Peripheral Blood Cells from Patients with Autoimmune Addison's Disease Poorly Respond to Interferons In Vitro, Despite Elevated Serum Levels of Interferon-Inducible Chemokines.

Autoimmune Addison's disease (AAD) is a disorder caused by an immunological attack on the adrenal cortex. The interferon (IFN)-inducible chemokine CXCL10 is elevated in serum of AAD patients, suggesting a peripheral IFN signature. However, CXCL10 can also be induced in adrenocortical cells stimulated with IFNs, cytokines, or microbial components. We therefore investigated whether peripheral blood mononuclear cells (PBMCs) from AAD patients display an enhanced propensity to produce CXCL10 and the related chemokine CXCL9, after stimulation with type I or II IFNs or the IFN inducer poly (I:C). Although serum levels of CXCL10 and CXCL9 were significantly elevated in patients compared with controls, IFN stimulated patient PBMC produced significantly less CXCL10/CXCL9 than control PBMC. Low CXCL10 production was not significantly associated with medication, disease duration, or comorbidities, but the low production of poly (I:C)-induced CXCL10 among patients was associated with an AAD risk allele in the phosphatase nonreceptor type 22 (PTPN22) gene. PBMC levels of total STAT1 and -2, and IFN-induced phosphorylated STAT1 and -2, were not significantly different between patients and controls. We conclude that PBMC from patients with AAD are deficient in their response to IFNs, and that the adrenal cortex itself may be responsible for the increased serum levels of CXCL10.

Altered DNA methylation profile in Norwegian patients with Autoimmune Addison's Disease.

Autoimmune Addison's Disease (AAD) is an endocrine and immunological disease of uncertain pathogenesis resulting from the immune system's destruction of the hormone producing cells of the adrenal cortex. The underlying molecular mechanisms are largely unknown, but it is commonly accepted that a combination of genetic susceptibility and environmental impact is critical. In the present study, we identified multiple hypomethylated gene promoter regions in patients with isolated AAD using DNA isolated from CD4+ T cells. The identified differentially methylated regions were distributed evenly across the 10.5-kb-promoter regions covered by the array, and a substantial number localized to promoters of genes involved in immune regulation and autoimmunity. This study reveals a hypomethylated status in CD4+ T cells from AAD patients and indicates differential methylation of promoters of key genes involved in immune responses.

Epigenetic regulation of the gene encoding steroidogenic factor-1.

The nuclear receptor steroidogenic factor 1 (SF-1) is expressed in a precise time and cell-specific pattern in the endocrine system. Three intronic enhancers and one upstream enhancer, which are required for controlling the restricted expression of SF-1, have been identified in the mouse gene encoding SF-1. In recent years, efforts from several laboratories have established that expression of SF-1 is controlled by DNA methylation. CpG-sites are found in the basal promoter as well as in the intronic enhancers, and the methylation status of these genomic regions nearly perfectly correlates with their transcriptional activity such that they are hypomethylated in tissues where they are active, and generally hypermethylated in tissues where they are not active. This review summarizes the present knowledge of how tissue differentially methylated regions control the transcriptional activity of the SF-1 gene, and how irregularities in the methylation pattern can contribute to disease development.

DNA methylation of intronic enhancers directs tissue-specific expression of steroidogenic factor 1/adrenal 4 binding protein (SF-1/Ad4BP).

The nuclear receptor steroidogenic factor 1/adrenal 4 binding protein (SF-1/Ad4BP) is an essential regulator of endocrine development and function, and the expression of the corresponding gene (sf-1/ad4bp) is precisely regulated in a time- and tissue-dependent manner. We previously demonstrated that the basal promoter of sf-1/ad4bp is controlled by DNA methylation and that its methylation status reflects the expression pattern of SF-1/Ad4BP. Recently, three intronic enhancers were identified in the sf-1/ad4bp gene that target SF-1/Ad4BP expression to the fetal adrenal (FAdE; fetal adrenal-specific enhancer), to pituitary gonadotropes (PGE; pituitary gonadotrope-specific enhancer), and to the ventromedial hypothalamic nucleus (VMHE; ventromedial hypothalamic nucleus-specific enhancer). Here, we demonstrate that the activity of these enhancers is correlated with their DNA methylation status. We show that they are hypomethylated in tissues where they are active and generally hypermethylated in tissues where they are not active. Furthermore, we demonstrate in transient transfection experiments that forced DNA methylation represses reporter gene activity driven by these enhancers. These data directly demonstrate a functional significance for the enhancers' methylation status. Intriguingly, further analyses of the basal promoter in gonadotropes revealed that it is methylated in these cells, in contrast to other SF-1/Ad4BP-expressing tissues. Consistent with this, sf-1/ad4bp is transcribed from an alternative promoter in gonadotropes. Taken together, our experiments show that the tissue-specific expression of SF-1/Ad4BP is epigenetically regulated and identify tissue-specific differentially methylated regions within the sf-1/ad4bp locus that are essential for its transcriptional control.