Journal of Autoimmunity

Women are predisposed to systemic lupus erythematosus (SLE) with a prevalence ratio of up to 9:1 over men. Multiple mouse strains including NZM2328 exhibit strong female dominance in developing spontaneous lupus as in humans with SLE. While lupus-prone mice can develop disease under germ free (GF) condition, the role of gut microbiota in female bias for lupus nephritis is not investigated systematically. Here, using specific pathogen free (SPF) and GF NZM2328 mice, and employing microbiota-depletion and microbial-association strategies, we show that microbiota influences lupus-like disease outcomes differently in males and females. Female NZM2328 mice with intact microbiota presents higher inflammation factor expression, including X-chromosome linked TLRs, in the distal gut and systemic compartments, and higher activation of genes and biological pathways such as neutrophil extracellular trap (NET) formation and complement and coagulation cascade (CCC) pathways, associating with their higher disease susceptibility. Gut microbiota-depletion as well as GF derivation eliminated not only the modest differences in the serum and fecal antibody levels and nAg reactivity, but also the gender bias in the timing of clinical stage disease onset as well as systemic NET and CCC pathway activation. Reciprocally, conventionalization of GF NZM2328 mice at juvenile age restored the female bias in intestinal and systemic autoantibody levels, pro-inflammatory immune pathway activation, and the timing of clinical stage disease onset. Overall, our observations show that, while genetic susceptibility appears to be the cause of lupus-like disease in NZM2328 mice, differential activation of NET and CCC pathways in males and females upon exposure to gut microbes, in combination with host-factors, causes gender bias in disease outcomes. We conclude that microbiota exposure-dependent protection of males and overactivation of NET and CCC pathways in females could be contributing to the female bias in lupus-like disease in NZM2328 mice.

Objective: To determine whether autoantibodies are present in giant cell arteritis (GCA) using a high-dimensional autoantibody array. Methods: Serum was collected from patients with GCA (n=20), other related vascular inflammatory diseases (Takayasu arteritis n=12, IgG4-RD n=5, Behcet's disease n=6), SLE (n=5) and healthy controls (n=12). Autoantibodies to 15,312 protein targets were measured using the GeneCopeia OmicsArray proteomic antigen microarray panel. Results: Differential abundance analysis revealed no autoantibodies significantly elevated in GCA or other related vascular inflammatory diseases. In contrast, the SLE group showed a strong and promiscuous autoantibody response, with 175 significantly associated autoantibodies (Benjamini-Hochberg-adjusted P <0.05). Conclusions: No autoantibodies were significantly elevated in GCA. We identified known and novel autoantibodies in SLE.

Recent epidemiologic studies indicate that adult-onset type 1 diabetes (AOT1D) is more common than childhood-onset type 1 diabetes, yet it remains clinically underrecognized. Because little is known about the emergence of islet autoantibodies in AOT1D, we conducted a retrospective study using electronic medical records from the United States Military Health System and longitudinal serum samples from 169 individuals with AOT1D and 40 healthy controls obtained from the Department of Defense Serum Repository. Among 643 prediagnostic samples from individuals with AOT1D, IA-2 autoantibodies were the most prevalent (50%), followed by GADA (46%), IA-2{beta} (34%), ZnT8-R (27%), and ZnT8-W (15%). Overall, 85% (144/169) of subjects were seropositive for at least one autoantibody prior to diagnosis. Analysis of the earliest available sample from all of the AOT1D cases, grouped into 5-year intervals preceding diagnosis, demonstrated a progressive increase in seropositivity over time: 38% of subjects were seropositive more than 20 years before diagnosis, increasing to 44% at 20-15 years, 59% at 15-10 years, 73% at 10-5 years, and 91% within 5 years of diagnosis. Among the 144 seropositive individuals, positivity for two or more autoantibodies was the most common pattern, occurring in 50% (72/144) of cases. Isolated GADA positivity (22%) and isolated IA-2/IA-2{beta} positivity (24%) occurred at similar frequencies, whereas isolated ZnT8 positivity was uncommon (4%). Temporal analysis showed that isolated GADA positivity appeared earliest, with a median onset of 7.9 years before diagnosis, whereas multiple-autoantibody positivity, IA-2 positivity, and ZnT8 positivity emerged later, with median onsets of 4.6, 4.5, and 1.9 years before diagnosis, respectively. These findings extend observations from pediatric type 1 diabetes to adults and demonstrate that AOT1D-associated autoimmunity often begins decades before clinical diagnosis, highlighting a potentially important window for risk stratification and preventive intervention.

