Autoantibody to interferon-gamma associated with adult-onset immunodeficiency in non-HIV individuals in Northern Thailand

The ouroboros of autoimmunity

Human autoimmunity against elements conferring protective immunity can be symbolized by the 'ouroboros', a snake eating its own tail. Underlying infection is autoimmunity against three immunological targets: neutrophils, complement and cytokines. Autoantibodies against neutrophils can cause peripheral neutropenia underlying mild pyogenic bacterial infections. The pathogenic contribution of autoantibodies against molecules of the complement system is often unclear, but autoantibodies specific for C3 convertase can enhance its activity, lowering complement levels and underlying severe bacterial infections. Autoantibodies neutralizing granulocyte-macrophage colony-stimulating factor impair alveolar macrophages, thereby underlying pulmonary proteinosis and airborne infections, type I interferon viral diseases, type II interferon intra-macrophagic infections, interleukin-6 pyogenic bacterial diseases and interleukin-17A/F mucocutaneous candidiasis. Each of these five cytokine autoantibodies underlies a specific range of infectious diseases, phenocopying infections that occur in patients with the corresponding inborn errors. In this Review, we analyze this ouroboros of immunity against immunity and posit that it should be considered as a factor in patients with unexplained infection.

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.

From Mendel to mycoses: Immuno-genomic warfare at the human-fungus interface

Fungi are opportunists: They particularly require a defect of immunity to cause severe or disseminated disease. While often secondary to an apparent iatrogenic cause, fungal diseases do occur in the absence of one, albeit infrequently. These rare cases may be due to an underlying genetic immunodeficiency that can present variably in age of onset, severity, or other infections, and in the absence of a family history of disease. They may also be due to anti-cytokine autoantibodies. This review provides a background on how human genetics or autoantibodies underlie cases of susceptibility to severe or disseminated fungal disease. Subsequently, the lessons learned from these inborn errors of immunity marked by fungal disease (IEI-FD) provide a framework to begin to mechanistically decipher fungal syndromes, potentially paving the way for precision therapy of the mycoses.

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.

Anticytokine Autoantibodies in Infectious Diseases: A Practical Overview

Anticytokine autoantibodies (ACAAs) are a fascinating group of antibodies that have gained more and more attention in the field of autoimmunity and secondary immunodeficiencies over the years. Some of these antibodies are characterized by their ability to target and neutralize specific cytokines. ACAAs can play a role in the susceptibility to several infectious diseases, and their infectious manifestations depending on which specific immunological pathway is affected. In this review, we will give an outline per infection in which ACAAs might play a role and whether additional immunomodulatory treatment next to antimicrobial treatment can be considered. Finally, we describe the areas for future research on ACAAs.

Prevalence and clinical manifestations of cutaneous findings in patients with adult-onset immunodeficiency due to anti-interferon gamma autoantibodies: an eight-year retrospective study

BACKGROUND

Cutaneous findings in adult-onset immunodeficiency due to anti-interferon gamma autoantibodies (anti-IFN-γ autoAbs) are common. Currently, data on this topic are scarce.

METHODS

We retrospectively reviewed medical records of 202 skin episodes from 77 patients diagnosed with adult-onset immunodeficiency due to anti-IFN-γ autoAbs. The exclusion of drug eruptions left 180 episodes from 74 patients for further analysis.

RESULTS

Reactive dermatosis was diagnosed in 66.1%, followed by disseminated skin infection (18.3%) and local skin infection (15.6%). Neutrophilic dermatosis (ND) tended to appear on the upper part of bodies, while leg lesions were common in the non-ND. Disseminated infection occurred more frequently with ND. Mycobacterium abscessus was the most common pathogen of concomitant infection. Remission was achieved in 21.6% and was significantly associated with females.

CONCLUSION

Reactive dermatosis was the most common skin manifestation. ND was found in the upper part of bodies and associated with disseminated infection. Drug-free remission was scarcely achieved.

Intracranial infection accompanied sweet’s syndrome in a patient with anti-interferon-γ autoantibodies: A case report

BACKGROUND

Several reports of adult-onset immunodeficiency syndrome have been associated with anti-interferon-gamma (IFN-γ) autoantibodies (AIGAs). However, it is rare to find AIGAs with intracranial infections.

CASE SUMMARY

In this case study, we report a case of an AIGAs with intracranial infection and hand rashes considered Sweet’s syndrome. The patient presented to our hospital with a persistent cough, a fever that had been going on for 6 mo, and a rash that had been going on for a week. The patient started losing consciousness gradually on the fourth day after admission, with neck stiffness and weakened limb muscles. The upper lobe of the left lung had a high-density mass with no atypia and a few inflammatory cells in the interstitium. Brain magnetic resonance imaging and cerebrospinal fluid suggest intracranial infection. The pathology of the skin damage on the right upper extremity revealed an infectious lesion that was susceptible to Sweet’s disease. It has an anti-IFN-γ autoantibody titer of 1:2500. She was given empirical anti-non-tuberculous mycobacterial and antifungal treatments. The patient had no fever, obvious cough, headache, or rash on the hand. She got out of bed and took care of herself following hospitalization and discharge with medicine.

CONCLUSION

Adults with severe and recurrent infections of several organs should be considered for AIGAs if no other known risk factors exist. AIGAs are susceptible to subsequent intracranial infections and Sweet’s syndrome.

Cellular mechanisms and clinical applications for phenocopies of inborn errors of immunity: infectious susceptibility due to cytokine autoantibodies

INTRODUCTION

With a growing knowledge of Inborn error immunity (IEI), immunological profiling and genetic predisposition to IEI phenocopies have been developed in recent years.

AREAS COVERED

Here we summarized the correlation between various pathogen invasions, autoantibody profiles, and corresponding clinical features in the context of patients with IEI phenocopies. It has been extensively evident that patients with anti-cytokine autoantibodies underly impaired anti-pathogen immune responses and lead to broad unregulated inflammation and tissue damage. Several hypotheses of anti-cytokine autoantibodies production were summarized here, including a defective negative selection of autoreactive T cells, abnormal germinal center formation, molecular mimicry, HLA class II allele region, lack of auto-reactive lymphocyte apoptosis, and other possible hypotheses.

EXPERT OPINION

Phenocopies of IEI associated with anti-cytokine autoantibodies are increasingly recognized as one of the causes of acquired immunodeficiency and susceptibility to certain pathogen infections, especially facing the current challenge of the COVID-19 pandemic. By investigating clinical, genetic, and pathogenesis autoantibodies profiles associated with various pathogens' susceptibilities, we could better understand the IEI phenocopies with anti-cytokine autoantibodies, especially for those that underlie life-threatening SARS-CoV-2.

Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases

In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.

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.

Case Report: Invasive Cryptococcosis in French Guiana: Immune and Genetic Investigation in Six Non-HIV Patients

Objectives

We describe the clinical, mycological, immunological, and genetic characteristics of six HIV-negative patients presenting with invasive cryptococcosis.

Methods

Patients with cryptococcosis without any of the classical risk factors, such as HIV infection, followed at Cayenne Hospital, were prospectively included. An immunologic and genetic assessment was performed.

