBG scintigraphy is restricted to patients who are at risk for metastatic disease. In this setting, the impact of 123I-MIBG scintigraphy on clinical decision-making appears very limited.

Links between aldosterone excess and metabolic complications: A comprehensive review

Shortly after the first description of primary aldosteronism (PA) appeared in the 1950s by Jerome Conn, an association of the condition with diabetes mellitus was documented. However, a clear pathophysiological interrelationship linking the two entities has yet to be established. Nevertheless, so far, many mechanisms contributing to insulin resistance and dysregulation of glucose uptake have been described. At the same time, many observational studies have reported an increased prevalence of the metabolic syndrome (MetS) among patients with PA. Regarding the relationship between aldosterone levels and obesity, a vicious cycle of adipokine-induced aldosterone production and aldosterone adipogenic action may be further contributing to MetS manifestations in PA patients. However, whether aldosterone excess affects lipid metabolism is still under investigation. Also, recent findings of the coexistence of glucocorticoid excess in many cases of PA highlight the need for further studies to examine the presumed link between high aldosterone levels and various metabolic parameters. In the present review, our focus is to comprehensively present the spectrum of available research findings concerning the possible associations between aldosterone excess and metabolic alterations, including impaired glucose metabolism, insulin resistance and, consequently, diabetes, altered lipid metabolism and the development of fatty liver. In addition, the complex relationship between obesity and aldosterone is discussed in detail.

CT Characteristics of Pheochromocytoma: Relevance for the Evaluation of Adrenal Incidentaloma

Background

Up to 7% of all adrenal incidentalomas (AIs) are pheochromocytomas (PCCs). In the evaluation of AI, it is generally recommended that PCC be excluded by measurement of plasma-free or 24-hour urinary fractionated metanephrines. However, recent studies suggest that biochemical exclusion of PCC not be performed for lesions with CT characteristics of an adrenocortical adenoma (ACA).

Aim

To determine the proportion of PCCs with ACA-like attenuation or contrast washout on CT.

Methods

For this multicenter retrospective study, two central investigators independently analyzed the CT reports of 533 patients with 548 histologically confirmed PCCs. Data on tumor size, unenhanced Hounsfield units (HU), absolute percentage washout (APW), and relative percentage washout (RPW) were collected in addition to clinical parameters.

Results

Among the 376 PCCs for which unenhanced attenuation data were available, 374 had an attenuation of >10 HU (99.5%). In the two exceptions (0.5%), unenhanced attenuation was exactly 10 HU, which lies just within the range of ≤10 HU that would suggest a diagnosis of ACA. Of 76 PCCs with unenhanced HU > 10 and available washout data, 22 (28.9%) had a high APW and/or RPW, suggestive of ACA.

Conclusion

Based on the lack of PCCs with an unenhanced attenuation of <10 HU and the low proportion (0.5%) of PCCs with an attenuation of 10 HU, it seems reasonable to abstain from biochemical testing for PCC in AIs with an unenhanced attenuation of ≤10 HU. The assessment of contrast washout, however, is unreliable for ruling out PCC.

Mouse Models of Primary Aldosteronism: From Physiology to Pathophysiology

Primary aldosteronism (PA) is a common form of endocrine hypertension that is characterized by the excessive production of aldosterone relative to suppressed plasma renin levels. PA is usually caused by either a unilateral aldosterone-producing adenoma or bilateral adrenal hyperplasia. Somatic mutations have been identified in several genes that encode ion pumps and channels that may explain the aldosterone excess in over half of aldosterone-producing adenomas, whereas the pathophysiology of bilateral adrenal hyperplasia is largely unknown. A number of mouse models of hyperaldosteronism have been described that recreate some features of the human disorder, although none replicate the genetic basis of human PA. Animal models that reproduce the genotype-phenotype associations of human PA are required to establish the functional mechanisms that underlie the endocrine autonomy and deregulated cell growth of the affected adrenal and for preclinical studies of novel therapeutics. Herein, we discuss the differences in adrenal physiology across species and describe the genetically modified mouse models of PA that have been developed to date.

