Novel mutation and expanding phenotype in IRF2BP2 deficiency.

OBJECTIVES: Inborn errors of immunity manifest with susceptibility to infection but may also present with immune dysregulation only. According to the European Society for Immunodeficiencies Registry about 50% of inborn errors of immunity are classified as common variable immunodeficiencies (CVID). In only few CVID patients are monogenic causes identified. IFN regulatory factor-2 binding protein 2 (IRF2BP2) is one of 20 known genes associated with CVID phenotypes and has only been reported in two families so far. We report another IRF2BP2-deficient patient with a novel pathogenic variant and phenotype and characterize impaired B cell function and immune dysregulation. METHODS: We performed trio whole-exome sequencing, determined B cell subpopulations and intracellular calcium mobilization upon B cell receptor crosslinking in B cells. T cell subpopulations, T cell proliferation and a type I IFN signature were measured. Colonoscopy and gastroduodenoscopy including histopathology were performed. RESULTS: The 33-year-old male presented with recurrent respiratory infections since childhood, colitis and RA beginning at age 25 years. We identified a novel de novo nonsense IRF2BP2 variant c.1618C>T; p.(Q540*). IgG deficiency was detected as consequence of a severe B cell differentiation defect. This was confirmed by impaired plasmablast formation upon stimulation with CpG. No serum autoantibodies were detected. Intracellular cytokine production in CD4+ T cells and CTLA4 expression on FOXP3+ Tregs were impaired. Type I IFN signature was elevated. CONCLUSION: The identified loss-of-function variant in IRF2BP2 severely impairs B cell development and T cell homeostasis, and may be associated with colitis and RA. Our results provide further evidence for association of IRF2BP2 with CVID and contribute to the understanding of the underlying pathomechanisms.

Hyper-IgE and Carcinoma in CADINS Disease.

Background: Atopic dermatitis (AD) affects up to 25% of children and 10% of adults in Western countries. When severe or recurrent infections and exceedingly elevated serum IgE levels occur in AD patients, an inborn error of immunity (IEI) may be suspected. The International Union of Immunological Societies classification lists variants in different genes responsible for so-called Hyper-IgE syndromes. Diagnosing an underlying IEI may influence treatment strategies. Methods: Clinical and diagnostic workup of family members are presented including a detailed immunological description and histology of the carcinoma. Functional testing of the novel variant in CARD11 underlying 'CARD11-associated atopy with dominant interference of NF-kB signaling' (CADINS) was performed. Results: We report on an 18-year-old patient with a long-standing history of infections, accompanied by hypogammaglobulinemia, intermittent agranulocytosis, atopy, eosinophilia and colitis. The working diagnosis of common variable immunodeficiency was revised when a novel heterozygous CARD11 variant [c.223C>T; p.(Arg75Trp)] was identified. Functional studies confirmed this variant to have a dominant negative (DN) effect, as previously described in patients with CADINS. Five other family members were affected by severe atopy associated with the above variant, but not hypogammaglobulinemia. Malignancies occurred in two generations: an HPV-positive squamous cell carcinoma and a cutaneous T-cell lymphoma. So far, one patient is under treatment with dupilumab, which has shown marked benefit in controlling severe eczema. Conclusion: The phenotypic spectrum associated with heterozygous CARD11 DN mutations is broad. Partial T-cell deficiency, diminished IFN-γ cytokine and increased IL-4 production, were identified as disease-causing mechanisms. Malignant disease associated with germline CARD11 DN variants has only been reported sporadically. HPV vaccination in teenage years, and cytology screening analogous with routine cervical swabs may be recommended. Treatment with dupilumab, a monoclonal antibody blocking interleukin-4- and interleukin-13 signaling, may be of benefit in controlling severe and extended AD for some patients as reported for STAT3 loss-of-function.

Hematologically important mutations: The autosomal forms of chronic granulomatous disease (third update).