Type 1 diabetes (T1D) is caused by T cell-mediated autoimmune destruction of insulin-producing islet beta-cells. Treatment with T-cell depleting therapies delays the progression of stage 2 and 3 T1D, but these agents exert broad immunosuppressive effects on T cell populations, including T regulatory cells (Tregs), which are key in promoting immune tolerance. We evaluated non-obese diabetic (NOD) mice and recently diagnosed T1D patients and identified CD38 as a marker for pathogenic T cell populations. Using adoptive T-cell transfer in Recombination Activating Gene 1 knockout NOD mice and in a humanized mouse model of autoimmune diabetes, we demonstrated that CD38-expressing autoreactive T cells drive diabetes pathogenesis. Furthermore, we found that selective depletion of CD38+ cells, using an anti-CD38 monoclonal antibody (mAb), prevents insulitis and diabetes onset without depleting CD4+CD25+ Tregs. Administration of anti-CD38 mAb did not adversely affect islet function and may selectively eliminate immunogenic senescent islet beta-cells. These results support the strategy of selectively depleting diabetogenic T cells using an anti-CD38 mAb to treat T1D and restore immune tolerance. Therefore, transient depletion of autoreactive T cells using anti-CD38 mAb may provide a novel strategy to prevent or abrogate autoimmunity in T1D.

BackgroundSevere eosinophilic asthma (SEA), eosinophilic granulomatosis with polyangiitis (EGPA) and nasal polyposis (NP) are immune-mediated diseases characterised by eosinophilic inflammation. However, there is also increasing interest in the potential pathological roles of autoantibodies in these diseases. Understanding their B cell receptor (BCR) repertoires may provide valuable insights into disease mechanisms, and potential role of B cells in their pathology. MethodsWe conducted BCR repertoire sequencing using peripheral blood from 43 patients, comprising SEA with nasal polyps (SEA+NP), SEA without nasal polyps (SEA-NP), and EGPA, along with 16 healthy controls (HCs). ResultsCompared to HCs, patients with EGPA exhibited increased relative proportions of IgA1, IgG1, IgG2, and IgG4 subclasses. Similarly, SEA-NP patients demonstrated significantly high proportion of IgG2 sequences. Notably, the IgG4 subclass was significantly elevated across all patient groups compared to HCs. Patients receiving anti-IL-5/5R biologic treatments showed increased relative proportions of IgA2 and IgG2 subclasses compared to untreated patients. Some variation across participant groups in mean somatic hypermutation and mutation frequency was evident. 1,508 clones shared across patients, but not healthy controls, were evident though the majority showed low clonal expansion. Nevertheless, a few shared clones did show either high prevalence across patients and/or higher clonal expansion. ConclusionChanges in BCR repertoires in SEA/EGPA are consistent with a pattern of a more mature B cell component in the periphery and with the T2 inflammatory response observed in SEA and EGPA. BCR clonotypes shared across patients were evident, however, whether such clonotypes are pathological in SEA/EGPA requires further investigation.