Changes in Body Mass Index in Pheochromocytoma Patients Following Adrenalectomy

Catecholamine excess from pheochromocytoma results in cardiovascular symptoms such as arterial hypertension and tachycardia and induces metabolic alterations including glucose intolerance and increase in resting metabolic rate. The objective of our study was to investigate the effect of surgical cure of pheochromocytoma on body-mass-index and the correlation of body-mass-index changes to preoperative endocrine parameters. Pheochromocytoma patients from the Munich ENSAT Registry were matched (1:2) for age and gender to patients from the German Conn's Registry, who had undergone surgery for aldosterone-producing-adenomas. Thereby, 43 pheochromocytoma patients (17 males/26 females) and 86 aldosterone-producing-adenoma patients were analyzed for body-mass-index, blood pressure, and catecholamine levels before and one year after adrenalectomy. Seventy-four percent of pheochromocytoma patients were hypertensive preoperatively and 48% one year postoperatively. Systolic blood pressure did not differ significantly in pre- and postoperative measurements whereas diastolic blood pressure was significantly reduced over time. Moreover, pheochromocytoma patients gained body weight (p<0.001) one year following adrenalectomy accompanied by significant increases in body-mass-index, whereas aldosterone-producing adenoma patients displayed a slight weight loss. Despite weight gain, diagnosis of diabetes mellitus dropped from 9 of 43 investigated pheochromocytoma patients at baseline to 4 at follow-up. A significant correlation between body-mass-index changes to the preoperative catecholamine levels was found only for urinary normetanephrines. These data suggest that normalization of chronic catecholamine excess by adrenalectomy is associated with an increase in body-mass-index, which is more pronounced in patients with high preoperative levels of urinary normetanephrines.

Genetic characterization of a mouse line with primary aldosteronism

In an attempt to define novel genetic loci involved in the pathophysiology of primary aldosteronism, a mutagenesis screen after treatment with the alkylating agent N-ethyl-N-nitrosourea was established for the parameter aldosterone. One of the generated mouse lines with hyperaldosteronism was phenotypically and genetically characterized. This mouse line had high aldosterone levels but normal creatinine and urea values. The steroidogenic enzyme expression levels in the adrenal gland did not differ significantly among phenotypically affected and unaffected mice. Upon exome sequencing, point mutations were identified in seven candidate genes (Sspo, Dguok, Hoxaas2, Clstn3, Atm, Tipin and Mapk6). Subsequently, animals were stratified into wild-type and mutated groups according to their genotype for each of these candidate genes. A correlation of their genotypes with the respective aldosterone, aldosterone-to-renin ratio (ARR), urea and creatinine values as well as steroidogenic enzyme expression levels was performed. Aldosterone values were significantly higher in animals carrying mutations in four different genes (Sspo, Dguok, Hoxaas2 and Clstn3) and associated statistically significant adrenal Cyp11b2 overexpression as well as increased ARR was present only in mice with Sspo mutation. In contrast, mutations of the remaining candidate genes (Atm, Tipin and Mapk6) were associated with lower aldosterone values and lower Hsd3b6 expression levels. In summary, these data demonstrate association between the genes Sspo, Dguok, Hoxaas2 and Clstn3 and hyperaldosteronism. Final proofs for the causative nature of the mutations have to come from knock-out and knock-in experiments.

Adrenal and Ovarian Phenotype of a Tissue-Specific Urocortin 2-Overexpressing Mouse Model

