T cell responses to steroid cytochrome P450 21-hydroxylase in patients with autoimmune primary adrenal insufficiency

Regulatory T cells in autoimmune primary adrenal insufficiency

Primary adrenal insufficiency (PAI) is most often caused by an autoimmune destruction of the adrenal cortex resulting in failure to produce cortisol and aldosterone. The aetiology is thought to be a combination of genetic and environmental risk factors, leading to breakdown of immunological tolerance. Regulatory T cells (Tregs) are deficient in many autoimmune disorders, but it is not known whether they contribute to development of PAI. We aimed to investigate the frequency and function of naive and expanded Tregs in patients with PAI and polyendocrine syndromes compared to age- and gender-matched healthy controls. Flow cytometry was used to assess the frequency and characterize functional markers of blood Tregs in PAI (N = 15). Expanded Treg suppressive abilities were assessed with a flow cytometry based suppression assay (N = 20), while bulk RNA-sequencing was used to examine transcriptomic differences (N = 16) and oxygen consumption rate was measured by a Seahorse cell metabolic assay (N = 11). Our results showed that Treg frequency and suppressive capacity were similar between patients and controls. An increased expression of killer-cell leptin-like receptors and mitochondrial genes was revealed in PAI patients, but their expanded Tregs did not display signs of mitochondrial dysfunction. Our findings do not support a clear role for Tregs in the contribution of PAI development.

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.

Ketogenic diet promotes tumor ferroptosis but induces relative corticosterone deficiency that accelerates cachexia

Glucose dependency of cancer cells can be targeted with a high-fat, low-carbohydrate ketogenic diet (KD). However, in IL-6-producing cancers, suppression of the hepatic ketogenic potential hinders the utilization of KD as energy for the organism. In IL-6-associated murine models of cancer cachexia, we describe delayed tumor growth but accelerated cachexia onset and shortened survival in mice fed KD. Mechanistically, this uncoupling is a consequence of the biochemical interaction of two NADPH-dependent pathways. Within the tumor, increased lipid peroxidation and, consequently, saturation of the glutathione (GSH) system lead to the ferroptotic death of cancer cells. Systemically, redox imbalance and NADPH depletion impair corticosterone biosynthesis. Administration of dexamethasone, a potent glucocorticoid, increases food intake, normalizes glucose levels and utilization of nutritional substrates, delays cachexia onset, and extends the survival of tumor-bearing mice fed KD while preserving reduced tumor growth. Our study emphasizes the need to investigate the effects of systemic interventions on both the tumor and the host to accurately assess therapeutic potential. These findings may be relevant to clinical research efforts that investigate nutritional interventions such as KD in patients with cancer.

The ISAQ Score Does Not Predict Adrenal Crisis in Patients with Primary Adrenal Insufficiency

OBJECTIVE

This study aimed to investigate the ability of the immune system assessment questionnaire (ISAQ) to predict adrenal crisis (AC) and infectious events in patients with primary adrenal insufficiency (PAI).

DESIGN

This was a prospective single-centre study over three years.

METHODS

Patients answered the ISAQ at baseline and were seen every 4-6 months in the endocrine outpatient clinic. At each visit previous infectious periods which required an increase in daily glucocorticoid dosage and AC were reported and documented. Seventy-five patients with PAI (53 women; 43 patients with autoimmune PAI, 20 patients with salt-wasting congenital adrenal hyperplasia and 12 patients who underwent bilateral adrenalectomy) were analysed. Due to the COVID-19 pandemic and consecutive lockdown measures, the data were analysed separately for March 2018 to March 2020 (period 1), and March 2020 to March 2021 (period 2).

RESULTS

During period 1 the ISAQ score significantly correlated with the number of reported infectious events (r=0.351; p<0.01), but not during period 2 (r=0.059, p=0.613), in which the number of infectious events per patient-year significantly decreased (1.1±0.1 vs 0.4±0.1; p<0.001). The frequency of AC decreased from 8.8 to 2.4 per 100 patient-years between the two study periods. The ISAQ score was not different between patients with or without AC.

CONCLUSIONS

The ISAQ score does not identify patients prone to ACs. The COVID-19 pandemic and consecutive lockdown measures significantly diminished the frequency of infectious events and ACs.

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.

