Rationale for treatment and therapeutic options in Cushing's disease

The sex-dependent response to psychosocial stress and ischaemic heart disease

Stress is an important risk factor for modern chronic diseases, with distinct influences in males and females. The sex specificity of the mammalian stress response contributes to the sex-dependent development and impacts of coronary artery disease (CAD). Compared to men, women appear to have greater susceptibility to chronic forms of psychosocial stress, extending beyond an increased incidence of mood disorders to include a 2- to 4-fold higher risk of stress-dependent myocardial infarction in women, and up to 10-fold higher risk of Takotsubo syndrome-a stress-dependent coronary-myocardial disorder most prevalent in post-menopausal women. Sex differences arise at all levels of the stress response: from initial perception of stress to behavioural, cognitive, and affective responses and longer-term disease outcomes. These fundamental differences involve interactions between chromosomal and gonadal determinants, (mal)adaptive epigenetic modulation across the lifespan (particularly in early life), and the extrinsic influences of socio-cultural, economic, and environmental factors. Pre-clinical investigations of biological mechanisms support distinct early life programming and a heightened corticolimbic-noradrenaline-neuroinflammatory reactivity in females vs. males, among implicated determinants of the chronic stress response. Unravelling the intrinsic molecular, cellular and systems biological basis of these differences, and their interactions with external lifestyle/socio-cultural determinants, can guide preventative and therapeutic strategies to better target coronary heart disease in a tailored sex-specific manner.

Broad Metabolome Alterations Associated with the Intake of Oral Contraceptives Are Mediated by Cortisol in Premenopausal Women

The use of oral contraceptives (OCs) has been associated with elevated blood cortisol concentrations. However, metabolic downstream effects of OC intake are not well described. Here, we aimed to determine if the blood metabolome is associated with the use of OCs and to estimate if these associations might be statistically mediated by serum cortisol concentrations. Plasma metabolites measured with the Biocrates AbsoluteIDQ p180 Kit and serum cortisol concentrations measured by an immunoassay were determined in 391 premenopausal women (116 OC users) participating in two independent cohorts of the Study of Health in Pomerania (SHIP). After correction for multiple testing, 27 metabolites were significantly associated with OC intake in SHIP-TREND (discovery cohort), of which 25 replicated in SHIP-2. Inter alia, associated metabolites included 12 out of 38 phosphatidylcholines with diacyl residue, 7 out of 14 lysophosphatidylcholines and 5 out of 21 amino acids. The associations with phosphatidylcholines were statistically mediated by cortisol, whereas lysophosphatidylcholines showed no mediation effect. The results represent a step toward a better understanding of the metabolic consequences of OC intake. Connecting cortisol with metabolic consequences of OC intake could help to understand the mechanisms underlying adverse effects. The blood metabolome may serve as a biomarker for identifying users at high risk for developing such adverse effects.

Glucocorticoid gene regulation of aquaporin-7

AQP7 is the primary glycerol transporter in white (WAT) and brown (BAT) adipose tissues. There are immediate and quantitatively important actions of cortisone over the expression of AQP7 in murine and human adipocytes. Short-term response (minutes) of cortisone treatment result in an mRNA overexpression in white and brown differentiated adipocytes (between 1.5 and 6 folds). Conversely, long-term response (hours or days) result in decreased mRNA expression. The effects observed on AQP7 mRNA expression upon cortisone treatment in brown and white differentiated adipocytes are concordant with those observed for GK and HSD1B11.

Should Cushing's Syndrome be Considered as a Disease with High Cardiovascular Risk in Relevant Guidelines?

A considerable amount of data supports a 1.8-7.4-fold increased mortality associated with Cushing's syndrome (CS). This is attributed to a high occurrence of several cardiovascular disease (CVD) risk factors in CS [e.g. adiposity, arterial hypertension (AHT), dyslipidaemia and type 2 diabetes mellitus (T2DM)]. Therefore, practically all patients with CS have the metabolic syndrome (MetS), which represents a high CVD risk. Characteristically, despite a relatively young average age, numerous patients with CS display a 'high' or 'very high' CVD risk (i.e. risk of a major CVD event >20% in the following 10 years). Although T2DM is listed as a condition with a high CVD risk, CS is not, despite the fact that a considerable proportion of the CS population will develop T2DM or impaired glucose tolerance. CS is also regarded as a risk factor for aortic dissection in current guidelines. This review considers the evidence supporting listing CS among high CVD risk conditions.

