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Food allergy (FA) is a significant public health issue, propelled by its rapidly increasing prevalence. Its sharp rise into prominence has focused attention on causative environmental factors and their interplay with the immune system in disease pathogenesis. In that regard, there is now substantial evidence that alterations in the gut microbiome early in life shape the host gut mucosal immunity and may play a critical role in the development of FA. These changes may impact key steps in the development of the infant gut microbiome, including its shaping by maternal factors and upon the introduction of solid food (the weaning reaction). These early life changes may have long range effects on host immunity that manifest later in time as disease pathology. Experimental studies have shown that resetting the host intestinal immune responses by treatment with either a healthy fecal microbiota transplantation or defined commensal bacterial taxa can prevent or treat FA. The mechanisms by which these interventions suppress FA include restoration of gut immune regulatory checkpoints, notably the retinoic orphan receptor gamma T (RORγt)(+) regulatory T cells, the epithelial barrier and healthy immunoglobulin A responses to the gut commensals. These findings inform human studies currently in progress that evaluate the role of microbial therapies in FA.

Purpose Patients with heterozygous gain-of-function (GOF) mutations in STAT1 frequently exhibit chronic mucocutaneous candidiasis (CMC), immunodeficiency and autoimmune manifestations. Several treatment options including targeted therapies and hematopoietic stem cell transplantation (HSCT) are available for STAT1 GOF patients but modalities and outcomes are not well established. Herein, we aimed to unravel the effect of ruxolitinib as a bridge therapy in a patient with sporadic STAT1 T385M mutation to manage infections and other disease manifestations. Methods Peripheral blood mononuclear cells were isolated from the patient prior to, during ruxolitinib treatment and 6 months after HSCT. IFN-beta-induced STAT1 phosphorylation/dephosphorylation levels and PMA/ionomycin-stimulated intracellular IL-17A/IFN-gamma production in CD4(+) T cells were evaluated. Differentially expressed genes between healthy controls and the patient prior to, during ruxolitinib treatment and post-transplantation were investigated using Nanostring nCounter Profiling Panel. Results Ruxolitinib provided favorable responses by controlling candidiasis and autoimmune hemolytic anemia in the patient. Dysregulation in STAT1 phosphorylation kinetics improved with ruxolitinib treatment and was completely normalized after transplantation. T(H)17 deficiency persisted after ruxolitinib treatment, but normalized following HSCT. Consistent with the impairment in JAK/STAT signaling, multiple immune related pathways were found to be dysregulated in the patient. At baseline, genes related to type I IFN-related pathways, antigen processing, T-cell and B-cell functions were upregulated, while NK-cell function and cytotoxicity related genes were downregulated. Dysregulated gene expression was partially improved with ruxolitinib treatment and normalized after transplantation. Conclusion Our findings suggest that improved disease management and immune dysregulatory profile can be achieved with ruxolitinib treatment before transplantation and this would be beneficial to reduce the risk of adverse outcome of HSCT.

Summary The steep rise in food allergy (FA) has evoked environmental factors involved in disease pathogenesis, including the gut microbiota, diet, and their metabolites. Early introduction of solid foods synchronizes with the “weaning reaction,” a time during which the microbiota imprints durable oral tolerance. Recent work has shown that children with FA manifest an early onset dysbiosis with the loss of Clostridiales species, which promotes the differentiation of ROR-γt+ regulatory T cells to suppress FA. This process can be reversed in pre-clinical mouse models by targeted bacteriotherapy. Here, we review the dominant tolerance mechanisms enforced by the microbiota to suppress FA and discuss therapeutic intervention strategies that act to recapitulate the early life window of opportunity in stemming the FA epidemic.

Background Food allergy (FA) affects an increasing proportion of children for reasons that remain obscure. Novel disease biomarkers and curative treatment options are strongly needed. Objective We sought to apply untargeted metabolomic profiling to identify pathogenic mechanisms and candidate disease biomarkers in patients with FA. Methods Mass spectrometry–based untargeted metabolomic profiling was performed on serum samples of children with either FA alone, asthma alone, or both FA and asthma, as well as healthy pediatric control subjects. Results In this pilot study patients with FA exhibited a disease-specific metabolomic signature compared with both control subjects and asthmatic patients. In particular, FA was uniquely associated with a marked decrease in sphingolipid levels, as well as levels of a number of other lipid metabolites, in the face of normal frequencies of circulating natural killer T cells. Specific comparison of patients with FA and asthmatic patients revealed differences in the microbiota-sensitive aromatic amino acid and secondary bile acid metabolism. Children with both FA and asthma exhibited a metabolomic profile that aligned with that of FA alone but not asthma. Among children with FA, the history of severe systemic reactions and the presence of multiple FAs were associated with changes in levels of tryptophan metabolites, eicosanoids, plasmalogens, and fatty acids. Conclusions Children with FA have a disease-specific metabolomic profile that is informative of disease mechanisms and severity and that dominates in the presence of asthma. Lower levels of sphingolipids and ceramides and other metabolomic alterations observed in children with FA might reflect the interplay between an altered microbiota and immune cell subsets in the gut.

© 2021 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd. This article has been contributed to by US Government employees and their work is in the public domain in the USA.Background: Biallelic loss-of-function mutations in CARMIL2 cause combined immunodeficiency associated with dermatitis, inflammatory bowel disease (IBD), and EBV-related smooth muscle tumors. Clinical and immunological characterizations of the disease with long-term follow-up and treatment options have not been previously reported in large cohorts. We sought to determine the clinical and immunological features of CARMIL2 deficiency and long-term efficacy of treatment in controlling different disease manifestations. Methods: The presenting phenotypes, long-term outcomes, and treatment responses were evaluated prospectively in 15 CARMIL2-deficient patients, including 13 novel cases. Lymphocyte subpopulations, protein expression, regulatory T (Treg), and circulating T follicular helper (cTFH) cells were analyzed. Three-dimensional (3D) migration assay was performed to determine T-cell shape. Results: Mean age at disease onset was 38 ± 23 months. Main clinical features were skin manifestations (n = 14, 93%), failure to thrive (n = 10, 67%), recurrent infections (n = 10, 67%), allergic symptoms (n = 8, 53%), chronic diarrhea (n = 4, 27%), and EBV-related leiomyoma (n = 2, 13%). Skin manifestations ranged from atopic and seborrheic dermatitis to psoriasiform rash. Patients had reduced proportions of memory CD4+ T cells, Treg, and cTFH cells. Memory B and NK cells were also decreased. CARMIL2-deficient T cells exhibited reduced T-cell proliferation and cytokine production following CD28 co-stimulation and normal morphology when migrating in a high-density 3D collagen gel matrix. IBD was the most severe clinical manifestation, leading to growth retardation, requiring multiple interventional treatments. All patients were alive with a median follow-up of 10.8 years (range: 3–17 years). Conclusion: This cohort provides clinical and immunological features and long-term follow-up of different manifestations of CARMIL2 deficiency.