Adrenal insufficiency

Adrenal insufficiency can arise from a primary adrenal disorder, secondary to adrenocorticotropic hormone deficiency, or by suppression of adrenocorticotropic hormone by exogenous glucocorticoid or opioid medications. Hallmark clinical features are unintentional weight loss, anorexia, postural hypotension, profound fatigue, muscle and abdominal pain, and hyponatraemia. Additionally, patients with primary adrenal insufficiency usually develop skin hyperpigmentation and crave salt. Diagnosis of adrenal insufficiency is usually delayed because the initial presentation is often non-specific; physician awareness must be improved to avoid adrenal crisis. Despite state-of-the-art steroid replacement therapy, reduced quality of life and work capacity, and increased mortality is reported in patients with primary or secondary adrenal insufficiency. Active and repeated patient education on managing adrenal insufficiency, including advice on how to increase medication during intercurrent illness, medical or dental procedures, and profound stress, is required to prevent adrenal crisis, which occurs in about 50% of patients with adrenal insufficiency after diagnosis. It is good practice for physicians to provide patients with a steroid card, parenteral hydrocortisone, and training for parenteral hydrocortisone administration, in case of vomiting or severe illness. New modes of glucocorticoid delivery could improve the quality of life in some patients with adrenal insufficiency, and further advances in oral and parenteral therapy will probably emerge in the next few years.

Th1 Chemokines in Autoimmune Endocrine Disorders

CONTEXT

The CXC chemokine receptor CXCR3 and its chemokines CXCL10, CXCL9, and CXCL11 are implicated in the pathogenesis of autoimmune diseases. Here, we review these chemokines in autoimmune thyroiditis (AT), Graves disease (GD), thyroid eye disease (TED), type 1 diabetes (T1D), and Addison's disease (AAD).

EVIDENCE ACQUISITION

A PubMed review of the literature was conducted, searching for the above-mentioned chemokines in combination with AT, GD, TED, T1D, and AAD.

EVIDENCE SYNTHESIS

Thyroid follicular cells in AT and GD, retroorbital cells in TED (fibroblasts, preadipocytes, myoblasts), β cells and islets in T1D, and adrenal cells in AAD respond to interferon-γ (IFN-γ) stimulation producing large amounts of these chemokines. Furthermore, lymphocytes and peripheral blood mononuclear cells (PBMC) are in part responsible for the secreted Th1 chemokines. In AT, GD, TED, T1D, and AAD, the circulating levels of these chemokines have been shown to be high. Furthermore, these chemokines have been associated with the early phases of the autoimmune response in all the above-mentioned disorders. High levels of these chemokines have been associated also with the "active phase" of the disease in GD, and also in TED. Other studies have shown an association with the severity of hypothyroidism in AD, of hyperthyroidism in GD, with severity of TED, or with fulminant T1D.

CONCLUSION

The reviewed data have shown the importance of the Th1 immune response in different endocrine autoimmune diseases, and many studies have suggested that CXCR3 and its chemokines might be considered as potential targets of new drugs for the treatment of these disorders.

Mass Cytometry Studies of Patients With Autoimmune Endocrine Diseases Reveal Distinct Disease-Specific Alterations in Immune Cell Subsets

Although there is evidence that autoimmune diseases share similar immunogenetic mechanisms, studies comparing peripheral CD45⁺ cells from patients with autoimmune endocrine diseases in parallel are limited. In this study, we applied high-dimensional single-cell mass cytometry to phenotypically characterize PBMC from patients with new-onset (N-T1D) and long-standing type 1 diabetes, Hashimoto's thyroiditis (HT), Graves' disease and autoimmune Addison's disease (AD), as well as healthy controls. The frequency of CD20^loCD27^hiCD38^hiHLA-DR^int plasmablasts, CD86⁺CD14^loCD16⁺ non-classical monocytes and two subsets of CD56^dimHLA-DR⁺IFN-γ⁺ NK cells were increased in patients with HT. Subsets of CD56^dimCD69⁺HLA-DR^- NK cells and CD8⁺ TEMRA cells, both expressing IFN-γ, were expanded and reduced, respectively, in the N-T1D group. In addition, patients with AD were characterized by an increased percentage of central memory CD8⁺ T cells that expressed CCR4, GATA3, and IL-2. We demonstrate that patients with N-T1D, HT, and AD had altered frequencies of distinct subsets within antigen-presenting and cytotoxic cell lineages. Previously unreported alterations of specific cell subsets were identified in samples from patients with HT and AD. Our study might contribute to a better understanding of shared and diverging immunological features between autoimmune endocrine diseases.

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.

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.

Autoimmune Addison's disease - An update on pathogenesis

Autoimmunity against the adrenal cortex is the leading cause of Addison's disease in industrialized countries, with prevalence estimates ranging from 93-220 per million in Europe. The immune-mediated attack on adrenocortical cells cripples their ability to synthesize vital steroid hormones and necessitates life-long hormone replacement therapy. The autoimmune disease etiology is multifactorial involving variants in immune genes and environmental factors. Recently, we have come to appreciate that the adrenocortical cell itself is an active player in the autoimmune process. Here we summarize the complex interplay between the immune system and the adrenal cortex and highlight unanswered questions and gaps in our current understanding of the disease.

