AIRE genetic variants and predisposition to polygenic autoimmune disease: The case of Graves' disease and a systematic literature review

Genetic Polymorphisms in Exon 5 and Intron 5 and 7 of AIRE Are Associated with Rheumatoid Arthritis Risk in a Hungarian Population

BACKGROUND

Rheumatoid arthritis (RA) is chronically persistent synovitis and systemic inflammation. Although multiple contributors are detected, only one is pivotal in the neonatal period: the negative selection of autoimmune naïve T-cells by the autoimmune regulator (AIRE) transcriptional factor.

METHODS

Single-nucleotide polymorphisms (SNPs) in the DNA-binding site of AIRE may determine its function and expression. We intended to analyse site-specific allelic polymorphisms in two exon (rs878081 and rs1055311) and three intron (rs1003853, rs2075876, and rs1003854) loci with an RA risk. Our analytical case-control study analysed 270 RA patients and 322 control subjects in five different genetic models using quantitative real-time PCR (qPCR) with TaqMan® assays.

RESULTS

Statistically significant differences were found between the odds of allelic polymorphisms in the loci of rs878081, rs1003854, and rs1003853 among the controls and RA patients, and the disease activity seemed to be significantly associated with the genotypic subgroups of rs878081 and rs1055311. Our in silico analysis supported this, suggesting that allele-specific alterations in the binding affinity of transcriptional factor families might determine RA activity.

CONCLUSION

Our findings highlight the involvement of neonatal self-tolerance in RA pathogenesis, providing novel insights into disease development and paving the way for an analysis of further site-specific genetic polymorphisms in AIRE to expand the intervention time for RA.

Extrathymic AIRE-expressing cells: Friends or foes in autoimmunity and cancer?

Auto-immune regulator (AIRE) is a transcription factor that is mainly known for its crucial role in the thymus. Here, AIRE ensures central tolerance by promoting the expression of peripheral tissue antigens in thymic epithelial cells, which is essential for the negative selection of autoreactive T cells. Intriguingly, AIRE expressing cells have recently been identified in other tissues outside the thymus as well. However, the exact function of these extrathymic AIRE expressing cells (eTACs) remains largely enigmatic. Human eTACs are mainly found in secondary lymphoid tissues under homeostatic conditions, but are also found in pathologies such as the inflamed tissues of patients with autoimmune diseases and in various cancer tissues. eTACs have been demonstrated to express dendritic cell (DC)-like markers, such as MHCII, CD40 and CD127, but also CCR7, IDO and PD-L1. Interestingly, eTACs lack high expression of co-stimulatory molecules, such as CD80 or CD86. In mice, different types of peripheral AIRE expressing cells have been described, including cells with an innate lymphoid cell-like phenotype and antigen presenting cell (APC) function. These findings suggest that eTACs are APCs with the possibility to modulate or inhibit immune responses, which is confirmed by functional murine studies demonstrating the ability of eTACs to induce tolerance in autoreactive T cells. The potential immunomodulatory function of eTACs makes them promising targets to restore tolerance in autoimmunity or improve immunotherapy in cancer settings. Yet, this requires a better understanding of these cells and the molecular mechanisms involved. In this review we aim to summarize the current knowledge and understanding of eTACs, including their putative roles in health and disease.

In Search for the Missing Link in APECED-like Conditions: Analysis of the AIRE Gene in a Series of 48 Patients

Autoimmune diseases are a heterogeneous group of disorders of the immune system. They can cluster in the same individual, revealing various preferential associations for polyendocrine autoimmune syndromes. Clinical observation, together with advances in genetics and the understanding of pathophysiological processes, has further highlighted that autoimmunity can be associated with immunodeficiency; autoimmunity may even be the first primary immunodeficiency manifestation. Analysis of susceptibility genes for the development of these complex phenotypes is a fundamental issue. In this manuscript, we revised the clinical and immunologic features and the presence of AIRE gene variations in a cohort of 48 patients affected by high polyautoimmunity complexity, i.e., APECED-like conditions, also including patients affected by primary immunodeficiency. Our results evidenced a significant association of the S278R polymorphism of the AIRE gene with APECED-like conditions, including both patients affected by autoimmunity and immunodeficiency and patients with polyautoimmunity compared to healthy controls. A trend of association was also observed with the IVS9+6 G>A polymorphism. The results of this genetic analysis emphasize the need to look for additional genetic determinants playing in concert with AIRE polymorphisms. This will help to improve the diagnostic workup and ensure a precision medicine approach to targeted therapies in APECED-like patients.

