Augmentation of antitubercular therapy with IFNγ in a patient with dominant partial IFNγ receptor 1 deficiency

Disseminated mycobacterium avium complex spinal osteomyelitis in a patient with interferon gamma receptor deficiency: A case report

Disseminated mycobacterium avium complex (MAC) infection is rare and is classically associated with immunodeficient states. Osteomyelitis is a rare manifestation of disseminated MAC infection. The overwhelming majority of MAC infections occur in patients with human immunodeficiency virus (HIV). Disseminated MAC infection has been described in interferon gamma receptor deficiency, an immunodeficiency mechanistically linked to mycobacterial infection. We present a case of disseminated MAC vertebral osteomyelitis in a patient with interferon gamma receptor deficiency.

Novel STAT1 Variants in Japanese Patients with Isolated Mendelian Susceptibility to Mycobacterial Diseases

PURPOSE

Heterozygous dominant-negative (DN) STAT1 variants are responsible for autosomal dominant (AD) Mendelian susceptibility to mycobacterial disease (MSMD). In this paper, we describe eight MSMD cases from four kindreds in Japan.

METHODS

An inborn error of immunity-related gene panel sequencing was performed using genomic DNA extracted from whole blood samples. The identified variants were validated using Sanger sequencing. Functional analysis was evaluated with a luciferase reporter assay and co-transfection assay in STAT1-deficient cells.

RESULTS

Patient 1.1 was a 20-month-old boy with multifocal osteomyelitis and paravertebral abscesses caused by Mycobacterium bovis bacillus Calmette-Guérin (BCG). Although the paravertebral abscess was refractory to antimycobacterial drugs, the addition of IFN-γ and drainage of the abscess were effective. Intriguingly, his mother (patient 1.2) showed an uneventful clinical course except for treatment-responsive tuberculous spondylitis during adulthood. Patient 2.1 was an 8-month-old boy with lymphadenopathy and lung nodules caused by BCG. He responded well to antimycobacterial drugs. His mother (patient 2.2) was healthy. Patient 3.1 was a 11-year-old girl with suspected skin tuberculosis. Her brother (patient 3.2) had BCG-osis, but their mother (patient 3.3) was healthy. Patient 4 was an 8-month-old girl with left axillary and supraclavicular lymphadenopathy associated with BCG vaccination. Kindreds 1, 2, and 3 were shown to have novel heterozygous variants (V642F, R588C, and R649G) in STAT1, respectively. Kindred 4 had previously reported heterozygous variants (Q463H). A luciferase reporter assay in STAT1-deficient cells followed by IFN-γ stimulation confirmed that these variants are loss-of-function. In addition, with co-transfection assay, we confirmed all of these variants had DN effect on WT STAT1.

CONCLUSION

Four kindred MSMD subjects with 3 novel variants and 1 known variant in STAT1 were identified in this study. AD STAT1 deficiency might be prevalent in Japanese patients with BCG-associated MSMD.

Early diagnosis of partial interferon-γ receptor 1 deficiency prevents the development of Bacille de Calmette et Guérin osteomyelitis

We encountered two patients with partial interferon γ receptor 1 (IFN-γR1) deficiency in whom early diagnosis enhanced disease management. Patient 1 was a 44-year-old woman with enlarged lymph nodes diagnosed in a pre-pregnancy checkup, and pathological examination revealed a Mycobacterium avium infection. Based on her history of unknown multiple osteomyelitis during early childhood, mendelian susceptibility to mycobacterial disease was suspected. Genetic analysis revealed a novel heterozygous variant in IFNGR1. Genetic counseling was administered to the patient and her husband before they had their baby. Patient 2 was a 4-month-old boy whose father was previously diagnosed with autosomal dominant IFN-γR1 deficiency owing to Bacille de Calmette et Guérin (BCG) osteomyelitis. Genetic analysis showed that he had the same INFGR1 variant. He avoided BCG vaccination and has been disease-free since then. Early diagnosis is considered to be useful for genetic counseling and essential for preventing BCG osteomyelitis.

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.

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.

