High frequency of cytolytic 21-hydroxylase-specific CD8+ T cells in autoimmune Addison's disease patients.

The mechanisms behind destruction of the adrenal glands in autoimmune Addison's disease remain unclear. Autoantibodies against steroid 21-hydroxylase, an intracellular key enzyme of the adrenal cortex, are found in >90% of patients, but these autoantibodies are not thought to mediate the disease. In this article, we demonstrate highly frequent 21-hydroxylase-specific T cells detectable in 20 patients with Addison's disease. Using overlapping 18-aa peptides spanning the full length of 21-hydroxylase, we identified immunodominant CD8(+) and CD4(+) T cell responses in a large proportion of Addison's patients both ex vivo and after in vitro culture of PBLs ≤20 y after diagnosis. In a large proportion of patients, CD8(+) and CD4(+) 21-hydroxylase-specific T cells were very abundant and detectable in ex vivo assays. HLA class I tetramer-guided isolation of 21-hydroxylase-specific CD8(+) T cells showed their ability to lyse 21-hydroxylase-positive target cells, consistent with a potential mechanism for disease pathogenesis. These data indicate that strong CTL responses to 21-hydroxylase often occur in vivo, and that reactive CTLs have substantial proliferative and cytolytic potential. These results have implications for earlier diagnosis of adrenal failure and ultimately a potential target for therapeutic intervention and induction of immunity against adrenal cortex cancer.

Cytokine Autoantibody Screening in the Swedish Addison Registry Identifies Patients With Undiagnosed APS1.

Context: Autoimmune polyendocrine syndrome type 1 (APS1) is a monogenic disorder that features autoimmune Addison disease as a major component. Although APS1 accounts for only a small fraction of all patients with Addison disease, early identification of these individuals is vital to prevent the potentially lethal complications of APS1. Objective: To determine whether available serological and genetic markers are valuable screening tools for the identification of APS1 among patients diagnosed with Addison disease. Design: We systematically screened 677 patients with Addison disease enrolled in the Swedish Addison Registry for autoantibodies against interleukin-22 and interferon-α4. Autoantibody-positive patients were investigated for clinical manifestations of APS1, additional APS1-specific autoantibodies, and DNA sequence and copy number variations of AIRE. Results: In total, 17 patients (2.5%) displayed autoantibodies against interleukin-22 and/or interferon-α4, of which nine were known APS1 cases. Four patients previously undiagnosed with APS1 fulfilled clinical, genetic, and serological criteria. Hence, we identified four patients with undiagnosed APS1 with this screening procedure. Conclusion: We propose that patients with Addison disease should be routinely screened for cytokine autoantibodies. Clinical or serological support for APS1 should warrant DNA sequencing and copy number analysis of AIRE to enable early diagnosis and prevention of lethal complications.

Common genetic variation in the autoimmune regulator (AIRE) locus is associated with autoimmune Addison's disease in Sweden.

Autoimmune Addison's disease (AAD) is the predominating cause of primary adrenal failure. Despite its high heritability, the rarity of disease has long made candidate-gene studies the only feasible methodology for genetic studies. Here we conducted a comprehensive reinvestigation of suggested AAD risk loci and more than 1800 candidate genes with associated regulatory elements in 479 patients with AAD and 2394 controls. Our analysis enabled us to replicate many risk variants, but several other previously suggested risk variants failed confirmation. By exploring the full set of 1800 candidate genes, we further identified common variation in the autoimmune regulator (AIRE) as a novel risk locus associated to sporadic AAD in our study. Our findings not only confirm that multiple loci are associated with disease risk, but also show to what extent the multiple risk loci jointly associate to AAD. In total, risk loci discovered to date only explain about 7% of variance in liability to AAD in our study population.

Identification of endothelin-converting enzyme-2 as an autoantigen in autoimmune polyendocrine syndrome type 1.