Autoimmunity in Primary Immunodeficiencies (PID)

Primary immunodeficiency (PID) may impact any component of the immune system. The number of PID and immune dysregulation disorders is growing steadily with advancing genetic detection methods. These expansive recognition methods have changed the way we characterize PID. While PID were once characterized by their susceptibility to infection, the increase in genetic analysis has elucidated the intertwined relationship between PID and non-infectious manifestations including autoimmunity. The defects permitting opportunistic infections to take hold may also lead the way to the development of autoimmune disease. In some cases, it is the non-infectious complications that may be the presenting sign of PID autoimmune diseases, such as autoimmune cytopenia, enteropathy, endocrinopathies, and arthritis among others, have been reported in PID. While autoimmunity may occur with any PID, this review will look at certain immunodeficiencies most often associated with autoimmunity, as well as their diagnosis and management strategies.

Autoimmune Regulator Gene Polymorphisms in Egyptian Systemic Lupus Erythematosus Patients: Preliminary Results

Background

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease. The autoimmune regulator (AIRE) is a master regulator of self-tolerance development. AIRE mutations lead to the development of autoimmune polyglandular syndrome type 1 while AIRE polymorphisms have been linked to organ-specific autoimmunity. The study is aimed at addressing the association between AIRE polymorphisms, rs2075876 (G > A) and rs760426 (A > G), and SLE susceptibility and expression in Egyptian patients.

Methods

Ninety-nine patients were included. One hundred and ten, and 123 control subjects were genotyped for rs2075876 and rs760426, respectively. Lupus severity was assessed using the Lupus Severity of Disease Index and Lupus Severity Index (LSI). Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology (ACR) damage index was considered. Genotyping was done using StepOne Real-Time PCR. Results. AIRE rs760426 GG was more frequent in the patients under the genotype level (14.1% vs. 4.9%, p = 0.032) and recessive model (14.1% vs. 4.9%, p = 0.017, OR = 3.2 (1.2-8.7)). Musculoskeletal involvement and nephritis were associated with AIRE rs2075876 under the dominant (97.9% vs. 80.8%, p = 0.009, OR = 11 (1.3-89.2)) and recessive models (100% vs. 69.3%, p = 0.032), respectively; and both were linked to AIRE rs2075876 at the allelic level: 98.3% vs. 85%, p = 0.005, OR = 10.1 (1.3-76.6) and 82.8% vs. 68.6, p = 0.041, OR = 2.2 (1-4.7), respectively. Patients with AIRE rs2075876 A alleles had a higher damage index ( 1 ± 1.3 vs. 0.6 ± 1.1, p = 0.045) while the LSI was greater in patients with AIRE rs2075876 (8.5 ± 0.5 vs. 7.8 ± 1.3, p = 0.002) and rs760426 (8.6 ± 11 vs. 7.8 ± 1.2, p = 0.031) under the recessive models. Conclusion. AIRE rs760426 could share in SLE susceptibility while AIRE rs2075876 could influence the disease expression and burden in Egyptian patients.

Current and Future Therapeutic Approaches for Thymic Stromal Cell Defects

Inborn errors of thymic stromal cell development and function lead to impaired T-cell development resulting in a susceptibility to opportunistic infections and autoimmunity. In their most severe form, congenital athymia, these disorders are life-threatening if left untreated. Athymia is rare and is typically associated with complete DiGeorge syndrome, which has multiple genetic and environmental etiologies. It is also found in rare cases of T-cell lymphopenia due to Nude SCID and Otofaciocervical Syndrome type 2, or in the context of genetically undefined defects. This group of disorders cannot be corrected by hematopoietic stem cell transplantation, but upon timely recognition as thymic defects, can successfully be treated by thymus transplantation using cultured postnatal thymic tissue with the generation of naïve T-cells showing a diverse repertoire. Mortality after this treatment usually occurs before immune reconstitution and is mainly associated with infections most often acquired pre-transplantation. In this review, we will discuss the current approaches to the diagnosis and management of thymic stromal cell defects, in particular those resulting in athymia. We will discuss the impact of the expanding implementation of newborn screening for T-cell lymphopenia, in combination with next generation sequencing, as well as the role of novel diagnostic tools distinguishing between hematopoietic and thymic stromal cell defects in facilitating the early consideration for thymus transplantation of an increasing number of patients and disorders. Immune reconstitution after the current treatment is usually incomplete with relatively common inflammatory and autoimmune complications, emphasizing the importance for improving strategies for thymus replacement therapy by optimizing the current use of postnatal thymus tissue and developing new approaches using engineered thymus tissue.

