The immunobiology and clinical features of type 1 autoimmune polyglandular syndrome (APS-1)

An uncommon presentation of autoimmune polyglandular syndrome type 1 (APS-1)-A case report

Key Clinical Message

Autoimmune polyglandular syndrome type 1 (APS-1) is a rare disorder defined by the presence of at least two of the following conditions: chronic mucocutaneous candidiasis (CMC), chronic hypoparathyroidism, and Addison's syndrome. Despite the lack of CMC and autoimmune history, APS-1 can be diagnosed using genetic testing.

We present the case of a 28-year-old female patient with a history of hypocalcemia due to hypoparathyroidism since the age of 2 years. She presented to the endocrine clinic with hypogonadism, primary amenorrhea, and primary ovarian insufficiency. Addison's disease was eventually diagnosed, despite a negative Synacthen test. The adrenal crisis required intravenous hydrocortisone therapy. No CMC was documented, and there was no family history of such conditions. The diagnosis of APS-1 was confirmed by genetic testing, revealing homozygous pathogenic variants of the autoimmune regulator gene. Management included oral calcium and calcitriol and oral hydrocortisone and fludrocortisone for Addison's disease. Hormonal induction of secondary sexual characteristics was initiated. The patient received combined oral estrogen and progesterone pills. This case highlights the critical significance of early recognition, thorough evaluation, and tailored treatment for patients with APS-1 to enhance their quality of life and mitigate potentially life-threatening complications. This underscores the importance of screening for associated minor autoimmune diseases as part of a holistic approach to care.

Exploring Chronic Hypocalcemia: Insights into Autoimmune Polyglandular Syndrome Type 1-A Case Study and Literature Review

Hypocalcemia is a common occurrence in pediatric patients, attributed to various causes and presenting with diverse clinical manifestations. A prompt evaluation is necessary to determine its underlying cause, whether it presents acutely or chronically, and to tailor treatment based on its severity. Among the potential causes of chronic hypocalcemia, primary hypoparathyroidism stands out. The case of a seven-year-old male patient with hypocalcemia reported in this article serves as an illustration, wherein targeted next-generation sequencing revealed a homozygous p.R257X mutation in the AIRE gene, indicative of autoimmune polyendocrine syndrome type 1 (APS-1). It poses challenges due to its multisystemic nature and involvement of specific autoantibodies, often leading to underdiagnosis, owing to its rarity, varied manifestations, and incomplete penetrance. A comprehensive review of the APS-1 literature was conducted to provide insights into the clinical manifestations, genetic spectrum, potential immunological mechanisms, and current medical strategies. Additionally, the recognition of AIRE gene mutations is crucial for facilitating genetic diagnosis, prognosis, and potential treatment strategies for APS-1. The management of such cases involves individualized approaches to treatment, regular monitoring, medication adjustments, and the early identification of associated conditions.

Novel homozygous mutations in AIRE leading to APS-1 and potential mechanisms based on bioinformatics analysis

Background

Autoimmune Poly-endocrine Syndrome Type 1 (APS-1), also known as autoimmune poly-endocrinopathy-candidiasis-ectodermal dystrophy (APECED), is a single-gene hereditary disorder usually characterized by chronic mucocutaneous candidiasis, hypoparathyroidism, and autoimmune adrenocortical insufficiency. This syndrome is very rare in China.

Methods

For our reported patient, we employed clinical and laboratory examinations along with genetic identification. For previously reported cases, we summarized findings based on meta-analysis principles. To investigate the AIRE gene's role in disease, we utilized bioinformatics analysis with existing databases and R language processing.

Results

Nucleotide sequence analysis revealed two novel homozygous missense mutations (c.74C > G; c.1612C > T) in the patient's AIRE gene, confirming APS-1 diagnosis. The 3D structure of these mutation sites was described for the first time, showing that altered side chains could affect AIRE protein function. We analyzed 16 genetically diagnosed APS-1 Chinese patients, summarized the AIRE genetic spectrum, and found that exons 1, 2, 3, and 5 were most commonly affected. Hypoparathyroidism and adrenal insufficiency were the most common clinical manifestations (56%-93%), followed by hypothyroidism (31.25%), hypogonadism (12.5%), type 2 diabetes (6.25%), and type 1 diabetes (6.25%). Bioinformatics analysis indicated that AIRE mutations cause antigen presentation abnormalities in immune cells, leading to excessive endogenous and reduced exogenous antigen presentation.

Conclusions

Our study summarized the clinical features of APS-1 caused by AIRE gene mutations and explored underlying mechanisms. For some patients, the prophylactic use of antimicrobial agents may be beneficial. These findings guide early genetic screening and inform potential research directions for treatment strategies.

Leber congenital amaurosis as the initial and essential manifestation in a Chinese patient with autoimmune polyglandular syndrome Type 1

PURPOSE

Autoimmune polyglandular syndrome Type 1 (APS-1) is a rare autosomal recessive disorder caused by defects in the autoimmune regulator (AIRE) gene. Patients are generally diagnosed at ages between five and fifteen years when they exhibit three or more manifestations, most typically mucocutaneous candidiasis, autoimmune Addison's disease, and hypoparathyroidism. Our study aims to report the first case of a Chinese APS-1 patient, presented with LCA as the initial and essential clinical feature of this rare syndrome.

METHODS

Detailed medical and family history were recorded for the patient. Also, the comprehensive ophthalmological examinations were conducted. Whole exome sequencing (WES) was applied to screen pathogenic variants. Sanger sequencing validation and segregation analysis were further performed for confirmation.

RESULTS

A 3-year-old boy with severely impaired vision and initially referred as LCA. However, with a detailed history review, oral candidiasis, dental enamel hypoplasia, and nail candida infection were revealed. Moreover, genetic analysis revealed the homozygous c.769C>T (p.R257X) in AIRE gene (NM_000383.3) as the causative variant.

CONCLUSION

We presented one case diagnosed with APS-1 based on clinical characteristics and genetic analysis. Our study demonstrated that LCA could serve as a warning sign for APS-1 and a potential trigger of early screening, which might prevent life-threatening complications.

