IFN-γR1 Deficiency Research Articles

Myeloid interferon-γ receptor deficiency does not affect atherosclerosis in LDLR-/- mice

Background and aimsAtherosclerosis is a chronic lipid-driven inflammatory disease of the arterial wall. Interferon gamma (IFNγ) is an important immunomodulatory cytokine and a known pro-atherosclerotic mediator. However, cell-specific targeting of IFNγ or its signaling in atherosclerosis development has not been studied yet. As macrophages are important IFNγ targets, we here addressed the involvement of myeloid IFNγ signaling in murine atherosclerosis. MethodsBone marrow was isolated from interferon gamma receptor 2 chain (IFNγR2) wildtype and myeloid IFNγR2 deficient mice and injected into lethally irradiated LDLR-/- mice. After recovery mice were put on a high fat diet for 10 weeks after which atherosclerotic lesion analysis was performed. In addition, the accompanying liver inflammation was assessed. ResultsEven though absence of myeloid IFNγ signaling attenuated the myeloid IFNγ response, no significant differences in atherosclerotic lesion size or phenotype were found. Also, when examining the liver inflammatory state no effects of IFNγR2 deficiency could be observed. ConclusionOverall, our data argue against a role for myeloid IFNγR2 in atherosclerosis development. Since myeloid IFNγ signaling seems to be nonessential throughout atherogenesis, it is important to understand the mechanisms by which IFNγ acts in atherogenesis. In the future new studies should be performed considering other cell-specific targets.

Phagocyte nicotinamide adenine dinucleotide phosphate oxidase activity in patients with inherited IFN-γR1 or IFN-γR2 deficiency

An understanding of protective immunity to mycobacterial infection is critical for the development of effective strategies to control tuberculosis (TB), a major public health problem worldwide. Mendelian susceptibility to mycobacterial disease (MSMD) is a rare condition characterized by clinical disease caused by weakly virulent mycobacteria, such as Mycobacterium bovis Bacille Calmette-Guérin (BCG) vaccines and nontuberculous, environmental mycobacteria (OMIM209950).1 Patients are also susceptible to M tuberculosis.

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

Osteomyelitis due to Mycobacterium bovis Bacille Calmette-Guerin (BCG) often develops in patients with interferon-γ receptor 1 (IFNγR1) deficiency. In these patients, susceptibility appears to be caused by impaired interleukin-12- and IFNγ-mediated immunity. Here we report the case of a one-year-old girl with dominant partial IFNγR1 deficiency who suffered from lymphadenitis and multiple sites of osteomyelitis due to BCG infection. She was allergic to isoniazid and rifampicin--the prescribed standard treatment--and required prior desensitization therapy. She was subsequently treated with these drugs, but her symptoms did not improve. IFNγ therapy was added to the antitubercular therapy, increasing the serum level of IFNγ and leading to the resolution of the lymphadenitis and osteomyelitis. In conclusion, high dose IFNγ therapy in combination with antitubercular drugs led to resolution of BCG infection in a patient with dominant partial IFNγ deficiency.

Partial IFN-γR2 deficiency is due to protein misfolding and can be rescued by inhibitors of glycosylation

AbstractWe report a molecular study of the two known patients with autosomal recessive, partial interferon-γ receptor (IFN-γR)2 deficiency (homozygous for mutations R114C and G227R), and three novel, unrelated children, homozygous for S124F (P1) and G141R (P2 and P3). IFN-γR2 levels on the surface of the three latter patients' cells are slightly lower than those on control cells. The patients' cells also display impaired, but not abolished, response to IFN-γ. Moreover, the R114C, S124F, G141R and G227R IFNGR2 hypomorphic alleles all encode misfolded proteins with abnormal N-glycosylation. The mutants are largely retained in the endoplasmic reticulum, although a small proportion reach and function at the cell surface. Strikingly, the IFN-γ response of the patients' cells is enhanced by chemical modifiers of N-glycosylation, as previously shown for patients with gain-of-glysosylation T168N and misfolding 382-387dup null mutations. All four in-frame IFNGR2 hypomorphic mutant alleles encoding surface-expressed receptors are thus deleterious by a mechanism involving abnormal N-glycosylation and misfolding of the IFN-γR2 protein. The diagnosis of partial IFN-γR2 deficiency is clinically useful, as affected patients should be treated with IFN-, unlike patients with complete IFN-γR2 deficiency. Moreover, inhibitors of glycosylation might be beneficial in patients with complete or partial IFN-γR2 deficiency due to misfolding or gain-of-glycosylation receptors.