Urocortin 2 (UCN2) is a neuropeptide of the CRH family, involved in homeostatic mechanisms, the stress response, and control of anxiety. To elucidate the effects of UCN2 on steroidogenesis, we developed a mouse model that allows a Cre recombinase-determined conditional overexpression of UCN2 (UCN2-COE). In these mice SF1-Cre-driven overexpression of UCN2 was restricted to the adrenal glands, gonads, and parts of the hypothalamus. UCN2-COE animals of both sexes revealed significantly higher plasma UCN2 levels and significantly higher UCN2 expression levels in the adrenals and ovaries. In contrast, the baseline expression of UCN2 was already high in the testes of control mice with no further increase achievable in UCN2-COE animals. Adrenal steroidogenesis of UCN2-COE animals was investigated under baseline conditions, upon an ACTH stimulation test, and following a restraint stress test. A tendency toward lower expression of steroidogenic enzymes was detectable in UCN2-COE animals of both sexes with slight differences between males and females. A similar reduction in the expression levels of the final steps of ovarian steroidogenesis, accompanied by reduced plasma estradiol levels, was observed in female UCN2-COE animals. Thus, adrenal UCN2 overexpression resulted in down-regulation of adrenal steroidogenesis, suggesting a reduction in the stress response in the mouse (stress coping behavior). Similarly, UCN2 overexpression in the ovaries caused a decrease in steroidogenesis and reduction of follicles that had undergone ovulation. Nevertheless, this finding was not associated with reduced fertility.

Diastrophic dysplasia sulfate transporter (SLC26A2) is expressed in the adrenal cortex and regulates aldosterone secretion

Elucidation of the molecular mechanisms leading to autonomous aldosterone secretion is a prerequisite to define potential targets and biomarkers in the context of primary aldosteronism. After a genome-wide association study with subjects from the population-based Cooperative Health Research in the Region of Augsburg F4 survey, we observed a highly significant association (P=6.78×10(-11)) between the aldosterone to renin ratio and a locus at 5q32. Hypothesizing that this locus may contain genes of relevance for the pathogenesis of primary aldosteronism, we investigated solute carrier family 26 member 2 (SLC26A2), a protein with known transport activity for sulfate and other cations. Within murine tissues, adrenal glands showed the highest expression levels for SLC26A2, which was significantly downregulated on in vivo stimulation with angiotensin II and potassium. SLC26A2 expression was found to be significantly lower in aldosterone-producing adenomas in comparison with normal adrenal glands. In adrenocortical NCI-H295R cells, specific knockdown of SLC26A2 resulted in a highly significant increase in aldosterone secretion. Concomitantly, expression of steroidogenic enzymes, as well as upstream effectors including transcription factors such as NR4A1, CAMK1, and intracellular Ca(2+) content, was upregulated in knockdown cells. To substantiate further these findings in an SLC26A2 mutant mouse model, aldosterone output proved to be increased in a sex-specific manner. In summary, these findings point toward a possible effect of SLC26A2 in the regulation of aldosterone secretion potentially involved in the pathogenesis of primary aldosteronism.

Gender-, strain-, and inheritance-dependent variation in aldosterone secretion in mice

Arterial hypertension represents one of the most common diseases in developed countries and the rennin-angiotensin-aldosterone system is among the major factors in the regulation of blood pressure and sodium balance. With the exception of rare monogenetic diseases, however, inheritance of aldosterone secretion is widely unknown. In this study, we investigated the aldosterone levels in male and female mice of two inbred strains, C3HeB/FeJ and C57BL/6J, as well as their offspring of the F1 and F2 generation. In all cases, female animals displayed lower aldosterone levels than males. Furthermore, C57BL/6J animals had significantly higher aldosterone levels than C3HeB/FeJ mice of the same age and gender. Depending on the paternal origin of the animal, the F1 offspring showed a tendency toward higher aldosterone values when the paternal side was from the C57BL/6J strain. This observation was confirmed in the F2 generation and over repeated measurements over three consecutive years. Quantification of the aldosterone to renin ratio in the different mouse groups did not show any significant differences, and, similarly, the determination of plasma potassium and kidney parameters did not provide any differences. On the molecular level, investigation of the expression of the enzymes involved in steroidogenesis displayed the same trend as for the aldosterone values, with animals hosting C57BL/6J background in their paternal origin having also the highest expression levels for StAR, cyp11a1, and cyp11b2 enzymes. Taken together, we could demonstrate that the genetic background of the animals plays a significant role modulating their plasma aldosterone levels without clear interference of other parameters in the renin-angiotensin-aldosterone system.

