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Background: In 2016, nationwide cystic fibrosis newborn screening (CFNS) was newly implemented in Germany, using an immunoreactive trypsin/pancreatitis-associated protein/DNA screening algorithm that differs from most other nationwide screening programmes., Methods: We analysed real-life feasibility of the confirmation process with respect to our pre-specified procedural objectives. These included overall accuracy through false-negative and false-positive results, effectiveness of the Bavarian tracking system, and accuracy of Macroduct and Nanoduct sweat conductivity compared with quantitative chloride determination. All consecutive CFNS-positive newborns assigned to our CF centre and born between 1 September 2016 and 31 August 2021 (n=162) were included., Results: The German CFNS was feasible at our CF centre as all procedural objectives were met. The positive predictive value (PPV) of positive CFNS was low (0.23) and two initially negatively screened children were later diagnosed with CF. The tracking system was highly efficient with a 100% tracking rate. The Macroduct and Nanoduct systems had comparable success rates (93.2% versus 95.9%). Importantly, conductivity via Macroduct was more accurate than via Nanoduct (zero and four false-positive newborns, respectively)., Conclusions: CF confirmation diagnostics of neonates in a certified regional CF centre was well managed in daily routine. The PPV of the German CFNS needs to be improved, e.g. by extending the DNA analysis within the screening algorithm and by increasing the number of variants tested. The Bavarian tracking system can serve as a successful model for other tracking systems. We preferred the Macroduct system because of its more accurate sweat conductivity readings., Competing Interests: Conflict of interest: All authors declare that they have no conflicts of interest., (Copyright ©The authors 2024.)

Background: Progress in rare and interstitial lung disease in childhood can most usefully be achieved through systematic, registry-based collection., Question and Methods: What are the practicalities and benefits of participating in the pediatric lung registry/chILD-EU project? We report our clinical experiences., Results: Pediatricians and pediatric pulmonologists identify children with rare lung diseases. These are reported to the Kid's Lung Register after parental consent. Clinical data, imaging, and blood are sent to the registry. Genetic analysis can be arranged if desired. With completeness of the data, a peer-review process by pediatric radiology, possibly lung pathology, clinical and possibly genetic experts takes place in an interdisciplinary conference. A working diagnosis is established and communicated to the responsible physician via the registry and, if necessary, further discussed in case-related discussions. Assistance in entering the data is provided by the registry. Follow-ups are performed annually, and all registered physicians are invited to regular, web-based case discussions. Significant questions are answered in scientific projects and jointly published (>110 publications to date)., Conclusions: Due to voluntary additional work of all participants beyond clinical routine, more than 1000 children with rare lung diseases have been included in the registry with biobank to date. A deeper understanding of the clinical courses of large cohorts of rare diseases and the initial description of new entities contributes to better care for these children., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

STAT2 is a transcription factor activated by type I and III IFNs. We report 23 patients with loss-of-function variants causing autosomal recessive (AR) complete STAT2 deficiency. Both cells transfected with mutant STAT2 alleles and the patients' cells displayed impaired expression of IFN-stimulated genes and impaired control of in vitro viral infections. Clinical manifestations from early childhood onward included severe adverse reaction to live attenuated viral vaccines (LAV) and severe viral infections, particularly critical influenza pneumonia, critical COVID-19 pneumonia, and herpes simplex virus type 1 (HSV-1) encephalitis. The patients displayed various types of hyperinflammation, often triggered by viral infection or after LAV administration, which probably attested to unresolved viral infection in the absence of STAT2-dependent types I and III IFN immunity. Transcriptomic analysis revealed that circulating monocytes, neutrophils, and CD8+ memory T cells contributed to this inflammation. Several patients died from viral infection or heart failure during a febrile illness with no identified etiology. Notably, the highest mortality occurred during early childhood. These findings show that AR complete STAT2 deficiency underlay severe viral diseases and substantially impacts survival.