Chronic glucocorticoid treatment induced circadian clock disorder leads to lipid metabolism and gut microbiota alterations in rats

AIM

Glucocorticoids (GCs), steroid hormones synthetized by the adrenal gland, are regulated by circadian cycles, and dysregulation of GC signaling can lead to the development of metabolic syndrome. The effects and potential mechanism of GCs in physiology were investigated in the present study.

MAIN METHODS

Male Wistar rats were orally administered dexamethasone sodium phosphate (DEX, 0.01 and 0.05mg/kg body weight per day) for 7weeks.

KEY FINDING

DEX treatment attenuated body weight gain and reduced food intake, whereas it induced the accumulation of fat. Administration of DEX induced dysregulation of the expression of lipogenic genes in both fat and liver. Moreover, the mRNA levels of genes related to mitochondrial biogenesis and function were significantly downregulated in the liver and fat of DEX-treated rats. Furthermore, DEX treatment caused a significant reduction in the richness and diversity of the microbiota in the colon, as assessed using high-throughput sequencing of the 16s rRNA gene V3-V4 region, an increase in inflammatory cell infiltration, and a decrease in mucus secretion in the colon. Additionally, DEX administration induced phase shift or loss of circadian rhythmicity of clock-related genes in peripheral tissues. These results were associated with higher serum corticosterone levels and upregulation of GC receptor (GR) expression in peripheral tissues.

SIGNIFICANCE

Our findings indicate that long-term administration of GC caused lipid accumulation, changes in the structure of the intestinal flora, and reduced colonic mucus secretion in vivo. The mechanism of these physiological changes may involve a circadian rhythm disorder and dysregulation of GR expression.

The Metabolic Implications of Glucocorticoids in a High-Fat Diet Setting and the Counter-Effects of Exercise

Glucocorticoids (GCs) are steroid hormones, naturally produced by activation of the hypothalamic-pituitary-adrenal (HPA) axis, that mediate the immune and metabolic systems. Synthetic GCs are used to treat a number of inflammatory conditions and diseases including lupus and rheumatoid arthritis. Generally, chronic or high dose GC administration is associated with side effects such as steroid-induced skeletal muscle loss, visceral adiposity, and diabetes development. Patients who are taking exogenous GCs could also be more susceptible to poor food choices, but the effect that increasing fat consumption in combination with elevated exogenous GCs has only recently been investigated. Overall, these studies show that the damaging metabolic effects initiated through exogenous GC treatment are significantly amplified when combined with a high fat diet (HFD). Rodent studies of a HFD and elevated GCs demonstrate more glucose intolerance, hyperinsulinemia, visceral adiposity, and skeletal muscle lipid deposition when compared to rodents subjected to either treatment on its own. Exercise has recently been shown to be a viable therapeutic option for GC-treated, high-fat fed rodents, with the potential mechanisms still being examined. Clinically, these mechanistic studies underscore the importance of a low fat diet and increased physical activity levels when individuals are given a course of GC treatment.

The role of bilateral adrenalectomy in the treatment of refractory Cushing's disease

Cushing's syndrome (CS) results from sustained exposure to excessive levels of free glucocorticoids. One of the main causes of CS is excessive adrenocorticotropic hormone (ACTH) secretion by tumors in the pituitary gland (Cushing's disease [CD]). Cushing's disease and its associated hypercortisolism have a breadth of debilitating symptoms associated with an increased mortality rate, warranting urgent treatment. Currently, the first line of treatment for CD is transsphenoidal surgery (TSS), with excellent long-term results. Transsphenoidal resections performed by experienced surgeons have shown remission rates ranging from 70% to 90%. However, some patients do not achieve normalization of their hypercortisolemic state after TSS and continue to have persistent or recurrent CD. For these patients, various therapeutic options after failed TSS include repeat TSS, radiotherapy, medical therapy, and bilateral adrenalectomy (BLA). Bilateral adrenalectomy has been shown to be a safe and effective treatment modality for persistent or recurrent CD with an immediate and definitive cure of the hypercortisolemic state. BLA was traditionally performed through an open approach, but since the advent of laparoscopic adrenalectomy, the laparoscopic approach has become the surgical method of choice. Advances in technology, refinement in surgical skills, competency in adrenopathology, and emphasis on multidisciplinary collaborations have greatly reduced morbidity and mortality associated with adrenalectomy surgery in a high-risk patient population. In this article, the authors review the role of BLA in the treatment of refractory CD. The clinical indications, current surgical and endocrinological results reported in the literature, surgical technique (open vs laparoscopic), drawbacks, and complications of BLA are discussed.