Screening for primary aldosteronism in hypertensive subjects: results from two German epidemiological studies

OBJECTIVE

The prevalence of primary aldosteronism in unselected hypertensive patients is currently unknown. We investigated the frequency of positive screening results for primary aldosteronism based on the aldosterone-to-renin ratio (ARR) in hypertensive subjects aged 30-79 years from two German epidemiological studies. We further examined the frequency of positive screening results in subjects with resistant hypertension or stage III hypertension and assessed possible disparities between untreated and treated hypertensive subjects.

METHODS

Data were obtained from the first follow-ups of the population-based study of health in Pomerania (SHIP; n=1392) and the cooperative health research in the region of Augsburg (KORA; n=1052). Study-specific reference ranges for plasma aldosterone concentration (PAC), plasma renin concentration (PRC) and the ARR were applied. Confirmation tests for primary aldosteronism were not performed in these epidemiological studies.Three definitions for a positive screening for primary aldosteronism were applied: A) increased ARR; B) increased ARR and decreased PRC; and C) increased ARR and increased PAC and decreased PRC.

RESULTS

The frequency of positive screening results was 7.0, 3.8 and 0.2% according to definitions A-C respectively. In the subgroups of subjects with resistant hypertension (11.9, 5.5 and 0.9%) or stage III hypertension (18.3, 14.0 and 1.1%), these frequencies were markedly higher than those in the general hypertensive population. There was no difference in the frequency of positive screening results between the treated and untreated hypertensive subjects.

CONCLUSIONS

A maximum of 7.0% of the hypertensive population in Germany shows a positive screening result for primary aldosteronism. Thus, primary aldosteronism may be less frequent than previously expected based on data from referred hypertensive patients.

Urocortin-dependent effects on adrenal morphology, growth, and expression of steroidogenic enzymes in vivo

Urocortin (UCN) 1, 2, and 3 are members of the corticotropin-releasing factor (CRF) family that display varying affinities to the CRF receptor 1 (CRFR1 (CRHR1)) and 2 (CRFR2 (CRHR2)). UCNs represent important modulators of stress responses and are involved in the control of anxiety and related disorders. In addition to the CNS, UCNs and CRFRs are highly expressed in several tissues including the adrenal gland, indicating the presence of UCN-dependent regulatory mechanisms in these peripheral organ systems. Using knockout (KO) mouse models lacking single or multiple Ucn genes, we examined the potential role of the three different Ucns on morphology and function of the adrenal gland. Adrenal morphology was investigated, organ size, cell size, and number were quantified, and growth kinetics were studied by proliferative cell nuclear antigen staining and Ccnd1 expression analysis. Furthermore, mRNA expression of enzymes involved in steroidogenesis and catecholamine synthesis was quantified by real-time PCR. Following this approach, Ucn2, Ucn1/Ucn2 dKO and Ucn1/Ucn2/Ucn3 tKO animals showed a significant cellular hypotrophy of the adrenal cortex and an increase in Ccnd1 expression, whereas in all other genotypes, no changes were observable in comparison to age-matched controls. For steroidogenesis, Ucn2/Ucn3 dKO animals displayed the most pronounced changes, with significant increases in all investigated enzymes, providing indirect evidence for increased stress behavior. Taken together, these data suggest that mainly Ucn2 and Ucn3 could be involved in adrenal stress response regulation while Ucn2 additionally appears to play a role in morphology and growth of the adrenal gland.

ACTH-dependent regulation of microRNA as endogenous modulators of glucocorticoid receptor expression in the adrenal gland

