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In recent decades, the prevalence of inborn errors of immunity has increased, necessitating the development of more effective treatment and care options for these highly morbid conditions. Due to these "experiments of nature," the complicated nature of the immune system is being revealed. Based on the functional and molecular tests, targeted therapies are now being developed which offer a more effective approach and reduce damage. This study aimed to investigate a key cytokine of the cellular immune response, interferon-gamma (IFN-γ), which is linked to Mendelian susceptibility to Mycobacterial disease, and its potential as a therapeutic option for IFN-γ deficiency. [ABSTRACT FROM AUTHOR]

Purpose: Inborn errors of IFN-γ immunity underlie Mendelian susceptibility to mycobacterial disease (MSMD). Twenty-two genes with products involved in the production of, or response to, IFN-γ and variants of which underlie MSMD have been identified. However, pathogenic variants of IFNG encoding a defective IFN-γ have been described in only two siblings, who both underwent hematopoietic stem cell transplantation (HCST). Methods: We characterized a new patient with MSMD by genetic, immunological, and clinical means. Therapeutic decisions were taken on the basis of these findings. Results: The patient was born to consanguineous Turkish parents and developed bacillus Calmette-Guérin (BCG) disease following vaccination at birth. Whole-exome sequencing revealed a homozygous private IFNG variant (c.224 T > C, p.F75S). Upon overexpression in recipient cells or constitutive expression in the patient's cells, the mutant IFN-γ was produced within the cells but was not correctly folded or secreted. The patient was treated for 6 months with two or three antimycobacterial drugs only and then for 30 months with subcutaneous recombinant IFN-γ1b plus two antimycobacterial drugs. Treatment with IFN-γ1b finally normalized all biological parameters. The patient presented no recurrence of mycobacterial disease or other related infectious diseases. The treatment was well tolerated, without the production of detectable autoantibodies against IFN-γ. Conclusion: We describe a patient with a new form of autosomal recessive IFN-γ deficiency, with intracellular, but not extracellular IFN-γ. IFN-γ1b treatment appears to have been beneficial in this patient, with no recurrence of mycobacterial infection over a period of more than 30 months. This targeted treatment provides an alternative to HCST in patients with complete IFN-γ deficiency or at least an option to better control mycobacterial infection prior to HCST. [ABSTRACT FROM AUTHOR]

Purpose: The first molecular evidence of a monogenic predisposition to mycobacteria came from the study of Mendelian susceptibility to mycobacterial disease (MSMD). We aimed to study this Mendelian susceptibility to mycobacterial diseases in Moroccan kindreds through clinical, immunological, and genetic analysis. Methods: Patients presented with clinical features of MSMD were recruited into this study. We used whole blood samples from patients and age-matched healthy controls. To measure IL-12 and IFN-γ production, samples were activated by BCG plus recombinant human IFN-γ or recombinant human IL-12. Immunological assessments and genetic analysis were also done for patients and their relatives. Results: Our study involved 22 cases from 15 unrelated Moroccan kindreds. The average age at diagnosis is 4 years. Fourteen patients (64%) were born to consanguineous parents. All patients were vaccinated with the BCG vaccine, and twelve of them (55%) developed locoregional or disseminated BCG infections. The other symptomatic patients had severe tuberculosis and/or recurrent salmonellosis. Genetic mutations were identified on the following genes: IL12RB1 in 8 patients, STAT1 in 7 patients; SPPL2A, IFNGR1, and TYK2 in two patients each; and TBX21 in one patient, with different modes of inheritance. All identified mutations/variants altered production or response to IFN-γ or both. Conclusion: Severe forms of tuberculosis and complications of BCG vaccination may imply a genetic predisposition present in the Moroccan population. In the presence of these infections, systematic genetic studies became necessary. BCG vaccination is contraindicated in MSMD patients and should be delayed in newborn siblings until the exclusion of a genetic predisposition to mycobacteria. [ABSTRACT FROM AUTHOR]

Background: Post-vaccination BCG disease typically attests to underlying inborn errors of immunity (IEIs), with the highest rates of complications in patients with Mendelian susceptibility to mycobacterial disease (MSMD). However, therapeutic protocols for the management of BCG-osis (disseminated) and persistent BCG-itis (localized) are still controversial. Methods: Twenty-four Iranian patients with MSMD (BCG-osis or BCG-itis), followed from 2009 to 2020 in Tehran, were included in the study. Their medical records were retrospectively reviewed for demographics, clinical features, laboratory findings, and molecular diagnosis. The therapeutic protocol sheets were prepared to contain the types and duration of anti-mycobacterial agents. Results: BCG disease either as BCG-itis (33.3%) or BCG-osis (66.7%) was confirmed in all patients by positive gastric washing test (54.2%), microbial smear and culture (58.3%), or purified protein derivative (PPD) test (4.2%). The duration between BCG-osis onset and MSMD diagnosis was 21.6 months. All except three patients were initiated on second-line anti-mycobacterial agents with either a fluoroquinolone (levofloxacin: 15 mg/kg/day, ciprofloxacin: 20 mg/kg/day, ofloxacin: 15 mg/kg/day), aminoglycoside (amikacin: 10–15 mg/kg/day, streptomycin: 15 mg/kg/day), and/or macrolide (clarithromycin: 15 mg/kg/day) along with oral rifampin (10 mg/kg/day), isoniazid (15 mg/kg/day), and ethambutol (20 mg/kg/day). Three patients showed a clinical response to rifampin, despite in vitro resistance. Fourteen (58.3%) patients received also adjuvant subcutaneous IFN-γ therapy, 50 µ/m2 every other day. At the end of survey, most patients (n = 22, 91.7%) were alive and two patients died following BCG-osis and respiratory failure. Conclusions: We recommend the early instigation of second-line anti-mycobacterial agents in MSMD patients with BCG disease. [ABSTRACT FROM AUTHOR]

