Venous and arterial thrombosis in patients with VEXAS syndrome

ABSTRACT

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, caused by somatic mutations in UBA1, is an autoinflammatory disorder with diverse systemic manifestations. Thrombosis is a prominent clinical feature of VEXAS syndrome. The risk factors and frequency of thrombosis in VEXAS syndrome are not well described, due to the disease's recent discovery and the paucity of large databases. We evaluated 119 patients with VEXAS syndrome for venous and arterial thrombosis and correlated their presence with clinical outcomes and survival. Thrombosis occurred in 49% of patients, mostly venous thromboembolism (VTE; 41%). Almost two-thirds of VTEs were unprovoked, 41% were recurrent, and 20% occurred despite anticoagulation. The cumulative incidence of VTE was 17% at 1 year from symptom onset and 40% by 5 years. Cardiac and pulmonary inflammatory manifestations were associated with time to VTE. M41L was positively associated specifically with pulmonary embolism by univariate (odds ratio [OR]: 4.58, confidence interval [CI] 1.28-16.21, P = .02) and multivariate (OR: 16.94, CI 1.99-144.3, P = .01) logistic regression. The cumulative incidence of arterial thrombosis was 6% at 1 year and 11% at 5 years. The overall survival of the entire patient cohort at median follow-up time of 4.8 years was 88%, and there was no difference in survival between patients with or without thrombosis (P = .8). Patients with VEXAS syndrome are at high risk of VTE; thromboprophylaxis should administered be in high-risk settings unless strongly contraindicated.

Interrupting an IFN-γ-dependent feedback loop in the syndrome of pyogenic arthritis with pyoderma gangrenosum and acne

OBJECTIVES

To study the molecular pathogenesis of PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) syndrome, a debilitating hereditary autoinflammatory disease caused by dominant mutation in PSTPIP1.

METHODS

Gene knock-out and knock-in mice were generated to develop an animal model. THP1 and retrovirally transduced U937 human myeloid leukaemia cell lines, peripheral blood mononuclear cells, small interfering RNA (siRNA) knock-down, site-directed mutagenesis, cytokine immunoassays, coimmunoprecipitation and immunoblotting were used to study inflammasome activation. Cytokine levels in the skin were evaluated by immunohistochemistry. Responsiveness to Janus kinase (JAK) inhibitors was evaluated ex vivo with peripheral blood mononuclear cells and in vivo in five treatment-refractory PAPA patients.

RESULTS

The knock-in mouse model of PAPA did not recapitulate the human disease. In a human myeloid cell line model, PAPA-associated PSTPIP1 mutations activated the pyrin inflammasome, but not the NLRP3, NLRC4 or AIM2 inflammasomes. Pyrin inflammasome activation was independent of the canonical pathway of pyrin serine dephosphorylation and was blocked by the p.W232A PSTPIP1 mutation, which disrupts pyrin-PSTPIP1 interaction. IFN-γ priming of monocytes from PAPA patients led to IL-18 release in a pyrin-dependent manner. IFN-γ was abundant in the inflamed dermis of PAPA patients, but not patients with idiopathic pyoderma gangrenosum. Ex vivo JAK inhibitor treatment attenuated IFN-γ-mediated pyrin induction and IL-18 release. In 5/5 PAPA patients, the addition of JAK inhibitor therapy to IL-1 inhibition was associated with clinical improvement.

CONCLUSION

PAPA-associated PSTPIP1 mutations trigger a pyrin-IL-18-IFN-γ positive feedback loop that drives PAPA disease activity and is a target for JAK inhibition.

Biallelic human SHARPIN loss of function induces autoinflammation and immunodeficiency

The linear ubiquitin assembly complex (LUBAC) consists of HOIP, HOIL-1 and SHARPIN and is essential for proper immune responses. Individuals with HOIP and HOIL-1 deficiencies present with severe immunodeficiency, autoinflammation and glycogen storage disease. In mice, the loss of Sharpin leads to severe dermatitis due to excessive keratinocyte cell death. Here, we report two individuals with SHARPIN deficiency who manifest autoinflammatory symptoms but unexpectedly no dermatological problems. Fibroblasts and B cells from these individuals showed attenuated canonical NF-κB responses and a propensity for cell death mediated by TNF superfamily members. Both SHARPIN-deficient and HOIP-deficient individuals showed a substantial reduction of secondary lymphoid germinal center B cell development. Treatment of one SHARPIN-deficient individual with anti-TNF therapies led to complete clinical and transcriptomic resolution of autoinflammation. These findings underscore the critical function of the LUBAC as a gatekeeper for cell death-mediated immune dysregulation in humans.

Stable and robust Xi and Y transcriptomes drive cell-type-specific autosomal and Xa responses in vivo and in vitro in four human cell types

Recent in vitro studies of human sex chromosome aneuploidy showed that the Xi ("inactive" X) and Y chromosomes broadly modulate autosomal and Xa ("active" X) gene expression in two cell types. We tested these findings in vivo in two additional cell types. Using linear modeling in CD4+ T cells and monocytes from individuals with one to three X chromosomes and zero to two Y chromosomes, we identified 82 sex-chromosomal and 344 autosomal genes whose expression changed significantly with Xi and/or Y dosage in vivo . Changes in sex-chromosomal expression were remarkably constant in vivo and in vitro across all four cell types examined. In contrast, autosomal responses to Xi and/or Y dosage were largely cell-type-specific, with up to 2.6-fold more variation than sex-chromosomal responses. Targets of the X- and Y-encoded transcription factors ZFX and ZFY accounted for a significant fraction of these autosomal responses both in vivo and in vitro . We conclude that the human Xi and Y transcriptomes are surprisingly robust and stable across the four cell types examined, yet they modulate autosomal and Xa genes - and cell function - in a cell-type-specific fashion. These emerging principles offer a foundation for exploring the wide-ranging regulatory roles of the sex chromosomes across the human body.

Ultra-rare genetic variation in relapsing polychondritis: a whole-exome sequencing study

OBJECTIVE

Relapsing polychondritis (RP) is a systemic inflammatory disease of unknown aetiology. The objective of this study was to examine the contribution of rare genetic variations to RP.

METHODS

We performed a case-control exome-wide rare variant association analysis that included 66 unrelated European American cases with RP and 2923 healthy controls (HC). Gene-level collapsing analysis was performed using Firth's logistics regression. Exploratory pathway analysis was performed using three different methods: Gene Set Enrichment Analysis, sequence kernel association test and higher criticism test. Plasma DCBLD2 levels were measured in patients with RP and HC using ELISA.

RESULTS

In the collapsing analysis, RP was associated with a significantly higher burden of ultra-rare damaging variants in the DCBLD2 gene (7.6% vs 0.1%, unadjusted OR=79.8, p=2.93×10-7). Plasma DCBLD2 protein levels were significantly higher in RP than in HC (median 4.06 ng/µL vs 0.05 ng/µL, p<0.001). The pathway analysis revealed a statistically significant enrichment of genes in the tumour necrosis factor signalling pathway driven by rare damaging variants in RELB, RELA and REL using higher criticism test weighted by eigenvector centrality.

CONCLUSIONS

This study identified specific rare variants in the DCBLD2 gene as a putative genetic risk factor for RP. These findings should be validated in additional patients with RP and supported by future functional experiments.

Early activation of inflammatory pathways in UBA1-mutated hematopoietic stem and progenitor cells in VEXAS

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a pleiotropic, severe autoinflammatory disease caused by somatic mutations in the ubiquitin-like modifier activating enzyme 1 (UBA1) gene. To elucidate VEXAS pathophysiology, we performed transcriptome sequencing of single bone marrow mononuclear cells and hematopoietic stem and progenitor cells (HSPCs) from VEXAS patients. HSPCs are biased toward myeloid (granulocytic) differentiation, and against lymphoid differentiation in VEXAS. Activation of multiple inflammatory pathways (interferons and tumor necrosis factor alpha) occurs ontogenically early in primitive hematopoietic cells and particularly in the myeloid lineage in VEXAS, and inflammation is prominent in UBA1-mutated cells. Dysregulation in protein degradation likely leads to higher stress response in VEXAS HSPCs, which positively correlates with inflammation. TCR usage is restricted and there are increased cytotoxicity and IFN-γ signaling in T cells. In VEXAS syndrome, both aberrant inflammation and myeloid predominance appear intrinsic to hematopoietic stem cells mutated in UBA1.

