Journal of Allergy and Clinical Immunology

BackgroundImmunoglobulin E (IgE) plays a fundamental role in the pathogenesis of allergic disease, including asthma. The IgE-producing plasma cells (PCs) are thought to persist indefinitely, providing a sustained source of allergen-specific IgE. Although these cells can accumulate in the bone marrow (BM), after prolonged allergen exposure, their frequency remains remarkably low, and the mechanisms that regulate their migration are poorly understood. ObjectiveTo investigate the chemokine receptor profile and the migration potential of the human IgE-producing cells. MethodsTonsil B cells were stimulated with IL-4 and anti-CD40 to induce class switching to IgE and IgG1. The chemokine receptor profile of IgE+ and IgG1+ switched cells was determined using flow cytometry and migration towards relevant chemokines was quantified using transwell chemotaxis assays. Chemokine expression was also validated by re-analysis of a published single cell RNA sequencing (scRNAseq) dataset of PCs isolated from nasal polyps (NP) of patients with allergic fungal rhinosinusitis. ResultsIgE PCs exhibit significantly reduced expression of the BM-homing chemokine receptor CXCR4 and impaired migration towards its ligand, CXCL12. While IgE+ PCs can upregulate CCR10 and respond to its ligand, CCL28, this behaviour is similar to IgG1+ PCs. Strikingly, however, IgE PCs selectively upregulate CCR2 and migrate robustly towards its ligand CCL2. Re-analysis of NP scRNAseq data confirmed that IgE PCs express significantly higher levels of CCR2 compared with PCs of all other isotypes. ConclusionsThese findings identify CCR2 as a key regulator of IgE PC migration and provide insights into their homing preferences that may shape the nature of the IgE responses.

BackgroundT helper 2 (Th2) lymphocytes orchestrate type-2 immunity and drive allergic diseases that disproportionately affect females. Sexual dimorphism in Th2 responses is well-documented, yet current models attribute sex differences exclusively to circulating gonadal hormones and sex chromosomes. Whether cell-intrinsic steroidogenesis, mediated by the enzyme Cyp11a1, contributes to female-biased Th2 differentiation and function remains unknown. MethodsTranscriptomes of in vitro generated Th2 cells from male and female T cell-specific Cyp11a1-knockout (Cyp11a1fl/fl;Cd4Cre) and control (Cyp11a1fl/fl) mice were compared. Differential expression, hallmark pathway analysis, transcription factor activity scoring, and functional assays were performed across sexes and genotypes. Cyp11a1-dependent differentially expressed genes were integrated with sex-stratified human Th2 transcriptomes obtained from the type-2 inflammatory skin disease atopic dermatitis. ResultsCyp11a1 deletion markedly reduced the transcriptional signature distinguishing female from male Th2 cells. Female Cyp11a1-knockout Th2 cells underwent extensive transcriptomic reprogramming converging toward the male profile, while male cells were largely unaffected. Female-specific pathway changes included reduced inflammatory signatures and enhanced cell-cycle programmes. Functionally, female Cyp11a1-deficient Th2 cells exhibited significantly increased proliferation and elevated IL-13 production; male knockout cells showed no comparable changes. These effects were developmentally stage-specific, emerging during Th2 differentiation but not in naive precursors. Cross-species analysis identified a conserved gene module shared between Cyp11a1-deficient female mouse Th2 cells and female-biased human Th2 cells in atopic dermatitis. ConclusionsCyp11a1-mediated steroidogenesis is a cell-intrinsic regulator of the female-biased Th2 transcriptional and functional state, identifying de novo steroidogenesis as a mechanism of immunological sexual dimorphism with direct relevance for female-predominant allergic disease.