Heterozygosity for the Y701C STAT1 mutation in a multiplex kindred with multifocal osteomyelitis

Heterozygosity for dominant-negative STAT1 mutations underlies autosomal dominant Mendelian susceptibility to mycobacterial diseases. Mutations conferring Mendelian susceptibility to mycobacterial diseases have been identified in the regions of the STAT1 gene encoding the tail segment, DNA-binding domain and SH2 domain. We describe here a new heterozygous mutation, Y701C, in a Japanese two-generation multiplex kindred with autosomal dominant Mendelian susceptibility to mycobacterial diseases. This mutation affects precisely the canonical STAT1 tyrosine phosphorylation site. The Y701C STAT1 protein is produced normally, but its phosphorylation is abolished, resulting in a loss-of-function for STAT1-dependent cellular responses to interferon-γ or interferon-α. In the patients' cells, the allele is dominant-negative for γ-activated factor-mediated responses to interferon-γ, but not for interferon-stimulated gene factor-3-mediated responses to interferon-α/β, accounting for the clinical phenotype of Mendelian susceptibility to mycobacterial diseases without severe viral diseases. Interestingly, both patients displayed multifocal osteomyelitis, which is often seen in patients with Mendelian susceptibility to mycobacterial diseases with autosomal dominant partial IFN-γR1 deficiency. Multifocal osteomyelitis should thus prompt investigations of both STAT1 and IFN-γR1. This experiment of nature also confirms the essential role of tyrosine 701 in human STAT1 activity in natura.

Haploinsufficiency at the human IFNGR2 locus contributes to mycobacterial disease

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare syndrome, the known genetic etiologies of which impair the production of, or the response to interferon-gamma (IFN-γ). We report here a patient (P1) with MSMD whose cells display mildly impaired responses to IFN-γ, at levels, however, similar to those from MSMD patients with autosomal recessive (AR) partial IFN-γR2 or STAT1 deficiency. Whole-exome sequencing (WES) and Sanger sequencing revealed only one candidate variation for both MSMD-causing and IFN-γ-related genes. P1 carried a heterozygous frame-shift IFNGR2 mutation inherited from her father. We show that the mutant allele is intrinsically loss-of-function and not dominant-negative, suggesting haploinsufficiency at the IFNGR2 locus. We also show that Epstein-Barr virus transformed B lymphocyte cells from 10 heterozygous relatives of patients with AR complete IFN-γR2 deficiency respond poorly to IFN-γ, in some cases as poorly as the cells of P1. Naive CD4(+) T cells and memory IL-4-producing T cells from these individuals also responded poorly to IFN-γ, whereas monocytes and monocyte-derived macrophages (MDMs) did not. This is consistent with the lower levels of expression of IFN-γR2 in lymphoid than in myeloid cells. Overall, MSMD in this patient is probably due to autosomal dominant (AD) IFN-γR2 deficiency, resulting from haploinsufficiency, at least in lymphoid cells. The clinical penetrance of AD IFN-γR2 deficiency is incomplete, possibly due, at least partly, to the variability of cellular responses to IFN-γ in these individuals.

