Sensory neurons promote immune homeostasis in the lung.

Cytokines employ downstream Janus kinases (JAKs) to promote chronic inflammatory diseases. JAK1-dependent type 2 cytokines drive allergic inflammation, and patients with JAK1 gain-of-function (GoF) variants develop atopic dermatitis (AD) and asthma. To explore tissue-specific functions, we inserted a human JAK1 GoF variant (JAK1GoF) into mice and observed the development of spontaneous AD-like skin disease but unexpected resistance to lung inflammation when JAK1GoF expression was restricted to the stroma. We identified a previously unrecognized role for JAK1 in vagal sensory neurons in suppressing airway inflammation. Additionally, expression of Calcb/CGRPß was dependent on JAK1 in the vagus nerve, and CGRPß suppressed group 2 innate lymphoid cell function and allergic airway inflammation. Our findings reveal evolutionarily conserved but distinct functions of JAK1 in sensory neurons across tissues. This biology raises the possibility that therapeutic JAK inhibitors may be further optimized for tissue-specific efficacy to enhance precision medicine in the future.

Human MCTS1-dependent translation of JAK2 is essential for IFN-γ immunity to mycobacteria.

Human inherited disorders of interferon-gamma (IFN-γ) immunity underlie severe mycobacterial diseases. We report X-linked recessive MCTS1 deficiency in men with mycobacterial disease from kindreds of different ancestries (from China, Finland, Iran, and Saudi Arabia). Complete deficiency of this translation re-initiation factor impairs the translation of a subset of proteins, including the kinase JAK2 in all cell types tested, including T lymphocytes and phagocytes. JAK2 expression is sufficiently low to impair cellular responses to interleukin-23 (IL-23) and partially IL-12, but not other JAK2-dependent cytokines. Defective responses to IL-23 preferentially impair the production of IFN-γ by innate-like adaptive mucosal-associated invariant T cells (MAIT) and γδ T lymphocytes upon mycobacterial challenge. Surprisingly, the lack of MCTS1-dependent translation re-initiation and ribosome recycling seems to be otherwise physiologically redundant in these patients. These findings suggest that X-linked recessive human MCTS1 deficiency underlies isolated mycobacterial disease by impairing JAK2 translation in innate-like adaptive T lymphocytes, thereby impairing the IL-23-dependent induction of IFN-γ.

Human TBK1 deficiency leads to autoinflammation driven by TNF-induced cell death.

TANK binding kinase 1 (TBK1) regulates IFN-I, NF-κB, and TNF-induced RIPK1-dependent cell death (RCD). In mice, biallelic loss of TBK1 is embryonically lethal. We discovered four humans, ages 32, 26, 7, and 8 from three unrelated consanguineous families with homozygous loss-of-function mutations in TBK1. All four patients suffer from chronic and systemic autoinflammation, but not severe viral infections. We demonstrate that TBK1 loss results in hypomorphic but sufficient IFN-I induction via RIG-I/MDA5, while the system retains near intact IL-6 induction through NF-κB. Autoinflammation is driven by TNF-induced RCD as patient-derived fibroblasts experienced higher rates of necroptosis in vitro, and CC3 was elevated in peripheral blood ex vivo. Treatment with anti-TNF dampened the baseline circulating inflammatory profile and ameliorated the clinical condition in vivo. These findings highlight the plasticity of the IFN-I response and underscore a cardinal role for TBK1 in the regulation of RCD.

Mapping Systemic Inflammation and Antibody Responses in Multisystem Inflammatory Syndrome in Children (MIS-C).

Initially, children were thought to be spared from disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a month into the epidemic, a novel multisystem inflammatory syndrome in children (MIS-C) emerged. Herein, we report on the immune profiles of nine MIS-C cases. All MIS-C patients had evidence of prior SARS-CoV-2 exposure, mounting an antibody response with intact neutralization capability. Cytokine profiling identified elevated signatures of inflammation (IL-18 and IL-6), lymphocytic and myeloid chemotaxis and activation (CCL3, CCL4, and CDCP1), and mucosal immune dysregulation (IL-17A, CCL20, and CCL28). Immunophenotyping of peripheral blood revealed reductions of non-classical monocytes, and subsets of NK and T lymphocytes, suggesting extravasation to affected tissues. Finally, profiling the autoantigen reactivity of MIS-C plasma revealed both known disease-associated autoantibodies (anti-La) and novel candidates that recognize endothelial, gastrointestinal, and immune-cell antigens. All patients were treated with anti-IL-6R antibody and/or IVIG, which led to rapid disease resolution.

