Distinct Functions of Autoantibodies Against Interferon in Systemic Lupus Erythematosus: A Comprehensive Analysis of Anticytokine Autoantibodies in Common Rheumatic Diseases

Autoantibodies to type I interferons in patients with systemic mastocytosis

Background

Autoantibodies to type I interferons have been identified in association with a variety of inflammatory and autoimmune diseases. Type I interferons have demonstrated inhibitory effects on mast cell proliferation and degranulation. Systemic mastocytosis (SM) is a disease characterized by increased mast cell burden and mediator release. Whether autoantibodies to type I interferon are present in the sera of patients with SM, and if so, whether they correlate with characteristics of disease, is unknown.

Objective

The purpose of this study was to determine whether autoantibodies to type I interferons are observed in the sera of patients with SM, and if so, whether they correlate with biomarkers of disease severity.

Methods

We analyzed sera from 89 patients with SM for concentrations of autoantibodies to type I interferon by using a multiplex particle-based assay and signal neutralization capacity by using a STAT1 activity assay and then compared these measurements with those in a database of information on 1284 healthy controls.

Results

Our cohort was predominantly female (57.3%), with a median age of 56 years. Of the cohort members, 13 produced autoantibodies to IFN-β, 3 to IFN-ω, and 0 to IFN-α. None of the 13 sera demonstrated signal neutralization. Neither autoantibody concentration nor signaling inhibition measurements correlated with tryptase concentrations or D816V allele burden.

Conclusion

Although a small subpopulation of patients with SM have autoantibodies to type I interferons, there was no correlation between autoantibody production and signaling inhibition. These data are consistent with the conclusion that autoantibodies to type I interferon do not play a significant role in the pathogenesis or severity of SM.

Standing on Shoulders: Interferon Research From Viral Interference to Lupus Pathogenesis and Treatment

The discovery of interferon in the 1950s represents much more than the identification of the first cytokine and the key mediator of antiviral host defense. Defining the molecular nature and complexity of the type I interferon family, as well as its inducers and molecular mechanisms of action, was the work of investigators working at the highest level and producing insights of great consequence. Current knowledge of receptor-ligand interactions, cell signaling, and transcriptional regulation derives from studies of type I interferon. It is on the shoulders of the giants who produced that knowledge that others stand and have revealed critical mechanisms of the pathogenesis of systemic lupus erythematosus and other autoimmune diseases. The design of novel therapeutics is informed by the advances in investigation of type I interferon, with the potential for important impact on patient management.

Cellular pathways and molecular events that shape autoantibody production in COVID-19

A hallmark of COVID-19 is the variety of complications that follow SARS-CoV-2 infection in some patients, and that target multiple organs and tissues. Also remarkable are the associations with several auto-inflammatory disorders and the presence of autoantibodies directed to a vast array of antigens. The processes underlying autoantibody production in COVID-19 have not been completed deciphered. Here, we review mechanisms involved in autoantibody production in COVID-19, multisystem inflammatory syndrome in children, and post-acute sequelae of COVID19. We critically discuss how genomic integrity, loss of B cell tolerance to self, superantigen effects of the virus, and extrafollicular B cell activation could underly autoantibody proaction in COVID-19. We also offer models that may account for the pathogenic roles of autoantibodies in the promotion of inflammatory cascades, thromboembolic phenomena, and endothelial and vascular deregulations.

Association of the Reduced Levels of Monocyte Chemoattractant Protein-1 with Herpes Zoster in Rheumatoid Arthritis Patients Treated with Janus Kinase Inhibitors in a Single-Center Cohort

Anti-interferon (IFN)-γ autoantibodies are linked to varicella zoster virus (VZV) infection. Given the elevated risks of herpes zoster (HZ) in rheumatoid arthritis (RA) patients treated with Janus kinase inhibitors (JAKis), we aimed to examine the relationship between anti-IFN-γ autoantibodies with HZ development in JAKi-treated patients. Serum titers of anti-IFN-γ autoantibodies, plasma levels of IFN-γ, monocyte chemoattractant protein-1 (MCP-1), and IFN-γ-inducible protein-10 (IP-10) were measured by ELISA. Among the 66 enrolled RA patients, 24 developed new-onset HZ. Significantly lower MCP-1 levels were observed in patients with HZ compared to those without (median, 98.21 pg/mL, interquartile range (IQR) 77.63-150.30 pg/mL versus 142.3 pg/mL, IQR 106.7-175.6 pg/mL, p < 0.05). There was no significant difference in anti-IFN-γ titers, IFN-γ levels, or IP-10 levels between patients with and without HZ. Three of 24 patients with HZ had severe HZ with multi-dermatomal involvement. Anti-IFN-γ titers were significantly higher in patients with severe HZ than in those with non-severe HZ (median 24.8 ng/mL, IQR 21.0-38.2 ng/mL versus 10.5 ng/mL, IQR 9.9-15.0 ng/mL, p < 0.005). Our results suggest an association between reduced MCP-1 levels and HZ development in JAKi-treated RA patients. High-titer anti-IFN-γ autoantibodies may be related to severe HZ in these patients.

Clinical Significance of Uncommon, Non-Clinical, and Novel Autoantibodies

Autoantibodies are a common mark of autoimmune reaction and their identification in the patients' serum, cerebrospinal fluid, or tissues is generally believed to represent diagnostic or prognostic biomarkers of autoimmune diseases or autoinflammatory conditions. Traditionally, autoantibody testing is an important part of the clinical examination of suspected patients, and in the absence of reliable T cell tests, characterization of autoantibody responses might be suitable in finding causes of specific autoimmune responses, their strength, and sometimes commencement of autoimmune disease. Autoantibodies are also useful for prognostic stratification in clinically diverse groups of patients if checked repeatedly. Antibody discoveries are continuing, with important consequences for verifying autoimmune mechanisms, diagnostic feasibility, and clinical management. Adding newly identified autoantibody-autoantigen pairs to common clinical laboratory panels should help upgrade and harmonize the identification of systemic autoimmune rheumatic disorders and other autoimmune conditions. Herein, we aim to summarize our current knowledge of uncommon and novel autoantibodies in the context of discussing their validation, diagnostic practicability, and clinical relevance. The regular updates within the field are important and well justified.

Anti-Interleukin-23 Autoantibodies in Adult-Onset Immunodeficiency

BACKGROUND

Autoantibodies against interleukin-12 (anti-interleukin-12) are often identified in patients with thymoma, but opportunistic infections develop in only some of these patients. Interleukin-12 (with subunits p40 and p35) shares a common subunit with interleukin-23 (subunits p40 and p19). In a patient with disseminated Burkholderia gladioli infection, the identification of both anti-interleukin-23 and anti-interleukin-12 prompted further investigation.

METHODS

Among the patients (most of whom had thymoma) who were known to have anti-interleukin-12, we screened for autoantibodies against interleukin-23 (anti-interleukin-23). To validate the potential role of anti-interleukin-23 with respect to opportunistic infection, we tested a second cohort of patients with thymoma as well as patients without either thymoma or known anti-interleukin-12 who had unusual infections.

RESULTS

Among 30 patients with anti-interleukin-12 who had severe mycobacterial, bacterial, or fungal infections, 15 (50%) also had autoantibodies that neutralized interleukin-23. The potency of such neutralization was correlated with the severity of these infections. The neutralizing activity of anti-interleukin-12 alone was not associated with infection. In the validation cohort of 91 patients with thymoma, the presence of anti-interleukin-23 was associated with infection status in 74 patients (81%). Overall, neutralizing anti-interleukin-23 was detected in 30 of 116 patients (26%) with thymoma and in 30 of 36 patients (83%) with disseminated, cerebral, or pulmonary infections. Anti-interleukin-23 was present in 6 of 32 patients (19%) with severe intracellular infections and in 2 of 16 patients (12%) with unusual intracranial infections, including Cladophialophora bantiana and Mycobacterium avium complex.