Challenges in establishing animal models for studying osteoimmunology of hypoparathyroidism

Hypoparathyroidism is a relatively rare human and veterinary disease characterized by deficient or absent production of parathyroid hormone (PTH). PTH is known as a classical regulator of calcium and phosphorus homeostasis. Nevertheless, the hormone also appears to modulate immune functions. For example, increased CD4:CD8 T-cell ratios and elevated interleukin (IL)-6 and IL-17A levels were observed in patients with hyperparathyroidism, whereas gene expression of tumor necrosis factor-α (TNF-α) and granulocyte macrophage-colony stimulating factor (GM-CSF) was decreased in patients with chronic postsurgical hypoparathyroidism. Various immune cell populations are affected differently. So, there is a need for validated animal models for the further characterization of this disease for identifying targeted immune-modulatory therapies. In addition to genetically modified mouse models of hypoparathyroidism, there are surgical rodent models. Parathyroidectomy (PTX) can be well performed in rats-for pharmacological and associated osteoimmunological research and bone mechanical studies, a large animal model could be preferable, however. A major drawback for successfully performing total PTX in large animal species (pigs and sheep) is the presence of accessory glands, thus demanding to develop new approaches for real-time detection of all parathyroid tissues.

Rare forms of genetic paediatric adrenal insufficiency: Excluding congenital adrenal hyperplasia

Adrenal insufficiency (AI) is a severe endocrine disorder characterized by insufficient glucocorticoid (GC) and/or mineralocorticoid (MC) secretion by the adrenal glands, due to impaired adrenal function (primary adrenal insufficiency, PAI) or to insufficient adrenal stimulation by pituitary ACTH (secondary adrenal insufficiency, SAI) or tertiary adrenal insufficiency due to hypothalamic dysfunction. In this review, we describe rare genetic causes of PAI with isolated GC or combined GC and MC deficiencies and we also describe rare syndromes of isolated MC deficiency. In children, the most frequent cause of PAI is congenital adrenal hyperplasia (CAH), a group of adrenal disorders related to steroidogenic enzyme deficiencies, which will not be included in this review. Less frequently, several rare diseases can cause PAI, either affecting exclusively the adrenal glands or with systemic involvement. The diagnosis of these diseases is often challenging, due to the heterogeneity of their clinical presentation and to their rarity. Therefore, the current review aims to provide an overview on these rare genetic forms of paediatric PAI, offering a review of genetic and clinical features and a summary of diagnostic and therapeutic approaches, promoting awareness among practitioners, and favoring early diagnosis and optimal clinical management in suspect cases.

Autoimmune Polyendocrine Syndromes in the Pediatric Age

Autoimmune polyendocrine syndromes (APSs) encompass a heterogeneous group of rare diseases characterized by autoimmune activity against two or more endocrine or non-endocrine organs. Three types of APSs are reported, including both monogenic and multifactorial, heterogeneous disorders. The aim of this manuscript is to present the main clinical and epidemiological characteristics of APS-1, APS-2, and IPEX syndrome in the pediatric age, describing the mechanisms of autoimmunity and the currently available treatments for these rare conditions.

Selected Genetic Factors Associated with Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) is a heterogeneous disease resulting from non-functional ovaries in women before the age of 40. It is characterized by primary amenorrhea or secondary amenorrhea. As regards its etiology, although many POI cases are idiopathic, menopausal age is a heritable trait and genetic factors play an important role in all POI cases with known causes, accounting for approximately 20% to 25% of cases. This paper reviews the selected genetic causes implicated in POI and examines their pathogenic mechanisms to show the crucial role of genetic effects on POI. The genetic factors that can be found in POI cases include chromosomal abnormalities (e.g., X chromosomal aneuploidies, structural X chromosomal abnormalities, X-autosome translocations, and autosomal variations), single gene mutations (e.g., newborn ovary homeobox gene (NOBOX), folliculogenesis specific bHLH transcription factor (FIGLA), follicle-stimulating hormone receptor (FSHR), forkhead box L2 (FOXL2), bone morphogenetic protein 15 (BMP15), etc., as well as defects in mitochondrial functions and non-coding RNAs (small ncRNAs and long ncRNAs). These findings are beneficial for doctors to diagnose idiopathic POI cases and predict the risk of POI in women.

Beyond skin white spots: Vitiligo and associated comorbidities

Vitiligo is a common depigmentation disorder of an unknown origin characterized by the selective loss of melanocytes, resulting in typical white macules and patches. However, vitiligo is now recognized as more than just a skin disease, what a dermatologist observes as a white spot of skin is just the "tip of the iceberg" of the condition. We attempt to clarify the classification of comorbidities associated with vitiligo from various reviews and reports, and describe their possible pathogenesis. In conclusion, the literature provides evidence of an association between vitiligo and ocular and auditory abnormalities, autoimmune disorders, other dermatological diseases, metabolic syndrome and related disorders, and psychological diseases. These associations highlight the importance of a multidisciplinary approach in managing vitiligo patients.

Diagnostic Accuracy of Methods for Detection of Antibodies against Type I Interferons in Patients with Endocrine Disorders

Autoantibodies against type 1 interferons (IFN-I) are a highly specific marker for type 1 autoimmune polyglandular syndrome (APS-1). Moreover, determination of antibodies to omega-interferon (IFN-ω) and alpha2-interferon (IFN-α2) allows a short-term diagnosis in patients with isolated and atypical forms of APS-1. In this study, a comparison of three different methods, namely multiplex microarray-based, cell-based and enzyme-linked immunosorbent assays for detection of antibodies against omega-interferon and alpha2-interferon, was carried out. A total of 206 serum samples from adult patients with APS-1, APS-2, isolated autoimmune endocrine pathologies or non-autoimmune endocrine disorders, and healthy individuals were analyzed. In the APS-1 patient cohort (n = 18), there was good agreement between the results of anti-IFN-I antibody tests performed by three methods, with 100% specificity and sensitivity for microarray-based assay. Although only the cell-based assay can determine the neutralizing activity of autoantibodies, the microarray-based assay can serve as a highly specific and sensitive screening test to identify anti-IFN-I antibody positive patients.

A novel AIRE mutation leads to autoimmune polyendocrine syndrome type-1

Autoimmune polyendocrine syndrome type-1 (APS-1) is a rare inherited monogenic autoimmune disease characterized by the presence of at least two of three following major clinical features: chronic mucocutaneous candidiasis, hypoparathyroidism, and adrenal insufficiency. Mutations in autoimmune regulator (AIRE) gene have been found to contribute to APS-1. In the present study, we reported a 36-years-old male APS-1 patient who presented with hypoparathyroidism and Addison’s disease. The proband underwent complete clinical examinations and mutation screening was performed by Sanger sequencing on AIRE gene. A novel homozygous mutation in exon 9 of the AIRE gene (c.1024C>T) was identified. Based on sequencing findings, HEK293T cell-based assays were conducted to analyze the subcellular localization and mutant transcript processing. Our results revealed that p.Q342X mutant localized in nuclear speckles and exerted a dominant-negative effect on wildtype AIRE function. We reported the c.1024C>T mutation of AIRE gene for the first time, which enriched the AIRE mutation database and contributed to further understanding of APS-1.

