Genetic and potential autoimmune triggers of primary aldosteronism

Autoimmune Implications in a Patient with Graves' Hyperthyroidism, Pre-eclampsia with Severe Features, and Primary Aldosteronism

Background and Objectives: Graves' disease (GD) and primary aldosteronism (PA) are two pathologies that can cause significant morbidity and mortality. GD is mediated by autoantibodies, and recent studies have shown autoantibody involvement in the pathophysiology behind both PA and pre-eclampsia. The coexistence of GD and PA, however, is reportedly rare. This report describes a unique case of Graves' hyperthyroidism and concomitant PA in a patient with a history of pre-eclampsia with severe features. Case Presentation: The patient presented at 17 weeks pregnancy with mild hyperthyroidism, negative TSH receptor antibodies, and a low level of thyroid-stimulating immunoglobulins (TSI). Her TSH became detectable with normal thyroid hormone levels, and therefore, no anti-thyroid medication was administered. At 34 weeks she developed pre-eclampsia with severe features, and a healthy child was delivered; her TSH returned to normal. Seven months after delivery, she presented emergently with severe hyperthyroidism, hypertensive crisis, and a serum potassium of 2.5 mmol/L. Her hypertension was uncontrolled on multiple anti-hypertensives. Both TSI and TSH receptor antibodies were negative. The aldosterone(ng/dL)/renin(ng/mL/h ratio was (13/0.06) = 216.7, and abdominal CT imaging demonstrated normal adrenal glands; thus, a diagnosis of PA was made. Her blood pressure was subsequently controlled with only spironolactone at 50 mg 2xday. Methimazole was started but discontinued because of an allergic reaction. Consequently, a thyroidectomy was performed, and pathology revealed Graves' disease. The patient remained well on levothyroxine at 125 mcg/day and spironolactone at 50 mg 2xday three months after the thyroidectomy. Conclusions: This patient manifested severe GD with antibodies undetectable by conventional TSI and TSH receptor assays and accelerated hypertension from PA simultaneously. These conditions were successfully treated separately by spironolactone and thyroidectomy. Autoimmune PA was considered likely given the clinical picture. The diagnosis of PA should be considered in hypertension with GD.

[Immunogenetics of primary hyperaldosteronism: fundamental studies and their clinical prospects]

Primary hyperaldosteronism (PHA) is the most common form of endocrine hypertension. Until recently, the reason for the development of this condition was believed to be the presence of genetic mutations, however, many studies declare that the disease can be polyetiologic, be the result of genetic mutations and autoimmune triggers or cell clusters of aldosterone-producing cells diffusely located in the adrenal gland at the zona glonerulosa, zona fasculata, zona reticularis, as well as directly under the adrenal capsule. Recently, the actions of autoantibodies to type 1 angiotensin II receptors have been described in patients with renal transplant rejection, with preeclampsia, and with primary hyperaldosteronism. The diagnostic role of antibodies in both forms of PHA (aldosterone-producing adenoma and bilateral hyperaldosteronism) requires clarification. Diagnosis and confirmation of the focus of aldosterone hypersecretion is a multi-stage procedure that requires a long time and economic costs. The relevance of timely diagnosis of primary hyperaldosteronism is to reduce medical and social losses. This work summarizes the knowledge about genetic mutations and presents all the original studies devoted to autoantibodies in PHA, as well as discusses the diagnostic capabilities and limitations of the available methods of primary and differential diagnosis of the disease and the prospects for therapy.

Progress on Genetic Basis of Primary Aldosteronism

Primary aldosteronism (PA) is a heterogeneous group of disorders caused by the autonomous overproduction of aldosterone with simultaneous suppression of plasma renin activity (PRA). It is considered to be the most common endocrine cause of secondary arterial hypertension (HT) and is associated with a high rate of cardiovascular complications. PA is most often caused by a bilateral adrenal hyperplasia (BAH) or aldosterone-producing adenoma (APA); rarer causes of PA include genetic disorders of steroidogenesis (familial hyperaldosteronism (FA) type I, II, III and IV), aldosterone-producing adrenocortical carcinoma, and ectopic aldosterone-producing tumors. Over the last few years, significant progress has been made towards understanding the genetic basis of PA, classifying it as a channelopathy. Recently, a growing body of clinical evidence suggests that mutations in ion channels appear to be the major cause of aldosterone-producing adenomas, and several mutations within the ion channel encoding genes have been identified. Somatic mutations in four genes (KCNJ5, ATP1A1, ATP2B3 and CACNA1D) have been identified in nearly 60% of the sporadic APAs, while germline mutations in KCNJ5 and CACNA1H have been reported in different subtypes of familial hyperaldosteronism. These new insights into the molecular mechanisms underlying PA may be associated with potential implications for diagnosis and therapy.

Higher prevalence of metabolic disorders in patients with bilateral primary aldosteronism than unilateral primary aldosteronism

OBJECTIVE

Metabolic syndrome (MetS) is a frequent clinical condition in hypertension patients and is more frequently reported in primary aldosteronism (PA). This study is aimed at investigating the prevalence of MetS and its components in the two major types of patients with adrenal venous sampling (AVS)-confirmed unilateral PA and bilateral PA.

DESIGN AND PATIENTS

This was a retrospective cross-section study. We analysed metabolic parameters from 169 PA patients subtyped by AVS, including 85 unilateral PA patients and 84 bilateral PA patients, and we also included 169 non-PA patients matched for age and sex.