Background: The majority of patients with childhood interstitial lung disease (chILD) caused by pathogenic variants in ATP binding cassette subfamily A member 3 (ABCA3) develop severe respiratory insufficiency within their first year of life and succumb to disease if not lung transplanted. This register-based cohort study reviews patients with ABCA3 lung disease who survived beyond the age of 1 year., Method: Over a 21-year period, patients diagnosed as chILD due to ABCA3 deficiency were identified from the Kids Lung Register database. 44 patients survived beyond the first year of life and their long-term clinical course, oxygen supplementation and pulmonary function were reviewed. Chest CT and histopathology were scored blindly., Results: At the end of the observation period, median age was 6.3 years (IQR: 2.8-11.7) and 36/44 (82%) were still alive without transplantation. Patients who had never received supplemental oxygen therapy survived longer than those persistently required oxygen supplementation (9.7 (95% CI 6.7 to 27.7) vs 3.0 years (95% CI 1.5 to 5.0), p = 0.0126). Interstitial lung disease was clearly progressive over time based on lung function (forced vital capacity % predicted absolute loss -1.1% /year) and on chest CT (increasing cystic lesions in those with repetitive imaging). Lung histology pattern were variable (chronic pneumonitis of infancy, non-specific interstitial pneumonia, and desquamative interstitial pneumonia). In 37/44 subjects, the ABCA3 sequence variants were missense variants, small insertions or deletions with in-silico tools predicting some residual ABCA3 transporter function., Conclusion: The natural history of ABCA3-related interstitial lung disease progresses during childhood and adolescence. Disease-modifying treatments are desirable to delay such disease course., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Diffuse alveolar hemorrhage (DAH) in children is a rare condition resulting from different underlying diseases. This study aimed at describing characteristics and diagnostic measures in children with ILD (children's interstitial lung disease, chILD) and DAH to improve the diagnostic approach by increasing clinician's awareness of diagnostic shortcomings., Patients and Methods: A retrospective data analysis of patients with ILD and DAH treated in our own or collaborating centers between 01/07/1997 and 31/12/2020 was performed. Data on clinical courses and diagnostic measures were systematically retrieved as case-vignettes and investigated. To assess suitability of diagnostic software-algorithms, the Human Phenotype Ontology (HPO) was revised and expanded to optimize conditions of its associated tool the "Phenomizer.", Results: For 97 (74%) of 131 patients, etiology of pulmonary hemorrhage was clarified. For 34 patients (26%), no underlying condition was found (termed as idiopathic pulmonary hemorrhage, IPH). Based on laboratory findings or clinical phenotype/comorbidities, 20 of these patients were assigned to descriptive clusters: IPH associated with autoimmune features (9), eosinophilia (5), renal disease (3) or multiorgan involvement (3). For 14 patients, no further differentiation was possible., Conclusion: Complete and sometimes repeated diagnostics are essential for establishing the correct diagnosis in children with DAH. We suggest assignment of patients with IPH to descriptive clusters, which may also guide further research. Digital tools such as the Phenomizer/HPO are promising, but need to be extended to increase diagnostic accuracy., (© 2023 The Authors. Pediatric Pulmonology published by Wiley Periodicals LLC.)

Patients with inherited CARMIL2 or CD28 deficiency have defective T cell CD28 signaling, but their immunological and clinical phenotypes remain largely unknown. We show that only one of three CARMIL2 isoforms is produced and functional across leukocyte subsets. Tested mutant CARMIL2 alleles from 89 patients and 52 families impair canonical NF-κB but not AP-1 and NFAT activation in T cells stimulated via CD28. Like CD28-deficient patients, CARMIL2-deficient patients display recalcitrant warts and low blood counts of CD4+ and CD8+ memory T cells and CD4+ TREGs. Unlike CD28-deficient patients, they have low counts of NK cells and memory B cells, and their antibody responses are weak. CARMIL2 deficiency is fully penetrant by the age of 10 yr and is characterized by numerous infections, EBV+ smooth muscle tumors, and mucocutaneous inflammation, including inflammatory bowel disease. Patients with somatic reversions of a mutant allele in CD4+ T cells have milder phenotypes. Our study suggests that CARMIL2 governs immunological pathways beyond CD28., (© 2022 Lévy et al.)