Granulomatous Skin Lesions, Severe Scrotal and Lower Limb Edema Due to Mycobacterial Infections in a Child with Complete IFN-γ Receptor-1 Deficiency

Interferon-γ receptor-1 (IFNγR1) deficiency is caused by mutations in the IFNγR1 gene and is characterized mainly by susceptibility to mycobacterial disease. Herein, we report an 8-month-old boy with complete recessive IFNγR1 deficiency, afflicted by recurrent mycobacterial diseases with Mycobacterium bovis, Mycobacterium tuberculosis, Mycobacterium avium intracellulare and Mycobacterium fortuitum. Genetic analysis showed a homozygous mutation (106insT) in the IFNγR1 gene leading to complete IFNγR1 deficiency. In addition, he had atypical mycobacterial skin lesions caused by M. avium intracellulare and developed scrotal and lower limb lymphedema secondary to compression of large and fixed inguinal lymphadenopathies. Hematopoietic stem cell transplantation was performed from a matched unrelated donor at 5 years of age; however, he died at 9 months post-transplant. To our knowledge, the patient is the first case with IL-12/IFN-γ pathway defect and severe lymphedema. We have also reviewed and summarized the literature related with IFNγR1 deficiency.

Severe disseminated mycobacterial infection in a boy with a novel mutation leading to IFN-γR2 deficiency

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare syndrome characterized by predisposition to severe, sometimes lethal, disease caused by otherwise poorly virulent mycobacteria. We report here a boy with a recurrent mycobacterial infection from the age of five months. Immunological analyses revealed an inability to respond to IFN-γ, subsequent genetic analyses revealed a novel homozygous mutation, r.679G>A in the IFNGR2 gene, resulting in a G227R substitution, that caused IFN-γR2 deficiency. This is only the 8th mutation in IFN-γR2 known so far. The boy eventually died of hepatic coma due to liver failure at the age of five.

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.

Multiple cutaneous squamous cell carcinomas in a patient with interferon γ receptor 2 (IFNγR2) deficiency

Disseminated squamous cell carcinoma (SCC) of the skin is exceedingly rare in children. SCC occurs after immunodeficiency from immunosuppression in organ transplant recipients or patients with HIV infection or leukaemia,...

Functional analysis of naturally occurring amino acid substitutions in human IFN-γR1

IFN-γ plays an essential role in the IL-12/IL-23/IFN-γ pathway that is required for the defense against intracellular pathogens. In the IFN-γR1 several amino acid substitutions have been reported that abrogate IFN-γ signaling. These substitutions can lead to a null phenotype and enhanced susceptibility to infection by poorly pathogenic mycobacteria, a disorder known as Mendelian Susceptibility to Mycobacterial Disease (MSMD). More common amino acid variations in the IFN-γR1 may also influence IFN-γR function, albeit more subtle. To determine the effect of various amino acid substitutions on IFN-γR1 expression and function we cloned two newly identified amino acid substitutions (S149L, I352M), four common variations (V14M, V61I, H335P, L467P), seven reported missense mutations (V61Q, V63G, Y66C, C77Y, C77F, C85Y, I87T) and the 818delTTAA mutation in a retroviral expression vector. IFN-γR1 expression was determined as well as responsiveness to IFN-γ stimulation. The two newly discovered variants, and the four common polymorphisms could be detected on the cell surface, however, the V14M, H335P and I352M variants were significantly lower expressed at the cell membrane, compared to the wild type receptor. Despite the variance in cell surface expression, these IFN-γR1 variants did not affect function. In contrast to literature, in our model the expression of the V63G variant was severely reduced and its function was severely impaired but not completely abrogated. In addition, we confirmed the severely reduced function of the I87T mutant receptor, the completely abrogated expression and function of the V61E, V61Q, C77F, C77Y and the C85Y mutations, as well as the overexpression pattern of the 818delTTAA mutant receptor. The Y66C mutation was expressed at the cell surface, it was however, not functional. We conclude that the V14M, V61I, S149L, H335P, I352M and L467P are functional polymorphisms. The other variants are deleterious mutations with V61E, V61Q, Y66C, C77F, C77Y and C85Y leading to complete IFN-γR1 deficiency, while V63G and I87T lead to partial IFN-γR1 deficiency.

