Cellular immunity and immunopathology in autoimmune Addison's disease

Rare copy number variation in autoimmune Addison's disease

Autoimmune Addison's disease (AAD) is a rare but life-threatening endocrine disorder caused by an autoimmune destruction of the adrenal cortex. A previous genome-wide association study (GWAS) has shown that common variants near immune-related genes, which mostly encode proteins participating in the immune response, affect the risk of developing this condition. However, little is known about the contribution of copy number variations (CNVs) to AAD susceptibility. We used the genome-wide genotyping data from Norwegian and Swedish individuals (1,182 cases and 3,810 controls) to investigate the putative role of CNVs in the AAD aetiology. Although the frequency of rare CNVs was similar between cases and controls, we observed that larger deletions (>1,000 kb) were more common among patients (OR = 4.23, 95% CI 1.85-9.66, p = 0.0002). Despite this, none of the large case-deletions were conclusively pathogenic, and the clinical presentation and an AAD-polygenic risk score were similar between cases with and without the large CNVs. Among deletions exclusive to individuals with AAD, we highlight two ultra-rare deletions in the genes LRBA and BCL2L11, which we speculate might have contributed to the polygenic risk in these carriers. In conclusion, rare CNVs do not appear to be a major cause of AAD but further studies are needed to ascertain the potential contribution of rare deletions to the polygenic load of AAD susceptibility.

Histopathological evaluation of the adrenal glands in a cat with primary hypoadrenocorticism and multiple endocrine disease

Case summary

A 6-year-old male neutered domestic longhair cat was referred for investigation of weight loss, hyporexia, vomiting and diarrhoea. The cat was diagnosed with primary hypoadrenocorticism, exocrine pancreatic insufficiency, cobalamin deficiency and a chronic enteropathy, and started on therapeutic treatment. Diabetes mellitus developed 4.5 months later, and the cat was started on insulin therapy. The cat was euthanased 10 months following the diagnosis of hypoadrenocorticism due to the development of status epilepticus, which was not associated with glucose or electrolyte abnormalities. Histopathological assessment of the adrenal glands at post-mortem examination documented lymphoplasmacytic adrenalitis, with the lymphocytic population being predominant. Immunohistochemical staining classified the lymphocytic infiltrate as T-cell rich, supportive of the cat's hypoadrenocorticism being due to autoimmune disease.

Relevance and novel information

This case documents the novel use of immunohistochemical staining in combination with histopathology to further assess the adrenal glands in non-neoplastic-associated primary hypoadrenocorticism in a cat. This identified similar pathological changes to those previously described in dogs with autoimmune primary hypoadrenocorticism. Additionally, this is the first report of a cat with multiple endocrine disease that included primary hypoadrenocorticism and highlights that monitoring for the development of additional endocrine disease should be advised in these cases.

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 (21OH_342-350), restricted by HLA-A2, and EPLARLEL (21OH_431-438), 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, 21OH_430-447, suggesting alternative dominant epitopes. Accordingly, we discovered that the slightly offset ARLELFVVL (21OH_434-442) 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.

Adrenal insufficiency

Adrenal insufficiency (AI) is a condition characterized by an absolute or relative deficiency of adrenal cortisol production. Primary AI (PAI) is rare and is caused by direct adrenal failure. Secondary AI (SAI) is more frequent and is caused by diseases affecting the pituitary, whereas in tertiary AI (TAI), the hypothalamus is affected. The most prevalent form is TAI owing to exogenous glucocorticoid use. Symptoms of AI are non-specific, often overlooked or misdiagnosed, and are related to the lack of cortisol, adrenal androgen precursors and aldosterone (especially in PAI). Diagnosis is based on measurement of the adrenal corticosteroid hormones, their regulatory peptide hormones and stimulation tests. The goal of therapy is to establish a hormone replacement regimen that closely mimics the physiological diurnal cortisol secretion pattern, tailored to the patient's daily needs. This Primer provides insights into the epidemiology, mechanisms and management of AI during pregnancy as well as challenges of long-term management. In addition, the importance of identifying life-threatening adrenal emergencies (acute AI and adrenal crisis) is highlighted and strategies for prevention, which include patient education, glucocorticoid emergency cards and injection kits, are described.