CONCLUSIONS

Among patients with a variety of mycobacterial, bacterial, or fungal infections, the presence of neutralizing anti-interleukin-23 was associated with severe, persistent opportunistic infections. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Neutralizing IFN-γ autoantibodies are rare and pathogenic in HLA-DRB1*15:02 or 16:02 individuals

BACKGROUNDWeakly virulent environmental mycobacteria (EM) can cause severe disease in HLA-DRB1*15:02 or 16:02 adults harboring neutralizing anti-IFN-γ autoantibodies (nAIGAs). The overall prevalence of nAIGAs in the general population is unknown, as are the penetrance of nAIGAs in HLA-DRB1*15:02 or 16:02 individuals and the proportion of patients with unexplained, adult-onset EM infections carrying nAIGAs.METHODSThis study analyzed the detection and neutralization of anti-IFN-γ autoantibodies (auto-Abs) from 8,430 healthy individuals of the general population, 257 HLA-DRB1*15:02 or 16:02 carriers, 1,063 patients with autoimmune disease, and 497 patients with unexplained severe disease due to EM.RESULTSWe found that anti-IFN-γ auto-Abs detected in 4,148 of 8,430 healthy individuals (49.2%) from the general population of an unknown HLA-DRB1 genotype were not neutralizing. Moreover, we did not find nAIGAs in 257 individuals carrying HLA-DRB1* 15:02 or 16:02. Additionally, nAIGAs were absent in 1,063 patients with an autoimmune disease. Finally, 7 of 497 patients (1.4%) with unexplained severe disease due to EM harbored nAIGAs.CONCLUSIONThese findings suggest that nAIGAs are isolated and that their penetrance in HLA-DRB1*15:02 or 16:02 individuals is low, implying that they may be triggered by rare germline or somatic variants. In contrast, the risk of mycobacterial disease in patients with nAIGAs is high, confirming that these nAIGAs are the cause of EM disease.FUNDINGThe Laboratory of Human Genetics of Infectious Diseases is supported by the Howard Hughes Medical Institute, the Rockefeller University, the St. Giles Foundation, the National Institutes of Health (NIH) (R01AI095983 and U19AIN1625568), the National Center for Advancing Translational Sciences (NCATS), the NIH Clinical and Translational Science Award (CTSA) program (UL1 TR001866), the French National Research Agency (ANR) under the "Investments for the Future" program (ANR-10-IAHU-01), the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (ANR-10-LABX-62-IBEID), ANR-GENMSMD (ANR-16-CE17-0005-01), ANR-MAFMACRO (ANR-22-CE92-0008), ANRSECTZ170784, the French Foundation for Medical Research (FRM) (EQU201903007798), the ANRS-COV05, ANR GENVIR (ANR-20-CE93-003), and ANR AI2D (ANR-22-CE15-0046) projects, the ANR-RHU program (ANR-21-RHUS-08-COVIFERON), the European Union's Horizon 2020 research and innovation program under grant agreement no. 824110 (EASI-genomics), the Square Foundation, Grandir - Fonds de solidarité pour l'enfance, the Fondation du Souffle, the SCOR Corporate Foundation for Science, the Battersea & Bowery Advisory Group, William E. Ford, General Atlantic's Chairman and Chief Executive Officer, Gabriel Caillaux, General Atlantic's Co-President, Managing Director, and Head of business in EMEA, and the General Atlantic Foundation, Institut National de la Santé et de la Recherche Médicale (INSERM) and of Paris Cité University. JR was supported by the INSERM PhD program for doctors of pharmacy (poste d'accueil INSERM). JR and TLV were supported by the Bettencourt-Schueller Foundation and the MD-PhD program of the Imagine Institute. MO was supported by the David Rockefeller Graduate Program, the Funai Foundation for Information Technology (FFIT), the Honjo International Scholarship Foundation (HISF), and the New York Hideyo Noguchi Memorial Society (HNMS).

Anti-cytokine autoantibodies: mechanistic insights and disease associations

Anti-cytokine autoantibodies (ACAAs) are increasingly recognized as modulating disease severity in infection, inflammation and autoimmunity. By reducing or augmenting cytokine signalling pathways or by altering the half-life of cytokines in the circulation, ACAAs can be either pathogenic or disease ameliorating. The origins of ACAAs remain unclear. Here, we focus on the most common ACAAs in the context of disease groups with similar characteristics. We review the emerging genetic and environmental factors that are thought to drive their production. We also describe how the profiling of ACAAs should be considered for the early diagnosis, active monitoring, treatment or sub-phenotyping of diseases. Finally, we discuss how understanding the biology of naturally occurring ACAAs can guide therapeutic strategies.

Functional genomics in inborn errors of immunity

Inborn errors of immunity (IEI) comprise a diverse spectrum of 485 disorders as recognized by the International Union of Immunological Societies Committee on Inborn Error of Immunity in 2022. While IEI are monogenic by definition, they illuminate various pathways involved in the pathogenesis of polygenic immune dysregulation as in autoimmune or autoinflammatory syndromes, or in more common infectious diseases that may not have a significant genetic basis. Rapid improvement in genomic technologies has been the main driver of the accelerated rate of discovery of IEI and has led to the development of innovative treatment strategies. In this review, we will explore various facets of IEI, delving into the distinctions between PIDD and PIRD. We will examine how Mendelian inheritance patterns contribute to these disorders and discuss advancements in functional genomics that aid in characterizing new IEI. Additionally, we will explore how emerging genomic tools help to characterize new IEI as well as how they are paving the way for innovative treatment approaches for managing and potentially curing these complex immune conditions.

Human autoantibodies neutralizing type I IFNs: From 1981 to 2023

Human autoantibodies (auto-Abs) neutralizing type I IFNs were first discovered in a woman with disseminated shingles and were described by Ion Gresser from 1981 to 1984. They have since been found in patients with diverse conditions and are even used as a diagnostic criterion in patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1). However, their apparent lack of association with viral diseases, including shingles, led to wide acceptance of the conclusion that they had no pathological consequences. This perception began to change in 2020, when they were found to underlie about 15% of cases of critical COVID-19 pneumonia. They have since been shown to underlie other severe viral diseases, including 5%, 20%, and 40% of cases of critical influenza pneumonia, critical MERS pneumonia, and West Nile virus encephalitis, respectively. They also seem to be associated with shingles in various settings. These auto-Abs are present in all age groups of the general population, but their frequency increases with age to reach at least 5% in the elderly. We estimate that at least 100 million people worldwide carry auto-Abs neutralizing type I IFNs. Here, we briefly review the history of the study of these auto-Abs, focusing particularly on their known causes and consequences.

The impact of the COVID-19 pandemic on SLE

Little is known about the association between coronavirus disease 2019 (COVID-19) and autoimmune diseases, especially in the case of systemic lupus erythematosus (SLE). SLE patients met with many questions during the pandemic in COVID-19, such as how to minimize risk of infection, the complex pathological features and cytokine profiles, diagnosis and treatment, rational choice of drugs and vaccine, good nursing, psychological supervision, and so on. In this study, we review and discuss the multifaceted effects of the COVID-19 pandemic on patients living with SLE using the available literature. Cross-talk in implicated inflammatory pathways/mechanisms exists between SLE and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and SARS-CoV-2 displays similar clinical characteristics and immuno-inflammatory responses to SLE. Current epidemiological data inadequately assess the risk and severity of COVID-19 infection in patients with SLE. More evidence has shown that hydroxychloroquine and chloroquine cannot prevent COVID-19. During the pandemic, patients with SLE had a higher rate of hospitalization. Vaccination helps to reduce the risk of infection. Several therapies for patients with SLE infected with COVID-19 are discussed. The cases in the study can provide meaningful information for clinical diagnosis and management. Our main aim is to help preventing infection and highlight treatment options for patients with SLE infected with COVID-19.