Background: The chromosome 1q31 Th2 pathway-associated interval has been linked to asthma, but its phenotype specificity and cross-ancestry architecture remain unclear. Methods: We analyzed African (AFR) and European (EU) ancestry datasets, including 9,965 asthma cases and 37,391 controls of AFR, and 6,074 cases and 116,255 controls of EU ancestry. Imputed dosage-based association analyses were performed for asthma, steroid-dependent asthma (SDA), and non-steroid-dependent asthma, followed by QC-filtered SDA remapping, leave-one-batch-out analysis, cross-ancestry comparison, and functional enrichment. Results: Strong regional association was observed only for SDA. After quality-control (QC) filtering, the SDA signal remained significant in both ancestries, with 2,280 genome-wide significant variants in AFR and 859 in EU. Cross-ancestry comparison identified 3,129 significant variants: 10 shared, 2,270 AFR-specific, and 849 EU-specific. Shared variants showed concordant effects, whereas 237 variants showed nominal heterogeneity. AFR-specific signals included PTPRC variants with larger effects in AFR. Functional enrichment suggested different biological emphases within the same interval: immune and contractile airway-wall biology in AFR, and additional neuroaxonal components in EU. Conclusions: The 1q31 interval is strongly associated with SDA in both AFR and EU populations, and its fine-scale architecture differs by ancestry. These findings highlight population-specific effects within a shared SDA susceptibility interval, with potential implications for population-informed precision medicine in steroid responsiveness and asthma management.

Immunoglobulin E (IgE) drives allergic disease, yet what restrains the persistence of IgE production remains poorly understood. Mouse studies suggest that BCR-induced apoptosis limits the survival of IgE-producing plasma cells (PCs). Whether this mechanism applies to human IgE PCs is unclear. Using a human IgE class-switching system, we show that BCR crosslinking preferentially kills IgE PCs compared to IgG1+ PCs. However, this selective sensitivity is not explained by surface BCR levels or proximal BCR signaling as suggested in mice. Instead, elevated PTEN expression in IgE PCs constrains PI3K/Akt pro-survival signaling and lowers the apoptotic threshold by upregulating BIM, while JNK signaling sustains PTEN expression and amplifies their apoptotic sensitivity. CRISPR/Cas9 targeting of PTEN or BIM, or JNK inhibition protects IgE PCs from BCR-mediated killing. Therapeutic anti-IgE antibodies, including omalizumab and extracellular membrane-proximal domain (EMPD)-targeting antibodies, exploit this sensitivity to selectively eliminate IgE PCs and suppress IgE production, providing a mechanistic rationale for depleting IgE PCs in allergic disease. SummaryRamadani et al. identify a JNK/PTEN/BIM signaling axis that intrinsically limits human IgE plasma cell survival and drives their preferential sensitivity to BCR-induced apoptosis. This mechanism is distinct from that established in mice and has direct implications for anti-IgE therapeutic strategies.

Background: The determinants of immunoglobulin E (IgE) remain poorly understood in older adults, a population with an increasing burden of chronic diseases. Identifying IgE's determinants may improve its clinical interpretation in the evaluation of allergic and IgE-related conditions. Objective: To investigate age, sex, smoking, alcohol, body mass index (BMI), corticosteroid use, and season as potential determinants of total IgE (tIgE) and inhaled allergen-specific IgE (sIgE). Methods: Using Rotterdam Study data, we investigated the determinants of tIgE and sIgE using multivariable linear regression. Longitudinal changes and the effects of corticosteroids were assessed with linear mixed models. Results: We included 8769 participants, of which 478 had repeated IgE measurements. Age showed a U-shaped relationship with tIgE and L-shaped relationship with sIgE (both p<0.001). Women had lower tIgE (OR [95%CI]: 0.69 [0.65-0.74]), whereas current smokers (1.34 [1.23-1.46]), higher BMI (1.01 [1.01-1.02]), topical corticosteroid users (1.27 [1.07-1.50]) and inhaled corticosteroid users (1.93 [1.64-2.26]) showed higher tIgE. Women (0.96 [0.92-1.00]), former smokers (0.87 [0.83-0.91]) and current smokers (0.72 [0.68-0.76]) had lower sIgE, whereas topical corticosteroid users (1.20 [1.07-1.35]) and inhaled corticosteroid users (1.20 [1.07-1.35]) showed higher sIgE. Over time, tIgE and sIgE decreased (p<0.001) but did not significantly change after corticosteroid use. Conclusion: We identified age, sex, smoking, BMI, season and topical and inhaled corticosteroids as determinants of tIgE and sIgE. Incorporating these determinants may improve IgE's clinical interpretation for the diagnosis and management of allergic and IgE-related conditions. Future research should investigate how these determinants shape IgE's relationship with chronic diseases in aging populations.

Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) is characterized by prepubertal abrupt onset of obsessive-compulsive disorder (OCD). The sine qua non is group A streptococcus (GAS) infection, which is hypothesized to elicit an IgG-class anti-GAS antibody response that cross-reacts with antigens in the basal ganglia. However, the association between GAS antibody (GAS-IgG) levels and PANDAS has been inconsistent, and qualitative differences in GAS-IgG profiles have not been carefully evaluated in well-phenotyped cohorts. Moreover, independent studies have yet to converge on anti-neural autoantibodies that are specific to PANDAS. Here, we used phage display immunoprecipitation sequencing (PhIP-Seq) to perform ultra-deep anti-pathogen antibody repertoire profiling of serum from definitive pediatric PANDAS patients (N = 34) collected as part of a prior double-blind, placebo-controlled clinical trial of intravenous immunoglobulin (IVIg). PANDAS cases were compared to pediatric controls without a history of neuropsychiatric illness (N = 31). To assess for objective evidence of neuroglial injury, serum neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) levels were compared to healthy pediatric controls. Within PANDAS, NfL and GFAP levels were compared between pre- and post-treatment sera. To evaluate for central autoantibodies, a subset of baseline cerebrospinal fluid (CSF) samples (N = 25) was profiled by full-length human protein microarray. Though GAS reactivity by PhIP-Seq was well correlated with clinical anti-DNaseB and anti-streptolysin O titers, there were no quantitative or qualitative differences in GAS-IgG profiles between PANDAS and controls. Furthermore, NfL and GFAP levels did not differ between cases and controls. Within PANDAS, changes in NfL or GFAP levels at six weeks did not differ between placebo and IVIg groups. However, CSF autoantibody profiling by protein microarray revealed infrequent but notable candidate autoantibodies. In one patient, we identified autoantibodies against Argonaute family proteins (AGO-IgG), a marker of autoimmune sensory neuropathy. Longitudinal measurement of AGO-IgG in sera revealed that titers were unchanged after placebo, but decreased after IVIg, coinciding with symptomatic improvement, including a decrease in that patients CY-BOCS score. Overall, these results do not support an etiologic role for GAS-IgG in PANDAS. However, some individuals diagnosed with PANDAS may harbor anti-neural autoantibodies.

Immune checkpoint inhibitor-induced lichen planus (ICI-LP) is a cutaneous immune related adverse event (irAE) that shares key clinicopathologic features with spontaneous lichen planus (LP) but differs histologically and in the sex distribution of its incidence, and may therefore reflect a distinct tissue inflammatory state. To define the cellular programs that distinguish ICI-LP from LP, we profiled lesional skin by single cell and spatial transcriptomic approaches. We found few differences in the T cell and keratinocyte compartments between ICI-LP and LP, which shared similar inflammatory signatures. Rather, the dominant transcriptional features differentiating these two eruptions occurred within the fibroblast and myeloid cell compartments. Fibroblasts in ICI-LP were enriched for IGF1, FGF7, and androgen-response-associated programs, whereas myeloid cells exhibited amplified JAK-STAT and interferon-responsive states spanning both type I and type II interferon signatures. The potential role of androgen response in shaping lichenoid inflammation was supported by a striking loss of androgen receptor expression in lesional keratinocytes by immunohistochemistry. Furthermore, using spatial RNA and transcriptomic approaches, we identified anatomically segregated IFNG, IL17A, and IL13 niches within lesional skin, suggesting that regional immune compartmentalization with differences in local immunoregulation may explain the mixed inflammatory features reported in both ICI-LP and LP. Collectively, these data indicate that ICI-LP is not simply a more inflamed form of LP, but a distinct form of the disease with more prominent inflammatory perturbations within stromal and innate immune cell populations.