RESULTS

Patients with unilateral PA had higher concentrations of aldosterone and lower serum potassium than patients with bilateral PA. However, patients with bilateral PA had higher prevalence of MetS (79.8% vs 64.7%, P = .029), obesity (40.5% vs 24.7%, P = .029), dyslipidemia (72.6% vs 55.3%, P = .019) and hyperglycaemia (29.8% vs 16.5%, P = .040) than those with unilateral PA. Meanwhile, bilateral PA had higher BMI (27.55 ± 4.58 vs 25.57 ± 3.28 kg/m² , P = .001), waist circumference (98.54 ± 11.44 vs 93.32 ± 10.64 cm, P = .003) and fasting plasma glucose (4.98 ± 1.16 vs 4.64 ± 0.93 mmol/L, P = .034). The logistic regression analysis also showed that bilateral PA was associated with the presence of MetS after adjustment for age, sex and duration of hypertension.

CONCLUSIONS

Patients with bilateral PA have a higher prevalence of MetS than those with unilateral PA, despite unilateral PA patients exhibiting higher concentrations of aldosterone and lower serum potassium, suggesting that unilateral PA and bilateral PA may have differing mechanisms of MetS.

Common innate pathways to autoimmune disease

Until recently, autoimmune disease research has primarily been focused on elucidating the role of the adaptive immune system. In the past decade or so, the role of the innate immune system in the pathogenesis of autoimmunity has increasingly been realized. Recent findings have elucidated paradigm-shifting concepts, for example, the implications of "trained immunity" and a dysbiotic microbiome in the susceptibility of predisposed individuals to clinical autoimmunity. In addition, the application of modern technologies such as the quantum dot (Qdot) system and 'Omics' (e.g., genomics, proteomics, and metabolomics) data-processing tools has proven fruitful in revisiting mechanisms underlying autoimmune pathogenesis and in identifying novel therapeutic targets. This review highlights recent findings discussed at the American Autoimmune Related Disease Association (AARDA) 2019 colloquium. The findings covering autoimmune diseases and autoinflammatory diseases illustrate how new developments in common innate immune pathways can contribute to the better understanding and management of these immune-mediated disorders.

Diverse Responses of Autoantibodies to the Angiotensin II Type 1 Receptor in Primary Aldosteronism

Primary aldosteronism is a common form of endocrine hypertension mainly caused by a unilateral aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia (BAH). AT1R-Abs (autoantibodies to the angiotensin II type 1 receptor) have been reported in patients with disorders associated with hypertension. Our objective was to assess AT1R-Ab levels in patients with primary aldosteronism (APA, n=40 and BAH, n=40) relative to patients with primary hypertension (n=40), preeclampsia (n=23), and normotensive individuals (n=25). AT1R-Abs in whole sera were measured using 2 different ELISAs which gave contrasting results. A functional cell-based assay was used to quantify activation of the AT1R (angiotensin II type 1 receptor) using whole sera or affinity-purified antibodies in the absence or presence of losartan (a specific AT1R antagonist). Serum samples from all groups displayed different levels of AT1R activation with different responses to losartan. Patients with BAH displayed higher losartan-independent affinity-isolated agonistic AT1R-Ab levels compared with patients with APA (P<0.01) and with normotensive individuals (P<0.0001). In patients with APA, BAH, and primary hypertension combined, higher aldosterone-to-renin ratios and lower plasma renin concentrations were associated with higher compared with lower agonistic AT1R-Ab levels. In patients with primary aldosteronism, higher AT1R-Ab activity was associated with an increased likelihood of a diagnosis of BAH compared with APA and with the presence of adrenal hyperplasia detected by computed tomography. Taken together, these data suggest that agonistic AT1R-Abs may have a functional role in a subgroup of patients with primary aldosteronism.

Coexistence of Primary Hyperaldosteronism and Graves' Disease, a Rare Combination of Endocrine Disorders: Is It beyond a Coincidence-A Case Report and Review of the Literature

BACKGROUND

Primary hyperaldosteronism is a known cause for secondary hypertension. In addition to its effect on blood pressure, aldosterone exhibits proinflammatory actions and plays a role in immunomodulation/development of autoimmunity. Recent researches also suggest significant thyroid dysfunction among patients with hyperaldosteronism, but exact causal relationship is not established. Autoimmune hyperthyroidism (Graves' disease) and primary hyperaldosteronism rarely coexist but underlying mechanisms associating the two are still unclear.

CASE PRESENTATION

A 32-year-old Sri Lankan female was evaluated for new onset hypertension in association with hypokalemia. She also had features of hyperthyroidism together with high TSH receptor antibodies suggestive of Graves' disease. On evaluation of persistent hypokalemia and hypertension, primary hyperaldosteronism due to right-sided adrenal adenoma was diagnosed. She was rendered euthyroid with antithyroid drugs followed by right-sided adrenalectomy. Antithyroid drugs were continued up to 12 months, after which the patient entered remission of Graves' disease.

CONCLUSION

Autoimmune hyperthyroidism and primary hyperaldosteronism rarely coexist and this case report adds to the limited number of cases documented in the literature. Underlying mechanism associating the two is still unclear but possibilities of autoimmune mechanisms and autoantibodies warrant further evaluation and research.