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.

IL-1RA autoantibodies: insights into mechanisms and associated diseases

The association of neutralizing autoantibodies targeting interleukin-1 receptor antagonist (IL-1RA) with multisystem inflammatory syndrome, IgG4-related disease, and vaccine-related myocarditis is increasingly recognized. The detection of IL-1RA autoantibodies can be notably affected by the techniques and methods employed. Two categories of assays are available: solid-phase immunoassays, which detect binding of IL-1RA autoantibodies, and functional IL-1 signaling reporter cell assays, which offer greater specificity by determining whether circulating autoantibodies can impede interleukin (IL)-1β signal transduction pathways. It is as yet unclear why only a minority of individuals produce pathogenic anti-IL-1RA autoantibodies in response to coronavirus disease 2019 (COVID19) or vaccination. This review article discusses our current knowledge of the process of IL-1RA autoantibody generation, the underlying pathogenesis, detection, and potential treatment strategies for associated diseases.

Higher COVID-19 pneumonia risk associated with anti-IFN-α than with anti-IFN-ω auto-Abs in children

We found that 19 (10.4%) of 183 unvaccinated children hospitalized for COVID-19 pneumonia had autoantibodies (auto-Abs) neutralizing type I IFNs (IFN-α2 in 10 patients: IFN-α2 only in three, IFN-α2 plus IFN-ω in five, and IFN-α2, IFN-ω plus IFN-β in two; IFN-ω only in nine patients). Seven children (3.8%) had Abs neutralizing at least 10 ng/ml of one IFN, whereas the other 12 (6.6%) had Abs neutralizing only 100 pg/ml. The auto-Abs neutralized both unglycosylated and glycosylated IFNs. We also detected auto-Abs neutralizing 100 pg/ml IFN-α2 in 4 of 2,267 uninfected children (0.2%) and auto-Abs neutralizing IFN-ω in 45 children (2%). The odds ratios (ORs) for life-threatening COVID-19 pneumonia were, therefore, higher for auto-Abs neutralizing IFN-α2 only (OR [95% CI] = 67.6 [5.7-9,196.6]) than for auto-Abs neutralizing IFN-ω only (OR [95% CI] = 2.6 [1.2-5.3]). ORs were also higher for auto-Abs neutralizing high concentrations (OR [95% CI] = 12.9 [4.6-35.9]) than for those neutralizing low concentrations (OR [95% CI] = 5.5 [3.1-9.6]) of IFN-ω and/or IFN-α2.

PD-1/PD-L1 governed cross-talk of exhausted CD8+ T and memory B cells in systemic lupus erythematosus

BACKGROUND

Indeterminate readout of the quantitative interferon-γ release test (QFT) for Mycobacterium tuberculosis screening is a specific laboratory finding for systemic lupus erythematosus (SLE), which may be due to T-cell exhaustion and abnormal programmed death receptor 1 (PD-1)/programmed death-ligand 1 (PD-L1) signalling.

METHODS

We enrolled 104 patients with SLE and 225 with other rheumatic musculoskeletal diseases (RMDs) who presented to the outpatient clinic between 2020 and 2023. Twenty healthy donors served as the controls. The QFT was performed in all participants, and those with indeterminate results were compared among the groups. Immunophenotyping and functional assays were performed using blood mononuclear cells. Interferon (IFN)-γ was detected in vitro and ex vivo in patients with SLE with indeterminate or negative QFT results, before or after rituximab therapy.

RESULTS

104 patients with SLE had a significantly higher rate of indeterminate QFT results was significantly higher (17.31%) than that of 225 patients with RMD (3.56%). Patients with SLE with indeterminate QFT had more active disease (SLEDAI-2K, mean 10.94 vs 4.02, p<0.0001), including a higher incidence of active nephritis (55.56% vs 29.07%). Indeterminate QFT in SLE is mainly caused by an insufficient IFN-γ response in CD8+T cells with exhausted immunophenotypes. The abnormal interaction between exhausted PD-1 high CD8+ T cells and activated PD-L1 low memory B cells in SLE can be reversed with a PD-1 agonist or increased PD-L1 expression. Rituximab treatment indirectly reversed this IFN-γ response.

CONCLUSION

The PD-1/PD-L1 signalling pathway, which governs the crosstalk between exhausted CD8+ T cells and activated memory B cells, is a mechanistic explanation for insufficient interferon-γ response in patients with SLE.

Neutralizing anti-IFN-γ IgG was increased in patients with systemic lupus erythematosus and associated with susceptibility to infection

OBJECTIVES

Systemic lupus erythematosus (SLE) is a complicated autoimmune disease, in which infection is a leading cause of death. Some SLE patients clinically presented with recurrent and refractory infections, which manifested as adult-onset immunodeficiency syndrome due to the production of anti-interferon-γ (anti-IFN-γ) autoantibodies. This study aimed to investigate the role of anti-IFN-γ autoantibodies concerning severe infections in SLE patients.

METHODS

We detected serum levels of anti-IFN-γ IgG/IgM isotypes in SLE patients with severe infections (n = 55), SLE patients without severe infections (n = 120), rheumatoid arthritis (n = 24), ankylosing spondylitis (n = 24), and healthy controls (n = 60). The relationship between anti-IFN-γ autoantibodies and clinical characteristics and laboratory parameters were analyzed. We further evaluated the neutralizing ability of anti-IFN-γ IgG.

RESULTS

The level of anti-IFN-γ IgG was significantly elevated in SLE patients with severe infections compared with the other groups (all p < 0.01), and the positive rates of anti-IFN-γ IgG in SLE patients with and without severe infections were 29.1% and 10.8%, respectively. Further analysis indicated that the levels of anti-IFN-γ IgG were positively associated with the SLEDAI score (r = 0.6420, p < 0.001), and it could predict the susceptibility to severe infections in SLE patients. Moreover, the inhibition and function assay showed that purified IgG from anti-IFN-γ IgG-positive SLE patients could neutralize IFN-γ, and further impair IFN-γ-induced STAT1 phosphorylation.

CONCLUSIONS

The neutralizing anti-IFN-γ IgG might increase the susceptibility to infection in SLE patients, which has important implications for the treatment. Key Points • The role of anti-IFN-γ autoantibodies concerning severe infections in SLE patients remains unknown. • The results of this study reveals that anti-IFN-γ IgG levels were significantly elevated in SLE patients with severe infections. • This study suggests that neutralizing anti-IFN-γ IgG might increase the susceptibility to infection in SLE patients.

Tsokos G. Infections in Patients with Systemic Lupus Erythematosus: The Contribution of Primary Immune Defects Versus Treatment-Induced Immunosuppression

Patients with systemic lupus erythematosus experience high rates of infections. The use of immunosuppressive drugs to treat the disease, along with the fact that both the innate and adaptive branches of the immune system are compromised, account for the development of infections. In this communication, we briefly discuss the aberrant function of the immune system in patients with systemic lupus erythematosus and review the occurrence of infections that have been reported in clinical trials conducted to develop new therapeutics. Understanding the immune dysfunction in patients with systemic lupus erythematosus and the appearance of infections while trying to control the disease using immunosuppressive or immunomodulatory drugs should help limit infections and mitigate the associated morbidity and mortality.

