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.

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.

Spatial Morphoproteomic Features Predict Uniqueness of Immune Microarchitectures and Responses in Lymphoid Follicles.

Multiplex imaging technologies allow the characterization of single cells in their cellular environments. Understanding the organization of single cells within their microenvironment and quantifying disease-status related biomarkers is essential for multiplex datasets. Here we proposed SNOWFLAKE, a graph neural network framework pipeline for the prediction of disease-status from combined multiplex cell expression and morphology in human B-cell follicles. We applied SNOWFLAKE to a multiplex dataset related to COVID-19 infection in humans and showed better predictive power of the SNOWFLAKE pipeline compared to other machine learning and deep learning methods. Moreover, we combined morphological features inside graph edge features to utilize attribution methods for extracting disease-relevant motifs from single-cell spatial graphs. The underlying subgraphs were further analyzed and associated with disease status across the dataset. We showed that SNOWFLAKE successfully extracted significant low dimensional embedding from subgraphs with a clear separation between disease status and helped characterize unique cellular interactions in the subgraphs. SNOWFLAKE is a generalizable pipeline for the analysis of multiplex imaging data modality by extracting disease-relevant subgraphs guided by graph-level prediction.

What is PFAPA syndrome? Genetic clues about the pathogenesis.

PURPOSE OF REVIEW: Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in childhood. Recent studies report genetic susceptibility variants for PFAPA syndrome and the efficacy of tonsillectomy in a broader cohort of patients with recurrent stereotypical fever. In this review, we highlight the findings of these studies and what they may reveal about the pathogenesis of PFAPA. RECENT FINDINGS: Newly identified genetic susceptibility loci for PFAPA suggest that it is a complex genetic disorder linked to Behçet's disease and recurrent aphthous ulcers. Patients who have PFAPA with some features of Behçet's disease have been reported. Moreover, the efficacy of tonsillectomy has now been described in patients who do not meet the full diagnostic criteria for PFAPA, although the immunologic profile in the tonsils is different from those with PFAPA. Factors that predict response to tonsillectomy are also reported. SUMMARY: These findings highlight the heterogeneous phenotypes that may be related to PFAPA due to common genetic susceptibility or response to therapy. These relationships raise questions about how to define PFAPA and highlight the importance of understanding of the genetic architecture of PFAPA and related diseases.

Dynamic chromatin accessibility licenses STAT5- and STAT6-dependent innate-like function of TH9 cells to promote allergic inflammation.

Allergic diseases are a major global health issue. Interleukin (IL)-9-producing helper T (TH9) cells promote allergic inflammation, yet TH9 cell effector functions are incompletely understood because their lineage instability makes them challenging to study. Here we found that resting TH9 cells produced IL-9 independently of T cell receptor (TCR) restimulation, due to STAT5- and STAT6-dependent bystander activation. This mechanism was seen in circulating cells from allergic patients and was restricted to recently activated cells. STAT5-dependent Il9/IL9 regulatory elements underwent remodeling over time, inactivating the locus. A broader 'allergic TH9' transcriptomic and epigenomic program was also unstable. In vivo, TH9 cells induced airway inflammation via TCR-independent, STAT-dependent mechanisms. In allergic patients, TH9 cell expansion was associated with responsiveness to JAK inhibitors. These findings suggest that TH9 cell instability is a negative checkpoint on bystander activation that breaks down in allergy and that JAK inhibitors should be considered for allergic patients with TH9 cell expansion.

Protein phosphatase 2A propels follicular T helper cell development in lupus.

Follicular helper T (Tfh) cells are important for generating humoral immune responses by helping B cells form germinal centers (GCs) and the production of high-affinity antibodies. However, aberrant Tfh cell expansion also contributes to the generation of self-reactive autoantibodies and promotes autoantibody-mediated autoimmune diseases such as systemic lupus erythematosus (SLE). Protein phosphatase 2A catalytic subunit alpha isoform (PP2A Cα) expression levels are elevated in peripheral T cells of SLE patients and positively correlate with autoantibody titers and disease activity. Here, we demonstrate a critical role of PP2A in Tfh differentiation by using T cell restricted PP2A Cα deficient mice. We observed impaired Tfh differentiation and GC response in two different classical Tfh induction models. Mechanistic studies revealed that downregulation of protein translation of the Tfh lineage transcription factor BCL6 in PP2A deficient T cells. Importantly, we found that PP2A deficiency by either gene knockout or chemical inhibition alleviated lupus severity in mice. Lastly, we confirmed a positive correlation between PP2A Cα and BCL6 protein levels in human CD4+ T cells from patients with SLE. In summary, our study revealed a critical role of PP2A in regulating Tfh cells and suggests it is a potential therapeutic target for lupus.

Adaptive immune responses to SARS-CoV-2 persist in the pharyngeal lymphoid tissue of children.