Psoriatic disease (PsD) is associated with metabolic dysfunction-associated steatotic liver disease (MASLD), but the hepatic effects of biologic therapies are unclear. We evaluated paired liver MRI and multi-modal immunoprofiling in PsD patients initiating new systemic therapy. COLIPSO is a prospective cohort of adults with moderate-to-severe psoriasis or psoriatic arthritis (PsA) starting a new conventional synthetic or biologic disease-modifying antirheumatic drug (DMARD). Liver MRI was performed at baseline and ~6 months. A subset of participants with PsA underwent peripheral blood flow cytometry and single-cell RNA sequencing (scRNAseq). Primary outcomes were within-subject change in quantitative MRI measures of liver disease activity and fat content (iron-corrected T1 [cT1] and proton density fat fraction [PDFF]). Bayesian models were used. Thirty-five participants (mean age 50 +/- 13 years; 61% male) were followed for ~29 weeks. Baseline disease activity was moderate (mean DAPSA 29) and 40% had MASLD. IL 17 inhibitors (IL-17i) improved PDFF (-1.58 +/- 1.61%) and cT1(-43.6 +/- 52.7ms), whereas TNFi showed little change. Compared with csDMARD, IL 17i improved PDFF (probability of direction [pd] 89%) and cT1 (pd 93%), which was not seen with TNFi. Flow cytometry (n=17) linked baseline gamma delta T-cell and ThGM-CSF T-cell abundance with cT1 and PDFF. scRNAseq highlighted baseline transcriptomic signatures in MAIT cells associated with cT1 and PDFF. Naive T-cell RNA signatures at baseline were associated with MRI improvements. In PsD, only IL-17i were associated with improved liver disease in addition to improving clinical PsD outcomes. T-cell subtypes bridging innate and adaptive immunity were associated with liver disease features.

Background: Psoriatic arthritis (PsA) is an inflammatory condition involving joints, tendon-bone entheses and synovium that can develop in individuals with psoriasis. Early, accurate clinical diagnosis remains difficult. Extracellular vesicles (EVs) carry proteins and miRNAs that Methods: PubMed and Embase were searched from inception through May 21st, 2026, and human studies examining EV-associated protein or miRNA biomarkers in PsA and related psoriatic or inflammatory diseases were included, with risk of bias assessed using a modified Newcastle-Ottawa Scale and diagnostic accuracy summarized using HSROC/BRMA models when data were sufficient. Results: Seven studies met the inclusion criteria, including 119 individuals with PsA (weighted mean age: 49.8 years; 43.7% female), 205 individuals with non-PsA psoriasis (weighted mean age: 46.4 years; female %: NA), 55 controls (weighted mean age: 44.5 years; 38.2% female), and 50 individuals with other inflammatory joint disorders (weighted mean age: 58.0 years; 58.0% female). EV-associated protein markers demonstrated heterogeneous findings related to immune, vascular, inflammatory, and osteoimmunological signaling. Only 4.2% (4/95) of miRNAs were consistently identified across studies comparing PsA with non-PsA psoriasis, with lower overlap (1.5%, 1/67) in studies comparing PsA with controls. ROC meta-analysis suggested preliminary diagnostic potential, particularly for distinguishing PsA from non-PsA psoriasis, although evidence was constrained by small study numbers. Conclusions: EV-associated proteins and miRNAs are potential biomarker candidates for PsA, reflecting inflammatory, vascular, and osteoimmunological processes underlying disease pathophysiology. However, current evidence remains preliminary and limited by small cohorts, methodological heterogeneity, and inconsistent reporting across studies.

