Nature Immunology

Genome-wide association studies have identified thousands of variants associated with immune-related diseases, yet most lie in non-coding regions, complicating mechanistic interpretation. Regulatory quantitative trait loci (QTLs), such as expression QTLs (eQTLs) and chromatin accessibility QTLs (caQTLs), offer a powerful framework for prioritization and interpretation of these disease-associated genetic variants. When analyzed together, they offer deeper insights into the regulatory architecture underlying disease. We generated same-cell, single-cell multi-omics data, integrating transcriptomic and chromatin accessibility information, from 563,100 matched peripheral blood mononuclear cells collected from 264 individuals, either unstimulated or stimulated for 24h with C. albicans (CA). Across six major immune cell types, we mapped both cis-eQTLs and -caQTLs, identifying 1,571 eGenes and 28,862 caPeaks, with 41% and 11% showing a stimulation-dependent effect. Finally, to dissect the regulatory mechanisms underlying these QTL effects, we applied two complementary strategies: 1. overlapping caQTLs with eQTLs; 2. applying SCENIC+ to identify regulatory triplets containing a transcription factor, the chromatin region it may bind to and the candidate target genes it thereby may regulate. With the first approach, we identified 1,861 dual-acting QTLs. These dual-QTLs showed 1.9-fold stronger enrichment for immune-related disease associations than single-modality QTLs, highlighting their relevance for disease interpretation. With the second approach, we found 62,932 regulatory triplets, of which 1.7% were under genetic control. By then leveraging the SCENIC+-derived TF activity measurements we could study how genetic variants can rewire TF control of gene expression, ultimately shaping inter-individual variation in disease risk. Together, our network-based approach offers new insights into the cellular contexts and gene programs perturbed in disease, providing a foundation for prioritizing therapeutic targets and informing strategies for disease prevention.

Interleukin-1 (IL-1) is a central driver of autoinflammatory disease, yet IL-1 blockade often provides incomplete benefit in complex, neutrophil-driven conditions. Here we identify a licensing circuit in which common {gamma}-chain ({gamma}c) cytokines provide a redundant signal required for maximal IL-1-driven neutrophil inflammation. IL-1 and {gamma}c cytokines synergize to drive inflammatory cytokine production exceeding either stimulus alone, and these signals engage the MEK/ERK pathway, an effect substantially suppressed by pharmacological MEK inhibition. We validated this circuit in vivo in a mouse model of IL-1-driven neutrophil-dominant autoinflammation. Ablation of the shared {gamma}c receptor markedly prolonged survival and attenuated pathology, whereas deletion of individual {gamma}c cytokine pathways had no major effect--demonstrating in vivo necessity and functional redundancy. Analysis of public phospho-proteomic and transcriptomic datasets confirms MEK/ERK as a conserved neutrophil response to diverse inflammatory stimuli and coordinated IL-1, {gamma}c, and MEK/ERK activation in neutrophils from patients with systemic juvenile idiopathic arthritis (sJIA) and in lesional skin from hidradenitis suppurativa. Together, these findings define a signaling architecture in which redundant {gamma}c inputs enhance MEK/ERK-dependent inflammatory output, identify the {gamma}c receptor as an in vivo disease-modifying node, and position MEK/ERK as a mechanistically grounded therapeutic target. eTOC SummaryLorenzo et al. show that common {gamma}-chain ({gamma}c) cytokines provide redundant licensing signals that amplify IL-1-driven neutrophil inflammation through MEK/ERK convergence. Blocking any single {gamma}c cytokine fails to suppress disease, but ablating the shared {gamma}c receptor or inhibiting MEK/ERK markedly attenuates pathology, identifying these nodes as therapeutic targets in autoinflammatory disease.

CD4 T cells are orchestrators of the immune system with diverse effector functions. Their full molecular diversity remains unclear due to the lack of a unified framework. Within the immgenT project, we profiled RNA, surface markers, and TCR clonotypes in conventional CD4T cells across >700 samples. Integration with a joint RNA-protein deep generative model revealed an ensemble of 20 CD4 states that account for all cells across tissues and challenges. Small, highly polarized clusters ("tips") that evoke Th1, Th2, Th17, and Tfh states co-exist with a majority of activated cells with mixed programs occupying "midland" states. Unlike CD8 T cells, memory CD4 cells largely mapped to the same states as effectors. Resting states proved quite diverse, and we uncovered unexpected similarities between Tfh and chronically-stimulated states. Together, immgenT provides a unified molecular reference for CD4 T cell diversity.

