Kinetics of Intermediate Release Enhances P450 11B2-Catalyzed Aldosterone Synthesis.

The mitochondrial enzyme cytochrome P450 11B2 (aldosterone synthase) catalyzes the 3 terminal transformations in the biosynthesis of aldosterone from 11-deoxycorticosterone (DOC): 11ß-hydroxylation to corticosterone, 18-hydroxylation, and 18-oxidation. Prior studies have shown that P450 11B2 produces more aldosterone from DOC than from the intermediate corticosterone and that the reaction sequence is processive, with intermediates remaining bound to the active site between oxygenation reactions. In contrast, P450 11B1 (11ß-hydroxylase), which catalyzes the terminal step in cortisol biosynthesis, shares a 93% amino acid sequence identity with P450 11B2, converts DOC to corticosterone, but cannot synthesize aldosterone from DOC. The biochemical and biophysical properties of P450 11B2, which enable its unique 18-oxygenation activity and processivity, yet are not also represented in P450 11B1, remain unknown. To understand the mechanism of aldosterone biosynthesis, we introduced point mutations at residue 320, which partially exchange the activities of P450 11B1 and P450 11B2 (V320A and A320V, respectively). We then investigated NADPH coupling efficiencies, binding kinetics and affinities, and product formation of purified P450 11B1 and P450 11B2, wild-type, and residue 320 mutations in phospholipid vesicles and nanodiscs. Coupling efficiencies for the 18-hydroxylase reaction with corticosterone as the substrate failed to correlate with aldosterone synthesis, ruling out uncoupling as a relevant mechanism. Conversely, corticosterone dissociation rates correlated inversely with aldosterone production. We conclude that intermediate dissociation kinetics, not coupling efficiency, enable P450 11B2 to synthesize aldosterone via a processive mechanism. Our kinetic data also suggest that the binding of DOC to P450 11B enzymes occurs in at least two distinct steps, favoring an induced-fit mechanism.

The Spectrum of Dysregulated Aldosterone Production: An International Human Physiology Study.

CONTEXT: Primary aldosteronism is a form of low-renin hypertension characterized by dysregulated aldosterone production. OBJECTIVE: To investigate the contributions of renin-independent aldosteronism, and ACTH-mediated aldosteronism, in individuals with a low-renin phenotype representing the entire continuum of blood pressure. . DESIGN/PARTICIPANTS: Human physiology study of 348 participants with a low-renin phenotype with severe and/or resistant hypertension, hypertension with hypokalemia, elevated blood pressure and stage I/II hypertension, and normal blood pressure. SETTING: 4 international centers. . INTERVENTIONS/MAIN OUTCOME MEASURES: Saline suppression test (SST) to quantify the magnitude of renin-independent aldosteronism; dexamethasone suppression and ACTH-stimulation tests to quantify the magnitude of ACTH-mediated aldosteronism; adrenal venous sampling to determine lateralization. RESULTS: There was a continuum of non-suppressible and renin-independent aldosterone production following SST that paralleled the magnitude of the blood pressure continuum and transcended conventional diagnostic thresholds. In parallel, there was a full continuum of ACTH-mediated aldosteronism wherein post-SST aldosterone levels were strongly correlated with ACTH-stimulated aldosterone production (r = 0.75, P < 0.0001) and non-suppressible aldosterone production post-dexamethasone (r = 0.40, P < 0.0001). Beyond participants who met criteria for primary aldosteronism (post-SST aldosterone of ≥10 ng/dL or ≥277 pmol/L), the continuum of non-suppressible and renin-independent aldosterone production persisted below this diagnostic threshold, wherein 15% still had lateralizing aldosteronism amenable to surgical adrenalectomy, and the remainder were treated with mineralocorticoid receptor antagonists. CONCLUSIONS: In the context of a low-renin phenotype, there is a continuum of dysregulated aldosterone production that is prominently influenced by ACTH. A large proportion of individuals with low-renin have dysregulated aldosterone production and may benefit from aldosterone-directed therapy.

Severe aldosterone synthase deficiency in a nine-day old Lebanese boy: the importance of functional studies to establish pathogenicity of seemingly benign variants in CYP11B2.