A Variant in the BACH2 Gene Is Associated With Susceptibility to Autoimmune Addison's Disease in Humans

CONTEXT

Autoimmune Addison's disease (AAD) is a rare but highly heritable condition. The BACH2 protein plays a crucial role in T lymphocyte maturation, and allelic variation in its gene has been associated with a number of autoimmune conditions.

OBJECTIVE

We aimed to determine whether alleles of the rs3757247 single nucleotide polymorphism (SNP) in the BACH2 gene are associated with AAD.

DESIGN, SETTING, AND PATIENTS

This case-control association study was performed in two phases using Taqman chemistry. In the first phase, the rs3757247 SNP was genotyped in 358 UK AAD subjects and 166 local control subjects. Genotype data were also available from 5154 healthy UK controls from the Wellcome Trust (WTCCC2) for comparison. In the second phase, the SNP was genotyped in a validation cohort comprising 317 Norwegian AAD subjects and 365 controls.

RESULTS

The frequency of the minor T allele was significantly higher in subjects with AAD from the United Kingdom compared to both the local and WTCCC2 control cohorts (58% vs 45 and 48%, respectively) (local controls, P = 1.1 × 10^-4; odds ratio [OR], 1.68; 95% confidence interval [CI], 1.29-2.18; WTCCC2 controls, P = 1.4 × 10^-6; OR, 1.44; 95% CI, 1.23-1.69). This finding was replicated in the Norwegian validation cohort (P = .0015; OR, 1.41; 95% CI, 1.14-1.75). Subgroup analysis showed that this association is present in subjects with both isolated AAD (OR, 1.53; 95% CI, 1.22-1.92) and autoimmune polyglandular syndrome type 2 (OR, 1.37; 95% CI, 1.12-1.69) in the UK cohort, and with autoimmune polyglandular syndrome type 2 in the Norwegian cohort (OR, 1.58; 95% CI, 1.22-2.06).

CONCLUSION

We have demonstrated, for the first time, that allelic variability at the BACH2 locus is associated with susceptibility to AAD. Given its association with multiple autoimmune conditions, BACH2 can be considered a "universal" autoimmune susceptibility locus.

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.

Interleukin-2 and subunit alpha of its soluble receptor in autoimmune Addison's disease--an association study and expression analysis

Autoimmune Addison's disease (AAD) results from T cell-mediated destruction of the adrenal cortex, commonly accompanied by autoantibodies to 21-hydroxylase (21OH). In order to gain insight into the obscure aetiology of this disease, we investigated the roles of the IL2 and IL2RA genes, encoding interleukin-2 and subunit alpha of its receptor (IL2Ra), respectively. The association of AAD with IL2 and IL2RA polymorphisms (rs6822844, rs2069762, rs3136534, rs11594656, rs3118470 and rs2104286) was tested in 223 patients and 672 healthy controls. Functional studies consisted of gene expression analysis in cultured PBMCs exposed to 21OH and evaluation of serum interleukin by ELISA assays. The frequency of the minor C allele of rs3136534 was significantly decreased in AAD subjects compared to controls (OR 0.71; 95%CI 0.561-0.887; p = 0.003). Only AAD cells responded to 21OH with an elevated IL2 and IL2RA mRNA synthesis (p = 0.004 and p = 0.009 versus controls, respectively), paralleled by increased supernatant levels of both cytokines (p = 0.031 and p = 0.001 versus controls). IL2 mRNA level in 21OH-stimulated AAD PBMCs correlated negatively with age (p = 0.036) and positively with serum antibodies to 21OH (p = 0.006). Carriers of the rs2104286 AA genotype demonstrated higher IL2RA mRNA (p = 0.022) and soluble IL2Ra secretion (p = 0.029) upon 21OH stimulation. Serum interleukin-2 in AAD subjects was significantly higher compared to controls (4.61 ± 4.3 versus 1.71 ± 3.2 pg/mL, p < 0.001), whereas sIL2Ra levels remained similar in both groups (p = 0.885). In conclusion, the study reveals an association between AAD and IL2 locus. It confirms specific 21OH-directed reactivity of the peripheral AAD lymphocytes, which display increased synthesis of interleukin-2 and sIL2Ra.