Translational Research in Vitiligo

Vitiligo is a disease of the skin characterized by the appearance of white spots. Significant progress has been made in understanding vitiligo pathogenesis over the past 30 years, but only through perseverance, collaboration, and open-minded discussion. Early hypotheses considered roles for innervation, microvascular anomalies, oxidative stress, defects in melanocyte adhesion, autoimmunity, somatic mosaicism, and genetics. Because theories about pathogenesis drive experimental design, focus, and even therapeutic approach, it is important to consider their impact on our current understanding about vitiligo. Animal models allow researchers to perform mechanistic studies, and the development of improved patient sample collection methods provides a platform for translational studies in vitiligo that can also be applied to understand other autoimmune diseases that are more difficult to study in human samples. Here we discuss the history of vitiligo translational research, recent advances, and their implications for new treatment approaches.

Pathophysiological Role and Therapeutic Implications of Vitamin D in Autoimmunity: Focus on Chronic Autoimmune Diseases

Vitamin D is a pleiotropic secosteroid yielding multiple actions in human physiology. Besides the canonical regulatory activity on bone metabolism, several non-classical actions have been described and the ability of vitamin D to partake in the regulation of the immune system is particularly interesting, though far stronger and convincing evidence has been collected in in vitro as compared to in vivo studies. Whether vitamin D is able to regulate at physiological concentrations the human immune system remains unproven to date. Consequently, it is not established if vitamin D status is a factor involved in the pathogenesis of immune-mediated diseases and if cholecalciferol supplementation acts as an adjuvant for autoimmune diseases. The development of autoimmunity is a heterogeneous process, which may involve different organs and systems with a wide range of clinical implications. In the present paper, we reviewed the current evidences regarding vitamin D role in the pathogenesis and management of different autoimmune diseases.

Epidemiology, pathogenesis, and diagnosis of Addison's disease in adults

BACKGROUND

Addison's disease (AD) is a rare disorder and among adult population in developed countries is most commonly caused by autoimmunity. In contrast, in children genetic causes are responsible for AD in the majority of patients.

PURPOSE

This review describes epidemiology, pathogenesis, genetics, natural history, clinical manifestations, immunological markers and diagnostic strategies in patients with AD. Standard care treatments including the management of patients during pregnancy and adrenal crises consistent with the recent consensus statement of the European Consortium and the Endocrine Society Clinical Practice Guideline are described. In addition, emerging therapies designed to improve the quality of life and new strategies to modify the natural history of autoimmune AD are discussed.

CONCLUSIONS

Progress in optimizing replacement therapy for patients with AD has allowed the patients to lead a normal life. However, continuous education of patients and health care professionals of ever-present danger of adrenal crisis is essential to save lives of patients with AD.

Coexistence of Congenital Adrenal Hyperplasia and Autoimmune Addison's Disease

Background: Underlying causes of adrenal insufficiency include congenital adrenal hyperplasia (CAH) and autoimmune adrenocortical destruction leading to autoimmune Addison's disease (AAD). Here, we report a patient with a homozygous stop-gain mutation in 3β-hydroxysteroid dehydrogenase type 2 (3βHSD2), in addition to impaired steroidogenesis due to AAD. Case Report: Whole exome sequencing revealed an extremely rare homozygous nonsense mutation in exon 2 of the HSD3B2 gene, leading to a premature stop codon (NM_000198.3: c.15C>A, p.Cys5Ter) in a patient with AAD and premature ovarian insufficiency. Scrutiny of old medical records revealed that the patient was initially diagnosed with CAH with hyperandrogenism and severe salt-wasting shortly after birth. However, the current steroid profile show complete adrenal insufficiency including low production of pregnenolone, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S), without signs of overtreatment with steroids. Conclusion: To the best of our knowledge, this is the first description of autoimmune adrenalitis in a patient with 3βHSD2 deficiency and suggests a possible association between AAD and inborn errors of the steroidogenesis.

