Adrenal Mass: Insight Into Pathogenesis and a Common Link With Insulin Resistance

Sensitivity of the Neuroendocrine Stress Axis in Metabolic Diseases

Metabolic diseases are prevalent in modern society and have reached pandemic proportions. Metabolic diseases have systemic effects on the body and can lead to changes in the neuroendocrine stress axis, the critical regulator of the body's stress response. These changes may be attributed to rising insulin levels and the release of adipokines and inflammatory cytokines by adipose tissue, which affect hormone production by the neuroendocrine stress axis. Chronic stress due to inflammation may exacerbate these effects. The increased sensitivity of the neuroendocrine stress axis may be responsible for the development of metabolic syndrome, providing a possible explanation for the high prevalence of severe comorbidities such as heart disease and stroke associated with metabolic disease. In this review, we address current knowledge of the neuroendocrine stress axis in response to metabolic disease and discuss its role in developing metabolic syndrome.

A Brief Look at Hashimoto's Disease, Adrenal Incidentalomas, Obesity and Insulin Resistance-Could Endocrine Disruptors Be the Other Side of the Same Coin?

Hashimoto's disease (HD) is the most common cause of hypothyroidism in developed countries. The exact pathomechanism behind it has not been clearly established; however, an interplay of genetic susceptibility, environmental triggers (including diet) and epigenetic factors seems to be involved. Among the latter, increasingly more attention has been paid to some hormonally active substances, known as endocrine disruptors, which are commonly used worldwide. HD has become a condition widely reported in the media, acting as a culprit for inexplicable weight gain, chronic fatigue or weakness. Nevertheless, the recognition of HD is undeniably increasing and represents a major public health burden. At the same time, improving access to imaging tests has increased the number of incidentally diagnosed adrenal tumors. Above all, the widespread use of chest computed tomography (CT) due to the COVID-19 pandemic has contributed to frequent incidental detection of adrenal lesions. Fortunately, a vast majority of these findings are asymptomatic benign tumors with no excessive hormonal activity, and therefore, they are defined as adrenal incidentalomas (AIs). Interestingly, recent studies have indicated that patients with AIs are more prone to obesity and insulin resistance. Although mutual relationships between the thyroid and the adrenal glands have been studied widely, still, little is known about the possible pathophysiological associations between thyroid autoimmunity and the occurrence of adrenal incidentalomas. This article presents a brief review of the common endocrine disorders with a special focus on the frequently coexisting insulin resistance and/or obesity. Furthermore, in response to the recent growing interest in endocrine disruptors, with their transgenerational epigenetic effects that influence hormonal system function, a concise overview of the topic has also been included.

Pathophysiological Link between Insulin Resistance and Adrenal Incidentalomas

Adrenal incidentalomas are incidentally discovered adrenal masses greater than one centimeter in diameter. An association between insulin resistance and adrenal incidentalomas has been established. However, the pathophysiological link between these two conditions remains incompletely characterized. This review examines the literature on the interrelationship between insulin resistance and adrenal masses, their subtypes, and related pathophysiology. Some studies show that functional and non-functional adrenal masses elicit systemic insulin resistance, whereas others conclude the inverse. Insulin resistance, hyperinsulinemia, and the anabolic effects on adrenal gland tissue, which have insulin and insulin-like growth factor-1 receptors, offer possible pathophysiological links. Conversely, autonomous adrenal cortisol secretion generates visceral fat accumulation and insulin resistance. Further investigation into the mechanisms and timing of these two pathologies as they relate to one another is needed and could be valuable in the prevention, detection, and treatment of both conditions.

Adipose-specific knockout of ubiquitin-conjugating enzyme E2L6 (Ube2l6) reduces diet-induced obesity, insulin resistance, and hepatic steatosis