Macrophages are key target cells of Zika virus (ZIKV) infection, implicated as a viral reservoir seeding sanctuary sites such as the central nervous system and testes. This rests on the apparent ability of macrophages to sustain ZIKV replication without experiencing cytopathic effects. ZIKV infection of macrophages triggers an innate immune response involving type I interferons (IFN-I), key antiviral cytokines that play a complex role in ZIKV pathogenesis in animal models. To investigate the functional role of the IFN-I response we generated human induced pluripotent stem cell (iPSC)-derived macrophages from a patient with complete deficiency of IFNAR2 , the high affinity IFN-I receptor subunit. Accompanying the profound defect of IFN-I signalling in IFNAR2 deficient iPS-macrophages we observed significantly enhanced ZIKV replication and cell death, revealing the inherent cytopathicity of ZIKV towards macrophages. These observations were recapitulated by genetic and pharmacological ablation of IFN-I signalling in control iPS-macrophages and extended to a model of iPS-microglia. Thus, the capacity of macrophages to support noncytolytic ZIKV replication depends on an equilibrium set by IFN-I, suggesting that innate antiviral responses might counterintuitively promote ZIKV persistence via the maintenance of tissue viral reservoirs relevant to pathogenesis., Competing Interests: SH declares honoraria from CSL Behring and Takeda for teaching and consultancy. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hanrath, Hatton, Gothe, Browne, Vowles, Leary, Cockell, Cowley, James, Hambleton and Duncan.)

Background: Inflammatory phenomena such as hyperinflammation or hemophagocytic lymphohistiocytosis are a frequent yet paradoxical accompaniment to virus susceptibility in patients with impairment of type I interferon (IFN-I) signaling caused by deficiency of signal transducer and activator of transcription 2 (STAT2) or IFN regulatory factor 9 (IRF9)., Objective: We hypothesized that altered and/or prolonged IFN-I signaling contributes to inflammatory complications in these patients., Methods: We explored the signaling kinetics and residual transcriptional responses of IFN-stimulated primary cells from individuals with complete loss of one of STAT1, STAT2, or IRF9 as well as gene-edited induced pluripotent stem cell-derived macrophages., Results: Deficiency of any IFN-stimulated gene factor 3 component suppressed but did not abrogate IFN-I receptor signaling, which was abnormally prolonged, in keeping with insufficient induction of negative regulators such as ubiquitin-specific peptidase 18 (USP18). In cells lacking either STAT2 or IRF9, this late transcriptional response to IFN-α2b mimicked the effect of IFN-γ., Conclusion: Our data suggest a model wherein the failure of negative feedback of IFN-I signaling in STAT2 and IRF9 deficiency leads to immune dysregulation. Aberrant IFN-α receptor signaling in STAT2- and IRF9-deficient cells switches the transcriptional output to a prolonged, IFN-γ-like response and likely contributes to clinically overt inflammation in these individuals., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Lymphocyte differentiation is regulated by coordinated actions of cytokines and signaling pathways. IL-21 activates STAT1, STAT3, and STAT5 and is fundamental for the differentiation of human B cells into memory cells and antibody-secreting cells. While STAT1 is largely nonessential and STAT3 is critical for this process, the role of STAT5 is unknown., Objectives: This study sought to delineate unique roles of STAT5 in activation and differentiation of human naive and memory B cells., Methods: STAT activation was assessed by phospho-flow cytometry cell sorting. Differential gene expression was determined by RNA-sequencing and quantitative PCR. The requirement for STAT5B in B-cell and CD4 + T-cell differentiation was assessed using CRISPR-mediated STAT5B deletion from B-cell lines and investigating primary lymphocytes from individuals with germline STAT5B mutations., Results: IL-21 activated STAT5 and strongly induced SOCS3 in human naive, but not memory, B cells. Deletion of STAT5B in B-cell lines diminished IL-21-mediated SOCS3 induction. PBMCs from STAT5B-null individuals contained expanded populations of immunoglobulin class-switched B cells, CD21 lo Tbet + B cells, and follicular T helper cells. IL-21 induced greater differentiation of STAT5B-deficient B cells into plasmablasts in vitro than B cells from healthy donors, correlating with higher expression levels of transcription factors promoting plasma cell formation., Conclusions: These findings reveal novel roles for STAT5B in regulating IL-21-induced human B-cell differentiation. This is achieved by inducing SOCS3 to attenuate IL-21 signaling, and BCL6 to repress class switching and plasma cell generation. Thus, STAT5B is critical for restraining IL-21-mediated B-cell differentiation. These findings provide insights into mechanisms underpinning B-cell responses during primary and subsequent antigen encounter and explain autoimmunity and dysfunctional humoral immunity in STAT5B deficiency., (Copyright © 2022 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