Most studies of adaptive immunity to SARS-CoV-2 infection focus on peripheral blood, which may not fully reflect immune responses at the site of infection. Using samples from 110 children undergoing tonsillectomy and adenoidectomy during the COVID-19 pandemic, we identified 24 samples with evidence of previous SARS-CoV-2 infection, including neutralizing antibodies in serum and SARS-CoV-2-specific germinal center and memory B cells in the tonsils and adenoids. Single-cell B cell receptor (BCR) sequencing indicated virus-specific BCRs were class-switched and somatically hypermutated, with overlapping clones in the two tissues. Expanded T cell clonotypes were found in tonsils, adenoids and blood post-COVID-19, some with CDR3 sequences identical to previously reported SARS-CoV-2-reactive T cell receptors (TCRs). Pharyngeal tissues from COVID-19-convalescent children showed persistent expansion of germinal center and antiviral lymphocyte populations associated with interferon (IFN)-γ-type responses, particularly in the adenoids, and viral RNA in both tissues. Our results provide evidence for persistent tissue-specific immunity to SARS-CoV-2 in the upper respiratory tract of children after infection.

Examining multi-level immune response to determine prevalence of COVID-19 in pediatric tonsillectomy.

OBJECTIVE: To determine the prevalence of COVID-19 in a cohort of children undergoing tonsillectomy through assessment of B cell immune responses to SARS-CoV-2 in both peripheral blood and tonsil tissue. METHODS: In this cohort study at a tertiary pediatric hospital (Children's National Hospital) in Washington, DC, we recruited 100 children undergoing tonsillectomy from late September 2020 to January 2021. Serum, peripheral blood cells, and tonsil tissue were collected and examined for immune reactivity to SARS-CoV-2. Parent-reported clinical histories were compared to antibody and B-cell responses. RESULTS: Among 100 children undergoing tonsillectomy, 19% had evidence of immune responses to SARS-CoV-2 (CoV2+), indicating prior COVID-19. In all seropositive participants, we detected SARS-CoV-2 specific B cells in both peripheral blood mononuclear cells and tonsils, providing evidence for tissue-specific immunity in these children. Of the 19, 63% reported no known history of COVID-19, and an additional 3 were asymptomatic or unaware of an acute infection when detected on pre-surgery screen. Hispanic children represented 74% of CoV2+ subjects compared to 37% of the full cohort. 100% of CoV2+ children lived in a zip code with poverty level >10%. CONCLUSIONS: Nearly one-fifth of children undergoing tonsillectomy at an urban U.S. hospital had evidence of prior COVID-19 during the early pandemic, with the majority unaware of prior infection. Our results underscore the ethnic and socio-economic disparities of COVID-19. We found concordant evidence of humoral immune responses in children in both blood and tonsil tissue, providing evidence of local immune responses in the upper respiratory tract. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:1993-1999, 2023.

Robust, persistent adaptive immune responses to SARS-CoV-2 in the oropharyngeal lymphoid tissue of children.

SARS-CoV-2 infection triggers adaptive immune responses from both T and B cells. However, most studies focus on peripheral blood, which may not fully reflect immune responses in lymphoid tissues at the site of infection. To evaluate both local and systemic adaptive immune responses to SARS-CoV-2, we collected peripheral blood, tonsils, and adenoids from 110 children undergoing tonsillectomy/adenoidectomy during the COVID-19 pandemic and found 24 with evidence of prior SARS-CoV-2 infection, including detectable neutralizing antibodies against multiple viral variants. We identified SARS-CoV-2-specific germinal center (GC) and memory B cells; single cell BCR sequencing showed that these virus-specific B cells were class-switched and somatically hypermutated, with overlapping clones in the adenoids and tonsils. Oropharyngeal tissues from COVID-19-convalescent children showed persistent expansion of GC and anti-viral lymphocyte populations associated with an IFN-γ-type response, with particularly prominent changes in the adenoids, as well as evidence of persistent viral RNA in both tonsil and adenoid tissues of many participants. Our results show robust, tissue-specific adaptive immune responses to SARS-CoV-2 in the upper respiratory tract of children weeks to months after acute infection, providing evidence of persistent localized immunity to this respiratory virus.

Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome: A review.

Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome is the most common periodic fever condition in children, with most cases appearing by the age of 5. Although PFAPA is generally a self-limited condition, it can have a major impact on a child's quality of life, as well as that of their family. Recent research has continued to shed light on the genetic and immunologic factors that play a role in the pathogenesis of PFAPA. There also exists significant heterogeneity in treatment strategies, and progress has been made to develop evidence-based management strategies and establish a standard of care. This review will outline current knowledge regarding the pathogenesis of PFAPA, as well as treatment strategies and our clinical experience.

Reflections on the Mentor-Mentee Relationship.

A successful mentoring relationship can bring significant benefits to the mentee in terms of academic research productivity and career satisfaction. Through their mentees, mentors can also traverse new and fulfilling research directions. Here, we reflect on our own mentor-mentee relationship from both of our vantage points. We offer advice on how to choose a mentee/mentor, what each person needs to bring to the relationship, and how the relationship changes with time. Summary: We reflect on how mentors and mentees can make their relationship fulfilling and successful for both.

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.).

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.