Clinical disease caused by the agent of tuberculosis, Mycobacterium tuberculosis , and by less virulent mycobacteria, such as bacillus Calmette-Guérin (BCG) vaccines and environmental mycobacteria, can result from inborn errors of immunity (IEIs). IEIs underlie more than 450 conditions, each associated with an impairment of the development and/or function of hematopoietic and/or non-hematopoietic cells involved in host defense. Only a minority of IEIs confer predisposition to mycobacterial disease. The IEIs underlying susceptibility to bona fide tuberculosis are less well delineated than those responsible for susceptibility to less virulent mycobacteria. However, all these IEIs share a defining feature: the impairment of immunity mediated by interferon gamma (IFN-γ). More profound IFN-γ deficiency is associated with a greater vulnerability to weakly virulent mycobacteria, whereas more selective IFN-γ deficiency is associated with a more selective predisposition to mycobacterial disease. We review here recent progress in the study of IEIs underlying mycobacterial diseases. [ABSTRACT FROM AUTHOR]

Background: Mendelian susceptibility to mycobacterial disease (MSMD) is an inborn error of immunity, resulting in susceptibility to weakly virulent mycobacteria and other intramacrophagic pathogens. Rheumatologic manifestations and vasculitis are considered rare manifestations in MSMD patients. Case presentation: In this study, we reported a 20-year-old female who was presented with recurrent lymphadenitis following bacillus Calmette-Guérin (BCG) vaccination and a history of recurrent disseminated rash diagnosed as leukocytoclastic vasculitis (LCV). A slight reduction in lymphocyte subsets including CD4+, CD19+, and CD 16 + 56 T-cell count, as well as an elevation in immunoglobulins level (IgG, IgA, IgM, IgE), were observed in the patient. Whole exome sequencing revealed a homozygous Indel-frameshift mutation, c.527_528delCT (p. S176Cfs*12), at the exon 5 of the IL12B gene. She experienced symptom resolution after treatment with anti-mycobacterial agents and subcutaneous IFN-γ. We conducted a manual literature search for MSMD patients reported with vasculitis in PubMed, Web of Science, and Scopus databases. A total of 18 MSMD patients were found to be affected by a variety of vasculitis phenotypes mainly including LCV and Henoch-Schönlein purpura (HSP) with often skin involvement. Patients were all involved with vasculitis at the median age of 6.8 (2.6–7.7) years, nearly 6.1 years after the initial presentations. Sixteen patients (88.9%) had IL12RB1 defects and concurrent Salmonella infection was reported in 15 (88.2%) patients. Conclusion: The lack of IL-12 and IL-23 signaling/activity/function and salmonella infection may be triggering factors for the development of leukocytoclastic vasculitis. IL12B or IL12RB1 deficiency and salmonellosis should be considered in MSMD patients with vasculitis. [ABSTRACT FROM AUTHOR]

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare group of genetic disorders characterized by infections with weakly virulent environmental mycobacteria (EM) or Mycobacterium bovis bacillus Calmette-Guérin (BCG). Herein, we described the case of a 4.5-year-old boy with protein-losing enteropathy, lymphoproliferation, and candidiasis, who was found to have disseminated Mycobacterium simiae infection. A homozygous mutation in the IL12B gene, c.527_528delCT (p.S176Cfs*12) was identified, responsible for the complete IL-12p40 deficiency. He was resistant to anti-mycobacterial treatment and finally died due to sepsis-related complications. [ABSTRACT FROM AUTHOR]

The natural history of tuberculosis (TB) is characterized by a large inter-individual outcome variability after exposure to Mycobacterium tuberculosis. Specifically, some highly exposed individuals remain resistant to M. tuberculosis infection, as inferred by tuberculin skin test (TST) or interferon-gamma release assays (IGRAs). We performed a genome-wide association study of resistance to M. tuberculosis infection in an endemic region of Southern Vietnam. We enrolled household contacts (HHC) of pulmonary TB cases and compared subjects who were negative for both TST and IGRA (n = 185) with infected individuals (n = 353) who were either positive for both TST and IGRA or had a diagnosis of TB. We found a genome-wide significant locus on chromosome 10q26.2 with a cluster of variants associated with strong protection against M. tuberculosis infection (OR = 0.42, 95%CI 0.35–0.49, P = 3.71×10−8, for the genotyped variant rs17155120). The locus was replicated in a French multi-ethnic HHC cohort and a familial admixed cohort from a hyper-endemic area of South Africa, with an overall OR for rs17155120 estimated at 0.50 (95%CI 0.45–0.55, P = 1.26×10−9). The variants are located in intronic regions and upstream of C10orf90, a tumor suppressor gene which encodes an ubiquitin ligase activating the transcription factor p53. In silico analysis showed that the protective alleles were associated with a decreased expression in monocytes of the nearby gene ADAM12 which could lead to an enhanced response of Th17 lymphocytes. Our results reveal a novel locus controlling resistance to M. tuberculosis infection across different populations. Author summary: There is strong epidemiological evidence that a proportion of highly exposed individuals remain resistant to M. tuberculosis infection, as shown by a negative result for Tuberculin Skin Test (TST) or IFN-γ Release Assays (IGRAs). We performed a genome-wide association study between resistant and infected individuals, which were carefully selected employing a household contact design to maximize exposure by infectious index patients. We employed stringently defined concordant results for both TST and IGRA assays to avoid misclassifications. We discovered a locus at 10q26.2 associated with resistance to M. tuberculosis infection in a Vietnamese discovery cohort. This locus could be replicated in two independent cohorts from different epidemiological settings and of diverse ancestries enrolled in France and South Africa. [ABSTRACT FROM AUTHOR]