Background: Anti-synthetase syndrome (ASyS) is a subgroup of idiopathic inflammatory myopathies that is increasingly recognized as a distinct entity with features of myositis, interstitial lung disease, inflammatory arthritis, and Raynaud phenomenon. Co-reactivity with anti-Ro-52, an antibody directed against the Ro-52 E3 ubiquitin ligase, has been shown to be associated with progressive interstitial lung disease within this patient population. However, less is known regarding the association of anti-Ro-52 positivity with cardiovascular outcomes. Methods: A sub-cohort of patients with anti-synthetase antibodies at a large single institution center was retrospectively analyzed to define presence of anti-Ro-52 positivity (defined as anti-Ro-52 titer greater than or equal to 11 utilizing the line immunoblot platform, Euroline Autoimmune Inflammatory Myopathies, EuroImmun Diagnostics, Lubeck, Germany). Patients who did not meet 2017 ACR/EULAR classification criteria for idiopathic inflammatory myopathies were excluded from the final analysis. Cardiovascular outcomes ascertained via retrospective chart review included atrial fibrillation, left bundle branch block, right bundle branch block, pulmonary hypertension (confirmed via right heart catheterization), heart failure with reduced ejection fraction (HFrEF, defined as ejection fraction less than or equal to 40 percent), acute coronary syndrome (based on clinical diagnosis and angiography if available), and myocarditis (based on clinician diagnosis and either cardiac MRI or troponin elevation). When a pre-specified cardiac outcome was identified, the date of onset was recorded. Differences in proportions were analyzed via Chi-squared and Fishers exact tests, and time-to-event analyses were performed via Cox Proportional Hazards Models, incorporating a false discovery rate correction for multiple outcomes. All analyses were performed using SAS v9.4. Results: 88 patients were included in the final analysis, of whom 69 (78.4 percent) were categorized as anti-Ro-52 positive. Patients with anti-Ro-52 positivity had a higher maximum recorded serum creatine kinase (median 1297 vs 395 units per liter, p = 0.042). No significant associations between anti-Ro-52 positivity and the pre-defined cardiovascular outcomes were found over median follow up time of 12.5 years. Conclusions: In a large, single-center cohort of patients with ASyS, anti-Ro-52 positivity was not associated with an increased burden of negative cardiovascular outcomes, including the onset of pulmonary hypertension. Future studies may seek to further elucidate the mechanisms underlying the pleiotropic effects of anti-Ro-52 antibodies on the cardiopulmonary system.

Objective: Clonal hyperexpansion of CD4 T cells is a characteristic feature of rheumatoid arthritis (RA). Equally large T cell clones also arise in physiological ageing or latent viral infection and adopt a replicative senescence programme - a tolerance mechanism that limits immune activation by innate-like reprogramming and proliferative arrest. We aimed to characterise the senescence programme of hyperexpanded CD4 T cell clones in RA and to define their clinical associations. Methods: Hyperexpanded T cell clones were characterised by single-cell RNA and T cell receptor profiling of peripheral T cells from RA patients and healthy donors. Flow cytometric validation was performed in two cross-sectional cohorts (n=15, n=45), paired blood and synovial fluid (n=20) or synovial tissue (n=18) sampling, and a non-interventional study of co-stimulatory blockade with abatacept (n=6). Results: Hyperexpanded CD4 T cell clones exhibited a CCR7-CD27- phenotype and accumulated in RA joints. Their frequency correlated with disease activity and their surface profile was modulated by abatacept, suggesting susceptibility to therapeutic intervention. At the molecular level, hyperexpanded clones converged on a phenotype consistent with replicative senescence, characterised by natural killer (NK) cell-reminiscent cytotoxic reprogramming, loss of co-stimulatory molecules, and reduced translational activity. However, compared with healthy donor counterparts, hyperexpanded RA CD4 T cell clones showed reduced senescence-associated cytotoxic and NK cell markers, and increased IL-7 receptor signalling, indicating attenuated senescence and preserved capacity for homeostatic proliferation. Conclusion: We propose that replicative senescence insufficiently constrains hyperexpanded clones in RA, resulting in sustained antigen reactivity in autoreactive clones and perpetuation of chronic inflammation.

Objective We developed a patient- and joint-specific explant co-culture system to model active psoriatic arthritis (PsA) and capture donor-specific tissue responses to therapeutic interventions. Methods Based on convergent joint pathology between end-stage osteoarthritis (OA) and PsA, OA cartilage-bone and synovium tissues from arthroplasty patients were exposed to synovial fluid (SF) obtained from PsA and OA patients. Histological outcomes (synovitis, proteoglycan distribution), curated gene expression, soluble mediators, and proteinase activity were assessed over 7-21-days. Model responses to dexamethasone (DEX) and the anti-tumor necrosis factor antibody adalimumab (ADA) were evaluated. Results PsA SF induced distinct inflammatory and tissue remodeling responses compared to OA SF and control conditions, including altered cartilage proteoglycan distribution, increased synovitis, and tissue-specific transcriptional changes. Multivariate analyses identified distinct osteochondral and synovial transcriptional responses to PsA SF, characterized by reduced osteochondral COL2A1 expression and increased synovial expression of inflammatory and matrix-remodeling genes, including MMP1 and CXCL8. DEX and ADA elicited donor-specific responses across histological, transcriptional, and protein readouts. Among multivariable model outputs, histologic synovitis scores emerged as the most clinically aligned parameter, demonstrating associations with baseline PsA donor disease activity, active joint counts, pain, high-sensitivity C-reactive protein (hsCRP), and radiographic scores. Synovitis score changes to DEX and ADA treatments also aligned with corresponding PsA SF donor clinical improvements to corticosteroid and TNF-modifying therapies. Conclusion This osteochondral-synovial explant co-culture model captured donor-specific inflammatory and treatment-responsive features of PsA SF-induced pathology, thereby providing a clinically relevant ex vivo platform for studying patient-specific therapeutic responses in PsA.