Clinical and serologic parallels to APS-I in patients with thymomas and autoantigen transcripts in their tumors

Patients with the autoimmune polyendocrine syndrome type I (APS-I), caused by mutations in the autoimmune regulator (AIRE) gene, and myasthenia gravis (MG) with thymoma, show intriguing but unexplained parallels. They include uncommon manifestations like autoimmune adrenal insufficiency (AI), hypoparathyroidism, and chronic mucocutaneous candidiasis plus autoantibodies neutralizing IL-17, IL-22, and type I IFNs. Thymopoiesis in the absence of AIRE is implicated in both syndromes. To test whether these parallels extend further, we screened 247 patients with MG, thymoma, or both for clinical features and organ-specific autoantibodies characteristic of APS-I patients, and we assayed 26 thymoma samples for transcripts for AIRE and 16 peripheral tissue-specific autoantigens (TSAgs) by quantitative PCR. We found APS-I-typical autoantibodies and clinical manifestations, including chronic mucocutaneous candidiasis, AI, and asplenia, respectively, in 49 of 121 (40%) and 10 of 121 (8%) thymoma patients, but clinical features seldom occurred together with the corresponding autoantibodies. Both were rare in other MG subgroups (n = 126). In 38 patients with APS-I, by contrast, we observed neither autoantibodies against muscle Ags nor any neuromuscular disorders. Whereas relative transcript levels for AIRE and 7 of 16 TSAgs showed the expected underexpression in thymomas, levels were increased for four of the five TSAgs most frequently targeted by these patients' autoantibodies. Therefore, the clinical and serologic parallels to APS-I in patients with thymomas are not explained purely by deficient TSAg transcription in these aberrant AIRE-deficient tumors. We therefore propose additional explanations for the unusual autoimmune biases they provoke. Thymoma patients should be monitored for potentially life-threatening APS-I manifestations such as AI and hypoparathyroidism.

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.

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.

Insights into type 1 diabetes from the autoimmune polyendocrine syndromes

PURPOSE OF REVIEW

Advances in human genetics and investigations in animal models of autoimmune disease have allowed insight into the basic mechanisms of immunologic tolerance. These advances allow us to understand the pathogenesis of type 1 diabetes and other autoimmune diseases as never before. Here, we discuss the tolerance mechanisms of the autoimmune polyendocrine syndromes and their relevance to type 1 diabetes.

RECENT FINDINGS

Defects in central tolerance with alteration of self-antigen expression levels in the thymus are a potent cause of autoimmunity. Peripheral tolerance defects that alter T-cell activation and signaling also play an important role in the pathogenesis of diabetes and other associated autoimmune disorders, with multiple modest defects working in concert to produce disease. Regulation of the immune response through the action of regulatory T cells is a potent mode of tolerance induction in autoimmunity that is important in type 1 diabetes.

SUMMARY

Rare syndromes of autoimmunity provide a valuable window into the breakdown of tolerance and identify multiple checkpoints that are critical for generation of autoimmunity. Understanding the application of these in type 1 diabetes will allow the development of future immunomodulatory therapies in the treatment and prevention of disease.

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.

Autoimmune Addison's disease

Addison's disease is a rare autoimmune disorder. In the developed world, autoimmune adrenalitis is the commonest cause of primary adrenal insufficiency, where the majority of patients have circulating antibodies against the key steroidogenic enzyme 21-hydroxylase. A complex interplay of genetic, immunological and environmental factors culminates in symptomatic adrenocortical insufficiency, with symptoms typically developing over months to years. Biochemical evaluation and further targeted investigations must confirm primary adrenal failure and establish the underlying aetiology. The diagnosis of adrenocortical insufficiency will necessitate lifelong glucocorticoid and mineralocorticoid replacement therapy, aiming to emulate physiological patterns of hormone secretion to achieve well-being and good quality of life. Education of patients and healthcare professionals is essential to minimise the risk of a life-threatening adrenal crisis, which must be promptly recognised and aggressively managed when it does occur. This article provides an overview of our current understanding of the natural history and underlying genetic and immunological basis of this condition. Future research may reveal novel therapeutic strategies for patient management. Until then, optimisation of pharmacological intervention and continued emphasis on education and empowerment of patients should underpin the management of individuals with 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.

The cytochrome P450 inhibitor, ketoconazole, inhibits oxidized linoleic acid metabolite-mediated peripheral inflammatory pain

Background

Oxidized linoleic acid metabolites (OLAMs) are a class of endogenous agonists to the transient receptor potential V1 (TRPV1) receptor. Although TRPV1 mediates inflammatory heat hyperalgesia, it is not known if the OLAMs contribute to the peripheral activation of this receptor during tissue inflammation. In the present study, we evaluated whether the OLAM system is activated during inflammation and whether cytochrome P450 enzymes mediate OLAM contributions to heat hyperalgesia using the complete Freund’s adjuvant (CFA) model of inflammation.

