Viral infections in interferon-gamma receptor deficiency

A robust mouse model of HPIV-3 infection and efficacy of GS-441524 against virus-induced lung pathology

Human parainfluenza virus type 3 (HPIV-3) can cause severe respiratory tract infections. There are no convenient small-animal infection models. Here, we show viral replication in the upper and lower airways of AG129 mice (double IFNα/β and IFNγ receptor knockout mice) upon intranasal inoculation. By multiplex fluorescence RNAscope and immunohistochemistry followed by confocal microscopy, we demonstrate viral tropism to ciliated cells and club cells of the bronchiolar epithelium. HPIV-3 causes a marked lung pathology. No virus transmission of the virus was observed by cohousing HPIV-3-infected AG129 mice with other mice. Oral treatment with GS-441524, the parent nucleoside of remdesivir, reduced infectious virus titers in the lung, with a relatively normal histology. Intranasal treatment also affords an antiviral effect. Thus, AG129 mice serve as a robust preclinical model for developing therapeutic and prophylactic strategies against HPIV-3. We suggest further investigation of GS-441524 and its prodrug forms to treat HPIV-3 infection in humans.

Deucravacitinib in moderate-to-severe plaque psoriasis: Pooled safety and tolerability over 52 weeks from two phase 3 trials (POETYK PSO-1 and PSO-2)

BACKGROUND

Two phase 3 trials, POETYK PSO-1 and PSO-2, previously established the efficacy and overall safety of deucravacitinib, an oral, selective, allosteric tyrosine kinase 2 (TYK2) inhibitor, in plaque psoriasis.

OBJECTIVES

To further assess the safety of deucravacitinib over 52 weeks in the pooled population from these two trials.

METHODS

Pooled safety data were evaluated from PSO-1 and PSO-2 in which patients with moderate-to-severe plaque psoriasis were randomized 1:2:1 to receive oral placebo, deucravacitinib or apremilast.

RESULTS

A total of 1683 patients were included in the pooled analysis. Adverse event (AE) incidence rates were similar in each treatment group, serious AEs were low and balanced across groups, and discontinuation rates were lower with deucravacitinib versus placebo or apremilast. No new safety signals emerged with longer deucravacitinib treatment. Exposure-adjusted incidence rates of AEs of interest with placebo, deucravacitinib and apremilast, respectively, were as follows: serious infections (0.8/100 person-years [PY], 1.7/100 PY, and 1.8/100 PY), major adverse cardiovascular events (1.2/100 PY, 0.3/100 PY, and 0.9/100 PY), venous thromboembolic events (0, 0.2/100 PY, and 0), malignancies (0, 1.0/100 PY and 0.9/100 PY), herpes zoster (0.4/100 PY, 0.8/100 PY, and 0), acne (0.4/100 PY, 2.9/100 PY, and 0) and folliculitis (0, 2.8/100 PY, and 0.9/100 PY). No clinically meaningful changes from baseline in mean levels, or shifts from baseline to CTCAE grade ≥3 abnormalities, were reported in laboratory parameters with deucravacitinib.

CONCLUSIONS

Deucravacitinib was well-tolerated with acceptable safety over 52 weeks in patients with psoriasis.

Anti-Interferon-γ Therapy for Cytokine Storm Syndromes

A vast body of evidence provides support to a central role of exaggerated production of interferon-γ (IFN-γ) in causing hypercytokinemia and signs and symptoms of hemophagocytic lymphohistiocytosis (HLH). In this chapter, we will describe briefly the roles of IFN-γ in innate and adaptive immunity and in host defense, summarize results from animal models of primary HLH and secondary HLH with particular emphasis on targeted therapeutic approaches, review data on biomarkers associated with activation of the IFN-γ pathway, and discuss initial efficacy and safety results of IFN-γ neutralization in humans.

Bacterial-induced or passively administered interferon gamma conditions the lung for early control of SARS-CoV-2

Type-1 and type-3 interferons (IFNs) are important for control of viral replication; however, less is known about the role of Type-2 IFN (IFNγ) in anti-viral immunity. We previously observed that lung infection with Mycobacterium bovis BCG achieved though intravenous (iv) administration provides strong protection against SARS-CoV-2 in mice yet drives low levels of type-1 IFNs but robust IFNγ. Here we examine the role of ongoing IFNγ responses to pre-established bacterial infection on SARS-CoV-2 disease outcomes in two murine models. We report that IFNγ is required for iv BCG induced reduction in pulmonary viral loads, an outcome dependent on IFNγ receptor expression by non-hematopoietic cells. Importantly, we show that BCG infection prompts pulmonary epithelial cells to upregulate IFN-stimulated genes with reported anti-viral activity in an IFNγ-dependent manner, suggesting a possible mechanism for the observed protection. Finally, we confirm the anti-viral properties of IFNγ by demonstrating that the recombinant cytokine itself provides strong protection against SARS-CoV-2 challenge when administered intranasally. Together, our data show that a pre-established IFNγ response within the lung is protective against SARS-CoV-2 infection, suggesting that concurrent or recent infections that drive IFNγ may limit the pathogenesis of SARS-CoV-2 and supporting possible prophylactic uses of IFNγ in COVID-19 management.

IFN-γ lowers tumor growth by increasing glycolysis and lactate production in a nitric oxide-dependent manner: implications for cancer immunotherapy

Introduction

Interferon-gamma (IFN-γ), the sole member of the type-II interferon family, is well known to protect the host from infectious diseases as well as mount anti-tumor responses. The amounts of IFN-γ in the tumor microenvironment determine the host responses against tumors; however, several tumors employ evasive strategies by responding to low IFN-γ signaling.

Methods

In this study, the response of various tumor cell lines to IFN-γ was studied in vitro.

Results

IFN-γ-activation increases glycolytic flux and reduces mitochondrial function in a nitric oxide (NO)- and reactive oxygen species (ROS)-dependent manner in the H6 hepatoma tumor cell line. The higher glycolysis further fueled NO and ROS production, indicating a reciprocal regulation. These processes are accompanied by Hypoxia inducing factor (HIF)-1α stabilization and HIF-1α-dependent augmentation of the glycolytic flux. The IFN-γ enhancement of lactate production also occurred in other NO-producing cell lines: RAW 264.7 monocyte/macrophage and Renca renal adenocarcinoma. However, two other tumor cell lines, CT26 colon carcinoma and B16F10 melanoma, did not produce NO and lactate upon IFN-γ-activation. HIF-1α stabilization upon IFN-γ-activation led to lower cell growth of B16F10 but not CT26 cells. Importantly, the IFN-γ-activation of both CT26 and B16F10 cells demonstrated significant cellular growth reduction upon metabolic rewiring by exogenous administration of potassium lactate.

Discussion

Clinical studies have shown the crucial roles of IFN-γ for successful cancer immunotherapies involving checkpoint inhibitors and chimeric antigen receptor T cells. The positive implications of this study on the metabolic modulation of IFN-γ activation on heterogeneous tumor cells are discussed.