Identification and characterization of rare toll-like receptor 3 variants in patients with autoimmune Addison's disease

Autoimmune Addison's disease (AAD) is a classic organ-specific autoimmune disease characterized by an immune-mediated attack on the adrenal cortex. As most autoimmune diseases, AAD is believed to be caused by a combination of genetic and environmental factors, and probably interactions between the two. Persistent viral infections have been suggested to play a triggering role, by invoking inflammation and autoimmune destruction. The inability of clearing infections can be due to aberrations in innate immunity, including mutations in genes involved in the recognition of conserved microbial patterns. In a whole exome sequencing study of anonymized AAD patients, we discovered several rare variants predicted to be damaging in the gene encoding Toll-like receptor 3 (TLR3). TLR3 recognizes double stranded RNAs, and is therefore a major factor in antiviral defense. We here report the occurrence and functional characterization of five rare missense variants in TLR3 of patients with AAD. Most of these variants occurred together with a common TLR3 variant that has been associated with a wide range of immunopathologies. The biological implications of these variants on TLR3 function were evaluated in a cell-based assay, revealing a partial loss-of-function effect of three of the rare variants. In addition, rare mutations in other members of the TLR3-interferon (IFN) signaling pathway were detected in the AAD patients. Together, these findings indicate a potential role for TLR3 and downstream signaling proteins in the pathogenesis in a subset of AAD patients.

DLA class II haplotypes show sex-specific associations with primary hypoadrenocorticism in Standard Poodle dogs

Addison's disease (AD) is a life-threatening endocrine disorder that occurs spontaneously in both humans and dogs. Associations between MHC class II genes and AD have been shown in several human studies. Our goal was to identify MHC class II associations with AD in a large population of Standard Poodles, a breed highly predisposed to AD. We sequenced exon 2 of the class II genes DLA-DRB1, DLA-DQA1, and DLA-DQB1 in 110 affected and 101 unaffected Standard Poodles and tested for association with AD. After correcting for population structure, two haplotypes were found to confer risk of developing AD in a sex-specific manner: DLA-DRB1*015:01-DQA1*006:01-DQB1*023:01 in males (x²p = 0.03, OR 2.1) and DLA-DRB1*009:01-DQA1*001:01-DQB1*008:01:1 in females (x²p = 0.02, OR 8.43). Sex-specific associations have been previously described in human populations, but this is the first report of this kind in dogs. Consistent with findings in other studies, we found the DLA-DQA1*006:01 allele (x²p = 0.04) to be associated with AD in males independent of haplotype. In females, the haplotype DLA-DRB1*009:01-DQA1*001:01-DQB1*008:01:1 confers a very high risk for developing AD, although its frequency was rare (9 of 124 females) in our study population. Further studies are warranted to validate the findings of this exploratory dataset and to assess the usefulness of this haplotype as a risk marker for AD in female Standard Poodles. Our results highlight the importance of evaluating MHC class II disease associations in large populations, and accounting for both biological sex and population structure.

The potential role for infections in the pathogenesis of autoimmune Addison's disease

Autoimmune Addison's disease (AAD), or primary adrenocortical insufficiency, is a classical organ-specific autoimmune disease with 160 years of history. AAD is remarkably homogeneous with one major dominant self-antigen, the cytochrome P450 21-hydroxylase enzyme, which is targeted by both autoantibodies and autoreactive T cells. Like most autoimmune diseases, AAD is thought to be caused by an unfortunate combination of genetic and environmental factors. While the number of genetic associations with AAD is increasing, almost nothing is known about environmental factors. A major environmental factor commonly proposed for autoimmune diseases, based partly on experimental and clinical data and partly on shared pathways between anti-viral immunity and autoimmunity, is viral infections. However, there are few reports associating viral infections to AAD, and it has proved difficult to establish which immunological processes that could link any viral infection with the initiation or progression of AAD. In this review, we will summarize the current knowledge on the underlying mechanisms of AAD and take a closer look on the potential involvement of viruses.