Results

Our results demonstrate that the intraplantar (ipl) injection of anti-OLAM antibodies significantly reversed CFA-induced heat hyperalgesia. Moreover, application of lipid extracts from inflamed rat skin to cultured sensory neurons triggered a significant release of iCGRP that is blocked by co-treatment with I-RTX, a TRPV1 antagonist. To determine the role of CYP enzymes in mediating OLAM effects, we used a broad spectrum CYP inhibitor, ketoconazole. Pretreatment with ketoconazole inhibited the release of TRPV1 agonists in lipid extracts from inflamed skin and significantly reversed CFA-induced heat hyperalgesia by a peripheral mechanism of action. Moreover, the ipl injection of linoleic acid to rats 24 hr after CFA evoked spontaneous nocifensive behaviors that were significantly reduced by capsazepine, by knockout of the TRPV1 gene, or by pretreatment with either anti-OLAM antibodies or ketoconazole.

Conclusions

Taken together, our data suggests that OLAMs contribute to inflammatory nociception in the periphery and that cytochrome P450 enzymes play a crucial role in mediating OLAM contributions to inflammatory heat hyperalgesia.

APECED: is this a model for failure of T cell and B cell tolerance?

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.

Autoimmune polyglandular syndrome type 2 shows the same HLA class II pattern as type 1 diabetes

Autoimmune polyglandular syndrome (APS) type 2 is defined by the manifestation of at least two autoimmune endocrine diseases. Only few data exist on genetic associations of APS type 2. In this controlled study, 98 patients with APS type 2, 96 patients with type 1 diabetes (T1D), and 92 patients with autoimmune thyroid disease, both as a single autoimmune endocrinopathy, were tested for association with alleles of the human leukocyte antigen (HLA) class II loci DRB1, DQA1, and DQB1. Patients with APS type 2 had significantly more often the alleles DRB1*03 (P(c) < 0.0001), DRB1*04 (P(c) < 0.000005), DQA1*03 (P(c) < 0.0001), and DQB1*02 (P(c) < 0.05), when compared with controls. Less frequent in APS were DRB1*15 (P(c) < 0.05), DQA1*01 (P(c) < 0.0005), and DQB1*05 (P(c) < 0.005). With regard to frequency and linkage of these alleles, the susceptible haplotypes DRB1*0301-DQA1*0501-DQB1*0201 and DRB1*0401/04-DQA1*0301-DQB1*0302 were deduced. Protective haplotypes in this study were DRB1*1501-DQA1*0102-DQB1*0602 and DRB1*0101-DQA1*0101-DQB1*0501. Comparing APS patients with vs without AD, no significant differences regarding HLA class II alleles were noted in our collective. Patients with T1D as a singular disease had the same susceptible and protective HLA alleles and haplotypes. The prevalence of DRB1*03 and DRB1*04 in APS patients was not because of the presence of diabetes, as the APS type 2 patients without diabetes had the same allele distribution. In conclusion, these data suggest a common immunogenetic pathomechanism for T1D and APS type 2, which might be different from the immunogenetic pathomechanism of other autoimmune endocrine disease.

Cellular immunity and immunopathology in autoimmune Addison's disease

Autoimmune adrenocortical failure, or Addison's disease, is a prototypical organ-specific autoimmune disorder. In common with related autoimmune endocrinopathies, Addison's disease is only manageable to a certain extent with replacement therapy being the only treatment option. Unfortunately, the available therapy does not restore the physiological hormone levels and biorhythm. The key to progress in treating and preventing autoimmune Addison's disease lies in improving our understanding of the predisposing factors, the mechanisms responsible for the progression of the disease, and the interactions between adrenal antigens and effector cells and molecules of the immune system. The aim of the present review is to summarize the current knowledge on the role of T cells and cellular immunity in the pathogenesis of autoimmune Addison's disease.

Autoimmune polyendocrine syndromes: clues to type 1 diabetes pathogenesis

Autoimmune diseases such as type 1 diabetes are complex in their pathogenesis. One approach to improving our understanding of type 1 diabetes is the study of diseases that represent more extreme examples of autoimmunity. Autoimmune polyendocrine syndromes (APS) are relatively rare diseases that often include type 1 diabetes as part of the disease phenotype. Recently, there has been tremendous progress in unraveling some of the underlying mechanisms of APS. Here, we highlight the APS disorders with the perspective of the clues they can offer to the pathogenesis and treatment of type 1 diabetes.