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. CGD patients suffer from severe, recurrent bacterial and fungal infections. The disease is caused by mutations in the genes encoding the components of the leukocyte NADPH oxidase. This enzyme produces superoxide, which is subsequently metabolized to hydrogen peroxide and other reactive oxygen species (ROS). These products are essential for intracellular killing of pathogens by phagocytic leukocytes (neutrophils, eosinophils, monocytes and macrophages). The leukocyte NADPH oxidase is composed of five subunits, four of which are encoded by autosomal genes. These are CYBA, encoding p22phox, NCF1, encoding p47phox, NCF2, encoding p67phox and NCF4, encoding p40phox. This article lists all mutations identified in these genes in CGD patients. In addition, cytochrome b558 chaperone-1 (CYBC1), recently recognized as an essential chaperone protein for the expression of the X-linked NADPH oxidase component gp91phox (also called Nox2), is encoded by the autosomal gene CYBC1. Mutations in this gene also lead to CGD. Finally, RAC2, a small GTPase of the Rho family, is needed for activation of the NADPH oxidase, and mutations in the RAC2 gene therefore also induce CGD-like symptoms. Mutations in these last two genes are also listed in this article.

Hematologically important mutations: X-linked chronic granulomatous disease (fourth update).

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. CGD patients suffer from severe bacterial and fungal infections. The disease is caused by a lack of superoxide production by the leukocyte enzyme NADPH oxidase. Superoxide and subsequently formed other reactive oxygen species (ROS) are instrumental in killing phagocytosed micro-organisms in neutrophils, eosinophils, monocytes and macrophages. The leukocyte NADPH oxidase is composed of five subunits, of which the enzymatic component is gp91phox, also called Nox2. This protein is encoded by the CYBB gene on the X chromosome. Mutations in this gene are found in about 70% of all CGD patients in Europe and in about 20% in countries with a high ratio of parental consanguinity. This article lists all mutations identified in CYBB and should therefore help in genetic counseling of X-CGD patients' families. Moreover, apparently benign polymorphisms in CYBB are also given, which should facilitate the recognition of disease-causing mutations. In addition, we also include some mutations in G6PD, the gene on the X chromosome that encodes glucose-6-phosphate dehydrogenase, because inactivity of this enzyme may lead to shortage of NADPH and thus to insufficient activity of NADPH oxidase. Severe G6PD deficiency can induce CGD-like symptoms.

Hematopoietic Stem Cell Transplantation Cures Therapy-refractory Aspergillosis in Chronic Granulomatous Disease.

BACKGROUND: Pulmonary invasive aspergillosis is a frequent and life-threatening complication for patients with chronic granulomatous disease (CGD). Despite combined treatment with several groups of antifungal agents, conservative treatment of invasive aspergillosis often remains refractory. Pulmonary invasive aspergillosis is often treated by surgical resection of consolidated lobes or segments, donor granulocyte transfusions and allogeneic hematopoietic stem cell transplantation (HSCT). These options are not mutually exclusive and often combined. METHODS AND RESULTS: We here describe the treatment of 3 patients with CGD who received HSCT upon active pulmonary invasive aspergillosis: Two of them received HSCT as salvage therapy for refractory aspergillosis, and 1 patient received elective HSCT in infancy but developed pulmonary aspergillosis during secondary graft failure. Based on our experience and available literature, we discuss indication as well as timing of HSCT, granulocyte transfusions and surgery in patients with CGD and pulmonary invasive aspergillosis. CONCLUSIONS: Upon diagnosis with invasive aspergillosis in CGD, we propose to start antifungal treatment and preparation for HSCT at the same time. Remission of pulmonary invasive aspergillosis before HSCT remains preferable but is not mandatory. When pulmonary aspergillosis in patients with CGD remains refractory for longer than 3 months on conservative treatment, HSCT without prior surgery or accompanying granulocyte transfusions is a feasible option.