Interferons-Implications in the Immune Response to Respiratory Viruses

Interferons (IFN) are an assemblage of signaling proteins made and released by various host cells in response to stimuli, including viruses. Respiratory syncytial virus (RSV), influenza virus, and SARS-CoV-2 are major causes of respiratory disease that induce or antagonize IFN responses depending on various factors. In this review, the role and function of type I, II, and III IFN responses to respiratory virus infections are considered. In addition, the role of the viral proteins in modifying anti-viral immunity is noted, as are the specific IFN responses that underly the correlates of immunity and protection from disease.

Systemic aspergillosis in a patient with interferon gamma receptor 1 deficiency; a case report

BACKGROUND

Interferon-gamma receptor deficiency is a heterogeneous spectrum of disease which involves mutations in IFNGR1, IFNGR2 genes, and the downstream signaling proteins such as STAT1. These mutations are associated with immunodeficiency 27 A and 27B, making the patient prone to mycobacterial infections. Patients with this condition are also at increased risk for affliction with viral and bacterial infections, such as with the Herpesviridae family, Listeria, and Salmonella. Moreover, SH2B3 mutation is associated with autoimmune and lymphoproliferative conditions.

CASE PRESENTATION

the patient was a 19-month-old infant girl who presented with a two-week history of fever. She had near-normal flowcytometry with high IgM and IgE. She had pneumonic infiltration in her chest and right hilar and para-aortic lymphadenopathy. PCR of whole blood for Aspergillus fumigatus came back positive. In her Whole Exome Sequencing she had IFNGR1 and SH2B3 mutations.

CONCLUSION

systemic fungal infections such as Aspergillosis can occur in patients with interferon-gamma receptor one deficiency. This type of immunodeficiency should be considered in treating patients with systemic Aspergillosis.

Mendelian susceptibility to mycobacterial disease: an overview

Background

Mycobacteria include ubiquitous species of varying virulence. However, environmental and individual-specific factors, particularly host genetics, play a crucial role in the outcome of exposure to mycobacteria. The first molecular evidence of a monogenic predisposition to mycobacteria came from the study of Mendelian susceptibility to mycobacterial disease (MSMD), a rare inborn error of IFN-γ immunity conferring a selective susceptibility to infections even with low virulent mycobacteria, in patients, mostly children, without recognizable immune defects in routine tests. This article provides a global and updated description of the most important molecular, cellular, and clinical features of all known monogenic defects of MSMD.

Results

Over the last 20 years, 19 genes were found to be mutated in MSMD patients (IFNGR1, IFNGR2, IFNG, IL12RB1, IL12RB2, IL23R, IL12B, ISG15, USP18, ZNFX1, TBX21, STAT1, TYK2, IRF8, CYBB, JAK1, RORC, NEMO, and SPPL2A), and the allelic heterogeneity at these loci has led to the definition of 35 different genetic defects. Despite the clinical and genetic heterogeneity, almost all genetic etiologies of MSMD alter the interferon gamma (IFN-γ)-mediated immunity, by impairing or abolishing IFN-γ production or the response to this cytokine or both. It was proven that the human IFN-γ level is a quantitative trait that defines the outcome of mycobacterial infection.

Conclusion

The study of these monogenic defects contributes to understanding the molecular mechanism of mycobacterial infections in humans and to the development of new diagnostic and therapeutic approaches to improve care and prognosis. These discoveries also bridge the gap between the simple Mendelian inheritance and complex human genetics.

Azathioprine therapy induces selective NK cell depletion and IFN-γ deficiency predisposing to herpesvirus reactivation

BACKGROUND

Azathioprine is a widely prescribed drug for patients with chronic inflammatory diseases such as myasthenia gravis or organ transplant recipients. Azathioprine exerts immunosuppressive effects by inhibiting intracellular purine synthesis and reducing the numbers of circulating B and T lymphocytes. Case reports indicate increased risk for serious infections that can occur despite regular measurements of lymphocyte counts during azathioprine therapy.

OBJECTIVE

We sought to comprehensively investigate therapy-associated patient risks and the underlying immune dysfunction of azathioprine use.

METHODS

Peripheral blood leukocytes were analyzed using single-cell mass and spectral flow cytometry to detect specific effects of azathioprine use on the systemic immune signature. Therapy-associated clinical features were analyzed in 2 independent cohorts of myasthenia gravis patients.

RESULTS

Azathioprine therapy selectively induced pronounced CD56^dimCD16⁺ natural killer cell depletion and concomitant IFN-γ deficiency. Cytokine profiling revealed a specific contraction of classical T_H1 cells during azathioprine treatment. We further observed an increased occurrence of reactivation of endogenous latent herpesviruses in the azathioprine-treated group versus in patients with myasthenia gravis who were not receiving immunomodulatory treatment; this increased occurrence was validated in an independent cohort.

CONCLUSION

Our study highlights the risk of development of adverse events during azathioprine therapy and suggests that natural killer cell monitoring could be valuable in clinical practice.

Immunity to Cryptosporidium: Lessons from Acquired and Primary Immunodeficiencies

Cryptosporidium is a ubiquitous protozoan parasite that infects gut epithelial cells and causes self-limited diarrhea in immunocompetent individuals. However, in immunocompromised hosts with global defects in T cell function, this infection can result in chronic, life-threatening disease. In addition, there is a subset of individuals with primary immunodeficiencies associated with increased risk for life-threatening cryptosporidiosis. These patients highlight MHC class II expression, CD40-CD40L interactions, NF-κB signaling, and IL-21 as key host factors required for resistance to this enteric pathogen. Understanding which immune deficiencies do (or do not) lead to increased risk for severe Cryptosporidium may reveal mechanisms of parasite restriction and aid in the identification of novel strategies to manage this common pathogen in immunocompetent and deficient hosts.

The lung in inborn errors of immunity: From clinical disease patterns to molecular pathogenesis

In addition to being a vital organ for gas exchange, the lung is a crucial immune organ continuously exposed to the external environment. Genetic defects that impair immune function, called inborn errors of immunity (IEI), often have lung disease as the initial and/or primary manifestation. Common types of lung disease seen in IEI include infectious complications and a diverse group of diffuse interstitial lung diseases. Although lung damage in IEI has been historically ascribed to recurrent infections, contributions from potentially targetable autoimmune and inflammatory pathways are now increasingly recognized. This article provides a practical guide to identifying the diverse pulmonary disease patterns in IEI based on lung imaging and respiratory manifestations, and integrates this clinical information with molecular mechanisms of disease and diagnostic assessments in IEI. We cover the entire IEI spectrum, including immunodeficiencies and immune dysregulation with monogenic autoimmunity and autoinflammation, as well as recently described IEI with pulmonary manifestations. Although the pulmonary manifestations of IEI are highly relevant for all age groups, special emphasis is placed on the pediatric population, because initial presentations often occur during childhood. We also highlight the pivotal role of genetic testing in the diagnosis of IEI involving the lungs and the critical need to develop multidisciplinary teams for the challenging evaluation of these rare but potentially life-threatening disorders.