Background: This study aimed to elucidate B cell subset pathology in COPD, a poorly characterized area, with a focus on its similarities to and differences from classical autoimmune disorders. Methods: Single-cell RNA-sequencing (scRNA-seq) data from COPD and autoimmune diseases were obtained from the Gene Expression Omnibus (GEO) for comparative analyses of B cell subsets and functions via differentially expressed genes (DEGs), KEGG, protein-protein interaction (PPI), and cell-cell communication analyses. Serum IgG4 was measured by ELISA and correlated with clinical parameters. Peripheral blood B cells were sorted by flow cytometry for single-cell B cell receptor (BCR) sequencing. A v-Abl-Bcl2 pro-B cell line was stimulated with cigarette smoke extract (CSE) to assess abnormal development in vitro. Results: In lung tissue, IgG4 plasma cells were enriched and expressed BCR activation and inflammatory genes and TNF-NF-kB-MAPK pathways. Serum IgG4 concentrations correlated negatively with pre- and post-bronchodilator FEV1-FVC. B cells interacted with monocytes, macrophages, fibroblasts, and endothelial cells via IL-1B-IL-6, integrin, and chemokine signaling, contributing to chronic inflammation and remodeling. In peripheral blood, transitional T1 B cells were increased, accompanied by lambda-chain enrichment and increased IGLV1-47 usage, as well as enrichment of autoimmune pathways. In the bone marrow, the numbers of pre-B I cells were increased while those of small pre-B III cells were reduced, with altered expression of BCR development genes. CSE stimulation of the pro-B cell line reduced lambda expression in a concentration-dependent manner. Conclusions: The autoimmune abnormalities in COPD appear more restricted, although IgG4 antibody generation may contribute to immune-mediated lung damage.

Joint involvement is a major driver of disability in systemic sclerosis (SSc), yet its pathophysiology remains poorly understood. In the absence of specific evidence, SSc synovitis is treated by analogy with rheumatoid arthritis (RA). Here, we present the first comprehensive molecular characterization of SSc synovitis, integrating histology, single-cell RNA sequencing, and spatial multi-omics of synovial biopsies from SSc patients, RA patients, and non-inflammatory controls with in vitro validation. We show that SSc synovitis is characterized by distinct pathomechanisms from RA. Histologically, most SSc biopsies displayed a pauci-immune pathotype with sparse immune infiltrates and predominant stromal cells. At molecular level, synovial fibroblasts in SSc were characterized by a disease-specific type I interferon (IFN) response program, in contrast to the TNF-dominant profile of RA, accompanied by dysregulation of the complement cascade. This IFN program extended across multiple synovial cell types, including monocyte-derived macrophages and endothelial cells, and was spatially organized into focal myeloid niches and a diffuse stromal program. Systemically, elevated serum IFN-2a levels were associated with the presence of clinical synovitis in an independent cohort of SSc patients. We furthermore show that similar IFN-driven programs are shared between skin and synovium in SSc. Genes downregulated by IFNAR1 blockade in SSc skin were enriched in SSc synovium, supporting IFN receptor blockade as a multi-organ target therapeutic strategy. These findings reframe SSc synovitis as a less destructive, IFN-driven stromal condition distinct from RA and provide a mechanistic basis for dedicated clinical trials for joint inflammation in SSc.

