GATA6, SF1, NGFIB and DAX1 in the remodeled subcapsular zones in primary aldosteronism.

The majority of the cases diagnosed as primary aldosteronism (PA) are caused by aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). Histopathologically, both IHA and adjacent adrenal glands of APA demonstrate remodeled subcapsular zone (RSZ) but these zones in two disorders are markedly different in terms of steroidogenesis. 3ß-Hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3ß-HSD) expression has been known to be activated synergistically by GATA6 and SF1, and repressed by DAX1 through abolishing the activation. Nerve growth factor-induced clone B (NGFIB) is also known as one of the transcription factors to bind to and activate 3ß-HSD promoter. The results of our immunohistochemical analysis demonstrated the expression levels of 3ß-HSD in RSZ of IHA were higher than in RSZ of adjacent adrenals of APA, while those in the zona glomerulosa (ZG) of normal adrenal gland (NA) were in between these two RSZs. The expression levels of GATA6, SF1 and DAX1 did not prominently differ among these three types of adrenals, especially between in RSZs of IHA and APA cases, indicating the marked difference of 3ß-HSD expression was unlikely to be explained by the levels of these three factors. However, the levels of NGFIB expression were significantly higher in RSZ of IHA than in RSZ of adjacent adrenals of APA and the ZG of NA (P<0.05), which may partly account for the expression levels of 3ß-HSD among the three groups of adrenals. These results may imply NGFIB plays important roles in the marked differences in steroidogenic functions in the two distinct types of RSZ of PA cases.

Prolonged zona glomerulosa insufficiency causing hyperkalemia in primary aldosteronism after adrenalectomy.

CONTEXT: Unilateral adrenalectomy is the therapy of choice in aldosterone-producing adenoma (APA). Zona glomerulosa (ZG) insufficiency causing hyperkalemia after adrenalectomy has been described in case reports. OBJECTIVE: Our aim was to analyze the clinical relevance of ZG insufficiency causing hyperkalemia after adrenalectomy in a large series of patients with APA. DESIGN: This was a retrospective chart review. SETTING: The study was conducted at two tertiary university referral centers in Germany. PATIENTS: Data from 110 patients with confirmed APA adrenalectomized at the centers in Munich and Berlin between 2004 and 2012 were analyzed. MAIN OUTCOME MEASURES: The primary outcome was the incidence of ZG insufficiency causing hyperkalemia after adrenalectomy; the secondary outcome was the identification of risk factors predisposing for hyperkalemia. RESULTS: Eighteen of 110 patients (16%) developed postoperative hyperkalemia. The majority of these patients (n = 14) had undetectable plasma aldosterone levels after adrenalectomy; four had low aldosterone levels. In 12 of these patients, hyperkalemia was documented only once and resumed spontaneously. Prolonged hypoaldosteronism accompanied by hyperkalemia was observed in six patients (5% of total cohort). These patients needed continuous mineralocorticoid replacement therapy for 11-46 months. Mineralocorticoid antagonist treatment for 4 wk prior to surgery did not prevent hyperkalemia. In multivariate analysis, preoperatively decreased glomerular filtration rate and increased serum creatinine as well as increased postoperative creatinine and microalbuminuria remained significant predictors of hyperkalemia. CONCLUSION: Persistent postoperative hypoaldosteronism with hyperkalemia occurs in 5% of adrenalectomized PA patients through prolonged ZG insufficiency, requiring long-term fludrocortisone treatment. Potassium levels after adrenalectomy must be monitored to avoid life-threatening hyperkalemia.

Zone-specific cell proliferation during compensatory adrenal growth in rats.

Compensatory adrenal growth after unilateral adrenalectomy (ULA) leads to adrenocortical hyperplasia. Because zonal growth contributions are not clear, we characterized the phenotype of cortical cells that proliferate using immunofluorescence histochemistry and zone-specific cell counting. Rats underwent ULA, sham adrenalectomy (sham), or no surgery and were killed at 2 or 5 days. Adrenals were weighed and sections immunostained for Ki67 (proliferation), cytochrome P-450 aldosterone synthase (P450aldo, glomerulosa), and cytochrome P-450 11beta-hydroxylase (P45011beta, fasciculata). Unbiased stereology was used to count proliferating glomerulosa and fasciculata cells. Adrenal weight increased after ULA compared with sham and no surgery at both time points, and there was no difference between sham and no surgery. However, either ULA or sham increased Ki67-positive cells in the outer fasciculata at both time points compared with no surgery. Outer fasciculata-restricted proliferation is thus associated with adrenal weight gain in ULA but not sham. Experiment repetition using proliferating cell nuclear antigen and bromodeoxyuridine showed similar results. After ULA, adrenal DNA, RNA, and protein increased at both time points, whereas after sham, only adrenal DNA increased at 2 days. Compensatory growth thus results from hyperplasia and hypertrophy, whereas sham induces only a transient adrenal hyperplasia. Dexamethasone pretreatment prevented the increase in adrenal weight after ULA and blocked Ki67 labeling in the outer fasciculata but not zona glomerulosa in all groups. These results clearly show that the outer fasciculata is the primary adrenal zone responsible for compensatory growth, responding to steroid-suppressible stress signals that alone are ineffective in increasing adrenal mass.

Changes in the glomerulosa cell phenotype during adrenal regeneration in rats.

In situ hybridization was used to examine cellular differentiation during rat adrenal regeneration, defining zona glomerulosa [cytochrome P-450 aldosterone synthase (P-450aldo) mRNA positive], zona fasciculata [cytochrome P-450 11beta-hydroxylase (P-45011beta) mRNA positive], or zona intermedia [negative for both but 3beta-hydroxysteroid dehydrogenase (3beta-HSD) mRNA positive]. After unilateral adrenal enucleation with contralateral adrenalectomy (ULE/ULA), the expression of all mRNA was reduced at 2 days. From 5 to 10 days, P-45011beta and 3beta-HSD mRNA increased while P-450aldo remained low; at 20 days, all mRNA were increased. From 2 to 10 days, cells adjacent to the capsule showed intermedia cell differentiation; by 20 days, the subcapsular glomerulosa cells reappeared. This suggests that after enucleation the glomerulosa dedifferentiates to zona intermedia. The experiment was repeated in rats where the postenucleation ACTH rise was prevented. Rats underwent ULE with sham ULA (ULE/SULA) or ULE/SULA with ACTH treatment. Adrenals from ULE/SULA rats expressed increased P-450aldo mRNA at 10 days and reduced P-45011beta mRNA and adrenal weight at 30 days. ACTH treatment reversed the pattern toward that seen in ULE/ULA. These findings show that the enucleation-induced dedifferentitation of the glomerulosa cell may result in part from elevated plasma ACTH and that prevention of dedifferentiation may result in impaired regeneration.