Outcome of chronic granulomatous disease - Conventional treatment vs stem cell transplantation.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) can cure chronic granulomatous disease (CGD), but it remains debated whether all conventionally treated CGD patients benefit from HSCT. METHODS: We retrospectively analyzed 104 conventionally treated CGD patients, of whom 50 patients underwent HSCT. RESULTS: On conventional treatment, seven patients (13%) died after a median time of 16.2 years (interquartile range [IQR] 7.0-18.0). Survival without severe complications was 10 ± 3% (mean ± SD) at the age of 20 years; 85% of patients developed at least one infection, 76% one non-infectious inflammation. After HSCT, 44 patients (88%) were alive at a median follow-up of 2.3 years (IQR 0.8-4.9): Six patients (12%) died from infections. Survival after HSCT was significantly better for patients transplanted ≤8 years (96 ± 4%) or for patients without active complications at HSCT (100%). Eight patients suffered from graft failure (16%); six (12%) developed acute graft-vs-host disease requiring systemic treatment. Conventionally treated patients developed events that required medical attention at a median frequency of 1.7 (IQR 0.8-3.2) events per year vs 0 (IQR 0.0-0.5) in patients beyond the first year post-HSCT. While most conventionally treated CGD patients failed to thrive, catch-up growth after HSCT in surviving patients reached the individual percentiles at the age of diagnosis of CGD. CONCLUSION: Chronic granulomatous disease patients undergoing HSCT until 8 years of age show excellent survival, but young children need more intense conditioning to avoid graft rejection. Risks and benefits of HSCT for adolescents and adults must still be weighed carefully.

Matched Family Donor Lymphocyte Infusions as First Cellular Therapy for Patients with Severe Primary T Cell Deficiencies.

Patients with primary immunodeficiencies caused by severe defects in T cell immunity are at risk of acquiring life-threatening infections. Cellular therapies are necessary to establish normal T cell function and to allow for long-term survival. This is most commonly achieved by hematopoietic stem cell transplantation (HSCT), but the outcome of this procedure is impaired if active infections are present at the time of HSCT. Donor lymphocyte infusions (DLIs) are a well-established therapeutic strategy following HSCT to treat viral infections, improve donor cell engraftment, or achieve graft-versus-leukemia activity in malignant disease. Here we present a cohort of 6 patients with primary T cell deficiencies who received transfusions of unselected mature donor lymphocytes prior and not directly related to allogeneic HSCT. DLIs obtained from the peripheral blood of HLA-identical (10/10) family donors were transfused without prior conditioning to treat or prevent life-threatening infections. All patients are alive with a follow-up of 0.5 to 16.5 years after the initial T cell administration. Additional cellular therapies were administered in 5 of 6 patients at 0.8 to 15 months after the first DLI. Mild cutaneous graft-versus-host disease (GVHD, stage ≤2) was observed in 3 of 6 patients and resolved spontaneously. We provide evidence that unselected HLA-identical DLIs can effectively prevent or contribute to overcome infections with a limited risk for GVHD in T cell deficient patients. The T cell system established by this readily available source can provide T cell function for years and can serve as a bridge to additional cellular therapies or, in specific conditions, as definite treatment.

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

BACKGROUND: Unlike infections with mycobacteria, reports of unusual viral infections in interferon-gamma-receptor (IFNγR) deficient patients are scarce. Therefore, discussion about increased susceptibility to viral infections in these patients is ongoing. CASE PRESENTATION: We describe a 51-year-old male with dominant partial interferon-gamma-receptor-1 (IFNγR1)-deficiency and recurrent Herpes simplex 2 meningoencephalitis as well as other viral reactivations since childhood. CONCLUSIONS: This case further confirms an enhanced risk for viral disease in IFNγR-deficient patients and a role of interferon gamma for human antiviral defense.

Author Correction: Human FCHO1 deficiency reveals role for clathrin-mediated endocytosis in development and function of T cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Non-canonical Caspase-1 Signaling Drives RIP2-Dependent and TNF-α-Mediated Inflammation In Vivo.

Pro-inflammatory caspase-1 is a key player in innate immunity. Caspase-1 processes interleukin (IL)-1ß and IL-18 to their mature forms and triggers pyroptosis. These caspase-1 functions are linked to its enzymatic activity. However, loss-of-function missense mutations in CASP1 do not prevent autoinflammation in patients, despite decreased IL-1ß production. In vitro data suggest that enzymatically inactive caspase-1 drives inflammation via enhanced nuclear factor κB (NF-κB) activation, independent of IL-1ß processing. Here, we report two mouse models of enzymatically inactive caspase-1-C284A, demonstrating the relevance of this pathway in vivo. In contrast to Casp1-/- mice, caspase-1-C284A mice show pronounced hypothermia and increased levels of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and IL-6 when challenged with lipopolysaccharide (LPS). Caspase-1-C284A signaling is RIP2 dependent and mediated by TNF-α but independent of the NLRP3 inflammasome. LPS-stimulated whole blood from patients carrying loss-of-function missense mutations in CASP1 secretes higher amounts of TNF-α. Taken together, these results reveal non-canonical caspase-1 signaling in vivo.