Results

Five male patients and one female patient, 5 adults and one child, were investigated. All presented a neuromeningeal localization. Cryptococcus neoformans var. gattii and C. neoformans var. grubii were isolated in two and three patients, respectively, whereas one patient could not be investigated. Overall, we did not observe any global leukocyte defect. Two patients were found with high levels of circulating autoantibodies against Granulocyte macrophage-colony stimulating factor (GM-CSF), and none had detectable levels of autoantibodies against Interferon gamma (IFN-γ) Sequencing of STAT1 exons and flanking regions performed for four patients was wild type.

Conclusion

To better understand cryptococcosis in patients with cryptococcosis but otherwise healthy, further explorations are needed with repeated immune checkups and strain virulence studies.

Determination of a distinguished interferon gamma epitope recognized by monoclonal antibody relating to autoantibody associated immunodeficiency

Anti-interferon gamma autoantibodies (anti-IFN-γ autoAbs) neutralize the IFN-γ-mediated functions, contributing to immunodeficiency. A particular autoAb in patient serum had been previously demonstrated to recognize the same determinant on IFN-γ as the neutralizing anti-IFN-γ monoclonal antibody clone B27 (B27 mAb). This study explored the epitope recognized by B27 mAb. The specific peptide sequence recognized by B27 mAb, TDFLRMMLQEER, was retrieved from a phage display random peptide library. Sequence alignment and homology modeling demonstrated that the queried phage peptide sequence and structure were similar to amino acids at position 27–40 (TLFLGILKNWKEES) of the human IFN-γ. This determinant resides in the contact surface of IFN-γ and interferon gamma receptor 1. To elucidate the crucial amino acids, mutations were introduced by substituting T27 and T27F29L30 with alanine or deleting the amino acid residues T27–L33. The binding of B27 mAb to IFN-γ T27A using western blotting was lesser than that to wild-type. The interaction with triple mutant and T27–L33 deletion mutant using western blotting and sandwich ELISA was abolished. The finding demonstrated that T27, F29, and L30 are critical residues in the B27 antigenic determinant. Identification of the functional domain of IFN-γ decrypted the relevance of neutralizing autoAb in adult-onset immunodeficiency.

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.

Talaromyces marneffei Infection: Virulence, Intracellular Lifestyle and Host Defense Mechanisms

Talaromycosis (Penicilliosis) is an opportunistic mycosis caused by the thermally dimorphic fungus Talaromyces (Penicillium) marneffei. Similar to other major causes of systemic mycoses, the extent of disease and outcomes are the results of complex interactions between this opportunistic human pathogen and a host’s immune response. This review will highlight the current knowledge regarding the dynamic interaction between T. marneffei and mammalian hosts, particularly highlighting important aspects of virulence factors, intracellular lifestyle and the mechanisms of immune defense as well as the strategies of the pathogen for manipulating and evading host immune cells.

Immunodeficiency and Autoantibodies to Cytokines

BACKGROUND

Anti-cytokine autoantibodies (AAbs) associated with an infectious phenotype are now included along with anti-complement AAbs and somatic pathogenic gene variants as a distinct category termed 'phenocopies of primary immunodeficiencies' in the classification of inborn errors of immunity. Anti-cytokine AAbs target specific cytokine pathways, leading to inordinate susceptibility to specific organisms, generally in the setting of immunocompetence.

CONTENT

Anti-cytokine AAbs are detected in the majority of healthy individuals and may play a regulatory role in limiting exaggerated responses to cytokines. While it is not well understood why some individuals with anti-cytokine AAbs develop increased susceptibility to organisms of low pathogenicity and others do not, it is likely that genetics and environment play a role. To date, AAbs to interferon gamma (IFNγ), interferon alpha (IFNα), interleukins-17 and 22 (IL-17/IL-22), interleukin-6 and granulocyte macrophage colony stimulating factor (GM-CSF) and their association with increased susceptibility to nontuberculous mycobacteria and other intracellular organisms, viral infections, Candida albicans, Staphylococcus aureus and other pyogenic organisms, and fungal infections respectively, have been described. The clinical phenotype of these patients is very similar to that of individuals with pathogenic gene variants in the specific cytokine pathway that the autoantibody targets, hence the term 'phenocopy.' Recognition of anti-cytokine AAbs as a distinct cause of immunodeficiency or immune dysregulation is important for appropriate management of such patients.

SUMMARY

Understanding the roles that anti-cytokine AAbs play in health and disease continues to be a fascinating area of research. Evaluating generally immunocompetent individuals who present with chronic, treatment refractory, or unusual infections for anti-cytokine AAbs is critical as it may direct therapy and disease management.

Targeting interferon-γ in hyperinflammation: opportunities and challenges

Interferon-γ (IFNγ) is a pleiotropic cytokine with multiple effects on the inflammatory response and on innate and adaptive immunity. Overproduction of IFNγ underlies several, potentially fatal, hyperinflammatory or immune-mediated diseases. Several data from animal models and/or from translational research in patients point to a role of IFNγ in hyperinflammatory diseases, such as primary haemophagocytic lymphohistiocytosis, various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome, and cytokine release syndrome, all of which are often managed by rheumatologists or in consultation with rheumatologists. Given the effects of IFNγ on B cells and T follicular helper cells, a role for IFNγ in systemic lupus erythematosus pathogenesis is emerging. To improve our understanding of the role of IFNγ in human disease, IFNγ-related biomarkers that are relevant for the management of hyperinflammatory diseases are progressively being identified and studied, especially because circulating levels of IFNγ do not always reflect its overproduction in tissue. These biomarkers include STAT1 (specifically the phosphorylated form), neopterin and the chemokine CXCL9. IFNγ-neutralizing agents have shown efficacy in the treatment of primary haemophagocytic lymphohistiocytosis in clinical trials and initial promising results have been obtained in various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome. In clinical practice, there is a growing body of evidence supporting the usefulness of circulating CXCL9 levels as a biomarker reflecting IFNγ production.

Morphologic Spectrum of Lymphadenopathy in Adult-onset Immunodeficiency (Anti-interferon-γ Autoantibodies)

Adult-onset immunodeficiency syndrome (AOIS) caused by anti-interferon-γ autoantibodies is an emerging disease. Affected patients present typically with systemic lymphadenopathy, fatigue, and fever. We studied 36 biopsy specimens, 31 lymph nodes, and 5 extranodal sites, of AOIS confirmed by serum autoantibody or QuantiFERON-TB Gold In-Tube assay. We describe the morphologic features and the results of ancillary studies, including special stains, immunohistochemistry, and molecular testing. The overall median age of these patients was 60.5 years (range, 41 to 83 y) with a male-to-female ratio of 20:16. All biopsy specimens showed nontuberculous mycobacterial infection, and most cases showed the following histologic features: capsular thickening with intranodal sclerosing fibrosis, irregularly distributed ill-formed granulomas or histiocytic aggregates with neutrophilic infiltration, interfollicular expansion by a polymorphic infiltrate with some Hodgkin-like cells that commonly effaces most of the nodal architecture and proliferation of high endothelial venules. In situ hybridization analysis for Epstein-Barr virus-encoded RNA showed scattered (<1%) to relatively more common (4% to 5%) positive cells in 29 of 30 (97%) tested specimens, reflecting immune dysregulation due to an interferon-γ defect. In the 31 lymph node specimens, 23 (74%) cases showed increased immunoglobulin G4-positive plasma cells (4 to 145/HPF; mean, 49.7/HPF) with focal areas of sclerosis reminiscent of immunoglobulin G4-related lymphadenopathy, 4 (13%) cases resembled, in part, nodular sclerosis Hodgkin lymphoma, and 9 (29%) cases mimicked T-cell lymphoma. Among 33 patients with available clinical follow-up, 20 (61%) showed persistent or refractory disease despite antimycobacterial therapy, and 1 patient died of the disease. We conclude that the presence of ill-defined granulomas, clusters of neutrophils adjacent to the histiocytic aggregates, and some Epstein-Barr virus-positive cells are features highly suggestive of AOIS. A high index of clinical suspicion and awareness of the morphologic features and differential diagnosis of AOIS are helpful for establishing the diagnosis.