Transcriptional response to VZV infection is modulated by RNA polymerase III in lung epithelial cell lines

Ancestral RNA polymerase III (Pol III) is a multi-subunit polymerase responsible for transcription of short non-coding RNA, such as double-stranded short interspersed nuclear elements (SINEs). Although SINE ncRNAs are generally transcriptionally repressed, they can be induced in response to viral infections and can stimulate immune signaling pathways. Indeed, mutations in RNA Pol III have been associated with poor antiviral interferon response following infection with varicella zoster virus (VZV). In this study, we probed the role of Pol III transcripts in the detection and initial immune response to VZV by characterizing the transcriptional response following VZV infection of wild type A549 lung epithelial cells as well as A549 cells lacking specific RNA sensors MAVS and TLR3, or interferon-stimulated genes RNase L and PKR in presence or absence of functional RNA Pol III. Multiple components of the antiviral sensing and interferon signaling pathways were involved in restricting VZV replication in lung epithelial cells thus suggesting an innate defense system with built-in redundancy. In addition, RNA Pol III silencing altered the antiviral transcriptional program indicating that it plays an essential role in the sensing of VZV infection.

Cytomegalovirus in primary immunodeficiency

PURPOSE OF REVIEW

Cytomegalovirus (CMV) infection and disease are well described in the setting of secondary immunodeficiency. Less is known about CMV in the context of primary immunodeficiencies (PIDs), where inborn errors in one or more arms of the immune system result in variable degrees of CMV susceptibility.

RECENT FINDINGS

PID presents unique challenges in the diagnosis and management of CMV disease. The clinical presentation of CMV in PID is often severe, accelerated by underlying immune dysregulation and iatrogenic immunosuppression. Here we describe the clinical significance of CMV infection in PID, the key components of immune defence against CMV and how these are affected in specific PIDs. CMV disease is under-recognized as a complication of common variable immunodeficiency (CVID). High rates of CMV end-organ disease, mortality, development of CMV resistance and prolonged antiviral use have been observed in individuals with CVID.

SUMMARY

We recommend that clinicians tailor their approach to the individual based on their underlying immune deficit and maintain a high index of suspicion and low threshold for treatment. More research is required to improve stratification of CMV risk in PID, develop new diagnostic tools and manage end-organ disease in this cohort.

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.

Enhanced osteoclastogenesis in patients with MSMD due to impaired response to IFN-γ

BACKGROUND

Patients with Mendelian susceptibility to mycobacterial disease (MSMD) experience recurrent and/or persistent infectious diseases associated with poorly virulent mycobacteria. Multifocal osteomyelitis is among the representative manifestations of MSMD. The frequency of multifocal osteomyelitis is especially high in patients with MSMD etiologies that impair cellular response to IFN-γ, such as IFN-γR1, IFN-γR2, or STAT1 deficiency.

OBJECTIVES

This study sought to characterize the mechanism underlying multifocal osteomyelitis in MSMD.

METHODS

GM colonies prepared from bone marrow mononuclear cells from patients with autosomal dominant (AD) IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 gain of function (GOF) and from healthy controls were differentiated into osteoclasts in the presence or absence of IFN-γ. The inhibitory effect of IFN-γ on osteoclastogenesis was investigated by quantitative PCR, immunoblotting, tartrate-resistant acid phosphatase staining, and pit formation assays.

RESULTS

Increased osteoclast numbers were identified by examining the histopathology of osteomyelitis in patients with AD IFN-γR1 deficiency or AD STAT1 deficiency. In the presence of receptor activator of nuclear factor kappa-B ligand and M-CSF, GM colonies from patients with AD IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 GOF differentiated into osteoclasts, similar to GM colonies from healthy volunteers. IFN-γ concentration-dependent inhibition of osteoclast formation was impaired in GM colonies from patients with AD IFN-γR1 deficiency or AD STAT1 deficiency, whereas it was enhanced in GM colonies from patients with STAT1 GOF.

CONCLUSIONS

Osteoclast differentiation is increased in AD IFN-γR1 deficiency and AD STAT1 deficiency due to an impaired response to IFN-γ, leading to excessive osteoclast proliferation and, by inference, increased bone resorption in infected foci, which may underlie multifocal osteomyelitis.

Clinical and Molecular Findings in Mendelian Susceptibility to Mycobacterial Diseases: Experience From India

Mendelian Susceptibility to Mycobacterial diseases (MSMD) are a group of innate immune defects with more than 17 genes and 32 clinical phenotypes identified. Defects in the IFN-γ mediated immunity lead to an increased susceptibility to intracellular pathogens like mycobacteria including attenuated Mycobacterium bovis-Bacillus Calmette-Guérin (BCG) vaccine strains and non-tuberculous environmental mycobacteria (NTM), Salmonella, fungi, parasites like Leishmania and some viruses, in otherwise healthy individuals. Mutations in the IL12RB1 gene are the commonest genetic defects identified. This retrospective study reports the clinical, immunological, and molecular characteristics of a cohort of 55 MSMD patients from 10 centers across India. Mycobacterial infection was confirmed by GeneXpert, Histopathology, and acid fast bacilli staining. Immunological workup included lymphocyte subset analysis, Nitro blue tetrazolium (NBT) test, immunoglobulin levels, and flow-cytometric evaluation of the IFN-γ mediated immunity. Genetic analysis was done by next generation sequencing (NGS). Disseminated BCG-osis was the commonest presenting manifestation (82%) with a median age of presentation of 6 months due to the practice of BCG vaccination at birth. This was followed by infection with Salmonella and non-typhi Salmonella (13%), Cytomegalovirus (CMV) (11%), Candida (7%), NTM (4%), and Histoplasma (2%). Thirty-six percent of patients in cohort were infected by more than one organism. This study is the largest cohort of MSMD patients reported from India to the best of our knowledge and we highlight the importance of work up for IL-12/IL-23/ISG15/IFN-γ circuit in all patients with BCG-osis and suspected MSMD irrespective of age.

Genetic influences on viral-induced cytokine responses in the lung

Infection with respiratory viruses such as influenza, respiratory syncytial virus and coronavirus provides a difficult immunological challenge for the host, where a balance must be established between controlling viral replication and limiting damage to the delicate lung structure. Although the genetic architecture of host responses to respiratory viral infections is not yet understood, it is clear there is underlying heritability that influences pathogenesis. Immune control of virus replication is essential in respiratory infections, but overt activation can enhance inflammation and disease severity. Cytokines initiate antiviral immune responses but are implicated in viral pathogenesis. Here, we discuss how host genetic variation may influence cytokine responses to respiratory viral infections and, based on our current understanding of the role that cytokines play in viral pathogenesis, how this may influence disease severity. We also discuss how induced pluripotent stem cells may be utilised to probe the mechanistic implications of allelic variation in genes in virus-induced inflammatory responses. Ultimately, this could help to design better immune modulators, stratify high risk patients and tailor anti-inflammatory treatments, potentially expanding the ability to treat respiratory virus outbreaks in the future.