MicroRNA (miR) are a subset of small RNA molecules, which posttranscriptionally modulate target gene expression. Although miR have been demonstrated to impact a number of processes during development and tumorigenesis, little is known about the expression and the role of miR in the adrenal gland. Because tight regulation of steroid synthesis is crucial for maintaining homeostasis upon stressful stimuli, here, we determined the miR expression pattern in mouse adrenal glands under baseline conditions, as well as 10, 30, and 60 min upon ACTH stimulation, using miR microarray. Changes in miR expression levels detected by array analysis were confirmed by real-time PCR and further analyzed by bioinformatic tools to identify miR that putatively target genes involved in adrenal function. After selecting miR, with a significant change in their expression level upon ACTH stimulation, four of the predefined miR (miR-96, miR-101a, miR-142-3p, and miR-433) were found to putatively target the glucocorticoid receptor [nuclear receptor subfamily 3, group C, member 1 (Nr3c1)]. Nr3c1 expression levels were elevated 10 min after ACTH stimulation but decreased after 60 min in comparison with baseline conditions. Modified Nr3c1-3'-untranslated region constructs were further tested by in vitro luciferase assays. Thereby, we could confirm that miR96, miR101a, miR142-3p, and miR433 target the Nr3c1-3'-untranslated region and result in a 20-40% repression of it. Taken together, ACTH stimulation could be demonstrated to acutely influence adrenal miR expression pattern in vivo; thus, potentially modulating adrenal response to acute stressors.

Primary adrenal lymphoma: 3 case reports with different outcomes

Primary adrenal lymphoma (PAL) is an extremely rare entity, with approximately 70 cases reported in the English literature and 120 cases worldwide. Here we report the cases of a 53-year-old and a 62-year-old male patient and a 60-year-old female patient affected by large B-cell non-Hodgkin lymphoma of the adrenal gland. We summarize the diagnostic approaches that confirmed the diagnosis of PAL and describe individual treatment outcomes after therapy. Based on these case reports and a review of the literature patients are usually in the 6th or 7th decade of life and present with B-symptoms or rapidly progressive adrenal insufficiency in case of bilateral involvement. The identification of bilateral adrenal masses often causes a severe diagnostic problem. An etiological approach with assessment of the hormonal profile and detailed diagnostic imaging should be aimed at. Furthermore, if PAL is suspected biopsy of the adrenal mass should be performed after biochemical exclusion of a pheochromocytoma. Once the diagnosis is established further treatment decisions should be made in a multi-disciplinary setting in specialized centers.

A genome-wide association study identifies novel loci associated with circulating IGF-I and IGFBP-3

Insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-3 (IGFBP-3) are involved in cell replication, proliferation, differentiation, protein synthesis, carbohydrate homeostasis and bone metabolism. Circulating IGF-I and IGFBP-3 concentrations predict anthropometric traits and risk of cancer and cardiovascular disease. In a genome-wide association study of 10 280 middle-aged and older men and women from four community-based cohort studies, we confirmed a known association of single nucleotide polymorphisms in the IGFBP3 gene region on chromosome 7p12.3 with IGFBP-3 concentrations using a significance threshold of P < 5 × 10(-8) (P = 3.3 × 10(-101)). Furthermore, the same IGFBP3 gene locus (e.g. rs11977526) that was associated with IGFBP-3 concentrations was also associated with the opposite direction of effect, with IGF-I concentration after adjustment for IGFBP-3 concentration (P = 1.9 × 10(-26)). A novel and independent locus on chromosome 7p12.3 (rs700752) had genome-wide significant associations with higher IGFBP-3 (P = 4.4 × 10(-21)) and higher IGF-I (P = 4.9 × 10(-9)) concentrations; when the two measurements were adjusted for one another, the IGF-I association was attenuated but the IGFBP-3 association was not. Two additional loci demonstrated genome-wide significant associations with IGFBP-3 concentration (rs1065656, chromosome 16p13.3, P = 1.2 × 10(-11), IGFALS, a confirmatory finding; and rs4234798, chromosome 4p16.1, P = 4.5 × 10(-10), SORCS2, a novel finding). Together, the four genome-wide significant loci explained 6.5% of the population variation in IGFBP-3 concentration. Furthermore, we observed a borderline statistically significant association between IGF-I concentration and FOXO3 (rs2153960, chromosome 6q21, P = 5.1 × 10(-7)), a locus associated with longevity. These genetic loci deserve further investigation to elucidate the biological basis for the observed associations and clarify their possible role in IGF-mediated regulation of cell growth and metabolism.