Tumor-reactive T cells (TRTs) are critical for anti-tumor immunity but are incompletely captured by current assays, which fail to reproduce tumor-specific antigen diversity. Here, we show that multiplex functional profiling of patient-derived tumor organoid-T cell co-cultures (PDOTs) enables robust identification of TRTs across CD8, CD4, and double-negative (DN) T cell populations. Single activation markers underestimated TRT responses, whereas integrated analysis revealed broader functional repertoire. MHCI blockade abrogated CD8 and DN TRT responses while preserving CD4 reactivity, supporting antigen-dependent recognition across T cell lineages. Tumor PDO expressed MHCI and MHCII, and PDOTs enabled generation and detection of TRTs from peripheral blood. PD1 blockade induced heterogeneous responses, enhancing CD8 and DN activity and unexpectedly augmenting CD4 reactivity. PDOTs further identified additional inhibitory pathways whose therapeutic targeting in combination with PD1 blockade increased TRT responses. These findings establish PDOTs as a platform to identify TRTs and functionally stratify patient-specific tumor-T cell responses to checkpoint immunotherapy.

Juvenile dermatomyositis (JDM) is characterized by a type I interferon (IFN-I) signature associated with disease activity. We previously identified a link between SARS-CoV-2 infection and the onset or relapse of JDM. Here, we show that newly diagnosed JDM patients display an overexpression of IFIH1 (encoding MDA5 protein) at baseline, coupled with an altered response to dsRNA stimulation at proteomic and transcriptomic levels, indicating abnormal activation of this antiviral sensing pathway. Single-cell transcriptomic and chromatin accessibility profiling of peripheral blood mononuclear cells (PBMCs) further revealed myeloid-specific enrichment of interferon-stimulated genes (ISGs) and preferential disruption of this pathway at disease onset, supporting a dysregulated IFN-I state in this cell type. We identified SARS-CoV-2 RNA in muscle biopsies of two Covid-19 pandemic-onset JDM patients, strongly implicating viral infection as a potential trigger of the dysregulated MDA5 immune response. To extend these observations beyond SARS-CoV-2, we screened two independent retrospective cohorts for antibodies against 27 common childhood infections. In our discovery cohort JDM patients showed significantly increased exposure to 4 RNA viruses in line with our immunological findings. Increased exposure to RSV B was confirmed in an independent replication cohort supporting a robust association with JDM pathophysiology. Together, these findings integrate systemic, single-cell, and tissue-level analyses implicating RNA viral infection and biased antiviral sensing in shaping IFN-I responses at JDM onset, providing mechanistic insight into environmentally triggered pathogenesis. One sentence summaryType I interferon dysregulation at juvenile dermatomyositis onset implicates altered dsRNA sensing and RNA viral exposure as potential disease triggers.

Immune dysfunction is a major driver of morbidity and mortality in critical illness syndromes including sepsis. Specifically, CD8+ T cell dysfunction has been linked to organ failure and death. To characterize the immune substructure of circulating CD8+ T cells in critical illness at high dimension, we used single-cell RNA sequencing of peripheral blood CD8+ T cells from 38 critically ill patients and 9 healthy controls. We annotated seven CD8+ T cell clusters, which included a CD8+ effector subset, termed T effector state 2 (TEff-2), that was only present in critically ill patients and associated with more severe respiratory failure and higher mortality. TEff-2 showed effector activation and inflammatory stress conditioning yet had markedly reduced metabolic transcripts without canonical features of exhaustion. Trajectory analyses positioned TEff-2 as a terminal CD8+ T effector cell fate driven in part by DDIT4 and DUSP1, which negatively regulate mTOR and MAPK signaling, respectively. Interestingly, this transcriptional program was indistinguishable by classical protein cytometry methods. These results, including the mortality association, were validated in a larger (n=91) independent external cohort of critically ill patients with sepsis. In summary, TEff-2 represents a latent transcriptional program that delineates a clinically high-risk CD8+ T cell state in critical illness.