Introduction Aldosterone synthase deficiency is a rare autosomal recessive disease characterized by vomiting, dehydration, salt wasting, life-threatening hyperkalemia in infancy, followed by failure to thrive. It results from pathogenic variants in CYP11B2. Case Presentation A boy, born in Montreal to Lebanese parents who are first cousins, was referred at nine days of life for severe dehydration. A diagnosis of primary adrenal insufficiency was made, and treatment was started with fludrocortisone and hydrocortisone. Exome sequencing revealed a homozygous variant p.(Asn201Asp)(N201D). In silico, this variant was considered benign, but in vitro functional expression studies established it caused the severe aldosterone deficiency. It ended the diagnostic odyssey and allowed to safely stop hydrocortisone replacement. Conclusion If a gene variant co-segregates with a phenotype, in vitro functional studies are required even if in silico studies are negative.

A Contemporary Approach to the Diagnosis and Management of Adrenal Insufficiency.

Adrenal insufficiency (AI) can be classified into three distinct categories based on its underlying causes: primary adrenal disorders, secondary deficiencies in adrenocorticotropin, or hypothalamic suppression from external factors, most commonly glucocorticoid medications used for anti-inflammatory therapy. The hallmark clinical features of AI include fatigue, appetite loss, unintentional weight loss, low blood pressure, and hyponatremia. Individuals with primary AI additionally manifest skin hyperpigmentation, hyperkalemia, and salt craving. The diagnosis of AI is frequently delayed due to the non-specific symptoms and signs early in the disease course, which poses a significant challenge to its early detection prior to an adrenal crisis. Despite the widespread availability of lifesaving glucocorticoid medications for decades, notable challenges persist, particularly in the domains of timely diagnosis while simultaneously avoiding misdiagnosis, patient education for averting adrenal crises, and the determination of optimal replacement therapies. This article reviews recent advancements in the contemporary diagnostic strategy and approaches to optimal treatment for AI.

Prospective early adulthood risk factors for vasomotor symptoms in the Coronary Artery Risk Development in Young Adults study.

OBJECTIVE: Previous studies have assessed potential risk factors for vasomotor symptoms (VMS) beginning in midlife. We examined whether early adulthood risk factors predict VMS trajectories over time. METHODS: We performed a secondary data analysis of the Coronary Artery Risk Development in Young Adults (CARDIA) study, a population-based cohort. We included women who answered questions about VMS at three or more examinations (n = 1,966). We examined whether risk factors at baseline (when participants were aged 18-30 y; average age, 25 y) and the year 15 (Y15) exam (at ages 33-45 y; average age, 40 y) were associated with VMS trajectories from Y15 through Y35. Logistic regression models were used to evaluate the associations with VMS trajectories. RESULTS: We identified three trajectories of VMS presence: minimal (40%), increasing over time (27%), and persistent (33%). Baseline factors associated with persistent VMS over time included Black race, less than a high school education, depressive symptoms, migraines, cigarette use, and at Y15 hysterectomy. Baseline factors associated with increasing VMS over time included Black race and lower body mass index. Risk factors for bothersome VMS were similar and also included thyroid disease, although thyroid disease was not associated with persistence of VMS over time. Associations were similar among women who had not undergone hysterectomy and in Black and White women. CONCLUSIONS: Risk factors for VMS may be identified in early adulthood. Further examination of risk factors such as migraines and depressive symptoms in early adulthood may be helpful in identifying therapies for VMS.

Predictors of Cardiovascular Morbidities in Adults With 21-Hydroxylase Deficiency Congenital Adrenal Hyperplasia.