Spectrum of clonal hematopoiesis in VEXAS syndrome

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is caused by somatic mutations in UBA1 (UBA1mut) and characterized by heterogenous systemic autoinflammation and progressive hematologic manifestations, meeting criteria for myelodysplastic syndrome (MDS) and plasma cell dyscrasias. The landscape of myeloid-related gene mutations leading to typical clonal hematopoiesis (CH) in these patients is unknown. Retrospectively, we screened 80 patients with VEXAS for CH in their peripheral blood (PB) and correlated the findings with clinical outcomes in 77 of them. UBA1mut were most common at hot spot p.M41 (median variant allele frequency [VAF] = 75%). Typical CH mutations cooccurred with UBA1mut in 60% of patients, mostly in DNMT3A and TET2, and were not associated with inflammatory or hematologic manifestations. In prospective single-cell proteogenomic sequencing (scDNA), UBA1mut was the dominant clone, present mostly in branched clonal trajectories. Based on integrated bulk and scDNA analyses, clonality in VEXAS followed 2 major patterns: with either typical CH preceding UBA1mut selection in a clone (pattern 1) or occurring as an UBA1mut subclone or in independent clones (pattern 2). VAF in the PB differed markedly between DNMT3A and TET2 clones (median VAF of 25% vs 1%). DNMT3A and TET2 clones associated with hierarchies representing patterns 1 and 2, respectively. Overall survival for all patients was 60% at 10 years. Transfusion-dependent anemia, moderate thrombocytopenia, and typical CH mutations, each correlated with poor outcome. In VEXAS, UBA1mut cells are the primary cause of systemic inflammation and marrow failure, being a new molecularly defined somatic entity associated with MDS. VEXAS-associated MDS is distinct from classical MDS in its presentation and clinical course.

Variant STAT4 and Response to Ruxolitinib in an Autoinflammatory Syndrome

BACKGROUND

Disabling pansclerotic morphea (DPM) is a rare systemic inflammatory disorder, characterized by poor wound healing, fibrosis, cytopenias, hypogammaglobulinemia, and squamous-cell carcinoma. The cause is unknown, and mortality is high.

METHODS

We evaluated four patients from three unrelated families with an autosomal dominant pattern of inheritance of DPM. Genomic sequencing independently identified three heterozygous variants in a specific region of the gene that encodes signal transducer and activator of transcription 4 (STAT4). Primary skin fibroblast and cell-line assays were used to define the functional nature of the genetic defect. We also assayed gene expression using single-cell RNA sequencing of peripheral-blood mononuclear cells to identify inflammatory pathways that may be affected in DPM and that may respond to therapy.

RESULTS

Genome sequencing revealed three novel heterozygous missense gain-of-function variants in STAT4. In vitro, primary skin fibroblasts showed enhanced interleukin-6 secretion, with impaired wound healing, contraction of the collagen matrix, and matrix secretion. Inhibition of Janus kinase (JAK)-STAT signaling with ruxolitinib led to improvement in the hyperinflammatory fibroblast phenotype in vitro and resolution of inflammatory markers and clinical symptoms in treated patients, without adverse effects. Single-cell RNA sequencing revealed expression patterns consistent with an immunodysregulatory phenotype that were appropriately modified through JAK inhibition.

CONCLUSIONS

Gain-of-function variants in STAT4 caused DPM in the families that we studied. The JAK inhibitor ruxolitinib attenuated the dermatologic and inflammatory phenotype in vitro and in the affected family members. (Funded by the American Academy of Allergy, Asthma, and Immunology Foundation and others.).

TNF-Blockade for Primary Stroke Prevention in Adenosine Deaminase 2 Deficiency: A Case Series

OBJECTIVES

Adenosine deaminase 2 deficiency (DADA2) is a genetic, neurologic, and systemic vasculitis syndrome, which can lead to recurrent strokes, typically lacunar. In the cohort of now 60 patients followed up at the NIH Clinical Center (NIH CC), no patient has had a stroke since starting tumor necrosis factor (TNF) blockade. We present a family with multiple affected children to highlight the importance of TNF blockade not just as secondary stroke prevention but also as primary stroke prevention in genetically affected but clinically asymptomatic patients.

METHODS

A proband with recurrent cryptogenic strokes was referred for evaluation at the NIH CC. The parents and 3 clinically asymptomatic siblings were also evaluated.

RESULTS

The proband was diagnosed with DADA2 based on biochemical testing; her antiplatelet therapies were discontinued, and she was started on TNF blockade for secondary stroke prevention. Her 3 asymptomatic siblings were subsequently tested and 2 were found to be biochemically affected. One of them elected to start TNF blockade for primary stroke prevention and the other sibling declined this approach and experienced a stroke. A second genetic sequence variant was subsequently identified in the ADA2 gene.

DISCUSSION

This family illustrates the importance of testing for DADA2 in young patients with cryptogenic stroke, given the hemorrhagic risks with antiplatelet drugs in these patients and effectiveness of TNF blockade as secondary stroke prevention. In addition, this family highlights the importance of screening all siblings of affected patients because they may be presymptomatic, and we advocate starting TNF blockade for primary stroke prevention in those who are found to be genetically or biochemically affected.

Evaluation and Management of Deficiency of Adenosine Deaminase 2: An International Consensus Statement

Importance

Deficiency of adenosine deaminase 2 (DADA2) is a recessively inherited disease characterized by systemic vasculitis, early-onset stroke, bone marrow failure, and/or immunodeficiency affecting both children and adults. DADA2 is among the more common monogenic autoinflammatory diseases, with an estimate of more than 35 000 cases worldwide, but currently, there are no guidelines for diagnostic evaluation or management.

Objective

To review the available evidence and develop multidisciplinary consensus statements for the evaluation and management of DADA2.

Evidence Review

The DADA2 Consensus Committee developed research questions based on data collected from the International Meetings on DADA2 organized by the DADA2 Foundation in 2016, 2018, and 2020. A comprehensive literature review was performed for articles published prior to 2022. Thirty-two consensus statements were generated using a modified Delphi process, and evidence was graded using the Oxford Center for Evidence-Based Medicine Levels of Evidence.

Findings

The DADA2 Consensus Committee, comprising 3 patient representatives and 35 international experts from 18 countries, developed consensus statements for (1) diagnostic testing, (2) screening, (3) clinical and laboratory evaluation, and (4) management of DADA2 based on disease phenotype. Additional consensus statements related to the evaluation and treatment of individuals with DADA2 who are presymptomatic and carriers were generated. Areas with insufficient evidence were identified, and questions for future research were outlined.

Conclusions and Relevance

DADA2 is a potentially fatal disease that requires early diagnosis and treatment. By summarizing key evidence and expert opinions, these consensus statements provide a framework to facilitate diagnostic evaluation and management of DADA2.

Ultra-Rare Genetic Variation in Relapsing Polychondritis: A Whole-Exome Sequencing Study

Objective

Relapsing polychondritis (RP) is a systemic inflammatory disease of unknown etiology. The study objective was to examine the contribution of rare genetic variations in RP.

Methods

We performed a case-control exome-wide rare variant association analysis including 66 unrelated European American RP cases and 2923 healthy controls. Gene-level collapsing analysis was performed using Firth's logistics regression. Pathway analysis was performed on an exploratory basis with three different methods: Gene Set Enrichment Analysis (GSEA), sequence kernel association test (SKAT) and higher criticism test. Plasma DCBLD2 levels were measured in patients with RP and healthy controls using enzyme-linked immunosorbent assay (ELISA).

Results

In the collapsing analysis, RP was associated with higher burden of ultra-rare damaging variants in the DCBLD2 gene (7.6% vs 0.1%, unadjusted odds ratio = 79.8, p = 2.93 × 10-7). Patients with RP and ultra-rare damaging variants in DCBLD2 had a higher prevalence of cardiovascular manifestations. Plasma DCBLD2 protein levels were significantly higher in RP than healthy controls (5.9 vs 2.3, p < 0.001). Pathway analysis showed statistically significant enrichment of genes in the tumor necrosis factor (TNF) signaling pathway driven by rare damaging variants in RELB, RELA and REL using higher criticism test weighted by degree and eigenvector centrality.

Conclusions

This study identified specific rare variants in DCBLD2 as putative genetic risk factors for RP. Genetic variation within the TNF pathway is also potentially associated with development of RP. These findings should be validated in additional patients with RP and supported by future functional experiments.

Ophthalmic Manifestations of ROSAH (Retinal Dystrophy, Optic Nerve Edema, Splenomegaly, Anhidrosis, and Headache) Syndrome, an Inherited NF κB-Mediated Autoinflammatory Disease with Retinal Dystrophy

PURPOSE

We aimed to characterize the ocular phenotype of patients with ROSAH (retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and headache) syndrome and their response to therapy.