Consensus treatment plans for periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome (PFAPA): a framework to evaluate treatment responses from the childhood arthritis and rheumatology research alliance (CARRA) PFAPA work group.

BACKGROUND: Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children. There is considerable heterogeneity in management strategies and a lack of evidence-based treatment guidelines. Consensus treatment plans (CTPs) are standardized treatment regimens that are derived based upon best available evidence and current treatment practices that are a way to enable comparative effectiveness studies to identify optimal therapy and are less costly to execute than randomized, double blind placebo controlled trials. The purpose of this project was to develop CTPs and response criteria for PFAPA. METHODS: The CARRA PFAPA Working Group is composed of pediatric rheumatologists, infectious disease specialists, allergists/immunologists and otolaryngologists. An extensive literature review was conducted followed by a survey to assess physician practice patterns. This was followed by virtual and in-person meetings between 2014 and 2018. Nominal group technique (NGT) was employed to develop CTPs, as well as inclusion criteria for entry into future treatment studies, and response criteria. Consensus required 80% agreement. RESULTS: The PFAPA working group developed CTPs resulting in 4 different treatment arms: 1. Antipyretic, 2. Abortive (corticosteroids), 3. Prophylaxis (colchicine or cimetidine) and 4. Surgical (tonsillectomy). Consensus was obtained among CARRA members for those defining patient characteristics who qualify for participation in the CTP PFAPA study. CONCLUSION: The goal is for the CTPs developed by our group to lead to future comparative effectiveness studies that will generate evidence-driven therapeutic guidelines for this periodic inflammatory disease.

Unique histologic features of tonsils from patients with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome.

The objective of this study is to compare the histology and immune cell composition of tonsils from patients with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome to those from patients with obstructive sleep apnea (OSA). Patients with PFAPA and age-matched controls with OSA who had undergone tonsillectomy at Vanderbilt Children's Hospital were recruited. After informed consent, archival paraffin-embedded, formalin-fixed tonsil tissues were obtained. Sizes of major histologic regions were measured. Cores of germinal centers, crypts, and squamous epithelium were assembled on a tissue microarray for immunohistochemical staining and digital image analysis. Features of tonsils from PFAPA and OSA patients were compared with Wilcoxon signed-rank test. Samples from 16 cases with PFAPA and 16 controls with OSA were evaluated. Tonsils from PFAPA cases had significantly smaller germinal centers (0.18 vs. 0.47 mm2, p = 0.001) and wider squamous epithelia (176 vs. 138 µm, p = 0.008) than those of OSA patients. The percentages of B and T lymphocytes and myeloid cells were comparable in germinal centers, crypts, and squamous epithelia from PFAPA and OSA patients. Longer time from the last febrile episode in PFAPA cases was associated with larger germinal center area (Spearman's rho = 0.61, p = 0.02). We found differences in the sizes of germinal centers and squamous epithelia in tonsils of patients with PFAPA and OSA, but the cellular compositions within these areas were comparable. Our results suggest that tonsils from patients with PFAPA change histologically over time with enlarging germinal centers following a febrile episode. Additional studies are needed to understand the pathogenesis of PFAPA.

Corrigendum: The monogenic autoinflammatory diseases define new pathways in human innate immunity and inflammation.

This corrects the article DOI: 10.1038/ni.3777.

The monogenic autoinflammatory diseases define new pathways in human innate immunity and inflammation.

Autoinflammatory diseases were first recognized nearly 20 years ago as distinct clinical and immunological entities caused by dysregulation in the innate immune system. Since then, advances in genomic techniques have led to the identification of new monogenic disorders and their corresponding signaling pathways. Here we review these monogenic autoinflammatory diseases, ranging from periodic fever syndromes caused by dysregulated inflammasome-mediated production of the cytokine IL-1ß to disorders arising from perturbations in signaling by the transcription factor NF-κB, ubiquitination, cytokine signaling, protein folding, type I interferon production and complement activation, and we further examine their molecular mechanisms. We also explore the overlap among autoinflammation, autoimmunity and immunodeficiency, and pose a series of unanswered questions that are expected to be central in autoinflammatory disease research in the coming decade.

Unraveling the pathogenesis of periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis through genetic, immunologic, and microbiologic discoveries: an update.

PURPOSE OF REVIEW: Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is considered the most common periodic fever syndrome of childhood. Although it was first described three decades ago, the pathogenesis has been poorly understood. Recent studies on the heritability and immunology of the disorder have begun to shed light into the mechanisms of this autoinflammatory disorder. This review will focus on the pathogenesis of PFAPA, especially as it pertains to the genetic susceptibility, tonsillar immunology, and the role of the microbiome. RECENT FINDINGS: Recent literature provides insights into the heritability, potential genetic modifiers, and the immunologic and microbiological profile of the tonsils in this syndrome. SUMMARY: Evidence is mounting that PFAPA is inherited as a complex genetic disease. Furthermore, tonsillectomy is curative in the majority of patients, including those who do not meet the complete clinical criteria for PFAPA. The tonsils in PFAPA patients may exhibit unique immunologic and microbiological features. The goal of this review is to outline these new developments.