Autoimmune primary adrenal insufficiency -current diagnostic approaches and future perspectives

The adrenal glands are small endocrine glands located on top of each kidney, producing hormones regulating important functions in our body like metabolism and stress. There are several underlying causes for adrenal insufficiency, where an autoimmune attack by the immune system is the most common cause. A number of genes are known to confer early onset adrenal disease in monogenic inheritance patterns, usually genetic encoding enzymes of adrenal steroidogenesis. Autoimmune primary adrenal insufficiency is usually a polygenic disease where our information recently has increased due to genome association studies. In this review, we go through the physiology of the adrenals before explaining the different reasons for adrenal insufficiency with a particular focus on autoimmune primary adrenal insufficiency. We will give a clinical overview including diagnosis and current treatment, before giving an overview of the genetic causes including monogenetic reasons for adrenal insufficiency and the polygenic background and inheritance pattern in autoimmune adrenal insufficiency. We will then look at the autoimmune mechanisms underlying autoimmune adrenal insufficiency and how autoantibodies are important for diagnosis. We end with a discussion on how to move the field forward emphasizing on the clinical workup, early identification, and potential targeted treatment of autoimmune PAI

B cells and autoantibodies in AIRE deficiency

Autoimmune polyendocrine syndrome type 1 (APS-1) is a rare but severe monogenetic autoimmune endocrine disease caused by failure of the Autoimmune Regulator (AIRE). AIRE regulates the negative selection of T cells in the thymus, and the main pathogenic mechanisms are believed to be T cell-mediated, but little is known about the role of B cells. Here, we give an overview of the role of B cells in thymic and peripheral tolerance in APS-1 patients and different AIRE-deficient mouse models. We also look closely into which autoantibodies have been described for this disorder, and their implications. Based on what is known about B cell therapy in other autoimmune disorders, we outline the potential of B cell therapies in APS-1 and highlight the unresolved research questions to be answered.publishedVersio

Interferon autoantibodies as signals of a sick thymus

Type I interferons (IFN-I) are key immune messenger molecules that play an important role in viral defense. They act as a bridge between microbe sensing, immune function magnitude, and adaptive immunity to fight infections, and they must therefore be tightly regulated. It has become increasingly evident that thymic irregularities and mutations in immune genes affecting thymic tolerance can lead to the production of IFN-I autoantibodies (autoAbs). Whether these biomarkers affect the immune system or tissue integrity of the host is still controversial, but new data show that IFN-I autoAbs may increase susceptibility to severe disease caused by certain viruses, including SARS-CoV-2, herpes zoster, and varicella pneumonia. In this article, we will elaborate on disorders that have been identified with IFN-I autoAbs, discuss models of how tolerance to IFN-Is is lost, and explain the consequences for the host

Systemic interferon type I and B cell responses are impaired in autoimmune polyendocrine syndrome type 1

Autoimmune polyendocrine syndrome type I (APS-1) is caused by mutations in the autoimmune regulator (AIRE) gene and characterised clinically by multiple autoimmune manifestations and serologically by autoantibodies against tissue proteins and cytokines. We here hypothesised that lack of AIRE expression in thymus affects blood immune cells and performed whole-blood microarray analysis (N = 16 APS-I patients vs 16 controls), qPCR verification, and bioinformatic deconvolution of cell subsets. We identified B cell responses as being downregulated in APS-1 patients, which was confirmed by qPCR; these results call for further studies on B cells in this disorder. The type I interferon (IFN-I) pathway was also downregulated in APS-1, and the presence of IFN antibodies is the likely reason for this mild overall downregulation of the IFN-I genes in most APS-1 patients.publishedVersio

Transcriptional Changes in Regulatory T Cells From Patients With Autoimmune Polyendocrine Syndrome Type 1 Suggest Functional Impairment of Lipid Metabolism and Gut Homing

Autoimmune polyendocrine syndrome type I (APS-1) is a monogenic model disorder of organ-specific autoimmunity caused by mutations in the Autoimmune regulator (AIRE) gene. AIRE facilitates the expression of organ-specific transcripts in the thymus, which is essential for efficient removal of dangerous self-reacting T cells and for inducing regulatory T cells (Tregs). Although reduced numbers and function of Tregs have been reported in APS-I patients, the impact of AIRE deficiency on gene expression in these cells is unknown. Here, we report for the first time on global transcriptional patterns of isolated Tregs from APS-1 patients compared to healthy subjects. Overall, we found few differences between the groups, although deviant expression was observed for the genes TMEM39B, SKIDA1, TLN2, GPR15, FASN, BCAR1, HLA-DQA1, HLA-DQB1, HLA-DRA, GPSM3 and AKR1C3. Of significant interest, the consistent downregulation of GPR15 may indicate failure of Treg gut homing which could be of relevance for the gastrointestinal manifestations commonly seen in APS-1. Upregulated FASN expression in APS-1 Tregs points to increased metabolic activity suggesting a putative link to faulty Treg function. Functional studies are needed to determine the significance of these findings for the immunopathogenesis of APS-1 and for Treg immunobiology in general.publishedVersio

21-Hydroxylase-Specific CD8+ T Cells in Autoimmune Addison’s Disease Are Restricted by HLA-A2 and HLA-C7 Molecules