In childhood, a multitude of causes lead to pulmonary alveolar proteinosis (PAP), an excessive surfactant accumulation in the alveolar space, limiting gas exchange. Autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) causing autoimmune PAP, the principal aetiology in adults, are rare. In this first case series on autoimmune PAP, we detail the presentation and management issues of four children. Whereas three children presented insidiously with progressive dyspnoea, one was acutely sick with suspected pneumonia. During management, one patient was hospitalised with coronavirus disease 2019, noninvasively ventilated, and recovered. All treatment modalities known from adults including whole-lung lavage, augmentation of GM-CSF by inhaled GM-CSF, removal of neutralising antibody by plasmapheresis and interruption of antibody production using rituximab were considered; however, not all options were available at all sites. Inhaled GM-CSF appeared to be a noninvasive and comfortable therapeutic approach. The management with best benefit-to-harm ratio in autoimmune PAP is unknown and specialised physicians must select the least invasive and most effective treatment. To collect this cohort in a rare condition became feasible as patients were submitted to an appropriate registry. To accelerate the authorisation of novel treatments for autoimmune PAP, competent authorities should grant an inclusion of adolescents into trials in adults., Competing Interests: Conflict of interest: M. Griese reports grants or contracts received from Böhringer Ingelheim paid to their institution; participation on a Data Safety Monitoring Board or Advisory Board for Böhringer Ingelheim, personal fees received. Unpaid Head chILD-EU; all disclosures made outside the submitted work. Conflict of interest: P. Panagiotou has nothing to disclose. Conflict of interest: E.D. Manali reports receiving grants or contracts, paid to their institution, from Hoffmann La Roche, Boehringer Ingelheim and Savara; personal payments for lectures, presentations, speakers' bureaus, manuscript writing or educational events received from Hoffmann La Roche and Boehringer Ingelheim; support for attending meetings and/or travel paid to the institution received from Hoffmann La Roche and Boehringer Ingelheim; all disclosures made outside the submitted work. Conflict of interest: M. Stahl has nothing to disclose. Conflict of interest: N. Schwerk has nothing to disclose. Conflict of interest: V. Costa has nothing to disclose. Conflict of interest: K. Douros has nothing to disclose. Conflict of interest: M. Kallieri has nothing to disclose. Conflict of interest: R.M. Urbantat has nothing to disclose. Conflict of interest: H. von Bernuth reports receiving payment or honoraria for lectures, presentations, speakers’ bureaus, manuscript writing or educational events from CSL Behring and Octapharma; participation on an advisory board for Takeda; and is an associate member of the Standing committee on vaccinations. All disclosures made outside the submitted work. Conflict of interest: L. Kolilekas has nothing to disclose. Conflict of interest: L. Morais has nothing to disclose. Conflict of interest: A. Ramos has nothing to disclose. Conflict of interest: K. Landwehr has nothing to disclose. Conflict of interest: K. Knoflach has nothing to disclose. Conflict of interest: F. Gothe has nothing to disclose. Conflict of interest: K. Reiter has nothing to disclose. Conflict of interest: V. Papaevangelou has nothing to disclose. Conflict of interest: A.G. Kaditis has nothing to disclose. Conflict of interest: C. Kanaka-Gantenbein has nothing to disclose. Conflict of interest: S.A. Papiris reports receiving grants or contracts paid to their institution from Hoffmann La Roche, Boehringer Ingelheim and Savara; personal payments received from Hoffmann La Roche and Boehringer Ingelheim for attending meetings and/or travel; all disclosures made outside the submitted work., (Copyright ©The authors 2022.)

The nasal epithelium is a plausible entry point for SARS-CoV-2, a site of pathogenesis and transmission, and may initiate the host response to SARS-CoV-2. Antiviral interferon (IFN) responses are critical to outcome of SARS-CoV-2. Yet little is known about the interaction between SARS-CoV-2 and innate immunity in this tissue. Here we apply single-cell RNA sequencing and proteomics to a primary cell model of human nasal epithelium differentiated at air-liquid interface. SARS-CoV-2 demonstrates widespread tropism for nasal epithelial cell types. The host response is dominated by type I and III IFNs and interferon-stimulated gene products. This response is notably delayed in onset relative to viral gene expression and compared to other respiratory viruses. Nevertheless, once established, the paracrine IFN response begins to impact on SARS-CoV-2 replication. When provided prior to infection, recombinant IFNβ or IFNλ1 induces an efficient antiviral state that potently restricts SARS-CoV-2 viral replication, preserving epithelial barrier integrity. These data imply that the IFN-I/III response to SARS-CoV-2 initiates in the nasal airway and suggest nasal delivery of recombinant IFNs to be a potential chemoprophylactic strategy., (© 2021. The Author(s).)