Genetic Lesions of Type I Interferon Signalling in Human Antiviral Immunity

The concept that type I interferons (IFN-I) are essential to antiviral immunity derives from studies on animal models and cell lines. Virtually all pathogenic viruses have evolved countermeasures to IFN-I restriction, and genetic loss of viral IFN-I antagonists leads to virus attenuation. But just how important is IFN-I to antiviral defence in humans? The recent discovery of genetic defects of IFN-I signalling illuminates this and other questions of IFN biology, including the role of the mucosa-restricted type III IFNs (IFN-III), informing our understanding of the place of the IFN system within the concerted antiviral response. Here we review monogenic lesions of IFN-I signalling pathways and summarise the organising principles which emerge.

A case of recurrent herpes simplex 2 encephalitis, VZV reactivations, and dominant partial interferon-gamma-receptor-1 deficiency supports relevance of IFNgamma for antiviral defense in humans

Background

Unlike infections with mycobacteria, reports of unusual viral infections in interferon-gamma-receptor (IFNγR) deficient patients are scarce. Therefore, discussion about increased susceptibility to viral infections in these patients is ongoing.

Case presentation

We describe a 51-year-old male with dominant partial interferon-gamma-receptor-1 (IFNγR1)-deficiency and recurrent Herpes simplex 2 meningoencephalitis as well as other viral reactivations since childhood.

Conclusions

This case further confirms an enhanced risk for viral disease in IFNγR-deficient patients and a role of interferon gamma for human antiviral defense.

Bacillus Calmette-Guérin (BCG)-associated hemophagocytic lymphohistiocytosis in the setting of IFN-γR1 deficiency: A diagnostic dilemma

Hemophagocytic lymphohistiocytosis (HLH) disease is a severe immune dysregulation caused by mutations in genes required for lymphocyte cytotoxicity function. However, HLH-like syndrome may develop secondary to infections, malignancy, and autoimmunity. Primary immunodeficiencies (PIDs) could predispose to HLH syndrome after uncontrolled infections. Mendelian susceptibility to mycobacterial disease (MSMD) is a PID characterized by a predisposition to clinical disease caused by weakly virulent mycobacteria, such as bacillus Calmette-Guérin (BCG). Inborn errors of interferon-γ immunity caused by mutations in 16 genes, underly MSMD development. Here, we report a case of fatal interferon-γ receptor 1 deficiency with disseminated BCG infection, which was initially diagnosed with HLH disease. We also include a review of cases reported in the literature.

Human inborn errors of immunity to herpes viruses

Infections with any of the nine human herpes viruses (HHV) can be asymptomatic or life-threatening. The study of patients with severe diseases caused by HHVs, in the absence of overt acquired immunodeficiency, has led to the discovery or diagnosis of various inborn errors of immunity. The related inborn errors of adaptive immunity disrupt α/β T-cell rather than B-cell immunity. Affected patients typically develop HHV infections in the context of other infectious diseases. However, this is not always the case, as illustrated by inborn errors of SAP-dependent T-cell immunity to EBV-infected B cells. The related inborn errors of innate immunity disrupt leukocytes other than T and B cells, non-hematopoietic cells, or both. Patients typically develop only a single type of infection due to HHV, although, again, this is not always the case, as illustrated by inborn errors of TLR3 immunity resulting in HSV1 encephalitis in some patients and influenza pneumonitis in others. Most severe HHV infections in otherwise healthy patients remains unexplained. The forward human genetic dissection of isolated and syndromic HHV-driven illnesses will establish the molecular and cellular basis of protective immunity to HHVs, paving the way for novel diagnosis and management strategies.

Primary Immunodeficiency Diseases and Bacillus Calmette-Guérin (BCG)-Vaccine-Derived Complications: A Systematic Review

BACKGROUND

Bacillus Calmette-Guérin (BCG) vaccine is a live attenuated bacterial vaccine derived from Mycobacterium bovis, which is mostly administered to neonates in regions where tuberculosis is endemic. Adverse reactions after BCG vaccination are rare; however, immunocompromised individuals and in particular patients with primary immunodeficiencies (PIDs) are prone to develop vaccine-derived complications.

OBJECTIVE

To systematically review demographic, clinical, immunologic, and genetic data of PIDs that present with BCG vaccine complications. Moreover, we performed a meta-analysis aiming to determine the BCG-vaccine complications rate for patients with PID.

METHODS

We conducted electronic searches on Embase, Web of Science, PubMed, and Scopus (1966 to September 2018) introducing terms related to PIDs, BCG vaccination, and BCG vaccine complications. Studies with human subjects with confirmed PID, BCG vaccination history, and vaccine-associated complications (VACs) were included.

RESULTS

A total of 46 PIDs associated with BCG-VAC were identified. Severe combined immunodeficiency was the most common (466 cases) and also showed the highest BCG-related mortality. Most BCG infection cases in patients with PID were reported from Iran (n = 219 [18.8%]). The overall frequency of BCG-VAC in the included 1691 PID cases was 41.5% (95% CI, 29.9-53.2; I² = 98.3%), based on the results of the random-effect method used in this meta-analysis. Patients with Mendelian susceptibility to mycobacterial diseases had the highest frequency of BCG-VACs with a pooled frequency of 90.6% (95% CI, 79.7-1.0; I² = 81.1%).

CONCLUSIONS

Several PID entities are susceptible to BCG-VACs. Systemic neonatal PID screening programs may help to prevent a substantial amount of BCG vaccination complications.

Exportin-1-Dependent Nuclear Export of DEAD-box Helicase DDX3X is Central to its Role in Antiviral Immunity

DEAD-box helicase 3, X-linked (DDX3X) regulates the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR)-mediated antiviral response, but can also be a host factor contributing to the replication of viruses of significance to human health, such as human immunodeficiency virus type 1 (HIV-1). These roles are mediated in part through its ability to actively shuttle between the nucleus and the cytoplasm to modulate gene expression, although the trafficking mechanisms, and impact thereof on immune signaling and viral infection, are incompletely defined. We confirm that DDX3X nuclear export is mediated by the nuclear transporter exportin-1/CRM1, dependent on an N-terminal, leucine-rich nuclear export signal (NES) and the monomeric guanine nucleotide binding protein Ran in activated GTP-bound form. Transcriptome profiling and ELISA show that exportin-1-dependent export of DDX3X to the cytoplasm strongly impacts IFN-β production and the upregulation of immune genes in response to infection. That this is key to DDX3X's antiviral role was indicated by enhanced infection by human parainfluenza virus-3 (hPIV-3)/elevated virus production when the DDX3X NES was inactivated. Our results highlight a link between nucleocytoplasmic distribution of DDX3X and its role in antiviral immunity, with strong relevance to hPIV-3, as well as other viruses such as HIV-1.

Inherited IFNAR1 deficiency in otherwise healthy patients with adverse reaction to measles and yellow fever live vaccines

We describe two unrelated patients with inherited IFNAR1 deficiency who suffered from life-threatening infections following measles or yellow fever virus vaccination and were otherwise healthy.