Human FCHO1 deficiency reveals role for clathrin-mediated endocytosis in development and function of T cells.

Clathrin-mediated endocytosis (CME) is critical for internalisation of molecules across cell membranes. The FCH domain only 1 (FCHO1) protein is key molecule involved in the early stages of CME formation. The consequences of mutations in FCHO1 in humans were unknown. We identify ten unrelated patients with variable T and B cell lymphopenia, who are homozygous for six distinct mutations in FCHO1. We demonstrate that these mutations either lead to mislocalisation of the protein or prevent its interaction with binding partners. Live-cell imaging of cells expressing mutant variants of FCHO1 provide evidence of impaired formation of clathrin coated pits (CCP). Patient T cells are unresponsive to T cell receptor (TCR) triggering. Internalisation of the TCR receptor is severely perturbed in FCHO1-deficient Jurkat T cells but can be rescued by expression of wild-type FCHO1. Thus, we discovered a previously unrecognised critical role of FCHO1 and CME during T-cell development and function in humans.

Rapid and Sustained Long-Term Efficacy and Safety of Canakinumab in Patients With Cryopyrin-Associated Periodic Syndrome Ages Five Years and Younger.

OBJECTIVE: To assess long-term efficacy and safety of canakinumab and the response to vaccination in children ages ≤5 years with cryopyrin-associated periodic syndrome (CAPS). METHODS: CAPS patients (ages ≤5 years) received 2 mg/kg canakinumab subcutaneously every 8 weeks; patients with neonatal-onset multisystem inflammatory disease (NOMID) received a starting dose of 4 mg/kg in this open-label trial. Efficacy was evaluated using physician global assessment of disease activity and serum levels of C-reactive protein (CRP) and amyloid A (SAA). Adverse events (AEs) were recorded. Vaccination response was evaluated using postvaccination antibody titers at 4 and 8 weeks after immunization. RESULTS: Of the 17 patients enrolled, 12 (71%) had Muckle-Wells syndrome, 4 (24%) had NOMID, and 1 (6%) had familial cold autoinflammatory syndrome. All 17 patients had a complete response to canakinumab. Disease activity improved according to the physician global assessment, and for 65% of the patients autoinflammatory disease was characterized as "absent" at the end of the study. Median CRP levels decreased over time. No such change was evident in SAA levels. During the extension study, postvaccination antibody titers increased above protective levels in 16 (94%) of 17 assessable vaccinations. Ten of the patients (59%) had AEs suspected to be related to canakinumab; 8 (47%) experienced at least 1 serious AE (SAE). None of the AEs or SAEs required interruption of canakinumab therapy. CONCLUSION: Our findings indicate that canakinumab effectively maintains efficacy through 152 weeks and appears to have no effect on the ability to produce antibodies against standard childhood non-live vaccines. The safety profile of canakinumab was consistent with previous studies, supporting long-term use of canakinumab for CAPS in children ≤5 years of age.

Genetic Diagnostic Elucidation of a Patient With Multiorgan Granulomas, Facial Peculiarities, and Psychomotor Retardation.