Autoimmune diseases result from immune responses against self-antigens but exhibit marked phenotypic diversity shaped by genetic and environmental factors. Genome-wide association studies (GWAS) have identified susceptibility loci that inform polygenic scores (PGS) for risk prediction. This study integrates phenotypic and genetic data from the UK Biobank(UKB) to characterize disease overlap, genetic heterogeneity, and shared biological mechanisms across autoimmune conditions. Comorbidity patterns were further assessed using patient records from UKB and the TriNetX(TNX). Phenotypic data from 502,371 UKB participants were used to evaluate diagnostic overlap, with a subset of 104,544 individuals analyzed for PGS distributions. Significant variants were identified using genome-wide thresholds, allele frequency, and predicted impact, and shared genes were subsequently mapped to pathways using Hallmark gene sets. Comorbidity across rare and common autoimmune diseases was assessed in the UKB and TNX using ICD-10 codes, focusing on White individuals (71,069,654 in TNX; 502,371 in UKB). Odds ratios for 15 diseases were estimated, and cross-cohort comparisons evaluated reproducibility and cohort-specific differences. PGS analyses revealed both shared and distinct genetic architectures, indicating partial genetic overlap and supporting poly-autoimmunity. Integration of common, rare and impactful variants identified both known and novel gene associations, while pathway analysis highlighted systemic and tissue-specific immune dysregulation. Cross-dataset comparisons confirmed consistent comorbidity patterns but underscored the impact of dataset-specific factors, emphasizing the need for standardized approaches in autoimmune disease research.

Exclusive Liquid Repellency Isolation (ELRi) is a novel, chip-free platform designed for efficient microscale immune cell isolation. Leveraging the inherent exclusive liquid repellency (ELR) properties of polypropylene tubes with an oil overlay, ELRi ensures that small sample volumes--as low as 8 L--have no contact with container walls, preventing cell loss. Here we describe ELRi and demonstrate magnetic bead-based isolation of diverse immune cells, including T-cells, and monocytes, from whole blood. The platforms utility is highlighted in its application to pediatric asthma research, where sample volume is highly restricted. It has been reported that the T-cell homing receptor CCR7 is downregulated in cells from asthmatic patients, but a direct functional link to impaired cell migration remains unconfirmed (1, 2). Using ELRi-isolated cells, we provide the first functional evidence that T-cells from asthmatic children exhibit significantly impaired chemotaxis toward the CCR7 ligand, CCL21. By simplifying RBC depletion and enabling such functional assays alongside RNA sequencing from the same tiny sample, ELRi overcomes the limitations of large-volume flow cytometry or cell-specific sorting methods. Easily integrated into lab workflows and scalable for various needs, ELRi facilitates more frequent, minimally invasive, and functionally informative immune profiling of restricted volume samples.

Aspergillus fumigatus is a ubiquitous environmental mould and a leading cause of chronic fungal-associated respiratory disease, yet the mechanisms by which persistent airway colonisation drives immune adaptation and lung pathology remain poorly understood. Progress in this area has been limited by the lack of in vivo models that recapitulate stable, non-invasive fungal persistence without immunosuppression. Here, we developed and optimised a murine model of chronic airway colonisation using agar bead-embedded A. fumigatus conidia delivered intratracheally. Embedding did not impair fungal germination or hyphal growth, and the agar matrix was immunologically inert, supporting its use as a neutral scaffold. This approach established stable fungal persistence in the airways for at least three weeks in immunocompetent mice without inducing invasive disease or systemic morbidity. Colonisation elicited a transient, airway-restricted innate immune response characterised by early neutrophil and monocyte recruitment and increased CXCL1, MIP-1, MIP-1{beta}, and TNF production, which resolved over time. Histopathological analysis revealed a progressive sequence of disease-relevant features, including initial immune containment, followed by mucus hypersecretion, and airway remodelling. At the adaptive level, persistent colonisation induced a dynamic T cell response that transitioned from an early polyfunctional profile to a sustained Th17-dominant phenotype. Importantly, application of this model in CFTR-deficient mice uncovered enhanced collagen deposition and fibrotic remodelling without altered fungal burden, demonstrating its utility in modelling disease-relevant outcomes in susceptible hosts. Together, this study establishes a robust and physiologically relevant platform for investigating host-fungal interactions during chronic airway colonisation. This model provides new opportunities to dissect mechanisms of immune adaptation, fungal persistence, and tissue remodelling, and to identify therapeutic strategies targeting chronic Aspergillus-associated lung disease.