CONTEXT: The prevalence of cardiovascular and metabolic complications among adults with 21-hydroxylase deficiency (21OHD) is unknown. OBJECTIVE: We sought to determine the prevalence of cardiovascular and metabolic morbidities among adults with 21OHD and to identify clinical factors and biomarkers associated with cardiovascular outcomes. METHODS: A 10-year retrospective cross-sectional analysis was conducted on adult patients with confirmed 21OHD, aged 18 to 70 years, who had at least one clinical visit for assessment at the University of Michigan. The presence of cardiovascular diseases (CVDs) and other metabolic comorbidities was extracted from medical records based on International Classification of Diseases (ICD) codes. Medical treatments, glucocorticoid (GC) and mineralocorticoid doses, as well as specific biomarkers of disease control since age 18, were collected for analysis. RESULTS: A total of 254 patients with 21OHD, median age of 35 years (interquartile range, 28.25-46 y), were included in the analysis. The prevalence of CVDs in the entire cohort was 7.5%. An increase in prevalence was seen from early adulthood, reaching 25% in patients older than 60 years. Increasing age (adjusted odds ratio [OR], 1.05; 95% CI, 1.01-1.09), hypertension (OR, 4.27; 95% CI, 1.41-12.92), and higher GC doses (OR, 1.51; 95% CI, 1.11-2.06) were significantly associated with prevalent CVDs. Higher plasma renin activity was significantly associated with CVDs (OR, 1.07; 95% CI, 1.01-1.15) but not other biochemical markers of disease. CONCLUSION: Cardiometabolic morbidities are prevalent among adults with 21OHD. Hypertension, age, and GC exposure are the main predictive factors of established CVDs in our cohort.

Therapeutic management of congenital forms of endocrine hypertension.

Congenital forms of endocrine hypertension are rare and potentially life-threatening disorders, primarily caused by genetic defects affecting adrenal steroid synthesis and activation pathways. These conditions exhibit diverse clinical manifestations, which can be distinguished by their unique molecular mechanisms and steroid profiles. Timely diagnosis and customized management approach are crucial to mitigate unfavorable outcomes associated with uncontrolled hypertension and other related conditions. Treatment options for these disorders depend on the distinct underlying pathophysiology, which involves specific pharmacological therapies or surgical adrenalectomy in some instances. This review article summarizes the current state of knowledge on the therapeutic management of congenital forms of endocrine hypertension, focusing on familial hyperaldosteronism (FH), congenital adrenal hyperplasia, apparent mineralocorticoid excess, and Liddle syndrome. We provide an overview of the genetic and molecular pathogenesis underlying each disorder, describe the clinical features, and discuss the various therapeutic approaches available and their risk of adverse effects, aiming to improve outcomes in patients with these rare and complex conditions.

Bacterial expression, purification, and reconstitution of human steroid 5α-reductases in phospholipid liposomes and nanodiscs.

The two human steroid 5α-reductase (5αR) enzymes catalyze the conversion 3-keto-Δ4-steroids to their 5α-reduced congeners. In the genital skin and prostate, the type 2 isoenzyme converts testosterone (T) to the more potent androgen 5α-dihydrotestosterone (DHT), and intracellular DHT is essential for the morphogenesis of the undifferentiated external genitalia to the male phenotype. Both isoenzymes also metabolize other 19- and 21-carbon 3-keto-Δ4-steroids, both endogenous compounds and some steroid-based drugs. Rigorous biochemical studies have been limited due to the extremely hydrophobic nature of these proteins. We have described the heterologous expression of these enzymes in bacteria, their purification with affinity chromatography, and the reconstitution of activity in liposomes. This article details these procedures, as well as reconstitution in phospholipid nanodiscs and enzyme assay.

Long-term efficacy and safety of osilodrostat in patients with Cushing's disease: results from the LINC 4 study extension.

Objective: To evaluate the long-term efficacy and safety of osilodrostat in patients with Cushing's disease. Methods: The multicenter, 48-week, Phase III LINC 4 clinical trial had an optional extension period that was initially intended to continue to week 96. Patients could continue in the extension until a managed-access program or alternative treatment became available locally, or until a protocol amendment was approved at their site that specified that patients should come for an end-of-treatment visit within 4 weeks or by week 96, whichever occurred first. Study outcomes assessed in the extension included: mean urinary free cortisol (mUFC) response rates; changes in mUFC, serum cortisol and late-night salivary cortisol (LNSC); changes in cardiovascular and metabolic-related parameters; blood pressure, waist circumference and weight; changes in physical manifestations of Cushing's disease; changes in patient-reported outcomes for health-related quality of life; changes in tumor volume; and adverse events. Results were analyzed descriptively; no formal statistical testing was performed. Results: Of 60 patients who entered, 53 completed the extension, with 29 patients receiving osilodrostat for more than 96 weeks (median osilodrostat duration: 87.1 weeks). The proportion of patients with normalized mUFC observed in the core period was maintained throughout the extension. At their end-of-trial visit, 72.4% of patients had achieved normal mUFC. Substantial reductions in serum cortisol and LNSC were also observed. Improvements in most cardiovascular and metabolic-related parameters, as well as physical manifestations of Cushing's disease, observed in the core period were maintained or continued to improve in the extension. Osilodrostat was generally well tolerated; the safety profile was consistent with previous reports. Conclusion: Osilodrostat provided long-term control of cortisol secretion that was associated with sustained improvements in clinical signs and physical manifestations of hypercortisolism. Osilodrostat is an effective long-term treatment for patients with Cushing's disease. Clinical trial registration: ClinicalTrials.gov, identifier NCT02180217.