Association of AIRE (rs2075876), but not CTLA4 (rs231775) polymorphisms with systemic lupus erythematosus

BACKGROUND

The AIRE (rs2075876) and CTLA4 (rs231775) variants have a crucial function in controlling the negative selection and suppression of T lymphocytes. Numerous reports studied the association of AIRE and CTLA4 variants with different autoimmune disorders, but with inconclusive conclusions. The main purpose of this work is to evaluate the association of these two variants with SLE susceptibility among Egyptian patients.

SUBJECTS AND METHODS

A total of 247 participants (100 SLE patients and 147 healthy controls) were enrolled in this case-controlled study. The genomic DNA of these dual variants was genotyped using the TaqMan genotyping method.

RESULTS

The AIRE (rs2075876) variant conferred protection against developing SLE disease under allelic [A allele vs. G allele; OR = 0.16, 95%CI = 0.09-0.28], and dominant [GA + AA vs. GG; OR = 0.14, 95%CI = 0.05-0.34] models. Moreover, patients with AIRE rs2075876 (A/A) genotype revealed a statistically significant with lower levels of complement 3 (p-value = 0.007). Nonetheless, the CTLA4 (rs231775) variant was not associated with increased risk of SLE under all genetic association models (p-value > 0.05). However, CTLA4 rs231775 (G/G) genotype observed significant difference with recurrent infection and hematuria.

CONCLUSIONS

Our findings indicated that the AIRE (rs2075876) variant conferred protection against developing SLE disease, but not the CTLA4 (rs231775) variant.

Association of autoimmune regulator gene polymorphism with susceptibility to rheumatoid arthritis in Egyptian population

The autoimmune regulator (AIRE) gene controls autoimmunity via its transcript AIRE protein that suppresses naïve T cells during central selection. The role of AIRE polymorphism in rheumatoid arthritis (RA) autoimmunity remains elusive. This study aimed to investigate the association of two selected SNPs, namely, rs760426 and rs2075876, with RA susceptibility in the Suez Canal Zone population. The study population included 100 RA patients, and the control group included 100 healthy subjects who were age- and sex-matched to the RA group. SNP genotyping was performed using real-time polymerase chain reaction-based allelic discrimination assay, the odds ratio was defined to assess the strength of the association. For rs760426, combining genotypes data revealed a significant increase for A/G genotype in the RA cases (47%, n = 47) than in the control group (27%, n = 27) in both co-dominant and over-dominant models (P = 0.013 and 0.003 respectively). In addition, rs760426 correlated to duration of RA (P = 0.031) and anti-cyclic citrullinated peptide antibody (P = 0.021). For rs2075876, there was a significant increase in the A/A genotype in RA patients compared with control subjects. In the co-dominant model, the frequency of A/A was 14% and 7% respectively (P = 0.02). In contrast to rs760426, rs2075876 associated with the risk of increased body mass index (P = 0.014) and the positivity of rheumatoid factor (RF) (P = 0.043). The frequency of minor alleles, G allele in rs760426 SNP, and A allele in rs2075876 was higher in RA patients than in control. The haplotype frequency of both G and A alleles in rs760426 and rs2075876 receptively was 11% in RA group with statistically significant difference (P = <0.001) between RA patients and healthy control. SNPs rs760426 and rs2075876 in the AIRE gene may contribute to the risk for RA susceptibility. These two polymorphisms were associated with variable risk factors and predictive biomarkers for RA. The mutant allele (G) of rs760426 SNP has significant indication of poor prognosis.