DESIGN

Single-center observational case study.

PARTICIPANTS

Eleven patients with a diagnosis of ROSAH syndrome and mutation in ALPK1 were included.

METHODS

Patients with molecularly confirmed ROSAH syndrome underwent ophthalmic evaluation, including visual acuity testing, slit-lamp and dilated examinations, color fundus and autofluorescence imaging, fluorescein angiography, OCT, and electrophysiologic testing.

MAIN OUTCOME MEASURES

Visual acuity, electrophysiology, fluorescein angiography, and OCT findings.

RESULTS

Eleven individuals (6 female and 5 male patients) from 7 families ranging in age from 7.3 to 60.2 years at the time of the initial evaluation were included in this study. Seven patients were followed up for a mean of 2.6 years (range, 0.33-5.0 years). Best-corrected visual acuity at baseline ranged from 20/16 to no light perception. Variable signs or sequelae of intraocular inflammation were observed in 9 patients, including keratic precipitates, band keratopathy, trace to 2+ anterior chamber cells, cystoid macular edema, and retinal vasculitis on fluorescein angiography. Ten patients were observed to show optic disc elevation and demonstrated peripapillary thickening on OCT. Seven patients showed retinal degeneration consistent with a cone-rod dystrophy, with atrophy tending to involve the posterior pole and extending peripherally. One patient with normal electroretinography findings and visual evoked potential was found to have decreased Arden ratio on electro-oculography.

CONCLUSIONS

Leveraging insights from the largest single-center ROSAH cohort described to date, this study identified 3 main factors as contributing to changes in visual function of patients with ROSAH syndrome: optic nerve involvement; intraocular inflammation, including cystoid macular edema; and retinal degeneration. More work is needed to determine how to arrest the progressive vision loss associated with ROSAH syndrome.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Multiomics integration of 22 immune-mediated monogenic diseases reveals an emergent axis of human immune health

Monogenic diseases are often studied in isolation due to their rarity. Here we utilize multiomics to assess 22 monogenic immune-mediated conditions with age- and sex-matched healthy controls. Despite clearly detectable disease-specific and "pan-disease" signatures, individuals possess stable personal immune states over time. Temporally stable differences among subjects tend to dominate over differences attributable to disease conditions or medication use. Unsupervised principal variation analysis of personal immune states and machine learning classification distinguishing between healthy controls and patients converge to a metric of immune health (IHM). The IHM discriminates healthy from multiple polygenic autoimmune and inflammatory disease states in independent cohorts, marks healthy aging, and is a pre-vaccination predictor of antibody responses to influenza vaccination in the elderly. We identified easy-to-measure circulating protein biomarker surrogates of the IHM that capture immune health variations beyond age. Our work provides a conceptual framework and biomarkers for defining and measuring human immune health.

Estimated Prevalence and Clinical Manifestations of UBA1 Variants Associated With VEXAS Syndrome in a Clinical Population

IMPORTANCE

VEXAS (vacuoles, E1-ubiquitin-activating enzyme, X-linked, autoinflammatory, somatic) syndrome is a disease with rheumatologic and hematologic features caused by somatic variants in UBA1. Pathogenic variants are associated with a broad spectrum of clinical manifestations. Knowledge of prevalence, penetrance, and clinical characteristics of this disease have been limited by ascertainment biases based on known phenotypes.

OBJECTIVE

To determine the prevalence of pathogenic variants in UBA1 and associated clinical manifestations in an unselected population using a genomic ascertainment approach.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective observational study evaluated UBA1 variants in exome data from 163 096 participants within the Geisinger MyCode Community Health Initiative. Clinical phenotypes were determined from Geisinger electronic health record data from January 1, 1996, to January 1, 2022.

EXPOSURES

Exome sequencing was performed.

MAIN OUTCOMES AND MEASURES

Outcome measures included prevalence of somatic UBA1 variation; presence of rheumatologic, hematologic, pulmonary, dermatologic, and other findings in individuals with somatic UBA1 variation on review of the electronic health record; review of laboratory data; bone marrow biopsy pathology analysis; and in vitro enzymatic assays.

RESULTS

In 163 096 participants (mean age, 52.8 years; 94% White; 61% women), 11 individuals harbored likely somatic variants at known pathogenic UBA1 positions, with 11 of 11 (100%) having clinical manifestations consistent with VEXAS syndrome (9 male, 2 female). A total of 5 of 11 individuals (45%) did not meet criteria for rheumatologic and/or hematologic diagnoses previously associated with VEXAS syndrome; however, all individuals had anemia (hemoglobin: mean, 7.8 g/dL; median, 7.5 g/dL), which was mostly macrocytic (10/11 [91%]) with concomitant thrombocytopenia (10/11 [91%]). Among the 11 patients identified, there was a pathogenic variant in 1 male participant prior to onset of VEXAS-related signs or symptoms and 2 female participants had disease with heterozygous variants. A previously unreported UBA1 variant (c.1861A>T; p.Ser621Cys) was found in a symptomatic patient, with in vitro data supporting a catalytic defect and pathogenicity. Together, disease-causing UBA1 variants were found in 1 in 13 591 unrelated individuals (95% CI, 1:7775-1:23 758), 1 in 4269 men older than 50 years (95% CI, 1:2319-1:7859), and 1 in 26 238 women older than 50 years (95% CI, 1:7196-1:147 669).

CONCLUSIONS AND RELEVANCE

This study provides an estimate of the prevalence and a description of the clinical manifestations of UBA1 variants associated with VEXAS syndrome within a single regional health system in the US. Additional studies are needed in unselected and genetically diverse populations to better define general population prevalence and phenotypic spectrum.

Case report: Novel variants in RELA associated with familial Behcet's-like disease

RELA haploinsufficiency is a recently described autoinflammatory condition presenting with intermittent fevers and mucocutaneous ulcerations. The RELA gene encodes the p65 protein, one of five NF-κB family transcription factors. As RELA is an essential regulator of mucosal homeostasis, haploinsufficiency leads to decreased NF-κB signaling which promotes TNF-driven mucosal apoptosis with impaired epithelial recovery. Thus far, only eight cases have been reported in the literature. Here, we report four families with three novel and one previously described pathogenic variant in RELA. These four families included 23 affected individuals for which genetic testing was available in 16. Almost half of these patients had been previously diagnosed with more common rheumatologic entities (such as Behcet's Disease; BD) prior to the discovery of their pathogenic RELA variants. The most common clinical features were orogenital ulcers, rash, joint inflammation, and fever. The least common were conjunctivitis and recurrent infections. Clinical variability was remarkable even among familial cases, and incomplete penetrance was observed. Patients in our series were treated with a variety of medications, and benefit was observed with glucocorticoids, colchicine, and TNF inhibitors. Altogether, our work adds to the current literature and doubles the number of reported cases with RELA-Associated Inflammatory Disease (RAID). It reaffirms the central importance of the NF-κB pathway in immunity and inflammation, as well as the important regulatory role of RELA in mucosal homeostasis. RELA associated inflammatory disease should be considered in all patients with BD, particularly those with early onset and/or with a strong family history.

Galantamine attenuates autoinflammation in a mouse model of familial mediterranean fever

BACKGROUND

Autoinflammatory diseases, a diverse group of inherited conditions characterized by excessive innate immune activation, have limited therapeutic options. Neuroimmune circuits of the inflammatory reflex control innate immune overactivation and can be stimulated to treat disease using the acetylcholinesterase inhibitor galantamine.

METHODS

We tested the efficacy of galantamine in a rodent model of the prototypical autoinflammatory disease familial Mediterranean fever (FMF). Multiple chronic disease markers were evaluated in animals that received long-term galantamine treatment compared to vehicle.

RESULTS

Long-term treatment with galantamine attenuated the associated splenomegaly and anemia which are characteristic features of this disease. Further, treatment reduced inflammatory cell infiltration into affected organs and a subcutaneous air pouch.

CONCLUSIONS

These findings suggest that galantamine attenuates chronic inflammation in this mouse model of FMF. Further research is warranted to explore the therapeutic potential of galantamine in FMF and other autoinflammatory diseases.