Approaching Primary Aldosteronism as a Common Disease.

OBJECTIVE: To describe the approach to primary aldosteronism as a common disease. METHODS: The study methods involved are literature review and personal experience. RESULTS: Primary aldosteronism is the most common form of endocrine hypertension, yet screening rates are abysmally low. Major reasons for low screening rates include misconceptions about the drug interference and limited access to adrenal vein sampling expertise for subtyping. The workup of primary aldosteronism is greatly simplified by considering the condition as a continuum with low-renin primary hypertension. Thus, the purpose of the evaluation is not a yes/no dichotomous diagnosis but rather a gauging of how likely the patient has a lateralized source and will benefit from unilateral adrenalectomy. This approach favors the selective rather than universal use of cross-sectional imaging and adrenal vein sampling but promotes the liberal use of mineralocorticoid-receptor antagonists. CONCLUSION: The review will develop a practical approach to the patient using a series of questions with answers from the literature.

Influence of cholesterol on kinetic parameters for human aromatase (P450 19A1) in phospholipid nanodiscs.

Cholesterol, a significant constituent of the endoplasmic reticulum membrane, exerts a substantial effect on the membrane's biophysical and mechanical properties. Cholesterol, however, is often neglected in model systems used to study membrane-bound proteins. For example, the influence of cholesterol on the enzymatic functions of type 2 cytochromes P450, which require a phospholipid bilayer and the redox partner P450-oxidoreductase (POR) for activity, are rarely investigated. Human aromatase (P450 19A1) catalyzes three sequential oxygenations of 19­carbon steroids to estrogens and is widely expressed across various tissues, which are characterized by varying cholesterol compositions. Our study examined the impact of cholesterol on the functionality of the P450 19A1 complex with POR. Nanodiscs containing P450 19A1 with 20% cholesterol/80% phospholipid had similar rates and affinity of androstenedione binding as phospholipid-only P450 19A1 nanodiscs, and rates of product formation were indistinguishable among these conditions. In contrast, the rate of the first electron transfer from POR to P450 19A1 was 3-fold faster in cholesterol-containing nanodiscs than in phospholipid-only nanodiscs. These results suggest that cholesterol influences some aspects of POR interaction with P450 19A1 and might serve as an additional regulatory mechanism in this catalytic system.

Hormones and Aging: An Endocrine Society Scientific Statement.

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

ß-Catenin-Driven Differentiation Is a Tissue-Specific Epigenetic Vulnerability in Adrenal Cancer.

Adrenocortical carcinoma (ACC) is a rare cancer in which tissue-specific differentiation is paradoxically associated with dismal outcomes. The differentiated ACC subtype CIMP-high is prevalent, incurable, and routinely fatal. CIMP-high ACC possess abnormal DNA methylation and frequent ß-catenin-activating mutations. Here, we demonstrated that ACC differentiation is maintained by a balance between nuclear, tissue-specific ß-catenin-containing complexes, and the epigenome. On chromatin, ß-catenin bound master adrenal transcription factor SF1 and hijacked the adrenocortical super-enhancer landscape to maintain differentiation in CIMP-high ACC; off chromatin, ß-catenin bound histone methyltransferase EZH2. SF1/ß-catenin and EZH2/ß-catenin complexes present in normal adrenals persisted through all phases of ACC evolution. Pharmacologic EZH2 inhibition in CIMP-high ACC expelled SF1/ß-catenin from chromatin and favored EZH2/ß-catenin assembly, erasing differentiation and restraining cancer growth in vitro and in vivo. These studies illustrate how tissue-specific programs shape oncogene selection, surreptitiously encoding targetable therapeutic vulnerabilities. SIGNIFICANCE: Oncogenic ß-catenin can use tissue-specific partners to regulate cellular differentiation programs that can be reversed by epigenetic therapies, identifying epigenetic control of differentiation as a viable target for ß-catenin-driven cancers.