Ubiquitin/ISG15-conjugating enzyme E2 L6 (UBE2L6/Ube2l6) catalyzes protein ISGylation and ubiquitylation, post-translational modifications which regulate protein stability. Ube2l6 plays a role in promoting in vitro adipogenesis; however, its mechanism(s) of action and in vivo effects remain unknown. Here, we discovered that UBE2L6 levels were upregulated, and UBE2L6 and adipose triglyceride lipase (ATGL/Atgl) levels were negatively correlated, in white adipose tissue (WAT) from obese humans and obese mice. Therefore, we employed adipose-specific Ube2l6 knockout (Ube2l6^AKO) mice and age-matched Ube2l6^flox/flox controls to assess adipocyte Ube2l6's role in high-fat diet (HFD)-induced obesity, insulin resistance, and hepatic steatosis. HFD-fed Ube2l6^AKO mice displayed lower subcutaneous and visceral WAT mass levels relative to controls. HFD-fed Ube2l6^AKO mice also showed WAT adipocyte hypoplasia and hypotrophy as well as enhanced whole-body metabolic activity relative to controls. Furthermore, glucose intolerance, insulin resistance, compensatory hyperinsulinemia, hypercholesterolemia, and hepatic steatosis were lower in HFD-fed Ube2l6^AKO mice as compared to controls. Mechanistically, we found that Atgl protein expression and Atgl-mediated lipolysis were negatively regulated by Ube2l6's promotion of Atgl protein ubiquitylation. Collectively, adipocyte Ube2l6 functions as a negative regulator of Atgl protein stability and, consequently, promotes HFD-induced obesity, insulin resistance, and hepatic steatosis.

Is there a role for the IGF system and epidermal growth factor (EGF) in the pathogenesis of adrenocortical adenomas? A preliminary case-control study

Adrenal incidentalomas (AI) are very common and mostly they are non-functioning adenomas (NFA). NFAs are often associated with insulin resistance and metabolic syndrome. Several biomarkers, including certain growth factors, may participatein the pathogenesis ofmetabolic changes in patients with adrenal adenomas.Patients with NFA and age-matched control subjects were enrolled in the study. Data on age, gender, presence of metabolic syndrome or its components were obtained for each subject. Blood samples were obtained and glycemia, insulinemia, lipid profile, and selected growth factor levels were measured. Forty-three patients with NFA and 40 controls were included in the study. Differences were not found in the metabolic syndrome and its components prevalence or in the biochemical profile between patients and the control group. Significant differences were noticed in the levels of IGF1, IGF2, and IGFBP3 (p=0.016, p=0.005, p=0.004, respectively), but there were no differences in VEGF or EGF concentrations. In NFA patients, an association between glycemia and EGF levels was present (p=0.026). No significant correlations between tumor size and insulin or growth factor concentrations were present in AI patients. Significantly higher serum IGF1, IGF2, and IGFBP3 concentrations in NFA patients may support the role of the IGF axis in the pathogenesis of adrenocortical lesions.No correlation between IGFs or IGFBP3 and parameters of glucose or lipid metabolism was found. Present results may support the role of the growth hormone axis rather than hyperinsulinemia and insulin resistance in the pathogenesis of adrenocortical adenomas.

The prevalence and characteristics of non-functioning and autonomous cortisol secreting adrenal incidentaloma after patients' stratification by body mass index and age

BACKGROUND

The escalating prevalence of adrenal incidentaloma (AI) has been associated with the improvement of radiologic techniques and widespread imaging in aging population. It is currently unclear whether patients with obesity more likely develop AI and the current rise in the prevalence of AI could be at least partly associated with the respective rise in obesity. We compared the prevalence and characteristics of non-functional (NF) and autonomous cortisol secreting (ACS) adrenal incidentalomas (AIs) after the study population was stratified by different body mass indexes (BMI) and age groups.

METHODS

Retrospective cross-sectional study comprising of 432 patients (40.6% male, 59.4% female) with NFAI (N = 290) and ACS (N = 142), of median age 63.4 (54.0-71.6) years and median BMI 28.6 (25.5-31.7) kg/m². The data collection contained 11.132 points including demographic, anthropometric, radiologic, hormonal and metabolic parameters.

RESULTS

We observed 68-87% higher prevalence of AI across different age groups in NFAI and ACS in obese/overweight compared to normal weight subjects. Patients with ACS were older (P = 0.008), with higher basal cortisol (P < 0.001), lower basal DHEAS (P = 0.001), lower suppression DHEAS (P = 0.027) and higher aldosterone (P = 0.039). AIs with ACS were larger than NFAI (P < 0.001). Interestingly, ACS group had lower body mass (P = 0.023) and did not differ in BMI, blood pressure, heart rate, lipid profile, fasting glucose and presence of diabetes mellitus type 2 when compared to NFAI., By contrast to the similarity of metabolic profiles in ACS and NFAI, some components of adverse metabolic traits were rather associated with higher BMI and older age, in particular in NFAI.

CONCLUSION

The prevalence of NFAI and ACS were significantly higher in overweight/obese subgroup across the age distribution. Stratification by age and BMI displayed significant differences in some metabolic traits, in particular in NFAI.

