Potential Transcriptional Biomarkers to Guide Glucocorticoid Replacement in Autoimmune Addison's Disease

Background No reliable biomarkers exist to guide glucocorticoid (GC) replacement treatment in autoimmune Addison’s disease (AAD), leading to overtreatment with alarming and persistent side effects or undertreatment, which could be fatal. Objective To explore changes in gene expression following different GC replacement doses as a means of identifying candidate transcriptional biomarkers to guide GC replacement 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. In 3 of the most highly upregulated genes, we performed real-time PCR (rt-PCR) to compare gene expression levels before and 3, 4, and 6 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 levels of 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.publishedVersio

Glucocorticoid pharmacogenetics in Addison's disease - The role of the immunophilin FK506-binding protein (FKBP51) for glucocorticoid sensitivity

There is great variation in the inter-individual sensitivity to glucocorticoids. The immunophilin FK506 binding protein (FKBP51) confers short-loop negative feedback inhibition of the glucocorticoid signalling pathway. FKBP51 keeps the human glucocorticoid receptor (hGR)-protein complex in a state of low hormone binding affinity, and will thus inhibit the effect of glucocorticoids. We investigated the role of FKBP51 for the variation in sensitivity to glucocorticoids in patients with primary adrenal insufficiency (Addison's disease). The specific aim of this study was to evaluate the association between the single nucleotide polymorphism (SNP) rs1360780 in the FKBP5 gene encoding FKBP51 and the individual glucocorticoid sensitivity in patients with Addison's disease. Seventeen patients with Addison's disease and 19 controls were genotyped using allelic discrimination assay. In morning blood samples, taken after 18 hours medication fast in the patients, glucocorticoid sensitivity in leukocytes was assessed in an in vitro cell proliferation assay; that is, stimulation with mitogenic lectin phytohemagglutinin (PHA), and incubation with various concentrations of dexamethasone. The FKBP5 expression and the FKBP51 protein levels in leukocytes was determined before and after intravenous infusion of 100 mg hydrocortisone to the patients; using real-time PCR and Western blot analysis respectively. The cell proliferation assay points to increased glucocorticoid sensitivity in Addison's patients associated with the rs1360780 variant T-allele (P=0.001). No such association was found for the controls. The FKBP5 expression, FKBP51 protein levels and ACTH and cortisol levels showed no genotype specific pattern in our study. Increased understanding of the inter-individual glucocorticoid sensitivity and the mechanisms behind may improve treatment with glucocorticoids and increase the knowledge about the pathogenesis of diseases related to glucocorticoid sensitivity, such as depression and metabolic syndrome. Further research is needed to establish the definitive role of FKBP51 and its isoforms, and the the association rs1360780 with glucocorticoid sensitivity