Autoimmune polyendocrine syndrome type 1: Clinical manifestations, pathogenetic features, and management approach

Autoimmune polyendocrine syndrome type 1 (APS-1) is an autosomal recessive hereditary pathology that develops with endocrine and non-endocrine manifestations in childhood. The classic triad of APS-1 includes chronic candidiasis of the skin and mucous membranes, adrenal insufficiency, and hypoparathyroidism. APS-1 is often accompanied by hypogonadism, type 1 diabetes, autoimmune thyroiditis, vitiligo, alopecia, asplenia, pneumonitis, gastritis, pernicious anemia, and intestinal dysfunction, nephritis, and hepatitis. The prevalence rate is highest in genetically isolated populations (up to 1:6500-1:9000). APS-1 occurs because of mutations in the autoimmune regulator (AIRE) gene, leading to a disrupted mechanism of normal antigen expression, the formation of abnormal clones of immune cells, and autoimmune damage to various organs. Analysis of the AIRE gene is the main diagnostic method for early detection of APS-1 and the choice of methods for its treatment. Timely genetic counseling makes it possible to identify the disease early, prescribe appropriate treatment and prevent serious complications. This paper analyzes scientific information characterizing clinical manifestations of autoimmune polyendocrine syndrome type 1 in association with its pathogenetic features, epidemiology, and current management.

Oral manifestations of autoimmune polyglandular syndrome type 1

AIMS

Autoimmune polyglandular syndrome type I (APS-I) is a rare condition of autosomal recessive and monogenic inheritance, which is characterized clinically by at least two signs of the classic triad: mucocutaneous candidosis, hypoparathyroidism, and Addison's disease. This study aims to report the oral manifestations of APS-I in a 42-year-old woman, who attended the Special Care Dentistry Center.

METHODS AND RESULTS

The patient presented with hypoparathyroidism, diabetes mellitus, and autoimmune hepatitis. Chronic hyperplastic candidosis (CHC) was the main oral manifestation and it was diagnosed based on clinical and cytologic characteristics. Microstomia, angular cheilitis, xerostomia, enamel hypoplasia, and microdontia were also present.

CONCLUSIONS

CHC was treated with topical nystatin and oral fluconazole, resulting in a significant improvement of the lesions.

Pathogenic TNF-α drives peripheral nerve inflammation in an Aire-deficient model of autoimmunity

Immune cells infiltrate the peripheral nervous system (PNS) after injury and with autoimmunity, but their net effect is divergent. After injury, immune cells are reparative, while in inflammatory neuropathies (e.g., Guillain Barré Syndrome and chronic inflammatory demyelinating polyneuropathy), immune cells are proinflammatory and promote autoimmune demyelination. An understanding of immune cell phenotypes that distinguish these conditions may, therefore, reveal new therapeutic targets for switching immune cells from an inflammatory role to a reparative state. In an autoimmune regulator (Aire)-deficient mouse model of inflammatory neuropathy, we used single-cell RNA sequencing of sciatic nerves to discover a transcriptionally heterogeneous cellular landscape, including multiple myeloid, innate lymphoid, and lymphoid cell types. Analysis of cell-cell ligand-receptor interactions uncovered a macrophage-mediated tumor necrosis factor-α (TNF-α) signaling axis that is induced by interferon-γ and required for initiation of autoimmune demyelination. Developmental trajectory visualization suggested that TNF-α signaling is associated with metabolic reprogramming of macrophages and polarization of macrophages from a reparative state in injury to a pathogenic, inflammatory state in autoimmunity. Autocrine TNF-α signaling induced macrophage expression of multiple genes (Clec4e, Marcksl1, Cxcl1, and Cxcl10) important in immune cell activation and recruitment. Genetic and antibody-based blockade of TNF-α/TNF-α signaling ameliorated clinical neuropathy, peripheral nerve infiltration, and demyelination, which provides preclinical evidence that the TNF-α axis may be effectively targeted to resolve inflammatory neuropathies.

Molecular and clinical characterization of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) in Iranian non-Jewish patients: report of two novel AIRE gene pathogenic variants

Objective

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) is a rare autosomal recessive systemic autoimmune disease caused by mutations in the autoimmune regulator (AIRE) gene. Incidence of this genetic disorder is estimated at 1/90,000–200,000 worldwide and 1/6500–9000 in genetically isolated populations such as Iran. Here, we investigated AIRE gene mutations in eight independent Iranian non-Jewish families.

Methods

We sequenced the coding regions of the AIRE gene and documented mutations which were further confirmed in respective parents.

Results

In total, 11 cases from 8 independent families were recruited. Mucosal candidiasis, Addison’s disease and hypoparathyroidism were the most common clinical manifestations in these patients. One novel homozygous splice acceptor mutation (c.308-1G>C), and one novel heterozygous stop-gain mutation (c.1496delC) combined with a known heterozygous c.232T>C missense mutation were found. Moreover, we observed previously described splice donor (c.1095+2T>A), frameshift (c.967-979del), stop-gain (c.415C>T), and missense (c.62C>T) mutations among the patients. All results were co-segregated in parents.

Conclusion

Here, we reported two novel mutations in the AIRE gene leading to APECED. Our data could provide insight into the phenotypic and genotypic spectrum of APECED in the non-Jewish Iranian population. These findings, in addition to future functional assays, can elucidate disease-causing mechanisms related to the AIRE gene and assist in genetic counseling and diagnosis.

Treg-associated monogenic autoimmune disorders and gut microbial dysbiosis

Primary immunodeficiency diseases (PIDs) caused by a single-gene defect generally are referred to as monogenic autoimmune disorders. For example, mutations in the transcription factor autoimmune regulator (AIRE) result in a condition called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy; while mutations in forkhead box P3 lead to regulatory T cell (Treg)-deficiency-induced multiorgan inflammation, which in humans is called "immune dysregulation, polyendocrinopathy, enteropathy with X-linked inheritance" (or IPEX syndrome). Previous studies concluded that monogenic diseases are insensitive to commensal microbial regulation because they develop even in germ-free (GF) animals, a conclusion that has limited the number of studies determining the role of microbiota in monogenic PIDs. However, emerging evidence shows that although the onset of the disease is independent of the microbiota, several monogenic PIDs vary in severity in association with the microbiome. In this review, we focus on monogenic PIDs associated with Treg deficiency/dysfunction, summarizing the gut microbial dysbiosis that has been shown to be linked to these diseases. From limited studies, we have gleaned several mechanistic insights that may prove to be of therapeutic importance in the early stages of life. IMPACT: This review paper serves to refute the concept that monogenic PIDs are not linked to the microbiome. The onset of monogenic PIDs is independent of microbiota; single-gene mutations such as AIRE or Foxp3 that affect central or peripheral immune tolerance produce monogenic diseases even in a GF environment. However, the severity and outcome of PIDs are markedly impacted by the microbial composition. We suggest that future research for these conditions may focus on targeting the microbiome.