We report the case of a 19-years-old patient who presented with a perplexing variety of symptoms which included remarkable facial features, intellectual disability, granulomatous upper lip swelling (previously diagnosed as Melkersson-Rosenthal syndrome), Crohn's-like disease, non-productive cough, and a granulomatous mass localized in the left lung. Chronic granulomatous disease (CGD) was diagnosed using dihydrorhodamine 123 assay that showed low levels of phagocytic NADPH-oxidase. DNA sequencing revealed a heterozygous mutation in the NCF-1 gene on chromosome 7. As remarkable facial features and psychomotor retardation are not associated with CGD, a more detailed genetic work-up using fluorescence in situ hybridization was performed. A microdeletion in 7q11.23 on one allele indicated Williams-Beuren syndrome (WBS). The NCF-1 gene and its two pseudogenes are part of a highly repetitive region within 7q11.23 and are prone to recombination events and deletions. Such deletions can involve both the WBS critical region and the NCF-1 wildtype gene, as was the case for our patient. The second allele of the NCF-1 gene was affected by the frequent c.75.76delGT mutation that stems from a recombination of the NCF-1 wildtype gene with one of its pseudogenes. In conclusion, patients with NCF-1-deficient CGD may also harbor microdeletions that result in WBS or other hereditary disorders; therefore, it is important to perform a thorough genetic analysis in order to initiate appropriate therapy for these patients.

Impaired IFNγ-Signaling and Mycobacterial Clearance in IFNγR1-Deficient Human iPSC-Derived Macrophages.

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of interferon gamma (IFNγ) immunity and is characterized by severe infections by weakly virulent mycobacteria. Although IFNγ is the macrophage-activating factor, macrophages from these patients have never been studied. We demonstrate the generation of heterozygous and compound heterozygous (iMSMD-cohet) induced pluripotent stem cells (iPSCs) from a single chimeric patient, who suffered from complete autosomal recessive IFNγR1 deficiency and received bone-marrow transplantation. Loss of IFNγR1 expression had no influence on the macrophage differentiation potential of patient-specific iPSCs. In contrast, lack of IFNγR1 in iMSMD-cohet macrophages abolished IFNγ-dependent phosphorylation of STAT1 and induction of IFNγ-downstream targets such as IRF-1, SOCS-3, and IDO. As a consequence, iMSMD-cohet macrophages show impaired upregulation of HLA-DR and reduced intracellular killing of Bacillus Calmette-Guérin. We provide a disease-modeling platform that might be suited to investigate novel treatment options for MSMD and to gain insights into IFNγ signaling in macrophages.

International multi-centre study of pregnancy outcomes with interleukin-1 inhibitors.

Objective: To provide outcome data concerning pregnancies exposed to the Interleukin-1 (IL-1) inhibitors prior to conception in both men and women, during pregnancy and breast feeding. Methods: Retrospective data were collected from members of the International Society for Systemic Autoinflammatory diseases and collated in a single centre. A uniform data collection sheet was used to obtain standardized data including maternal age and diagnosis, type, duration of and response to IL-1 blockade, pregnancy duration, delivery, mode of feeding and neonatal development. Results: There were 31 maternal-exposed pregnancies from seven countries and we report the first data on paternal exposure: six to anakinra and five to canakinumab, with no negative outcomes. We also report the first data on canakinumab-exposed pregnancies: eight pregnancies that resulted in the delivery of seven healthy infants of normal gestational age and birthweight. There were 23 anakinra-exposed pregnancies resulting in the birth of 21 healthy infants, and one baby with unilateral renal agenesis and ectopic neurohypophysis. There were two first trimester miscarriages affecting a mother with active disease. There were no serious neonatal infections. Fourteen infants were breast fed with no complications. There were no reports of developmental delay, with follow-up of up to 10 years (median 18 months). Conclusion: This series substantially increases the published experience of IL-1 blockade and reproduction including the first data on canakinumab and on paternal exposure to these agents. Data are generally reassuring, although the case of renal agenesis is the second reported in an anakinra-exposed pregnancy.

Variant PIK3R1 Hypermorphic Mutation and Clinical Phenotypes in a Family with Short Statures, Mild Immunodeficiency and Lymphoma.

Background Heterozygous point mutations in the GT splice donor consensus sequence of exon 11 of the PIK3R1 gene (coding for p85α, p55α, and p50α regulatory subunits of PI3K) lead to exon skipping and thereby to an aberrant protein that leaves PI3K hyperactivated. Several patients with this particular variant of PI3 kinase delta syndrome (APDS) suffering from sinopulmonary infections and lymphoproliferation have been described. Methods (Whole exome) sequencing, evaluation of cellular and clinical phenotypes. Results We here report a family with a new heterozygous mutation in this gene, a 9 bp deletion (c.1418_1425+1del) that, however, leads to the same skipping of exon 11. The clinical phenotypes of their members partly overlap features of patients of other reports. Conclusions We found a new mutation in PIK3R1 and show how broad the resulting clinical spectrum can be.