Gain-of-function variants in STAT3 are known to cause severe, multifaceted autoimmunity. Here we report three individuals with de-novo STAT3 GOF alleles and early-onset, severe interstitial lung disease manifesting during the first 3 years of life. Imaging and histology revealed different forms of interstitial pneumonia alongside fibrotic and cystic tissue destruction. Definitive diagnosis was established by postmortem whole exome sequencing and functional validation of two new STAT3 variants. Such lung-predominant forms of STAT3 GOF disease expand the phenotypic spectrum of diseases associated with activating STAT3 variants and add to our understanding of this life-threatening inborn error of immunity., (© 2021 The Authors. Pediatric Pulmonology published by Wiley Periodicals LLC.)

Accumulation of human CD21 low B cells in peripheral blood is a hallmark of chronic activation of the adaptive immune system in certain infections and autoimmune disorders. The molecular pathways underpinning the development, function, and fate of these CD21 low B cells remain incompletely characterized. Here, combined transcriptomic and chromatin accessibility analyses supported a prominent role for the transcription factor T-bet in the transcriptional regulation of these T-bet high CD21 low B cells. Investigating essential signals for generating these cells in vitro established that B cell receptor (BCR)/interferon-γ receptor (IFNγR) costimulation induced the highest levels of T-bet expression and enabled their differentiation during cell cultures with Toll-like receptor (TLR) ligand or CD40L/interleukin-21 (IL-21) stimulation. Low proportions of CD21 low B cells in peripheral blood from patients with defined inborn errors of immunity (IEI), because of mutations affecting canonical NF-κB, CD40, and IL-21 receptor or IL-12/IFNγ/IFNγ receptor/signal transducer and activator of transcription 1 (STAT1) signaling, substantiated the essential roles of BCR- and certain T cell–derived signals in the in vivo expansion of T-bet high CD21 low B cells. Disturbed TLR signaling due to MyD88 or IRAK4 deficiency was not associated with reduced CD21 low B cell proportions. The expansion of human T-bet high CD21 low B cells correlated with an expansion of circulating T follicular helper 1 (cTfh1) and T peripheral helper (Tph) cells, identifying potential sources of CD40L, IL-21, and IFNγ signals. Thus, we identified important pathways to target autoreactive T-bet high CD21 low B cells in human autoimmune conditions, where these cells are linked to pathogenesis and disease progression.

Live attenuated viral vaccines (LAV) have saved millions of lives globally through their capacity to elicit strong, cross-reactive and enduring adaptive immune responses. However, LAV can also act as a Trojan horse to reveal inborn errors of immunity, thereby highlighting important protective elements of the healthy antiviral immune response. In the following article, we draw out these lessons by reviewing the spectrum of LAV-associated disease reported in a variety of inborn errors of immunity. We note the contrast between adaptive disorders, which predispose to both LAV and their wild type counterparts, and defects of innate immunity in which parenterally delivered LAV behave in a particularly threatening manner. Recognition of the underlying pathomechanisms can inform our approach to disease management and vaccination in a wider group of individuals, including those receiving immunomodulators that impact the relevant pathways., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts (CD16 + C1QA/B/C + ) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34 + hematopoietic stem/progenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8 + T cells and an increased ratio of CD8 + effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy.