Psoriasis is a chronic autoimmune skin disorder marked by IL-17-producing {gamma}{delta} T cell ({gamma}{delta}T17) and pruritus, but immunoregulatory roles of itch-inducing neurons in this context remain unclear. This study addressed whether non-peptidergic (NP) afferents bearing the Mas-related G protein-coupled receptor D (MrgprD/NP1) and MrgprA3/NP2 subsets had differential effects on psoriasiform immunopathology. Data show human NP1 and NP2 neurons basally expressed an array of pattern recognition and cytokine receptor genes, and psoriatic human skin had a profound dysregulation of neuropeptides and their receptors. In mice, imiquimod (IMQ) application reduced the density of MrgprD+ skin afferents, whereas NP1 neuron ablation exacerbated IMQ-induced disease. Strikingly, NP1 activation using either optogenetics or {beta}-alanine before IMQ exposure significantly reduced epidermal thickness, psoriatic clinical score, and {gamma}{delta}T17 cell accumulation. In stark contrast, NP2 activation increased the numbers of {gamma}{delta}T17 cells that co-expressed amphiregulin (Areg) and exacerbated IMQ-driven skin pathology. Instead, pre-emptive NP1 stimulation shifted {gamma}{delta} T cell profiles away from being IL-17 and Areg dominant to IL-13+ {gamma}{delta} T cells expressing the transcription factor GATA3 accompanied by IL-10 secretion. Importantly, IL-10 signaling blockade reversed NP1-mediated suppression of IMQ-induced dermatitis. These data show that sensory neuron subsets can distinctly modulate inflammatory skin disease.

Fibrosing skin diseases are highly morbid conditions with diverse clinical and histopathologic features. Prior work, primarily in systemic sclerosis (SSc), has yielded mixed data regarding the immune drivers of fibrosis, as well as the identity and spatial localization of pro-fibrotic fibroblast cell subsets. Here, we focus on morphea and eosinophilic fasciitis (EF), which cause more acutely inflammatory skin fibrosis. Using multimodal single-nucleus and spatial transcriptomics, we find that effector CD8+ T cells are highly enriched in fibrotic skin. These cells are particularly abundant in inflammatory tissue domains bordering fibrotic stroma, which are marked by expression of interferon-{gamma} stimulated genes. Inflammatory domains feature a loss of local homeostatic fibroblast populations and replacement with ADAM12-expressing inflammatory fibroblasts and myofibroblasts, which co-localize closely with CD8+ T cells. All subtypes of morphea featured similar patterns of CD8+ T-cell-associated fibro-inflammatory zonation and fibroblast transformation, suggesting that shared mechanisms can drive fibrosis across stromal compartments of skin. We apply these findings to a large publicly available scleroderma dataset and find that similar processes occur in SSc. Mechanistically, ablation of CD8+ T cells in mice ameliorates bleomycin-driven inflammation and fibrosis, as does fibroblast-intrinsic abrogation of IFN-{gamma} signaling. These data establish CD8+ T cell-driven fibrogenesis as a key feature of fibrosing skin diseases and raise the prospect of targeting CD8+ T cells in autoimmune fibrosis more broadly. One sentence summarySpatial profiling of morphea-spectrum diseases reveals CD8 T cells as key drivers of fibrosis through fibroblast IFN-{gamma} signaling.