Human T-bet Governs Innate and Innate-like Adaptive IFN-γ Immunity against Mycobacteria.

Inborn errors of human interferon gamma (IFN-γ) immunity underlie mycobacterial disease. We report a patient with mycobacterial disease due to inherited deficiency of the transcription factor T-bet. The patient has extremely low counts of circulating Mycobacterium-reactive natural killer (NK), invariant NKT (iNKT), mucosal-associated invariant T (MAIT), and Vδ2+ γδ T lymphocytes, and of Mycobacterium-non reactive classic TH1 lymphocytes, with the residual populations of these cells also producing abnormally small amounts of IFN-γ. Other lymphocyte subsets develop normally but produce low levels of IFN-γ, with the exception of CD8+ αß T and non-classic CD4+ αß TH1∗ lymphocytes, which produce IFN-γ normally in response to mycobacterial antigens. Human T-bet deficiency thus underlies mycobacterial disease by preventing the development of innate (NK) and innate-like adaptive lymphocytes (iNKT, MAIT, and Vδ2+ γδ T cells) and IFN-γ production by them, with mycobacterium-specific, IFN-γ-producing, purely adaptive CD8+ αß T, and CD4+ αß TH1∗ cells unable to compensate for this deficit.

A non-canonical function of OAS1 to combat viral and bacterial infections.

The interferon-stimulated gene OAS1 has well-defined antiviral properties. In two recent issues of Immunity, Harioudh et al. describe a non-canonical function of OAS1 that selectively protects the translation of proteins involved in defense against viral or bacterial infections.

Excessive negative regulation of type I interferon disrupts viral control in individuals with Down syndrome.

Down syndrome (DS) is typically caused by triplication of chromosome 21. Phenotypically, DS presents with developmental, neurocognitive, and immune features. Epidemiologically, individuals with DS have less frequent viral infection, but when present, these infections lead to more severe disease. The potent antiviral cytokine type I Interferon (IFN-I) receptor subunits IFNAR1 and IFNAR2 are located on chromosome 21. While increased IFNAR1/2 expression initially caused hypersensitivity to IFN-I, it triggered excessive negative feedback. This led to a hypo-response to subsequent IFN-I stimuli and an ensuing viral susceptibility in DS compared to control cells. Upregulation of IFNAR2 expression phenocopied the DS IFN-I dynamics independent of trisomy 21. CD14+ monocytes from individuals with DS exhibited markers of prior IFN-I exposure and had muted responsiveness to ex vivo IFN-I stimulation. Our findings unveil oscillations of hyper- and hypo-response to IFN-I in DS, predisposing individuals to both lower incidence of viral disease and increased infection-related morbidity and mortality.

Inborn errors of immunity: an expanding universe of disease and genetic architecture.

Inborn errors of immunity (IEIs) are generally considered to be rare monogenic disorders of the immune system that cause immunodeficiency, autoinflammation, autoimmunity, allergy and/or cancer. Here, we discuss evidence that IEIs need not be rare disorders or exclusively affect the immune system. Namely, an increasing number of patients with IEIs present with severe dysregulations of the central nervous, digestive, renal or pulmonary systems. Current challenges in the diagnosis of IEIs that result from the segregated practice of specialized medicine could thus be mitigated, in part, by immunogenetic approaches. Starting with a brief historical overview of IEIs, we then discuss the technological advances that are facilitating the immunogenetic study of IEIs, progress in understanding disease penetrance in IEIs, the expanding universe of IEIs affecting distal organ systems and the future of genetic, biochemical and medical discoveries in this field.

Complex Autoinflammatory Syndrome Unveils Fundamental Principles of JAK1 Kinase Transcriptional and Biochemical Function.

Autoinflammatory disease can result from monogenic errors of immunity. We describe a patient with early-onset multi-organ immune dysregulation resulting from a mosaic, gain-of-function mutation (S703I) in JAK1, encoding a kinase essential for signaling downstream of >25 cytokines. By custom single-cell RNA sequencing, we examine mosaicism with single-cell resolution. We find that JAK1 transcription was predominantly restricted to a single allele across different cells, introducing the concept of a mutational "transcriptotype" that differs from the genotype. Functionally, the mutation increases JAK1 activity and transactivates partnering JAKs, independent of its catalytic domain. S703I JAK1 is not only hypermorphic for cytokine signaling but also neomorphic, as it enables signaling cascades not canonically mediated by JAK1. Given these results, the patient was treated with tofacitinib, a JAK inhibitor, leading to the rapid resolution of clinical disease. These findings offer a platform for personalized medicine with the concurrent discovery of fundamental biological principles.