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Autosomal recessive (AR) complete signal transducer and activator of transcription 1 (STAT1) deficiency is an extremely rare primary immunodeficiency that causes life-threatening mycobacterial and viral infections. Only seven patients from five unrelated families with this disorder have been so far reported. All causal STAT1 mutations reported are exonic and homozygous. We studied a patient with susceptibility to mycobacteria and virus infections, resulting in identification of AR complete STAT1 deficiency due to compound heterozygous mutations, both located in introns: c.128+2 T>G and c.542-8 A>G. Both mutations were the first intronic STAT1 mutations to cause AR complete STAT1 deficiency. Targeted RNA-seq documented the impairment of STAT1 mRNA expression and contributed to the identification of the intronic mutations. The patient's cells showed a lack of STAT1 expression and phosphorylation, and severe impairment of the cellular response to IFN-γ and IFN-α. The case reflects the importance of accurate clinical diagnosis and precise evaluation, to include intronic mutations, in the comprehensive genomic study when the patient lacks molecular pathogenesis. In conclusion, AR complete STAT1 deficiency can be caused by compound heterozygous and intronic mutations. Targeted RNA-seq-based systemic gene expression assay may help to increase diagnostic yield in inconclusive cases after comprehensive genomic study. [ABSTRACT FROM AUTHOR]

Interferon-γ receptor 1 (IFNγR1) deficiency is one of the inborn errors of IFN-γ immunity underlying Mendelian Susceptibility to Mycobacterial Disease (MSMD). This molecular circuit plays a crucial role in regulating the interaction between dendritic cells (DCs) and T lymphocytes, thus affecting DCs activation, maturation, and priming of T cells involved in the immune response against intracellular pathogens. We studied a girl who developed at the age of 2.5 years a Mycobacterium avium infection characterized by disseminated necrotizing granulomatous lymphadenitis, and we compared her findings with other patients with the same genetic condition. The patient carried a heterozygous 818del4 mutation in the IFNGR1 gene responsible of autosomal dominant (AD) partial IFNγR1 deficiency. During the acute infection blood cells immunophenotyping showed a marked reduction in DCs counts, including both myeloid (mDCs) and plasmacytoid (pDCs) subsets, that reversed after successful prolonged antimicrobial therapy. Histology of her abdomen lymph node revealed a profound depletion of tissue pDCs, as compared to other age-matched granulomatous lymphadenitis of mycobacterial origin. Circulating DCs depletion was also observed in another patient with AD partial IFNγR1 deficiency during mycobacterial infection. To conclude, AD partial IFNγR1 deficiency can be associated with a transient decrease in both circulating and tissular DCs during acute mycobacterial infection, suggesting that DCs counts monitoring might constitute a useful marker of treatment response. [ABSTRACT FROM AUTHOR]

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Affected patients are highly and selectively susceptible to weakly virulent mycobacteria, such as environmental mycobacteria and Bacillus Calmette–Guérin vaccines. Since 1996, disease-causing mutations have been reported in 15 genes, with allelic heterogeneity leading to 30 genetic disorders. Here, we briefly review the progress made in molecular, cellular, immunological, and clinical studies of MSMD since the last review published in 2018. Highlights include the discoveries of new genetic etiologies of MSMD: autosomal recessive (AR) complete deficiencies of (1) SPPL2a, (2) IL-12Rβ2, and (3) IL-23R, and (4) homozygosity for TYK2 P1104A, resulting in selective impairment of responses to IL-23. The penetrance of SPPL2a deficiency for MSMD is high, probably complete, whereas that of IL-12Rβ2 and IL-23R deficiencies, and TYK2 P1104A homozygosity, is incomplete, and probably low. SPPL2a deficiency has added weight to the notion that human cDC2 and Th1* cells are important for antimycobacterial immunity. Studies of IL-12Rβ2 and IL-23R deficiencies, and of homozygosity for P1104A TYK2, have shown that both IL-12 and IL-23 are required for optimal levels of IFN-γ. These recent findings illustrate how forward genetic studies of MSMD are continuing to shed light on the mechanisms of protective immunity to mycobacteria in humans. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Most patients with cDGS are not diagnosed because of recurrent or severe infections, but due to congenital heart disease or persistent hypocalcemia during the newborn period; however, severe or recurrent infections may become an important health problem a few weeks or months later, and can include opportunistic infections by viruses (e.g., cytomegalovirus), bacteria (e.g., I Pseudomona aeruginosa i ), or fungi (e.g., I Pneumocystis jirovecii i ) [[2]]. Despite their predisposition to severe infections, mycobacteria rarely affect patients with cDGS and only a few cases have been reported in the literature to date [[3]]. MSMD encompass rare clinical conditions characterized by predisposition to infection by weakly virulent mycobacteria, like bacillus Calmette-Guérin (BCG), and non-tuberculous environmental mycobacteria in otherwise healthy individuals [[5]]. [Extracted from the article]

