Screening patients with autoimmune endocrine disorders for cytokine autoantibodies reveals monogenic immune deficiencies

Anti-perilipin-1 autoantibodies in autoimmune Addison's disease and related endocrine disorders

Immune-mediated lipodystrophy syndromes are rare autoimmune disorders characterized by complete or partial destruction of adipocytes in the body. Recently, autoantibodies against perilipin-1 (PLIN1-autoAbs) have been linked to lipodystrophy. Since various perilipins are expressed in the adrenal cortex and ovaries, we asked whether PLIN1-autoAbs were present in patients with adrenal dysfunction and other autoimmune endocrinopathies. Using a sensitive radiobinding immune assay we analyzed anti-PLIN1-autoAbs in 521 patients with endocrinopathies including Sjögren's syndrome. We identified 22 (4.2%) PLIN1-autoAbs positive patients, of whom 15% had autoimmune polyendocrine syndrome type 1 (4/27), 4% autoimmune Addison's disease and/or autoimmune polyendocrine syndrome type 2 (11/274), 8% type 1 diabetes patients (4/53), and 2% Sjögren's syndrome patients (1/50). However, none of them had known lipodystrophy. In conclusion, PLIN1-autoAbs are found in subgroups of autoimmune endocrinopathies and indicate autoimmunity against adipose tissue, but their pathogenic role if any, remains to be defined. Investigating their role in disease progression and their potential as therapeutic targets could pave the way for novel interventions in autoimmune endocrine diseases.

Type I interferon autoantibody footprints reveal neutralizing mechanisms and allow inhibitory decoy design

Autoantibodies neutralizing type I interferons (IFN-Is; IFNα or IFNω) exacerbate severe viral disease, but specific treatments are unavailable. With footprint profiling, we delineate two dominant IFN-I faces commonly recognized by neutralizing IFN-I autoantibody-containing plasmas from aged individuals with HIV-1 and from individuals with severe COVID-19. These faces overlap with IFN-I regions independently essential for engaging the IFNAR1/IFNAR2 heterodimer, and neutralizing plasmas efficiently block the interaction of IFN-I with both receptor subunits in vitro. In contrast, non-neutralizing autoantibody-containing plasmas limit the interaction of IFN-I with only one receptor subunit and display relatively low IFN-I-binding avidities, thus likely hindering neutralizing function. Iterative engineering of signaling-inert mutant IFN-Is (simIFN-Is) retaining dominant autoantibody targets created potent decoys that prevent IFN-I neutralization by autoantibody-containing plasmas and that restore IFN-I-mediated antiviral activity. Additionally, microparticle-coupled simIFN-Is were effective at depleting IFN-I autoantibodies from plasmas, leaving antiviral antibodies unaffected. Our study reveals mechanisms of action for IFN-I autoantibodies and demonstrates a proof-of-concept strategy to alleviate pathogenic effects.

Type-Specific Impacts of Protein Defects in Pathogenic NFKB2 Variants: Novel Clinical Findings From 138 Patients

BACKGROUND

The noncanonical NF-κB2 (nuclear factor kappa B subunit 2) pathway is integral in regulating immunologic responses, supervising immune function, development, and homeostasis. NFKB2 encodes the cytoplasmic precursor p100, which undergoes processing of its inhibitory C-terminal half to generate p52. Impeding C-terminal defects are well established to cause primary immunodeficiency disorder. In contrast, the mechanism of truncating N-terminal defects remains obscure.

OBJECTIVE

We characterized clinical phenotypes associated with 3 distinct protein-defect types: (1) early truncations: typically occurring N-terminal relative to the nuclear localization sequence and affecting the Rel homology domain, predicting p100 expression to be halved and subsequent p52 generation by processing to be diminished; (2) central truncations: mainly affecting the ARD and predicting immediate expression of p52-like proteins and a 50% reduction of p100; and (3) C-terminal phosphorylation-/ubiquitination domain defects: causing expression of nonprocessable p100 with retained IκB-like activity and subsequently reducing generation of p52.

METHODS

We performed literature research on PubMed, Clinvar, and Human Gene Mutation Database collecting clinical and immunologic data on NFKB2 patients, focusing on comparing protein-defect-specific impacts.