Interferon-{gamma} (IFN{gamma}) signaling is prominent in inflammatory CNS microenvironments across many neurological disorders, but the neuronal peptides presented on HLA class I under these conditions and their functional consequences for CD8+ T cells remain incompletely defined. Here we combine human iPSC-derived human neural aggregates (HNAs), HLA class I immunoprecipitation coupled to LC-MS/MS immunopeptidomics, and microfluidic co-culture assays to map IFN{gamma}-induced neuronal antigen presentation and test antigen-specific cytotoxicity. IFN{gamma} stimulation induced robust HLA class I expression in HNAs and enabled recovery of a canonical 8-12-mer class I ligandome enriched for 9-mers. Neuron-restricted expression of a synapsin-driven polyepitope cassette yielded presentation of defined neoantigen 9-mer peptides on donor HLA class I molecules and, in the presence of IFN{gamma}, elicited activation of autologous antigen-specific CD8+ T cells and consequent antigen-dependent neurite injury. Across four donors, comparative immunopeptidomics identified large IFN{gamma}-unique neural peptide repertoires distinct from matched fibroblasts and revealed a consistent enrichment of predicted high-affinity binders on HLA-B allotypes. Finally, {beta}2-microglobulin deletion ablated peptide recovery, and neuron-restricted {beta}2-microglobulin reconstitution enabled identification of neuron-derived peptides, including peptides derived from neurofilament light (NEFL) that were shared across donors and presented on multiple HLA allotypes. Together, these data provide an integrated platform for neuronal autoantigen discovery and functional validation and support a model in which IFN{gamma}-driven neuronal HLA class I presentation creates an HLA-B-weighted epitope landscape that can be recognized by autoreactive cytotoxic CD8+ T cells.

Type I interferons (IFN-I) are critical for antiviral defense but can drive severe pathology when dysregulated. Excess IFN-I is associated with prominent neutrophil accumulation; however, the contribution of neutrophils to IFN-I overproduction remains underexplored. In all cell types previously studied, IFN-I is synthesized de novo following sensing of microbial or host-derived inflammatory stimuli. Contrary to this paradigm, we find that neutrophils express IFN during development and store it in the nucleolus, a membrane-less intranuclear condensate classically functioning in ribosome biogenesis. TLR-mediated bacterial sensing induces a nucleolar stress response in neutrophils that triggers rapid release of nucleoli-stored IFN independent of de novo protein synthesis. These findings reveal roles for the neutrophil nucleolus in IFN-I storage and secretion, identify the first naturally occurring immunoregulatory function of nucleolar stress, and provide insight into the relationship between detrimental IFN-I levels and neutrophil accumulation.

CD8 T cells mediate protective immune responses. However, persisting antigens such as chronic viruses or tumors redirect CD8 T cell differentiation to a sub-optimal, epigenetically defined state called exhaustion. Exhausted T cells (TEX) lose their ability to persist long-term and to initiate functional memory responses. Checkpoint inhibitor blockade temporarily restores effector functions, but immune reinvigoration is not long-lasting, due to the epigenetic stability of TEX. Therefore, epigenetic reprogramming of TEX leading to durable T cell responses is essential to improve disease control. Here, we demonstrate that a single microRNA (miR), miR-29a, epigenetically re-directs TEX differentiation and preserves TEX into a stem-like state, leading to long-term persisting progenitor TEX. MiR-29a rewires epigenetic maintenance programs, including downregulation of key exhaustion-associated regulators (Dnmt1, Dnmt3a, and Dnmt3b), alongside increased expression of progenitor- and stemness-associated genes such as Tcf7 and Il7r. These reprogrammed CD8 T cells are more sensitive to PD-L1 checkpoint blockade. Ectopic expression of miR-29a combined with aPD-L1 treatments enhances effector responses, while preserving T cell stemness. Together, our findings suggest that miR-29a can be leveraged to overcome current barriers to immune checkpoint blockade. HighlightsO_LIMiR-29a rewires key exhaustion-associated epigenetic maintenance programs, while enhancing stemness-associated transcriptional circuits. C_LIO_LIMiR-29a drives extensive remodeling of accessible chromatin in TEX. C_LIO_LIMiR-29a preserves newly generated progenitor TEX in a durable, epigenetically defined stem-like state with increased effector function. C_LIO_LIMiR-29a synergizes with aPD-L1; while miR-29a preserves progenitor TEX state, addition of aPD-L1 enhances the cytotoxic potential of these progenitor TEX cells. C_LI