Cushing's syndrome: an update on current pharmacotherapy and future directions

INTRODUCTION

Endogenous Cushing's syndrome (CS) is characterized by chronic overproduction of cortisol and is associated with increased mortality and morbidity. It can be caused by a pituitary adenoma, ectopic adrenocorticotropic hormone (ACTH) production or primary adrenal disease. Successful tumor-directed surgery is the keystone treatment. When surgery is unsuccessful, contraindicated or in case of acute disease, pharmacotherapy is indicated to treat hypercortisolism.

AREAS COVERED

In this review, pharmacotherapeutic options for CS will be covered discussing the different possible targets, that is: i) inhibition of ACTH secretion; ii) suppression of steroidogenesis; and iii) blockade of cortisol effects at tissue level. Preclinical and clinical studies will be discussed considering mono- and combination therapy, taking into account efficacy, toxicity and mechanism of action. Per CS entity, future directions of pharmacotherapies will be addressed.

EXPERT OPINION

The number of medical treatment options for CS has increased in the past years. In contrast to decades ago, prospective trials are now being performed focusing on pituitary-directed drugs like pasireotide, the glucocorticoid receptor blocker mifepristone and 'new generation' steroid synthesis inhibitors. Future studies will focus on tumor-shrinking effects of neuromodulatory drugs, the optimal order and combination of pharmacotherapy, long-term efficacy and safety and new targets for medical treatment of CS.

Pituitary-directed medical therapy in Cushing's disease

Transsphenoidal surgery remains the first line therapy in Cushing's disease, but a large number of patients will not be cured or disease will recur over time. Repeat pituitary surgery, bilateral adrenalectomy, and radiation have limitations with respect to efficacy and/or side effects. Therefore, there is a clear need for an effective medical treatment. The studies reviewed here suggest a role for pituitary-directed therapies, applying multireceptor ligand somatostatin analogs like pasireotide or second-generation dopamine agonists. Retinoic acid has been also studied in a small prospective study. These compounds target ACTH-secretion at the pituitary level and possibly inhibit corticotrope proliferation. Specific side effects of these compounds need to be considered, especially when used as long-term therapy. These novel approaches could provide options for treatment of patients in whom surgery has failed or is not possible, and while awaiting effects of radiation therapy. Preoperative use to decrease cortisol excess, potentially reducing perioperative complications, needs to be further studied.

Molecular basis of pharmacological therapy in Cushing's disease

Cushing's disease (CD) is a severe endocrine condition caused by an adrenocorticotropin (ACTH)-producing pituitary adenoma that chronically stimulates adrenocortical cortisol production and with potentially serious complications if not or inadequately treated. Active CD may produce a fourfold increase in mortality and is associated with significant morbidities. Moreover, excess mortality risk may persist even after CD treatment. Although predictors of risk in treated CD are not fully understood, the importance of early recognition and adequate treatment is well established. Surgery with resection of a pituitary adenoma is still the first line therapy, being successful in about 60-70 % of patients; however, recurrence within 2-4 years may often occur. When surgery fails, medical treatment can reduce cortisol production and ameliorate clinical manifestations while more definitive therapy becomes effective. Compounds that target hypothalamic-pituitary axis, glucocorticoid synthesis or adrenocortical function are currently used to control the deleterious effects of chronic glucocorticoid excess. In this review we describe and analyze the molecular basis of the drugs targeting the disease at central level, suppressing ACTH secretion, as well as at peripheral level, acting as adrenal inhibitors, or glucocorticoid receptor antagonists. Understanding of the underlying molecular mechanisms in CD and of glucocorticoid biology should promote the development of new targeted and more successful therapies in the future. Indeed, most of the drugs discussed have been tested in limited clinical trials, but there is potential therapeutic benefit in compounds with better specificity for the class of receptors expressed by ACTH-secreting tumors. However, long-term follow-up with management of persistent comorbidities is needed even after successful treatment of CD.