Oligoarticular juvenile idiopathic arthritis (oligo JIA) is the most common form of chronic inflammatory arthritis in children, yet the cause of this disease remains unknown. To understand immune responses in oligo JIA, we immunophenotyped synovial fluid T cells with flow cytometry, bulk RNA-Seq, single-cell RNA-Seq (scRNA-Seq), DNA methylation studies, and Treg suppression assays. In synovial fluid, CD4+, CD8+, and gamma delta T cells expressed Th1-related markers, whereas Th17 cells were not enriched. Th1 skewing was prominent in CD4+ T cells, including Tregs, and was associated with severe disease. Transcriptomic studies confirmed a Th1 signature in CD4+ T cells from synovial fluid. The regulatory gene expression signature was preserved in Tregs, even those exhibiting Th1 polarization. These Th1-like Tregs maintained Treg-specific methylation patterns and suppressive function, supporting the stability of this Treg population in the joint. Although synovial fluid CD4+ T cells displayed an overall Th1 phenotype, scRNA-Seq uncovered heterogeneous effector and regulatory subpopulations, including IFN-induced Tregs, peripheral helper T cells, and cytotoxic CD4+ T cells. In conclusion, oligo JIA is characterized by Th1 polarization that encompasses Tregs but does not compromise their regulatory identity. Targeting Th1-driven inflammation and augmenting Treg function may represent important therapeutic approaches in oligo JIA. Joint Biology Consortium [P30 AR070253]; NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS) [K08 AR077037, T32 HL007633-35]; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [5T32AI007512-34]; NIAMSUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS) [P30 AR070253, R01 AR075906, R01 AR073201, K08 AR073339]; Fundacion Bechara; Arbuckle Family Fund for Arthritis Research; Rheumatology Research Foundation; Arthritis National Research Foundation; Office of Faculty Development at Boston Children's Hospital Published version We thank the patients and volunteers for participation in this study. We thank Steve Moskowit for support in preparing the graphical abstract for this study. The graphical abstract makes use of images available at Servier Medical Art (https://smart.servier.com).AMJ was supported in part by a microgrant from the Joint Biology Consortium (P30 AR070253). KW is supported by NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) K08 AR077037. JN was funded by T32 HL007633-35. JER was supported by the NIH grant 5T32AI007512-34. PAN was funded by NIAMS awards R01 AR075906, R01 AR073201, P30 AR070253; the Fundacion Bechara; and the Arbuckle Family Fund for Arthritis Research. LAH was funded by NIAMS K08 AR073339, NIAMS P30 AR070253, an Investigator Award of the Rheumatology Research Foundation, an All Arthritis grant from the Arthritis National Research Foundation, and a Career Development Award from the Office of Faculty Development at Boston Children's Hospital.

The steep rise in the incidence and prevalence of food allergy (FA) in the last decades have focused attention of environmental mechanisms which act to promote disease, chief amongst which is the microbiome. Recent studies have now established the presence of pathogenic dysbiosis in FA that could be precipitated by a variety of environmental insults, including amongst others antibiotic usage and the mode of delivery, that acts to subvert the immune regulatory response that enforce tolerance to dietary antigens. A key attribute of this dysbiosis is the loss of Clostridial bacterial species that act to promote the formation of food allergen-specific nascent regulatory T cells in the gut. Significantly, different immunoprotective commensal bacteria, including members of the Clostridiales and Bacteroidales orders act to induce the transcription factor RORγt in nascent Treg cells via an upstream MyD88-dependent mechanism to promote tolerance to dietary antigens. Activation of this axis is disrupted by the dysbiosis, and can be restored by treatment with therapeutic microbiota. These findings highlight the potential for novel microbiota-based approaches to the prevention and treatment of the FA epidemic.

FOXP3 deficiency in mice and in patients with immune dysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome results in fatal autoimmunity by altering regulatory T (T-reg) cells. CD4(+) T cells in patients with IPEX syndrome and Foxp3-deficient mice were analyzed by single-cell cytometry and RNA-sequencing, revealing heterogeneous T-reg-like cells, some very similar to normal T-reg cells, others more distant. Conventional T cells showed no widespread activation or helper T cell bias, but a monomorphic disease signature affected all CD4(+) T cells. This signature proved to be cell extrinsic since it was extinguished in mixed bone marrow chimeric mice and heterozygous mothers of patients with IPEX syndrome. Normal T-reg cells exerted dominant suppression, quenching the disease signature and revealing in mutant T-reg-like cells a small cluster of genes regulated cell-intrinsically by FOXP3, including key homeostatic regulators. We propose a two-step pathogenesis model: cell-intrinsic downregulation of core FOXP3-dependent genes destabilizes T-reg cells, de-repressing systemic mediators that imprint the disease signature on all T cells, furthering T-reg cell dysfunction. Accordingly, interleukin-2 treatment improved the T-reg-like compartment and survival. FOXP3 deficiency leads to dramatic loss of immune homeostasis. This multicenter collaborative group finds that loss of FOXP3 function only disrupts a few core genes, but this unmasks a degree of systemic inflammation, and it is this environment that then strongly perturbs T-reg cells.