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN‐γ immunity. Since 1996, disease‐causing mutations have been found in 11 genes, which, through allelic heterogeneity, underlie 21 different genetic disorders. We briefly review here progress in the study of molecular, cellular and clinical aspects of MSMD since the last comprehensive review published in 2014. Highlights include the discoveries of (1) a new genetic etiology, autosomal recessive signal peptide peptidase‐like 2 A deficiency, (2) TYK2‐deficient patients with a clinical phenotype of MSMD, (3) an allelic form of partial recessive IFN‐γR2 deficiency, and (4) two forms of syndromic MSMD: RORγ/RORγT and JAK1 deficiencies. These recent findings illustrate how genetic and immunological studies of MSMD can shed a unique light onto the mechanisms of protective immunity to mycobacteria in humans. [ABSTRACT FROM AUTHOR]

Purpose: Mendelian susceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency, triggered by non-tuberculous mycobacteria or Bacillus Calmette-Guérin (BCG) vaccines and characterized by severe diseases. All known genetic etiologies are inborn errors of IFN-γ-mediated immunity. Here, we report the molecular, cellular, and clinical features of patients from 15 Iranian families with disseminated disease without vaccination (2 patients) or following live BCG vaccination (14 patients). Methods: We used whole blood samples from 16 patients and 12 age-matched healthy controls. To measure IL-12 and IFN-γ, samples were activated by BCG plus recombinant human IFN-γ or recombinant human IL-12. Immunological assessments and genetic analysis were also done for the patients. Results: Eight patients affected as a result of parental first-cousin marriages. Seven patients originated from multiplex kindred with positive history of death because of tuberculosis or finding the MSMD-related gene mutations. Two patients died due to mycobacterial disease at the ages of 8 months and 3.7 years. The remaining patients were alive at the last follow-up and were aged between 2 and 13 years. Patients suffered from infections including chronic mucocutaneous candidiasis (n = 10), salmonellosis (n = 2), and Leishmania (responsible for visceral form) (n = 2). Thirteen patients presented with autosomal recessive (AR) IL-12Rβ1 deficiency, meaning their cells produced low levels of IFN-γ. Bi-allelic IL12RB1 mutations were detected in nine of patients. Three patients with AR IL-12p40 deficiency (bi-allelic IL12B mutations) produced low levels of both IL-12 and IFN-γ. Overall, we found five mutations in the IL12RB1 gene and three mutations in the IL12B gene. Except one mutation in exon 5 (c.510C>A) of IL12B, all others were previously reported to be loss-of-function mutations. Conclusions: We found low levels of IFN-γ production and failure to respond to IL12 in 13 Iranian MSMD patients. Due to complicated clinical manifestations in affected children, early cellular and molecular diagnostics is crucial in susceptible patients. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: Mendelian suceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency predisposing to severe disease caused by mycobacteria and other intracellular pathogens. Delay in diagnosis can have an impact on the patient’s prognosis.Methods: We evaluated the IFN-γ circuit by studying IFN-γ production after mycobacterial challenge as well as IL-12Rβ1 expression and STAT4 phosphorylation in response to IL-12p70 stimulation in whole blood of a 6-year-old Peruvian girl with disseminated recurrent mycobacterial infection diagnosed as multidrug-resistant tuberculosis. Genetic studies with Sanger sequencing were used to identify the causative mutation. Microbiological studies based on PCR reactions were used to diagnose the specific mycobacterial species.Results: We identified a homozygous mutation in the IL12RB1 gene (p. Arg211*) causing abolished expression of IL-12Rβ1 and IL-12 response. MSMD diagnosis led to a microbiological reevaluation of the patient, revealing a BCG vaccine-related infection instead of tuberculosis. Treatment was then adjusted, with good response.Conclusions: We report the first Peruvian patient with IL-12Rβ1 deficiency. Specific mycobacterial species diagnosis within Mycobacterium tuberculosis complex is still challenging in countries with limited access to PCR-based microbiological diagnostic techniques. Awareness of MSMD warning signs and accurate microbiological diagnosis of mycobacterial infections are of the utmost importance for optimal diagnosis and management of affected patients. [ABSTRACT FROM AUTHOR]