Background & AimsCeliac disease (CeD) is an autoimmune disorder triggered by dietary gluten in genetically predisposed individuals, but environmental factors contributing to disease onset remain incompletely defined. Epidemiological studies implicate enterovirus infections as potential triggers. Here, we investigated the epithelial-intrinsic mechanisms by which coxsackievirus B1 (CVB1) infection may prime the intestine for CeD. MethodsHuman intestinal organoids were infected with CVB1 and analyzed using single-cell RNA sequencing to resolve lineage-specific responses. Interferon signaling and transglutaminase 2 (TG2) regulation were interrogated using type I interferon stimulation and pharmacologic JAK inhibition. ResultsCVB1 infection induced a robust epithelial antiviral program dominated by type I interferon signaling. This response was accompanied by marked upregulation of TG2 expression and enzymatic activity. Single-cell analysis localized TG2 induction to immature goblet-lineage cells, which exhibited strong interferon-stimulated gene activation and epithelial stress signatures. Mechanistically, IFN-/{beta} stimulation was sufficient to induce TG2 via JAK-STAT signaling, while JAK inhibition effectively suppressed both TG2 expression and activity. In parallel, CVB1 infection triggered coordinated mucin remodeling, including induction of MUC5AC, indicating interferon-linked epithelial reprogramming. Notably, these effects occurred independently of immune cell involvement, highlighting a cell-intrinsic pathway. ConclusionOur findings identify a direct epithelial mechanism linking enterovirus infection to TG2 activation via interferon-driven JAK-STAT signaling. This pathway provides a mechanistic bridge between viral infection and gluten peptide modification, a critical step in the onset of CeD. The reversibility of TG2 induction by JAK inhibition suggests a potential strategy to prevent virus-mediated priming of celiac disease.

Since the 1950s, micro- and nanoplastics (MNPs) have become omnipresent, representing a novel environmental hazard which continually deposits in our airways. Pulmonary macrophages (pMacs) orchestrate the balance between inflammation and tolerance required for homeostasis of the lung and are among the first immune cells to encounter inhaled MNPs. Yet, how pMacs react to plastic deposition in the lung and implications for disease remain unknown. Here, we exposed mice in vivo, human precision-cut lung slices (hPCLS) ex vivo, and monocyte-derived macrophages and cell lines to polystyrene MNPs in vitro. MNP deposition in the lung and extrapulmonary tissues was determined over a 1-week period and pMacs from MNP-laden lungs isolated for RNA-sequencing. We compared the effects of MNPs or diesel exhaust particulate exposures on hPCLS viability and metabolism, monocyte-derived macrophage transcription, and macrophage mitochondrial function, inflammation, and antigen presentation. MNPs readily translocated the lung and were observed in all organs examined within 1-day. pMacs from MNP-exposed mice expressed transcriptional pathways associated with endocrine system disorders, tissue remodeling, and malignant disease. Macrophage phagocytosis was impaired through decreased mitochondrial function which could be rescued pharmacologically. MNPs inhibited the ability of macrophages to effectively present OVA-antigen preventing TCR-specific activation, an effect that could be restored by blocking PD-1/PD-L1. These findings indicate that MNPs impair macrophages via unique mechanisms linking phagocytic and bioenergetic dysfunction. Loss of antigen-presenting capabilities in MNP-laden macrophages may compromise immunosurveillance. As such, MNPs have the potential to increase susceptibility to lung disease independent of the conventional mechanisms of inflammation and oxidative stress. Clinical relevanceO_LIBioaccumulation of micro- and nanoplastics in macrophages impairs their ability to function as antigen-presenting cells increasing susceptibility to pathogenic and malignant disease. C_LIO_LIPulmonary macrophages residing in micro- and nanoplastic laden lungs possess transcriptional profiles associated with endocrine system disorders, gastrointestinal disease, and cancers. C_LI