Utilization of a mutagenesis screen to generate mouse models of hyperaldosteronism

Primary aldosteronism is considered to be responsible for almost 10% of all cases of arterial hypertension. The genetic background of this common disease, however, has been elucidated only for the rare familial types, whereas in the large majority of sporadic cases, underlying mechanisms still remain unclear. In an attempt to define novel genetic loci involved in the pathophysiology of primary aldosteronism, a mutagenesis screen after treatment of mice with the alkylating agent N-ethyl-N-nitrosourea was established for the parameter aldosterone. As the detection method we used a time-resolved fluorescence immunoassay that allows the measurement of aldosterone in very small murine sample volumes. Based on this assay, we first determined the normal aldosterone values for wild-type C3HeB/FeJ mice under baseline conditions [92 ± 6 pg/ml for females (n = 69) and 173 ± 16 pg/ml for males (n = 55)]. Subsequently, aldosterone measurement was carried out in more than 2800 F(1) offspring of chemically mutagenized C3HeB/FeJ mice, and values were compared with aldosterone levels from untreated animals. Persistent hyperaldosteronism (defined as levels +3 sd above the mean of untreated animals) upon repeated measurements was present in seven female and two male F(1) offspring. Further breeding of these founders gave rise to F(2) pedigrees from which eight lines with different patterns of inheritance of hyperaldosteronism could be established. These animals will serve for detailed phenotypic and genetic characterization in the future. Taken together, our data demonstrate the feasibility of a phenotype-driven mutagenesis screen to detect and establish mutant mouse lines with a phenotype of chronic hyperaldosteronism.

A microsphere-based duplex competitive immunoassay for the simultaneous measurements of aldosterone and testosterone in small sample volumes: validation in human and mouse plasma

BACKGROUND

The small blood volumes available in rodent studies often limit adequate quantification of all hormones of interest. We report here the development of two new assays combining an extraction step with multiplex immunoassay (MIA) technology for the simultaneous determination of aldosterone and testosterone in 50 μl sample volume.

METHODS

Following solvent extraction, aldosterone and testosterone competitive immunoassays are performed incorporating biotinylated tracers and antibody-coated beads each having a unique fluorescence. Quantification is via addition of streptavidin-R-phycoerythrin (SA-PE). The assays were validated and compared to established methods. Baseline hormone levels in mice from four different strains, and changes after ACTH and HCG stimulation in CD-1 mice are shown.

RESULTS

The assays are sensitive (aldosterone 15 pg/ml, testosterone 12 pg/ml), reproducible (intra-/inter-assay imprecision aldosterone 5.1-15.6%/9.9-15.8% and testosterone 9.7-10.9%/7.7-11.4%) and correlate significantly to established assays (r=0.94-0.95). Baseline aldosterone levels varied between strains, but not between the genders. Testosterone was significantly higher in male of all strains except in C57BL/6 × NMRI mice. After ACTH injection, aldosterone (median, interquartile range) rose from 354 (261-396) pg/ml to 2008 (875-2467) in male and from 260 (210-576) to 1120 (734-1528) in female CD-1 mice. HCG injection in the same strain increased testosterone in male mice only (3.5 (0.4-8.3) ng/ml to 31.8 (30.4-33.9) ng/ml, P<0.01).

CONCLUSIONS

We describe a MIA for the simultaneous measurement of aldosterone and testosterone in small volumes after extraction. In addition to presenting a new tool for steroid research in rodent models, our data show strain-dependent differences in steroid hormone metabolism in rodents.

Identification of adrenal genes regulated in a potassium-dependent manner

Potassium and angiotensin II are the main stimulators of aldosterone secretion from the adrenal cortex. As potassium-induced in vivo gene regulation in the adrenal cortex has not been studied in detail, we applied a stepwise screening approach: first, we investigated the effects of chronic potassium substitution in mice. Microarray analysis of adrenal glands revealed a set of genes (set A) that were counter-regulated in a high potassium (HP) and low potassium substitution group, while others (set B) were highly upregulated in the HP intake group. In a second step, time dependency of expression changes of these pre-defined genes was studied following short-term potassium stimulation experiments in vivo. Thirdly, dose dependency of potassium-induced gene regulation was investigated in vitro. Finally, to provide indirect evidence for the potential relevance of the detected changes for autonomous aldosterone secretion, expression analysis of aldosterone-producing adenomas was compared with normal adrenal glands. While most investigated genes were similarly regulated following long- and short-term potassium stimulation in vivo, observed changes were reproducible in NCI h295R adrenocortical cells mostly for the set of genes identified in the HP group (set B). Similarly, in Conn's adenomas, mostly genes from set B displayed changes in expression pattern in comparison to normal adrenal glands, while genes from set A were mostly unchanged. Thus, while in vivo models can help in identifying genes potentially involved in potassium-dependent aldosterone secretion, these findings also underline the necessity to interpret potassium-induced gene regulation on the basis of the experimental setting.