Disturbed B-lymphocyte selection in autoimmune lymphoproliferative syndrome.

Fas is a transmembrane receptor involved in the maintenance of tolerance and immune homeostasis. In murine models, it has been shown to be essential for deletion of autoreactive B cells in the germinal center. The role of Fas in human B-cell selection and in development of autoimmunity in patients carrying FAS mutations is unclear. We analyzed patients with either a somatic FAS mutation or a germline FAS mutation and somatic loss-of-heterozygosity, which allows comparing the fate of B cells with impaired vs normal Fas signaling within the same individual. Class-switched memory B cells showed: accumulation of FAS-mutated B cells; failure to enrich single V, D, J genes and single V-D, D-J gene combinations of the B-cell receptor variable region; increased frequency of variable regions with higher content of positively charged amino acids; and longer CDR3 and maintenance of polyreactive specificities. Importantly, Fas-deficient switched memory B cells showed increased rates of somatic hypermutation. Our data uncover a defect in B-cell selection in patients with FAS mutations, which has implications for the understanding of the pathogenesis of autoimmunity and lymphomagenesis of autoimmune lymphoproliferative syndrome.

Functional Restoration of gp91phox-Oxidase Activity by BAC Transgenesis and Gene Targeting in X-linked Chronic Granulomatous Disease iPSCs.

Chronic granulomatous disease (CGD) is an inherited immunodeficiency, caused by the inability of neutrophils to produce functional NADPH oxidase required for fighting microbial infections. The X-linked form of CGD (X-CGD), which is due to mutations in the CYBB (gp91phox) gene, a component of NADPH oxidase, accounts for about two-thirds of CGD cases. We derived induced pluripotent stem cells (iPSCs) from X-CGD patient keratinocytes using a Flp recombinase excisable lentiviral reprogramming vector. For restoring gp91phox function, we applied two strategies: transposon-mediated bacterial artificial chromosome (BAC) transgenesis and gene targeting using vectors with a fixed 5' homology arm (HA) of 8 kb and 3'HA varying in size from 30 to 80 kb. High efficiency of homologous recombination (up to 22%) was observed with increased size of the 3'HA. Both, BAC transgenesis and gene targeting resulted in functional restoration of the gp91phox measured by an oxidase activity assay in X-CGD iPSCs differentiated into the myeloid lineage. In conclusion, we delivered an important milestone towards the use of genetically corrected autologous cells for the treatment of X-CGD and monogenic diseases in general.

Neutrophil oxidative burst activates ATM to regulate cytokine production and apoptosis.

Neutrophils play an essential role in the initial stages of inflammation by balancing pro- and antiinflammatory signals. Among these signals are the production of proinflammatory cytokines and the timely initiation of antiinflammatory cell death via constitutive apoptosis. Here we identify ataxia-telangiectasia mutated (ATM) kinase as a modulator of these neutrophil functions. Ataxia-telangiectasia (AT) is a pleiotropic multisystem disorder caused by mutations in the gene-encoding ATM, a master regulator of the DNA damage response. In addition to progressive neurodegeneration and high rates of cancer, AT patients have numerous symptoms that can be linked to chronic inflammation. We report that neutrophils isolated from patients with AT overproduce proinflammatory cytokines and have a prolonged lifespan compared with healthy controls. This effect is partly mediated by increases in activation of p38 MAP kinase. Furthermore, we show that the oxidative burst, catalyzed by nicotinamide adenine dinucleotide phosphate oxidase, can activate ATM in neutrophils. Finally, activation of ATM and DNA damage signaling suppress cytokine production and can abrogate the overproduction of IL-8 in ROS-deficient cells. This reveals a novel mechanism for the regulation of cytokine production and apoptosis, establishing DNA damage as a downstream mediator of immune regulation by reactive oxygen species. We propose that deficiencies in the DNA damage response, like deficiencies in the oxidative burst seen in chronic granulomatous disease, could lead to pathologic inflammation.