MANAGEMENT OF ENDOCRINE DISEASE: Fertility, pregnancy and lactation in women with adrenal insufficiency

With the introduction of hormonal substitution therapy in the 1950s, adrenal insufficiency (AI) has been turned into a manageable disease in pregnant women. In fact, in the light of glucocorticoid replacement therapy and improved obstetric care, it is realistic to expect good maternal and fetal outcomes in patients with AI. However, there are still a number of challenges such as establishing the diagnosis of AI in pregnant women and optimizing the treatment of AI and related comorbidities prior to as well as during pregnancy. Clinical and biochemical diagnoses of a new-onset AI may be challenging because of overlapping symptoms of normal pregnancy as well as pregnancy-induced changes in cortisol values. Physiological changes occurring during pregnancy should be taken into account while adjusting the substitution therapy. The high proportion of reported adrenal crisis in pregnant women with AI highlights persistent problems in this particular clinical situation. Due to the rarity of the disease, there is no prospective data-guiding management of pregnancy in patients with known AI. The aim of this review is to summarize the maternal and fetal outcomes based on recently published case reports in patients with AI and to suggest a practical approach to diagnose and manage AI in pregnancy.

High-dose vitamin D in Addison's disease regulates T-cells and monocytes: A pilot trial

OBJECTIVES

On the basis of the immunomodulatory actions of vitamin D (VD), we investigated the effects of high-dose VD therapy over a 3 mo period on the immune response in patients with Addison's disease (AD).

METHODS

This randomized, controlled, crossover trial included 13 patients with AD who received either cholecalciferol (4000 IU/d) for 3 mo followed by 3 mo placebo oil or the sequential alternative placebo followed by verum. Glucocorticoid replacement doses remained stable. The primary outcome measures were changes in 25-hydroxyvitamin D3 (25(OH)D₃) levels and immune cells including T helper cells (Th; CD3⁺CD4⁺), late-activated Th cells (CD3⁺CD4⁺HLA-DR⁺), regulatory T cells (CD3⁺CD4⁺CD25^brightCD127^dim/neg), cytotoxic T cells (Tc; CD3⁺CD8⁺), late-activated Tc cells (CD3⁺CD8⁺HLA-DR⁺), and monocytes. The explorative analysis included the correlation of changes with VD-related gene polymorphisms and 21-hydroxylase antibody titers.

RESULTS

Ten of 13 patients (77%) were VD deficient. Median 25(OH)D₃ concentrations increased significantly to 41.5 ng/ml (median changes: 19.95 ng/ml; P = 0.0005) after 3 mo of cholecalciferol treatment. Within the T-cells, only the late-activated Th (median changes: 1.6%; P = 0.02) and late-activated Tc cells (median changes: 4.05%; P = 0.03) decreased, whereas monocytes (median changes: 1.05%; P = 0.008) increased after VD therapy. T-cell changes were associated with two polymorphisms (CYP27B1-rs108770012 and VDR-rs10735810), but no changes in the 21-hydroxylase antibody titers were observed.

CONCLUSIONS

Three months of treatment with cholecalciferol achieved sufficient 25(OH)D₃ levels and can regulate late-activated T-cells and monocytes in patients with AD. Explorative analysis revealed potential genetic contributions. This pilot trial provides novel insights about immunomodulation in AD.

Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept

In the last few years, more attention has been given to the "non-calcemic" effect of vitamin D. Several observational studies and meta-analyses demonstrated an association between circulating levels of vitamin D and outcome of many common diseases, including endocrine diseases, chronic diseases, cancer progression, and autoimmune diseases. In particular, cells of the immune system (B cells, T cells, and antigen presenting cells), due to the expression of 1α-hydroxylase (CYP27B1), are able to synthesize the active metabolite of vitamin D, which shows immunomodulatory properties. Moreover, the expression of the vitamin D receptor (VDR) in these cells suggests a local action of vitamin D in the immune response. These findings are supported by the correlation between the polymorphisms of the VDR or the CYP27B1 gene and the pathogenesis of several autoimmune diseases. Currently, the optimal plasma 25-hydroxyvitamin D concentration that is necessary to prevent or treat autoimmune diseases is still under debate. However, experimental studies in humans have suggested beneficial effects of vitamin D supplementation in reducing the severity of disease activity. In this review, we summarize the evidence regarding the role of vitamin D in the pathogenesis of autoimmune endocrine diseases, including type 1 diabetes mellitus, Addison's disease, Hashimoto's thyroiditis, Graves' disease and autoimmune polyendocrine syndromes. Furthermore, we discuss the supplementation with vitamin D to prevent or treat autoimmune diseases.