Autoimmunity in Down's syndrome via cytokines, CD4 T cells and CD11c+ B cells.

Down's syndrome (DS) presents with a constellation of cardiac, neurocognitive and growth impairments. Individuals with DS are also prone to severe infections and autoimmunity including thyroiditis, type 1 diabetes, coeliac disease and alopecia areata1,2. Here, to investigate the mechanisms underlying autoimmune susceptibility, we mapped the soluble and cellular immune landscape of individuals with DS. We found a persistent elevation of up to 22 cytokines at steady state (at levels often exceeding those in patients with acute infection) and detected basal cellular activation: chronic IL-6 signalling in CD4 T cells and a high proportion of plasmablasts and CD11c+TbethighCD21low B cells (Tbet is also known as TBX21). This subset is known to be autoimmune-prone and displayed even greater autoreactive features in DS including receptors with fewer non-reference nucleotides and higher IGHV4-34 utilization. In vitro, incubation of naive B cells in the plasma of individuals with DS or with IL-6-activated T cells resulted in increased plasmablast differentiation compared with control plasma or unstimulated T cells, respectively. Finally, we detected 365 auto-antibodies in the plasma of individuals with DS, which targeted the gastrointestinal tract, the pancreas, the thyroid, the central nervous system, and the immune system itself. Together, these data point to an autoimmunity-prone state in DS, in which a steady-state cytokinopathy, hyperactivated CD4 T cells and ongoing B cell activation all contribute to a breach in immune tolerance. Our findings also open therapeutic paths, as we demonstrate that T cell activation is resolved not only with broad immunosuppressants such as Jak inhibitors, but also with the more tailored approach of IL-6 inhibition.

The immune system in Down Syndrome: Autoimmunity and severe infections.

Over 200,000 individuals in the United States alone live with Down Syndrome (DS), the most common genetic disorder associated with intellectual disability. DS has a constellation of features across the body, including dysregulation of the immune system. Individuals with DS have both a higher frequency of autoimmunity and more severe infections than the general population, highlighting the importance of understanding the immune system in this population. Individuals with DS present with dysregulation of both the innate and adaptive immune systems. Elevated cytokine levels, increased type I and type II IFN signaling, a shift toward memory phenotypes in T cells, and a decrease in the size of the B-cell compartment are observed in individuals with DS, which contribute to both autoinflammation and severe infections. Herein, we discuss the current knowledge of the immune system in individuals with Down Syndrome as well as ideas of necessary further investigations to decipher the mechanisms by which trisomy 21 leads to immune dysregulation, with the ultimate goal of identifying clinical targets to improve treatment.

Dysregulation of the Immune System in a Natural History Study of 1299 Individuals with Down Syndrome.

Dysregulation of the immune system in individuals with Down syndrome is thought to play a major role in the pathophysiology of many clinical presentations. This natural history of disease study took a comprehensive evaluation of the prevalence of different immune related diagnoses in a cohort of 1299 patients with Down syndrome compared to a 2605 patient control cohort at the Mount Sinai Health System in New York, NY over the past 18 years. We conducted a stepwise analysis of the odds of receiving a diagnosis at the Chapter, Sub-chapter and Diagnosis level of the ICD-CM-10 code system. Individuals in our Down syndrome cohort had higher odds of a diagnosis with inflammatory and autoimmune presentations such as Alopecia areata (OR 6.06, p = 0.01), Other sepsis (OR 4.79, p < 0.001, Purpura and other hemorrhagic conditions (OR 2.31, p < 0.001), and Rosacea (OR 3.11, p < 0.001). They also presented with lower odds of a diagnosis of Herpesviral infection (OR 0.42, p = 0.01), and Viral warts (OR 0.51, p = 0.04). We posit that dysregulation of the immune system in individuals with Down syndrome has impact on infectious diseases, including lowering the incidence of viral disease and increasing its severity. Our data also suggests inflammation and autoimmune mediated diseases, in particular of the skin, are exacerbated in individuals with Down syndrome. Finally, there may be a need for greater clinical attention to non-emergent conditions within the Down syndrome patient population as those can also greatly affect quality of life.

Exclusive Characteristics of the p.E555K Dominant-Negative Variant in Autosomal Dominant E47 Deficiency.