Adult-onset immunodeficiency due to anti-interferon-gamma autoantibody-associated Sweet syndrome: A distinctive entity

Sweet syndrome (SS) has been increasingly reported in patients with adult-onset immunodeficiency (AOID) due to anti-interferon-γ autoantibody who also have concomitant opportunistic infections, especially disseminated non-tuberculous mycobacterial infection (dNTMI). A retrospective study retrieving data from 2011 through 2020 was conducted. We compared clinical characteristics of SS with and without AOID and generated the prediction model and examined the interaction between AOID and dNTMI in the occurrence of SS. Lymphadenopathy, pustular lesions, and leukocytosis are the significant predictors for AOID-associated SS. Adjusted risk differences were 0.58 (95% confidence interval [CI], 0.33-0.83), 0.21 (95% CI, 0.02-0.39), and 0.24 (95% CI, 0.01-0.47), respectively. Based on the analysis of aggregated cross-sectional data, both the overall and the direct effect of AOID increased the prevalence of SS. The indirect effect of AOID on the occurrence of SS might also be mediated through dNTMI or other common opportunistic infections. In addition, there was a trend of positive additive interaction between AOID and dNTMI. Although the test of additive interaction did not reveal statistically significant results, a deviation from additivity of isolated effects might suggest potential causal interaction between AOID and dNTMI. The distinctive clinical syndrome comprising lymphadenopathy, pustular lesions, and leukocytosis in patients with SS should raise the awareness of clinicians to the potential of underlying AOID.

Application of QuantiFERON ELISA for Detection of Interferon-Gamma Autoantibodies in Adult-Onset Immunodeficiency Syndrome

OBJECTIVE

Patients who develop interferon-gamma autoantibodies (IFN-ɤ autoAbs) in adult-onset immunodeficiency (AOID) syndrome are more likely to develop opportunistic and recurrent intracellular infections. The assay to detect IFN-ɤ autoAbs is essential for the diagnosis and therapeutic monitoring of AOID syndrome. Therefore, this study applied the QuantiFERON assay for the detection of IFN-ɤ autoAbs.

METHODS

Serum from patients with AOID syndrome (n = 19) and serum from healthy patients (n = 20) was collected and applied using 2 neutralizing platforms of enzyme-linked immunosorbent assay (ELISA) kits (the BD ELISA and the QuantiFERON ELISA) for IFN-ɤ autoAbs detection.

RESULTS

The pooled serum from patients with AOID syndrome showed >50% inhibition at 1:5000 dilution (positive), whereas the pooled serum from healthy patients showed <50% inhibition at 1:5000 dilution (negative) according to the neutralizing QuantiFERON ELISA. Each specimen showed the same result according to both the neutralizing BD ELISA and the neutralizing QuantiFERON ELISA. Moreover, the patient serum showed a variation in titer ranging from 1:5000 to >1:5,000,000 according to the neutralizing QuantiFERON ELISA.

CONCLUSION

The QuantiFERON ELISA kit could be applied for the detection of IFN-ɤ autoAbs for the diagnosis and therapeutic monitoring of AOID syndrome.

Anti-interferon-γ autoantibody-associated immunodeficiency

Anticytokine autoantibodies are an emerging disease etiology, through the disturbance of physiological functions of cognate cytokines. Anti-interferon (IFN)-γ autoantibodies (AIGAs) were first identified in patients with severe mycobacterial infections, and were considered to be an autoimmune phenocopy of inborn genetic errors of the IL-12/IFN-γ axis. More than 600 reported cases, most originating from Southeast Asia, have been diagnosed over the last decade. Specific HLA class II molecules are associated with these autoantibodies, which provide a genetic basis for the high prevalence of this immunodeficiency syndrome in certain ethnic groups. Salmonellosis and herpes zoster reactivation are observed in more than half the patients with AIGAs. Moreover, AIGAs have been shown to underlie severe Taralomyce marneffei infection in HIV-negative patients. AIGAs may, thus, be considered a new form of late-onset immunodeficiency conferring a predisposition not only to severe mycobacterial, but also to some bacterial and fungal infections.

Clinical findings of Talaromyces marneffei infection among patients with anti-interferon-γ immunodeficiency: a prospective cohort study

Background

Talaromyces marneffei (T. marneffei) infection has been associated with adult-onset immunodeficiency due to anti-IFN-γ autoantibodies. We aimed to investigate the clinical features of non-HIV-infected patients with T. marneffei infection in southern China.

Methods

Between January 2018 and September 2020, we enrolled patients with T. marneffei infection who were HIV-negative (group TM, n = 42), including anti-IFN-γ autoantibody-positive (group TMP, n = 22) and anti-IFN-γ autoantibody-negative (group TMN, n = 20) patients and healthy controls (group HC, n = 40). Anti-IFN-γ autoantibodies were detected by ELISA. Clinical characteristics and clinical laboratory parameters were recorded.

Results

Compared with anti-IFN-γ autoantibody-negative patients with T. marneffei infection, anti-IFN-γ autoantibody-positive patients did not have underlying respiratory disease; more frequently exhibited dissemination of systemic infections with severe pleural effusion; had higher WBC counts, C-reactive protein levels, erythrocyte sedimentation rates, and neutrophil and CD8⁺ T cell counts; had lower hemoglobin levels; and were more likely to have other intracellular pathogen infections. Most of these patients had poor outcomes despite standardized antimicrobial therapy.

Conclusion

T. marneffei-infected patients with higher anti-IFN-γ autoantibody titers have more severe disease and complex clinical conditions.

Talaromycosis marneffei of the Cervical Spine: An Unusual Infection

Talaromyces marneffei infection (TMI) causing vertebral osteomyelitis of the cervical spine is extremely rare. TMI in an HIV-uninfected patient is also unusual. This report presents the successful treatment of an HIV-uninfected TMI patient who underwent C6 and T1 vertebrectomies, bone grafting, and anterior cervical plating accompanied by antifungal therapy. A 63-year-old woman was diagnosed with adult-onset immune deficiency. She suddenly developed progressive neck pain without neurologic deficit. The plain radiographs and magnetic resonance imaging showed inflammation and abscess formation along the prevertebral area from C3-4 to T2-3 with vertebral body destruction. Intraoperative pus culture and tissue specimens were determined to be T marneffei. The patient was treated intravenously with amphotericin B deoxycholate for 4 weeks (0.6 mg/kg/d) and oral itraconazole (400 mg/d) for 12 months. Over a 2 consecutive year follow-up period, she achieved a full recovery with an absence of neck pain.