Autoantibody Repertoire in APECED Patients Targets Two Distinct Subgroups of Proteins

High titer autoantibodies produced by B lymphocytes are clinically important features of many common autoimmune diseases. APECED patients with deficient autoimmune regulator (AIRE) gene collectively display a broad repertoire of high titer autoantibodies, including some which are pathognomonic for major autoimmune diseases. AIRE deficiency severely reduces thymic expression of gene-products ordinarily restricted to discrete peripheral tissues, and developing T cells reactive to those gene-products are not inactivated during their development. However, the extent of the autoantibody repertoire in APECED and its relation to thymic expression of self-antigens are unclear. We here undertook a broad protein array approach to assess autoantibody repertoire in APECED patients. Our results show that in addition to shared autoantigen reactivities, APECED patients display high inter-individual variation in their autoantigen profiles, which collectively are enriched in evolutionarily conserved, cytosolic and nuclear phosphoproteins. The APECED autoantigens have two major origins; proteins expressed in thymic medullary epithelial cells and proteins expressed in lymphoid cells. These findings support the hypothesis that specific protein properties strongly contribute to the etiology of B cell autoimmunity.

Lymphocyte Subsets in the Adrenal Glands of Dogs With Primary Hypoadrenocorticism

Primary hypoadrenocorticism, or Addison's disease, is an autoimmune condition common in certain dog breeds that leads to the destruction of the adrenal cortex and a clinical syndrome involving anorexia, gastrointestinal upset, and electrolyte imbalances. Previous studies have demonstrated that this destruction is strongly associated with lymphocytic-plasmacytic inflammation and that the lymphocytes are primarily T cells. In this study, we used both immunohistochemistry and in situ hybridization to characterize the T-cell subtypes involved. We collected postmortem specimens of 5 dogs with primary hypoadrenocorticism and 2 control dogs and, using the aforementioned techniques, showed that the lymphocytes are primarily CD4+ rather than CD8+. These findings have important implications for improving our understanding of the pathogenesis and in searching for the underlying causative genetic polymorphisms.

Analysis of cellular and humoral immune responses against cytomegalovirus in patients with autoimmune Addison's disease

Background

Autoimmune Addison’s disease (AAD) is caused by multiple genetic and environmental factors. Variants of genes encoding immunologically important proteins such as the HLA molecules are strongly associated with AAD, but any environmental risk factors have yet to be defined. We hypothesized that primary or reactivating infections with cytomegalovirus (CMV) could represent an environmental risk factor in AAD, and that CMV specific CD8⁺ T cell responses may be dysregulated, possibly leading to a suboptimal control of CMV. In particular, the objective was to assess the HLA-B8 restricted CD8⁺ T cell response to CMV since this HLA class I variant is a genetic risk factor for AAD.

Methods

To examine the CD8⁺ T cell response in detail, we analyzed the HLA-A2 and HLA-B8 restricted responses in AAD patients and healthy controls seropositive for CMV antibodies using HLA multimer technology, IFN-γ ELISpot and a CD107a based degranulation assay.

Results

No differences between patients and controls were found in functions or frequencies of CMV-specific T cells, regardless if the analyses were performed ex vivo or after in vitro stimulation and expansion. However, individual patients showed signs of reactivating CMV infection correlating with poor CD8⁺ T cell responses to the virus, and a concomitant upregulation of interferon regulated genes in peripheral blood cells. Several recently diagnosed AAD patients also showed serological signs of ongoing primary CMV infection.

Conclusions

CMV infection does not appear to be a major environmental risk factor in AAD, but may represent a precipitating factor in individual patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0822-z) contains supplementary material, which is available to authorized users.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is an autosomal recessive disease caused by mutations in the autoimmune regulator (AIRE) gene. This review focuses on the clinical and immunological features of APECED, summarizes the current knowledge on the function of AIRE and discusses the importance of autoantibodies in disease diagnosis and prognosis. Additionally, we review the outcome of recent immunomodulatory treatments in APECED patients.