Summary Neutrophil extracellular traps (NETs) have been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS) driven by viruses or bacteria, as well as in numerous immune-mediated disorders. Histone citrullination by the enzyme peptidylarginine deiminase 4 (PAD4) and the consequent decondensation of chromatin are hallmarks in the induction of NETs. Nevertheless, additional histone modifications that may govern NETosis are largely overlooked. Herein, we show that histone deacetylases (HDACs) play critical roles in driving NET formation in human and mouse neutrophils. HDACs belonging to the zinc-dependent lysine deacetylases family are necessary to deacetylate histone H3, thus allowing the activity of PAD4 and NETosis. Of note, HDAC inhibition in mice protects against microbial-induced pneumonia and septic shock, decreasing NETosis and inflammation. Collectively, our findings illustrate a new fundamental step that governs the release of NETs and points to HDAC inhibitors as therapeutic agents that may be used to protect against ARDS and sepsis., Graphical abstract, Highlights • Zn-dependent lysine deacetylases govern neutrophil extracellular trap (NET) formation • Class I/IIb HDACs deacetylate histone H3 allowing its citrullination by PAD4 • HDAC inhibition with ricolinostat protects against viral and bacterial pneumonia • In a model of endotoxic shock, ricolinostat inhibits NETosis and dampens inflammation, Molecular biology; Immunology; Cell biology; Functional aspects of cell biology

FOXP3 deficiency in humans with IPEX syndrome and mice results in fatal systemic autoimmunity by altering regulatory T cell (Treg) physiology, but actual cellular and molecular mechanisms of disease are unclear, part because Treg surface markers may be unreliable in disease states. We used deep profiling by flow cytometry, population and single-cell RNAseq to analyze Tregs and conventional (Tconv) CD4+ T lymphocytes in cohorts of IPEX patients with a range of genetic lesions, and in Foxp3-deficient mice. In all patients and mice, heterogeneous Treg-like cells with an active FOXP3 locus were observed, some differing very little from normal Tregs, others more distant. Tconv showed no widespread activation or Th bias. The dominant mark was a monomorphic signature equally affecting all CD4+ T cells, unexpectedly dampening tumor-Treg and cytokine-signaling modules. In mixed bone marrow chimeras, WT Tregs exerted dominant suppression, normalizing the states of mutant Treg and Tconv, extinguishing the disease signature, and revealing a small gene cluster truly regulated, cell-intrinsically, by FOXP3. These results suggest a two-step pathogenesis model, with therapeutic implications: limited downregulation of a few core Treg genes de-represses a systemic mediator(s), which imprints the disease signature on all T cells, and further dampens Treg function.

Systemic juvenile idiopathic arthritis (sJIA) begins with fever, rash, and high-grade systemic inflammation but commonly progresses to a persistent afebrile arthritis. The basis for this transition is unknown. To evaluate a role for lymphocyte polarization, we characterized T cells from patients with acute and chronic sJIA using flow cytometry, mass cytometry, and RNA sequencing. Acute and chronic sJIA each featured an expanded population of activated Tregs uncommon in healthy controls or in children with nonsystemic JIA. In acute sJIA, Tregs expressed IL-17A and a gene expression signature reflecting Th17 polarization. In chronic sJIA, the Th17 transcriptional signature was identified in T effector cells (Teffs), although expression of IL-17A at the protein level remained rare. Th17 polarization was abrogated in patients responding to IL-1 blockade. These findings identify evolving Th17 polarization in sJIA that begins in Tregs and progresses to Teffs, likely reflecting the impact of the cytokine milieu and consistent with a biphasic model of disease pathogenesis. The results support T cells as a potential treatment target in sJIA.

Background Oral immunotherapy (OIT) successfully desensitizes patients with food allergies, but the immune mechanisms mediating its efficacy remain obscure. Objectives We tested the hypothesis that allergen-specific regulatory T (Treg) cell function is impaired in food allergy and is restored by anti-IgE antibody (omalizumab)-supplemented OIT. Methods Peanut-specific T effector (Teff) and Treg cell proliferative responses, activation markers and cytokine expression were analysed by flow cytometry in 13 peanut-allergic subjects before the start of omalizumab-supplemented OIT and periodically in some subjects thereafter for up to 2 years. Peripheral blood regulatory T cells (Treg cells) were analysed for their peanut-specific suppressor function before and at 1 year following OIT. This study was registered on ClinicalTrials.gov (NCT01290913). Results Proliferation of allergen-specific Teff and Treg cells precipitously declined following the initiation of omalizumab therapy prior to OIT, followed by partial recovery after the initiation of OIT. At baseline, peanut-specific Treg cells exhibited a Th2 cell-like phenotype, characterized by increased IL-4 expression, which progressively reversed upon OIT. Peanut-specific Treg cell suppressor activity was absent at the start of omalizumab/OIT therapy but became robust following OIT. Absent peanut-specific Treg cell function could also be recovered by the acute blockade of IL-4/IL-4R receptor signalling in Treg cells, which inhibited their IL-4 production. Conclusions and clinical relevance OIT supplemented by omalizumab promotes allergen desensitization through an initial omalizumab-dependent step that acutely depletes allergen-reactive T cells, followed by an increase in allergen-specific Treg cell activity due to the reversal of their Th2 cell-like programme. Improved Treg cell function may be a key mechanism by which OIT ameliorates food allergy.

Mutations in Wiskott–Aldrich syndrome protein (WASP) cause autoimmune sequelae including colitis. Yet, how WASP mediates mucosal homeostasis is not fully understood. Here we show that WASP-mediated regulation of anti-inflammatory macrophages is critical for mucosal homeostasis and immune tolerance. The generation and function of anti-inflammatory macrophages are defective in both human and mice in the absence of WASP. Expression of WASP specifically in macrophages, but not in dendritic cells, is critical for regulation of colitis development. Importantly, transfer of WT anti-inflammatory macrophages prevents the development of colitis. DOCK8-deficient macrophages phenocopy the altered macrophage properties associated with WASP deficiency. Mechanistically, we show that both WASP and DOCK8 regulates macrophage function by modulating IL-10-dependent STAT3 phosphorylation. Overall, our study indicates that anti-inflammatory macrophage function and mucosal immune tolerance require both WASP and DOCK8, and that IL-10 signalling modulates a WASP-DOCK8 complex., Deficiency in Wiskott-Aldrich syndrome protein (WASP) has been associated with autoimmune colitis, but the underlying mechanism is still unclear. Here the authors show that WASP deficiency is associated with defective WASP/DOCK8 complex formation, altered IL-10 signalling, and impaired anti-inflammatory macrophage functions.