Background: Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus fumigatus contributing to cystic fibrosis (CF) lung disease., Objective: To evaluate the combination of oral prednisone for 18 days together with itraconazole therapy for at least 12 months in CF-related ABPA with regard to long-term pulmonary function and side effects., Methods: Sixty-five patients with CF treated for ABPA and 127 patients with CF without ABPA serving as matched controls were retrospectively analyzed for a median period of 4.8 years. Serial lung functions were analyzed alongside clinical, microbiological, and laboratory data including itraconazole therapeutic drug monitoring., Results: The used ABPA treatment regimen restored FEV 1 values to pre-ABPA levels within 3 months (P < .0001). Long-term FEV 1 courses of patients showed no difference when compared with those of ABPA-free controls. Glucocorticoid treatment was not associated with increased CF-related diabetes incidence, growth restriction, or Pseudomonas aeruginosa acquisition. Patients who experienced ABPA relapses displayed lower itraconazole trough levels during the first 3 months of treatment (P < .05). A decreased risk of ABPA recurrence was further associated with P aeruginosa colonization., Conclusions: The proposed treatment scheme for CF-related ABPA is effective in preserving lung function capacity over years in affected individuals without the known glucocorticoid-associated side effects. Itraconazole therapeutic drug monitoring seems useful to prevent disease flares, for which P aeruginosa-negative patients with CF might be particularly susceptible., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Excessive type I interferon (IFNα/β) activity is implicated in a spectrum of human disease, yet its direct role remains to be conclusively proven. We investigated two siblings with severe early-onset autoinflammatory disease and an elevated IFN signature. Whole-exome sequencing revealed a shared homozygous missense Arg148Trp variant in STAT2 , a transcription factor that functions exclusively downstream of innate IFNs. Cells bearing STAT2 R148W in homozygosity (but not heterozygosity) were hypersensitive to IFNα/β, which manifest as prolonged Janus kinase-signal transducers and activators of transcription (STAT) signaling and transcriptional activation. We show that this gain of IFN activity results from the failure of mutant STAT2 R148W to interact with ubiquitin-specific protease 18, a key STAT2-dependent negative regulator of IFNα/β signaling. These observations reveal an essential in vivo function of STAT2 in the regulation of human IFNα/β signaling, providing concrete evidence of the serious pathological consequences of unrestrained IFNα/β activity and supporting efforts to target this pathway therapeutically in IFN-associated disease., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Mutations in the coiled-coil and DNA-binding domains of STAT1 lead to delayed STAT1 dephosphorylation and subsequently gain-of-function. The associated clinical phenotype is broad and can include chronic mucocutaneous candidiasis (CMC) and/or combined immunodeficiency (CID). We report a case of CMC/CID in a 10-year-old boy due to a novel mutation in the small ubiquitin molecule (SUMO) consensus site at the C-terminal region of STAT1 leading to gain-of-function by impaired sumoylation. Immunodysregulatory features of disease improved after Janus kinase inhibitor (jakinib) treatment. Functional testing after treatment confirmed reversal of the STAT1 hyper-phosphorylation and downstream transcriptional activity. IL-17 and IL-22 production was, however, not restored with jakinib therapy (ruxolitinib), and the patient remained susceptible to opportunistic infection. In conclusion, a mutation in the SUMO consensus site of STAT1 can lead to gain-of-function that is reversible with jakinib treatment. However, full immunocompetence was not restored, suggesting that this treatment strategy might serve well as a bridge to definitive therapy such as hematopoietic stem cell transplant rather than a long-term treatment option.

Background: Children with very early onset inflammatory bowel diseases (VEO-IBD) often have a refractory and severe disease course. A significant number of described VEO-IBD-causing monogenic disorders can be attributed to defects in immune-related genes. The diagnosis of the underlying primary immunodeficiency (PID) often has critical implications for the treatment of patients with IBD-like phenotypes., Methods: To identify the molecular etiology in 5 patients from 3 unrelated kindred with IBD-like symptoms, we conducted whole exome sequencing. Immune workup confirmed an underlying PID., Results: Whole exome sequencing revealed 3 novel CARMIL2 loss-of-function mutations in our patients. Immunophenotyping of peripheral blood mononuclear cells showed reduction of regulatory and effector memory T cells and impaired B cell class switching. The T cell proliferation and activation assays confirmed defective responses to CD28 costimulation, consistent with CARMIL2 deficiency., Conclusion: Our study highlights that human CARMIL2 deficiency can manifest with IBD-like symptoms. This example illustrates that early diagnosis of underlying PID is crucial for the treatment and prognosis of children with VEO-IBD., (© 2019 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Interleukin-2, which conveys essential signals for immunity, operates through a heterotrimeric receptor. Here we identify human interleukin-2 receptor (IL-2R) β chain ( IL2RB ) gene defects as a cause of life-threatening immune dysregulation. We report three homozygous mutations in the IL2RB gene of eight individuals from four consanguineous families that cause disease by distinct mechanisms. Nearly all patients presented with autoantibodies, hypergammaglobulinemia, bowel inflammation, dermatological abnormalities, lymphadenopathy, and cytomegalovirus disease. Patient T lymphocytes lacked surface expression of IL-2Rβ and were unable to respond to IL-2 stimulation. By contrast, natural killer cells retained partial IL-2Rβ expression and function. IL-2Rβ loss of function was recapitulated in a recombinant system in which IL2RB mutations caused reduced surface expression and IL-2 binding. Stem cell transplant ameliorated clinical symptoms in one patient; forced expression of wild-type IL-2Rβ also increased the IL-2 responsiveness of patient T lymphocytes in vitro. Insights from these patients can inform the development of IL-2-based therapeutics for immunological diseases and cancer., (This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.)