Latticed Gold Nanoparticle Conjugation via Monomeric Streptavidin in Lateral Flow Assay for Detection of Autoantibody to Interferon-Gamma

Adult-onset immunodeficiency syndrome (AOID) patients with autoantibodies (autoAbs) against interferon-gamma (IFN-γ) generally suffer from recurrent and recalcitrant disseminated non-tuberculous mycobacterial diseases. Since the early stages of AOID do not present specific symptoms, diagnosis and treatment of the condition are not practical. A simplified diagnostic method for differentiating AOID from other immunodeficiencies, such as HIV infection, was created. Anti-IFN-γ is generally identified using enzyme-linked immunosorbent assay (ELISA), which involves an instrument and a cumbersome process. Recombinant IFN-γ indirectly conjugated to colloidal gold was used in the modified immunochromatographic (IC) strips. The biotinylated-IFN-γ was incorporated with colloidal-gold-labeled 6HIS-maltose binding protein-monomeric streptavidin (^6HISMBP-mSA) and absorbed at the conjugate pad. The efficacy of the IC strip upon applying an anti-IFN-γ autoAb cut-off ELISA titer of 2500, the sensitivity and specificity were 84% and 90.24%, respectively. When a cut-off ELISA titer of 500 was applied, the sensitivity and specificity were 73.52% and 100%, respectively.

Minireview: Insights into anti-interferon-γ autoantibodies

The association between the presence of anti-interferon-γ autoantibodies and the onset of immunodeficiency with intracellular infections has been clearly established. No standard regimen to control the production of these pathogenic autoantibodies, apart from antimicrobial therapy to eliminate infections, contributes to the medical burden of this syndrome, which sometimes has a fatal outcome. In this review, we summarize the findings on anti-interferon-γ autoantibodies to facilitate further research and to provide guidance for treatment strategies.

Evaluation of plasma anti-GPL-core IgA and IgG for diagnosis of disseminated non-tuberculous mycobacteria infection

Detection of IgA antibody against Mycobacterium avium complex (MAC) glycopeptidolipid (GPL) has recently been shown to improve the diagnosis of MAC pulmonary disease but has yet to be tested in disseminated Non-tuberculous mycobacteria (NTM) infection. In this study, we address the diagnostic efficacies of an anti-GPL-core ELISA kit in disseminated lymphadenopathy patients positive for NTM culture and anti-IFN-γ autoantibodies. The study was conducted in a tertiary referral center in northeastern Thailand and patients with NTM, tuberculosis, melioidosis, and control subjects were enrolled. Plasma immunoglobulin A (IgA) and G (IgG) antibodies against GPL-core were detected in the subjects and the specificity and sensitivity of the assay was assessed. Anti-GPL-core IgA and IgG levels were significantly higher in NTM patients than other groups (p < 0.0001). Diagnostic efficacy for NTM patients using anti-GPL-core IgA cut-off value of 0.352 U/ml showed good sensitivity (91.18%) and intermediate specificity (70.15%). Using a cut-off value of 4.140 AU/ml for anti-GPL-core IgG showed the same sensitivity (91.18%) with increased specificity (89.55%) and an 81.58% positive predictive value. Most patients with moderate levels (4.140–7.955 AU/ml) of anti-GPL-core IgG had rapidly growing mycobacteria (RGM) infection. Taken together, the detection of anti-GPL-core antibodies could provide a novel option for the diagnosis and management of disseminated NTM infected patients.

Diagnosis of NTM active infection in lymphadenopathy patients with anti-interferon-gamma auto-antibody using inhibitory ELISA vs. indirect ELISA

The anti-interferon-gamma (IFN-gamma) autoantibody is a known cause of opportunistic non-tuberculous mycobacterial (NTM) infection in adults. Diagnosis of those patients is difficult due to the low sensitivity of bacterial culture, and because detection of the neutralizing autoantibody needs special laboratory devices. We conducted a retrospective review of indirect and inhibitory ELISA, both used for detection of anti-IFN-gamma auto-antibody in 102 patients with lymphadenopathies. We assessed hospital records of NTM isolation and/or diagnosis of NTM infection. The review revealed the compatible sensitivity and superior specificity and predictive values for inhibitory ELISA over against indirect ELISA—the latter achieving 100% specificity and positive predictive value for diagnosis of NTM infection in patients with lymphadenopathies. The results confirm functional assays that show plasma samples from NTM-infected patients with positive results by either indirect and/or inhibitory ELISA are IFN-gamma neutralizing autoantibodies. The inhibitory titer of anti-IFN-gamma auto-antibody can be used to distinguish patients with active from inactive NTM infection. Inhibitory ELISA is thus a practical, rapid, high performance tool for routine detection of anti-IFN-gamma autoantibody and NTM infection diagnosis before confirmation, enabling a timely therapeutic strategy for active infection treatment.

Autoantibodies against cytokines: phenocopies of primary immunodeficiencies?

Anti-cytokine autoantibodies may cause immunodeficiency and have been recently recognized as ‘autoimmune phenocopies of primary immunodeficiencies’ and are found in particular, but not exclusively in adult patients. By blocking the cytokine’s biological function, patients with anti-cytokine autoantibodies may present with a similar clinical phenotype as the related inborn genetic disorders. So far, autoantibodies to interferon (IFN)-γ, GM-CSF, to a group of TH-17 cytokines and to IL-6 have been found to be causative or closely associated with susceptibility to infection. This review compares infectious diseases associated with anti-cytokine autoantibodies with primary immunodeficiencies affecting similar cytokines or related pathways.

Efficacy of acitretin in the treatment of reactive neutrophilic dermatoses in adult-onset immunodeficiency due to interferon-gamma autoantibody

Reactive neutrophilic dermatoses in adult‐onset immunodeficiency due to interferon‐γ autoantibody (AOID) are usually associated with concomitant active opportunistic infections. Data focusing on the treatment of these dermatoses with non‐immunosuppressive drugs are still lacking. The aim of this study was to assess the efficacy and safety of acitretin treatment of reactive neutrophilic dermatoses in AOID. We conducted a retrospective review of all patients with AOID who had reactive neutrophilic dermatoses and had been treated with acitretin from January 2008 to December 2018. In total, 23 patients had been diagnosed with AOID, with 27 episodes of reactive neutrophilic dermatoses (20 episodes of Sweet syndrome and seven episodes of generalized pustular eruption) and treated with acitretin. The median effective dose of acitretin was 10 mg/day. The mean initial response was 5.6 ± 2.3 days. The rash had almost or completely cleared within 2 weeks in 70.4% of patients. One case had developed a reversible acitretin‐induced liver injury with hepatocellular pattern. The median total duration of treatment was 3 months. In conclusion, this study demonstrates the potential role of acitretin as one of the treatments of choice for reactive neutrophilic dermatoses in AOID, attributable to its favorable response and good tolerability.