Vaccination against measles, mumps, and rubella (MMR) and yellow fever (YF) with live attenuated viruses can rarely cause life-threatening disease. Severe illness by MMR vaccines can be caused by inborn errors of type I and/or III interferon (IFN) immunity (mutations in IFNAR2, STAT1, or STAT2). Adverse reactions to the YF vaccine have remained unexplained. We report two otherwise healthy patients, a 9-yr-old boy in Iran with severe measles vaccine disease at 1 yr and a 14-yr-old girl in Brazil with viscerotropic disease caused by the YF vaccine at 12 yr. The Iranian patient is homozygous and the Brazilian patient compound heterozygous for loss-of-function IFNAR1 variations. Patient-derived fibroblasts are susceptible to viruses, including the YF and measles virus vaccine strains, in the absence or presence of exogenous type I IFN. The patients’ fibroblast phenotypes are rescued with WT IFNAR1. Autosomal recessive, complete IFNAR1 deficiency can result in life-threatening complications of vaccination with live attenuated measles and YF viruses in previously healthy individuals.

Challenges and Clinical Implications of the Diagnosis of Cytomegalovirus Lung Infection in Children

PURPOSE OF REVIEW

Pulmonary cytomegalovirus (CMV) infection is a potential lethal disease in children, but it remains a diagnostic challenge. The differentiation between latent CMV infections with viral shedding and active infections is difficult and may lead to false positives in bronchoalvolar lavage (BAL) PCR detection. This review summarizes current diagnostic approaches for CMV lung infection in children including progress in the identification of underlying immune defects linked to this condition.

RECENT FINDINGS

There is increasing literature supporting that the combined assessment of host risk factors and lung disease pattern is essential for the diagnosis of pulmonary CMV infection in children. The most important host risk factor is an immunecompromised state that has expanded from primary or acquired immunodeficiency (e.g., HIV) to include a myriad of immune-dysregulation syndromes (e.g., CTLA4, PIK3 defects). Newborns, paricularly those born premature, are also a high-risk group. At the pulmonary level, active CMV infection is typically characterized by alveolar compromise leading to hypoxemia, ground-glass opacities, and intra-alveolar infiltrates with CMV inclusions in lung biopsy. The identification of active CMV lung infection should trigger additional evaluation of immune defects (primary or secondary) impairing T and NK cell function or innate antiviral responses as well as other immune dysregulation disorders. Lung CMV infections in children are more prevalent in immunocompromised hosts and premature newborns. Lung CMV infections should prompt further investigation into conditions altering immune mechanisms usually in place to contain CMV infections. Common clinical and radiological patterns such as hypoxemia and ground-glass pulmonary opacities may allow early identification and treatment of CMV lung infection and underlying causes in the pediatric population.

RNA Polymerase III as a Gatekeeper to Prevent Severe VZV Infections

In most individuals, varicella zoster virus (VZV) causes varicella upon primary infection and zoster during reactivation. However, in a subset of individuals, VZV may cause severe disease, including encephalitis. Host genetics is believed to be the main determinant of exacerbated disease manifestations. Recent studies have demonstrated that defects in the DNA sensor RNA polymerase III (POL III) confer selective increased susceptibility to VZV infection, thus providing fundamental new insight into VZV immunity. Here we describe the roles of POL III in housekeeping and immune surveillance during VZV infection. We present the latest knowledge on the role of POL III in VZV infection and discuss outstanding questions related to the role of POL III in VZV immunity, and how this insight can be translated into clinical medicine.

Impaired IL-12- and IL-23-Mediated Immunity Due to IL-12Rβ1 Deficiency in Iranian Patients with Mendelian Susceptibility to Mycobacterial Disease

PURPOSE

Inborn errors of IFN-γ-mediated immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD), which is characterized by an increased susceptibility to severe and recurrent infections caused by weakly virulent mycobacteria, such as Bacillus Calmette-Guérin (BCG) vaccines and environmental, nontuberculous mycobacteria (NTM).

METHODS

In this study, we investigated four patients from four unrelated consanguineous families from Isfahan, Iran, with disseminated BCG disease. We evaluated the patients' whole blood cell response to IL-12 and IFN-γ, IL-12Rβ1 expression on T cell blasts, and sequenced candidate genes.

RESULTS

We report four patients from Isfahan, Iran, ranging from 3 months to 26 years old, with impaired IL-12 signaling. All patients suffered from BCG disease. One of them presented mycobacterial osteomyelitis. By Sanger sequencing, we identified three different types of homozygous mutations in IL12RB1. Expression of IL-12Rβ1 was completely abolished in the four patients with IL12RB1 mutations.

CONCLUSIONS

IL-12Rβ1 deficiency was found in the four MSMD Iranian families tested. It is the first report of an Iranian case with S321* mutant IL-12Rβ1 protein. Mycobacterial osteomyelitis is another type of location of BCG infection in an IL-12Rβ1-deficient patient, notified for the first time in this study.

A digenic human immunodeficiency characterized by IFNAR1 and IFNGR2 mutations

Primary immunodeficiencies are often monogenic disorders characterized by vulnerability to specific infectious pathogens. Here, we performed whole-exome sequencing of a patient with disseminated Mycobacterium abscessus, Streptococcus viridians bacteremia, and cytomegalovirus (CMV) viremia and identified mutations in 2 genes that regulate distinct IFN pathways. The patient had a homozygous frameshift deletion in IFNGR2, which encodes the signal transducing chain of the IFN-γ receptor, that resulted in minimal protein expression and abolished downstream signaling. The patient also harbored a homozygous deletion in IFNAR1 (IFNAR1*557Gluext*46), which encodes the IFN-α receptor signaling subunit. The IFNAR1*557Gluext*46 resulted in replacement of the stop codon with 46 additional codons at the C-terminus. The level of IFNAR1*557Gluext*46 mutant protein expressed in patient fibroblasts was comparable to levels of WT IFNAR1 in control fibroblasts. IFN-α-induced signaling was impaired in the patient fibroblasts, as evidenced by decreased STAT1/STAT2 phosphorylation, nuclear translocation of STAT1, and expression of IFN-α-stimulated genes critical for CMV immunity. Pretreatment with IFN-α failed to suppress CMV protein expression in patient fibroblasts, whereas expression of WT IFNAR1 restored IFN-α-mediated suppression of CMV. This study identifies a human IFNAR1 mutation and describes a digenic immunodeficiency specific to type I and type II IFNs.

Recurrent and Sustained Viral Infections in Primary Immunodeficiencies

Viral infections are commonplace and often innocuous. Nevertheless, within the population of patients with primary immunodeficiencies (PIDDs), viral infections can be the feature that drives a diagnostic evaluation or can be the most significant morbidity for the patient. This review is focused on the viral complications of PIDDs. It will focus on respiratory viruses, the most common type of viral infection in the general population. Children and adults with an increased frequency or severity of respiratory viral infections are often referred for an immunologic evaluation. The classic teaching is to investigate humoral function in people with recurrent sinopulmonary infections, but this is often interpreted to mean recurrent bacterial infections. Recurrent or very severe viral infections may also be a harbinger of a primary immunodeficiency as well. This review will also cover persistent cutaneous viral infections, systemic infections, central nervous system infections, and gastrointestinal infections. In each case, the specific viral infections may drive a diagnostic evaluation that is specific for that type of virus. This review also discusses the management of these infections, which can become problematic in patients with PIDDs.