Autoimmune polyendocrine syndrome type 1: an Italian survey on 158 patients

BACKGROUND

Autoimmune Polyglandular Syndrome type 1 (APS-1) is a rare recessive inherited disease, caused by AutoImmune Regulator (AIRE) gene mutations and characterized by three major manifestations: chronic mucocutaneous candidiasis (CMC), chronic hypoparathyroidism (CH) and Addison's disease (AD).

METHODS

Autoimmune conditions and associated autoantibodies (Abs) were analyzed in 158 Italian patients (103 females and 55 males; F/M 1.9/1) at the onset and during a follow-up of 23.7 ± 15.1 years. AIRE mutations were determined.

RESULTS

The prevalence of APS-1 was 2.6 cases/million (range 0.5-17 in different regions). At the onset 93% of patients presented with one or more components of the classical triad and 7% with other components. At the end of follow-up, 86.1% had CH, 77.2% AD, 74.7% CMC, 49.5% premature menopause, 29.7% autoimmune intestinal dysfunction, 27.8% autoimmune thyroid diseases, 25.9% autoimmune gastritis/pernicious anemia, 25.3% ectodermal dystrophy, 24% alopecia, 21.5% autoimmune hepatitis, 17% vitiligo, 13.3% cholelithiasis, 5.7% connective diseases, 4.4% asplenia, 2.5% celiac disease and 13.9% cancer. Overall, 991 diseases (6.3 diseases/patient) were found. Interferon-ω Abs (IFNωAbs) were positive in 91.1% of patients. Overall mortality was 14.6%. The AIRE mutation R139X was found in 21.3% of tested alleles, R257X in 11.8%, W78R in 11.4%, C322fsX372 in 8.8%, T16M in 6.2%, R203X in 4%, and A21V in 2.9%. Less frequent mutations were present in 12.9%, very rare in 9.6% while no mutations in 11% of the cases.

CONCLUSIONS

In Italy, APS-1 is a rare disorder presenting with the three major manifestations and associated with different AIRE gene mutations. IFNωAbs are markers of APS-1 and other organ-specific autoantibodies are markers of clinical, subclinical or potential autoimmune conditions.

Autoimmunity in Primary Immunodeficiency Disorders: An Updated Review on Pathogenic and Clinical Implications

During the last years, studies investigating the intriguing association between immunodeficiency and autoimmunity led to the discovery of new monogenic disorders, the improvement in the knowledge of the pathogenesis of autoimmunity, and the introduction of targeted treatments. Autoimmunity is observed with particular frequency in patients with primary antibody deficiencies, such as common variable immunodeficiency (CVID) and selective IgA deficiency, but combined immunodeficiency disorders (CIDs) and disorders of innate immunity have also been associated with autoimmunity. Among CIDs, the highest incidence of autoimmunity is described in patients with autoimmune polyendocrine syndrome 1, LRBA, and CTLA-4 deficiency, and in patients with STAT-related disorders. The pathogenesis of autoimmunity in patients with immunodeficiency is far to be fully elucidated. However, altered germ center reactions, impaired central and peripheral lymphocyte negative selection, uncontrolled lymphocyte proliferation, ineffective cytoskeletal function, innate immune defects, and defective clearance of the infectious agents play an important role. In this paper, we review the main immunodeficiencies associated with autoimmunity, focusing on the pathogenic mechanisms responsible for autoimmunity in each condition and on the therapeutic strategies. Moreover, we provide a diagnostic algorithm for the diagnosis of PIDs in patients with autoimmunity.

B Cells and Autoantibodies in AIRE Deficiency

Autoimmune polyendocrine syndrome type 1 (APS-1) is a rare but severe monogenetic autoimmune endocrine disease caused by failure of the Autoimmune Regulator (AIRE). AIRE regulates the negative selection of T cells in the thymus, and the main pathogenic mechanisms are believed to be T cell-mediated, but little is known about the role of B cells. Here, we give an overview of the role of B cells in thymic and peripheral tolerance in APS-1 patients and different AIRE-deficient mouse models. We also look closely into which autoantibodies have been described for this disorder, and their implications. Based on what is known about B cell therapy in other autoimmune disorders, we outline the potential of B cell therapies in APS-1 and highlight the unresolved research questions to be answered.

Sex-specific remodeling of T-cell compartment with aging: Implications for rat susceptibility to central nervous system autoimmune diseases

The incidence of multiple sclerosis (MS) and susceptibility of animals to experimental autoimmune encephalomyelitis (EAE), the most commonly used experimental model of MS, decrease with aging. Generally, autoimmune diseases develop as the ultimate outcome of an imbalance between damaging immune responses against self and regulatory immune responses (keeping the former under control). Thus, in this review the age-related changes possibly underlying this balance were discussed. Specifically, considering the central role of T cells in MS/EAE, the impact of aging on overall functional capacity (reflecting both overall count and individual functional cell properties) of self-reactive conventional T cells (Tcons) and FoxP3+ regulatory T cells (Tregs), as the most potent immunoregulatory/suppressive cells, was analyzed, as well. The analysis encompasses three distinct compartments: thymus (the primary lymphoid organ responsible for the elimination of self-reactive T cells - negative selection and the generation of Tregs, compensating for imperfections of the negative selection), peripheral blood/lymphoid tissues ("afferent" compartment), and brain/spinal cord tissues ("target" compartment). Given that the incidence of MS and susceptibility of animals to EAE are greater in women/females than in age-matched men/males, sex as independent variable was also considered. In conclusion, with aging, sex-specific alterations in the balance of self-reactive Tcons/Tregs are likely to occur not only in the thymus/"afferent" compartment, but also in the "target" compartment, reflecting multifaceted changes in both T-cell types. Their in depth understanding is important not only for envisaging effects of aging, but also for designing interventions to slow-down aging without any adverse effect on incidence of autoimmune diseases.