Triple infection with Cryptococcus, varicella-zoster virus, and Mycobacterium abscessus in a patient with anti-interferon-gamma autoantibodies: a case report

Background

The most common infection in patients positive for anti-interferon-gamma autoantibodies (anti-IFN-γ AAbs) is disseminated nontuberculous mycobacterial (dNTM) infection. Here, we report a rare case of triple infection caused by Cryptococcus, varicella-zoster virus (VZV), and nontuberculous mycobacterium in a patient with anti-IFN-γ AAbs.

Case presentation

A 53-year-old Thai man presented with a progressively enlarging right cervical mass with low-grade fever and significant weight loss for 4 months. He also developed a lesion at his left index finger. A biopsy of that lesion showed granulomatous inflammation with yeast-like organisms morphologically consistent with cryptococcosis. Serum cryptococcal antigen was positive. Histopathology of a right cervical lymph node revealed chronic granulomatous lymphadenitis, and the lymph node culture grew Mycobacterium abscessus. One month later, he complained of vision loss in his left eye and subsequently developed a group of painful vesicles at the right popliteal area of S1 dermatome. Lumbar puncture was performed and his cerebrospinal fluid was positive for VZV DNA. His blood test for anti-HIV antibody was negative. Anti-IFN-γ AAbs was positive, but test for anti-granulocyte-macrophage colony-stimulating factor autoantibodies (anti-GM-CSF AAbs) was negative. He was treated with amphotericin B plus fluconazole for cryptococcosis; a combination of amikacin, imipenem, azithromycin, and levofloxacin for dNTM infection; and, intravenous acyclovir for disseminated VZV infection. After treatment, our patient’s fever and cervical lymphadenopathy were subsided, and his vision and visual acuity were both improved.

Conclusions

This is the first case of triple infection with cryptococcosis, VZV, and dNTM in a patient who tested positive for anti-IFN-γ AAbs and negative for anti-GM-CSF AAbs. This case will increase awareness and heighten suspicion of these infections in patients with the described presentations and clinical characteristics, and this will accelerate diagnosis and treatment.

Prospective Pilot Study of Cyclophosphamide as an Adjunct Treatment in Patients With Adult-Onset Immunodeficiency Associated With Anti-interferon-γ Autoantibodies

Background

Adult-onset immunodeficiency associated with interferon-γ autoantibody (IGA) is an emerging disease. The majority of patients require both antimicrobial and immunosuppressive treatments. However, anti-CD20 therapy is not fully accessible in a resource-limited setting to date.

Background

The objectives of this work were to study the efficacy of cyclophosphamide treatment and the role of laboratory biomarkers for disease progression monitoring.

Methods

A prospective pilot cohort study was conducted among patients with anti-interferon-γ autoantibodies (IGA) who had recurrent infections and required long-term antimicrobial therapy between 2015 and 2018. The patients were categorized into 2 groups: receipt of intravenous cyclophosphamide (IVCY) and receipt of anti-CD20 therapy (RTX). Clinical and laboratory data were determined.

Results

A total of 17 IGA patients were enrolled. Prolonged fever was the most common manifestation, and the most common infection identified was nontuberculous mycobacterial infections. Both were found in 88.24% of all patients.After completion of IVCY, 9/11 patients achieved complete remission and tended to reach remission faster compared with individuals in the RTX group. The median duration from treatment initiation to remission (interquartile range) was 84 (42-154) days in the IVCY group and 99 (51-202) days in the RTX group. In remission patients, the biomarkers of interest had normalized after treatment, except interferon γ autoantibody titers. There were no differences in adverse events among the 2 groups.

Conclusion

IVCY may be considered as alternative therapy in this population, especially in resource-limited countries. A comparable clinical outcome to RTX may support its use on a larger scale. However, further study is encouraged.

Clinical Significance of Interferon-γ Neutralizing Autoantibodies Against Disseminated Nontuberculous Mycobacterial Disease

Background

Interferon-γ neutralizing autoantibodies (nIFNγ-autoAbs) are reported in patients with disseminated nontuberculous mycobacteria (NTM) infection and may function by increasing the infection risk. Notwithstanding, the prevalence of nIFNγ-autoAbs as well as the clinical presentation, diagnosis, and natural history of disseminated NTM infection in these patients is poorly understood.

Methods

In this retrospective observational study, data and sera for 331 Japanese subjects with mycobacterial infection were collected and analyzed. IFNγ-autoAb titers in sera were quantified using an enzyme-linked immunosorbent assay; neutralizing capacity was evaluated via flow cytometry.

Results

Disseminated NTM was identified in 50 human immunodeficiency virus-uninfected patients. Of these, 30 of 37 (81%) immunocompetent patients had an increased nIFNγ-autoAb titer whereas only 1 of 13 (7.7%) immunodeficient patients had an increased nIFNγ-autoAb titer (P < .0001, χ2 test). Presenting symptoms were nonspecific and NTM infection was not included in the differential diagnosis in most cases. All patients with disseminated NTM and an increased serum nIFNγ-autoAb level received prolonged antimicrobial therapy. In 6 cases when antibiotic treatment was discontinued, NTM infection recurred and required resumption of antibiotic therapy for infection control. The mortality rate was 3.2% in disseminated NTM patients with nIFNγ-autoAbs and 21% in those without.

Conclusions

nIFNγ-autoAbs were present in most patients with disseminated NTM infection without a diagnosis of clinical immunodeficiency. Diagnosis of disseminated NTM requires a high degree of suspicion and can be improved by measuring serum nIFNγ-autoAb titer. Long-term antibiotic therapy helps prevent recrudescent NTM infection.

An updated review on phenocopies of primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) refer to a heterogenous group of disorders characterized clinically by increased susceptibility to infections, autoimmunity and increased risk of malignancies.

These group of disorders present with clinical manifestations similar to PIDs with known genetic defects but have either no genetic defect or have a somatic mutation and thus have been labelled as “Phenocopies of PIDs”. These diseases have been further subdivided into those associated with somatic mutations and those associated with presence of auto-antibodies against various cytokines.

In this review, we provide an update on clinical manifestations, diagnosis and management of these diseases.

Application of Flow Cytometry in the Diagnostics Pipeline of Primary Immunodeficiencies Underlying Disseminated Talaromyces marneffei Infection in HIV-Negative Children

Talaromyces (Penicillium) marneffei is an AIDS-defining infection in Southeast Asia and is associated with high mortality. It is rare in non-immunosuppressed individuals, especially children. Little is known about host immune response and genetic susceptibility to this endemic fungus. Genetic defects in the interferon-gamma (IFN-γ)/STAT1 signaling pathway, CD40/CD40 ligand- and IL12/IL12-receptor-mediated crosstalk between phagocytes and T-cells, and STAT3-mediated Th17 differentiation have been reported in HIV-negative children with talaromycosis and other endemic mycoses such as histoplasmosis, coccidioidomycosis, and paracoccidioidomycosis. There is a need to design a diagnostic algorithm to evaluate such patients. In this article, we review a cohort of pediatric patients with disseminated talaromycosis referred to the Asian Primary Immunodeficiency Network for genetic diagnosis of PID. Using these illustrative cases, we propose a diagnostics pipeline that begins with immunoglobulin pattern (IgG, IgA, IgM, and IgE) and enumeration of lymphocyte subpopulations (T-, B-, and NK-cells). The former could provide clues for hyper-IgM syndrome and hyper-IgE syndrome. Flow cytometric evaluation of CD40L expression should be performed for patients suspected to have X-linked hyper-IgM syndrome. Defects in interferon-mediated JAK-STAT signaling are evaluated by STAT1 phosphorylation studies by flow cytometry. STAT1 hyperphosphorylation in response to IFN-α or IFN-γ and delayed dephosphorylation is diagnostic for gain-of-function STAT1 disorder, while absent STAT1 phosphorylation in response to IFN-γ but normal response to IFN-α is suggestive of IFN-γ receptor deficiency. This simple and rapid diagnostic algorithm will be useful in guiding genetic studies for patients with disseminated talaromycosis requiring immunological investigations.