Objectives: CD8+ T cells targeting 21-hydroxylase (21OH) are presumed to play a central role in the destruction of adrenocortical cells in autoimmune Addison’s disease (AAD). Earlier reports have suggested two immunodominant CD8+ T cell epitopes within 21OH: LLNATIAEV (21OH342-350), restricted by HLA-A2, and EPLARLEL (21OH431-438), restricted by HLA-B8. We aimed to characterize polyclonal CD8+ T cell responses to the proposed epitopes in a larger patient cohort with AAD. Methods: Recombinant fluorescent HLA-peptide multimer reagents were used to quantify antigen-specific CD8+ T cells by flow cytometry. Interferon-gamma (IFNγ) Elispot and biochemical assays were used to functionally investigate the 21OH-specific T cells, and to map the exactly defined epitopes of 21OH. Results: We found a significantly higher frequency of HLA-A2 restricted LLNATIAEV-specific cells in patients with AAD than in controls. These cells could also be expanded in vitro in an antigen specific manner and displayed a robust antigen-specific IFNγ production. In contrast, only negligible frequencies of EPLARLEL-specific T cells were detected in both patients and controls with limited IFNγ response. However, significant IFNγ production was observed in response to a longer peptide encompassing EPLARLEL, 21OH430-447, suggesting alternative dominant epitopes. Accordingly, we discovered that the slightly offset ARLELFVVL (21OH434-442) peptide is a novel dominant epitope restricted by HLA-C7 and not by HLA-B8 as initially postulated. Conclusion: We have identified two dominant 21OH epitopes targeted by CD8+ T cells in AAD, restricted by HLA-A2 and HLA-C7, respectively. To our knowledge, this is the first HLA-C7 restricted epitope described for an autoimmune disease.publishedVersio

Systemic Activation of the Kynurenine Pathway in Graves Disease With and Without Ophthalmopathy

Context Graves disease (GD) is one of the most common autoimmune disorders. Recent literature has shown an immune response involving several different inflammatory related proteins in these patients. Objective This work aimed to characterize the kynurenine pathway, activated during interferon-γ (IFN-γ)–mediated inflammation and cellular (T-helper type 1 [Th1] type) immunity, in GD patients with and without thyroid eye disease (TED). Methods We analyzed 34 biomarkers by mass spectrometry in serum samples from 100 patients with GD (36 with TED) and 100 matched healthy controls. The analytes included 10 metabolites and 3 indices from the kynurenine pathway, 6 microbiota-derived metabolites, 10 B-vitamers, and 5 serum proteins reflecting inflammation and kidney function. Results GD patients showed significantly elevated levels of 7 biomarkers compared with healthy controls (omega squared [ω2] > 0.06; P < .01). Of these 7, the 6 biomarkers with the strongest effect size were all components of the kynurenine pathway. Factor analysis showed that biomarkers related to cellular immunity and the Th1 responses (3-hydroxykynurenine, kynurenine, and quinolinic acid with the highest loading) were most strongly associated with GD. Further, a factor mainly reflecting acute phase response (C-reactive protein and serum amyloid A) showed weaker association with GD by factor analysis. There were no differences in biomarker levels between GD patients with and without TED. Conclusion This study supports activation of IFN-γ inflammation and Th1 cellular immunity in GD, but also a contribution of acute-phase reactants. Our finding of no difference in systemic activation of the kynurenine pathway in GD patients with and without TED implies that the local Th1 immune response in the orbit is not reflected systemically.publishedVersio

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

A longitudinal follow-up of autoimmune polyendocrine syndrome type 1

Source:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4971337/Context: Autoimmune polyendocrine syndrome type 1 (APS1) is a childhood-onset monogenic disease defined by the presence of two of the three major components: hypoparathyroidism, primary adrenocortical insuffi- ciency, and chronic mucocutaneous candidiasis (CMC). Information on longitudinal follow-up of APS1 is sparse. Objective: To describe the phenotypes of APS1 and correlate the clinical features with autoantibody profiles and autoimmune regulator ( AIRE) mutations during extended follow-up (1996–2016). Patients: All known Norwegian patients with APS1. Results: Fifty-two patients from 34 families were identified. The majority presented with one of the major disease components during childhood. Enamel hypoplasia, hypoparathyroidism, and CMC were the most frequent compo- nents.Withage,mostpatientspresentedthreetofivediseasemanifestations,althoughsomehadmilderphenotypes diagnosed in adulthood. Fifteen of the patients died during follow-up (median age at death, 34 years) or were deceasedsiblingswithahighprobabilityofundisclosedAPS1.Allexceptthreehadinterferon- )autoantibodies,and allhadorgan-specificautoantibodies.Themostcommon AIRE mutationwasc.967_979del13,foundinhomozygosity in 15 patients. A mild phenotype was associated with the splice mutation c.879 1G A. Primary adrenocortical insufficiency and type 1 diabetes were associated with protective human leucocyte antigen genotypes. Conclusions: Multiple presumable autoimmune manifestations, in particular hypoparathyroidism, CMC, and enamel hypoplasia, should prompt further diagnostic workup using autoantibody analyses (eg, interferon- ) and AIRE sequencing to reveal APS1, even in adults. Treatment is complicated, and mortality is high. Structured follow-up should be performed in a specialized center