Mendelian susceptibility to mycobacterial disease is a rare syndrome characterized by severe clinical infections usually caused by weakly virulent mycobacterial species such as Bacillus Calmette-Guérin vaccines and environmental nontuberculous mycobacteria or more virulent mycobacteria as mycobacterium tuberculosis. Since 1996, 9 genes including 7 autosomal (STAT1, IFNGR1, IFNGR2, IL12B, IL12RB1, ISG15, and IRF8) and 2 X-linked genes (NEMO and CYBB) have been identified. Allelic heterogeneity leaded to recognize about 18 genetic diseases with variable clinical phenotypes, but sharing a same physiological mechanism represented by a defect in human IL-12-dependant-INF-g-mediated immunity. We report here a case of multifocal Bacillus Calmette-Gue'rin osteomyelitis in a context Mendelian susceptibility to mycobacterial disease mimicking a metastatic neuroblastoma in a child presenting with delayed growth. The investigation of her twin sister showed the same disease. A heterozygous mutation in exon 22 of STAT1 gene was found in both sisters, another sister and the father being healthy and heterozygous for the same mutation. [ABSTRACT FROM AUTHOR]

In this report, we have described a child suffering from Mendelian susceptibility to mycobacterial disease (MSMD) owing to an autosomal recessive, complete T-bet deficiency, which impairs IFN-γ production by innate and innate-like adaptive, but not mycobacterial-reactive purely adaptive lymphocytes. In this study, we explored the persistent upper airway inflammation (UAI) and blood eosinophilia in this patient. Unlike the wild-type (WT) T-bet, the mutant form of T-bet from this patient did not inhibit the production of T helper 2 (Th2) cytokines, including IL-4, IL-5, IL-9, and IL-13, when overexpressed in Th2 cells. Moreover, Herpesvirus saimiri immortalized T cells from the patient produced abnormally large amounts of Th2 cytokines, and the patient had markedly high plasma IL-5 and IL-13 concentrations. Finally, the patient's CD4+ αβ T cells produced most of the Th2 cytokines in response to chronic stimulation, regardless of their antigen specificities, a phenotype reversed by the expression of WT T-bet. T-bet deficiency thus underlies the excessive production of Th2 cytokines, particularly IL-5 and IL-13, by CD4+ αβ T cells, causing blood eosinophilia and UAI. The MSMD of this patient results from defective IFN-γ production by innate and innate-like adaptive lymphocytes, whereas the UAI and eosinophilia result from excessive Th2 cytokine production by adaptive CD4+ αβ T lymphocytes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Mycobacterium tilburgii rarely causes disseminated disease. We describe a case of M. tilburgii infection in an otherwise healthy 33-year-old woman, who was found to carry bi-allelic mutations of the gene encoding the β1 chain of the IL-12 receptor. [ABSTRACT FROM AUTHOR]

We report identical twins with intellectual disability, progressive spastic paraplegia and short stature, born to a consanguineous family. Intriguingly, both children presented with lymphadenitis caused by the live Bacillus Calmette-Guérin (BCG) vaccine. Two syndromes – hereditary spastic paraplegia (HSP) and mycobacterial disease – thus occurred simultaneously. Whole-exome sequencing (WES) revealed a homozygous nonsense mutation (p.R1105X) of the AP4E1 gene, which was confirmed by Sanger sequencing. The p.R1105X mutation has no effect on AP4E1 mRNA levels, but results in lower levels of AP-4ε protein and of the other components of the AP-4 complex, as shown by western blotting, immunoprecipitation and immunofluorescence. Thus, the C-terminal part of the AP-4ε subunit plays an important role in maintaining the integrity of the AP-4 complex. No abnormalities of the IL-12/IFN-γ axis or oxidative burst pathways were identified. In conclusion, we identified twins with autosomal recessive AP-4 deficiency associated with HSP and mycobacterial disease, suggesting that AP-4 may play important role in the neurological and immunological systems. [ABSTRACT FROM AUTHOR]

Background: Tuberculosis remains a major health problem in developing countries especially with the emergence of multidrug resistant strains. Mendelian Susceptibility to Mycobacterial Disease (MSMD) is a rare disorder with impaired immunity against mycobacterial pathogens. Reported MSMD etiologies highlight the crucial role of the Interferon gamma /Interleukin 12 (IFN-γ/ IL-12) axis and the phagocyte respiratory burst axis. Purpose: Screen patients with possible presentations for MSMD. Methods: Patients with disseminated BCG infection following vaccination, atypical mycobacterial infections or recurrent tuberculosis infections were recruited from the Primary Immune Deficiency Clinic at Cairo University Specialized Pediatric Hospital, Egypt and immune and genetic laboratory investigations were conducted at Human Genetic of Infectious Diseases laboratory in Necker Medical School, France from 2005-2009. IFN-γ level in patient's plasma as well as mutations in the eight previously identified MSMD-causing genes were explored. Results: Nine cases from eight (unrelated) kindreds were evaluated in detail. We detected a high level of IFN-γ in plasma in one patient. Through Sanger sequencing, a homozygous mutation in the IFNGR1 gene at position 485 corresponding to an amino acid change from serine to phenylalanine (S485F), was detected in this patient. Conclusion: We report the first identified case of MSMD among Egyptian patients, including in particular a new IFNGR1 mutation underlying IFN-γR1 deficiency. The eight remaining patients need to be explored further. These findings have implications regarding the compulsory Bacillus Calmette Guerin vaccination policy in Egypt, especially given the high consanguinity rate. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction Genome-wide homozygosity mapping is a powerful method for locating rare recessive Mendelian mutations. However, statistical power decreases dramatically in the presence of genetic heterogeneity. Methods The authors applied an empirical approach to test for linkage accounting for genetic heterogeneity by calculating the sum of positive per-family multipoint LOD scores (S) across all positions, and obtaining corresponding empirical p values (EmpP) through permutations. Results The statistical power of the approach was found to be consistently higher than the classical heterogeneity LOD by simulations. Among 21 first-cousin matings with a single affected child, for five families linked to a locus of interest and 16 families to other loci, S/EmpP achieved a power of 40% versus 28% for heterogeneity LOD at an α level of 0.001. The mean size of peak linkage regions was markedly higher for true loci than false positive regions. The S/EmpP approach was applied to a sample of 17 consanguineous families with Mendelian susceptibility to mycobacterial disease, leading to the identification of two mutations in IL12RB1 and TYK2 from the largest of six linkage regions at p<10-3. Conclusions The S/EmpP approach is a flexible and powerful approach that can be applied to linkage analysis of families with suspected Mendelian disorders. [ABSTRACT FROM AUTHOR]