Pleomorphic Leiomyosarcoma of the Adrenal Gland in a Young Woman: A Case Report and Review of the Literature

Leiomyosarcoma usually arises in the uterus, abdominal and urologic viscera, and walls of large and small blood vessels. However, primary adrenal leiomyosarcoma is extremely rare with only 39 cases previously reported in English-language literature. We report a case of a 29-year-old previously healthy woman with an incidentally found right adrenal-occupying lesion. CT scan revealed a right adrenal mass measuring 3.3×3.4 cm in size. The tumor was successfully removed by laparoscopic adrenalectomy. Postoperative histopathologic examination showed spindle cells arranged in interlacing fascicles with pleomorphism and a high mitotic rate. An immunohistochemical examination showed positive staining for SMA, desmin, vimentin and H-caldesmon, and the diagnosis of a well-differentiated adrenal leiomyosarcoma was established. The patient received no other oncological treatment after surgery and currently has no evidence of residual disease or tumor recurrence according to imaging follow-up.

Biochemical and clinical characteristics of patients with primary aldosteronism: Single centre experience

Background

Primary aldosteronism (PA) is associated with increased prevalence of metabolic disorders (impaired glucose and lipid metabolism and insulin resistance), but also with more frequent cardiovascular, renal and central nervous system complications.

Methods

Biochemical and clinical parameters were retrospectively analysed for 40 patients with PA caused by aldosterone-producing adenoma (APA) and compared to the control groups of 40 patients with nonfunctioning adrenal adenoma (NFA) and essential hypertension (HT), and 20 patients with adrenal Cushing syndrome (CS) or subclinical CS (SCS).

Results

Systolic, diastolic and mean arterial blood pressures were significantly higher in the PA group (p=0.004; p=0.002; p=0.001, respectively) than in NFA+HT group. PA patients had longer hypertension history (p=0.001) than patients with hypercorticism and all had hypokalaemia. This group showed the smallest mean tumour diameter (p<0.001). The metabolic syndrome was significantly less common in the PA group (37.5% vs. 70% in CS+SCS and 65% in NFA+HT group; p=0.015), although there was no significant difference in any of the analysed metabolic parameters between groups. PA group was found to have the most patients with glucose intolerance (81.8%), although the difference was not significant. The mean BMI for all three groups was in the overweight range. Patients with PA had higher microalbuminuria and a higher tendency for cardiovascular, renal and cerebrovascular events, but the difference was not significant.

Conclusions

Our results support the importance of the early recognition of primary aldosteronism on the bases of clinical presentation, as well as an increased screening intensity.

Adrenal morphology and associated comorbidities in congenital adrenal hyperplasia

OBJECTIVE

Adrenonodular hyperplasia and tumour formation are potential long-term complications of congenital adrenal hyperplasia (CAH) with little known regarding the clinical implications. Our aim was to describe volumetric adrenal morphology and determine the association between radiological findings and comorbidities in adults with classic CAH.

DESIGN

This was a cross-sectional study of 88 patients (mean age 29.2 ± 13 years, 47 females) with classic CAH seen in a tertiary referral centre.

METHODS

CT imaging, performed at study entry or when reaching adulthood, was used to create 3-dimensional volumetric models. Clinical, genetic and hormonal evaluations were collected and correlated with adrenal morphology and tumour formation.

RESULTS

Over one-third of the cohort was obese. 53% had elevated 17-OH-progesterone or androstenedione; and 60% had adrenal hyperplasia. Tumours included 11 myelolipomas, 8 benign adrenocortical adenomas, 1 pheochromocytoma and 50% of men had testicular adrenal rest tissue. CAH patients with adrenal hyperplasia had significantly higher number of comorbidities than those with morphologically normal adrenals (P = 0.03). Variables that positively correlated with adrenal volume included hypogonadal/oligomenorrhoeic status, hypertension, androstenedione, aldosterone, and triglyceride levels, and in women, low HDL and insulin resistance. Elevated aldosterone was observed in a subset of patients with simple virilizing CAH.

CONCLUSIONS

Adrenocortical hyperplasia is associated with a number of comorbidities, especially hypogonadism. Aldosterone production associated with adrenal enlargement may play a role in the development of metabolic risk factors. Further studies are needed to assess the long-term impact of the excess adrenal steroid milieu associated with adrenal enlargement to develop improved management strategies for CAH.