Preexisting autoantibodies to type I IFNs underlie critical COVID-19 pneumonia in patients with APS-1

Patients with biallelic loss-of-function variants of AIRE suffer from autoimmune polyendocrine syndrome type-1 (APS-1) and produce a broad range of autoantibodies (auto-Abs), including circulating auto-Abs neutralizing most type I interferons (IFNs). These auto-Abs were recently reported to account for at least 10% of cases of life-threatening COVID-19 pneumonia in the general population. We report 22 APS-1 patients from 21 kindreds in seven countries, aged between 8 and 48 yr and infected with SARS-CoV-2 since February 2020. The 21 patients tested had auto-Abs neutralizing IFN-α subtypes and/or IFN-ω; one had anti-IFN-β and another anti-IFN-ε, but none had anti-IFN-κ. Strikingly, 19 patients (86%) were hospitalized for COVID-19 pneumonia, including 15 (68%) admitted to an intensive care unit, 11 (50%) who required mechanical ventilation, and four (18%) who died. Ambulatory disease in three patients (14%) was possibly accounted for by prior or early specific interventions. Preexisting auto-Abs neutralizing type I IFNs in APS-1 patients confer a very high risk of life-threatening COVID-19 pneumonia at any age.

Characterization of the clinical and genetic spectrum of autoimmune polyendocrine syndrome type 1 in Chinese case series

BACKGROUND

Autoimmune polyendocrine syndrome type 1 (APS1) is a hereditary disease caused by mutations in the AIRE gene with both endocrine and non-endocrine organ involvement. The existing data from China are limited, and this study aims to describe the phenotypes and genetic characterization in Chinese APS1 patients. In this single-center, retrospective, observational study, comprehensive endocrine and extra-endocrine manifestations were collected, and genetic analysis in AIRE was conducted in patients with APS1 between the years of 1984 and 2018 at Peking Union Medical College Hospital.

RESULTS

In total, 13 patients from 12 unrelated families were enrolled, seven of whom were female, with hypoparathyroidism, chronic mucocutaneous candidiasis, and Addison's disease being the most frequently observed manifestations. Up to 84.7% presented with two or three of the above-mentioned manifestations, and nearly 4.9 ± 1.8 components presented in patients aged 21.2 ± 7.9 years old. Several less common phenotypes, such as myeloproliferative disease, pure red cell aplasia, renal tubular acidosis, asplenia, autoimmune hepatitis, and ankylosing spondylitis, were also observed in patients. Altogether, seven different AIRE mutations were found in six patients, four of which (K161fs, G208V, A246fs, and L308F) had not been previously reported in patients with APS1.

CONCLUSION

We have provided a comprehensive profile of Chinese patients with APS1, with less commonly observed features being observed in addition to more regularly seen manifestations. Additionally, different AIRE mutations that were observed have expanded the genetic spectrum, which will help with future understanding of the molecular pathogenesis of APS1.

Clinical, immunological, and genetic features in 938 patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED): a systematic review

Background: Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare inborn immune error characterized by a triad of chronic mucocutaneous candidiasis (CMC), hypoparathyroidism (HP), and adrenal insufficiency (ADI).Methods: Literature search was conducted in PubMed, Web of Science, and Scopus databases using related keywords, and included studies were systematically evaluated.Results: We reviewed 938 APECED patients and the classic triad of APECED was detected in 57.3% (460 of 803) of patients. CMC (82.5%) was reported as the earliest, HP (84.2%) as the most prevalent, and ADI (72.2%) as the latest presentation within the classic triad. A broad spectrum of non-triad involvements has also been reported; mainly included ectodermal dystrophy (64.5%), infections (58.7%), gastrointestinal disorders (52.0%), gonadal failure (42.0%), neurologic involvements (36.4%), and ocular manifestations (34.3%). A significant positive correlation was detected between certain tissue-specific autoantibodies and particular manifestations including ADI and HP. Neutralizing autoantibodies were detected in at least 60.0% of patients. Nonsense and/or frameshift insertion-deletion mutations were detected in 73.8% of patients with CMC, 70.9% of patients with HP, and 74.6% of patients with primary ADI.Conclusion: Besides penetrance diversity, our review revealed a diverse affected ethnicity (mainly from Italy followed by Finland and Ireland). APECED can initially present in adolescence as 5.2% of the patients were older than 18 years at the disease onset. According to the variety of clinical conditions, which in the majority of patients appear gradually over time, clinical management deserves a separate analysis.

Report of two siblings with APECED in Serbia: is there a founder effect of c.769C>T AIRE genotype?

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal-dystrophy (APECED) or autoimmune polyglandular syndrome Type 1 is a rare autosomal recessive syndrome. The disorder is caused by mutations in the AIRE (AutoImmune Regulator) gene. According to the classic criteria, clinical diagnosis requires the presence of at least two of three main components: chronic mucocutaneous candidiasis, hypoparathyroidism and primary adrenal insufficiency. Furthermore, patients are often affected by other endocrine or non-endocrine associated autoimmune conditions. The enrichment of the non-classical triad seems to occur differently in different cohorts. Screenings of the population revealed that homozygous AIRE mutations c.769C > T, c.415C > T and c.254A > G have a founder effect in Finnish, Sardinian and Iranian Jew populations respectively.

CASE PRESENTATION

We report here the clinical and genetic characteristics of two new Serbian APECED siblings, one male and one female, actual age of 27 and 24 respectively, born from non-consanguineous parents. Addison's disease was diagnosed in the male at the age of 3.5 and hypoparathyroidism at the age of 4. The female developed hypoparathyroidism at 4 years of age. She presented diffuse alopecia, madarosis, onychomycosis, teeth enamel dysplasia. She further developed Addison's disease at the age of 11 and Hashimoto's thyroiditis at the age of 13.5. She had menarche at the age of 14 but developed autoimmune oophoritis and premature ovarian failure at the age of 16. A treatment with hydrocortisone, fludrocortisone and alfacalcidiol was established for both siblings; L-T4 (levo-thyroxine) for thyroid dysfunction and levonorgestrel and etinilestradiol for POF were also administered to the female. Genetic screening revealed a homozygous c.769C > T (R257X (p.Arg257X)) AIRE mutation. We additionally reviewed the literature on 11 previously published Serbian patients and evaluated the frequency of their main diseases in comparison to Finnish, Sardinian, Turkish, Indian and North/South American cohorts.

CONCLUSION

A founder effect was discovered for the R257X genotype detected in the DNA of 10 homozygous and 2 heterozygous patients. Of note, all Serbian APECED patients were affected by adrenal insufficiency and 10 out of 13 patients presented CMC.

[Genetic predisposition to mucocutaneous fungal infections]

Mucocutaneous fungal infections are common and usually occur in the presence of certain risk factors. However, these infections can occur in patients with no known risk factors. This indicates the presence of an underlying genetic susceptibility to fungi reflecting an innate or adaptive immune deficiency. In this review, we highlight genetic factors that predispose to mucocutaneous fungal infections specially candidiasis and dermatophytosis.