Background: Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity disorder contributing to lung disease in cystic fibrosis (CF) and challenging to diagnose., Objective: This study analyzed the predictive value of increasing total IgE (t-IgE) levels in a CF cohort alongside with clinical and serologic data., Methods: A total of 387 children and young adults were followed from 2000 to 2006 and retrospectively classified into 6 groups. Patients with t-IgE levels < 95th percentile and without specific Aspergillus fumigatus (Af)-IgE were classified as "Naïve," those with Af-specific IgE (Af-sIgE) as "Sensitized." Patients with elevated t-IgE at entrance and Af-sIgE were labeled "Former ABPA," and those without, as "High t-IgE." Patients whose t-IgE values started normal and exceeded the 95th percentile during the study were labeled either "ABPA at risk" if Af-sIgE-positive or "Rising t-IgE" if not. Courses of t-IgE over time were divided into episodes with increasing IgE (ΔIgE) and related to pulmonary outcome., Results: A total of 125 patients were classified Naïve (32%), 64 Sensitized (17%), 49 ABPA at risk (13%), 32 Rising t-IgE (8%), 102 Former ABPA (26%), and 15 High t-IgE (4%). A total of 874 ΔIgE episodes were accompanied by forced expiratory volume in 1 second (FEV 1 ) declines (r = -0.21, P < .0001). Steroid treatment of severest ΔIgE episodes resulted in improved long-term pulmonary outcomes (P < .01). This FEV 1 preservation effect was only detectable if t-IgE levels at least doubled within 3 months and exceeded the 95th age-specific percentile (P < .05)., Conclusions: ΔIgE obtained from the course of t-IgE levels may be helpful in diagnosing treatment requiring ABPA and predicts the effect of systemic steroid treatment on pulmonary outcome., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Chronic mucocutaneous candidiasis (CMC) is defined as recurrent or persistent infection of the skin, nails, and/or mucosae with commensal Candida species. The first genetic etiology of isolated CMC-autosomal recessive (AR) IL-17 receptor A (IL-17RA) deficiency-was reported in 2011, in a single patient. We report here 21 patients with complete AR IL-17RA deficiency, including this first patient. Each patient is homozygous for 1 of 12 different IL-17RA alleles, 8 of which create a premature stop codon upstream from the transmembrane domain and have been predicted and/or shown to prevent expression of the receptor on the surface of circulating leukocytes and dermal fibroblasts. Three other mutant alleles create a premature stop codon downstream from the transmembrane domain, one of which encodes a surface-expressed receptor. Finally, the only known missense allele (p.D387N) also encodes a surface-expressed receptor. All of the alleles tested abolish cellular responses to IL-17A and -17F homodimers and heterodimers in fibroblasts and to IL-17E/IL-25 in leukocytes. The patients are currently aged from 2 to 35 y and originate from 12 unrelated kindreds. All had their first CMC episode by 6 mo of age. Fourteen patients presented various forms of staphylococcal skin disease. Eight were also prone to various bacterial infections of the respiratory tract. Human IL-17RA is, thus, essential for mucocutaneous immunity to Candida and Staphylococcus, but otherwise largely redundant. A diagnosis of AR IL-17RA deficiency should be considered in children or adults with CMC, cutaneous staphylococcal disease, or both, even if IL-17RA is detected on the cell surface., Competing Interests: The authors declare no conflict of interest.