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.

Mechanisms in endocrinology: vitamin D as a potential contributor in endocrine health and disease

OBJECTIVE

It has been suggested that vitamin D may play a role in the pathogenesis of several endocrine diseases, such as hyperparathyroidism, type 1 diabetes (T1DM), type 2 diabetes (T2DM), autoimmune thyroid diseases, Addison's disease and polycystic ovary syndrome (PCOS). In this review, we debate the role of vitamin D in the pathogenesis of endocrine diseases.

METHODS

Narrative overview of the literature synthesizing the current evidence retrieved from searches of computerized databases, hand searches and authoritative texts.

RESULTS

Evidence from basic science supports a role for vitamin D in many endocrine conditions. In humans, inverse relationships have been reported not only between blood 25-hydroxyvitamin D and parathyroid hormone concentrations but also with risk of T1DM, T2DM, and PCOS. There is less evidence for an association with Addison's disease or autoimmune thyroid disease. Vitamin D supplementation may have a role for prevention of T2DM, but the available evidence is not consistent.

CONCLUSIONS

Although observational studies support a potential role of vitamin D in endocrine disease, high quality evidence from clinical trials does not exist to establish a place for vitamin D supplementation in optimizing endocrine health. Ongoing randomized controlled trials are expected to provide insights into the efficacy and safety of vitamin D in the management of endocrine disease.

Adrenal insufficiency

Adrenal insufficiency is the clinical manifestation of deficient production or action of glucocorticoids, with or without deficiency also in mineralocorticoids and adrenal androgens. It is a life-threatening disorder that can result from primary adrenal failure or secondary adrenal disease due to impairment of the hypothalamic-pituitary axis. Prompt diagnosis and management are essential. The clinical manifestations of primary adrenal insufficiency result from deficiency of all adrenocortical hormones, but they can also include signs of other concurrent autoimmune conditions. In secondary or tertiary adrenal insufficiency, the clinical picture results from glucocorticoid deficiency only, but manifestations of the primary pathological disorder can also be present. The diagnostic investigation, although well established, can be challenging, especially in patients with secondary or tertiary adrenal insufficiency. We summarise knowledge at this time on the epidemiology, causal mechanisms, pathophysiology, clinical manifestations, diagnosis, and management of this disorder.

The effect of types I and III interferons on adrenocortical cells and its possible implications for autoimmune Addison's disease

Autoimmune Addison's disease (AAD) is caused by selective destruction of the hormone-producing cells of the adrenal cortex. As yet, little is known about the potential role played by environmental factors in this process. Type I and/or type III interferons (IFNs) are signature responses to virus infections, and have also been implicated in the pathogenesis of autoimmune endocrine disorders such as type 1 diabetes and autoimmune thyroiditis. Transient development of AAD and exacerbation of established or subclinical disease, as well as the induction of autoantibodies associated with AAD, have been reported following therapeutic administration of type I IFNs. We therefore hypothesize that exposure to such IFNs could render the adrenal cortex susceptible to autoimmune attack in genetically predisposed individuals. In this study, we investigated possible immunopathological effects of type I and type III IFNs on adrenocortical cells in relation to AAD. Both types I and III IFNs exerted significant cytotoxicity on NCI-H295R adrenocortical carcinoma cells and potentiated IFN-γ- and polyinosine-polycytidylic acid [poly (I : C)]-induced chemokine secretion. Furthermore, we observed increased expression of human leucocyte antigen (HLA) class I molecules and up-regulation of 21-hydroxylase, the primary antigenic target in AAD. We propose that these combined effects could serve to initiate or aggravate an ongoing autoimmune response against the adrenal cortex in AAD.