PURPOSE: Transcription factor 3 (TCF3) encodes 2 transcription factors generated by alternative splicing, E12 and E47, which contribute to early lymphocyte differentiation. In humans, autosomal dominant (AD) E47 transcription factor deficiency is an inborn error of immunity characterized by B-cell deficiency and agammaglobulinemia. Only the recurrent de novo p.E555K pathogenic variant has been associated with this disease and acts via a dominant-negative (DN) mechanism. In this study, we describe the first Asian patient with agammaglobulinemia caused by the TCF3 p.E555K variant and provide insights into the structure and function of this variant. METHODS: TCF3 variant was identified by inborn errors of immunity-related gene panel sequencing. The variant E555K was characterized by alanine scanning of the E47 basic region and comprehensive mutational analysis focused on position 555. RESULTS: The patient was a 25-year-old male with B-cell deficiency, agammaglobulinemia, and mild facial dysmorphic features. We confirmed the diagnosis of AD E47 transcription factor deficiency by identifying a heterozygous missense variant, c.1663 G>A; p.E555K, in TCF3. Alanine scanning of the E47 basic region revealed the structural importance of position 555. Comprehensive mutational analysis focused on position 555 showed that only the glutamate-to-lysine substitution had a strong DN effect. 3D modeling demonstrated that this variant not only abolished hydrogen bonds involved in protein‒DNA interactions, but also inverted the charge on the surface of the E47 protein. CONCLUSIONS: Our study reveals the causative mutation hotspot in the TCF3 DN variant and highlights the weak negative selection associated with the TCF3 gene.

ISG15 deficiency restricts HIV-1 infection.

Type I interferons (IFN-Is) are a group of potent inflammatory and antiviral cytokines. They induce IFN stimulated genes (ISGs), which act as proinflammatory mediators, antiviral effectors, and negative regulators of the IFN-I signaling cascade itself. One such regulator is interferon stimulated gene 15 (ISG15). Humans with complete ISG15 deficiency express persistently elevated levels of ISGs, and consequently, exhibit broad spectrum resistance to viral infection. Here, we demonstrate that IFN-I primed fibroblasts derived from ISG15-deficient individuals are more resistant to infection with single-cycle HIV-1 compared to healthy control fibroblasts. Complementation with both wild-type (WT) ISG15 and ISG15ΔGG (incapable of ISGylation while retaining negative regulation activity) was sufficient to reverse this phenotype, restoring susceptibility to infection to levels comparable to WT cells. Furthermore, CRISPR-edited ISG15ko primary CD4+ T cells were less susceptible to HIV-1 infection compared to cells treated with non-targeting controls. Transcriptome analysis of these CRISPR-edited ISG15ko primary CD4+ T cells recapitulated the ISG signatures of ISG15 deficient patients. Taken together, we document that the increased broad-spectrum viral resistance in ISG15-deficiency also extends to HIV-1 and is driven by a combination of T-cell-specific ISGs, with both known and unknown functions, predicted to target HIV-1 replication at multiple steps.

Immunodeficiency, autoinflammation and amylopectinosis in humans with inherited HOIL-1 and LUBAC deficiency.

We report the clinical description and molecular dissection of a new fatal human inherited disorder characterized by chronic autoinflammation, invasive bacterial infections and muscular amylopectinosis. Patients from two kindreds carried biallelic loss-of-expression and loss-of-function mutations in HOIL1 (RBCK1), a component of the linear ubiquitination chain assembly complex (LUBAC). These mutations resulted in impairment of LUBAC stability. NF-κB activation in response to interleukin 1ß (IL-1ß) was compromised in the patients' fibroblasts. By contrast, the patients' mononuclear leukocytes, particularly monocytes, were hyper-responsive to IL-1ß. The consequences of human HOIL-1 and LUBAC deficiencies for IL-1ß responses thus differed between cell types, consistent with the unique association of autoinflammation and immunodeficiency in these patients. These data suggest that LUBAC regulates NF-κB-dependent IL-1ß responses differently in different cell types.

Inherited deficiency of stress granule ZNFX1 in patients with monocytosis and mycobacterial disease.