Testosterone histories from tusks reveal woolly mammoth musth episodes.

Hormones in biological media reveal endocrine activity related to development, reproduction, disease and stress on different timescales1. Serum provides immediate circulating concentrations2, whereas various tissues record steroid hormones accumulated over time3,4. Hormones have been studied in keratin, bones and teeth in modern5-8 and ancient contexts9-12; however, the biological significance of such records is subject to ongoing debate10,13-16, and the utility of tooth-associated hormones has not previously been demonstrated. Here we use liquid chromatography with tandem mass spectrometry paired with fine-scale serial sampling to measure steroid hormone concentrations in modern and fossil tusk dentin. An adult male African elephant (Loxodonta africana) tusk shows periodic increases in testosterone that reveal episodes of musth17-19, an annually recurring period of behavioural and physiological changes that enhance mating success20-23. Parallel assessments of a male woolly mammoth (Mammuthus primigenius) tusk show that mammoths also experienced musth. These results set the stage for wide-ranging studies using steroids preserved in dentin to investigate development, reproduction and stress in modern and extinct mammals. Because dentin grows by apposition, resists degradation, and often contains growth lines, teeth have advantages over other tissues that are used as records of endocrine data. Given the low mass of dentin powder required for analytical precision, we anticipate dentin-hormone studies to extend to smaller animals. Thus, in addition to broad applications in zoology and palaeontology, tooth hormone records could support medical, forensic, veterinary and archaeological studies.

Crinecerfont, a CRF1 Receptor Antagonist, Lowers Adrenal Androgens in Adolescents With Congenital Adrenal Hyperplasia.

CONTEXT: Crinecerfont, a corticotropin-releasing factor type 1 receptor antagonist, has been shown to reduce elevated adrenal androgens and precursors in adults with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD), a rare autosomal recessive disorder characterized by cortisol deficiency and androgen excess due to elevated adrenocorticotropin. OBJECTIVE: To evaluate the safety, tolerability, and efficacy of crinecerfont in adolescents with 21OHD CAH. METHODS: This was an open-label, phase 2 study (NCT04045145) at 4 centers in the United States. Participants were males and females, 14 to 17 years of age, with classic 21OHD CAH. Crinecerfont was administered orally (50 mg twice daily) for 14 consecutive days with morning and evening meals. The main outcomes were change from baseline to day 14 in circulating concentrations of ACTH, 17-hydroxyprogesterone (17OHP), androstenedione, and testosterone. RESULTS: 8 participants (3 males, 5 females) were enrolled; median age was 15 years and 88% were Caucasian/White. After 14 days of crinecerfont, median percent reductions from baseline to day 14 were as follows: ACTH, -57%; 17OHP, -69%; and androstenedione, -58%. In female participants, 60% (3/5) had ≥50% reduction from baseline in testosterone. CONCLUSION: Adolescents with classic 21OHD CAH had substantial reductions in adrenal androgens and androgen precursors after 14 days of oral crinecerfont administration. These results are consistent with a study of crinecerfont in adults with classic 21OHD CAH.

Selectivity of osilodrostat as an inhibitor of human steroidogenic cytochromes P450.