Mutual alteration of NOD2-associated Blau syndrome and IFNγR1 deficiency

Blau syndrome (BS) is an auto-inflammatory granulomatous disease that possibly involves abnormal response to interferon gamma (IFNγ) due to exaggerated nucleotide-binding oligomerization domain containing 2 (NOD2) activity. Mendelian susceptibility to mycobacterial diseases (MSMD) is an infectious granulomatous disease that is caused by impaired production of or response to IFNγ. We report a mother and daughter who are both heterozygous for NOD2c.2264C˃T variant and dominant-negative IFNGR1818del4 mutation. The 17-year-old patient displayed an altered form of BS and milder form of MSMD, whereas the 44-year-old mother was completely asymptomatic. This experiment of nature supports the notion that IFNγ is an important driver of at least some BS manifestations and that elucidation of its involvement in the disease immunopathogenesis may identify novel therapeutic targets.

Laboratory evaluation of the IFN-γ circuit for the molecular diagnosis of Mendelian susceptibility to mycobacterial disease

The integrity of the interferon (IFN)-γ circuit is necessary to mount an effective immune response to intra-macrophagic pathogens, especially Mycobacteria. Inherited monogenic defects in this circuit that disrupt the production of, or response to, IFN-γ underlie a primary immunodeficiency known as Mendelian susceptibility to mycobacterial disease (MSMD). Otherwise healthy patients display a selective susceptibility to clinical disease caused by poorly virulent mycobacteria such as BCG (bacille Calmette-Guérin) vaccines and environmental mycobacteria, and more rarely by other intra-macrophagic pathogens, particularly Salmonella and M. tuberculosis. There is high genetic and allelic heterogeneity, with 19 genetic etiologies due to mutations in 10 genes that account for only about half of the patients reported. An efficient laboratory diagnostic approach to suspected MSMD patients is important, because it enables the establishment of specific therapeutic measures that will improve the patient's prognosis and quality of life. Moreover, it is essential to offer genetic counseling to affected families. Herein, we review the various genetic and immunological diagnostic approaches that can be used in concert to reach a molecular and cellular diagnosis in patients with MSMD.

An Update on the Use of Immunomodulators in Primary Immunodeficiencies

The genomic revolution in the past decade fuelled by breathtaking advances in sequencing technologies has defined several new genetic diseases of the immune system. Many of these newly characterized diseases are a result of defects in genes involved in immune regulation. The discovery of these diseases has opened a vista of new therapeutic possibilities. Immunomodulatory agents, a hitherto unexplored therapeutic option in primary immunodeficiency diseases have been tried in a host of these newly described maladies. These agents have been shown conclusively to favorably modulate immune responses, resulting in abatement of clinical manifestations both in experimental models and patients. While some of the treatment options have been approved for therapeutic use or have been shown to be of merit in open-label trials, others have been shown to be efficacious in a handful of clinical cases, animal models, and cell lines. Interferon γ is approved for use in chronic granulomatous disease (CGD) to reduce the burden of infection and and has a good long-term efficacy. Recombinant human IL7 therapy has been shown increase the peripheral CD4 and CD8 T cell counts in patients with idiopathic CD4. Anti-IL1 agents are approved for the management of cryopyrin-related autoinflammatory syndrome, and their therapeutic efficacy is being increasingly recognized in other autoinflammatory syndromes and CGD. Mammalian target of rapamycin (mTOR) inhibitors have been proven useful in autoimmune lymphoproliferative syndrome (ALPS) and in IPEX syndrome. Therapies reported to be potential use in case reports include abatacept in CTLA4 haploinsufficiency and LRBA deficiency, ruxolitinib in gain-of-function STAT1, tocilizumab in gain-of-function STAT3 defect, mTOR inhibitors in PIK3CD activation, magnesium in XMEN syndrome, and pioglitazone in CGD. Treatment options of merit in human cell lines include interferon α and interferon β in TLR3 and UNC-93B deficiencies, anti-interferon therapy in SAVI, and Rho-kinase inhibitors in TTC7A deficiency. Anti-IL17 agents have show efficacy in animal models of leukocyte adhesion defect (LAD) and ALPS. This topical review explores the use of various immunomodulators and other biological agents in the context of primary immunodeficiency and autoinflammatory diseases.

