Gene Expression to Guide Glucocorticoid Replacement in Autoimmune Addison’s Disease

Objective: Deciding the optimal doses of glucocorticoid (GC) replacement treatment in autoimmune Addison’s disease (AAD) is impeded by the lack of reliable biomarkers. This frequently results in over-treatment, with alarming and persistent side-effects, or under-replacement, which could be fatal. There is a need to think new in the quest for robust biomarkers to optimize GC replacement in AAD at an individual level. Aim: We aimed to identify genes that are consistently up- or down-regulated in patients with AAD in response to different GC replacement doses. This information can be used to establish novel biomarkers to guide GC treatment in AAD. Methods: Step 1: Global microarray expression analysis on RNA from whole blood before and after intravenous infusion of 100 mg hydrocortisone (HC) in 10 patients with AAD. To verify the results, we performed real-time PCR to compare gene expression levels of three of the highly differentially expressed genes (FKBP5, MMP9, and DSIPI) to compare gene expression levels before and two, four, and six hours after the HC infusion. Step 2: Rt-PCR to compare expression levels of 93 GC-regulated genes in normal versus very low morning cortisol levels in 27 patients with AAD. Results: Step 1: Two hours after infusion of 100 mg HC, there was a marked increase in FKBP5, MMP9, and DSIPI expression levels. MMP9 and DSIPI expression levels correlated with serum cortisol. Step 2: Expression levels of CEBPB, DDIT4, FKBP5, DSIPI, and VDR were increased and ADARB1, ARIDB5, and POU2F1 decreased in normal versus very low morning cortisol. Normal serum cortisol levels positively correlated with DSIPI, DDIT4, and FKBP5 expression. Conclusions: We introduce gene expression as a novel approach to guide GC replacement in AAD. We suggest that gene expression of DSIPI, DDIT4, and FKBP5 are particularly promising candidate biomarkers of GC replacement, followed by MMP9, CEBPB, VDR, ADARB1, ARID5B, and POU2F1.