RESULTS

The highest prevalence of early-onset primary immunodeficiency disorder and antibody deficiency occurred in the CTD-defect group. In addition, endocrinological abnormalities and T-cell-mediated autoimmunity were common and frequently required immunosuppression. An extensive immunologic workup revealed patients with C-terminal defects to have pan-hypogammaglobulinemia and reduced specific antibody responses and markedly impaired B-cell differentiation, but normal to elevated T-cell counts. In contrast, pathogenic NFKB2 variants causing central or early-truncating protein defects were only partially penetrant, with ameliorated symptoms and diminished T-cell-mediated autoimmunity.

CONCLUSIONS

Our work defines a clear genotype-phenotype correlation for NFKB2 mutations.

Aire Mutations and Autoimmune Diseases

Autoimmune diseases were first recognized by Mackay and Macfarlane Burnet in 1962 (Burnet and Mackay 1962). It is defined as the failure of an organism to tolerate its own cells and tissue, resulting in an aberrant immune response by lymphocytes (T-cell-driven disease) and/or antibodies (B-cell-driven disease). Autoimmune diseases can be divided into systemic autoimmune diseases and specific organ- or body-system diseases, including the endocrine, gastro-intestinal, and neurological systems, and it's not uncommon for individuals to experience multiple autoimmune conditions simultaneously. Autoimmune diseases affect ~10% of the population (Conrad et al. 2023), causing chronic suffering, vital organ failure, and premature death at the level of cancer and cardiovascular diseases. The rising incidence of these disorders poses a significant challenge to healthcare systems, underscoring the critical need to elucidate disease mechanisms and translate these into effective diagnostic tests and therapeutics. Current therapeutic strategies are predominantly confined to symptomatic relief through replacement therapy and broad-spectrum anti-inflammatory drugs, often resulting in increased disease burden, diminished life quality, and elevated mortality rates. Most autoimmune diseases are likely a result of a combination of different genetic and environmental factors. However, there are a few exemptions, like the autoimmune polyendocrine syndrome type 1 (APS-1) caused by mutations in the Autoimmune Regulator (AIRE) gene.

Helios-Illuminating the way for lymphocyte self-control

Transcription factor Helios, encoded by the IKZF2 gene, has an important role in regulatory T cells by stabilizing their suppressive phenotype. While Helios is prominently expressed in regulatory T cells, its expression extends beyond to include effector T cells, follicular regulatory T cells, B cells, and innate-like lymphocyte populations. Recent characterizations of patients with inborn error of immunity due to damaging IKZF2 variants coupled with translational research on lymphocytes from healthy individuals, have increased our understanding on Helios' multifaceted role in controlling the human adaptive immune system. A less studied role for Helios beyond the stabilizing of regulatory T cells has emerged in directing effector T cell maturation. In the absence of functional Helios, effector T cells acquire more inflammatory phenotype and are prone to senescence. Loss of Helios expression disrupts the regulation of the germinal centre reaction, often resulting in either hypogammaglobulinemia or B cell autoimmunity. This review summarizes findings from studies in both mice and men offering a comprehensive understanding of the impact of the transcription factor Helios on the adaptive immune system.

A transdiagnostic and diagnostic-specific approach on inflammatory biomarkers in eating disorders: A meta-analysis and systematic review

Eating disorders (EDs) are severe mental illnesses with a multifactorial etiology and a chronic course. Among the biological factors related to pathogenesis and maintenance of EDs, inflammation acquired growing scientific interest. This study aimed to assess the inflammatory profile of EDs, focusing on anorexia nervosa, bulimia nervosa, and including for the first time binge eating disorder. A comprehensive research of existing literature identified 51 eligible studies for meta-analysis, comparing levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), osteoprotegerin (OPG), soluble receptor activator of nuclear factor kappa-B ligand (sRANKL), interleukin-1β (IL-1β), and interleukin-10 (IL-10) between patients with EDs and healthy controls (HCs). The systematic review explored other inflammatory biomarkers of interest, which did not meet the meta-analysis criteria. Results revealed significantly elevated levels of TNF-α, OPG, sRANKL, and IL-1β in patients with EDs compared to HCs. Additionally, the results highlighted the heterogeneity of inflammatory state among patients with EDs, emphasizing the need for further research into the association between inflammatory biomarkers and psychopathological correlates. This approach should transcend categorical diagnoses, enabling more precise subcategorizations of patients. Overall, this study contributed to the understanding of the inflammatory pathways involved in EDs, emphasizing potential implications for diagnosis, staging, and targeted interventions.