Steroid hormone catabolites activate the pyrin inflammasome through a non-canonical mechanism

The pyrin inflammasome acts as a guard of RhoA GTPases and is central to immune defenses against RhoA-manipulating pathogens. Pyrin activation proceeds in two steps. Yet, the second step is still poorly understood. Using cells constitutively activated for the pyrin step 1, a chemical screen identifies etiocholanolone and pregnanolone, two catabolites of testosterone and progesterone, acting at low concentrations as specific step 2 activators. High concentrations of these metabolites fully and rapidly activate pyrin, in a human specific, B30.2 domain-dependent manner and without inhibiting RhoA. Mutations in MEFV, encoding pyrin, cause two distinct autoinflammatory diseases pyrin-associated autoinflammation with neutrophilic dermatosis (PAAND) and familial Mediterranean fever (FMF). Monocytes from PAAND patients, and to a lower extent from FMF patients, display increased responses to these metabolites. This study identifies an unconventional pyrin activation mechanism, indicates that endogenous steroid catabolites can drive autoinflammation, through the pyrin inflammasome, and explains the “steroid fever” described in the late 1950s upon steroid injection in humans.

Magnotti et al. use a chemical screen to identify pyrin inflammasome activators acting primarily on pyrin step 2. Pregnanolone and etiocholanolone, two catabolites of progesterone and testosterone, activate human pyrin in a B30.2-dependent manner. Pyrin-mutated PAAND patients are highly responsive to pregnanolone. These endogenous catabolites could contribute to sterile (auto)inflammation.

Translation of cytoplasmic UBA1 contributes to VEXAS syndrome pathogenesis

Somatic mutations in UBA1 cause vacuoles, E1 ubiquitin-activating enzyme, X-linked, autoinflammatory somatic (VEXAS) syndrome, an adult-onset inflammatory disease with an overlap of hematologic manifestations. VEXAS syndrome is characterized by a high mortality rate and significant clinical heterogeneity. We sought to determine independent predictors of survival in VEXAS and to understand the mechanistic basis for these factors. We analyzed 83 patients with somatic pathogenic variants in UBA1 at p.Met41 (p.Met41Leu/Thr/Val), the start codon for translation of the cytoplasmic isoform of UBA1 (UBA1b). Patients with the p.Met41Val genotype were most likely to have an undifferentiated inflammatory syndrome. Multivariate analysis showed ear chondritis was associated with increased survival, whereas transfusion dependence and the p.Met41Val variant were independently associated with decreased survival. Using in vitro models and patient-derived cells, we demonstrate that p.Met41Val variant supports less UBA1b translation than either p.Met41Leu or p.Met41Thr, providing a molecular rationale for decreased survival. In addition, we show that these 3 canonical VEXAS variants produce more UBA1b than any of the 6 other possible single-nucleotide variants within this codon. Finally, we report a patient, clinically diagnosed with VEXAS syndrome, with 2 novel mutations in UBA1 occurring in cis on the same allele. One mutation (c.121 A>T; p.Met41Leu) caused severely reduced translation of UBA1b in a reporter assay, but coexpression with the second mutation (c.119 G>C; p.Gly40Ala) rescued UBA1b levels to those of canonical mutations. We conclude that regulation of residual UBA1b translation is fundamental to the pathogenesis of VEXAS syndrome and contributes to disease prognosis.

Gain-of-function mutations in ALPK1 cause an NF-κB-mediated autoinflammatory disease: functional assessment, clinical phenotyping and disease course of patients with ROSAH syndrome

Objectives

To test the hypothesis that ROSAH (retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis and headache) syndrome, caused by dominant mutation in ALPK1, is an autoinflammatory disease.

Methods

This cohort study systematically evaluated 27 patients with ROSAH syndrome for inflammatory features and investigated the effect of ALPK1 mutations on immune signalling. Clinical, immunologic and radiographical examinations were performed, and 10 patients were empirically initiated on anticytokine therapy and monitored. Exome sequencing was used to identify a new pathogenic variant. Cytokine profiling, transcriptomics, immunoblotting and knock-in mice were used to assess the impact of ALPK1 mutations on protein function and immune signalling.

Results

The majority of the cohort carried the p.Thr237Met mutation but we also identified a new ROSAH-associated mutation, p.Tyr254Cys.

Nearly all patients exhibited at least one feature consistent with inflammation including recurrent fever, headaches with meningeal enhancement and premature basal ganglia/brainstem mineralisation on MRI, deforming arthritis and AA amyloidosis. However, there was significant phenotypic variation, even within families and some adults lacked functional visual deficits. While anti-TNF and anti-IL-1 therapies suppressed systemic inflammation and improved quality of life, anti-IL-6 (tocilizumab) was the only anticytokine therapy that improved intraocular inflammation (two of two patients).

Patients’ primary samples and in vitro assays with mutated ALPK1 constructs showed immune activation with increased NF-κB signalling, STAT1 phosphorylation and interferon gene expression signature. Knock-in mice with the Alpk1 T237M mutation exhibited subclinical inflammation.

Clinical features not conventionally attributed to inflammation were also common in the cohort and included short dental roots, enamel defects and decreased salivary flow.

Conclusion

ROSAH syndrome is an autoinflammatory disease caused by gain-of-function mutations in ALPK1 and some features of disease are amenable to immunomodulatory therapy.

Human OTULIN haploinsufficiency impairs cell-intrinsic immunity to staphylococcal α-toxin

The molecular basis of interindividual clinical variability upon infection with Staphylococcus aureus is unclear. We describe patients with haploinsufficiency for the linear deubiquitinase OTULIN, encoded by a gene on chromosome 5p. Patients suffer from episodes of life-threatening necrosis, typically triggered by S. aureus infection. The disorder is phenocopied in patients with the 5p- (Cri-du-Chat) chromosomal deletion syndrome. OTULIN haploinsufficiency causes an accumulation of linear ubiquitin in dermal fibroblasts, but tumor necrosis factor receptor-mediated nuclear factor κB signaling remains intact. Blood leukocyte subsets are unaffected. The OTULIN-dependent accumulation of caveolin-1 in dermal fibroblasts, but not leukocytes, facilitates the cytotoxic damage inflicted by the staphylococcal virulence factor α-toxin. Naturally elicited antibodies against α-toxin contribute to incomplete clinical penetrance. Human OTULIN haploinsufficiency underlies life-threatening staphylococcal disease by disrupting cell-intrinsic immunity to α-toxin in nonleukocytic cells.

The 2021 EULAR/American College of Rheumatology points to consider for diagnosis, management and monitoring of the interleukin-1 mediated autoinflammatory diseases: cryopyrin-associated periodic syndromes, tumour necrosis factor receptor-associated periodic syndrome, mevalonate kinase deficiency, and deficiency of the interleukin-1 receptor antagonist

BACKGROUND

The interleukin-1 (IL-1) mediated systemic autoinflammatory diseases, including the cryopyrin-associated periodic syndromes (CAPS), tumour necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD) and deficiency of the IL-1 receptor antagonist (DIRA), belong to a group of rare immunodysregulatory diseases that primarily present in early childhood with variable multiorgan involvement. When untreated, patients with severe clinical phenotypes have a poor prognosis, and diagnosis and management of these patients can be challenging. However, approved treatments targeting the proinflammatory cytokine IL-1 have been life changing and have significantly improved patient outcomes.

OBJECTIVE

To establish evidence-based recommendations for diagnosis, treatment and monitoring of patients with IL-1 mediated autoinflammatory diseases to standardise their management.

METHODS

A multinational, multidisciplinary task force consisting of physician experts, including rheumatologists, patients or caregivers and allied healthcare professionals, was established. Evidence synthesis, including systematic literature review and expert consensus (Delphi) via surveys, was conducted. Consensus methodology was used to formulate and vote on statements to guide optimal patient care.

RESULTS

The task force devised five overarching principles, 14 statements related to diagnosis, 10 on therapy, and nine focused on long-term monitoring that were evidence and/or consensus-based for patients with IL-1 mediated diseases. An outline was developed for disease-specific monitoring of inflammation-induced organ damage progression and reported treatments of CAPS, TRAPS, MKD and DIRA.

CONCLUSION

The 2021 EULAR/American College of Rheumatology points to consider represent state-of-the-art knowledge based on published data and expert opinion to guide diagnostic evaluation, treatment and monitoring of patients with CAPS, TRAPS, MKD and DIRA, and to standardise and improve care, quality of life and disease outcomes.