Lupus Nephritis Risk Factors and Biomarkers: An Update

Lupus nephritis (LN) represents the most severe organ manifestation of systemic lupus erythematosus (SLE) in terms of morbidity and mortality. To reduce these risks, tremendous efforts have been made in the last decade to characterize the different steps of the disease and to develop biomarkers in order to better (i) unravel the pre-SLE stage (e.g., anti-nuclear antibodies and interferon signature); (ii) more timely initiation of therapy by improving early and accurate LN diagnosis (e.g., pathologic classification was revised); (iii) monitor disease activity and therapeutic response (e.g., recommendation to re-biopsy, new urinary biomarkers); (iv) prevent disease flares (e.g., serologic and urinary biomarkers); (v) mitigate the deterioration in the renal function; and (vi) reduce side effects with new therapeutic guidelines and novel therapies. However, progress is poor in terms of improvement with early death attributed to active SLE or infections, while later deaths are related to the chronicity of the disease and the use of toxic therapies. Consequently, an individualized treat-to-target strategy is mandatory, and for that, there is an unmet need to develop a set of accurate biomarkers to be used as the standard of care and adapted to each stage of the disease.

Inhibition of JAK-STAT pathway corrects salivary gland inflammation and interferon driven immune activation in Sjögren's Disease

Objectives

Inflammatory cytokines that signal through the JAK- STAT pathway, especially interferons (IFNs), are implicated in Sjögren's Disease (SjD). Although inhibition of JAKs is effective in other autoimmune diseases, a systematic investigation of IFN-JAK-STAT signaling and effect of JAK inhibitor (JAKi) therapy in SjD-affected human tissues has not been reported.

Methods

Human minor salivary glands (MSGs) and peripheral blood mononuclear cells (PBMCs) were investigated using bulk or single cell (sc) RNA sequencing (RNAseq), immunofluorescence microscopy (IF), and flow cytometry. Ex vivo culture assays on PBMCs and primary salivary gland epithelial cell (pSGEC) lines were performed to model changes in target tissues before and after JAKi.

Results

RNAseq and IF showed activated JAK-STAT pathway in SjD MSGs. Elevated IFN-stimulated gene (ISGs) expression associated with clinical variables (e.g., focus scores, anti-SSA positivity). scRNAseq of MSGs exhibited cell-type specific upregulation of JAK-STAT and ISGs; PBMCs showed similar trends, including markedly upregulated ISGs in monocytes. Ex vivo studies showed elevated basal pSTAT levels in SjD MSGs and PBMCs that were corrected with JAKi. SjD-derived pSGECs exhibited higher basal ISG expressions and exaggerated responses to IFNβ, which were normalized by JAKi without cytotoxicity.

Conclusions

SjD patients' tissues exhibit increased expression of ISGs and activation of the JAK-STAT pathway in a cell type-dependent manner. JAKi normalizes this aberrant signaling at the tissue level and in PBMCs, suggesting a putative viable therapy for SjD, targeting both glandular and extraglandular symptoms. Predicated on these data, a Phase Ib/IIa randomized controlled trial to treat SjD with tofacitinib was initiated.

Heterogeneity and functions of the 13 IFN-α subtypes - lucky for some?

Type I IFNs are critical for host responses to viral infection and are also implicated in the pathogenesis of multiple autoimmune diseases. Multiple subtypes exist within the type I IFN family, in particular 13 distinct IFN-α genes, which signal through the same heterodimer receptor that is ubiquitously expressed by mammalian cells. Both evolutionary genetic studies and functional antiviral assays strongly suggest differential functions and activity between the 13 IFN-α subtypes, yet we still lack a clear understanding of these different roles. This review summarizes the evidence from studies describing differential functions of IFN-α subtypes and highlights potential reasons for discrepancies between the reports. We examine both acute and chronic viral infection, as well as autoimmunity, and integrate a more recent awareness of the importance of anti-IFN-α autoantibodies in shaping the type I IFN responses in these different conditions.

Anticytokine Autoantibodies and Fungal Infections

Anticytokine autoantibodies (ACAAs) can cause adult onset immunodeficiencies which mimic primary immunodeficiencies and can present as refractory and severe fungal infections. This paper provides an overview of the role of innate immunity, including key cytokines, in fungal infections and then describes four clinical scenarios where ACAAs are associated with severe presentations of a fungal infection: (1) Talaromyces marneffei infection and anti-interferon-γ, (2) histoplasmosis and anti-interferon-γ, (3) Cryptococcus gattii infection and anti-GM-CSF, and (4) mucocutaneous candidiasis and anti-IL-17A/F (IL-22). Testing for ACAAs and potential therapeutic options are discussed.

Autoantibodies to Interferons in Infectious Diseases

Anti-cytokine autoantibodies and, in particular, anti-type I interferons are increasingly described in association with immunodeficient, autoimmune, and immune-dysregulated conditions. Their presence in otherwise healthy individuals may result in a phenotype characterized by a predisposition to infections with several agents. For instance, anti-type I interferon autoantibodies are implicated in Coronavirus Disease 19 (COVID-19) pathogenesis and found preferentially in patients with critical disease. However, autoantibodies were also described in the serum of patients with viral, bacterial, and fungal infections not associated with COVID-19. In this review, we provide an overview of anti-cytokine autoantibodies identified to date and their clinical associations; we also discuss whether they can act as enemies or friends, i.e., are capable of acting in a beneficial or harmful way, and if they may be linked to gender or immunosenescence. Understanding the mechanisms underlying the production of autoantibodies could improve the approach to treating some infections, focusing not only on pathogens, but also on the possibility of a low degree of autoimmunity in patients.

Interferon and autoantigens: intersection in autoimmunity

Interferon (IFN) is a key component of the innate immune response. For reasons that remain incompletely understood, the IFN system is upregulated in several rheumatic diseases, particularly those that feature autoantibody production, such as SLE, Sjögren's syndrome, myositis and systemic sclerosis. Interestingly, many of the autoantigens targeted in these diseases are components of the IFN system, representing IFN-stimulated genes (ISGs), pattern recognition receptors (PRRs), and modulators of the IFN response. In this review, we describe features of these IFN-linked proteins that may underlie their status as autoantigens. Note is also made of anti-IFN autoantibodies that have been described in immunodeficiency states.

Type I interferon autoantibodies in hospitalized patients with Middle East respiratory syndrome and association with outcomes and treatment effect of interferon beta‐1b in MIRACLE clinical trial

Background

Type I interferons (IFNs) are essential antiviral cytokines induced upon respiratory exposure to coronaviruses. Defects in type I IFN signaling can result in severe disease upon exposure to respiratory viral infection and are associated with worse clinical outcomes. Neutralizing autoantibodies (auto‐Abs) to type I IFNs were reported as a risk factor for life‐threatening COVID‐19, but their presence has not been evaluated in patients with severe Middle East respiratory syndrome (MERS).

Methods

We evaluated the prevalence of type I IFN auto‐Abs in a cohort of hospitalized patients with MERS who were enrolled in a placebo‐controlled clinical trial for treatment with IFN‐β1b and lopinavir‐ritonavir (MIRACLE trial). Samples were tested for type I IFN auto‐Abs using a multiplex particle‐based assay.

Results

Among the 62 enrolled patients, 15 (24.2%) were positive for immunoglobulin G auto‐Abs for at least one subtype of type I IFNs. Auto‐Abs positive patients were not different from auto‐Abs negative patients in age, sex, or comorbidities. However, the majority (93.3%) of patients who were auto‐Abs positive were critically ill and admitted to the ICU at the time of enrollment compared to 66% in the auto‐Abs negative patients. The effect of treatment with IFN‐β1b and lopinavir‐ritonavir did not significantly differ between the two groups.