Insulin resistance and adrenal incidentalomas: A bidirectional relationship

An adrenal incidentaloma (AI) is an adrenal mass incidentally found via a radiological modality, independent of an endocrinological investigation. In this review, we aimed to investigate the possible reasons behind the increased frequency in AI detection, especially in ageing populations. The pathophysiological effects of insulin resistance (IR), hyperinsulinemia and various anabolic pathways are analyzed. In addition, we review data from studies indicating an increased incidence of adrenal adenomas and carcinomas in patients with type 2 diabetes mellitus (T2DM). The establishment of obesity as a global epidemic, with a higher prevalence in the female than in the male population, coincide with data regarding AIs and the conditions may share a pathophysiological basis. Furthermore, we discuss the bidirectional association of AIs with obesity, insulin resistance and T2DM, especially in patients with autonomous cortisol secretion. Lastly, as per the definition of an AI, we touch upon the evolution of radiological imaging as another possible cause of the rise in prevalence of AIs, especially concerning the greater use and precision of computed tomography (CT).

Autophagy as an emerging target in cardiorenal metabolic disease: From pathophysiology to management

Although advances in medical technology and health care have improved the early diagnosis and management for cardiorenal metabolic disorders, the prevalence of obesity, insulin resistance, diabetes, hypertension, dyslipidemia, and kidney disease remains high. Findings from numerous population-based studies, clinical trials, and experimental evidence have consolidated a number of theories for the pathogenesis of cardiorenal metabolic anomalies including resistance to the metabolic action of insulin, abnormal glucose and lipid metabolism, oxidative and nitrosative stress, endoplasmic reticulum (ER) stress, apoptosis, mitochondrial damage, and inflammation. Accumulating evidence has recently suggested a pivotal role for proteotoxicity, the unfavorable effects of poor protein quality control, in the pathophysiology of metabolic dysregulation and related cardiovascular complications. The ubiquitin-proteasome system (UPS) and autophagy-lysosomal pathways, two major although distinct cellular clearance machineries, govern protein quality control by degradation and clearance of long-lived or damaged proteins and organelles. Ample evidence has depicted an important role for protein quality control, particularly autophagy, in the maintenance of metabolic homeostasis. To this end, autophagy offers promising targets for novel strategies to prevent and treat cardiorenal metabolic diseases. Targeting autophagy using pharmacological or natural agents exhibits exciting new strategies for the growing problem of cardiorenal metabolic disorders.

Metabolic Stress, Autophagy, and Cardiovascular Aging: from Pathophysiology to Therapeutics

Recent advances in health care have improved the management of cardiometabolic disorders, and prolonged lifespan. However, the ever-rising prevalence of metabolic stress related to obesity (insulin resistance, diabetes, hypertension, and dyslipidemia) has greatly challenged geriatric care. The ubiquitin-proteasome system and autophagy-lysosomal pathways represent two major, yet distinct cellular machineries, for degradation and removal of damaged or long-lived proteins and organelles; the function of which declines with aging. To seek new strategies for cardiovascular aging under various metabolic diseases, it is imperative to understand the precise role for metabolic stress and protein quality control, in particular autophagy, in premature cardiovascular aging. Targeting metabolic stress and autophagy may offer exciting new avenues for the management of cardiovascular aging.

The Role of Insulin Resistance/Hyperinsulinism on the Rising Trend of Thyroid and Adrenal Nodular Disease in the Current Environment

Thyroid follicular cells, as well as adrenocortical cells, are endowed by an intrinsic heterogeneity regarding their growth potential, in response to various stimuli. This heterogeneity appears to constitute the underlying cause for the focal cell hyperplasia and eventually the formation of thyroid and adrenal nodules, under the influence of growth stimulatory factors. Among the main stimulatory factors are the pituitary tropic hormones, thyroid-stimulating hormone (TSH) or thyrotropin and adrenocorticotropic hormone (ACTH), which regulate the growth and function of their respective target cells, and the insulin/insulin-like growth factor system, that, through its mitogenic effects, can stimulate the proliferation of these cells. The predominance of one or the other of these growth stimulatory factors appears to determine the natural history of thyroid and adrenal nodular disease. Thus, iodine deficiency was, in the past, the main pathogenic factor responsible, through a transient rise in TSH secretion, for the endemic nodular goiter with the characteristic colloid thyroid nodules among the inhabitants in iodine deficient areas. The correction of iodine deficiency was followed by the elimination of endemic colloid goiter and the emergence of thyroid autoimmunity. The recent epidemic of obesity and metabolic syndrome (MS), or insulin resistance syndrome, has been associated with the re-emergence of nodular thyroid disease. A parallel rise in the incidence of benign, nonfunctional adrenocortical tumors, known as adrenal incidentalomas, has also been reported in association with the manifestations of the MS. It is likely that the compensatory to insulin resistance hyperinsulinemia may be responsible for the rising trend of thyroid and adrenal nodular disease in the current environment.