Osilodrostat (LCI699) is a potent inhibitor of the human steroidogenic cytochromes P450 11ß-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2). LCI699 is FDA-approved for the treatment of Cushing disease, which is characterized by chronic overproduction of cortisol. While phase II and III clinical studies have proven the clinical efficacy and tolerability of LCI699 for treating Cushing disease, few studies have attempted to fully assess the effects of LCI699 on adrenal steroidogenesis. To this end, we first comprehensively analyzed LCI699-mediated inhibition of steroid synthesis in the NCI-H295R human adrenocortical cancer cell line. We then studied LCI699 inhibition using HEK-293 or V79 cells stably expressing individual human steroidogenic P450 enzymes. Our studies using intact cells confirm the potent inhibition of CYP11B1 and CYP11B2 with negligible inhibition of 17-hydroxylase/17,20-lyase (CYP17A1) and 21-hydroxylase (CYP21A2). Furthermore, partial inhibition of the cholesterol side-chain cleavage enzyme (CYP11A1) was observed. To calculate the dissociation constant (Kd) of LCI699 with the adrenal mitochondrial P450 enzymes, we successfully incorporated P450s into lipid nanodiscs and carried out spectrophotometric equilibrium and competition binding assays. Our binding experiments confirm the high affinity of LCI699 to CYP11B1 and CYP11B2 (Kd ≈ 1 nM or less) and much weaker binding for CYP11A1 (Kd = 18.8 µM). Our results confirm the selectivity of LCI699 for CYP11B1 and CYP11B2 and demonstrate partial inhibition of CYP11A1 but not CYP17A1 and CYP21A2.

Interpretation of Steroid Biomarkers in 21-Hydroxylase Deficiency and Their Use in Disease Management.

The most common form of congenital adrenal hyperplasia is 21-hydroxylase deficiency (21OHD), which in the classic (severe) form occurs in roughly 1:16 000 newborns worldwide. Lifelong treatment consists of replacing cortisol and aldosterone deficiencies, and supraphysiological dosing schedules are typically employed to simultaneously attenuate production of adrenal-derived androgens. Glucocorticoid titration in 21OHD is challenging as it must balance the consequences of androgen excess vs those from chronic high glucocorticoid exposure, which are further complicated by interindividual variability in cortisol kinetics and glucocorticoid sensitivity. Clinical assessment and biochemical parameters are both used to guide therapy, but the specific purpose and goals of each biomarker vary with age and clinical context. Here we review the approach to medication titration for children and adults with classic 21OHD, with an emphasis on how to interpret adrenal biomarker values in guiding this process. In parallel, we illustrate how an understanding of the pathophysiologic and pharmacologic principles can be used to avoid and to correct complications of this disease and consequences of its management using existing treatment options.

Long-term cardiometabolic morbidity in young adults with classic 21-hydroxylase deficiency congenital adrenal hyperplasia.

PURPOSE: To study the current practice for assessing comorbidity in adults with 21-hydroxylase CAH and to assess the prevalence of comorbidity in these adults. METHODS: A structured questionnaire was sent to 46 expert centres managing adults with CAH. Information collected included current therapy and surveillance practice with a particular focus on osteoporosis/osteopaenia, hyperlipidaemia, type 2 diabetes/hyperinsulinaemia, hypertension, CV disease, obesity. RESULTS: Of the 31 (67%) centres from 15 countries that completed the survey, 30 (97%) screened for hypertension by measuring blood pressure, 30 (97%) screened for obesity, 26 (84%) screened for abnormal glucose homoeostasis mainly by using Hb1Ac (73%), 25 (81%) screened for osteoporosis mainly by DXA (92%), 20 (65%) screened for hyperlipidaemia and 6 (19%) screened for additional CV disease. Of the 31 centres, 13 provided further information on the six co-morbidities in 244 patients with a median age of 33 yrs (range 19, 94). Of these, 126 (52%) were females and 174 (71%) received fludrocortisone in addition to glucocorticoids. Of the 244 adults, 73 (30%) were treated for at least one comorbidity and 15 (21%) for more than 2 co-morbidities. Of 73, the patients who were treated for osteoporosis/osteopaenia, hyperlipidaemia, type 2 diabetes/hyperinsulinaemia, hypertension, CV disease, obesity were 43 (59%), 17 (23%), 16 (22%), 10 (14%), 8 (11), 3 (4%) respectively. CONCLUSION: Cardiometabolic and bone morbidities are not uncommon in adults with CAH. There is a need to standardise the screening for these morbidities from early adulthood and to explore optimal therapy through routine collection of standardised data.