Human inborn errors of IFN-γ underlie mycobacterial disease, due to insufficient IFN-γ production by lymphoid cells, impaired myeloid cell responses to this cytokine, or both. We report four patients from two unrelated kindreds with intermittent monocytosis and mycobacterial disease, including bacillus Calmette-Guérin-osis and disseminated tuberculosis, and without any known inborn error of IFN-γ. The patients are homozygous for ZNFX1 variants (p.S959* and p.E1606Rfs*10) predicted to be loss of function (pLOF). There are no subjects homozygous for pLOF variants in public databases. ZNFX1 is a conserved and broadly expressed helicase, but its biology remains largely unknown. It is thought to act as a viral double-stranded RNA sensor in mice, but these patients do not suffer from severe viral illnesses. We analyze its subcellular localization upon overexpression in A549 and HeLa cell lines and upon stimulation of THP1 and fibroblastic cell lines. We find that this cytoplasmic protein can be recruited to or even induce stress granules. The endogenous ZNFX1 protein in cell lines of the patient homozygous for the p.E1606Rfs*10 variant is truncated, whereas ZNFX1 expression is abolished in cell lines from the patients with the p.S959* variant. Lymphocyte subsets are present at normal frequencies in these patients and produce IFN-γ normally. The hematopoietic and nonhematopoietic cells of the patients tested respond normally to IFN-γ. Our results indicate that human ZNFX1 is associated with stress granules and essential for both monocyte homeostasis and protective immunity to mycobacteria.

IL4Rα and IL17A Blockade Rescue Autoinflammation in SOCS1 Haploinsufficiency.

By inhibition of JAK-STAT signaling, SOCS1 acts as a master regulator of the cytokine response across numerous tissue types and cytokine pathways. Haploinsufficiency of SOCS1 has recently emerged as a monogenic immunodysregulatory disease with marked clinical variability. Here, we describe a patient with severe dermatitis, recurrent skin infections, and psoriatic arthritis that harbors a novel heterozygous mutation in SOCS1. The variant, c.202_203delAC, generates a frameshift in SOCS1, p.Thr68fsAla*49, which leads to complete loss of protein expression. Unlike WT SOCS1, Thr68fs SOCS1 fails to inhibit JAK-STAT signaling when expressed in vitro. The peripheral immune signature from this patient was marked by a redistribution of monocyte sub-populations and hyper-responsiveness to multiple cytokines. Despite this broad hyper-response across multiple cytokine pathways in SOCS1 haploinsufficiency, the patient's clinical disease was markedly responsive to targeted IL4Rα- and IL17-blocking therapy. In accordance, the mutant allele was unable to regulate IL4Rα signaling. Further, patient cells were unresponsive to IL4/IL13 while on monoclonal antibody therapy. Together, this study reports a novel SOCS1 mutation and suggests that IL4Rα blockade may serve as an unexpected, but fruitful therapeutic target for some patients with SOCS1 haploinsufficiency.

JAK Inhibitor Therapy in a Child with Inherited USP18 Deficiency.

Deficiency of ubiquitin-specific peptidase 18 (USP18) is a severe type I interferonopathy. USP18 down-regulates type I interferon signaling by blocking the access of Janus-associated kinase 1 (JAK1) to the type I interferon receptor. The absence of USP18 results in unmitigated interferon-mediated inflammation and is lethal during the perinatal period. We describe a neonate who presented with hydrocephalus, necrotizing cellulitis, systemic inflammation, and respiratory failure. Exome sequencing identified a homozygous mutation at an essential splice site on USP18. The encoded protein was expressed but devoid of negative regulatory ability. Treatment with ruxolitinib was followed by a prompt and sustained recovery. (Funded by King Saud University and others.).

Evaluation and validation of an RT-PCR assay for specific detection of monkeypox virus (MPXV).

Monkeypox virus (MPXV) is a zoonotic orthopoxvirus within the Poxviridae family. MPXV is endemic to Central and West Africa. However, the world is currently witnessing an international outbreak with no clear epidemiological links to travel or animal exposure and with ever-increasing numbers of reported cases worldwide. Here, we evaluated and validated a new, sensitive, and specific real-time PCR-assay for MPXV diagnosis in humans and compare the performance of this novel assay against a Food & Drug Administration-cleared pan-Orthopox RT-PCR assay. We determined specificity, sensitivity, and analytic performance of the PKamp™ Monkeypox Virus RT-PCR assay targeting the viral F3L-gene. In addition, we further evaluated MPXV-PCR-positive specimens by viral culture, electron microscopy, and viral inactivation assays. The limit of detection was established at 7.2 genome copies/reaction, and MPXV was successfully identified in 20 clinical specimens with 100% correlation against the reference method with 100% sensitivity and specificity. Our results demonstrated the validity of this rapid, robust, and reliable RT-PCR assay for specific and accurate diagnosis of MPXV infection in human specimens collected both as dry swabs and in viral transport media. This assay has been approved by NYS Department of Health for clinical use.