Interleukin-33 (IL-33) is a key cytokine in mast cell mediated immunity, promoting inflammatory cytokine production without inducing degranulation. Here, we compared IL-33 induced proteomic responses across three mast cell culture systems, Foetal Liver derived Mast Cells (FLMCs), Bone Marrow derived Mast Cells (BMMCs), and Peritoneal Mast Cells (PMCs), using quantitative data-independent acquisition mass spectrometry. Although baseline proteomes were largely conserved across all mast cell types, clear differences were observed between culture systems. PMCs exhibited a more mature phenotype, characterised by higher abundance of granule-associated proteins and lower levels of proteins involved in metabolism and translation. In contrast, FLMCs and BMMCs displayed higher levels of biosynthetic and metabolic machinery, consistent with a less differentiated state. IL-33 stimulation induced a conserved proteomic programme across all mast cell types, enriched for inflammatory signalling pathways, cytokine production, and enzymes involved in prostaglandin and biogenic amine biosynthesis. Pathway analysis demonstrated robust activation of nuclear factor {kappa}B (NF{kappa}B) associated signalling, with a relative enrichment of components linked to non-canonical NF{kappa}B signalling and tumour necrosis factor (TNF) receptor associated pathways. Mechanistically, IL-33 driven proteomic remodelling was strongly regulated by mitogen-activated protein kinase (MAPK) signalling. p38 MAPK emerged as the dominant regulator of the IL-33 response, with ERK1/2 contributing to a subset of induced proteins. These pathways differentially regulated key effector outputs, including IL-6, IL-9, IL-1 family cytokines, and enzymes required for prostaglandin, serotonin, and histamine biosynthesis. Together, these data define conserved IL-33 dependent inflammatory programmes across mast cell differentiation states and demonstrate how MAPK signalling pathways shape the composition of mast cell effector responses.

Long-lived plasma cells (LLPC) sustain humoral immunity but also contribute to the persistence of pathogenic autoantibodies in autoimmune diseases. New therapies targeting LLPC are therefore desirable. Recent studies have shown increased expression of Slc12a2, encoding the Na+ -K+ -Cl- cotransporter (NKCC1), in LLPC. This study investigated whether NKCC1 activity was required for plasma cell survival, persistence or secretion of antibodies. Across in vitro and in vivo settings, mouse plasma cell survival was undiminished by treatment with the NKCC1 inhibitor bumetanide. Acute in vivo bumetanide treatment did not diminish plasma cell numbers, nor show any demonstrable impact on the survival of phenotypically mature I-A/I-EloSLAMF6lo plasma cells. With genetic plasma cell timestamping, even the survival of persistent LLPC was unaffected by bumetanide. Plasma cell secretory capacity, assessed by measuring IgM and IgG2b secretion in culture over three days, was also unaltered by bumetanide. Overall, these results show that pharmacological inhibition of NKCC1 is not sufficient to impair plasma cell survival, persistence or antibody secretion. Despite elevated Slc12a2 mRNA expression in LLPC, NKCC1 alone does not represent a critical plasma cell survival pathway, highlighting the resilience of plasma cells and the challenges associated with therapeutically targeting LLPC.

WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome is a primary immunodeficiency caused by gain-of-function in CXCR4 chemokine receptor (CXCR4GOF) in response to its chemokine ligand CXCL12. The patients suffering from this syndrome display lymphopenia and neutropenia, and most of them show exacerbated susceptibility to human papillomavirus pathogenesis. In a mouse model harboring a WHIM-associated CXCR4 mutation and expressing HPV16 oncoproteins in keratinocytes, we previously reported reduced circulating plasmacytoid dendritic cells (pDCs), mirroring patients blood, and impaired dendritic cell (DC) trafficking from the skin to lymphoid organs, with the few migrating DCs displaying an overactivated phenotype. Given the promising results of CXCR4-targeted therapies in WHIM patients, we investigated whether and how the orally available CXCR4-specific antagonist, X4-136, affects DC localization, activation, and trafficking at the subset level, as well as skin immune landscape. CXCR4GOF inhibition corrected defects in circulating myeloid cells and pDCs, as well as in lymph node-resident DCs. Furthermore, it rescued skin DC migration to lymph nodes in WHIM mice, in a context- and subset-dependent manner, by promoting their activation and relocation within the dermis. Taken together, these findings indicate that inhibiting CXCR4GOF may restore skin immunity in WHIM syndrome by rescuing DC counts and functions. Key pointsO_LICXC R4 gain-of-function inhibition promotes subset-selective dermal dendritic cell migration to lymph nodes in a WHIM syndrome mouse model. C_LIO_LIInhibiting CXCR4 corrects migratory WHIM dendritic cell hyperactivation with subset-specific effects tied to the inflammatory context. C_LI