Autoimmune polyendocrine syndrome type 1 (APS1) is a rare monogenic autoimmune disorder caused by mutations in the autoimmune regulator (AIRE) gene. High titer autoantibodies are a characteristic feature of APS1 and are often associated with particular disease manifestations. Pituitary deficits are reported in up to 7% of all APS1 patients, with immunoreactivity to pituitary tissue frequently reported. We aimed to isolate and identify specific pituitary autoantigens in patients with APS1. Immunoscreening of a pituitary cDNA expression library identified endothelin-converting enzyme (ECE)-2 as a potential candidate autoantigen. Immunoreactivity against ECE-2 was detected in 46% APS1 patient sera, with no immunoreactivity detectable in patients with other autoimmune disorders or healthy controls. Quantitative-PCR showed ECE-2 mRNA to be most abundantly expressed in the pancreas with high levels also in the pituitary and brain. In the pancreas ECE-2 was co-expressed with insulin or somatostatin, but not glucagon and was widely expressed in GH producing cells in the guinea pig pituitary. The correlation between immunoreactivity against ECE-2 and the major recognized clinical phenotypes of APS1 including hypopituitarism was not apparent. Our results identify ECE-2 as a specific autoantigen in APS1 with a restricted neuroendocrine distribution.

Clinical and Immunological Characteristics of Autoimmune Addison Disease: A Nationwide Swedish Multicenter Study.

Context: Studies of the clinical and immunological features of autoimmune Addison disease (AAD) are needed to understand the disease burden and increased mortality. Objective: To provide upgraded data on autoimmune comorbidities, replacement therapy, autoantibody profiles, and cardiovascular risk factors. Design, Setting, and Participants: A cross-sectional, population-based study that included 660 AAD patients from the Swedish Addison Registry (2008-2014). When analyzing the cardiovascular risk factors, 3594 individuals from the population-based survey in Northern Sweden, MONICA (monitoring of trends and determinants of cardiovascular disease), served as controls. Main Outcome Measures: The endpoints were the prevalence of autoimmune comorbidities and cardiovascular risk factors. Autoantibodies against 13 autoantigens were determined. Results: The proportion of 21-hydroxylase autoantibody-positive patients was 83%, and 62% of patients had ≥1 associated autoimmune diseases, more frequently coexisting in females (P < 0.0001). AAD patients had a lower body mass index (P < 0.0001) and prevalence of hypertension (P = 0.027) compared with controls. Conventional hydrocortisone tablets were used by 89% of the patients, with a mean dose of 28.1 ± 8.5 mg/d. The mean hydrocortisone equivalent dose normalized to the body surface was 14.8 ± 4.4 mg/m2/d. A greater hydrocortisone equivalent dose was associated with a greater incidence of hypertension (P = 0.046). Conclusions: Careful monitoring of AAD patients is warranted to detect associated autoimmune diseases. Contemporary Swedish AAD patients did not have an increased prevalence of overweight, hypertension, type 2 diabetes mellitus, or hyperlipidemia. However, high glucocorticoid replacement doses could be a risk factor for hypertension.

Autoimmune polyendocrine syndrome type 1: Utility of KCNRG autoantibodies as a marker of active pulmonary disease and successful treatment with rituximab.

Autoimmune polyendocrine syndrome type 1 (APS-1), also known as Autoimmune Polyendocrinopathy Candidiasis and Ectodermal Dysplasia (APECD) is a disorder caused by mutations in the autoimmune regulator (AIRE) gene. In some APS-1 patients, significant pulmonary disease is observed. Autoantibodies directed against the potassium channel regulatory protein (KCNRG), found in epithelial cells of terminal bronchioles, have been suggested as a marker for pulmonary disease in APS-1 patients. We report two patients with APS-1; one with and one without lung disease. Patient 1 had multiple admissions for pneumonia and respiratory insufficiency, required non-invasive ventilation, and had findings of bronchiectasis on thoracic imaging and significant lymphocytic infiltrates of the airways on lung biopsy. To verify the autoimmune cause of pulmonary symptoms APS-1 patients, both were tested in a blinded manner for the presence of autoantibodies to KCNRG in serum. We found that only Patient 1 had autoantibodies present. Additionally, Patient 1 had progressive disease despite treatment with several immunomodulating agents, including corticosteroids, azathioprine, and mycophenolate. Patient 1 had a lung biopsy performed which was consistent with B cell lymphocytic aggregates. Rituximab treatment was initiated with apparent good response. This report illustrates the practical use of KCNRG autoantibodies to identify APS-1 patients with pulmonary risk and the successful use of the monoclonal antibody, Rituximab, to treat pulmonary disease in APS-1 patients.