Deletion of the entire interferon-γ receptor 1 gene causing complete deficiency in three related patients

PURPOSE

Complete interferon-γ receptor 1 (IFN-γR1) deficiency is a primary immunodeficiency causing predisposition to severe infection due to intracellular pathogens. Only 36 cases have been reported worldwide. The purpose of this article is to describe a large novel deletion found in 3 related cases, which resulted in the complete removal of the IFNGR1 gene.

METHODS

Whole blood from three patients was stimulated with lipopolysaccharide (LPS) and IFN-γ to determine production of tumor necrosis factor (TNF), interleukin-12 p40 (IL-12p40) and IL-10. Expression of IFN-γR1 on the cell membrane of patients' monocytes was assessed using flow cytometry. IFNGR1 transcript was analyzed in RNA and the gene and adjacent regions were analyzed in DNA. Finally, IL22RA2 transcript levels were analyzed in whole blood cells and dendritic cells.

RESULTS

There was no expression of the IFN-γR1 on the monocytes. Consistent with this finding, there was no IFN-γ response in the whole blood assay as measured by effect on LPS-induced IL-12p40, TNF and IL-10 production. A 119.227 nt homozygous deletion on chromosome 6q23.3 was identified, removing the IFNGR1 gene completely and ending 117 nt upstream of the transcription start of the IL22RA2 gene. Transcript levels of IL22RA2 were similar in patient and control.

CONCLUSIONS

We identified the first large genomic deletion of IFNGR1 causing complete IFN-γR1 deficiency. Despite the deletion ending very close to the IL22RA2 gene, it does not appear to affect IL22RA2 transcription and, therefore, may not have any additional clinical consequence.

Aqueous Tear Deficiency Increases Conjunctival Interferon-γ (IFN-γ) Expression and Goblet Cell Loss

PURPOSE

To investigate the hypothesis that increased interferon-γ (IFN-γ) expression is associated with conjunctival goblet cell loss in subjects with tear dysfunction.

METHODS

Goblet cell density (GCD) was measured in impression cytology from the temporal bulbar conjunctiva, and gene expression was measured in cytology samples from the nasal bulbar conjunctiva obtained from 68 subjects, including normal control, meibomian gland disease (MGD), non-Sjögren syndrome (non-SSATD)-, and Sjögren syndrome (SSATD)-associated aqueous tear deficiency. Gene expression was evaluated by real-time PCR. Tear meniscus height (TMH) was measured by optical coherence tomography. Fluorescein and lissamine green dye staining evaluated corneal and conjunctival disease, respectively. Between-group mean differences and correlation coefficients were calculated.

RESULTS

Compared to control, IFN-γ expression was significantly higher in both ATD groups, and its receptor was higher in SSATD. Expression of IL-13 and its receptor was similar in all groups. Goblet cell density was lower in the SSATD group; expression of MUC5AC mucin was lower and cornified envelope precursor small proline-rich region (SPRR)-2G higher in both ATD groups. Interferon-γ transcript number was inversely correlated with GCD (r = -0.37, P < 0.04) and TMH (r = -0.37, P = 0.02), and directly correlated with lissamine green staining (r = 0.51, P < 0.001) and SPRR-2G expression (r = 0.32, P < 0.05).

CONCLUSIONS

Interferon-γ expression in the conjunctiva was higher in aqueous deficiency and correlated with goblet cell loss and severity of conjunctival disease. These results support findings of animal and culture studies showing that IFN-γ reduces conjunctival goblet cell number and mucin production.

Recent considerations in the use of recombinant interferon gamma for biological therapy of atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is the most common inflammatory skin disease in the general population. There are different endophenotypes of AD that likely have a unique immune and molecular basis, such as those who are predisposed to eczema herpeticum, or Staphylococcus aureus infections.

AREAS COVERED

In this review, we highlight the endophenotypes of AD where reduced interferon gamma expression may be playing a role. Additionally, we review the potential role of recombinant interferon gamma therapy in the treatment of atopic dermatitis and the particular phenotypes that may benefit from this treatment.

EXPERT OPINION

Recombinant interferon gamma treatment will likely benefit the pediatric population with AD, as well as those with susceptibilities for skin infections. Future studies are needed to elucidate whether IFN-γ may reduce the prevalence of skin infection in AD.

A genetic perspective on granulomatous diseases with an emphasis on mycobacterial infections

Identification of the genetic factors predisposing to mycobacterial infections has been a subject of intense research activities. Current knowledge of the genetic and immunological basis of susceptibility to mycobacteria largely comes from natural human and experimental models of Bacille Calmette Guérin (BCG) and nontuberculous mycobacterial infections. These observations support the central role of the IL-12/IFN-γ pathway in controlling mycobacterial infection. In this review, we discuss the knowledge that associates both simple and complex inheritance with susceptibility to mycobacterial diseases. We place a special emphasis on monogenic disorders, since these clearly pinpoint pathways and can adduce mechanism. We also describe the clinical, immunological, and pathological features that may steer clinical investigation in the appropriate directions.

Host susceptibility to non-tuberculous mycobacterial infections

Non-tuberculous mycobacteria cause a broad range of clinical disorders, from cutaneous infections, such as cervical or intrathoracic lymphadenitis in children, to disseminated infections at all ages. Recognition of the underlying immune defect is crucial for rational treatment, preventive care, family screening, and, in some cases, transplantation. So far, at least seven autosomal mutations (in IL12B, IL12RB1, ISG15, IFNGR1, IFNGR2, STAT1, and IRF8) and two X-linked mutations (in IKBKG and CYBB), mostly presenting in childhood, have been reported to confer susceptibility to disseminated non-tuberculous mycobacterial infection. GATA2 deficiency and anti-interferon γ autoantibodies also give rise to disseminated infection, typically in late childhood or adulthood. Furthermore, isolated pulmonary non-tuberculous mycobacterial infection has been increasing in prevalence in people without recognised immune dysfunction. In this Review, we discuss how to detect and differentiate host susceptibility factors underlying localised and systemic non-tuberculous mycobacterial infections.

Mendelian susceptibility to mycobacterial disease: genetic, immunological, and clinical features of inborn errors of IFN-γ immunity

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare condition characterized by predisposition to clinical disease caused by weakly virulent mycobacteria, such as BCG vaccines and environmental mycobacteria, in otherwise healthy individuals with no overt abnormalities in routine hematological and immunological tests. MSMD designation does not recapitulate all the clinical features, as patients are also prone to salmonellosis, candidiasis and tuberculosis, and more rarely to infections with other intramacrophagic bacteria, fungi, or parasites, and even, perhaps, a few viruses. Since 1996, nine MSMD-causing genes, including seven autosomal (IFNGR1, IFNGR2, STAT1, IL12B, IL12RB1, ISG15, and IRF8) and two X-linked (NEMO, and CYBB) genes have been discovered. The high level of allelic heterogeneity has already led to the definition of 18 different disorders. The nine gene products are physiologically related, as all are involved in IFN-γ-dependent immunity. These disorders impair the production of (IL12B, IL12RB1, IRF8, ISG15, NEMO) or the response to (IFNGR1, IFNGR2, STAT1, IRF8, CYBB) IFN-γ. These defects account for only about half the known MSMD cases. Patients with MSMD-causing genetic defects may display other infectious diseases, or even remain asymptomatic. Most of these inborn errors do not show complete clinical penetrance for the case-definition phenotype of MSMD. We review here the genetic, immunological, and clinical features of patients with inborn errors of IFN-γ-dependent immunity.