Conclusion

This study demonstrates the presence of type I IFN auto‐Abs in hospitalized patients with MERS.

Molecular endotypes of type 1 and type 2 SLE

OBJECTIVE

To character the molecular landscape of patients with type 1 and type 2 SLE by analysing gene expression profiles from peripheral blood.

METHODS

Full transcriptomic RNA sequencing was carried out on whole blood samples from 18 subjects with SLE selected by the presence of manifestations typical of type 1 and type 2 SLE. The top 5000 row variance genes were analysed by Multiscale Embedded Gene Co-expression Network Analysis to generate gene co-expression modules that were functionally annotated and correlated with various demographic traits, clinical features and laboratory measures.

RESULTS

Expression of specific gene co-expression modules correlated with individual features of type 1 and type 2 SLE and also effectively segregated samples from patients with type 1 SLE from those with type 2 SLE. Unique type 1 SLE enrichment included interferon, monocytes, T cells, cell cycle and neurotransmitter pathways, whereas unique type 2 SLE enrichment included B cells and metabolic and neuromuscular pathways. Gene co-expression modules of patients with type 2 SLE were identified in subsets of previously reported patients with inactive SLE and idiopathic fibromyalgia (FM) and also identified subsets of patients with active SLE with a greater frequency of severe fatigue.

CONCLUSION

Gene co-expression analysis successfully identified unique transcriptional patterns that segregate type 1 SLE from type 2 SLE and further identified type 2 molecular features in patients with inactive SLE or FM and with active SLE with severe fatigue.

Transient autoantibodies to danger signals

The Danger Model predicts that there are some molecules that no immune system can ever be fully tolerant of, namely proteins that are only transiently expressed during times of stress, infection, or injury. Among these are the danger/alarm signals themselves. Accordingly, a fleeting autoantibody response to danger signals is expected during times when they are released. Depending on context, these autoantibodies may serve beneficial "housekeeping" functions by removing surplus danger signals from the circulation or, conversely, create an immunodeficiency. Here, we will focus on the Type 1 Interferons as examples of foreseeable targets for a transient autoantibody response, but the principles outlined should hold for other danger-associated molecules as well.

Inactive disease in patients with lupus is linked to autoantibodies to type I interferons that normalize blood IFNα and B cell subsets

Systemic lupus erythematosus (SLE) is characterized by increased expression of type I interferon (IFN)-regulated genes in 50%-75% of patients. We report that out of 501 patients with SLE analyzed, 73 (14%) present autoantibodies against IFNα (anti-IFN-Abs). The presence of neutralizing-anti-IFN-Abs in 4.2% of patients inversely correlates with low circulating IFNα protein levels, inhibition of IFN-I downstream gene signatures, and inactive global disease score. Hallmarks of SLE pathogenesis, including increased immature, double-negative plasmablast B cell populations and reduction in regulatory B cell (Breg) frequencies, were normalized in patients with neutralizing anti-IFN-Abs compared with other patient groups. Immunoglobulin G (IgG) purified from sera of patients with SLE with neutralizing anti-IFN-Abs impedes CpGC-driven IFNα-dependent differentiation of B cells into immature B cells and plasmablasts, thus recapitulating the neutralizing effect of anti-IFN-Abs on B cell differentiation in vitro. Our findings highlight a role for neutralizing anti-IFN-Abs in controlling SLE pathogenesis and support the use of IFN-targeting therapies in patients with SLE lacking neutralizing-anti-IFN-Abs.

Antibodies against type I IFN: The bad guys self-restrain in systemic lupus erythematosus

B cells and autoantibodies have well-described pathological roles in systemic lupus erythematosus (SLE). Bradford et al.¹ now provide evidence that autoantibodies can also be protective by neutralizing type I interferons (IFNs) and restraining the activation of pathogenic B cells.

High-titer anti-interferon-γ neutralizing autoantibodies linked to opportunistic infections in patients with adult-onset still's disease

Objective

Neutralizing anti-interferon (IFN)-γ autoantibodies are linked to opportunistic infections (OIs). To explore the association between anti-IFN-γ autoantibodies and OIs in patients with adult-onset Still's disease (AOSD), we aimed to examine the ability of these autoantibodies to blockade signal transducer and activator of transcription (STAT1)-phosphorylation and chemokines production.

Methods

Serum titers of anti-IFN-γ autoantibodies were quantified using ELISA in 29 AOSD and 22 healthy controls (HC). The detectable autoantibodies were verified with immunoblotting assay, and their neutralizing capacity against IFN-γ-signaling was evaluated with flow-cytometry analysis and immunoblotting. IFN-γ-mediated production of supernatant chemokines, including monocyte chemoattractant protein-1 (MCP-1) and IFN-γ inducible protein-10 (IP-10), were measured by ELISA.

Results

Among 29 AOSD patients, high titers of anti-IFN-γ neutralizing autoantibodies were detectable in two patients with OIs. Immunoblotting assay revealed more effective inhibition of STAT1-phosphorylation in THP-1 cells treated with sera from autoantibody-positive AOSD patients (56.7 ± 34.79%) compared with those from HC (104.3 ±29.51%), which was also demonstrated in flow-cytometry analysis (47.13 ± 40.99 vs. 97.92 ± 9.48%, p < 0.05). Depleted serum IgG from anti-IFN-γ autoAbs-positive AOSD patients with OIs restored phosphorylated STAT-1 upon IFN-γ treatment. Sera from autoantibody-positive AOSD patients more effectively inhibited IFN-γ-mediated production of MCP-1 (45.65 pg/ml) and IP-10 (22.44 pg/ml) than sera from HC (263.1 pg/ml and 104.0 pg/ml, both p < 0.05). Serum samples showing the strongest inhibition of IFN-γ-signaling were from two patients with high-titer autoantibodies and OIs.

Conclusion

AOSD patients have a high positive rate and titers of anti-IFN-γ autoantibodies. The remarkable blockade effect of high-titer autoantibodies on IFN-γ-mediated STAT1-phosphorylation and chemokines could make these patients susceptible to OIs.

Auto-antibodies against type I IFNs in > 10% of critically ill COVID-19 patients: a prospective multicentre study

BACKGROUND

Auto-antibodies (auto-Abs) neutralizing type I interferons (IFN) have been found in about 15% of critical cases COVID-19 pneumonia and less than 1% of mild or asymptomatic cases. Determining whether auto-Abs influence presentation and outcome of critically ill COVID-19 patients could lead to specific therapeutic interventions. Our objectives were to compare the severity at admission and the mortality of patients hospitalized for critical COVID-19 in ICU with versus without auto-Abs.

RESULTS

We conducted a prospective multicentre cohort study including patients admitted in 11 intensive care units (ICUs) from Great Paris area hospitals with proven SARS-CoV-2 infection and acute respiratory failure. 925 critically ill COVID-19 patients were included. Auto-Abs neutralizing type I IFN-α2, β and/or ω were found in 96 patients (10.3%). Demographics and comorbidities did not differ between patients with versus without auto-Abs. At ICU admission, Auto-Abs positive patients required a higher FiO₂ (100% (70-100) vs. 90% (60-100), p = 0.01), but were not different in other characteristics. Mortality at day 28 was not different between patients with and without auto-Abs (18.7 vs. 23.7%, p = 0.279). In multivariable analysis, 28-day mortality was associated with age (adjusted odds ratio (aOR) = 1.06 [1.04-1.08], p < 0.001), SOFA score (aOR = 1.18 [1.12-1.23], p < 0.001) and immunosuppression (aOR = 1.82 [1.1-3.0], p = 0.02), but not with the presence of auto-Abs (aOR = 0.69 [0.38-1.26], p = 0.23).