Hypercalcaemia secondary to disseminated Mycobacterium abscessus and Mycobacterium fortuitum

The incidence and prevalence of nontuberculous mycobacteria (NTM) infection is on the rise with many cases still going unreported. Given the vague and nonspecific clinical features of NTM infections, it is often missed or mistaken for Mycobacterium tuberculosis. The presumption that NTM infections are benign and do not contribute to morbidity no longer holds true. NTM infections need to be considered in patients with disseminated multisystem disease and in those not responding to standard M. tuberculosis treatment. As NTM infection is associated with granuloma formation, it can result in hypercalcaemia. Interestingly, there is evidence that there may be other mechanisms in play contributing to hypercalcaemia besides the increased calcitriol levels.

Neutralizing Activity of Anti-interferon-γ Autoantibodies in Adult-Onset Immunodeficiency Is Associated With Their Binding Domains

Adult-onset immunodeficiency (AOID) with anti-interferon-γ (IFN-γ) autoantibodies (autoAbs) is an emerging immunodeficiency syndrome in Asian countries. The presence of neutralizing anti-IFN-γ autoAbs are significantly associated with severe disseminated opportunistic infections. However, the characteristics of the neutralizing antibodies in patients are poorly defined. To better understand the properties of the anti-IFN-γ autoAbs in patients with opportunistic infections, a simplified competitive-binding ELISA was developed. The domains recognized by anti-IFN-γ autoAbs were assessed based on their competition with commercial neutralizing mouse anti-IFN-γ monoclonal antibodies (mAbs). First, the binding affinity and neutralizing capacity of these mAbs (clones B27, B133.5, and MD-1) were characterized. Kinetic analysis and epitope binning using bio-layer interferometry showed the comparable binding affinity of these mAbs to full-length IFN-γ and to the adjacent binding region. These mAbs did not recognize the synthetic 20-mer peptides and inhibited IFN-γ-mediated functions differently. In a competitive-binding ELISA, the anti-IFN-γ autoAbs in AOID serum blocked B27, B133.5, and MD-1 mAb binding. This evidence suggested that the autoAbs that competed with neutralizing mouse anti-IFN-γ mAbs recognized a discontinuous epitope of homodimeric IFN-γ as these mAbs. The patient autoAbs that recognized the B27 epitope exhibited strong neutralizing activity that was determined by the functional analysis. Our results demonstrated the heterogeneity of the autoAbs against IFN-γ in AOID patients and the different patterns among individuals. These data expand upon the fundamental knowledge of neutralizing anti-IFN-γ autoAbs in AOID patients.

Juvenile-Onset Immunodeficiency Secondary to Anti-Interferon-Gamma Autoantibodies

Immunodeficiency secondary to anti-interferon-gamma (anti-IFN-γ) autoantibodies was first described in 2004 as an acquired defect in the IFN-γ pathway leading to susceptibility to multiple opportunistic infections, including dimorphic fungi, parasites, and bacteria, especially tuberculosis and non-tuberculous mycobacterium (NTM) species. It has so far only been described in adult patients. We present 2 cases of disseminated NTM infections in otherwise immunocompetent children. A 16-year-old girl with Sweet's syndrome-like neutrophilic dermatosis developed recurrent fever and cervical lymphadenitis secondary to Mycobacterium abscessus. A 10-year-old boy with a history of prolonged fever, aseptic meningitis, aortitis, and arteritis in multiple blood vessels developed thoracic vertebral osteomyelitis secondary to Mycobacterium avium complex. Both patients were found to have positive serum neutralizing anti-IFNγ autoantibodies. Testing for anti-IFNγ autoantibodies should be considered in otherwise healthy immunocompetent hosts with recurrent or disseminated NTM infection. This represents a phenocopy of primary immunodeficiency which has been recently described only in adults. We report the first two cases of this phenomenon to affect children.

Blockade Effects of Anti-Interferon- (IFN-) γ Autoantibodies on IFN-γ-Regulated Antimicrobial Immunity

The interferon- (IFN-) γ expression is elicited in response to microbial infections and activates immune surveillance by antimicrobial immune elements to induce microbial killing. Patients with adult-onset immunodeficiency who suffer from recurrent infections with microbes, particularly nontuberculous mycobacteria (NTM), commonly display genetic defects in IFN-γ signaling as well as the generation of anti-IFN-γ autoantibodies (autoAbs). Because IFN-γ is an activator of macrophage differentiation and a proinflammatory activator of innate immunity, the blockade effects of the autoAbs present in NTM patient serum on IFN-γ are hypothesized to regulate the antimicrobial function of macrophages. In the presence of patient serum, IFN-γ-induced type 1 macrophage (M1) differentiation was inhibited in PMA-stimulated human monocytic THP-1 cells. Treatment with patient serum significantly blocked the production of proinflammatory factors, including cytokines/chemokines and reactive oxygen/nitrogen species, by M1 macrophages. Importantly, IFN-γ-facilitated phagocytosis and degradation of heat-killed mycobacterium were decreased by cotreatment with patient serum. These results show the blockade activity of anti-IFN-γ autoAbs on IFN-γ-mediated antimicrobial immunity in macrophages.

Clinical outcome and laboratory markers for predicting disease activity in patients with disseminated opportunistic infections associated with anti-interferon-γ autoantibodies

Background

Clinical courses and treatment outcomes are largely unknown in patients with adult-onset immunodeficiency associated with anti-interferon-gamma autoantibodies due to the fact that it was recently recognized and anti-IFN-γ auto-Abs detection is not widely available.

Methods and findings

Non-HIV-infected adult patients with detectable anti-IFN-γ auto-Abs diagnosed and followed at Siriraj Hospital, Bangkok, Thailand during January 2013 to November 2016 were prospectively studied. At each follow-up visit, patients were classified as stable or active disease according to symptoms and signs, and all proven OIs were recorded. Laboratory parameters, including erythrocyte sedimentation rate, C-reactive protein, and anti-IFN-γ auto-Abs level, were compared between active and stable disease episodes. We identified 80 patients with this clinical syndrome and followed them up during study period. Seventy-nine patients developed overall 194 proven opportunistic infections. Mycobacterium abscessus (34.5%) and Salmonella spp. (23.2%) were the two most common pathogens identified among these patients. Sixty-three patients were followed for a median of 2.7 years (range 0.6–4.8 years). Eleven (17.5%) patients achieved the drug-free remission period for at least 9 months. Four patients died. Anti-IFN-γ auto-Abs concentration was significantly lower at baseline and decreased over time in the drug-free remission group compared to another group (p = 0.001). C-reactive protein, erythrocyte sedimentation rate and white cell count were found to be useful biomarkers for determining disease activity during follow-up.