Germline mutations in CYBB, the human gene encoding the gp91phox subunit of the phagocyte NADPH oxidase, impair the respiratory burst of all types of phagocytes and result in X-linked chronic granulomatous disease (CGD). We report here two kindreds in which otherwise healthy male adults developed X-linked recessive Mendelian susceptibility to mycobacterial disease (MSMD) syndromes. These patients had previously unknown mutations in CYBB that resulted in an impaired respiratory burst in monocyte-derived macrophages but not in monocytes or granulocytes. The macrophage-specific functional consequences of the germline mutation resulted from cell-specific impairment in the assembly of the NADPH oxidase. This 'experiment of nature' indicates that CYBB is associated with MSMD and demonstrates that the respiratory burst in human macrophages is a crucial mechanism for protective immunity to tuberculous mycobacteria. [ABSTRACT FROM AUTHOR]

The article discusses the case of a 50-year-old woman who was diagnosed with nontuberculous mycobacteria (NTM) infection and treated due to the detection of the interferon-y (IFN-y) autoantibodies. Topics discussed include her pathological examination that revealed a nonnecrotizing granuloma, the continued use of the antimycobacterial treatment and changed to azithromycin suppressive therapy and a reviewed literature for the other cases of IFN-y antibody-related NTM infection.

A few known primary immunodeficiencies confer predisposition to clinical disease caused by weakly virulent mycobacteria, such as BCG vaccines (regional disease, known as BCG-itis, or disseminated disease, known as BCG-osis), or more virulent mycobacteria, such as Mycobacterium tuberculosis (pulmonary and disseminated tuberculosis). We investigated the clinical and genetic features of a 12-year-old boy with both recurrent BCG-osis and disseminated tuberculosis. The patient''s phagocytic cells produced no O2 −. A hemizygous splice mutation was found in intron 5 of CYBB, leading to a diagnosis of X-linked chronic granulomatous disease. Chronic granulomatous disease should be suspected in all children with BCG-osis, even in the absence of nonmycobacterial infectious diseases, and in selected children with recurrent BCG-itis or severe tuberculosis. [Copyright &y& Elsevier]

Interleukin 12-23 deficiency in the interferon gamma pathway in a 6-month-old toddler who has BCG vaccine complications Bacillus Calmette-Guérin (BCG) is a form of I Mycobacterium bovis i that possesses all the structural features of tuberculosis bacillus, but its ability to cause disease has been eliminated is a viable vaccine with low virulence.1-3 A 6-month-old toddler was admitted to the department of pediatric infectious diseases with complaints of swelling under the left axilla. The patient was investigated for the suspicion of Mendel susceptibility (MSMD) to mycobacterial diseases, and it was later found that the patient was the homozygous carrier of the mutation leading to IFNgR1 deficiency. [Extracted from the article]

The transcription factor signal transducer and activator of transcription-1 (STAT1) plays a key role in immunity against mycobacterial and viral infections. Here, we characterize three human STAT1 germline alleles from otherwise healthy patients with mycobacterial disease. The previously reported L706S, like the novel Q463H and E320Q alleles, are intrinsically deleterious for both interferon gamma (IFNG)-induced gamma-activating factor-mediated immunity and interferon alpha (IFNA)-induced interferon-stimulated genes factor 3-mediated immunity, as shown in STAT1-deficient cells transfected with the corresponding alleles. Their phenotypic effects are however mediated by different molecular mechanisms, L706S affecting STAT1 phosphorylation and Q463H and E320Q affecting STAT1 DNA-binding activity. Heterozygous patients display specifically impaired IFNG-induced gamma-activating factor-mediated immunity, resulting in susceptibility to mycobacteria. Indeed, IFNA-induced interferon-stimulated genes factor 3-mediated immunity is not affected, and these patients are not particularly susceptible to viral disease, unlike patients homozygous for other, equally deleterious STAT1 mutations recessive for both phenotypes. The three STAT1 alleles are therefore dominant for IFNG-mediated antimycobacterial immunity but recessive for IFNA-mediated antiviral immunity at the cellular and clinical levels. These STAT1 alleles define two forms of dominant STAT1 deficiency, depending on whether the mutations impair STAT1 phosphorylation or DNA binding. [ABSTRACT FROM AUTHOR]