Neutrophils recruited to the airways are important for innate lung defense and can release neutrophil extracellular traps (NETs) to capture and eliminate microbes. While NETs are not abundant in healthy airways, uncontrolled NETosis is a known pathological feature and contributor to both chronic and acute respiratory diseases. Prior studies have shown that mucin glycoproteins secreted in the oral cavity and cervicovaginal tract can modulate NETosis, but it remains unknown whether mucins secreted in the respiratory tract influence NET formation. In these studies, we discovered that human airway mucus strongly inhibits NETosis in primary human neutrophils in a sialic acid dependent manner. In comparison, mucus produced by human airway epithelial cells genetically engineered to lack either MUC5B or MUC5AC secreted airway mucins showed a reduced ability to suppress NETosis. To assess how the lung microenvironment in obstructive lung diseases may influence mucus-dependent NET formation, we engineered a synthetic, mucin-laden hydrogel model with physical properties resembling that of mucus in a healthy lung and a disease-affected lung. When neutrophils were cultured on these gel substrates, we found that increasing gel stiffness led to a significantly greater extent of NETosis. Together these data demonstrate a new functional role of airway mucus in modulating neutrophil homeostasis in the respiratory tract and provide evidence that mucus dysfunction in disease can impair its ability to regulate NETosis.

High levels of IL-18 have been causally implicated in IBD risk and may represent a unique mechanism driving IBD yet to be therapeutically targeted. To identify individuals predisposed to increased levels of IL-18, we implemented a polygenic approach to predict IL-18 plasma protein levels. Using a dataset with over 50,000 individuals with both genetic and plasma protein levels from Olink, we developed a 27 SNP polygenic score that predicts IL-18 levels and IBD risk. Further, we identified a threshold to classify patients as 'IL-18 High' using a data-driven approach that optimized prediction of both IL-18 and IBD risk. We show that ~30% of the overall IBD patient population is 'IL-18 High', meaning a genetic predisposition towards higher protein levels. The IL-18 PGS and corresponding threshold have the potential to identify IBD patients with IL-18-driven IBD that may respond more effectively to a therapy targeting this mechanism.

BackgroundCTLA-4 haploinsufficiency (CHAI) and LRBA deficiency cause severe immune dysregulation including enteropathy. Abatacept, a CTLA-4-immunoglobulin fusion protein, targets the underlying pathway defect, but its impact on the gut microbiome remains undefined. MethodsWe performed longitudinal shotgun metagenomics (MetaPhlAn4/HUMAnN3) on stool samples from patients enrolled in the ABACHAI clinical trial, collected at pre-treatment baseline and months 3, 6, and 12. Healthy individuals from the same household served as controls. Compositional and functional microbiome changes were analyzed using linear mixed-effects models and MaAsLin3, and correlated with organ-specific CHAI Morbidity Scores. ResultsAt baseline, patients showed significantly reduced alpha diversity (Shannon index, p=0.0029) and distinct community composition (PERMANOVA p=0.0001) compared to healthy controls, characterised by enrichment of oral-associated taxa (Veillonella, Streptococcus, Lacrimispora) and depletion of butyrate-producing commensals (Ruminococcus, Oscillibacter, Dysosmobacter). Functionally, the baseline metagenome exhibited broad reductions in amino acid and SCFA biosynthesis alongside enrichment of purine salvage and folate pathways. During treatment, beta diversity shifted significantly with treatment duration (Aitchison PERMANOVA R2=0.103, p=0.015), with within-patient community turnover peaking at month 6 ({Delta}=0.216, p=0.006). Longitudinal analyses demonstrated progressive decreases in disease-enriched taxa (Veillonella, Lacrimispora) and recovery of commensals (Collinsella, Adlercreutzia). FDR-significant reductions in microbial folate and purine biosynthesis pathways were observed over the treatment course. Gut CHAI domain severity correlated inversely with butyrate-producer abundance and positively with oral taxon enrichment. ConclusionIn CTLA-4 pathway insufficiency patients, abatacept therapy is associated with an improvement of enteropathy and a progressive, measurable gut microbiome restructuring, positioning microbiome dynamics as a candidate biomarker of treatment response in this monogenic immune dysregulation disorder.