Background Combined immunodeficiencies (CIDs) are diseases of defective adaptive immunity with diverse clinical phenotypes. Although CIDs are more prevalent in the Middle East than Western countries, the resources for genetic diagnosis are limited. Objectives This study aims to characterize the categories of patients with CIDs in Iran clinically and genetically. Methods Clinical and laboratory data were obtained from 696 patients with CIDs. Patients were subdivided into those with syndromic (344 patients) and nonsyndromic (352 patients) CIDs. Targeted DNA sequencing was performed on 243 (34.9%) patients. Results The overall diagnostic yield of the 243 sequenced patients was 77.8% (189 patients). The clinical diagnosis of hyper-IgE syndrome ( P P = .02), and absence of multiple affected family members ( P = .04) were significantly more frequent in the patients without a genetic diagnosis. An autosomal recessive disease was found in 62.9% of patients, reflecting the high rate of consanguinity in this cohort. Mutations impairing VDJ recombination and DNA repair were the most common underlying causes of CIDs. However, in patients with syndromic CIDs, autosomal recessive mutations in ataxia-telangiectasia mutated (ATM) , autosomal dominant mutations in signal transducer and activator of transcription 3 (STAT3) , and microdeletions in 22q11.21 were the most commonly affected genomic loci. Patients with syndromic CIDs had a significantly lower 5-year survival rate rather than those with nonsyndromic CIDs. Conclusions This study provides proof of principle for the application of targeted next-generation sequencing panels in countries with limited diagnostic resources. The effect of genetic diagnosis on clinical care requires continued improvements in therapeutic resources for these patients.

Beginning in 1970, a committee was constituted under the auspices of the World Health Organization (WHO) to catalog primary immunodeficiencies. Twenty years later, the International Union of Immunological Societies (IUIS) took the remit of this committee. The current report details the categorization and listing of 354 (as of February 2017) inborn errors of immunity. The growth and increasing complexity of the field have been impressive, encompassing an increasing variety of conditions, and the classification described here will serve as a critical reference for immunologists and researchers worldwide.

The mechanisms by which regulatory T (Treg) cells differentially control allergic and autoimmune responses remain unclear. We show that Treg cells in food allergy (FA) had decreased expression of transforming growth factor beta 1 (TGF-β1) because of interleukin-4 (IL-4)- and signal transducer and activator of transciription-6 (STAT6)-dependent inhibition of Tgfb1 transcription. These changes were modeled by Treg cell-specific Tgfb1 monoallelic inactivation, which induced allergic dysregulation by impairing microbiota-dependent retinoic acid receptor-related orphan receptor gamma t (ROR-γt)+ Treg cell differentiation. This dysregulation was rescued by treatment with Clostridiales species, which upregulated Tgfb1 expression in Treg cells. Biallelic deficiency precipitated fatal autoimmunity with intense autoantibody production and dysregulated T follicular helper and B cell responses. These results identify a privileged role of Treg cell-derived TGF-β1 in regulating allergy and autoimmunity at distinct checkpoints in a Tgfb1 gene dose- and microbiota-dependent manner.

Inflammatory conditions are increasingly described in patients with primary immunodeficiencies; however, little is known about the prevalence of immune defects in patients who present first with autoimmunity. We describe the immunologic features of children with early-onset/polyautoimmunity followed in the Multiple Autoimmunity and Immunodeficiency (MAID) Clinic, where patients are co-managed by rheumatologists and immunologists. The most common autoimmune manifestations were cytopenias, lymphoproliferation, and colitis. Recurrent infections were noted in 65% of patients. Abnormalities in lymphocyte subsets and immunoglobulins were common. A pathogenic variant was identified in 19% of patients, and 2 novel inherited disorders were discovered. Additionally, 42% of patients had treatment changes implemented in the MAID clinic. By evaluating this unique cohort of patients, we report on the immunologic underpinning of early-onset/polyautoimmunity. The high rate of genetic diagnoses and treatment interventions in this population highlights the value of collaboration between rheumatologists and immunologists in the care of these complex patients.

BackgroundFood allergy (FA) affects an increasing proportion of children for reasons that remain obscure. Identification of pathogenic mechanisms involved in FA using untargeted metabolomic approaches may provide much needed diagnostic and prognostic disease biomarkers and improved treatment options.MethodsMass spectrometry-based untargeted metabolomic profiling was performed on serum samples of children with either FA alone, asthma alone or both FA and asthma as well as healthy pediatric controls.ResultsFA subjects exhibited a disease-specific metabolomic signature as compared to both control subjects and asthmatics. In particular, FA was uniquely associated with a marked decrease in sphingolipids, as well as a number of other lipid metabolites, in the face of normal frequencies of circulating natural killer T (NKT) cells. Specific comparison of FA and asthmatic subjects revealed differences in the microbiota-sensitive aromatic amino acid and secondary bile acid metabolism. Children with both FA and asthma exhibited a metabolomic profile that aligned with that of FA alone but not asthma. Among children with FA, distinct profiles were associated with history of severe reactions and presence of multiple FA.ConclusionsChildren with FA display a disease-specific metabolomic profile that is informative of disease mechanisms and severity, and which dominates in the presence of asthma. Lower levels of sphingolipids and ceramides and other metabolomic alterations observed in FA children may reflect the interplay between an altered microbiota and immune cell subsets in the gut.

The incidence of food allergy, a disease characterized by adverse immune responses that can render common foods life-threatening, is rising. Yet our current standard of care is simply avoidance of allergenic foods and administration of emergency medications upon accidental exposure. Significant advances have been made in food allergy oral immunotherapy, which is emerging as a potential preventive and curative treatment for this disease. The fundamental strategy of oral immunotherapy is to mitigate adverse immune responses to allergenic food proteins through repeated exposure; reduced reactivity to food allergens (desensitization) often results, but the establishment of sustained immune unresponsiveness or of permanent resolution (tolerance) is not certain. This review examines exciting recent developments in oral immunotherapy for food allergy.

Idiopathic pulmonary fibrosis is a fatal lung disease with a median survival of 2 to 5 years. A decade of studies has downplayed inflammation contributing to its pathogenesis. However, these studies preceded the discovery of regulatory T cells (Tregs) and all of their functions. On the basis of human studies demonstrating Tregs can decrease graft- versus -host disease and vasculitides, there is consideration of their use to treat idiopathic pulmonary fibrosis. We hypothesized that Treg therapy would attenuate the fibroplasia involved in a preclinical murine model of pulmonary fibrosis. IL-2 complex was used in vivo to expand CD4 + CD25 hi Foxp3 + cells in the lung during intratracheal bleomycin challenge; however, this unexpectedly led to an increase in lung fibrosis. More important, this increase in fibrosis was a lymphocyte-dependent process. We corroborated these results using a CD4 + CD25 hi Foxp3 + cellular-based therapy. Mechanistically, we demonstrated that CD4 + CD25 hi Foxp3 + cells undergo alterations during bleomycin challenge and the IL-2 complex had no effect on profibrotic (eg, transforming growth factor-β) or type 17 immune response cytokines; however, there was a marked down-regulation of the type 1 and augmentation of the type 2 immune response cytokines from the lungs. Collectively, our animal studies show that a specific lung injury can induce Treg alterations, which can augment pulmonary fibrosis.

