Endocrine Abstracts

Background: Glucocorticoid (GC) substitution therapy in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) is not able to perfectly mimic physiological circadian profiles. Unphysiologically high doses, as well as unphysiological variations in GC concentrations might cause adverSemetabolic, cardiovascular and immunological effects. Previous publications have demonstrated dysregulations in immune cell profiles of patients with primary adrenal insufficiency (PAI) under standard hydrocortisone (HC) therapy most likely via dysregulations of clock gene expression. GCs have been shown to modulate expression of certain clock genes and are involved in creating a stable 24-hour rhythm of various cell types and physiological pathways. Thus, changes in GC profiles might differentially affect cell functions.

Methods: Cross-sectional single-center study including 75 patients with CAH and 50 sex- and BMI- matched healthy controls. Patients were divided into three groups depending on type of glucocorticoid medication: HC (n=28), prednisone/prednisolone (n=33) and modified-release hydrocortisone treatment (MR-HC n=14). Peripheral blood mononuclear cells (PBMCs) were isolated from all subjects using a Ficoll density gradient centrifugation within 4 hours after sample collection. Real-time qPCR was carried out for expression of the following nine clock genes (CLOCK, ARNTL, CRY1, CRY2, NR1D1, WEE1, TIMELESS, CREB1, PER3).

Results: CLOCK gene mRNA expression was reduced in CLOCK (P<0.0001), CRY1 (P<0.0001), and TIMELESS (P<0.0001) in patients versus controls regardless of type of GC medication used. WEE1 and CRY2 mRNA expression were only reduced in patients using conventional GCs as HC (WEE1 P=0.0018, CRY2 P=0.0002) and prednisone/prednisolone (WEE1 P<0.0001, CRY2 P=0.0001). Compared to controls, ARNTL mRNA expression was only reduced in patients treated with prednisone/prednisolone (P=0.0436). There was no change in NR1D1, CREB1 or PER3 expression between the different treatment groups and controls. Least changes in mRNA expression compared to healthy controls were observed in patients treated with MR-HC (CLOCK P=0.0001, TIMELESS P=0.0003, WEE1 P=0.7960, CRY2 P=0.1119).

Conclusion: CAH patients receiving conventional therapy exhibit dysregulations of CLOCK gene expression in PBMCs. Least disturbance of CLOCK gene mRNA expression compared to healthy controls was observed in those patients treated with MR-HC preparations. Further studies are needed to explicitly analyze these effects in CLOCK gene expression on the clinical phenotype including adverSemetabolic, cardiovascular and immunological events.