A novel form of cell type-specific partial IFN-γR1 deficiency caused by a germ line mutation of the IFNGR1 initiation codon

IFN-gammaR1 deficiency is a genetic etiology of Mendelian susceptibility to mycobacterial diseases, and includes two forms of complete recessive deficiency, with or without cell surface expression, and two forms of partial deficiency, dominant or recessive. We report here a novel form of partial and recessive Interferon gamma receptor 1 (IFN-gammaR1) deficiency, which is almost as severe as complete deficiency. The patient is homozygous for a mutation of the initiation codon (M1K). No detectable expression and function of IFN-gammaR1 were found in the patient's fibroblasts. However, IFN-gammaR1 expression was found to be impaired, but not abolished, on the EBV-transformed B cells, which could respond weakly to IFN-gamma. The mechanism underlying this weak expression involves leaky translation initiation at both non-AUG codons and the third AUG codon at position 19. It results in the residual expression of IFN-gammaR1 protein of normal molecular weight and function. The residual IFN-gamma signaling documented in this novel form of partial IFN-gammaR1 deficiency was not ubiquitous and was milder than that seen in other forms of partial IFN-gammaR1 deficiency, accounting for the more severe clinical phenotype of the patient, which was almost as severe as that of patients with complete deficiency.

Revisiting human primary immunodeficiencies

Human primary immunodeficiencies (PIDs) are often thought to be confined to a few rare, familial, monogenic, recessive traits impairing the development or function of one or several leucocyte subsets and resulting in multiple, recurrent, opportunistic and fatal infections in infancy. We highlight here the rapidly growing number of exceptions to each of these conventional qualifications. Indeed, bona fide PIDs include common and sporadic illnesses and may present as dominant, or even polygenic traits; their pathogenesis may involve non haematopoietic cells, and they may result in single episode of illness, with a single or multiple morbid phenotypes, some of which may involve infection, in otherwise healthy adults. We need to increase awareness of the multitude of clinical presentations of human PIDs considerably and rapidly in the medical community. Human PIDs should be considered in a wide range of clinical situations.

The novel IFNGR1 mutation 774del4 produces a truncated form of interferon-γ receptor 1 and has a dominant-negative effect on interferon-γ signal transduction

Background: Patients with interferon-γ receptor 1 (IFNγR1) deficiency show selective susceptibility to intracellular pathogens such as mycobacteria. IFNγR1 deficiency is an inherited immunodeficiency disorder, which can be either recessive or...

A Novel Mutation 774del4 in IFNGR1, Which Produces Truncated Form of Interferon γ Receptor 1, Causes a Dominant-Negative Effect on Interferon γ Signal Transduction.