Pneumonia is the leading cause of death from infectious disease worldwide. The diagnosis and treatment of patients with pneumonia lag behind other major conditions, relying on syndromic definitions that lack molecular resolution and ignore underlying endotypes. We sought to test the hypothesis that dynamic pathogen-specific host responses in the alveolar space represent distinct pneumonia endotypes linked to different clinical features and outcomes. We prospectively enrolled a cohort of 690 patients (including immunocompromised patients) with known or suspected pneumonia receiving mechanical ventilation in whom the etiology of pneumonia was determined by gold-standard analysis of distal lung fluid obtained by bronchoalveolar lavage (BAL) combined with clinical adjudication. From these patients, we analyzed 792 BAL fluid samples, including 310 serial samples, using flow cytometry (482 patients) and single-cell RNA-sequencing (170 patients; 263 samples, complemented by 9 healthy controls and 25 post-COVID-19 patients, yielding [~]2.4 million single cells across 28 cell types), and extracted daily clinical data from the electronic health record (>15,000 patient-days). We used machine learning models to identify pathogen-specific host responses in the transcriptome of alveolar immune cells that were associated with changes in alveolar cell abundance and clinical features. Our results suggest that therapeutic strategies for pneumonia should be individualized to specific host-pathogen interactions.

Whereas cellular stress responses are well defined, tissue-level stress remains poorly understood. Proteases are among the most widespread enzymes, and excessive proteolytic activity drives diseases such as arthritis and chronic obstructive pulmonary disease, yet unifying features of this stress are unclear. Here, using the lung and diverse proteases, we identify a conserved injury signature of proteolytic stress marked by vascular disruption, red blood cell extravasation, and heme release that triggers oxidative stress. We show that alveolar macrophages act as primary sensors of this stress response, activating NRF2-dependent heme detoxification program and fibroblasts produce protease inhibitors to limit damage. Repeated exposure to proteolytic stress induces tissue adaptation and protects against subsequent injury and infection. These findings define a unifying framework for tissue-level proteolytic stress sensing and adaptation.

Regulatory T (Treg) cells maintain immune tolerance via contact-dependent inhibition and soluble mediators. While canonical suppressive mechanisms are well characterized, their hierarchical spatiotemporal organization remains unclear. We previously showed Foxp3 represses ER Ca2+ channel RyR2, reducing cytoplasmic Ca2+ to inactivate m-Calpain (Calpain-2) and stabilize high-affinity LFA-1-mediated Treg-dendritic cell (DC) adhesion--an early step blocking DC antigen presentation. Using m-Calpain as a molecular switch, we generated mechanically deficient Tregs (TregFD) with constitutively active m-Calpain that abrogated high-force Treg-DC adhesion. TregFD retained a near-wild-type transcriptome (differential expression limited to adhesion pathways), yet failed to suppress autoimmunity or DC-driven T cell proliferation. Stable adhesion was required for localized TGF-{beta}/IL-10 delivery to DCs. Single-cell RNA sequencing of rescued Scurfy mouse lymphoid tissues revealed organ-specific division of labor: non-mechanical modules support homeostasis/tissue repair, while mechanical modules dominate epithelial barrier/antigen presentation suppression. Combined TregFD and RyR2-deficient Tconv transfer restored wild-type Treg activity, demonstrating module synergism. These findings establish a mechanical force-centered, two-tiered hierarchical model of Treg suppression, providing a framework for targeting Treg mechanics in autoimmunity and inflammation.

Immune responses to infection and vaccination exhibit diversity between individuals that can be shaped by differences in their immune cell landscapes and the signalling, transcriptional, and genetic mechanisms that coordinate immune cell function. Specific antibody deficiency (SAD) and common variable immunodeficiency (CVID) are common forms of predominantly antibody deficiencies that result in poor responses to vaccination. While molecular and cellular causes of the immune dysfunction and poor vaccination responses for individuals with CVID have been reported, immune cell or molecular defects have not yet been identified in SAD. Here, we have used single-cell multi-omics to define the cellular landscapes, transcriptional states, adaptive immune repertoires and protein expression of patients with SAD and CVID before and after polysaccharide vaccination. We discovered that while SAD and CVID exhibit overlapping immune defects, including accumulation of exhausted NK memory cells and dysregulated expression of genes that mediate lipopolysaccharide sensing and clearance by monocytes, individuals with SAD have a unique expansion of cytotoxic CD4+ T cells that correlates with reduced regulatory T cells. In response to vaccination, we observed rapid changes in gene expression associated with lipopolysaccharide responses by monocytes and NF-kB pathway activation in B cells, and an apparent expansion of a CD95+ class-switched memory B cell population that does not occur in patients with lower antigen-specific responses. Together, our findings reveal cellular and molecular factors that underpin variability in vaccine responses and define SAD in a broader spectrum of immune dysfunction.