CONCLUSIONS

In ICU patients, auto-Abs against type I IFNs were found in at least 10% of patients with critical COVID-19 pneumonia. They were not associated with day 28 mortality.

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

BACKGROUND

Autoantibodies against type I interferons (IFN) alpha (α) and omega (ω), and interleukins (IL) 17 and 22 are a hallmark of autoimmune polyendocrine syndrome type 1 (APS-1), caused by mutations in the autoimmune regulator (AIRE) gene. Such antibodies are also seen in a number of monogenic immunodeficiencies.

OBJECTIVES

To determine whether screening for cytokine autoantibodies (anti-IFN-ω and anti-IL22) can be used to identify patients with monogenic immune disorders.

METHODS

A novel ELISA assay was employed to measure IL22 autoantibodies in 675 patients with autoimmune primary adrenal insufficiency (PAI) and a radio immune assay (RIA) was used to measure autoantibodies against IFN-ω in 1778 patients with a variety of endocrine diseases, mostly of autoimmune aetiology. Positive cases were sequenced for all coding exons of the AIRE gene. If no AIRE mutations were found, we applied next generation sequencing (NGS) to search for mutations in immune related genes.

RESULTS

We identified 29 patients with autoantibodies against IFN-ω and/or IL22. Of these, four new APS-1 cases with disease-causing variants in AIRE were found. In addition, we identified two patients with pathogenic heterozygous variants in CTLA4 and NFKB2, respectively. Nine rare variants in other immune genes were identified in six patients, although further studies are needed to determine their disease-causing potential.

CONCLUSION

Screening of cytokine autoantibodies can efficiently identify patients with previously unknown monogenic and possible oligogenic causes of autoimmune and immune deficiency diseases. This information is crucial for providing personalised treatment and follow-up of patients and their relatives.

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.

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-α2 alone (five patients) or with IFN-ω (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-α2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-ω. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients <70 yr of age (5.7 vs. 1.1%, P = 2.2 × 10-5), but not >70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-α2 and IFN-ω (OR = 11.7, P = 1.3 × 10-5), especially those <70 yr old (OR = 139.9, P = 3.1 × 10-10). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for ∼5% of cases of life-threatening influenza pneumonia in patients <70 yr old.

Autoantibodies in immunodeficiency syndromes: The Janus faces of immune dysregulation

Immunodeficiency syndromes represent a diverse group of inherited and acquired disorders, characterized by a spectrum of clinical manifestations, including recurrent infections, autoimmunity, lymphoproliferation and malignancy. Autoantibodies against various self-antigens reflect the immune dysregulation underlying these disorders, and could contribute to certain clinical findings, such as susceptibility to opportunistic infections, cytopenia of different hematopoietic lineages, and organ-specific autoimmune diseases. The mechanism of autoantibody production in the context of immunodeficiency remains largely unknown but is likely shaped by both intrinsic genetic aberrations and extrinsic exposures to possible infectious agents. These autoantibodies if harbor neutralizing activities and reach certain levels in the circulation, could disrupt the biological functions of their targets, resulting in specific clinical manifestations. Herein, we reviewed the prevalence of autoantibodies against cytokines, hematopoietic cells and organ-specific antigens in immunodeficiency syndromes and examined their associations with certain clinical findings. Moreover, the potential mechanism of autoantibody production was also discussed. These may shed light on the development of mechanism-based therapies to reset the dysregulated immune system in immunodeficient patients.

Clinical implications of host genetic variation and susceptibility to severe or critical COVID-19

Since the start of the coronavirus disease 2019 (COVID-19) pandemic, important insights have been gained into virus biology and the host factors that modulate the human immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 displays a highly variable clinical picture that ranges from asymptomatic disease to lethal pneumonia. Apart from well-established general risk factors such as advanced age, male sex and chronic comorbidities, differences in host genetics have been shown to influence the individual predisposition to develop severe manifestations of COVID-19. These differences range from common susceptibility loci to rare genetic variants with strongly predisposing effects, or proven pathogenic variants that lead to known or novel inborn errors of immunity (IEI), which constitute a growing group of heterogeneous Mendelian disorders with increased susceptibility to infectious disease, auto-inflammation, auto-immunity, allergy or malignancies. The current genetic findings point towards a convergence of common and rare genetic variants that impact the interferon signalling pathways in patients with severe or critical COVID-19. Monogenic risk factors that impact IFN-I signalling have an expected prevalence between 1 and 5% in young, previously healthy individuals (<60 years of age) with critical COVID-19. The identification of these IEI such as X-linked TLR7 deficiency indicates a possibility for targeted genetic screening and personalized clinical management. This review aims to provide an overview of our current understanding of the host genetic factors that predispose to severe manifestations of COVID-19 and focuses on rare variants in IFN-I signalling genes and their potential clinical implications.

Lower disease activity but higher risk of severe COVID-19 and herpes zoster in patients with systemic lupus erythematosus with pre-existing autoantibodies neutralising IFN-α

OBJECTIVES

Type-I interferons (IFNs-I) have potent antiviral effects. IFNs-I are also overproduced in patients with systemic lupus erythematosus (SLE). Autoantibodies (AAbs) neutralising IFN-α, IFN-β and/or IFN-ω subtypes are strong determinants of hypoxemic COVID-19 pneumonia, but their impact on inflammation remains unknown.

METHODS

We retrospectively analysed a monocentric longitudinal cohort of 609 patients with SLE. Serum AAbs against IFN-α were quantified by ELISA and functionally assessed by abolishment of Madin-Darby bovine kidney cell protection by IFN-α2 against vesicular stomatitis virus challenge. Serum-neutralising activity against IFN-α2, IFN-β and IFN-ω was also determined with a reporter luciferase activity assay. SARS-CoV-2 antibody responses were measured against wild-type spike antigen, while serum-neutralising activity was assessed against the SARS-CoV-2 historical strain and variants of concerns.

RESULTS

Neutralising and non-neutralising anti-IFN-α antibodies are present at a frequency of 3.3% and 8.4%, respectively, in individuals with SLE. AAbs neutralising IFN-α, unlike non-neutralising AAbs, are associated with reduced IFN-α serum levels and a reduced likelihood to develop active disease. However, they predispose patients to an increased risk of herpes zoster and severe COVID-19 pneumonia. Severe COVID-19 pneumonia in patients with SLE is mostly associated with combined neutralisation of different IFNs-I. Finally, anti-IFN-α AAbs do not interfere with COVID-19 vaccine humoral immunogenicity.

CONCLUSION

The production of non-neutralising and neutralising anti-IFN-I antibodies in SLE is likely to be a consequence of SLE-associated high IFN-I serum levels, with a beneficial effect on disease activity, yet a greater viral risk. This finding reinforces the recommendations for vaccination against SARS-CoV-2 in SLE.