Disorders of ubiquitylation: unchained inflammation

Ubiquitylation is an essential post-translational modification that regulates intracellular signalling networks by triggering proteasomal substrate degradation, changing the activity of substrates or mediating changes in proteins that interact with substrates. Hundreds of enzymes participate in reversible ubiquitylation of proteins, some acting globally and others targeting specific proteins. Ubiquitylation is essential for innate immune responses, as it facilitates rapid regulation of inflammatory pathways, thereby ensuring sufficient but not excessive responses. A growing number of inborn errors of immunity are attributed to dysregulated ubiquitylation. These genetic disorders exhibit broad clinical manifestations, ranging from susceptibility to infection to autoinflammatory and/or autoimmune features, lymphoproliferation and propensity to malignancy. Many autoinflammatory disorders result from disruption of components of the ubiquitylation machinery and lead to overactivation of innate immune cells. An understanding of the disorders of ubiquitylation in autoinflammatory diseases could enable the development of novel management strategies.

The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort

The deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessively inherited disease that has undergone extensive phenotypic expansion since being first described in patients with fevers, recurrent strokes, livedo racemosa, and polyarteritis nodosa in 2014. It is now recognized that patients may develop multisystem disease that spans multiple medical subspecialties. Here, we describe the findings from a large single center longitudinal cohort of 60 patients, the broad phenotypic presentation, as well as highlight the cohort’s experience with hematopoietic cell transplantation and COVID-19. Disease manifestations could be separated into three major phenotypes: inflammatory/vascular, immune dysregulatory, and hematologic, however, most patients presented with significant overlap between these three phenotype groups. The cardinal features of the inflammatory/vascular group included cutaneous manifestations and stroke. Evidence of immune dysregulation was commonly observed, including hypogammaglobulinemia, absent to low class-switched memory B cells, and inadequate response to vaccination. Despite these findings, infectious complications were exceedingly rare in this cohort. Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients. We significantly extended our experience using anti-TNF agents, with no strokes observed in 2026 patient months on TNF inhibitors. Meanwhile, hematologic and immune features had a more varied response to anti-TNF therapy. Six patients received a total of 10 allogeneic hematopoietic cell transplant (HCT) procedures, with secondary graft failure necessitating repeat HCTs in three patients, as well as unplanned donor cell infusions to avoid graft rejection. All transplanted patients had been on anti-TNF agents prior to HCT and received varying degrees of reduced-intensity or non-myeloablative conditioning. All transplanted patients are still alive and have discontinued anti-TNF therapy. The long-term follow up afforded by this large single-center study underscores the clinical heterogeneity of DADA2 and the potential for phenotypes to evolve in any individual patient.

Excess Serum Interleukin-18 Distinguishes Patients With Pathogenic Mutations in PSTPIP1

OBJECTIVE

Dominantly inherited PSTPIP1 mutations cause a spectrum of autoinflammatory manifestations epitomized by PAPA syndrome (pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome.). The connections between PSTPIP1 and PAPA syndrome are poorly understood, although evidence suggests involvement of pyrin inflammasome activation. Interleukin-18 (IL-18) is an inflammasome-activated cytokine associated with susceptibility to macrophage activation syndrome (MAS). This study was undertaken to investigate an association of IL-18 with PAPA syndrome.

METHODS

Clinical and genetic data and serum samples were obtained from patients referred to institutions due to symptoms indicative of PAPA syndrome. Serum IL-18, IL-18 binding protein (IL-18BP), and CXCL9 levels were assessed by bead-based assay, and free IL-18 levels were assessed by enzyme-linked immunosorbent assay.

RESULTS

The symptoms of PSTPIP1-positive patients with PAPA syndrome overlapped with those of mutation-negative patients with PAPA-like conditions, but mutation-positive patients had earlier onset and a greater proportion had a history of arthritis. We found uniform elevation of total serum IL-18 in treated PAPA syndrome patients at levels nearly as high as those seen in NLRC4-associated autoinflammation with infantile enterocolitis patients, and well above levels found in most familial Mediterranean fever patients. Serum IL-18 elevation in PAPA syndrome patients persisted despite fluctuations in disease activity. Levels of the soluble IL-18 antagonist IL-18BP were modestly elevated, and PAPA syndrome patients had detectable free IL-18. PAPA syndrome was rarely associated with elevation of CXCL9, an indicator of interferon-γ activity, but no PAPA syndrome patients had a history of MAS.

CONCLUSION

PAPA syndrome is a refractory and often disabling monogenic autoinflammatory disease associated with chronic and unopposed elevation of serum IL-18 levels but not with risk of MAS. These findings affect our understanding of the diseases in which IL-18 is overproduced and suggest a link between pyrin inflammasome activation, IL-18, and autoinflammation, without susceptibility to MAS.

TNF-inhibition in vasculitis management in adenosine deaminase 2 deficiency (DADA2)

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) is a recessively inherited autoinflammatory disorder caused by a loss of functional ADA2 protein. TNF inhibition (TNFi) has proven to be highly effective in treating inflammatory manifestations.

OBJECTIVE

To explore the pathophysiology and the underlying mechanisms of TNF inhibitor response in these patients.

METHODS

We performed Sanger sequencing of the ADA2 gene. We used flow cytometry, intracellular cytokine staining, transcriptome analysis, immunohistochemistry, and cell differentiation experiments to define an inflammatory signature in DADA2 patients and studied their response to TNF inhibitor treatment.

RESULTS

We demonstrated increased inflammatory signals and overproduction of cytokines mediated by IFN and NF-κB pathways in patients' primary cells. Treatment with TNFi led to reduction in inflammation, rescued the skewed differentiation towards the pro-inflammatory M1 macrophage subset and restored integrity of endothelial cells in blood vessels. We also report 8 novel disease-associated variants in 7 patients with DADA2.

CONCLUSION

Our data explore the cellular mechanism underlying effective treatment with TNFi therapies in DADA2. DADA2 vasculitis is strongly related to the presence of activated myeloid cells and the endothelial cell damage is rescued with anti-TNF treatment.

Benign and malignant hematologic manifestations in patients with VEXAS syndrome due to somatic mutations in UBA1

Somatic mutations in UBA1 involving hematopoietic stem and myeloid cells have been reported in patients with the newly defined VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Here, we report clinical hematologic manifestations and unique bone marrow (BM) features in 16 patients with VEXAS. All patients were male and had a history of severe autoinflammatory and rheumatologic manifestations and a somatic UBA1 mutation (p.Met41). Ten patients had hematologic disorders: myelodysplastic syndrome (MDS; 6 of 16), multiple myeloma (2 of 16), monoclonal gammopathy of undetermined significance (2 of 16), and monoclonal B-cell lymphocytosis (2 of 16), and a few of those patients had 2 co-existing clonal processes. Although macrocytic anemia (100%) and lymphopenia (80%) were prevalent in all patients with VEXAS, thrombocytopenia and neutropenia were more common in patients with progression to MDS. All BMs in VEXAS patients had prominent cytoplasmic vacuoles in myeloid and erythroid precursors. In addition, most BMs were hypercellular with myeloid hyperplasia, erythroid hypoplasia, and varying degrees of dysplasia. All patients diagnosed with MDS were lower risk (low blast count, very good to intermediate cytogenetics) according to standard prognostic scoring with no known progression to leukemia. In addition, 10 of 16 patients had thrombotic events, including venous thromboembolism and arterial stroke. Although VEXAS presents symptomatically as a rheumatologic disease, morbidity and mortality are associated with progression to hematologic disease. Given the increased risk of developing MDS and multiple myeloma, surveillance for disease progression is important.

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.

Homozygous variant p. Arg90His in NCF1 is associated with early-onset Interferonopathy: a case report

BACKGROUND

Biallelic loss-of-function variants in NCF1 lead to reactive oxygen species deficiency and chronic granulomatous disease (CGD). Heterozygosity for the p.Arg90His variant in NCF1 has been associated with susceptibility to systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome in adult patients. This study demonstrates the association of the homozygous p.Arg90His variant with interferonopathy with features of autoinflammation and autoimmunity in a pediatric patient.

CASE PRESENTATION

A 5-year old female of Indian ancestry with early-onset recurrent fever and headache, and persistently elevated antinuclear, anti-Ro, and anti-La antibodies was found to carry the homozygous p.Arg90His variant in NCF1 through exome sequencing. Her unaffected parents and three other siblings were carriers for the mutant allele. Because the presence of two NCF1 pseudogenes, this variant was confirmed by independent genotyping methods. Her intracellular neutrophil oxidative burst and NCF1 expression levels were normal, and no clinical features of CGD were apparent. Gene expression analysis in peripheral blood detected an interferon gene expression signature, which was further supported by cytokine analyses of supernatants of cultured patient's cells. These findings suggested that her inflammatory disease is at least in part mediated by type I interferons. While her fever episodes responded well to systemic steroids, treatment with the JAK inhibitor tofacitinib resulted in decreased serum ferritin levels and reduced frequency of fevers.