Germline mutations in five autosomal genes involved in interleukin (IL)-12-dependent, interferon (IFN)-γ-mediated immunity cause Mendelian susceptibility to mycobacterial diseases (MSMD). The molecular basis of X-linked recessive (XR)-MSMD remains unknown. We report here mutations in the leu cine zipper (LZ) domain of the NF-κB essential modulator (NEMO) gene in three unrelated kindreds with XR-MSMD. The mutant proteins were produced in normal amounts in blood and fibroblastic cells. However, the patients' monocytes presented an intrinsic defect in T cell-dependent IL-12 production, resulting in defective IFN-γ, secretion by T cells. IL-12 production was also impaired as the result of a specific defect in NEMO- and NF-κB/c-Rel-mediated CD40 signaling after the stimulation of monocytes and dendritic cells by CD40L-expressing T cells and fibroblasts, respectively. However, the CD40-dependent up-regulation of costimulatory molecules of dendritic cells and the proliferation and immunoglobulin class switch of B cells were normal. Moreover, the patients' blood and fibroblastic cells responded to other NF-KB activators, such as tumor necrosis factor-α, IL-1β, and lipopolysaccharide. These two mutations in the NEMO 17 domain provide the first genetic etiology of XR-MSMD. They also demonstrate the importance of the T cell- and CD40L-triggered, CD40-, and NEMO/NF-κB/c-Rel-mediated induction of IL-12 by monocyte-derived cells for protective immunity to mycobacteria in humans. [ABSTRACT FROM AUTHOR]

Disseminated BCG infection is a rare complication of vaccination that occurs in patients with impaired immunity. In recent years, a series of inherited disorders of the IL-12-IFN-γ axis have been described that predispose affected individuals to disseminated disease caused by BCG, environmental Mycobacteria, and non-typhoidal Salmonella. The routine immunological work-up of these patients is normal and the diagnosis requires specific investigation of the IL-12-IFN-γ circuit. We report here the first two such patients originating from and living in Iran. The first child is two years old and suffers from complete IFN-γ receptor 2 deficiency and disseminated BCG infection. He is currently in clinical remission thanks to prolonged multiple antibiotic therapy. The other, a 28-year-old adult, suffers from IL-12p40 deficiency and presented with disseminated BCG infection followed by recurrent episodes of systemic salmonellosis. He is now doing well. A third patient of Iranian descent, living in North America, was reported elsewhere to suffer from IL-12Rβ1 deficiency. These three patients thus indicate that various inherited defects of the IL-12-IFN-γ circuit can be found in Iranian people. In conclusion we recommend to consider the disorders of the IL-12-IFN-γ circuit in all patients with severe BCG infection, disseminated environmental mycobacterial disease, or systemic non-typhoidal salmonellosis, regardless of their ethnic origin and country of residence. [ABSTRACT FROM AUTHOR]

Mutations involving gains of glycosylation have been considered rare, and the pathogenic role of the new carbohydrate chains has never been formally established. We identified three children with mendelian susceptibility to mycobacterial disease who were homozygous with respect to a missense mutation in IFNGR2 creating a new N-glycosylation site in the IFNγR2 chain. The resulting additional carbohydrate moiety was both necessary and sufficient to abolish the cellular response to IFNγ. We then searched the Human Gene Mutation Database for potential gain-of-N-glycosylation missense mutations; of 10,047 mutations in 577 genes encoding proteins trafficked through the secretory pathway, we identified 142 candidate mutations (∼1.4%) in 77 genes (∼13.3%). Six mutant proteins bore new N-linked carbohydrate moieties. Thus, an unexpectedly high proportion of mutations that cause human genetic disease might lead to the creation of new N-glycosylation sites. Their pathogenic effects may be a direct consequence of the addition of N-linked carbohydrate. [ABSTRACT FROM AUTHOR]

Interferon-stimulated gene 15 (ISG15) was the first ubiquitin-like modifier protein identified that acts by protein conjugation (ISGylation) and is thought to modulate IFN-induced inflammation. Here, we report a new patient from a non-consanguineous Argentinian family, who was followed for recurrent ulcerative skin lesions, cerebral calcifications and lung disease. Whole Exome Sequencing (WES) revealed two novel compound heterozygous variants (c.285del and c.299_312del, NM_005101.4 GRCh37(hg19), both classified as pathogenic according to ACMG criteria) in the ISG15 gene, resulting in a complete deficiency due to disruption of the second ubiquitin domain of the corresponding protein. The clinical phenotype of this patient is unique given the presence of recurrent pulmonary manifestations and the absence of mycobacterial infections, thus resulting in a phenotype distinct from that previously described in patients with biallelic loss-of-function (LOF) ISG15 variants. This case highlights the role of ISG15 as an immunomodulating factor whose LOF variants result in heterogeneous clinical presentations. [ABSTRACT FROM AUTHOR]