Detection of Neutralizing Anti-Type 1 Interferon Autoantibodies

Autoantibodies (autoAbs) that neutralize type 1 interferons (T1IFNs) are a major risk factor associated with developing critical COVID-19 disease and are most commonly found in individuals over age 70 and in patients with genetic or acquired thymic defects. Swift identification of autoAb-positive individuals may allow targeted interventions to prevent critical COVID-19 disease. Herein, we provide a workflow and protocols aimed at rapidly identifying individuals who are autoAb positive from a large cohort. Basic Protocol 1 describes a multiplex particle-based assay to screen large cohorts of individuals for binding levels of anti-T1IFN autoAbs, and Basic Protocol 2 describes a functional assay to test if autoAbs in patient plasma can block T1IFN-induced JAK/STAT signaling. © Published 2022. This article is a U.S. Government work and is in the public domain in the USA. Basic Protocol 1: Multiplex particle-based bead assay to screen for binding levels of anti-type 1 interferon autoantibodies Alternate Protocol: Multiplex particle-based bead assay to screen for binding levels of anti-type 1 interferon immunoglobulin subtypes and isotypes Support Protocol: Coupling type 1 interferons (IFN-α, IFN-β, and IFN-ω) to magnetic beads Basic Protocol 2: pSTAT1 functional assay to test for neutralization activity of anti-type 1 interferon autoantibodies.

A comprehensive evaluation of the immune system response and type-I Interferon signaling pathway in hospitalized COVID-19 patients

BACKGROUND

The COVID-19 pandemic has become the world's main life-threatening challenge in the third decade of the twenty-first century. Numerous studies have been conducted on SARS-CoV2 virus structure and pathogenesis to find reliable treatments and vaccines. The present study aimed to evaluate the immune-phenotype and IFN-I signaling pathways of COVID-19 patients with mild and severe conditions.

MATERIAL AND METHODS

A total of 100 COVID-19 patients (50 with mild and 50 with severe conditions) were enrolled in this study. The frequency of CD4 + T, CD8 + T, Th17, Treg, and B lymphocytes beside NK cells was evaluated using flow cytometry. IFN-I downstream signaling molecules, including JAK-1, TYK-2, STAT-1, and STAT-2, and Interferon regulatory factors (IRF) 3 and 7 expressions at RNA and protein status were investigated using real-time PCR and western blotting techniques, respectively. Immune levels of cytokines (e.g., IL-1β, IL-6, IL-17, TNF-α, IL-2R, IL-10, IFN-α, and IFN-β) and the existence of anti-IFN-α autoantibodies were evaluated via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Immune-phenotyping results showed a significant decrease in the absolute count of NK cells, CD4 + T, CD8 + T, and B lymphocytes in COVID-19 patients. The frequency of Th17 and Treg cells showed a remarkable increase and decrease, respectively. All signaling molecules of the IFN-I downstream pathway and IRFs (i.e., JAK-1, TYK-2, STAT-1, STAT-2, IRF-3, and IRF-7) showed very reduced expression levels in COVID-19 patients with the severe condition compared to healthy individuals at both RNA and protein levels. Of 50 patients with severe conditions, 14 had anti-IFN-α autoantibodies in sera. Meanwhile, this result was 2 and 0 for patients with mild symptoms and healthy controls, respectively.

CONCLUSION

Our results indicate a positive association of the existence of anti-IFN-α autoantibodies and immune cells dysregulation with the severity of illness in COVID-19 patients. However, comprehensive studies are necessary to find out more about this context. Video abstract.

[Anti-cytokine autoantibodies: Review of the literature]

Anti-cytokine antibodies (ACA) are an emerging cause of acquired immunodeficiency, especially in previously healthy adults. The most frequently reported are anti-IFN-γ responsible for disseminated non-tuberculous mycobacteria infections, and anti-GM-CSF mainly in mycobacteria, cryptococcosis and nocardiosis infections. The presence of anti-IFN-α in severe COVID-19 infections has recently been described. The search for and detection of these ACAs in an unusual infection situation makes it possible to set up specific therapies in addition to the anti-infective treatment. ACAs are also frequent in various autoimmune pathologies where, in addition to being indicators of the breakdown of immune tolerance, they can modulate the activity of the disease according to their cytokine target. In this review of the literature, we will focus on the epidemiology and the clinical impact of these ACAs in healthy subjects and in infectious or dysimmune diseases.

Autoantibodies against IFNα in patients with systemic lupus erythematosus and susceptibility for infection: a retrospective case-control study

IFNα and anti-IFNα autoantibodies have been implicated in susceptibility both for systemic lupus erythematosus (SLE) and viral infection. We aimed to analyze the SLE disease phenotype and risk for infection associated with anti-IFN-α IgG autoantibodies in SLE patients In this multidisciplinary retrospective single referral center study, all consecutive patients with SLE admitted between January 1st and November 30th 2020 were considered. All subjects fulfilled the ACR/EULAR 2019 criteria for SLE. Anti-IFNα IgG autoantibodies were quantified at admission by ELISA. Demographic, medical history, laboratory, treatment, and outcome data were extracted from electronic medical records using a standardized data collection form. 180 patients [female 87.2%, median age of 44.4 (34-54.2) years] were included. The median disease duration was 10 years [4-20] with a median SLEDAI score of 2 [0-4] at study time. Fifty-four (30%) patients had a past-history of lupus nephritis. One hundred and forty-four (80%) had received long-term glucocorticoids and 99 (55%) immunosuppressive drugs. Overall, 127 infections-mostly bacterial and viral-were reported in 95 (52.8%) patients. Twenty SLE patients (11.1%) had positive anti-IFNα IgG autoantibodies with a titer ranging from 10 to 103 UA/mL. Age, sex, SLE phenotype and treatment did not significantly differ between SLE patients with or without anti-IFNα. Infection rate was similar in both groups except for tuberculosis which was more frequent in patients with anti-IFNα (20% vs. 3.1%, p = 0.01). The prevalence of autoantibodies against IFNα is high in SLE and associated with a higher frequency of tuberculosis.

BCG Infection in Patients With Inborn Errors of Immunity Receiving the Russian BCG Strain

BACKGROUND

Bacillus Calmette-Guierin (BCG) vaccination complications are common in inborn errors of immunity (IEI) due to the inability to clear live attenuated Mycobacterium bovis. Various BCG-vaccine strains are used worldwide, and the profile of the Russian BCG strain vaccine complications in IEI is poorly characterized.

OBJECTIVE

To evaluate risks of BCG infection in a large cohort of patients with IEI vaccinated with the Russian BCG strain.

METHODS

We evaluated 778 patients with IEI vaccinated with the Russian BCG strain.

RESULTS

A total of 114 (15%) developed BCG infection, 41 (36%) with local, 19 (17%) with regional, and 54 with (47%) disseminated disease. BCG infection was seen in 58% of the patients with severe combined immunodeficiency (SCID), 82% with chronic granulomatous disease, 50% with innate immune defects, 5% with combined immunodeficiency, and 2% with other IEI. BCG infection presented at a median age of 4 to 5 months in SCID, chronic granulomatous disease, combined immunodeficiency, and other IEI groups versus 12 months in patients with innate immune defects (P < .005). We found no influence of specific genetic defects, CD3⁺ and natural killer cell numbers in SCID, or dihydrorhodamine test stimulation index values in chronic granulomatous disease on the BCG-infection risks. All patients with SCID received antimycobacterial therapy at SCID diagnosis even in the absence of active BCG infection. More antimycobacterial agents were required in disseminated relative to local or regional infection (P < .0001). Only 1 of 114 patients (with SCID) died of BCG-related complications (<1%).

CONCLUSIONS

BCG infection is common in patients with IEI receiving BCG vaccination. Rational early antimycobacterial therapy, combined with anticytokine agents for posttransplant inflammatory syndrome prevention, and treatment in SCID may prevent BCG-related mortality.