AIRE Gene Mutation Presenting at Age 2 Years With Autoimmune Retinopathy and Steroid-Responsive Acute Liver Failure: A Case Report and Literature Review

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autosomal recessive disorder caused by mutation in the autoimmune regulator (AIRE) gene. Patients usually are diagnosed at ages between 5 and 15 years when they show 3 or more manifestations, most typically mucocutaneous candidiasis, Addison's disease, and hypoparathyroidism. APECED-associated hepatitis (APAH) develops in only 10% to 40% of patients, with severity varying from subclinical chronic active hepatitis to potentially fatal acute liver failure (ALF). Ocular abnormalities are fairly common, most often keratopathy but sometimes retinopathy. Here we report a 2-year-old Japanese girl with an AIRE gene mutation who developed APAH with ALF, preceded by autoimmune retinopathy associated with anti-recoverin antibody before major symptoms suggested a diagnosis of APECED. Intravenous pulse methylprednisolone therapy followed by a corticosteroid combined with azathioprine treatment resolved ALF and achieved control of APAH. To our knowledge, our patient is the youngest reported to have ALF resulting from an AIRE gene mutation. Pulse methylprednisolone induction therapy followed by treatment with corticosteroid plus azathioprine may well be effective in other children with APAH and AIRE gene mutations.

Multiplex Autoantibody Detection in Patients with Autoimmune Polyglandular Syndromes

The diagnosis of autoimmune polyglandular syndrome (APS) types 1/2 is difficult due to their rarity and nonspecific clinical manifestations. APS-1 development can be identified with assays for autoantibodies against cytokines, and APS-2 development with organ-specific antibodies. In this study, a microarray-based multiplex assay was proposed for simultaneous detection of both organ-specific (anti-21-OH, anti-GAD-65, anti-IA2, anti-ICA, anti-TG, and anti-TPO) and APS-1-specific (anti-IFN-ω, anti-IFN-α-2a, and anti-IL-22) autoantibodies. Herein, 206 serum samples from adult patients with APS-1, APS-2, isolated autoimmune endocrine pathologies or non-autoimmune endocrine pathologies and from healthy donors were analyzed. The prevalence of autoantibodies differed among the groups of healthy donors and patients with non-, mono- and multi-endocrine diseases. APS-1 patients were characterized by the presence of at least two specific autoantibodies (specificity 99.5%, sensitivity 100%). Furthermore, in 16 of the 18 patients, the APS-1 assay revealed triple positivity for autoantibodies against IFN-ω, IFN-α-2a and IL-22 (specificity 100%, sensitivity 88.9%). No anti-cytokine autoantibodies were found in the group of patients with non-APS-1 polyendocrine autoimmunity. The accuracy of the microarray-based assay compared to ELISA for organ-specific autoantibodies was 88.8-97.6%. This multiplex assay can be part of the strategy for diagnosing and predicting the development of APS.

Late-onset autoimmune polyendocrine syndrome type 1: a case report and literature review

Autoimmune polyendocrine syndrome type 1 (APS-1), also referred to as autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a rare monogenic disorder, is classically characterized by a triad of chronic mucocutaneous candidiasis, hypoparathyroidism, and primary adrenal insufficiency. The identified causative gene is autoimmune regulator (AIRE), which encodes a critical transcription factor and is essential for self-tolerance. Here, we describe a late-onset Chinese case who presented with symptoms of persistent tetany due to hypocalcemia. Extensive clinical evaluations revealed that the patient manifested beyond the classic triad of the disease, and next-generation sequencing identified a known homozygous AIRE mutation (p.R139X). APS-1 is a rare inherited immunodeficiency disease with high clinical and genetic heterogeneity. By retrospectively analyzing the disease, we comprehensively reviewed the phenotypic features, summarized the genotype spectrum, and discussed the possible immunological mechanisms of the disease to enhance earlier recognition and implement targeted preventive and therapeutic strategies.

Autoimmune polyendocrine syndrome type 1 (APECED) in the Indian population: case report and review of a series of 45 patients

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal-dystrophy (APECED) or autoimmune polyglandular syndrome type 1 (APS-1) is a rare autosomal recessive genetic disease due to mutations in the AIRE (AutoImmune REgulator) gene. The clinical diagnosis is classically based on the presence of at least two of the three main components: chronic mucocutaneous candidiasis, hypoparathyroidism and primary adrenal insufficiency. Patients often suffer from other endocrine or non-endocrine autoimmune conditions throughout life. APECED etiopathogenesis is mediated by T lymphocytes. Autoantibodies against proteins of the affected organs are found in the serum of APECED patients as well as neutralizing antibodies against cytokines. We report here the clinical and genetic characteristics of 45 Indian APECED patients in comparison to Finnish, Sardinian, Turkish and North/South American cohorts from their published results. We also report a new case of APECED of Indian origin, a 2-year old child suffering from chronic mucocutaneous candidiasis since the age of 8 months, with confirmatory AIRE homozygous mutation c.274C > T (p.R92W).

CONCLUSION

With the inherent limitations of a retrospective study, analysis of Indian APECED patients suggested that compared to classic criteria, application of Ferre/Lionakis criteria validated in North/South American patients could help in earlier diagnosis in 3 of 8 (37.5%) patients for whom adequate information for evaluation was available.

Why Do Some People Develop Serious COVID-19 Disease After Infection, While Others Only Exhibit Mild Symptoms?

The year 2020 was a landmark year of a once-in-a-century pandemic of a novel coronavirus, SARS-CoV-2 virus, that led to a rapidly spreading coronavirus disease (COVID-19). The spectrum of disease with SARS-CoV-2 ranges from asymptomatic to mild upper respiratory illness, to moderate to severe disease with respiratory compromise to acute respiratory distress syndrome, multiorgan failure, and death. Early in the pandemic, risk factors were recognized that contributed to more severe disease, but it became evident that individuals and even young people could have severe COVID-19. As we started to understand the immunobiology of COVID-19, it became clearer that the immune responses to SARS-CoV-2 were variable, and in some cases, the excessive inflammatory response contributed to greater morbidity and mortality. In this review, we will explore some of the additional risk factors that appear to contribute to disease severity and enhance our understanding of why some individuals experience more severe COVID-19. Recent advances in genome-wide associations have identified potential candidate genes in certain populations that may modify the host immune responses leading to dysregulated host immunity. Genetic defects of the type I interferon pathway are also linked to a more clinically severe phenotype of COVID-19. Finally, dysregulation of the adaptive immune system may also play a role in the severity and complex clinical course of patients with COVID-19. A better understanding of the host immune responses to SARS-CoV-2 will hopefully lead to new treatment modalities to prevent the poor outcomes of COVID-19 in those individuals with pre-existing risk factors or genetic variants that contribute to the dysregulated host immune responses.