Primary immunodeficiency and autoimmunity: A comprehensive review

The primary immunodeficiency diseases (PIDs) include many genetic disorders that affect different components of the innate and adaptive responses. The number of distinct genetic PIDs has increased exponentially with improved methods of detection and advanced laboratory methodology. Patients with PIDs have an increased susceptibility to infectious diseases and non-infectious complications including allergies, malignancies and autoimmune diseases (ADs), the latter being the first manifestation of PIDs in several cases. There are two types of PIDS. Monogenic immunodeficiencies due to mutations in genes involved in immunological tolerance that increase the predisposition to develop autoimmunity including polyautoimmunity, and polygenic immunodeficiencies characterized by a heterogeneous clinical presentation that can be explained by a complex pathophysiology and which may have a multifactorial etiology. The high prevalence of ADs in PIDs demonstrates the intricate relationships between the mechanisms of these two conditions. Defects in central and peripheral tolerance, including mutations in AIRE and T regulatory cells respectively, are thought to be crucial in the development of ADs in these patients. In fact, pathology that leads to PID often also impacts the Treg/Th17 balance that may ease the appearance of a proinflammatory environment, increasing the odds for the development of autoimmunity. Furthermore, the influence of chronic and recurrent infections through molecular mimicry, bystander activation and super antigens activation are supposed to be pivotal for the development of autoimmunity. These multiple mechanisms are associated with diverse clinical subphenotypes that hinders an accurate diagnosis in clinical settings, and in some cases, may delay the selection of suitable pharmacological therapies. Herein, a comprehensively appraisal of the common mechanisms among these conditions, together with clinical pearls for treatment and diagnosis is presented.

The rs878081 polymorphism of AIRE gene increases the risk of rheumatoid arthritis in a Chinese Han population: a case-control study

The autoimmune regulator (AIRE), a transcriptional regulator expressed in medullary thymic epithelial cells, plays an important role in thymocyte education and negative selection. Several citations studying the association between the rs878081 exon polymorphism of the AIRE gene and the risk of rheumatoid arthritis (RA) in different populations have yielded conflicting findings. Thus, this case-control study involving 300 RA cases and 300 controls was aimed to identify whether such association existed in a Chinese Han population from East China. The rs878081 polymorphism of the AIRE gene was genotyped. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using the chi-squared test, genetic model analysis, and stratification analysis. Genetic model analysis showed significant correlations between the TT genotype and the risk of RA (OR: 1.89, 95%CI: 1.03-3.47 in TT vs CC; OR: 1.84, 95%CI: 1.02-3.31 in TT vs CC+TC). Stratification analyses of sex, age, smoking, and alcoholism suggested that the rs878081 polymorphism of the AIRE gene increased RA risk among non-smokers. In conclusion, rs878081 polymorphism of AIRE gene increases the risk of RA in a Chinese Han population.

Association of AIRE Polymorphism and the Susceptibility to Multiple Sclerosis in Iranian Population

Background:

Multiple Sclerosis (MS) is the most common cause of neurologic disability in young adults. Recently, the AIRE gene was identified as a genetic risk factor for several autoimmune diseases in genome wide association studies. The aim of this study was to further investigate the possible role of the AIRE gene in susceptibility to MS in Iranian population.

Methods:

A total of 112 MS patients and 94 ethnically matched controls were included in the study. The Single-Nucleotide Polymorphism (SNP) (rs1800520, C>G) with a global MAF=0.2282/1143 was selected and genotyped using HRM real-time PCR method.

Results:

Results showed that AIRE SNP rs1800520 was significantly less common in the MS patients than in healthy controls (17.8 vs. 28.7%, pc=0.032, OR=0.54,95% CI 0.279, 1.042). Also, the frequency of allele G was significantly higher among the control group than in the case group (37.77 vs. 25%, pc=0.014). Interestingly, mRNA transcribed on the rs1800520 SNP showed decreased free energy than the wild type suggesting that its increased stability may be responsible for the different activities of the polymorphic AIRE molecule.

Conclusions:

This is the first study investigating the relationship between AIRE gene and the susceptibility to MS. These results indicated that the rs1800520 SNP is not a susceptibility gene variant for the development of MS in Iranian population.