Atopic dermatitis (AD) affects up to 20% of children worldwide and is an increasing public health problem, particularly in developed countries. Although AD in infants and young children can resolve, there is a well-recognized increased risk of sequential progression from AD to other atopic diseases, including food allergy (FA), allergic rhinitis, allergic asthma, and allergic rhinoconjunctivitis, a process referred to as the atopic march. The mechanisms underlying the development of AD and subsequent progression to other atopic comorbidities, particularly FA, are incompletely understood and the subject of intense investigation. Other major research objectives are the development of effective strategies to prevent AD and FA, as well as therapeutic interventions to inhibit the atopic march. In 2017, the Division of Allergy, Immunology, and Transplantation of the National Institute of Allergy and Infectious Diseases sponsored a workshop to discuss current understanding and important advances in these research areas and to identify gaps in knowledge and future research directions. International and national experts in the field were joined by representatives from several National Institutes of Health institutes. Summaries of workshop presentations, key conclusions, and recommendations are presented herein.

PURPOSE: Human Signal transducer and activator of transcription 1 (STAT1) gain of function (GOF) mutations present with a broad range of manifestations ranging from chronic mucocutaneous candidiasis and autoimmunity to combined immunodeficiency (CID). So far, there is very limited experience with hematopoietic stem cell transplantation (HSCT), as a therapeutic modality in this disorder. Here we describe two patients with heterozygous STAT1 GOF mutations mimicking CID who were treated with HSCT. METHODS: Data on the HSC sources, conditioning regimen, graft versus host disease (GvHD) and anti-microbial prophylaxis, and the post-transplant course including engraftment, GvHD, transplant related complications, infections, chimerism, and survival were evaluated. Pre- and post-transplant immunological studies included enumeration of circulating interferon gamma (IFN-γ) - and interleukin 17 (IL-17)-expressing CD4(+) T cells and analysis of IFN-β-induced STAT1 phosphorylation in patient 1 (P1)’s T cells. RESULTS: P1 was transplanted with cord blood from an HLA identical sibling, and P2 with bone marrow from a fully matched unrelated donor using a reduced toxicity conditioning regimen. While P1 completely recovered from her disease, P2 suffered from systemic CMV disease and secondary graft failure and died due to severe pulmonary involvement and hemorrhage. The dysregulated IFN-γ production, suppressed IL-17 response and enhanced STAT1 phosphorylation previously found in the CD4(+) T cells of P1 were normalized following transplantation. CONCLUSION: HSCT could be an alternative and curative therapeutic option for selected STAT1 GOF mutant patients with progressive life-threatening disease unresponsive to conventional therapy. Morbidity and mortality-causing complications included secondary graft failure, infections and bleeding.

Short Summary The phagocyte respiratory burst is mediated by the phagocyte NADPH oxidase, a multi-protein subunit complex that facilitates production of reactive oxygen species and which is essential for host defence. Monogenic deficiency of individual subunits leads to chronic granulomatous disease (CGD), which is characterized by an inability to make reactive oxygen species, leading to severe opportunistic infections and auto-inflammation. However, not all cases of CGD are due to mutations in previously identified subunits. We recently showed that Eros, a novel and highly conserved ER-resident transmembrane protein, is essential for the phagocyte respiratory burst in mice because it is required for expression of gp91 phox -p22 phox heterodimer, which are the membrane bound components of the phagocyte NADPH oxidase. Eros has a human orthologue, CYBC1 / EROS . We now show that the function of CYBC1/EROS is conserved in human cells and describe a case of CGD secondary to a homozygous CYBC1/EROS mutation that abolishes EROS protein expression. This work demonstrates the fundamental importance of CYBC1/EROS in human immunity and describes a novel cause of CGD.

The role of dysbiosis in food allergy (FA) remains unclear. We found that dysbiotic fecal microbiota in FA infants evolved compositionally over time and failed to protect against FA in mice. Infants and mice with FA had decreased IgA and increased IgE binding to fecal bacteria, indicative of a broader breakdown of oral tolerance than hitherto appreciated. Therapy with Clostridiales species impacted by dysbiosis, either as a consortium or as monotherapy with Subdoligranulum variabile, suppressed FA in mice as did a separate immunomodulatory Bacteroidales consortium. Bacteriotherapy induced expression by regulatory T (Treg) cells of the transcription factor ROR-γt in a MyD88-dependent manner, which was deficient in FA infants and mice and ineffectively induced by their microbiota. Deletion of Myd88 or Rorc in Treg cells abrogated protection by bacteriotherapy. Thus, commensals activate a MyD88/ROR-γt pathway in nascent Treg cells to protect against FA, while dysbiosis impairs this regulatory response to promote disease.

The phagocyte respiratory burst is mediated by the phagocyte NADPH oxidase, a multi-protein subunit complex that facilitates production of reactive oxygen species and which is essential for host defence. Monogenic deficiency of individual subunits leads to chronic granulomatous disease (CGD), which is characterized by an inability to make reactive oxygen species, leading to severe opportunistic infections and auto-inflammation. However, not all cases of CGD are due to mutations in previously identified subunits. We recently showed that Eros, a novel and highly conserved ER-resident transmembrane protein, is essential for the phagocyte respiratory burst in mice because it is required for expression of gp91phox-p22phox heterodimer, which are the membrane bound components of the phagocyte NADPH oxidase. We now show that the function of EROS is conserved in human cells and describe a case of CGD secondary to a homozygous EROS mutation that abolishes EROS protein expression. This work demonstrates the fundamental importance of EROS in human immunity and describes a novel cause of CGD.Clinical ImplicationsChronic granulomatous disease is caused by an inability to make reactive oxygen species via the phagocyte NADPH oxidase. Mutations in C17ORF62/EROS, which controls gp91phox- p22phox abundance, are a novel cause of chronic granulomatous disease.Key MessagesThe murine gene, Eros, is known to regulate abundance of gp91phox-p22phox heterodimer and Eros deficient mice are susceptible to infectionWe show that the function of EROS is conserved in human cells and that a homozygous mutation in EROS causes chronic granulomatous disease

There are now nearly 300 single-gene inborn errors of immunity underlying phenotypes as diverse as infection, malignancy, allergy, auto-immunity, and auto-inflammation. For each of these five categories, a growing variety of phenotypes are ascribed to Primary Immunodeficiency Diseases (PID), making PIDs a rapidly expanding field of medicine. The International Union of Immunological Societies (IUIS) PID expert committee (EC) has published every other year a classification of these disorders into tables, defined by shared pathogenesis and/or clinical consequences. In 2013, the IUIS committee also proposed a more user-friendly, phenotypic classification, based on the selection of key phenotypes at the bedside. We herein propose the revised figures, based on the accompanying 2015 IUIS PID EC classification.

Immunodysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) disorder is an autoimmune disease caused by loss-of-function mutations in the gene encoding the forkhead box P3 (FOXP3) transcription factor. These mutations affect the normal function of circulating regulatory T cells. IPEX is characterized by profound immune dysregulation leading to dermatitis, enteropathy, multiple endocrinopathies and failure to thrive. Different forms of renal injury have also been noted in these patients but these have been described to a very limited extent. Three patients with IPEX with characteristic renal findings and mutations in FOXP3, including one novel mutation, are described. Case presentations are followed by a review of the renal manifestations noted in IPEX and the range of therapeutic options for this disorder. We recommend that IPEX be considered in the differential diagnosis of young children who present with signs of immune dysregulation with a concomitant renal biopsy demonstrating immune complex deposition in a membranous-like pattern and/or interstitial nephritis.

We report the case of a 2-week-old boy who presented with a vesiculopustular, bullous eruption in the setting of autoimmune enteropathy, hypothyroidism, membranous nephropathy, Coombs-positive hemolytic anemia, and persistent eosinophilia. Immunologic testing revealed a deficiency of FOXP3-expressing regulatory T cells, and a diagnosis of immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome was made. Histologic analysis, immunofluorescence, and enzyme-linked immunosorbent assay confirmed the bullous eruption as epidermolysis bullosa acquisita with associated collagen VII autoantibody production. The skin lesions responded to systemic immunosuppressant therapy and have regressed after allogeneic bone marrow transplantation.

It is appreciated that the marked increase in the prevalence of asthma over the past few decades reflects changes in environmental exposures and living conditions associated with modern lifestyles.1 Of particular interest is the documentation of a protective effect of exposures associated with traditional farming, the influence of which has waned with increased urbanization and the advent of mechanized agriculture.2 On small family-based farms where children are reared in close proximity to farm animals and their sheds, increased exposure to the microbial products found in these environments, including lipopolysaccharides, has been associated with protection against asthma.3,4 It remains unclear . . .

Item does not contain fulltext BACKGROUND: Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative immune regulator. Heterozygous CTLA4 germline mutations can cause a complex immune dysregulation syndrome in human subjects. OBJECTIVE: We sought to characterize the penetrance, clinical features, and best treatment options in 133 CTLA4 mutation carriers. METHODS: Genetics, clinical features, laboratory values, and outcomes of treatment options were assessed in a worldwide cohort of CTLA4 mutation carriers. RESULTS: We identified 133 subjects from 54 unrelated families carrying 45 different heterozygous CTLA4 mutations, including 28 previously undescribed mutations. Ninety mutation carriers were considered affected, suggesting a clinical penetrance of at least 67%; median age of onset was 11 years, and the mortality rate within affected mutation carriers was 16% (n = 15). Main clinical manifestations included hypogammaglobulinemia (84%), lymphoproliferation (73%), autoimmune cytopenia (62%), and respiratory (68%), gastrointestinal (59%), or neurological features (29%). Eight affected mutation carriers had lymphoma, and 3 had gastric cancer. An EBV association was found in 6 patients with malignancies. CTLA4 mutations were associated with lymphopenia and decreased T-, B-, and natural killer (NK) cell counts. Successful targeted therapies included application of CTLA-4 fusion proteins, mechanistic target of rapamycin inhibitors, and hematopoietic stem cell transplantation. EBV reactivation occurred in 2 affected mutation carriers after immunosuppression. CONCLUSIONS: Affected mutation carriers with CTLA-4 insufficiency can present in any medical specialty. Family members should be counseled because disease manifestation can occur as late as 50 years of age. EBV- and cytomegalovirus-associated complications must be closely monitored. Treatment interventions should be coordinated in clinical trials.

The dedicator of cytokinesis 8 (DOCK8) deficiency is an autosomal recessive-combined immunodeficiency whose clinical spectra include recurrent infections, autoimmunity, malignancies, elevated serum IgE, eczema, and food allergies. Here, we report on patients with loss of function DOCK8 mutations with profound immune dysregulation suggestive of an immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX)-like disorder. Immunophenotyping of lymphocyte subpopulations and analysis of DOCK8 protein expression were evaluated by flow cytometry. T regulatory (Treg) cells were isolated by cell sorting, and their suppressive activity was analyzed by flow cytometry. Gene mutational analysis was performed by whole-exome and Sanger sequencing. Patient 1 (P1) presented at 10 months of age with chronic severe diarrhea and active colitis in the absence of an infectious trigger, severe eczema with elevated serum IgE, and autoimmune hemolytic anemia, suggestive of an IPEX-related disorder. Whole-exome sequencing revealed a homozygous nonsense mutation in DOCK8 at the DOCK-homology region (DHR)-1 (c.1498C>T; p. R500X). Patient P2, a cousin of P1 who carries the same DOCK8 nonsense mutation, presented with eczema and recurrent ear infections in early infancy, and she developed persistent diarrhea by 3 years of age. Patient P3 presented with lymphoproliferation, severe eczema with allergic dysregulation, and chronic diarrhea with colitis. She harbored a homozygous loss of function DOCK8 mutation (c.2402 –1G→A). Treg cell function was severely compromised by both DOCK8 mutations. DOCK8 deficiency may present severe immune dysregulation with features that may overlap with those of IPEX and other IPEX-like disorders.

Dedicator of cytokinesis 8 (DOCK8) deficiency is a combined immunodeficiency that exemplifies the broad clinical features of primary immunodeficiencies (PIDs), extending beyond recurrent infections to include atopy, autoimmunity and cancer. It is caused by loss of function mutations in DOCK8, encoding a guanine nucleotide exchange factor highly expressed in lymphocytes that regulates the actin cytoskeleton. Additional roles of DOCK8 have also emerged, including regulating MyD88-dependent Toll-like receptor signaling and the activation of the transcription factor STAT3. DOCK8 deficiency impairs immune cell migration, function and survival, and it impacts both innate and adaptive immune responses. Clinically, DOCK8 deficiency is characterized by allergic inflammation as well as susceptibility towards infections, autoimmunity and malignancy. This review details the pathophysiology, clinical features and management of DOCK8 deficiency. It also surveys the recently discovered combined immunodeficiency due to DOCK2 deficiency, highlighting in the process the emerging spectrum of PIDs resulting from DOCK protein family abnormalities.