Beyond Bone: Infectious Diseases and Immunity in Parathyroid Disorders

Parathyroid disorders are characterized by alterations in calcium and phosphate homeostasis due to inappropriately high or low levels of parathyroid hormone (PTH). Despite PTH receptor type 1 has been described in almost all immune lineages and calcium signalling has been confirmed as a crucial mediator for immune response, in vitro studies on the physiological interactions between PTH and immunity are conflicting and not representative of the clinical scenarios seen in patients with parathyroid disorders. Infectious diseases are among the main causes of increased morbidity and mortality in patients with secondary hyperparathyroidism and chronic kidney disease. More, immune alterations have been described in primary hyperparathyroidism. Recent studies have unveiled an increased risk of infections also in hypoparathyroidism, suggesting that not only calcium, but also physiological levels of PTH may be necessary for a proper immune response. Finally, calcium/phosphate imbalance could affect negatively the prognosis of infectious diseases. Our review aimed to collect available data on infectious disease prevalence in patients with parathyroid disorders and new evidence on the role of PTH and calcium in determining the increased risk of infections observed in these patients.

What can clinical immunology learn from inborn errors of epigenetic regulators?

The epigenome is at the interface between environmental factors and the genome, regulating gene transcription, DNA repair, and replication. Epigenetic modifications play a crucial role in establishing and maintaining cell identity and are especially crucial for neurology, musculoskeletal integrity, and the function of the immune system. Mutations in genes encoding for the components of the epigenetic machinery lead to the development of distinct disorders, especially involving the central nervous system and host defense. In this review, we focus on the role of epigenetic modifications for the function of the immune system. By studying the immune phenotype of patients with monogenic mutations in components of the epigenetic machinery (inborn errors of epigenetic regulators), we demonstrate the importance of DNA methylation, histone modifications, chromatin remodeling, noncoding RNAs, and mRNA processing for immunity. Moreover, we give a short overview on therapeutic strategies targeting the epigenome.

Acquired pure red cell aplasia and T cell large granular lymphocytic leukaemia in patients with autoimmune polyglandular syndrome type 1

BACKGROUND

Pure red cell aplasia (PRCA) and large granular lymphocytic leukaemia (LGLL) are very rare complications of autoimmune polyendocrine syndrome type 1 (APS1). Here, we report a case of APS1 with PRCA and LGLL. Previous cases were reviewed, and possible mechanisms are discussed.

CASE PRESENTATION

A 31-year-old female presented with anaemia and was diagnosed with PRCA in our centre. She also had hypoparathyroidism for 24 years, premature ovarian failure for 10 years, osteoporosis for 5 years, recurrent pneumonia with bronchiectasis for 4 years and chronic diarrhoea for 1 year. Boosted whole-exome analysis showed AIRE heterozygous mutations, confirming the diagnosis as APS1. LGLL was diagnosed during follow-up. The PRCA responded well to glucocorticoid. treatment CONCLUSION: AIRE is causally related to the development of LGLL and consequent PRCA, which may be due to some immunological mechanisms.

The contribution of thymic tolerance to central nervous system autoimmunity

Autoimmune diseases of the central nervous system (CNS) are associated with high levels of morbidity and economic cost. Research efforts have previously focused on the contribution of the peripheral adaptive and innate immune systems to CNS autoimmunity. However, a failure of thymic negative selection is a necessary step in CNS-reactive T cells escaping into the periphery. Even with defective thymic or peripheral tolerance, the development of CNS inflammation is rare. The reasons underlying this are currently poorly understood. In this review, we examine evidence implicating thymic selection in the pathogenesis of CNS autoimmunity. Animal models suggest that thymic negative selection is an important factor in determining susceptibility to and severity of CNS inflammation. There are indirect clinical data that suggest thymic function is also important in human CNS autoimmune diseases. Specifically, the association between thymoma and paraneoplastic encephalitis and changes in T cell receptor excision circles in multiple sclerosis implicate thymic tolerance in these diseases. We identify potential associations between CNS autoimmunity susceptibility factors and thymic tolerance. The therapeutic manipulation of thymopoiesis has the potential to open up new treatment modalities, but a better understanding of thymic tolerance in CNS autoimmunity is required before this can be realised.

Recent advances in understanding and managing hypoparathyroidism

Hypoparathyroidism is a rare endocrine disorder which leads to hypocalcemia, hypercalciuria, and hyperphosphatemia. Complications include nephrocalcinosis with renal dysfunction, reduced quality of life, and abnormal skeletal properties. Conventional therapy with calcium and vitamin D analogs addresses hypocalcemia but has important limitations. Parathyroid hormone (PTH) therapy is a fundamental advance, although the effects of PTH on long-term complications require additional testing. Continuous PTH therapy is likely to be particularly advantageous for addressing renal, quality of life, and skeletal complications. Overall, much progress has been made, yet more information is needed to improve our understanding and management of hypoparathyroidism.

Absence of central tolerance in Aire-deficient mice synergizes with immune-checkpoint inhibition to enhance antitumor responses

The endogenous anti-tumor responses are limited in part by the absence of tumor-reactive T cells, an inevitable consequence of thymic central tolerance mechanisms ensuring prevention of autoimmunity. Here we show that tumor rejection induced by immune checkpoint blockade is significantly enhanced in Aire-deficient mice, the epitome of central tolerance breakdown. The observed synergy in tumor rejection extended to different tumor models, was accompanied by increased numbers of activated T cells expressing high levels of Gzma, Gzmb, Perforin, Cxcr3, and increased intratumoural levels of Cxcl9 and Cxcl10 compared to wild-type mice. Consistent with Aire's central role in T cell repertoire selection, single cell TCR sequencing unveiled expansion of several clones with high tumor reactivity. The data suggest that breakdown in central tolerance synergizes with immune checkpoint blockade in enhancing anti-tumor immunity and may serve as a model to unmask novel anti-tumor therapies including anti-tumor TCRs, normally purged during central tolerance.

Hypoparathyroidism

BACKGROUND

Hypoparathyroidism is a rare endocrine disorder characterized by hypocalcemia and low or undetectable levels of parathyroid hormone.

METHODS

This review is an evidence-based summary of hypoparathyroidism in terms of relevant pathophysiological, clinical, and therapeutic concepts.