New developments in the medical treatment of Cushing's syndrome

Cushing's syndrome (CS) is a severe endocrine disorder characterized by chronic cortisol excess due to an ACTH-secreting pituitary adenoma, ectopic ACTH production, or a cortisol-producing adrenal neoplasia. Regardless of the underlying cause, untreated CS is associated with considerable morbidity and mortality. Surgery is the primary therapy for all causes of CS, but surgical failure and ineligibility of the patient to undergo surgery necessitate alternative treatment modalities. The role of medical therapy in CS has been limited because of lack of efficacy or intolerability. In recent years, however, new targets for medical therapy have been identified, both at the level of the pituitary gland (e.g. somatostatin, dopamine, and epidermal growth factor receptors) and the adrenal gland (ectopically expressed receptors in ACTH-independent macronodular adrenal hyperplasia). In this review, results of preclinical and clinical studies with drugs that exert their action through these molecular targets, as well as already established medical treatment options, will be discussed.

ACTH-secreting pituitary adenomas: size does not correlate with hormonal activity

ACTH-secreting pituitary adenomas (Cushing's disease, CD) are the most frequent cause of Cushing's syndrome. To test whether the size of ACTH-secreting adenomas correlates with the degree of biochemical and clinical features of hypercortisolism, we retrospectively reviewed all newly diagnosed CD patients seen at our institution by two neuro-endocrinologists over a 10-year time period. We documented the number of clinical manifestations and baseline hormonal measurements. There were 37 microadenomas (μAs) and 16 macroadenomas (MAs). We sought to characterize the relationship between tumor size (μA vs. MA) and number of signs and symptoms of hypercortisolism and biochemical assessment of hypercortisolemia. There were no significant differences in mean age, BMI, or prevalence of hypertension and type 2 diabetes between the μA and MA groups. However, the MAs had fewer clinical manifestations of hypercortisolism (29.4% vs. 36.1%, P = 0.02) compared to μAs. There was a higher prevalence of easy bruisability and proximal muscle weakness in the μAs, but otherwise the prevalence of signs and symptoms were similar between groups. The MAs had a lower random serum cortisol (18.2 ± 2.4 vs. 25.9 ± 1.8 mcg/dl, P = 0.018), lower cortisol:ACTH ratio (0.25 ± 0.03 vs. 0.42 ± 0.05, P < 0.048), and lower cortisol:tumor diameter ratio (14.1 ± 2.2 vs. 56.8 ± 7.2, P < 0.0001) than the μAs. We conclude that tumor size does not directly correlate with the extent of hormonal activity in ACTH-secreting adenomas. Biochemical activity and clinical manifestations may be mild even in larger tumors, and therefore a high index of suspicion may be necessary to recognize hypercortisolism in pituitary MAs.

The molecular pathogenesis of corticotroph tumours

BACKGROUND

The pathogenesis of tumour formation in the anterior pituitary including adrenocorticotropic hormone (ACTH)-secreting tumours has been intensively studied, but the causative mechanisms involved in pituitary cell transformation and tumourigenesis remain unclear.

MATERIALS AND METHODS

We searched PubMed on any paper related with molecular pathology of pituitary corticotroph adenomas and have included to this review all relevant references published up to June 2011.

RESULTS

Current studies increased our knowledge on the genetic basis of McCune-Albright syndrome (MAS), multiple endocrine neoplasia type 1 (MEN1), Carney complex (CNC), pituitary adenoma predisposition syndromes and tuberous sclerosis, but they have performed little to elucidate the causes of sporadic pituitary tumours including Cushing disease.