CONCLUSION

Homozygosity for p.Arg90His in NCF1 should be considered contributory in young patients with an atypical systemic inflammatory antecedent phenotype that may evolve into autoimmunity later in life. The complex genomic organization of NCF1 poses a difficulty for high-throughput genotyping techniques and variants in this gene should be carefully evaluated when using the next generation and Sanger sequencing technologies. The p.Arg90His variant is found at a variable allele frequency in different populations, and is higher in people of South East Asian ancestry. In complex genetic diseases such as SLE, other rare and common susceptibility alleles might be necessary for the full disease expressivity.

Somatic Mutations in UBA1 Define a Distinct Subset of Relapsing Polychondritis Patients With VEXAS

OBJECTIVE

Somatic mutations in UBA1 cause a newly defined syndrome known as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome). More than 50% of patients currently identified as having VEXAS met diagnostic criteria for relapsing polychondritis (RP), but clinical features that characterize VEXAS within a cohort of patients with RP have not been defined. We undertook this study to define the prevalence of somatic mutations in UBA1 in patients with RP and to create an algorithm to identify patients with genetically confirmed VEXAS among those with RP.

METHODS

Exome and targeted sequencing of UBA1 was performed in a prospective observational cohort of patients with RP. Clinical and immunologic characteristics of patients with RP were compared based on the presence or absence of UBA1 mutations. The random forest method was used to derive a clinical algorithm to identify patients with UBA1 mutations.

RESULTS

Seven of 92 patients with RP (7.6%) had UBA1 mutations (referred to here as VEXAS-RP). Patients with VEXAS-RP were all male, were on average ≥45 years of age at disease onset, and commonly had fever, ear chondritis, skin involvement, deep vein thrombosis, and pulmonary infiltrates. No patient with VEXAS-RP had chondritis of the airways or costochondritis. Mortality was greater in VEXAS-RP than in RP (23% versus 4%; P = 0.029). Elevated acute-phase reactants and hematologic abnormalities (e.g., macrocytic anemia, thrombocytopenia, lymphopenia, multiple myeloma, myelodysplastic syndrome) were prevalent in VEXAS-RP. A decision tree algorithm based on male sex, a mean corpuscular volume >100 fl, and a platelet count <200 ×10³ /μl differentiated VEXAS-RP from RP with 100% sensitivity and 96% specificity.

CONCLUSION

Mutations in UBA1 were causal for disease in a subset of patients with RP. This subset of patients was defined by disease onset in the fifth decade of life or later, male sex, ear/nose chondritis, and hematologic abnormalities. Early identification is important in VEXAS given the associated high mortality rate.

Sequence-Based Screening of Patients With Idiopathic Polyarteritis Nodosa, Granulomatosis With Polyangiitis, and Microscopic Polyangiitis for Deleterious Genetic Variants in ADA2

OBJECTIVE

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic form of vasculitis that can resemble polyarteritis nodosa (PAN). This study was undertaken to identify potential disease-causing sequence variants in ADA2 in patients with idiopathic PAN, granulomatosis with polyangiitis (GPA), or microscopic polyangiitis (MPA).

METHODS

Patients with idiopathic PAN (n = 118) and patients with GPA or MPA (n = 1,107) were screened for rare nonsynonymous variants in ADA2 using DNA sequencing methods. ADA-2 enzyme activity was assessed in selected serum samples.

RESULTS

Nine of 118 patients with PAN (7.6%) were identified as having rare nonsynonymous variants in ADA2. Four patients (3.4%) were biallelic for pathogenic or likely pathogenic variants, and 5 patients (4.2%) were monoallelic carriers for 3 variants of uncertain significance and 2 likely pathogenic variants. Serum samples from 2 patients with PAN with biallelic variants were available and showed markedly reduced ADA-2 enzyme activity. ADA-2 enzyme testing of 86 additional patients revealed 1 individual with strongly reduced ADA-2 activity without detectable pathogenic variants. Patients with PAN and biallelic variants in ADA2 were younger at diagnosis than patients with 1 or no variant in ADA2, with no other clinical differences noted. None of the patients with GPA or MPA carried biallelic variants in ADA2.

CONCLUSION

A subset of patients with idiopathic PAN meet genetic criteria for DADA2. Given that tumor necrosis factor inhibition is efficacious in DADA2 but is not conventional therapy for PAN, these findings suggest that ADA-2 testing should strongly be considered in patients with hepatitis B virus-negative idiopathic PAN.

Systematic evaluation of nine monogenic autoinflammatory diseases reveals common and disease-specific correlations with allergy-associated features

BACKGROUND

Monogenic autoinflammatory diseases (AID) are caused by mutations in innate immune genes. The effects of these mutations on allergic inflammation are unknown.

OBJECTIVES

We investigated allergic, immunological and clinical phenotypes in FMF (familial Mediterranean fever), CAPS (cryopyrin-associated periodic syndrome), TRAPS (tumour necrosis factor receptor-associated periodic syndrome), HIDS (hyper-IgD syndrome), PAPA (pyogenic arthritis, pyoderma gangrenosum and acne), DADA2 (deficiency of adenosine deaminase 2), HA20 (haploinsufficiency of A20), CANDLE (chronic atypical neutrophilic dermatosis, lipodystrophy, elevated temperature) and SAVI (STING-associated vasculopathy of infancy).

METHODS

In this cross-sectional study, clinical data were assessed in 425 patients with AID using questionnaires and chart reviews. Comparator data were obtained from public databases. Peripheral blood mononuclear cells obtained from 55 patients were stimulated and CD4⁺ cytokine production assessed.

RESULTS

Clinical laboratory features of Type 2 immunity were elevated in CAPS but reduced in most AID, particularly DADA2. Physician-diagnosed allergic diseases were prevalent in multiple AID, including CAPS and DADA2. T helper 2 (Th2) cells were expanded in CAPS, TRAPS and HIDS; Th9 cells were expanded in HA20.

CONCLUSIONS

CAPS is characterised by an enhanced Type 2 signature, whereas FMF and CANDLE are associated with reduced Type 2 responses. DADA2 is associated with reduced Type 2 responses but a high rate of physician-diagnosed allergy. Therefore, NLRP3-driven autoinflammation may promote Type 2 immunity, whereas AID like DADA2 may manifest clinical phenotypes that masquerade as allergic disorders. Further investigations are needed to determine the contribution of autoinflammation to allergic clinical and immunological phenotypes, to improve the treatment of patients with AID.

Linkage-specific deubiquitylation by OTUD5 defines an embryonic pathway intolerant to genomic variation

Reversible modification of proteins with linkage-specific ubiquitin chains is critical for intracellular signaling. Information on physiological roles and underlying mechanisms of particular ubiquitin linkages during human development are limited. Here, relying on genomic constraint scores, we identify 10 patients with multiple congenital anomalies caused by hemizygous variants in OTUD5, encoding a K48/K63 linkage-specific deubiquitylase. By studying these mutations, we find that OTUD5 controls neuroectodermal differentiation through cleaving K48-linked ubiquitin chains to counteract degradation of select chromatin regulators (e.g., ARID1A/B, histone deacetylase 2, and HCF1), mutations of which underlie diseases that exhibit phenotypic overlap with OTUD5 patients. Loss of OTUD5 during differentiation leads to less accessible chromatin at neuroectodermal enhancers and aberrant gene expression. Our study describes a previously unidentified disorder we name LINKED (LINKage-specific deubiquitylation deficiency-induced Embryonic Defects) syndrome and reveals linkage-specific ubiquitin cleavage from chromatin remodelers as an essential signaling mode that coordinates chromatin remodeling during embryogenesis.

Somatic Mutations in UBA1 and Severe Adult-Onset Autoinflammatory Disease

BACKGROUND

Adult-onset inflammatory syndromes often manifest with overlapping clinical features. Variants in ubiquitin-related genes, previously implicated in autoinflammatory disease, may define new disorders.

METHODS

We analyzed peripheral-blood exome sequence data independent of clinical phenotype and inheritance pattern to identify deleterious mutations in ubiquitin-related genes. Sanger sequencing, immunoblotting, immunohistochemical testing, flow cytometry, and transcriptome and cytokine profiling were performed. CRISPR-Cas9-edited zebrafish were used as an in vivo model to assess gene function.