Conclusions

Reinfection or relapse of OIs is common despite long-term antimicrobial treatment in patients with anti-IFN-γ auto-Abs. Treatment to modify anti-IFN-γ auto-Abs production may improve long-term outcomes in this patient population.

Functional neutralization of anti-IFN-γ autoantibody in patients with nontuberculous mycobacteria infection

Interferon (IFN)-γ is crucial for normal immune surveillance and exhibits immunomodulatory, antimicrobial, and anticancer activity. Patients with nontuberculous mycobacteria (NTM) infection commonly express high levels of anti-IFN-γ autoantibodies (autoAbs) and suffer from recurrent infections due to adult-onset immunodeficiency with defects in IFN-γ immune surveillance. In this study, we developed the methods for determination of anti-IFN-γ autoAbs and then characterized their neutralizing activity in patients with NTM infection. A modified sandwich ELISA-based colorimetric assay followed by immunoblot analysis detected the presence of autoAbs in three out of five serum samples. Serum levels of IFN-γ were decreased. Synthetic peptide binding assay showed variable patterns of epitope recognition in patients positive for anti-IFN-γ autoAbs. Functional tests confirmed that patient serum blocked IFN-γ-activated STAT1 activation and IRF1 transactivation. Furthermore, IFN-γ-regulated inflammation, chemokine production and cytokine production were also blocked. These results provide potentially useful methods to assay anti-IFN-γ autoAbs and to characterize the effects of neutralizing autoAbs on IFN-γ signaling and bioactivity.

The molecular immunology of human susceptibility to fungal diseases: lessons from single gene defects of immunity

INTRODUCTION

Fungal diseases are a threat to human health. Therapies targeting the fungus continue to lead to disappointing results. Strategies targeting the host response represent unexplored opportunities for innovative treatments. To do so rationally requires the identification and neat delineation of critical mechanistic pathways that underpin human antifungal immunity. The study of humans with single-gene defects of the immune system, i.e. inborn errors of immunity (IEIs), provides a foundation for these paradigms. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses was performed to review the history of genetic resistance/susceptibility to fungi and identify IEIs associated with fungal diseases. Immunologic mechanisms from relevant IEIs were integrated with current definitions and understandings of mycoses to establish a framework to map out critical immunobiological pathways of human antifungal immunity. Expert opinion: Specific immune responses non-redundantly govern susceptibility to their corresponding mycoses. Defining these molecular pathways will guide the development of host-directed immunotherapies that precisely target distinct fungal diseases. These findings will pave the way for novel strategies in the treatment of these devastating infections.

Intravenous Cyclophosphamide Therapy for Anti-IFN-Gamma Autoantibody-Associated Mycobacterium abscessus Infection

Introduction

Anti-interferon-gamma (IFN-γ) autoantibodies are increasingly recognized as a cause of adult-onset immunodeficiency (AOID) worldwide. These patients are susceptible to various intracellular pathogens especially nontuberculous mycobacteria. Most of the patients have a refractory clinical course. Herein, we report the use of immunotherapy with pulse intravenous cyclophosphamide (IVCY) in patients who had progressive, refractory Mycobacterium abscessus infection.

Method

We included patients, seen at Srinagarind Hospital, Thailand, infected with M. abscessus, who had received ≥3 courses of parenteral antibiotics within the last 12 months and who received pulse IVCY with a tapering dose of prednisolone.

Results

There were 8 AOID patients who met the criteria and received pulse IVCY between January 2011 and December 2015. One patient was lost to follow-up after 5 courses of IVCY: he had died at home 3 months later. Five patients had favorable outcomes: 2 were able to discontinue NTM therapy, and 3 had stable disease and were on NTM treatment without hospitalization for parenteral antibiotics. Two patients relapsed and needed hospitalization. The IFN-γ Ab titers among the 7 patients were significantly decreased during treatment, and the median initial antibody titer started at 200,000 and then decreased to 5,000 after 2 years of treatment (P < 0.0001). The antibody titer reduction among responsive vs. nonresponsive patient was significantly different after 6 months of treatment: the median antibody titer was 5,000 and 100,000, respectively (P = 0.0467).

Conclusion

IVCY therapy might be an alternative treatment for AOID patients infected with M. abscessus and refractory to antimycobacterial therapy.

Epidemiology of and risk factors for extrapulmonary nontuberculous mycobacterial infections in Northeast Thailand

Background

Nontuberculous mycobacterial (NTM) infection is increasing worldwide. Current epidemiological data and knowledge of risk factors for this disease are limited. We investigated the trends in and risk of NTM infection in Northeast Thailand during 2012–2016.

Methods

Patient demographics, infection site(s), and underlying disease or conditions from 530 suspected cases of NTM infections were retrieved from medical records, reviewed and analyzed. A diagnosis of true NTM infection was accepted in 150 cases. Risk factor analyses were done for extrapulmonary NTM infections compared to pulmonary NTM infections and for Mycobacterium abscessus compared to members of the Mycobacterium avium complex (MAC). Trend analysis among NTM species causing NTM infections was performed.

Results

The most common species of NTMs causing extrapulmonary (n = 114) and pulmonary (n = 36) NTM infections in Northeast Thailand were M. abscessus (25.4% of extrapulmonary infected cases and 27.8% of pulmonary cases) followed by MAC (14.9% of extrapulmonary and 13.9% of pulmonary cases). Presence of anti-IFN-γ autoantibodies was the major risk factor for extrapulmonary (odds ratio (OR) = 20.75, 95%CI [2.70–159.24]) compared to pulmonary NTM infection. M. abscessus infection was less likely (OR = 0.17; 95%CI [0.04–0.80]) to be found in patients with HIV infection than was MAC infection. The prevalence of NTM infection, especially M. abscessus, in Northeast Thailand has recently increased. Extrapulmonary NTM and complicated NTM infections have increased in concordance with the recent trend of increasing frequency of anti-IFN-γ autoantibodies in the population.

Conclusions

M. abscessus was the commonest NTM pathogen followed by MAC. The prevalence of NTM infections and anti-IFN-γ are showing an upward trend. Autoimmune disease due to anti-IFN-γ is the major risk factor for extrapulmonary NTM infection in Northeast Thailand.

Repurposing QuantiFERON for Detection of Neutralizing Interferon-γ Autoantibodies in Patients With Nontuberculous Mycobacterial Infections

Nontuberculous mycobacterial infections due to autoantibodies targeting interferon-γ are an emerging medical problem. However, case finding is hampered due to highly complex diagnostic procedures not available in routine laboratories. We show that QuantiFERON assays can be exploited as a simple screening tool that may facilitate adequate and timely treatment.