Sustained inflammation and differential expression of interferons type I and III in PVM-infected interferon-gamma (IFNγ) gene-deleted mice

Interferon gamma (IFNγ) has complex immunomodulatory and antiviral properties. While IFNγ is detected in the airways in response to infection with the pneumovirus pathogen, pneumonia virus of mice (PVM; Family Paramyxoviridae), its role in promoting disease has not been fully explored. Here, we evaluate PVM infection in IFNγ(-/-) mice. Although the IFNγ gene-deletion has no impact on weight loss, survival or virus kinetics, expression of IFNβ, IFNλ2/3 and IFN-stimulated 2-5' oligoadenylate synthetases was significantly diminished compared to wild-type counterparts. Furthermore, PVM infection in IFNγ(-/-) mice promoted prominent inflammation, including eosinophil and neutrophil infiltration into the airways and lung parenchyma, observed several days after peak virus titer. Potential mechanisms include over-production of chemoattractant and eosinophil-active cytokines (CXCL1, CCL11, CCL3 and IL5) in PVM-infected IFNγ(-/-) mice; likewise, IFNγ actively antagonized IL5-dependent eosinophil survival ex vivo. Our results may have clinical implications for pneumovirus infection in individuals with IFNγ signaling defects.

Epidemiology of infections in cancer patients

Although major advances in the care of cancer patients over the past several decades have resulted in improved survival, infectious complications remain a significant cause of morbidity and mortality. To successfully identify, treat, and prevent infections, a comprehensive understanding of risk factors that predispose to infection and of commonly encountered pathogens is necessary. In addition, clinicians must keep abreast of the changing epidemiology of infections in this population. As therapeutic modalities continue to evolve, as established pathogens become increasingly drug resistant, and as new pathogens are discovered, successful management of infections will continue to present challenges in the years to come.

Nontuberculous mycobacterial infections in children with inborn errors of the immune system

Severe mycobacterial disease is mostly confined to patients who are immunocompromized either by acquired or inherited causes. One such genetic disorder is Mendelian Susceptibility to Mycobacterial Disease (MSMD), a hot topic within the field of primary immunodeficiency. This single gene disorder is characterized by isolated infection with mycobacteria or Salmonella due to a defect in the type-1 cytokine response. In the last two decades, ten genes have been labeled as causing MSMD when they harbor germline mutations, namely IL12B, IL12RB1, IFNGR1, IFNGR2, STAT1, IKBKG, CYBB, TYK2, IRF8 and ISG15. The mutations lead to either insufficient production of IFN-γ, or to an insufficient response to the cytokine. Current treatment options include recombinant IFN-γ and hematologic stem cell transplantation (HSCT). In the future, gene therapy, antisense-mediated exon skipping and chemical intervention in glycosylation problems may become successful alternatives. Furthermore, it is likely that many new candidate genes and pathways crucial for mycobacterial immunity will be identified.

Genome-wide mouse mutagenesis reveals CD45-mediated T cell function as critical in protective immunity to HSV-1

Herpes simplex encephalitis (HSE) is a lethal neurological disease resulting from infection with Herpes Simplex Virus 1 (HSV-1). Loss-of-function mutations in the UNC93B1, TLR3, TRIF, TRAF3, and TBK1 genes have been associated with a human genetic predisposition to HSE, demonstrating the UNC93B-TLR3-type I IFN pathway as critical in protective immunity to HSV-1. However, the TLR3, UNC93B1, and TRIF mutations exhibit incomplete penetrance and represent only a minority of HSE cases, perhaps reflecting the effects of additional host genetic factors. In order to identify new host genes, proteins and signaling pathways involved in HSV-1 and HSE susceptibility, we have implemented the first genome-wide mutagenesis screen in an in vivo HSV-1 infectious model. One pedigree (named P43) segregated a susceptible trait with a fully penetrant phenotype. Genetic mapping and whole exome sequencing led to the identification of the causative nonsense mutation L3X in the Receptor-type tyrosine-protein phosphatase C gene (Ptprc(L3X)), which encodes for the tyrosine phosphatase CD45. Expression of MCP1, IL-6, MMP3, MMP8, and the ICP4 viral gene were significantly increased in the brain stems of infected Ptprc(L3X) mice accounting for hyper-inflammation and pathological damages caused by viral replication. Ptprc(L3X) mutation drastically affects the early stages of thymocytes development but also the final stage of B cell maturation. Transfer of total splenocytes from heterozygous littermates into Ptprc(L3X) mice resulted in a complete HSV-1 protective effect. Furthermore, T cells were the only cell population to fully restore resistance to HSV-1 in the mutants, an effect that required both the CD4⁺ and CD8⁺ T cells and could be attributed to function of CD4⁺ T helper 1 (Th1) cells in CD8⁺ T cell recruitment to the site of infection. Altogether, these results revealed the CD45-mediated T cell function as potentially critical for infection and viral spread to the brain, and also for subsequent HSE development.

B-cell lymphoma in a patient with complete interferon gamma receptor 1 deficiency

Immunosuppression-associated lymphoproliferative disorders can be related to primary as well as acquired immune disorders. Interferon gamma receptor (IFN-γR) deficiency is a rare primary immune disorder, characterized by increased susceptibility to mycobacterial infections. Here we report the first case of an Epstein Barr Virus (EBV) related B-cell lymphoma in a patient with complete IFN-γR1 deficiency. The patient was a 20-year-old man with homozygous 22Cdel in IFNGR1 resulting in complete absence of IFN-γR1 surface expression and complete lack of responsiveness to IFN-γ in vitro. He had disseminated refractory Mycobacterium avium complex and Mycobacterium abscessus infections. At age 18 he presented with new spiking fever and weight loss that was due to an EBV-positive B-cell non-Hodgkin lymphoma. Two years later he died of progressive lymphoma. IFN-γ plays an important role in tumor protection and rejection. Patients with IFN-γR deficiencies and other immune deficits predisposing to mycobacterial disease seem to have an increased risk of malignancies, especially those related to viral infections. As more of these patients survive their early infections, cancer awareness and tumor surveillance may need to become a more routine part of management.

Anti–IFN-γ autoantibodies in adults with disseminated nontuberculous mycobacterial infections are associated with HLA-DRB1*16:02 and HLA-DQB1*05:02 and the reactivation of latent varicella-zoster virus infection

Anti–IFN-γ autoantibodies are associated with HLA-DRB1*16:02 and DQB1*05:02.