BackgroundGastrointestinal (GI) involvement in systemic sclerosis (SSc) affects up to 90% of patients and is a major driver of morbidity and mortality. Despite its clinical importance, GI disease in SSc is highly heterogeneous, with upper and lower GI manifestations representing distinct phenotypic extremes whose underlying immunologic basis remains poorly defined. MethodsWe performed unbiased, proteome-wide autoantibody profiling using a human protein microarray comprising >21,000 full-length proteins (>80% of the human proteome). Sera from patients with SSc and isolated upper GI dysmotility (n=23), isolated lower GI dysmotility (n=17), and non-SSc controls (n=20) were analyzed. Enriched autoantibodies were identified using Fishers exact test, and unsupervised clustering was applied to define serology-based patient subsets and relate immune signatures to clinical phenotypes. ResultsDistinct autoantibody profiles differentiated patients with upper versus lower GI disease. Upper GI-predominant SSc was characterized by enrichment of previously unreported autoantibodies, including those targeting TiSSc1/2 (newly identified proteins encoded within the MIRLET7BHG locus), FAM9C, SPATA20, FAM110D, EMILIN1, CARD14, SMN1, KCTD7, and PHYHD1, whereas lower GI disease was associated with antibodies against HAO2, KLHL7, SUFU, APPL1, BNIP2, UCHL3, ZNF385A, LIMD1, MAGEA9, and PPP2R3C. Serology-driven clustering identified four reproducible subgroups with distinct patterns of GI, pulmonary, vascular, and autonomic involvement, defining clinically meaningful disease phenotypes that extend beyond traditional anatomic classification. ConclusionsProteome-scale serological profiling reveals previously unrecognized autoimmune signatures underlying GI heterogeneity in SSc. These findings support a shift from anatomy-based to serology-defined classification of SSc GI disease and provide a foundation for biomarker development, patient stratification, and precision medicine approaches in this population.

Purpose: To characterize peripheral immune alterations in treated birdshot uveitis (BU) patients using high-dimensional mass cytometry and multiplex serology. Design: Cohort study. Subjects: 36 BU patients on immunomodulatory treatment (IMT) and 31 healthy controls (HCs). Methods: Detailed ophthalmologic examinations were performed, and peripheral blood and serum samples were collected for immune profiling using mass cytometry and multiplex cytokine analysis. Main Outcome Measures: Imaging-based indicators of ocular inflammation; peripheral immune cell frequencies; serum cytokine levels. Results: Compared to HCs, BU patients showed increased frequencies of Th17, CD146+ T cells, intermediate effector/central memory T cells co-expressing CXCR3 and CCR4, CD56dim NK cells and elevated IL-18 levels. Patients were clinically stratified by an expert ophthalmologist into three disease activity groups: Inactive, Active (comprising combinations of surface retina, deep retina and choroid activity) and Burned-out. Inactive patients harbored more quiescent effector T cells, e.g. Tim-3+ Tc17-Tc22 intermediates and more CD8+ TSCM, potentially representing a resting pool of autoimmune T cells. Active patients exhibited increased in vivo activation of relevant T cells, with stronger HLA-DR, CD38 or PD-1 expression, and highest levels of CD56dim NK cells. Immune profiles were also linked to treatment subgroups: csDMARDs (conventional synthetic disease-modifying antirheumatic drugs) were associated with higher CD56bright NK frequencies, and absence of therapy showed elevated PD-1/SLAMF7 Tc17+1 and PD-1CD57 CD8 TEMRA cells. IL-6R blockade (tocilizumab) resulted in loss of IL-6R T-cells accompanied by increased SLAMF7 T cells, due to epitope masking. Conclusions: Peripheral CyTOF profiling anchored to thorough clinical stratification revealed disease activity-associated immune signatures and therapy-associated imprints in BU.