RESULTS

We identified 25 men with somatic mutations affecting methionine-41 (p.Met41) in UBA1, the major E1 enzyme that initiates ubiquitylation. (The gene UBA1 lies on the X chromosome.) In such patients, an often fatal, treatment-refractory inflammatory syndrome develops in late adulthood, with fevers, cytopenias, characteristic vacuoles in myeloid and erythroid precursor cells, dysplastic bone marrow, neutrophilic cutaneous and pulmonary inflammation, chondritis, and vasculitis. Most of these 25 patients met clinical criteria for an inflammatory syndrome (relapsing polychondritis, Sweet's syndrome, polyarteritis nodosa, or giant-cell arteritis) or a hematologic condition (myelodysplastic syndrome or multiple myeloma) or both. Mutations were found in more than half the hematopoietic stem cells, including peripheral-blood myeloid cells but not lymphocytes or fibroblasts. Mutations affecting p.Met41 resulted in loss of the canonical cytoplasmic isoform of UBA1 and in expression of a novel, catalytically impaired isoform initiated at p.Met67. Mutant peripheral-blood cells showed decreased ubiquitylation and activated innate immune pathways. Knockout of the cytoplasmic UBA1 isoform homologue in zebrafish caused systemic inflammation.

CONCLUSIONS

Using a genotype-driven approach, we identified a disorder that connects seemingly unrelated adult-onset inflammatory syndromes. We named this disorder the VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. (Funded by the NIH Intramural Research Programs and the EU Horizon 2020 Research and Innovation Program.).

Critical Signaling Events in the Mechanoactivation of Human Mast Cells through p.C492Y-ADGRE2

A role for the adhesion G-protein coupled receptor ADGRE2 or EMR2 in mechanosensing was revealed by the finding of a missense substitution (p.C492Y) associated with familial vibratory urticaria. In these patients, friction of the skin induces mast cell hyper-degranulation through p.C492Y-ADGRE2, causing localized hives, flushing, and hypotension. We have now characterized the responses and intracellular signals elicited by mechanical activation in human mast cells expressing p.C492Y-ADGRE2 and attached to dermatan sulfate, a ligand for ADGRE2. The presence of p.C492Y-ADGRE2 reduced the threshold to activation and increased the extent of degranulation along with the percentage of mast cells responding. Vibration caused phospholipase C activation, transient increases in cytosolic calcium, and downstream activation of phosphoinositide 3-kinase and extracellular signal-regulated kinases 1 and 2 by Gβγ, Gαq/11, and Gαi/o-independent mechanisms. Degranulation induced by vibration was dependent on phospholipase C pathways, including calcium, protein kinase C, and phosphoinositide 3-kinase but not extracellular signal-regulated kinases 1/2 pathways, along with pertussis toxin-sensitive signals. In addition, mechanoactivation of mast cells stimulated the synthesis and release of prostaglandin D2, to our knowledge a previously unreported mediator in vibratory urticaria, and extracellular signal-regulated kinases 1/2 activation was required for this response together with calcium, protein kinase C, and to some extent, phosphoinositide 3-kinase. Our studies thus identified critical molecular events initiated by mechanical forces and potential therapeutic targets for patients with vibratory urticaria.

Genetic control of CCL24, POR, and IL23R contributes to the pathogenesis of sarcoidosis

Sarcoidosis is a genetically complex systemic inflammatory disease that affects multiple organs. We present a GWAS of a Japanese cohort (700 sarcoidosis cases and 886 controls) with replication in independent samples from Japan (931 cases and 1,042 controls) and the Czech Republic (265 cases and 264 controls). We identified three loci outside the HLA complex, CCL24, STYXL1-SRRM3, and C1orf141-IL23R, which showed genome-wide significant associations (P < 5.0 × 10⁻⁸) with sarcoidosis; CCL24 and STYXL1-SRRM3 were novel. The disease-risk alleles in CCL24 and IL23R were associated with reduced CCL24 and IL23R expression, respectively. The disease-risk allele in STYXL1-SRRM3 was associated with elevated POR expression. These results suggest that genetic control of CCL24, POR, and IL23R expression contribute to the pathogenesis of sarcoidosis. We speculate that the CCL24 risk allele might be involved in a polarized Th1 response in sarcoidosis, and that POR and IL23R risk alleles may lead to diminished host defense against sarcoidosis pathogens.

Akira Meguro et al. report a genome-wide association study for sarcoidosis—a systemic inflammatory disease—in the Japanese population. They identify 3 non-HLA loci with genome-wide significance, 2 of which have not been previously associated with sarcoidosis in any population.

Deficiency of Adenosine Deaminase 2 (DADA2): Hidden Variants, Reduced Penetrance, and Unusual Inheritance

PURPOSE

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disorder that manifests with fever, early-onset vasculitis, strokes, and hematologic dysfunction. This study aimed to identify disease-causing variants by conventional Sanger and whole exome sequencing in two families suspected to have DADA2 and non-confirmatory genotypes. ADA2 enzymatic assay confirmed the clinical diagnosis of DADA2. Molecular diagnosis was important to accurately identify other family members at risk.

METHODS

We used a variety of sequencing technologies, ADA2 enzymatic testing, and molecular methods including qRT-PCR and MLPA.

RESULTS

Exome sequencing identified heterozygosity for the known pathogenic variant ADA2: c.1358A>G, p.Tyr453Cys in a 14-year-old female with a history of ischemic strokes, livedo, and vasculitis. No second pathogenic variant could be identified. ADA2 enzymatic testing in combination with quantitative RT-PCR suggested a loss-of-function allele. Subsequent genome sequencing identified a canonical splice site variant, c.-47+2T>C, within the 5'UTR of ADA2. Two of her unaffected siblings were found to carry the same two pathogenic variants. A homozygous 800-bp duplication comprising exon 7 of ADA2 was identified in a 5-year-old female with features consistent with Diamond-Blackfan anemia (DBA). The duplication was missed by Sanger sequencing of ADA2, chromosomal microarray, and exome sequencing but was detected by MLPA in combination with long-read PCR sequencing. The exon 7 duplication was also identified in her non-symptomatic father and younger sister.

CONCLUSIONS

ADA2 pathogenic variants may not be detected by conventional sequencing and genetic testing and may require the incorporation of additional diagnostic methods. A definitive molecular diagnosis is crucial for all family members to make informed treatment decisions.

Common genetic susceptibility loci link PFAPA syndrome, Behçet's disease, and recurrent aphthous stomatitis

Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children. The disease appears to cluster in families, but the pathogenesis is unknown. We queried two European-American cohorts and one Turkish cohort (total n = 231) of individuals with PFAPA for common variants previously associated with two other oropharyngeal ulcerative disorders, Behçet's disease and recurrent aphthous stomatitis. In a metaanalysis, we found that a variant upstream of IL12A (rs17753641) is strongly associated with PFAPA (OR 2.13, P = 6 × 10-9). We demonstrated that monocytes from individuals who are heterozygous or homozygous for this risk allele produce significantly higher levels of IL-12p70 upon IFN-γ and LPS stimulation than those from individuals without the risk allele. We also found that variants near STAT4, IL10, and CCR1-CCR3 were significant susceptibility loci for PFAPA, suggesting that the pathogenesis of PFAPA involves abnormal antigen-presenting cell function and T cell activity and polarization, thereby implicating both innate and adaptive immune responses at the oropharyngeal mucosa. Our results illustrate genetic similarities among recurrent aphthous stomatitis, PFAPA, and Behçet's disease, placing these disorders on a common spectrum, with recurrent aphthous stomatitis on the mild end, Behçet's disease on the severe end, and PFAPA intermediate. We propose naming these disorders Behçet's spectrum disorders to highlight their relationship. HLA alleles may be factors that influence phenotypes along this spectrum as we found new class I and II HLA associations for PFAPA distinct from Behçet's disease and recurrent aphthous stomatitis.