DISCUSSION

The aim of this review was to focus on the most recently published advances in the molecular pathology of corticotroph adenomas, which are presented in the context of changes seen in all types of pituitary adenomas, as well as in terms of corticotrophin-releasing hormone/ACTH/cortisol-specific pathways.

CONCLUSIONS

We would expect that over the next 5 years, more detailed analysis of inter-cellular communication pathways between pituitary cells, including the cadherins and integrins, and their interactions with other signalling pathways such as the β-catenin cascade will help elucidate what exactly goes awry in the formation of a benign corticotroph adenoma. This should in turn predict novel forms of pharmacological tumour control.

The effects of glucocorticoids on adipose tissue lipid metabolism

Glucocorticoids (GCs) have long been accepted as being catabolic in nature, liberating energy substrates during times of stress to supply the increased metabolic demand of the body. The effects of GCs on adipose tissue metabolism are conflicting, however, because patients with elevated GCs present with central adiposity. We performed an extensive literature review of the effects of GCs on adipose tissue metabolism. The contradictory effects of GCs on lipid metabolism occur through a number of different mechanisms, some of which are well defined and others remain to be elucidated. Firstly, through increases in caloric and dietary fat intake, along with increased hydrolysis of circulating triglycerides (chylomicrons, very low-density lipoproteins) by lipoprotein lipase activity, GCs increase the amount of fatty acids in circulation, which are then available for ectopic fat distribution (liver, muscle, and central adipocytes). Glucocorticoids also increase de novo lipid production in hepatocytes through increased expression of fatty acid synthase. There is some controversy as to whether these same mechanisms occur in adipocytes, thereby contributing to adipose hypertrophy. Glucocorticoids promote preadipocyte conversion to mature adipocytes, causing hyperplasia of the adipose tissue. Glucocorticoids also have acute antilipolytic effect on adipocytes, whereas their genomic actions facilitate increased lipolysis after about 48 hours of exposure. The acute and long-term effects of GCs on adipose tissue lipolysis remain unclear. Although considerable evidence supports the notion that GCs increase lipolysis through glucocorticoid-induced increases of lipase expression, they clearly have antilipolytic effects within these same tissues and cell line models.

Diagnosis and management of pituitary adenomas

PURPOSE OF REVIEW

Pituitary adenomas are frequently encountered in practice either because of clinical symptoms or as incidental findings. These tumors may alter pituitary function and can therefore have a considerable impact on morbidity, mortality, and quality of life.

RECENT FINDINGS

The presentation is variable for each type of tumor, with microadenomas being either silent or manifesting with symptoms of hormonal excess. In contrast, macroadenomas may present with mass effect. The various histologic types include prolactinomas, nonfunctioning adenomas, somatotropinomas, corticotropinomas, and thyrotropinomas. The present article will serve as an update on the diagnosis and treatment of pituitary adenomas. Advances in medical management for each tumor are discussed, highlighting new therapeutic alternatives. The role of surgery is also reviewed. Recommendations on the surveillance and postoperative monitoring of patients are emphasized.

SUMMARY

Newer methods in the diagnosis and treatment for pituitary adenomas greatly expand our ability to care for affected patients.

Update: Systemic Diseases and the Cardiovascular System (II). The endocrine system and the heart: a review

Normal endocrine function is essential for cardiovascular health. Disorders of the endocrine system, consisting of hormone hyperfunction and hypofunction, have multiple effects on the cardiovascular system. In this review, we discuss the epidemiology, diagnosis, and management of disorders of the pituitary, thyroid, parathyroid, and adrenal glands, with respect to the impact of endocrine dysfunction on the cardiovascular system. We also review the cardiovascular benefits of restoring normal endocrine function.

Update: Systemic Diseases and the Cardiovascular System (II). The endocrine system and the heart: a review

Normal endocrine function is essential for cardiovascular health. Disorders of the endocrine system, consisting of hormone hyperfunction and hypofunction, have multiple effects on the cardiovascular system. In this review, we discuss the epidemiology, diagnosis, and management of disorders of the pituitary, thyroid, parathyroid, and adrenal glands, with respect to the impact of endocrine dysfunction on the cardiovascular system. We also review the cardiovascular benefits of restoring normal endocrine function.