Human autoantibodies underlying infectious diseases

The vast interindividual clinical variability observed in any microbial infection—ranging from silent infection to lethal disease—is increasingly being explained by human genetic and immunological determinants. Autoantibodies neutralizing specific cytokines underlie the same infectious diseases as inborn errors of the corresponding cytokine or response pathway. Autoantibodies against type I IFNs underlie COVID-19 pneumonia and adverse reactions to the live attenuated yellow fever virus vaccine. Autoantibodies against type II IFN underlie severe disease caused by environmental or tuberculous mycobacteria, and other intra-macrophagic microbes. Autoantibodies against IL-17A/F and IL-6 are less common and underlie mucocutaneous candidiasis and staphylococcal diseases, respectively. Inborn errors of and autoantibodies against GM-CSF underlie pulmonary alveolar proteinosis; associated infections are less well characterized. In individual patients, autoantibodies against cytokines preexist infection with the pathogen concerned and underlie the infectious disease. Human antibody-driven autoimmunity can interfere with cytokines that are essential for protective immunity to specific infectious agents but that are otherwise redundant, thereby underlying specific infectious diseases.

Cytokine autoantibodies in SARS-CoV-2 prepandemic and intrapandemic samples from an SLE cohort

Cytokine autoantibodies, particularly those directed to type I interferon (T1IFN), have been reported to portend an increased risk of severe COVID-19. Since SLE is one of the conditions historically associated with T1IFN autoantibodies, we sought to determine the prevalence of cytokine autoantibodies in our local cohort of 173 patients with SLE prepandemic and intrapandemic, of which nine had confirmed exposure to SARS-CoV-2. Autoantibodies to 16 different cytokines, including T1IFN, were measured by an addressable laser bead immunoassay. None of the 9 patients with confirmed exposure to SARS-CoV-2 had autoantibodies to T1IFN and none had severe COVID-19 symptoms, necessitating hospitalisation. Hence, we could not confirm that TIIFN autoantibodies increase the risk for severe COVID-19. In addition, the cytokine autoantibody pattern did not differ between those with and without evidence of SARS-CoV-2 exposure.

High-throughput identification of autoantibodies that target the human exoproteome

Autoantibodies that recognize extracellular proteins (the exoproteome) exert potent biological effects but are challenging to detect. Here, we developed rapid extracellular antigen profiling (REAP), a high-throughput technique for the comprehensive discovery of exoproteome-targeting autoantibodies. Patient samples are applied to a genetically barcoded yeast surface display library containing 2,688 human extracellular proteins. Antibody-coated yeast are isolated, and sequencing of barcodes is used to identify displayed antigens. To benchmark REAP's performance, we screened 77 patients with autoimmune polyglandular syndrome type 1 (APS-1). REAP sensitively and specifically detected both known and previously unidentified autoantibodies in APS-1. We further screened 106 patients with systemic lupus erythematosus (SLE) and identified numerous autoantibodies, several of which were associated with disease severity or specific clinical manifestations and exerted functional effects on cell signaling ex vivo. These findings demonstrate the utility of REAP to atlas the expansive landscape of exoproteome-targeting autoantibodies and their impacts on patient health outcomes.

Type I Interferons in Systemic Lupus Erythematosus: A Journey from Bench to Bedside

Dysregulation of type I interferons (IFNs) has been implicated in the pathogenesis of systemic lupus erythematosus (SLE) since the late 1970s. The majority of SLE patients demonstrate evidence of type I IFN pathway activation; however, studies attempting to address the relationship between type I IFN signature and SLE disease activity have yielded conflicting results. In addition to type I IFNs, type II and III IFNs may overlap and also contribute to the IFN signature. Different genetic backgrounds lead to overproduction of type I IFNs in SLE and contribute to the breakdown of peripheral tolerance by activation of antigen-presenting myeloid dendritic cells, thus triggering the expansion and differentiation of autoreactive lymphocytes. The consequence of the continuous stimulation of the immune system is manifested in different organ systems typical of SLE (e.g., mucocutaneous and cardiovascular involvement). After the discovery of the type I IFN signature, a number of different strategies have been developed to downregulate the IFN system in SLE patients, finally leading to the successful trial of anifrolumab, the second biologic to be approved for the treatment of SLE in 10 years. In this review, we will discuss the bench to bedside translation of the type I IFN pathway and put forward some issues that remain unresolved when selecting SLE patients for treatment with biologics targeting type I IFNs.

Human genetic and immunological determinants of critical COVID-19 pneumonia

SARS-CoV-2 infection is benign in most individuals but, in _˜10% of cases, it triggers hypoxemic COVID-19 pneumonia, which becomes critical in _˜3% of cases. The ensuing risk of death (_˜1%) doubles every five years from childhood onward and is _˜1.5 times greater in men than in women. What are the molecular and cellular determinants of critical COVID-19 pneumonia? Inborn errors of type I IFNs, including autosomal TLR3 and X-linked TLR7 deficiencies, are found in _˜1-5% of patients with critical pneumonia under 60 years old, and a lower proportion in older patients. Pre-existing autoantibodies neutralizing IFN-α, -β, and/or -ω, which are more common in men than in women, are found in _˜15-20% of patients with critical pneumonia over 70 years old, and a lower proportion in younger patients. Thus, at least 15% of cases of critical COVID-19 pneumonia can apparently be explained. The TLR3- and TLR7-dependent production of type I IFNs by respiratory epithelial cells and plasmacytoid dendritic cells, respectively, is essential for host defense against SARS-CoV-2. In ways that can depend on age and sex, insufficient type I IFN immunity in the respiratory tract during the first few days of infection may account for the spread of the virus, leading to pulmonary and systemic inflammation.

Autoantibodies Neutralizing Type I Interferons in 20% of COVID-19 Deaths in a French Hospital

Recent studies reported the presence of pre-existing autoantibodies (auto-Abs) neutralizing type I interferons (IFNs) in at least 15% of patients with critical COVID-19 pneumonia. In one study, these auto-Abs were found in almost 20% of deceased patients across all ages. We aimed to assess the prevalence and clinical impact of the auto-Abs to type I IFNs in the Seine-Saint-Denis district, which was one of the most affected areas by COVID-19 in France during the first wave. We tested for the presence of auto-Abs neutralizing type I IFNs in a cohort of patients admitted for critical COVID-19 pneumonia during the first wave in the spring of 2020 in the medicine departments at Robert Ballanger Hospital, Aulnay sous Bois. We found circulating auto-Abs that neutralized 100 pg/mL IFN-α2 and/or IFN-ω in the plasma (diluted 1/10) of 7.9% (11 of 139) of the patients hospitalized for critical COVID-19. The presence of neutralizing auto-Abs was associated with an increased risk of mortality, as these auto-Abs were detected in 21% of patients who died from COVID-19 pneumonia. Deceased patients with and without auto-Abs did not present overt clinical differences. These results confirm both the importance of type I IFN immunity in host defense against SARS-CoV-2 infection and the usefulness of detection of auto-Abs neutralizing type I IFNs in the management of patients.

Anti-Interferon Autoantibodies in Adult-Onset Immunodeficiency Syndrome and Severe COVID-19 Infection

Adult-onset immunodeficiency syndrome due to anti-interferon (IFN)-γ autoantibodies has attracted much attention in recent years. It usually occurs in previously healthy people and usually presents as chronic, recurrent, and hard-to-control infections that can be effectively treated with aggressive antibiotic therapy. Adult-onset immunodeficiency syndrome is also referred to as AIDS-like syndrome. Anti-type I IFN (IFN-I) autoantibodies have been reported to play a significant role in the pathogenesis of coronavirus disease 2019 (COVID-19) and preexisting anti-IFN-I autoantibodies are associated with an increased risk of severe COVID-19. This review summarizes the effects of anti-IFN autoantibodies on the susceptibility and severity of various infectious diseases, including SARS-CoV-2 infection. In addition, we discuss the role of anti-IFN autoantibodies in the pathogenesis of autoimmune diseases that are characterized by recurrent infections.