Regulatory T (Treg) cells that express forkhead box P3 (Foxp3) are pivotal to the maintenance of peripheral immunological tolerance [1–3]. They play a critical role in controlling autoimmunity and limiting tissue destruction and inflammation. Failure of Treg cell differentiation in humans due to loss of function mutations in FOXP3 results in fatal autoimmune lymphoproliferative disease, called immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) [1,2,4]. A similar disease (scurfy phenotype) is also seen in Foxp3 mutant mice [5–8]. Consistent with this role of Foxp3 106in mediating Treg cell phenotypic stability, it has been shown in mice that Foxp3 deficiency does not impair Treg cell development per se, but rather abrogates immunoregulatory function [6,9]. In this chapter, we define methods to study Treg cell generation, phenotype, suppressive capacities, and stability. We also describe how to expand or deplete Treg cell population as well as the different Foxp3-related mouse strains available to study Treg cell biology.

SummaryImmunoglobulin E (IgE) antibodies are known for triggering immediate hypersensitivity reactions such as food anaphylaxis. In this study, we tested whether they might additionally function to amplify nascent antibody and T helper 2 (Th2) cell-mediated responses to ingested proteins and whether blocking IgE would modify sensitization. By using mice harboring a disinhibited form of the IL-4 receptor, we developed an adjuvant-free model of peanut allergy. Mast cells and IgE were required for induction of antibody and Th2-cell-mediated responses to peanut ingestion and they impaired regulatory T (Treg) cell induction. Mast-cell-targeted genetic deletion of the FcεRI signaling kinase Syk or Syk blockade also prevented peanut sensitization. In mice with established allergy, Syk blockade facilitated desensitization and induction of Treg cells, which suppressed allergy when transferred to naive recipients. Our study suggests a key role for IgE in driving Th2 cell and IgE responses while suppressing Treg cells in food allergy.

The autosomal recessive form of the Hyper IgE syndrome (AR-HIES) with dedicator of cytokinesis 8 (DOCK8) deficiency is associated with difficult to treat persistent viral skin infections, including papilloma virus infection. Type I interferons play an important role in the defense against viruses. We examined the effect of therapy with IFN-α 2b in an 11-year old boy with DOCK8 deficiency due to a homozygous splice donor site mutation in DOCK8 intron 40. His unremitting warts showed dramatic response to IFN-α 2b therapy. Immunological studies revealed decreased circulating plasmacytoid dendritic cells (pDCs) and profound deficiency of IFN-α production by his peripheral blood mononuclear cells in response to treatment with CpG oligonucleotides. These findings indicate that underlying pDC deficiency and impaired IFN-α production may predispose to chronic viral infections in DOCK8 deficiency. IFN-α 2b therapy maybe useful in controlling recalcitrant viral infections in these patients.

Food allergy is a rapidly growing public health concern because of its increasing prevalence and life-threatening potential. Animal models of food allergy have emerged as a tool for identifying mechanisms involved in the development of sensitization to normally harmless food allergens, as well as delineating the critical immune components of the effector phase of allergic reactions to food. However, the role animal models might play in understanding human diseases remains contentious. This review summarizes how animal models have provided insights into the etiology of human food allergy, experimental corroboration for epidemiologic findings that might facilitate prevention strategies, and validation for the utility of new therapies for food allergy. Improved understanding of food allergy from the study of animal models together with human studies is likely to contribute to the development of novel strategies to prevent and treat food allergy.

To summarize recent progress in our understanding of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) and IPEX-related disorders.A number of Mendelian disorders of immune dysregulation and autoimmunity have been noted to result from defects in T regulatory cell, development and function. The best characterized of these is IPEX, resulting from mutations affecting FOXP3. A number of other gene defects that affect T regulatory cell function also give rise to IPEX-related phenotypes, including loss-of-function mutations in CD25, STAT5b and ITCH. Recent progress includes the identification of gain-of-function mutations in STAT1 as a cause of an IPEX-like disease, emerging FOXP3 genotype/phenotype relationships in IPEX, and the elucidation of a role for the microbiota in the immune dysregulation associated with regulatory T cell deficiency.An expanding spectrum of genetic defects that compromise T regulatory cell function underlies human disorders of immune dysregulation and autoimmunity. Collectively, these disorders offer novel insights into pathways of peripheral tolerance and their disruption in autoimmunity.

Mutations of the recombinase-activating genes 1 and 2 (RAG1 and RAG2) in humans are associated with a broad range of phenotypes. For patients with severe clinical presentation, hematopoietic stem cell transplantation (HSCT) represents the only curative treatment; however, high rates of graft failure and incomplete immune reconstitution have been observed, especially after unconditioned haploidentical transplantation. Studies in mice have shown that Rag-/-natural killer (NK) cells have a mature phenotype, reduced fitness, and increased cytotoxicity. We aimed to analyze NK cell phenotype and function in patients with mutations in RAG and in non-homologous end joining (NHEJ) genes. Here, we provide evidence that NK cells from these patients have an immature phenotype, with significant expansion of CD56(bright) CD16(-/int) CD57(-cells), yet increased degranulation and high perforin content. Correlation was observed between in vitro recombinase activity of the mutant proteins, NK cell abnormalities, and in vivo clinical phenotype. Addition of serotherapy in the conditioning regimen, with the aim of depleting the autologous NK cell compartment, may be important to facilitate engraftment and immune reconstitution in patients with RAG and NHEJ defects treated by HSCT., Funding for this study was provided in part by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health. This work was also supported by grant 2R01AI100887 from the National Institute of Allergy and Infectious Diseases, National Institutes of Health (to JM). The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does the mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

[This corrects the article on p. 798 in vol. 8, PMID: 28769923.]. ispartof: Frontiers in Immunology vol:8 pages:1244- ispartof: location:Switzerland status: published

Objective To review our current understanding of immunotherapy, the immune mechanisms underlying food allergy, and the methodological advances that are furthering our understanding of the role of immune cells and other molecules in mediating food allergies. Data Sources Literature searches were performed using the following combination of terms: allergy , immunotherapy , food , and mechanisms . Data from randomized clinical studies using state-of-the-art mechanistic tools were prioritized. Study Selections Articles were selected based on their relevance to food allergy. Results Current standard of care for food allergies is avoidance of allergenic foods and the use of epinephrine in case of severe reaction during unintentional ingestion. During the last few decades, great strides have been made in understanding the cellular and molecular mechanisms underlying food allergy, and this information is spearheading the development of exciting new treatments. Conclusion Immunotherapy protocols are effective in desensitizing individuals to specific allergens; however, recurrence of allergic sensitization is common after discontinuation of therapy. Interestingly, in a subset of individuals, immunotherapy is protective against allergens even after discontinuation of immunotherapy. Whether this protection is permanent is currently unknown because of inadequate long-term follow-up data. Research on understanding the underlying mechanisms may assist in modifying protocols to improve outcome and enable sustained unresponsiveness, rather than a temporary relief against food allergies. The cellular changes brought about by immunotherapy are still a black box, but major strides in our understanding are being made at an exciting pace.