Association between AIRE gene polymorphism and rheumatoid arthritis: a systematic review and meta-analysis of case-control studies

Autoimmune regulator (AIRE) is a transcription factor that functions as a novel player in immunological investigations. In the thymus, it has a pivotal role in the negative selection of naive T-cells during central tolerance. Experimental studies have shown that single nucleotide polymorphism (SNP) alters transcription of the AIRE gene. SNPs thereby provide a less efficient negative selection, propagate higher survival of autoimmune T-cells, and elevate susceptibility to autoimmune diseases. To date, only rheumatoid arthritis (RA) has been analysed by epidemiological investigations in relation to SNPs in AIRE. In our meta-analysis, we sought to encompass case-control studies and confirm that the association between SNP occurrence and RA. After robust searches of Embase, PubMed, Cochrane Library, and Web of Science databases, we found 19 articles that included five independent studies. Out of 11 polymorphisms, two (rs2075876, rs760426) were common in the five case-control studies. Thus, we performed a meta-analysis for rs2075876 (7145 cases and 8579 controls) and rs760426 (6696 cases and 8164 controls). Our results prove that rs2075876 and rs760426 are significantly associated with an increased risk of RA in allelic, dominant, recessive, codominant heterozygous, and codominant homozygous genetic models. These findings are primarily based on data from Asian populations.

Is Graves' disease a primary immunodeficiency? New immunological perspectives on an endocrine disease

BACKGROUND

Uncertainty about factors influencing the susceptibility and triggers for Graves' disease persists, along with a wide variation in the response to anti-thyroid drugs, currently at approximately 50% of non-responders. The aim of this narrative review is to summarize immunological concepts, with a combined endocrine and immunological perspective, to highlight potential new areas of research.

MAIN TEXT

Relevant studies were identified through a systematic literature search using the PubMed and EMBASE databases in March 2016. No cut-offs regarding dates were imposed. We used the terms "Graves' Disease" or "Basedow" or "thyrotoxicosis" together with the terms "etiology", "pathophysiology", "immunodeficiency", "causality", and "autoimmunity". The terms "orbitopathy", "ophthalmopathy", and "amiodarone" were excluded. Articles in English, French, German, Croatian, Spanish, and Italian were eligible for inclusion.

CONCLUSIONS

While concepts such as the impact of iodine, smoking, human leucocyte antigen, infections, and ethnicity are established, new ideas have emerged. Pertaining evidence suggests the involvement of autoimmunity and immunodeficiency in the pathophysiology of Graves' disease. Recent studies point to specific immunological mechanisms triggering the onset of disease, which may also serve as targets for more specific therapies.

A single nucleotide polymorphism of AIRE gene located in the 21q22.3 increases the risk of rheumatoid arthritis

Several studies addressed the association of autoimmune regulator (AIRE) gene polymorphism with the risk of rheumatoid arthritis (RA); however, their conclusions were inconsistent. For better investigating the effects of this polymorphism on the risk of RA, we conducted this study to evaluate the role of AIRE rs2075786 polymorphism in the risk of RA. Four eligible studies involving 6,755 cases and 7,970 controls were identified by searching the databases of PubMed, CNKI and EMBASE up to February 2017. Our study revealed that AIRE rs2075786 polymorphism was associated with an increased risk of RA under all genetic models. In the subgroup analysis, AIRE rs2075786 polymorphism contributed to RA susceptibility among Asians, but not among Caucasians. To summarize,, this meta-analysis confirms that AIRE rs2075786 polymorphism may play a significant role in increasing the risk of RA. Stratification analysis by ethnicity reveals that AIRE rs2075786 polymorphism is associated with an increased risk of RA among Asians, but not among Caucasians. These findings need further validation in the large multicenter case-control studies.

AIRE-mutations and autoimmune disease

The gene causing the severe organ-specific autoimmune disease autoimmune polyendocrine syndrome type-1 (APS-1) was identified in 1997 and named autoimmune regulator (AIRE). AIRE plays a key role in shaping central immunological tolerance by facilitating negative selection of T cells in the thymus, building the thymic microarchitecture, and inducing a specific subset of regulatory T cells. So far, about 100 mutations have been identified. Recent advances suggest that certain mutations located in the SAND and PHD1 domains exert a dominant negative effect on wild type AIRE resulting in milder seemingly common forms of autoimmune diseases, including pernicious anemia, vitiligo and autoimmune thyroid disease. These findings indicate that AIRE also contribute to autoimmunity in more common organ-specific autoimmune disorders.