Dot enzyme-linked immunosorbent assay strip as a screening tool for detection of autoantibody to interferon gamma in sera of suspected cases of adult-onset immunodeficiency

BACKGROUND

Being able to detect the presence of autoantibodies to interferon (IFN)-γ in serum is essential for evaluating patients with suspected adult-onset immunodeficiency (AOID) with unusual intracellular infections. Most reported patients with AOID have been Asian, although the exact prevalence of this illness is unknown. To date, no standard assay exists to detect autoantibodies to IFN-γ. An easy-to-use, low-cost assay that can be performed in any laboratory would be a valuable tool for clinical management of AOID, as well as better reveal its prevalence.

METHODS

Our experimental study exploited a dot enzyme-linked immunosorbent assay (Dot-ELISA) strip to detect autoantibodies to IFN-γ. Sera from 66 HIV-negative patients having autoantibodies to IFN-γ as determined by indirect ELISA were tested.

RESULTS

Dot enzyme-linked immunosorbent assay was sensitive (100%) and specific (94.5%), with a positive predictive value of 97.6% and a negative predictive value of 100%.

CONCLUSION

This simple method provides prompt qualitative results that can be read visually and used in facilities with limited testing capabilities.

Characterization of anti-interferon-γ antibodies in HIV-negative immunodeficient patients infected with unusual intracellular microorganisms

A major characteristic of immunodeficiency associated with life-threatening intracellular infection in adults is the presence of anti-interferon-γ antibodies. Although little is known about the mechanism underlying this syndrome, it is believed that the antibodies inhibit the activity of downstream signaling pathway of interferon-γ. In this study, the characteristics of these antibodies in patients who presented, or have a history of, intracellular infection and were positive to anti-interferon-γ antibodies were investigated. The antibodies exhibited mainly the IgG1 and the IgG4 subtypes and recognized the C-terminal of the interferon-γ linear epitope containing the KRKR motif, which is required for the biological activity of interferon-γ. The antibodies bound to recombinant interferon-γ with significantly lower avidity than antibodies to a recall antigen, tetanus toxoid, suggesting that the antibodies might have not undergone affinity maturation. The data from this study may provide fundamental information to better understand the properties of anti-interferon-γ antibodies, which can be useful for future studies. Impact statement An increase in the number of immunodeficient patients related to autoantibodies to interferon (IFN)-γ has been observed particularly in East Asian adults. These patients are often presented with opportunistic infections caused by intracellular pathogens, including non-tuberculous mycobacteria (NTM), Cryptococcus neoformans, Penicillium marneffei (now called Talaromyces marneffei), and non-typhoidal Salmonella spp. The mortality rate for this syndrome is relatively high with 32% patients dying at the median time of 25 months after diagnosis. Characterization of these autoantibodies may promote better understanding of the syndrome, an emerging health problem affecting East Asia populations and impeding their welfare and economic development.

A 38-year-old woman with necrotising cervical lymphadenitis due to Histoplasma capsulatum

Case presentation

We analysed a 38-year-old woman with disseminated histoplasmosis for primary immunodeficiency. Her blood showed no IFN-γ response while her peripheral blood mononuclear cells (PBMCs) did. We identified IFN-γ autoantibodies of the IgG class in her serum.

Conclusion

IFN-γ autoantibodies leading to infections were so far mainly detected in people from Asian descent, where it was found to be associated with certain HLA types. This may be the first patient of African descent, and without the typical HLA types that predispose to this problem, that produces IFN-γ autoantibodies.

Use of QuantiFERON-TB Gold In-tube assay in screening for neutralizing anti-interferon-γ autoantibodies in patients with disseminated nontuberculous mycobacterial infection

OBJECTIVE

Anti-interferon- γ (IFN-γ) autoantibodies (anti-IFN-γ Abs) have been increasingly recognized as an important cause of disseminated nontuberculous mycobacterial (DNTM) infection, and identification of this immunodeficiency impacts clinical management. However, the protean disease manifestations and inaccessibility to diagnostic tests in clinical settings hamper its early diagnosis. Here, we sought to determine whether QuantiFERON-TB Gold In-tube (QFT-GIT), a commercialized IFN-γ release assay, could be used to screen for neutralizing anti-IFN-γ Abs among previously healthy adults with DNTM infection.

METHODS

Non-HIV patients with DNTM infection were prospectively enrolled for the QFT-GIT assays. We measured their plasma concentration of anti-IFN-γ Abs and their neutralizing capacity through enzyme-linked immunosorbent assay and flow cytometry. We then analysed the correlation between QFT-GIT results and the presence of neutralizing anti-IFN-γ Abs among patients with and without previously recognized immunosuppression, respectively.

RESULTS

Irrespective of the autoantibody concentration or disease activity, all patients with neutralizing anti-IFN-γ Abs (100%, 30/30) had indeterminate QFT-GIT results because of extremely low or undetectable IFN-γ levels in the mitogen tubes. None of the four DNTM patients who were previously healthy and tested negative of anti-IFN-γ Abs had an indeterminate QFT-GIT result, and their IFN-γ levels in the mitogen tube were significantly higher than those of the patients with anti-IFN-γ Abs (8.28 IU/mL vs. 0.05 IU/mL, p 0.001).

CONCLUSION

An indeterminate QFT-GIT result because of undetectable or extremely low IFN-γ level in the mitogen tube suggests the presence of neutralizing anti-IFN-γ Abs in a previously healthy patient with DNTM infection.

Cellular and Molecular Defects Underlying Invasive Fungal Infections-Revelations from Endemic Mycoses

The global burden of fungal diseases has been increasing, as a result of the expanding number of susceptible individuals including people living with human immunodeficiency virus (HIV), hematopoietic stem cell or organ transplant recipients, patients with malignancies or immunological conditions receiving immunosuppressive treatment, premature neonates, and the elderly. Opportunistic fungal pathogens such as Aspergillus, Candida, Cryptococcus, Rhizopus, and Pneumocystis jiroveci are distributed worldwide and constitute the majority of invasive fungal infections (IFIs). Dimorphic fungi such as Histoplasma capsulatum, Coccidioides spp., Paracoccidioides spp., Blastomyces dermatiditis, Sporothrix schenckii, Talaromyces (Penicillium) marneffei, and Emmonsia spp. are geographically restricted to their respective habitats and cause endemic mycoses. Disseminated histoplasmosis, coccidioidomycosis, and T. marneffei infection are recognized as acquired immunodeficiency syndrome (AIDS)-defining conditions, while the rest also cause high rate of morbidities and mortalities in patients with HIV infection and other immunocompromised conditions. In the past decade, a growing number of monogenic immunodeficiency disorders causing increased susceptibility to fungal infections have been discovered. In particular, defects of the IL-12/IFN-γ pathway and T-helper 17-mediated response are associated with increased susceptibility to endemic mycoses. In this review, we put together the various forms of endemic mycoses on the map and take a journey around the world to examine how cellular and molecular defects of the immune system predispose to invasive endemic fungal infections, including primary immunodeficiencies, individuals with autoantibodies against interferon-γ, and those receiving biologic response modifiers. Though rare, these conditions provide importance insights to host defense mechanisms against endemic fungi, which can only be appreciated in unique climatic and geographical regions.