Blocking the programmed cell death 1 (PD-1) pathway using monoclonal antibodies reinvigorates exhausted T cells (Tex), enhancing control of chronic viral infections and cancer. Considerable effort has focused on evaluating different PD-1 blockade agents in preclinical and clinical cancer settings, but relatively little information exists on how to optimize the pharmacodynamic effects of PD-1 pathway blockade on reinvigorating Tex. To address this question, we performed longitudinal tracking of Tex reinvigoration during chronic infection with lymphocytic choriomeningitis virus (LCMV) following different regimens of PD-1 blockade. We compared single-cycle (2 weeks of treatment), long-term continuous PD-1 pathway blockade (i.e. 3 months), or blockade followed by a drug holiday and then re-blockade (intermittent treatment). These studies revealed little benefit of continuous versus single-cycle PD-1 blockade, with both resulting in a single peak of Tex reinvigoration and similar effects on viral replication. In contrast, intermittent blockade resulted in a new cycle of secondary Tex reinvigoration upon redosing after a washout and this secondary Tex reinvigoration improved disease control. Mechanistically, long-term blockade eroded the ability of Tex progenitor cells (Tpex) to give rise to downstream, more functional Tex intermediate (Tex-Int) progeny, whereas the drug holiday restored this Tpex proliferative and differentiation capacity. Tpex from long-term treated mice showed evidence of adaptive resistance and additional layers of negative regulation, including sustained expression of the inhibitory receptor CD22. Indeed, co-blockade of PD-1 and CD22 using combination antibodies or bispecific antibody approaches improved disease control and reinvigoration of Tex. These data have implications for clinical immune pharmacodynamics of PD-1 blockade and provide insights into the biology of Tex reinvigoration. One Sentence SummaryModifying the immunopharmacology of PD-1 blockade reveals a benefit of a drug holiday and identifies mechanisms of Tex progenitor deficiency provoked by prolonged loss of PD-1 signals including the inhibitory receptor CD22.

Despite the clinical success of cancer immunotherapies, the cellular interactions driving tumor regression remain incompletely understood. Here, we investigated the dynamic remodeling of the tumor immune microenvironment during regression of transplanted PyMT mammary tumors following STING agonist treatment. Using scRNA-seq of sorted CD8+ T cells and myeloid cells, combined with imaging approaches, we identified major changes in both lymphoid and myeloid compartments during tumor regression. Regressing tumors showed a transient accumulation of Ly6Chi monocyte populations associated with a decline in macrophage subsets, while effector and memory CD8+ T-cell populations increased at the expense of exhausted T cells. Interaction analyses predicted enhanced chemotactic and adhesion interactions between CXCL9+ Ly6Chi monocytes and effector CD8+ T cells. Consistently, dynamic imaging revealed increased CD8+ T-cell motility and infiltration into tumor cores following treatment. In particular, CXCR6+ effector CD8+ T cells transiently accumulated within tumor islets during regression before relocalizing to stromal regions. Together, these findings reveal a coordinated spatiotemporal remodeling of myeloid and CD8+ T-cell populations during immunotherapy-induced tumor regression and highlight cooperative interactions that may promote durable anti-tumor immunity.

Resistance to immune checkpoint inhibitors (ICIs) remains a major challenge in oncology, yet the mechanisms that selectively disable activating pathways are poorly defined. Here, we identify tumor-derived soluble CD155 (sCD155) as a systemic checkpoint that rewires DNAM-1 signaling to drive immunotherapy resistance. High plasma sCD155 levels correlate with impaired anti-PD-1 responses in patients with non-small cell lung cancer. Mechanistically, sCD155 selectively suppresses DNAM-1-dependent activation of CD8+ T and NK cells, uncoupling ICIs from cytotoxic function. Intriguingly, a selective anti-sCD155 monoclonal antibody does not neutralize the ligand, but rather converts it into an activating scaffold. This complex induces Fc{gamma}R-anchored DNAM-1 microcluster formation and robust downstream signaling, effectively switching the checkpoint into a co-stimulatory signal. This reprogramming restores CTL function, suppresses metastasis, and augments PD-1/TIGIT blockade to achieve durable immunity. Our findings establish antibody-mediated receptor architecture rewiring as a therapeutic principle to overcome cancer immune resistance.