Interferon γ (IFN-γ) was shown to be a macrophage activating factor already in 1984. Consistently, inborn errors of IFN-γ immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD). MSMD is characterized by genetic predisposition to disease caused by weakly virulent mycobacterial species. Paradoxically, macrophages from patients with MSMD were little tested. Here, we report a disease modeling platform for studying IFN-γ related pathologies using macrophages derived from patient specific induced pluripotent stem cells (iPSCs). We used iPSCs from patients with autosomal recessive complete- and partial IFN-γR2 deficiency, partial IFN-γR1 deficiency and complete STAT1 deficiency. Macrophages from all patient iPSCs showed normal morphology and IFN-γ-independent functionality like phagocytic uptake of bioparticles and internalization of cytokines. For the IFN-γ-dependent functionalities, we observed that the deficiencies played out at various stages of the IFN-γ pathway, with the complete IFN-γR2 and complete STAT1 deficient cells showing the most severe phenotypes, in terms of upregulation of surface markers and induction of downstream targets. Although iPSC-derived macrophages with partial IFN-γR1 and IFN-γR2 deficiency still showed residual induction of downstream targets, they did not reduce the mycobacterial growth when challenged with Bacillus Calmette–Guérin. Taken together, we report a disease modeling platform to study the role of macrophages in patients with inborn errors of IFN-γ immunity. [ABSTRACT FROM AUTHOR]

Mendelian susceptibility to mycobacterial disease is a rare primary immunodeficiency characterized by severe infections caused by weakly virulent mycobacteria. Biallelic null mutations in genes encoding interferon gamma receptor 1 or 2 (IFNGR1 or IFNGR2) result in a life-threatening disease phenotype in early childhood. Recombinant interferon γ (IFN-g) therapy is inefficient, and hematopoietic stem cell transplantation has a poor prognosis. Thus, we developed a hematopoietic stem cell (HSC) gene therapy approach using lentiviral vectors that express Ifngr1 either constitutively or myeloid specifically. Transduction of mouse Ifngr1-/- HSCs led to stable IFNgR1 expression on macrophages, which rescued their cellular responses to IFN-g. As a consequence, genetically corrected HSC-derived macrophages were able to suppress T-cell activation and showed restored antimycobacterial activity against Mycobacterium avium and Mycobacterium bovis Bacille Calmette-Gue' rin (BCG) in vitro. Transplantation of genetically corrected HSCs into Ifngr12/2 mice before BCG infection prevented manifestations of severe BCG disease and maintained lung and spleen organ integrity, which was accompanied by a reduced mycobacterial burden in lung and spleen and a prolonged overall survival in animals that received a transplant. In summary, we demonstrate an HSC-based gene therapy approach for IFNgR1 deficiency, which protects mice from severe mycobacterial infections, thereby laying the foundation for a new therapeutic intervention in corresponding human patients. [ABSTRACT FROM AUTHOR]

Inborn errors of immunity (IEI) delineate redundant and essential defense mechanisms in humans. We review 15 autosomal-dominant (AD) or -recessive (AR) IEI involving 11 transcription factors (TFs) and impairing interferon-gamma (IFN-γ) immunity, conferring a predisposition to mycobacterial diseases. We consider three mechanism-based categories: 1) IEI mainly affecting myeloid compartment development (AD GATA2 and AR and AD IRF8 deficiencies), 2) IEI mainly affecting lymphoid compartment development (AR FOXN1, AR PAX1, AR RORγ/RORγT, AR T-bet, AR c-Rel, AD STAT3 gain-of-function (GOF), and loss-of-function (LOF) deficiencies), and 3) IEI mainly affecting myeloid and/or lymphoid function (AR and AD STAT1 LOF, AD STAT1 GOF, AR IRF1, and AD NFKB1 deficiencies). We discuss the contribution of the discovery and study of inborn errors of TFs essential for host defense against mycobacteria to molecular and cellular analyses of human IFN-γ immunity. [Display omitted] • Distinct stages of antimycobacterial IFN-γ immunity revealed by studies of IEI of TFs. • Interleukin (IL)-12 and IL-23, produced by myeloid cells, enhance IFN-γ production. • IFN-γ, produced by lymphocytes, enhances mycobacterial killing in phagocytes. [ABSTRACT FROM AUTHOR]

Abstract: The vast majority of primary immunodeficiencies (PIDs) predispose affected individuals to recurrent or chronic infectious diseases, because they affect protective immunity to both primary and secondary or latent infections. We discuss here three recently described groups of PIDs that seem to impair immunity to primary infections without compromising immunity to secondary and latent infections. Patients with mutations in IL12B or IL12RB1 typically present mycobacterial disease in childhood with a favorable progression thereafter. Cross-protection between mycobacterial infections has even been observed. Patients with mutations in IRAK4 or MYD88 suffer from pyogenic bacterial diseases, including invasive pneumococcal diseases in particular. These diseases often recur, although not always with the same serotype, but the frequency of these recurrences tails off, with no further infections observed from adolescence onwards. Finally, mutations in UNC93B1 and TLR3 are associated with childhood herpes simplex encephalitis, which strikes only once in most patients, with almost no recorded cases of more than two bouts of this disease. Unlike infections in patients with other PIDs, the clinical course of which typically deteriorates with age even if appropriate treatment is given, the prognosis of patients with these three newly described PIDs tends to improve spontaneously with age, provided, of course, that the initial infection is properly managed. In other words, although life-threatening in early childhood, these new PIDs are associated with a favorable outcome in adulthood. They provide proof-of-principle that infectious diseases of childhood striking only once may result from single-gene inborn errors of immunity. [Copyright &y& Elsevier]