21-Hydroxylase epitopes are targeted by CD8 T cells in autoimmune Addison's disease

Endocrinology Service, CHU Sainte-Justine, Department of Pediatrics, Université de Montréal, H3T 1C5 Montréal, Canada.
Journal of Autoimmunity (Impact Factor: 8.41). 12/2010; 35(4):309-15. DOI: 10.1016/j.jaut.2010.07.001
Source: PubMed


In autoimmune adrenal deficiency, autoantibodies target the 21-hydroxylase (21OH) protein. However, it is presumed that autoreactive T cells, rather than antibodies, are the main effectors of adrenal gland destruction, but their identification is still lacking. We performed a T-cell epitope mapping study using 49 overlapping 20mer peptides covering the 21OH sequence in patients with isolated Addison's disease, Autoimmune Polyendocrine Syndrome 1 and 2. IFNγ ELISPOT responses against these peptides were stronger, broader and more prevalent among patients than in controls, whatever the disease presentation. Five peptides elicited T-cell responses in patients only (68% sensitivity, 100% specificity). Blocking experiments identified IFNγ-producing cells as CD8 T lymphocytes, with two peptides frequently recognized in HLA-B8+ patients and a third one targeted in HLA-B35+ subjects. In particular, the 21OH(431-450) peptide was highly immunodominant, as it was recognized in more than 30% of patients, all carrying the HLA-B8 restriction element. This 21OH(431-450) region contained an EPLARLEL octamer (21OH(431-438)) predicted to bind to HLA-B8 with high affinity. Indeed, circulating EPLARLEL-specific CD8 T cells were detected at significant frequencies in HLA-B8+ patients but not in controls by HLA tetramer staining. This report enlightens disease-specific T-cell biomarkers and epitopes targeted in autoimmune adrenal deficiency.

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    • "Both p38 and JNK pathways are therefore involved in the activation and differentiation of antigenspecific T cells, predominantly of the T H 1 type. It is presumable, therefore, that these pathways are involved in the development of disease-specific IFN␥ producing T cells recognizing CYP21 that have previously been demonstrated in AAD patients (Bratland et al., 2009; Rottembourg et al., 2010). Hypomethylated DMRs were identified in a considerable number of genes encoding members of the tumor necrosis factor (TNF) superfamily. "
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    ABSTRACT: 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.
    Full-text · Article · Jun 2014 · Molecular Immunology
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    • "Thus, in solitary AD and in APECED with adrenocortical failure, autoantibodies recognize the p450c21 steroidogenic enzyme. Interestingly, in this disease complex CD8 + T cells that reach against specific T cell epitopes in p450c21 has been demonstrated (Bratland et al., 2009; Rottembourg et al., 2010) Likewise, in thyroid diseases, thyroglobulin and thyroid peroxidase are recognized by the autoantibodies, irrespective if the condition is occurring alone, in association of APS-2 or as part of the APECED complex. The similar synergism in terms of the nature of autoantigens occurs in chronic immunological liver diseases, too. "
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    ABSTRACT: In APECED, the key abnormality is in the T cell defect that may lead to tissue destruction chiefly in endocrine organs. Besides, APECED is characterized by high-titer antibodies against a wide variety of cytokines that could partly be responsible for the clinical symptoms during APECED, mainly chronic mucocutaneous candidiasis, and linked to antibodies against Th17 cells effector molecules, IL-17 and IL-22. On the other hand, the same antibodies, together with antibodies against type I interferons may prevent the patients from other immunological diseases, such as psoriasis and systemic lupus erythematous. The same effector Th17 cells, present in the lymphocytic infiltrate of target organs of APECED, could be responsible for the tissue destruction. Here again, the antibodies against the corresponding effector molecules, anti-IL-17 and anti-IL-22 could be protective. The occurrence of several effector mechanisms (CD4(+) Th17 cell and CD8(+) CTL and the effector cytokines IL-17 and IL-22), and simultaneous existence of regulatory mechanisms (CD4(+) Treg and antibodies neutralizing the effect of the effector cytokines) may explain the polymorphism of APECED. Almost all the patients develop the characteristic manifestations of the complex, but temporal course and severity of the symptoms vary considerably, even among siblings. The autoantibody profile does not correlate with the clinical picture. One could speculate that a secondary homeostatic balance between the harmful effector mechanisms, and the favorable regulatory mechanisms, finally define both the extent and severity of the clinical condition in the AIRE defective individuals. The proposed hypothesis that in APECED, in addition to strong tissue destructive mechanisms, a controlling regulatory mechanism does exist, allow us to conclude that APECED could be treated, and even cured, with immunological manipulation.
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