Patients with interferon γ receptor 1 (IFNγR1) deficiency are characterized by disseminated Bacilli Calmette-Guérin (BCG) infections and severe non-tuberculosis mycobacterium infections, and show remarkable genetic heterogeneity. It is known as one of inherited immunodeficiency disorders with recessive or dominant form. So far known dominant forms of IFNγR1 deficiency are associated with heterozygous mutation in the intracellular domain of IFNγR1, among of which 818del4 is known as a major mutation in IFNGR1, leading to frameshift and premature stop codon. We describe here a novel heterozygous IFNGR1 mutation in a patient with recurrent mycobacterium infections, resulting in impairment of receptor degradation. The proband, a 12-year old Japanese girl, developed multiple osteomyelitis due to M. avium infection. She had suffered from BCG lymphadenitis, which occurred 2 months after BCG vaccination, for 3 years. DNA sequence analysis of IFNGR1 demonstrated that the patient had a heterozygous mutation 774del4, producing a truncated protein lacking intracellular component of IFNγR1. IFNγR1 was overexpressed on the surface of CD14-positive cells in the peripheral blood of the patient, and STAT1 phosphorylation was partially defected in response to high dose IFN-γ stimulation. Impaired TNF-α production in response to IFN-γ stimulation was also observed. T cells from the patient presented decreased IFN-γ production in response to IL-12 stimulation.In order to define the characterization of this truncated form of IFNγR1, we cloned 774del4 and 818del4 mutations as well as the wild-type into mammalian expression vector. These constructs were transfected into HEK293 cells. Cycloheximide (CHX) treatment enabled detection of IFNγR1 expression by flow cytometry and Western blot analysis. In contrast to the wild-type IFNγR1 protein, which rapidly disappeared after CHX treatment, 774del4 mutant protein was stably retained on the cell surface as was observed in 818del4 mutant. These observations suggest that 774del4 mutant causes overexpression of dominant-negative form of IFNγR1 on the cell surface through impairment of receptor degradation.

HHV-8–associated Kaposi sarcoma in a child with IFNγR1 deficiency

Objectives Mediterranean classic Kaposi sarcoma (KS) of childhood is rare and unexplained. Our objective is to describe the case of a child with complete IFNγR1 deficiency and severe mycobacterial disease in whom Kaposi sarcoma (KS) developed. Results Disseminated mycobacterial infection began at the age of 5 months, and at 11 years of age the child had disseminated KS lesions. The histologic appearance of these lesions was typical, with endothelial and spindle cell proliferation. Human herpesvirus-8 (HHV-8)-associated antigens were detected in situ by immunohistochemistry. HHV-8 DNA of K1 molecular subtype A was amplified from tissue lesions, and HHV-8–specific antibodies were detected in the patient's serum. The child died at 12 years of age of disseminated mycobacterial disease and KS. Conclusions This is the first identification of a well-defined primary immunodeficiency in a child with KS. Inherited disorders of IFN-γ–mediated immunity and severe mycobacterial disease may predispose HHV-8–infected children to KS.

Successful HLA-identical bone marrow transplantation in a patient with interferon-γ receptor 2 deficiency and disseminated Mycobacterium avium complex infection

Interferon gamma receptor-2 (IFNγR2) deficiency is characterized by increased susceptibility to nontuberculous mycobacteria and intracellular pathogens. We report successful HLA-identical bone marrow transplantation (BMT) of a patient with this defect. A Qatari male born to consanguineous parents presented with a CMV positive urine culture, while blood and urine mycobacterial cultures were initially negative. Bacille-Calmette-Guerin (BCG) vaccine was not administered due to a history of IFN-γ R2 deficiency in his deceased older sister. The patient was found to have the same defect. Parents initially refused BMT. He received prophylactic azithromycin but developed disseminated Mycobacterium avium complex (MAC) infection requiring an aggressive regimen including amikacin, azithromycin, ethambutol, linezolid, rifampin and moxifloxacin. CMV infection was treated with ganciclovir, foscarnet, and CMV immune globulin. Splenectomy was performed at age 9 months, due to massive hypersplenism with subsequent growth of MAC. CMV DNA was positive until age 11 months, while mycobacterial blood cultures were positive until age 10 months. At age 13 months, he underwent bone marrow transplantation from his HLA-identical father. Pre-transplant conditioning included busulfan, cyclophosphamide, and antithymocyte globulin (ATG). Post-transplant graft vs. host disease prophylaxis included methotrexate and cyclosporine. RFLP analysis revealed 98% donor cells on day +32 post-transplant. Transplant course was complicated by Clostridium difficile infection, fevers, hypertension and thrombocytopenia, but he is stable 94 days post-transplantation. Conclusions Our case is the only living patient who has undergone successful BMT for a defect in the IFNγR2. We conclude that bone marrow transplantation for IFNγR2 deficiency is an effective means of correcting this immunodeficiency.