Genetic lessons learned from X-linked Mendelian susceptibility to mycobacterial diseases

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare syndrome conferring predisposition to clinical disease caused by weakly virulent mycobacteria, such as Mycobacterium bovis Bacille Calmette Guérin (BCG) vaccines and nontuberculous, environmental mycobacteria (EM). Since 1996, MSMD-causing mutations have been found in six autosomal genes involved in IL-12/23-dependent, IFN-γ-mediated immunity. The aim of this review is to provide the description of the two described forms of X-linked recessive (XR) MSMD. Germline mutations in two genes, NEMO and CYBB, have long been known to cause other human diseases-incontinentia pigmenti (IP) and anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) (NEMO/IKKG), and X-linked chronic granulomatous disease (CGD) (CYBB)-but specific mutations in either of these two genes have recently been shown to cause XR-MSMD. NEMO is an essential component of several NF-κB-dependent signaling pathways. The MSMD-causing mutations in NEMO selectively affect the CD40-dependent induction of IL-12 in mononuclear cells. CYBB encodes gp91(phox) , which is an essential component of the NADPH oxidase in phagocytes. The MSMD-causing mutation in CYBB selectively affects the respiratory burst in macrophages. Mutations in NEMO and CYBB may therefore cause MSMD by selectively exerting their deleterious impact on a single signaling pathway (CD40-IL-12, NEMO) or a single cell type (macrophages, CYBB). These experiments of Nature illustrate how specific germline mutations in pleiotropic genes can dissociate signaling pathways or cell lineages, thereby resulting in surprisingly narrow clinical phenotypes.

Severe viral infections and primary immunodeficiencies

Patients with severe viral infections are often not thoroughly evaluated for immunodeficiencies. In this review, we summarize primary immunodeficiencies that predispose individuals to severe viral infections. Some immunodeficiencies enhance susceptibility to disease with a specific virus or family of viruses, whereas others predispose to diseases with multiple viruses in addition to disease with other microbes. Although the role of cytotoxic T cells in controlling viral infections is well known, a number of immunodeficiencies that predispose to severe viral diseases have recently been ascribed to defects in the Toll-like receptor-interferon signaling pathway. These immunodeficiencies are rare, but it is important to identify them both for prognostic information and for genetic counseling. Undoubtedly, additional mutations in proteins in the innate and adaptive arms of the immune system will be identified in the future, which will reveal the importance of these proteins in controlling infections caused by viruses and other pathogens.

Partial recessive IFN-γR1 deficiency: genetic, immunological and clinical features of 14 patients from 11 kindreds

We report a series of 14 patients from 11 kindreds with recessive partial (RP)-interferon (IFN)-γR1 deficiency. The I87T mutation was found in nine homozygous patients from Chile, Portugal and Poland, and the V63G mutation was found in five homozygous patients from the Canary Islands. Founder effects accounted for the recurrence of both mutations. The most recent common ancestors of the patients with the I87T and V63G mutations probably lived 1600 (875-2950) and 500 (200-1275) years ago, respectively. The two alleles confer phenotypes that are similar but differ in terms of IFN-γR1 levels and residual response to IFN-γ. The patients suffered from bacillus Calmette-Guérin-osis (n= 6), environmental mycobacteriosis (n= 6) or tuberculosis (n= 1). One patient did not suffer from mycobacterial infections but had disseminated salmonellosis, which was also present in two other patients. Age at onset of the first environmental mycobacterial disease differed widely between patients, with a mean value of 11.25 ± 9.13 years. Thirteen patients survived until the age of 14.82 ± 11.2 years, and one patient died at the age of 7 years, 9 days after the diagnosis of long-term Mycobacterium avium infection and the initiation of antimycobacterial treatment. Up to 10 patients are currently free of infection with no prophylaxis. The clinical heterogeneity of the 14 patients was not clearly related to either IFNGR1 genotype or the resulting cellular phenotype. RP-IFN-γR1 deficiency is, thus, more common than initially thought and should be considered in both children and adults with mild or severe mycobacterial diseases.

A comparative transcriptomic study of vitamin E and an algae-based antioxidant as antioxidative agents: investigation of replacing vitamin E with the algae-based antioxidant in broiler diets

Previous study indicated that inclusion of an algae-based antioxidant as an antioxidative agent [EconomasE, Alltech, Nicholasville, KY; EcoE] significantly reduced the amount of vitamin E (VE) required in broiler diets without compromising performance and meat quality. To assess the mechanisms related to the VE-saving activity of EcoE, as well as other potential functions related to EcoE and VE supplementation, we analyzed gene expression profiles of breast muscle from broilers fed a control diet, the control diet + 50 IU of VE/kg, the control diet + 100 IU of VE/kg, or the control diet + 200 g of EcoE/ton. Evaluation of the serum antioxidant capacity indicated that dietary supplementation of either a high level of VE (50 or 100 IU of VE/kg) or EcoE significantly improved bird antioxidant status. Analysis of gene expression profiles indicated that expression of 542 genes of the breast muscle were altered (P < 0.05, fold change >1.2) by dietary treatments, of which a significant part were commonly regulated by EcoE and VE (especially the control diet + 50 IU of VE/kg). In addition to the process of cellular oxidation, gene ontology analysis indicated the involvement of EcoE and VE on cell morphology, skeletal and muscular system development and function, immune response, and multiple metabolic processes, including lipid, carbohydrate, and drug metabolism. Results of this experiment indicate that the biological roles of high VE, including its activity as an antioxidant, can be greatly mimicked at the transcriptional level by EcoE, and they suggest a relationship of functional redundancy between VE and EcoE in the broiler diets.

Meningoencephalitis caused by varicella-zoster virus reactivation in a child with dominant partial interferon-gamma receptor-1 deficiency

We describe a previously symptom-free 13-year-old boy with dominant partial interferon-γ receptor-1 deficiency and unusual varicella-zoster virus reactivation. This case supports the unsettled notion that some interferon-γ R-deficient patients are at enhanced risk for viral disease.

Genomic structure and characterization of mRNA expression pattern of porcine interferon gamma receptor 1 gene

Interferon gamma receptor (IFNGR) plays an important role in the biological effects of IFN-γ. In this study, porcine IFNGR1 cDNA was cloned and two transcripts both having a coding region of 1413 bp were identified. Porcine IFNGR1 cDNA shares 62.95%, 63.73%, 72.90% and 81.10% identity in nucleotide sequence; and 45.64%, 46.69%, 58.04% and 72.55% homology in amino acid sequence to those of rat, mouse, human and cattle, respectively. The porcine IFNGR1 genomic structure consists of seven exons and six introns and is located on porcine chromosome 1. The mRNA expression of porcine IFNGR1 gene is detected in all tissues examined, with strong expression in spleen and liver tissues and weak expression in cerebrum, cerebellum and uterus tissues, respectively. A different developmental pattern in IFNGR1 mRNA expression between Laiwu and Duroc breeds was revealed by real-time quantitative RT-PCR: in Duroc pigs, a significantly higher expression was found in the tissues of heart (P<0.05), liver (P<0.01), kidney (P<0.01) and skeletal muscle (P<0.05) of adult pigs compared to piglets. In porcine reproductive and respiratory syndrome virus (PRRSV)-infected Dapulian pigs, compared to the uninfected ones, the expression level of IFNGR1 mRNA in spleen was significantly up-regulated (P<0.05), whereas its expression in the lymph node was significantly down-regulated (P<0.05); in PRRSV-infected Duroc × Yorkshire × Landrace commercial pigs, however, the differences both in spleen and lymph node tissues were not significant.