A sensitive assay for measuring whole-blood responses to type I IFNs

Human inborn errors of the type I IFN response pathway and auto-Abs neutralizing IFN-α, -β, and/or -ω can underlie severe viral illnesses. We report a simple assay for the detection of both types of condition. We stimulate whole blood from healthy individuals and patients with either inborn errors of type I IFN immunity or auto-Abs against type I IFNs with glycosylated human IFN-α2, -β, or -ω. As controls, we add a monoclonal antibody (mAb) blocking the type I IFN receptors and stimulated blood with IFN-γ (type II IFN). Of the molecules we test, IP-10 (encoded by the interferon-stimulated gene (ISG) CXCL10) is the molecule most strongly induced by type I and type II IFNs in the whole blood of healthy donors in an ELISA-like assay. In patients with inherited IFNAR1, IFNAR2, TYK2, or IRF9 deficiency, IP-10 is induced only by IFN-γ, whereas, in those with auto-Abs neutralizing specific type I IFNs, IP-10 is also induced by the type I IFNs not neutralized by the auto-Abs. The measurement of type I and type II IFN-dependent IP-10 induction therefore constitutes a simple procedure for detecting rare inborn errors of the type I IFN response pathway and more common auto-Abs neutralizing type I IFNs.

Loss of tolerance precedes triggering and lifelong persistence of pathogenic type I interferon autoantibodies

Autoantibodies neutralizing type I interferons (IFN-Is) can underlie infection severity. Here, we trace the development of these autoantibodies at high-resolution using longitudinal samples from 1,876 well-treated individuals living with HIV over a 35-year period. Similar to general populations, ∼1.9% of individuals acquired anti-IFN-I autoantibodies as they aged (median onset ∼63 years). Once detected, anti-IFN-I autoantibodies persisted lifelong, and titers increased over decades. Individuals developed distinct neutralizing and non-neutralizing autoantibody repertoires at discrete times that selectively targeted combinations of IFNα, IFNβ, and IFNω. Emergence of neutralizing anti-IFNα autoantibodies correlated with reduced baseline IFN-stimulated gene levels and was associated with subsequent susceptibility to severe COVID-19 several years later. Retrospective measurements revealed enrichment of pre-existing autoreactivity against other autoantigens in individuals who later developed anti-IFN-I autoantibodies, and there was evidence for prior viral infections or increased IFN at the time of anti-IFN-I autoantibody triggering. These analyses suggest that age-related loss of self-tolerance prior to IFN-I immune-triggering poses a risk of developing lifelong functional IFN-I deficiency.

Clinical, Immunological, and Genetic Features in Patients with NFKB1 and NFKB2 Mutations: a Systematic Review

BACKGROUND

Inborn errors of immunity (IEIs) encompass various diseases with diverse clinical and immunological symptoms. Determining the genotype-phenotype of different variants in IEI entity precisely is challenging, as manifestations can be heterogeneous even in patients with the same mutated gene.

OBJECTIVE

In the present study, we conducted a systematic review of patients recorded with NFKB1 and NFKB2 mutations, two of the most frequent monogenic IEIs.

METHODS

The search for relevant literature was conducted in databases including Web of Science, PubMed, and Scopus. Information encompassing demographic, clinical, immunological, and genetic data was extracted from cases reported with mutations in NFKB1 and NFKB2. The comprehensive features of manifestations in patients were described, and a comparative analysis of primary characteristics was conducted between individuals with NFKB1 loss of function (LOF) and NFKB2 (p52-LOF/IκBδ-gain of function (GOF)) variants.

RESULTS

A total of 397 patients were included in this study, 257 had NFKB1 mutations and 140 had NFKB2 mutations. There were 175 LOF cases in NFKB1 and 122 p52LOF/IκBδGOF cases in NFKB2 pivotal groups with confirmed functional implications. NFKB1LOF and p52LOF/IκBδGOF predominant cases (81.8% and 62.5% respectively) initially presented with a CVID-like phenotype. Patients with NFKB1LOF variants often experienced hematologic autoimmune disorders, whereas p52LOF/IκBδGOF patients were more susceptible to other autoimmune diseases. Viral infections were markedly higher in p52LOF/IκBδGOF cases compared to NFKB1LOF (P-value < 0.001). NFKB2 (p52LOF/IκBδGOF) patients exhibited a greater prevalence of ectodermal dysplasia and pituitary gland involvement than NFKB1LOF patients. Most NFKB1LOF and p52LOF/IκBδGOF cases showed low CD19 + B cells, with p52LOF/IκBδGOF having more cases of this type. Low memory B cells were more common in p52LOF/IκBδGOF patients.