Background: Aim of this study was to verify a systematic and practical categorization system that allows dynamic classification of pediatric DPLD irrespective of completeness of patient data., Methods: The study was based on 2322 children submitted to the kids-lung-register between 1997 and 2012. Of these children 791 were assigned to 12 DPLD categories, more than 2/3 belonged to categories manifesting primarily in infancy. The work-flow of the pediatric DPLD categorization system included (i) the generation of a final working diagnosis, decision on the presence or absence of (ii) DPLD and (iii) a systemic or lung only condition, and (iv) the allocation to a category and subcategory. The validity and inter-observer dependency of this workflow was re-tested using a systematic sample of 100 cases., Results: Two blinded raters allocated more than 80% of the re-categorized cases identically. Non-identical allocation was due to lack of appreciation of all available details, insufficient knowledge of the classification rules by the raters, incomplete patient data, and shortcomings of the classification system itself., Conclusions: This study provides a suitable workflow and hand-on rules for the categorization of pediatric DPLD. Potential pitfalls were identified and a foundation was laid for the development of consensus-based, international categorization guidelines.

Background and Aims: Measurement of 7 alpha-hydroxy-4-cholesten-3-one (C4) in serum is a semiquantitative test for bile acid malabsorption (BAM). We have previously established pediatric normal values for C4 with an upper limit of normal of 66.5 ng/mL, independent of age and sex. Here we performed the C4 test in 58 pediatric patients with Crohn's disease (CD) and ulcerative colitis (UC)., Methods: C4 was measured using high performance liquid chromatography (HPLC) in fasting serum samples of 44 patients with CD (range 7-19 years) and 14 with UC (4-18 years). Disease activity was assessed by the pediatric CD and UC activity indices (PCDAI and PUCAI, respectively) plus serum (CRP, ESR) and fecal inflammatory markers (calprotectin)., Results: C4 concentrations were increased in 10 CD (23%) (range: 70.8-269.3 ng/mL) but only one UC patient (72.9 ng/mL). CD patients with diarrhea (n=12) had higher C4-values compared to those without (76.9 vs. 30.4 ng/mL; p=0.0043). Ileal resection in CD patients (n=10) was associated with increased C4 concentrations (81.2 vs. 24.3 ng/mL, p=0.0004). No correlation was found between C4 values and inflammatory markers. Six of 7 CD patients with persistent diarrhea but quiescent disease (PCDAI ≤12.5) had C4 values indicating BAM., Conclusion: Elevated C4 concentrations indicating BAM are common in children with CD. They are associated with ileal resection and non-bloody diarrhea in the absence of active disease or elevated inflammatory markers. The C4-test identifies a subgroup of CD patients with persistent diarrhea in spite of clinical remission which may benefit from bile acid binding therapy., (Copyright © 2014 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.)

Objective: To establish age-related reference values for 7-alpha-hydroxy-4-cholesten-3-one (C4) in a pediatric population and to investigate bile acid malabsorption in children with short bowel syndrome (SBS)., Study Design: Serum was obtained between 8:00 a.m. and 11:00 a.m. from 100 healthy children (52% males, 9 months to 18 years of age) after 10 hours of fasting. Pediatric patients with SBS served as disease controls (n = 12). Following solid-phase extraction and purification, C4 was determined by high-performance liquid chromatography using a ultraviolet detector at a wavelength of 241 nm. The upper limit of normal for C4 concentrations was defined as the mean plus 2 SD of the log-normal distribution., Results: The mean concentration and SD of C4 in healthy children was 22.8 ± 15.8 ng/mL with no relation to age or sex and an upper limit of normal of 66.5 ng/mL. Normal C4 values were found in 97 of 100 healthy children, and all 12 patients with SBS had C4 concentrations above 100 ng/mL (mean 299.6 ± 167.8 ng/mL; range 105.7-562.1 ng/mL, P < .0001 compared with controls)., Conclusions: The determined upper limit of normal for C4 concentration in healthy children corresponds to previously published levels in healthy adults and is independent of age and sex. The consistently elevated C4 concentrations in our patients with SBS confirm the reliability of this noninvasive, nonisotopic method to assess bile acid malabsorption in children., (Copyright © 2013 Mosby, Inc. All rights reserved.)