B cell activation and differentiation into antibody-secreting cells require extensive metabolic and epigenetic remodeling, yet the molecular mechanisms that integrate these programs remain incompletely understood. ATP-citrate lyase (ACLY) links glucose metabolism to acetyl-CoA production, supporting lipid biosynthesis and protein acetylation. However, its role in humoral immunity has not been fully defined. Here, using genetic and integrated multi-omics approaches, we show that B cell activation is accompanied by coordinated metabolic, transcriptional, and epigenetic reprograming. Although ACLY is dispensable for B cell development and homeostasis, it is required to establish chromatin accessibility programs in activated B cells, with a more pronounced impact on the epigenetic landscape than on transcriptional output. ACLY-deficient B cells exhibit profound defects in TLR and BCR elicited activation, survival and metabolic fitness ex vivo. In vivo, B cell-intrinsic loss of ACLY results in impaired antigen-specific antibody production, associated with reduced germinal center and plasmablast formation, but normal homeostatic proliferation. Deletion of ACLY after B cell activation reduces plasmablast generation in vivo, indicating a continued requirement for ACLY beyond the initial activation phase. Together, these findings identify ACLY as a central regulator that links metabolism to epigenetic programing that supports B cell activation and humoral immunity.

Mucosal IgA is critical for controlling the microbiota and preventing pathogenic infection of the epithelium. The innate signals that regulate the generation of IgA remain poorly defined. Here, we identified TRIF and IL-1R1 as immune checkpoints for intestinal IgA production. In the absence of infection, Trif-/- and Il1r1-/- mice exhibited markedly elevated stool IgA and IgA-bound commensals. We show that IL-1R1 restricts IgA class-switching in a B cell-intrinsic manner, while TRIF acts extrinsically of B cells and shapes the Peyers patch microenvironment. Loss of either Trif or Il1r1 enhanced retinoic acid metabolism and allowed premature Ccnd3 upregulation in naive B cells, favoring both IgA class-switching and differentiation into germinal center B cells. During oral vaccination, the absence or blockade of the TRIF/IL-1R1 pathway increased antigen-specific IgA production without affecting seric antigen-specific IgG levels. These findings unveil novel and local signaling targets to promote robust antigen-specific mucosal immunity.

Many vaccine regimens involve delivery of multiple doses to the same anatomical site, such that booster doses frequently encounter germinal centers (GCs) still active from prior immunization. The consequences of this "GC refueling" to B cell clonality have not been systematically investigated. Using mouse models of mRNA-LNP vaccination combined with multicolor fate-mapping, longitudinal GC imaging, and immunoglobulin sequencing, we show that refueling triggers clonal burst-type expansion of GC-resident B cells, rather than recruiting local memory, resulting in marked focusing of GCs on the descendants of individual B cells. Refueling with a drifted antigen led to limited but detectable retraining of primary-cohort clones, although most variant-specific responses in this setting arose from newly recruited naive B cells. These findings identify GC refueling as a distinct mode of vaccine response with implications for sequential immunization strategies against rapidly evolving pathogens.

The gut-joint axis describes how impaired intestinal epithelial function and increased gut permeability allow luminal factors to enter circulation. This can drive inflammation in Rheumatoid Arthritis, a chronic condition affecting the joint with systemic features. What mechanisms contribute to disease persistence are, as yet, incompletely understood. In health, extensively Oglycosylated intestinal mucins are central to epithelial protection and immune homeostasis; however, whether mucin glycosylation is altered during arthritis has not been addressed. Here, we investigated whether arthritisassociated inflammation alters mucin Oglycosylation, potentially compromising intestinal barrier function. Using a collageninduced arthritis mouse model, we combined epithelial transcriptomics, mass spectrometry-based glycomics, and imaging approaches to profile intestinal glycosylation. We identified distinct glycan remodeling in the colon, characterized by reduced fucosylation, while the ileum remained largely unaffected. In vitro studies using 3D human epithelial cultures further demonstrated that inflammatory cues, particularly from TNFactivated stromal cells, are sufficient to reduce epithelial fucosylation. Together, these findings identify a stromal-inflammatory mechanism that disrupts mucin glycosylation during arthritis. Loss of colonic fucosylation emerges as a novel element of inflammatory arthritis, providing an additional mechanistic link between intestinal inflammation and fibroblast-dependent modulation of the tissue microenvironment.