Pattern recognition receptors (PRRs), receptors of the innate immune system, are important in interaction with pathogens. Caspase Recruitment Domain-containing protein 9 (CARD9), a member of PRRs, is an intracellular adaptor protein important in fungal defense. CARD9 deficiency causes a rare primary immunodeficiency (PID) characterized by superficial and deep fungal infections. We report a 17 year-old female with a homozygous nonsense mutation in CARD9, who presented with severe cerebral fungal infection of the central nervous system. She was also found to have an heterozygous NLRP12 mutation, which may have had add-on effect on the severity of the infection.

The rise in the prevalence of food allergy over the past decades has focused attention of factors that may impact disease development, most notably the gut microbiota. The gut microbial communities play a crucial role in promoting oral tolerance. Their alteration by such factors as Cesarean section delivery, diet and antibiotics may influence disease development. This review highlights recent progress in our understanding of the role of the gut microbiota in the development of food allergy.Food allergy is associated with alterations in the gut microbiota or dysbiosis early in life that may be predictive of disease persistence versus tolerance acquisition. Evidence for the benefits of adjunct therapy with probiotics for the prevention of food allergies and for potentiating oral immunotherapy remains circumstantial, with further studies needed to validate its use. Studies in murine models of food allergy suggest that microbial therapy with protolerogenic bacteria such as certain Clostridial species holds promise in future applications for prevention or therapy of food allergy.Progress in understanding the role of dysbiosis in food allergy and the factors that promote its development, such as antibiotic therapy, diet, modes of infant delivery, and environmental exposures, offer windows of opportunity for both preventive and therapeutic interventions to stem the rising tide of the food allergy epidemic.

Food allergies (FAs) are a growing epidemic in western countries with poorly defined etiology. Defined as an adverse immune response to common food allergens, FAs present heterogeneously as a single- or multi-organ response that ranges in severity from localized hives and angioedema to systemic anaphylaxis. Current research focusing on epithelial-derived cytokines contends that temporal regulation by these factors impact initial sensitization and persistence of FA responses upon repeated food allergen exposure. Mechanistic understanding of FA draws insight from a myriad of atopic conditions studied in humans and modeled in mice. In this review, we will highlight how epithelial-derived cytokines initiate and then potentiate FAs. We will also review existing evidence of the contribution of other atopic diseases to FA pathogenesis and whether FA symptoms overlap with other atopic diseases.

Loss and gain-of-function (GOF) mutations in human signal transducer and activator of transcription 1 (STAT1) lead to distinct phenotypes. Although recurrent infections are common to both types of STAT1 mutations, GOF mutations are distinguished by chronic mucocutaneous candidiasis and autoimmunity. However, the clinical spectra of STAT1 GOF mutations continue to expand. We here describe two patients with STAT1 GOF mutations presenting early in life with combined immunodeficiency (CID). Clinical data and laboratory findings including immunophenotyping, level of interferon (IFN)-γ/IL-17+ T cells, interferon-induced STAT1 phosphorylation, and JAK inhibitor assays were evaluated. Sequencing of STAT1 gene was performed by Sanger sequencer. Patient 1 (P1) had persistent oral candidiasis and cytomegalovirus (CMV) infection since 2 months of age and later developed cavitary lung lesions due to Mycobacterium tuberculosis. Patient 2 (P2) presented with oral candidiasis and recurrent pneumonia at 4 months of age and subsequently developed CMV pneumonitis. Both patients suffered heterozygous missense mutations in STAT1, leading to deleterious amino acid substitutions in the DNA binding domain (P1: c.1154C > T; p.T385M; P2. c.971G > T; p.C324F). Circulating CD4+ T cells of both patients exhibited increased interferon-γ and decreased IL-17 expression as compared to controls. They also exhibited increased IFN-β and -γ-induced STAT1 phosphorylation that was reversed upon treatment with the JAK kinase inhibitor ruxolitinib. STAT1 GOF mutations may present early in life with CID, consistent with the clinical heterogeneity of the disease. JAK kinase inhibitors may potentially be useful in some patients as adjunct therapy pending definitive treatment with bone marrow transplantation.

Individuals with atopic dermatitis immunized with the small pox vaccine, vaccinia virus (VV), are susceptible to eczema vaccinatum (EV), a potentially fatal disseminated infection. Dysfunction of Forkhead box P3 (FoxP3)-positive regulatory T cells (Treg) has been implicated in the pathogenesis of atopic dermatitis. To test whether Treg deficiency predisposes to EV, we percutaneously VV infected FoxP3-deficient (FoxP3KO) mice, which completely lack FoxP3+ Treg. These animals generated both fewer VV-specific CD8+ effector T cells and IFN-γ–producing CD8+ T cells than controls, had higher viral loads, and exhibited abnormal Th2-polarized responses to the virus. To focus on the consequences of Treg deficiency confined to the skin, we generated mixed CCR4KO FoxP3KO bone marrow (CCR4/FoxP3) chimeras in which skin, but not other tissues or central lymphoid organs, lack Treg. Like FoxP3KO mice, the chimeras had impaired VV-specific effector T cell responses and higher viral loads. Skin cytokine expression was significantly altered in infected chimeras compared with controls. Levels of the antiviral cytokines, type I and II IFNs and IL-12, were reduced, whereas expression of the proinflammatory cytokines, IL-6, IL-10, TGF-β, and IL-23, was increased. Importantly, infection of CCR4/FoxP3 chimeras by a noncutaneous route (i.p.) induced immune responses comparable to controls. Our findings implicate allergic skin inflammation resulting from local Treg deficiency in the pathogenesis of EV.