CONCLUSIONS

Patients with NFKB2 mutations, particularly p52LOF/IκBδGOF, are at higher risk of viral infections, pituitary gland involvement, and ectodermal dysplasia compared to patients with NFKB1LOF mutations. Genetic testing is essential to resolve the initial complexity and confusion surrounding clinical and immunological features. Emphasizing the significance of functional assays in determining the probability of correlations between mutations and immunological and clinical characteristics of patients is crucial.

Interferon autoantibodies as signals of a sick thymus

Type I interferons (IFN-I) are key immune messenger molecules that play an important role in viral defense. They act as a bridge between microbe sensing, immune function magnitude, and adaptive immunity to fight infections, and they must therefore be tightly regulated. It has become increasingly evident that thymic irregularities and mutations in immune genes affecting thymic tolerance can lead to the production of IFN-I autoantibodies (autoAbs). Whether these biomarkers affect the immune system or tissue integrity of the host is still controversial, but new data show that IFN-I autoAbs may increase susceptibility to severe disease caused by certain viruses, including SARS-CoV-2, herpes zoster, and varicella pneumonia. In this article, we will elaborate on disorders that have been identified with IFN-I autoAbs, discuss models of how tolerance to IFN-Is is lost, and explain the consequences for the host.

A novel missense mutation in the AIRE gene underlying autoimmune polyglandular syndrome type 1

The immune regulator gene AIRE plays an essential role in the establishment of immune tolerance and the prevention of autoimmunity. This transcription factor plays a critical role in promoting self-tolerance in the thymus by regulating the expression of a large number of self-antigens that share the common feature of being tissue-restricted in their expression pattern in the periphery. Dysfunction of AIRE in humans causes a rare disease, autoimmune polyglandular syndrome type 1 (APS1), characterized by an autoimmune response against peripheral tissues, particularly endocrine tissues. Although a few dominant mutations have been described, the inactivation of AIRE is usually caused by recessive mutations. Recent data suggests that alterations in AIRE function contribute not only to APS1 but also to more common forms of autoimmune disease. Here, we present a previously unreported missense mutation (NM_000383.2:c.260 T > C) in exon 2 of the AIRE gene, predicted to cause the substitution (p.(Leu87Pro)) in the CARD domain of the AIRE protein. When inherited in conjunction with another dysfunctional AIRE allele, this mutation was associated with immune dysregulation in a pediatric patient. The presence of hypergammaglobulinemia, malabsorption syndrome, ectodermal dysplasia, mucocutaneous candidiasis, vitiligo, and hypothyroidism as well as the presence of multiple autoantibodies allowed us to confirm an APS1 diagnosis.

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.

Addison's Disease: Diagnosis and Management Strategies

We aim to overview Addison's disease (AD) with regard to current diagnosis and management. This is a narrative review of full-length articles published in English between January 2022 and December 2022 (including online ahead of print versions) in PubMed-indexed journals. We included original studies in living humans regardless of the level of statistical significance starting from the key search terms "Addison's disease" or "primary adrenal insufficiency" in title or abstract. We excluded articles with secondary adrenal insufficiency. Briefly, 199 and 355 papers, respectively were identified; we manually checked each of them, excluded the duplicates, and then selected 129 based on their clinical relevance in order to address our 1-year analysis. We organized the data in different subsections covering all published aspects on the subject of AD. To our knowledge, this is the largest AD retrospective from 2022 on published data. A massive role of genetic diagnosis especially in pediatric cases is highlighted; the importance of both pediatric and adult awareness remains since unusual presentations continue to be described. COVID-19 infection is a strong player amid this third year of pandemic although we still not do have large cohorts in this particular matter as seen, for instance, in thyroid anomalies. In our opinion, the most important topic for research is immune checkpoint inhibitors, which cause a large panel of endocrine side effects, AD being one of them.

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.