RESULTS

Many clinical manifestations of hypoparathyroidism are due to the lack of the physiological actions of parathyroid hormone on its 2 major target organs: the skeleton and the kidney. The skeleton is inactive, accruing bone without remodeling it. The kidneys lose the calcium-conserving actions of parathyroid hormone and, thus, excrete a greater fraction of calcium. Biochemical manifestations, besides hypocalcemia and low or undetectable levels of parathyroid hormone, include hyperphosphatemia and low levels of 1,25-dihydroxyvitamin D. Calcifications in the kidney, brain, and other soft tissues are common. Removal of, or damage to, the parathyroid glands at the time of anterior neck surgery is, by far, the most likely etiology. Autoimmune destruction of the parathyroid glands and other genetic causes represent most of the other etiologies. Conventional treatment with calcium and active vitamin D can maintain the serum calcium level but high doses may be required, adding to the risk of long-term soft tissue calcifications. The advent of replacement therapy with recombinant human PTH(1-84) represents a major step in the therapeutics of this disease.

CONCLUSIONS

Advances in our knowledge of hypoparathyroidism have led to greater understanding of the disease itself and our approach to it.

Autoimmune Pituitary Disease: New Concepts With Clinical Implications

Some endocrine disorders, including hypophysitis and isolated adrenocorticotropic hormone (ACTH) deficiency, are caused by an autoimmune response to endocrine organs. Although the pathogenesis of some autoimmune endocrine diseases has been elucidated, it remains obscure for most. Anti-PIT-1 hypophysitis (anti-PIT-1 antibody syndrome) is a newly described pituitary autoimmune disease characterized by acquired and specific growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies. This disorder is associated with a thymoma or neoplasm that ectopically expresses pituitary-specific transcription factor 1 (PIT-1) protein. Circulating anti-PIT-1 antibody is a disease marker, and PIT-1-reactive cytotoxic T cells (CTLs) play a pivotal role in disease development. In addition, isolated ACTH deficiency appears to be caused by autoimmunity to corticotrophs; however, the pathogenesis remains unclear. A recently described case of isolated ACTH deficiency with large cell neuroendocrine carcinoma (LCNEC) showed ectopically expressed proopiomelanocortin (POMC), and circulating anti-POMC antibody and POMC-reactive CTLs were also detected. As CTL infiltrations around corticotrophs were also observed, isolated ACTH deficiency may be associated at least in part with a paraneoplastic syndrome. Although several underlying mechanisms for pituitary autoimmunity have been proposed, these observations highlight the importance of paraneoplastic syndrome as a cause of pituitary autoimmune disease. In this review, we focus on the pathophysiology and connection of anti-PIT-1 hypophysitis and isolated ACTH deficiency and discuss the state-of-art knowledge for understanding pituitary autoimmunity.

Delay in the Diagnosis of APECED: A Case Report and Review of Literature from Iran

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) syndrome is a rare monogenic autosomal recessive disorder caused by biallelic mutations in the AIRE (autoimmune regulator) gene. Patients with APECED present with heterogeneous endocrine and non-endocrine manifestations. In this study, we report an Iranian patient who presented with Addison disease, chronic mucocutaneous candidiasis, alopecia totalis, keratopathy and asplenia treated as an isolated endocrinopathy for 25 years. In the adulthood, the diagnosis of APECED was made by genetic analysis which demonstrated homozygous nonsense p.R257* (c.769C>T) mutation of AIRE. APECED has been shown to be frequent in some ethnicities including Iranian Jews. Therefore, we reviewed 39 Iranian APECED patients published in the literature. We found that most of the Iranian patients were of Jewish ethnic background and presented hypoparathyroidism, adrenal insufficiency, and candidiasis as the main clinical manifestation.

The clinical implications of selective IgA deficiency

Selective IgA deficiency (SIgAD) is the most common primary immunodeficiency but does not always result in clinical disease. This may in part be due to the definition based on serum IgA, while most IgA is secreted at mucosal surfaces, not amenable to measurement. Clinical complications include increased risk of sinopulmonary infections with bacteria and viruses, gastrointestinal infections with a predilection for Giardia lamblia, a myriad of autoimmune diseases including systemic lupus erythematosus, hyper- and hypo-thyroidism, Type 1 diabetes, celiac disease, and rarely, malignancy. SIgAD must be differentiated from IgA deficiency that may be seen with IgG2 or IgG4 deficiency, specific antibody deficiency, or as an early manifestation prior to a diagnosis of common variable immunodeficiency. Secondary IgA deficiency is increasingly recognized and may be due to medications such as anti-epileptics, or antibiotics with disruption of the microbiome which can influence IgA levels, infections or malignancies. Patients with SIgAD should be monitored at regular intervals and educated to be aware of particular complications. There is a rare chance of development of anti-IgA IgE antibodies in patients with complete deficiency, which can result in anaphylaxis if blood products with IgA are administered. Prophylactic antibiotics may be indicated in some cases, and very rarely, supplemental IgG infusions.

Type I interferons in host defence and inflammatory diseases

Type I interferons (IFN) can have dual and opposing roles in immunity, with effects that are beneficial or detrimental to the individual depending on whether IFN pathway activation is transient or sustained. Determinants of IFN production and its functional consequences include the nature of the microbial or nucleic acid stimulus, the type of nucleic acid sensor involved in inducing IFN, the predominant subtype of type I IFN produced and the immune ecology of the tissue at the time of IFN expression. When dysregulated, the type I IFN system drives many autoimmune and non-autoimmune inflammatory diseases, including SLE and the tissue inflammation associated with chronic infection. The type I IFN system may also contribute to outcomes for patients affected by solid cancers or myocardial infarction. Significantly more research is needed to discern the mechanisms of induction and response to type I IFNs across these diseases, and patient endophenotyping may help determine whether the cytokine is acting as 'friend' or 'foe', within a particular patient, and at the time of treatment. This review summarises key concepts and discussions from the second International Summit on Interferons in Inflammatory Diseases, during which expert clinicians and scientists evaluated the evidence for the role of type I IFNs in autoimmune and other inflammatory diseases.

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.

Monogenic polyautoimmunity in primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) consist of a large group of genetic disorders that affect distinct components of the immune system. PID patients are susceptible to infection and non-infectious complications, particularly autoimmunity. A specific group of monogenic PIDs are due to mutations in genes that are critical for the regulation of immunological tolerance and immune responses. This group of monogenic PIDs is at high risk of developing polyautoimmunity (i.e., the presence of more than one autoimmune disease in a single patient) because of their impaired immunity. In this review, we discuss the mechanisms of autoimmunity in PIDs and the characteristics of polyautoimmunity in the following PIDs: IPEX; monogenic IPEX-like syndrome; LRBA deficiency; CTLA4 deficiency; APECED; ALPS; and PKCδ deficiency.