Saliva as a medium for aldosterone measurement in repeated sampling studies

BACKGROUND

Saliva is a readily available biological fluid, making it convenient in diagnosis of diseases and in multi-sampling protocols. Several salivary steroids give a useful index of free plasma levels. Increased incidence of primary aldosteronism (PA) in approximately 10% of the hypertensive population has increased interest in the mineralocorticoid aldosterone.

METHODS

A biotinylated-aldosterone tracer and a commercially available antibody are used in a time-resolved fluorescence immunoassay (TR-FIA) to measure salivary aldosterone (SA). Saliva was collected in various multi-sampling protocols: Investigation of diurnal rhythm in healthy and PA patients, ACTH stimulation test and posture test in healthy subjects.

RESULTS

Method validation showed a sensitivity of 19 ng/L and intra-/inter-assay precision between 7.2-10.1% and 8.7-15.7%, respectively. SA correlated significantly (y = 0.2995x +/- 0.01, r(2)=0.60) to plasma aldosterone measured by a commercial radioimmunoassay. SA (median; 95%CI) was at 111 (95-127)ng/L in PA (n=84) and 50 (44-56)ng/L in healthy subjects (n=60). After change in posture, aldosterone increased in both, saliva (57 (47-63)ng/L to 95 (84-117)ng/L) and plasma (26 (26-41)ng/L to 135 (110-181)ng/L). Peak levels were reached after 1h, and were higher in females than in males.

CONCLUSIONS

SA correlates well to plasma aldosterone and mirrors responses during conditions of stress. SA is significantly higher in PA, and the diurnal rhythm seen in the healthy is blunted in PA. We additionally found gender-dependent differential responses to posture, with higher increases in females. Measurement of aldosterone in saliva presents a useful and convenient method for application in multi-sampling studies.

Short term regulation of aldosterone secretion after stimulation and suppression experiments in mice

Aldosterone is synthesized acutely from the zona glomerulosa cells upon stimulation by the renin-angiotensin-aldosterone system. Several enzymes are involved in this steroidogenic process including the steroidogenic acute regulatory protein (StAR), P450 side chain cleavage enzyme (Cyp11a1), and aldosterone synthase (Cyp11b2) which has been demonstrated to be transcriptionally regulated by the nuclear transcription factors NGF1-B and Nurr1. We investigated the short time transcriptional regulation of these genes in wild-type mice at 10 min intervals for 1 h following application of 0.2 nmol angiotensin II (ANGII) or sodium chloride in comparison sham injections. Using real-time PCR a fast upregulation of adrenal Cyp11b2 expression (53+/-5% increase over baseline) could be observed 10 min after sham injection which was accompanied by a transient increase in aldosterone secretion while StAR and Cyp11a1 upregulation was delayed and more sustained. ANGII caused an increase of StAR and Cyp11a1 expression similar to that observed after sham injection while Cyp11b2 upregulation was more pronounced (10 min, 236+/-39%) and reflected ANGII induced stimulation of aldosterone output. Sodium challenge was followed by a sustained reduction of all three genes examined (Cyp11b2, 20 min, -63+/-6%) which was accompanied by a significant suppression of aldosterone secretion detectable after 60 min. While increases in NGF1-B mRNA levels were similar between the treatment groups, Nurr1 expression levels were induced only upon ANGII administration. These data suggest that acute regulation of aldosterone synthesis is accompanied by fast transcriptional modulation of steroidogenic enzymes and transcription factors that are likely to be involved in aldosterone secretion.