MON-171 Characterization of the Adrenal Gland and Adrenal Rest Tissues in Congenital Adrenal Hyperplasia

Background: Adrenonodular hyperplasia and tumor formation are common long-term complications of congenital adrenal hyperplasia (CAH) driven by chronic ACTH elevation. Clinical studies indicate that the majority of males with classic CAH have testicular adrenal rest tumors (TART). Ovarian adrenal rest tumors (OART) are less commonly observed. Little is known about the pathophysiology of adrenal rest, however both adrenal cortex and Leydig cell markers have been described in TART, suggesting a pluripotent embryological cell origin. Objective: To characterize adrenals and adrenal rest tissues of patients with CAH in comparison with normal tissues. Materials and Methods: Using immunohistochemistry (IHC) and, real-time qRT-PCR we investigated CAH-affected adrenals (n=5), adrenal rest tissues (n=2; 1 testicular, 1 ovarian), controls [normal adrenal (n=2), testis (n=1), and ovary (n=1)]. Tissue sections prepared from paraffin embedded tissue blocks were immunostained with adrenal [melanocortin 2 receptor (MC2R), delta-like homolog 1 (DLK-1), steroidogenic factor 1 (SF-1), steroidogenic acute regulatory protein (StAR) and other cytochrome P450 genes], inflammatory [interleukin 2 receptor (IL-2R), B-lymphocyte antigen (CD20), cluster of differentiation 3 (CD3), tumor necrosis factor alpha (TNFα), interleukin 6 (IL6)], and gonadal markers [progesterone receptor (PR), androgen receptor (AR), insulin-like 3 (INSL3)]. RNA was isolated and gene expression studies were performed. High-throughput RNA sequencing technology was used to analyze the differential transcriptome profiles between the CAH adrenals, adrenal rest and normal tissues. Results: In contrast to the controls, CAH adrenals and adrenal rest tissues showed the following: (i) IHC studies revealed 95% of tissue positive for adrenal zona-reticularis; (ii) significant nodular lymphocytic infiltration with a predominance of B and T lymphocytes and overexpression of lymphocyte markers IL-2R, CD20, CD3, and inflammatory cytokines TNFα and IL6; (iii) increased expression of adrenocortical specific genes MC2R, DLK1. Conclusion: CAH-affected adrenals and adrenal rest tissue have similar predominance of zona reticularis and demonstrate lymphocytic infiltration. Active inflammation may play a role in the abnormal development of adrenal and adrenal rest tissue in CAH patients.