Persistent Mycobacterium avium infection following nonmyeloablative allogeneic peripheral blood stem cell transplantation for interferon-γ receptor-1 deficiency

AbstractInterferon-γ receptor-1 (IFNγR1) deficiency is a rare inherited immunodeficiency. We performed a nonmyeloablative allogeneic stem cell transplantation on a boy with complete IFNγR1 deficiency and refractory disseminated Myco-bacterium avium infection. Despite the patient’s profound immune defect, early donor stem cell engraftment was low. Full donor engraftment was accomplished only following multiple donor lymphocyte infusions. Detection of IFNγR1 expression on peripheral blood monocytes and neutrophils corresponded with establishment of stable, complete donor hematopoietic chimerism. However, expression of, and signaling through IFNγR1 disappeared shortly thereafter. Disseminated Mycobacterium avium infection persisted and the patient died. Coculture of Myco-bacterium avium with normal myeloid cells resulted in an IFNγ signaling defect similar to that observed in vivo. Active disseminated Mycobacterium avium infection may significantly compromise normal immune reconstitution following allogeneic stem cell transplantation. Patients with IFNγR1 deficiency should receive transplants before developing refractory mycobacterial infections. (Blood. 2003;102:2692-2694)

Impaired interferon gamma-mediated immunity and susceptibility to mycobacterial infection in childhood.

Mendelian susceptibility to poorly virulent mycobacteria such as bacillus Calmette-Guerin (BCG) and environmental nontuberculous mycobacteria is a clinically heterogeneous syndrome. The clinical features of affected children cover a continuous spectrum from disseminated lethal bacillus Calmette-Guerin infection to local recurrent nontuberculous mycobacterial infection. Different types of mutations in four genes (IFNGR1, IFNGR2, IL12B, IL12RB1) have revealed both allelic and nonallelic heterogeneity and result in eight different disorders whose common pathogenic pathway is impaired interferon gamma (IFNgamma) mediated immunity. The severity of the clinical phenotype depends on the genotype. Complete IL-12 p40 and IL-12 receptor beta1 deficiencies and partial IFNgamma receptor 1 (IFNgammaR1) and IFNgammaR2 deficiencies generally lead to curable infections at various ages, and antibiotics supplemented with IFNgamma if required are likely to be effective. Complete IFNgammaR1 and IFNgammaR2 deficiencies predispose to overwhelming infection in early childhood, which may respond to antibiotics but relapse when antibiotics are discontinued. Rapid discrimination between complete IFNgammaR1 and IFNgammaR2 deficiency and other defects, therefore, is an important diagnostic step for planning clinical management.

A Point Mutation in a Domain of Gamma Interferon Receptor 1 Provokes Severe Immunodeficiency

Gamma interferon (IFN-gamma) and the cellular responses induced by it are essential for controlling mycobacterial infections. Most patients bearing an IFN-gamma receptor ligand-binding chain (IFN-gammaR1) deficiency present gross mutations that truncate the protein and prevent its expression, giving rise to severe mycobacterial infections and, frequently, a fatal outcome. In this report a new mutation that affects the IFN-gammaR1 ligand-binding domain in a Spanish patient with mycobacterial disseminated infection and multifocal osteomyelitis is characterized. The mutation generates an amino acid change that does not abrogate protein expression on the cellular surface but that severely impairs responses after the binding of IFN-gamma (CD64 and HLA class II induction and tumor necrosis factor alpha and interleukin-12 production). A patient's younger brother, who was also probably homozygous for the mutation, died from meningitis due to Mycobacterium bovis. These findings suggest that a point mutation may be fatal when it affects functionally important domains of the receptor and that the severity is not directly related to a lack of IFN-gamma receptor expression. Future research on these nontruncating mutations will make it possible to develop new therapeutical alternatives in this group of patients.