'"Why me, why now?" Using clinical immunology and epidemiology to explain who gets nontuberculous mycobacterial infection

BACKGROUND

The prevalence of nontuberculous mycobacterial (NTM) disease is rising. An understanding of known risk factors for disease sheds light on the immunological and physical barriers to infection, and how and why they may be overcome. This review focuses on human NTM infection, supported by experimental and in vitro data of relevance to the practising clinician who seeks to understand why their patient has NTM infection and how to further investigate.

DISCUSSION

First, the underlying immune response to NTM disease is examined. Important insights regarding NTM disease susceptibility come from nature's own knockouts, the primary immune deficiency disorders. We summarise the current knowledge surrounding interferon-gamma (IFNγ)-interleukin-12 (IL-12) axis abnormalities, followed by a review of phagocytic defects, T cell lymphopenia and rarer genetic conditions known to predispose to NTM disease. We discuss how these define key immune pathways involved in the host response to NTM. Iatrogenic immunosuppression is also important, and we evaluate the impact of novel biological therapies, as well as bone marrow transplant and chemotherapy for solid organ malignancy, on the epidemiology and presentation of NTM disease, and discuss the host defence dynamics thus revealed. NTM infection and disease in the context of other chronic illnesses including HIV and malnutrition is reviewed. The role of physical barriers to infection is explored. We describe how their compromise through different mechanisms including cystic fibrosis, bronchiectasis and smoking-related lung disease can result in pulmonary NTM colonisation or infection. We also summarise further associations with host factors including body habitus and age. We use the presented data to develop an over-arching model that describes human host defences against NTM infection, where they may fail, and how this framework can be applied to investigation in routine clinical practice.

Gene expression and TB pathogenesis in rhesus macaques: TR4, CD40, CD40L, FAS (CD95), and TNF are host genetic markers in peripheral blood mononuclear cells that are associated with severity of TB lesions

Tuberculosis (TB) pathologic lesions in rhesus macaques resemble those in humans. The expression levels of several host TB candidate genes in the peripheral blood mononuclear cells (PBMCs) of six rhesus macaques experimentally infected with Mycobacterium tuberculosis were quantified pre-infection and at several dates post-infection. Quantitative measures of TB histopathology in the lungs including: granuloma count, granuloma size, volume of granulomatous and non-granulomatous lesions, and direct bacterial load, were used as the outcomes of a multi-level Bayesian regression model in which expression levels of host genes at various dates were used as predictors. The results indicate that the expression levels of TR4, CD40, CD40L, FAS (CD95) and TNF in PBMC were associated with quantitative measures of the severity of TB histopathologic lesions in the lungs of the study animals. Moreover, no reliable association between the expression levels of IFNE in PBMCs and the severity of TB lesions in the lungs of the study animals was found. In conclusion, PBMC expression profiles derived from the above-listed host genes might be appropriate biomarkers for probabilistic diagnosis and/or prognosis of TB severity in rhesus macaques.

Disseminated Mycobacterium avium complex infection in a child with partial dominant interferon gamma receptor 1 deficiency in India

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare condition characterized by clinical disease caused by weakly virulent mycobacteria. All genes mutated in MSMD patients are involved in IFN-γ immunity. Autosomal partial dominant (PD) interferon-γ receptor 1 (IFN-γR1) deficiency is the most frequent abnormality affecting the group of MSMD patients leading to impaired response of IFN-γ. We describe here a patient from India with disseminated infection due to Mycobacterium avium intracellulare (MAC) including multifocal osteomyelitis and BCG disease. A heterozygous mutation in exon 6 of IFNGR1 gene was identified, conferring an autosomal PD IFN-γR1 deficiency. Patient had recurrence of mycobacterial disease during antibiotic therapy for which subcutaneous IFN-γ was added as a modality of treatment for resistant MAC infection.

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.