Mutations that prevent caspase cleavage of RIPK1 cause autoinflammatory disease

Receptor Interacting Protein Kinase 1 (RIPK1) is a key regulator of innate immune signalling pathways. To ensure an optimal inflammatory response, RIPK1 is post-translationally regulated by well characterised ubiquitylation and phosphorylation events, as well as caspase-8 mediated cleavage^1–7. The physiological relevance of this cleavage remains unclear, though it is believed to inhibit activation of RIPK3 and necroptosis⁸. Here we show that heterozygous missense mutations p.D324N, p.D324H and p.D324Y prevent caspase cleavage of RIPK1 in humans and result in early-onset periodic fever episodes and severe intermittent lymphadenopathy, a condition we designate ‘Cleavage-resistant RIPK1-Induced Autoinflammatory’ (CRIA) syndrome. To define the mechanism for this disease we generated a cleavage-resistant Ripk1^D325A mutant mouse strain. While Ripk1^-/- mice die postnatally from systemic inflammation, Ripk1^D325A/D325A mice died during embryogenesis. Embryonic lethality was completely prevented by combined loss of Casp8 and Ripk3 but not by loss of Ripk3 or Mlkl alone. Loss of RIPK1 kinase activity also prevented Ripk1^D325A/D325A embryonic lethality, however the mice died before weaning from multi organ inflammation in a RIPK3 dependent manner. Consistently, Ripk1^D325A/D325A and Ripk1^D325A/+ cells were hypersensitive to RIPK3 dependent TNF-induced apoptosis and necroptosis. Heterozygous Ripk1^D325A/+ mice were viable and grossly normal, but were hyper-responsive to inflammatory stimuli in vivo. Our results demonstrate the importance of caspase-mediated RIPK1 cleavage during embryonic development and show that caspase cleavage of RIPK1 not only inhibits necroptosis but maintains inflammatory homeostasis throughout life.

The Pyrin Inflammasome in Health and Disease

The pyrin inflammasome has evolved as an innate immune sensor to detect bacterial toxin-induced Rho guanosine triphosphatase (Rho GTPase)-inactivation, a process that is similar to the “guard” mechanism in plants. Rho GTPases act as molecular switches to regulate a variety of signal transduction pathways including cytoskeletal organization. Pathogens can modulate Rho GTPase activity to suppress host immune responses such as phagocytosis. Pyrin is encoded by MEFV, the gene that is mutated in patients with familial Mediterranean fever (FMF). FMF is the prototypic autoinflammatory disease characterized by recurring short episodes of systemic inflammation and is a common disorder in many populations in the Mediterranean basin. Pyrin specifically senses modifications in the activity of the small GTPase RhoA, which binds to many effector proteins including the serine/threonine-protein kinases PKN1 and PKN2 and actin-binding proteins. RhoA activation leads to PKN-mediated phosphorylation-dependent pyrin inhibition. Conversely, pathogen virulence factors downregulate RhoA activity in a variety of ways, and these changes are detected by the pyrin inflammasome irrespective of the type of modifications. MEFV pathogenic variants favor the active state of pyrin and elicit proinflammatory cytokine release and pyroptosis. They can be inherited either as a dominant or recessive trait depending on the variant's location and effect on the protein function. Mutations in the C-terminal B30.2 domain are usually considered recessive, although heterozygotes may manifest a biochemical or even a clinical phenotype. These variants are hypomorphic in regard to their effect on intramolecular interactions, but ultimately accentuate pyrin activity. Heterozygous mutations in other domains of pyrin affect residues critical for inhibition or protein oligomerization, and lead to constitutively active inflammasome. In healthy carriers of FMF mutations who have the subclinical inflammatory phenotype, the increased activity of pyrin might have been protective against endemic infections over human history. This finding is supported by the observation of high carrier frequencies of FMF-mutations in multiple populations. The pyrin inflammasome also plays a role in mediating inflammation in other autoinflammatory diseases linked to dysregulation in the actin polymerization pathway. Therefore, the assembly of the pyrin inflammasome is initiated in response to fluctuations in cytoplasmic homeostasis and perturbations in cytoskeletal dynamics.

Deficiency of adenosine deaminase 2 triggers adenosine-mediated NETosis and TNF production in patients with DADA2

Reduction of adenosine deaminase 2 (ADA2) activity due to autosomal-recessive loss-of-function mutations in the ADA2 gene (previously known as CECR1) results in a systemic vasculitis known as deficiency of ADA2 (DADA2). Neutrophils and a subset of neutrophils known as low-density granulocytes (LDGs) have been implicated in the pathogenesis of vasculitis, at least in part, through the formation of neutrophil extracellular traps (NETs). The study objective was to determine whether neutrophils and NETs play a pathogenic role in DADA2. In vivo evidence demonstrated NETs and macrophages in affected gastrointestinal tissue from patients with DADA2. An abundance of circulating LDGs prone to spontaneous NET formation was observed during active disease in DADA2 and were significantly reduced after remission induction by anti-tumor necrosis factor (TNF) therapy. Increased circulating LDGs were identified in unaffected family members with monoallelic ADA2 mutations. Adenosine triggered NET formation, particularly in neutrophils from female patients, by engaging A1 and A3 adenosine receptors (ARs) and through reactive oxygen species- and peptidylarginine deiminase-dependent pathways. Adenosine-induced NET formation was inhibited by recombinant ADA2, A1/A3 AR antagonists, or by an A2A agonist. M1 macrophages incubated with NETs derived from patients with DADA2 released significantly greater amounts of TNF-α. Treatment with an A2AAR agonist decreased nuclear translocation of NF-κB and subsequent production of inflammatory cytokines in DADA2 monocyte-derived macrophages. These results suggest that neutrophils may play a pathogenic role in DADA2. Modulation of adenosine-mediated NET formation may contribute a novel and directed therapeutic approach in the treatment of DADA2 and potentially other inflammatory diseases.

Second Case of HOIP Deficiency Expands Clinical Features and Defines Inflammatory Transcriptome Regulated by LUBAC

Background: HOIP is the catalytic subunit of the linear ubiquitination chain assembly complex (LUBAC) that is essential for NF-κB signaling and thus proper innate and adaptive immunity. To date only one patient with HOIP deficiency has been reported with clinical characteristics that include autoinflammation, immunodeficiency, amylopectinosis, and systemic lymphangiectasia.

Case: We sought to identify a genetic cause of a disease for an 8 year-old girl who presented with early-onset immune deficiency and autoinflammation.

Methods: Targeted next generation sequencing of 352 immune-related genes was performed. Functional studies included transcriptome analysis, cytokine profiling, and protein analysis in patients' primary cells.

Results: We identified biallelic variants in close proximity to splice sites (c.1197G>C and c.1737+3A>G) in the RNF31 gene. RNA extracted from patient cells showed alternatively spliced transcripts not present in control cells. Protein expression of HOIP and LUBAC was reduced in primary cells as shown by western blotting. Patient-derived fibroblasts demonstrated attenuated IL-6 production, while PBMCs showed higher TNF production after stimulation with proinflammatory cytokines. RNA sequencing of whole blood RNA and PBMCs demonstrated a marked transcriptome wide change including differential expression of type I interferon regulated genes.

Conclusion: We report the second case of HOIP deficiency with novel compound heterozygous mutations in RNF31 and distinct clinical and molecular features. Our results expand on the clinical spectrum of HOIP deficiency and molecular signatures associated with LUBAC deficiency.

Brief Report: Whole-Exome Sequencing to Identify Rare Variants and Gene Networks That Increase Susceptibility to Scleroderma in African Americans

OBJECTIVE

Whole-exome sequencing (WES) studies in systemic sclerosis (SSc) patients of European American (EA) ancestry have identified variants in the ATP8B4 gene and enrichment of variants in genes in the extracellular matrix (ECM)-related pathway that increase SSc susceptibility. This study was undertaken to evaluate the association of the ATP8B4 gene and the ECM-related pathway with SSc in a cohort of African American (AA) patients.

METHODS

SSc patients of AA ancestry were enrolled from 23 academic centers across the US under the Genome Research in African American Scleroderma Patients consortium. Unrelated AA individuals without serologic evidence of autoimmunity who were enrolled in the Howard University Family Study were used as unaffected controls. Functional variants in genes reported in the 2 WES studies in EA patients with SSc were selected for gene association testing using the optimized sequence kernel association test (SKAT-O) and pathway analysis by Ingenuity Pathway Analysis in 379 patients and 411 controls.

RESULTS

Principal components analysis demonstrated that the patients and controls had similar ancestral backgrounds, with roughly equal proportions of mean European admixture. Using SKAT-O, we examined the association of individual genes that were previously reported in EA patients and none remained significant, including ATP8B4 (P = 0.98). However, we confirmed the previously reported association of the ECM-related pathway with enrichment of variants within the COL13A1, COL18A1, COL22A1, COL4A3, COL4A4, COL5A2, PROK1, and SERPINE1 genes (corrected P = 1.95 × 10^-4 ).

CONCLUSION

In the largest genetic study in AA patients with SSc to date, our findings corroborate the role of functional variants that aggregate in a fibrotic pathway and increase SSc susceptibility.