Correlation of inflammation with adrenocortical atrophy in canine adrenalitis

Hypoadrenocorticism or Addison's disease (AD) is a functional disorder in which insufficient mineralocorticoid and glucocorticoid hormones are produced by the adrenal cortex. Human AD is usually attributed to lymphoplasmacytic adrenalitis with autoimmune destruction of the adrenal cortex. Lymphoplasmacytic adrenalitis is also reported in some descriptions of canine AD; however, the histological aspects of adrenalitis or adrenocortical atrophy have not been well characterized because microscopical examination is not required for diagnosis of AD. In this study, sections of adrenal glands from 33 dogs with adrenalitis were compared with those of 37 dogs without adrenal lesions. The affected dogs were classified clinically as having AD (n = 3), being suspected of having AD (n = 17), not having AD (n = 11) or were unclassified (n = 2). The adrenal inflammation was lymphoplasmacytic in 17 dogs, lymphocytic in four, lymphohistiocytic in one, granulomatous in three and neutrophilic in eight cases. Adrenal glands from control dogs lacked leucocyte infiltration and had a cortical to medullary area ratio of 1.1-7.2. All three dogs with AD, 8/17 dogs with suspected AD and 1/11 dogs without AD had a cortical to medullary area ratio <1.1. Because the area ratio was correlated (r = 0.94) with a linear cortical to medullary thickness ratio, a thickness ratio <1.1 could also indicate severe adrenocortical atrophy. Severe adrenocortical atrophy was associated typically with lymphoplasmacytic infiltration and nearly complete loss of cortical cells; however, the zona glomerulosa was partially spared in three dogs with lymphoplasmacytic adrenalitis and severe cortical atrophy. In contrast, non-lymphoid inflammation was generally part of systemic disease, multifocal and was unaccompanied by severe adrenocortical atrophy.

Induction of CXCL10 chemokine in adrenocortical cells by stimulation through toll-like receptor 3

Addison's disease is a prototypic organ-specific autoimmune disease affecting the adrenal cortex. The CXC chemokine ligand 10 (CXCL10) is expressed early in viral infections, and is produced by primary adrenocortical cells stimulated by certain cytokines. CXCL10 is also elevated in the serum of Addison's disease patients. We therefore investigated if the viral RNA substitute polyinosine-polycytidylic acid (poly (I:C)) could influence the cytokine induced production of CXCL10 by adrenocortical cells. We found that poly (I:C) could induce CXCL10 in NCI-H295R adrenocortical carcinoma cells, either alone or synergistically along with cytokines interferon-γ and tumor necrosis factor-α. This effect was found to be mediated by toll-like receptor 3 and both nuclear factor κB (NFκB) and signal transducer and activator of transcription-1 (STAT1), but not type I interferons, seemed to be involved. We propose that the combination of environmental and endogenous factors presented here, could contribute to the multifactorial pathogenesis of autoimmune Addison's disease.

[Subclinical adrenal diseases: silent pheochromocytoma and subclinical Addison's disease]

The silent pheochromocytoma, a hidden form of pheochromocytoma, exposes the patient to an increased risk of mortality if the diagnosis is not established on time. Biological diagnosis of pheochromocytoma can be difficult. Catecholamine secretion is dependent on tumor size and a large number of physiological, pharmacological, lifestyle modifications and sampling conditions influence the measurement of urinary and plasma metanephrines. The prevalence of pheochromocytoma is 2% among adrenal incidentaloma smaller than 3 cm (2/3 of tumors). Recent studies suggest the almost zero risk of pheochromocytoma among these tumors if they are hypodense (<10 housefield units) on adrenal tomography. Addison's disease is a pathology affecting about 1 in 8000. Immunopathology is still unknown, but some elements advocated the hypothesis of a predominant cell-mediated immunity in particular Interferon-gamma production by CD4 T lymphocytes in the presence of an epitope from the 21-hydroxylase, as well as IgG1 subtype produced by activated B lymphocytes, autoantibodies do appear to be a simple marker of the disease. Subclinical Addison's disease is defined by the presence of anti-21-hydroxylase autoantibodies, without clinical symptoms. It evolves faster to the clinical phase in young subjects, male, having high levels of autoantibodies and with an initially impaired adrenal function. Dosage of ACTH, plasma renin active, and basal cortisol and after Synacthen allow to discriminate the subjects with low or high risk of evolution and establish an appropriate monitoring.