BackgroundADP-ribosylation factor-like protein 15 (ARL15) is a rheumatoid arthritis (RA) susceptibility gene identified through GWAS. Previous studies suggested a role for ARL15 in synovial fibroblast (SF) pathogenicity, but its contribution to inflammatory arthritis remains unclear. We investigated the inflammatory role of ARL15 and its therapeutic potential in RA. MethodsARL15 was overexpressed in MH7A cells followed by bulk RNA sequencing and pathway enrichment analyses. Therapeutic relevance was evaluated in collagen-induced arthritis (CIA) mouse model using anti-ARL15 monoclonal antibodies, ARL15-targeting siRNA, or isoquinoline. Arthritis scores, histopathology, micro-CT and serum cytokines were assessed. Publicly available single-cell RNA sequencing (scRNA-seq) datasets were analyzed to determine ARL15 expression in RASF subsets. ResultsARL15 overexpression induced a pro-inflammatory transcriptional program characterized by upregulation of IL1A, IL1B, IL6, IL8, CXCL1, CXCL10, and CCL20. Gene set enrichment analysis revealed activation of IL6-JAK-STAT, TNF, interferon-response, and KRAS signaling pathways, with suppression of oxidative phosphorylation, lipid metabolism, and mTORC1 signaling. In CIA mice, ARL15 inhibition significantly reduced arthritis severity, inflammatory infiltrates, and joint destruction while preserving cartilage and bone integrity. Serum TNF-, IL-6, and IL-1{beta} levels were markedly decreased following ARL15 blockade. Combination monoclonal antibody treatment demonstrated the greatest therapeutic benefit. scRNA-seq analysis showed broad ARL15 expression across RA fibroblast populations, with enrichment in inflammatory lining and SF subsets. ConclusionsARL15 is a pro-inflammatory regulator of SF activation and arthritis progression. Integrated transcriptomic, single-cell, and in vivo analyses identify ARL15 as a therapeutic target for RA and support further translational development of ARL15 based therapies.

An autocrine pro-adhesive/pro-contractile signaling loop, through the mechanosensitive transcriptional cofactor YAP, promotes fibrosis. The CCN family of matricellular proteins modify adhesive signaling. Of these, CCN3 is antifibrotic. We show that BLR-200, a CCN3-derived peptide, has anti-fibrotic properties in the bleomycin-induced model of scleroderma skin fibrosis. In vitro, BLR-200 delayed, but did not abolish, fibroblast adhesion to collagen and nuclear YAP localization. In vivo, BLR-200 prevented/treated bleomycin-induced skin fibrosis, and reduced bleomycin-induced expression of profibrotic genes including alpha-smooth muscle actin, CCN1 and CCN2. Lineage tracing and scRNA-seq analyses revealed that the myofibroblasts in this model were quantitatively derived from collagen-lineage Pi16+/Col15+ve fibroblasts. BLR-200 prevented myofibroblast differentiation in this model and trajectory of fibroblasts toward a Sfrp2-positive subset, a cell type associated with poor clinical outcome. BLR-200 impairs YAP activation in vitro and appearance of translationally-relevant fibroblast subtypes in vivo and is a novel anti-fibrotic agent for SSc skin fibrosis.

The neuronal mechanisms driving progression in neuroinflammatory disorders from early relapse-remitting phases to later neurodegenerative phases remain largely elusive. Functional brain state shifts towards hyperactivity, persisting beyond relapses, represent an early maladaptive response. Here, in remission stage of an experimental autoimmune encephalitis (EAE) mouse model of RRMS, we identified a reduced excitability upon optogenetic stimulation in the brain stem, the area of active disease, while in the cortex a persistent cortical neuronal hyperactivity and synaptic remodeling emerged, accompanied with an increase of markers of early apoptosis. In contrast, hippocampal circuits, which undergo a functional state shift without hyperactivity, do not show increased apoptosis. Visual cortical networks showed a deterioration of the accuracy of encoding visual information and a decrease in the behavioural visual discrimination ability in mice. In RRMS patients in remission, we identified a reduced visual colour discrimination, indicating both the presence and the clinical relevance of early brain state maladaptation that may contribute to progression independent from relapse activity (PIRA). SummaryIn a RRMS model and in patients, impaired visual processing was reported, indicating brain state maladaptations, associated with persistent cortical hyperactivity, brain stem hypoactivity, synaptic remodeling, and apoptosis. These maladaptations might contribute to relapse-independent disease progression through sustained network dysfunction.

The IgG Fc chain carries a single N-linked glycan which may undergo changes. Increased agalactosylated N-glycans are associated with rheumatoid arthritis (RA) and regarded as pro-inflammatory. Dysregulated neutrophils can make important contributions to host tissue damage. In RA, immune complexes (ICs) that have precipitated onto synovial joint surfaces activate neutrophils via Fc receptors, promoting localised inflammation. We engineered recombinant human monoclonal IgG with agalactosylated or galactosylated N-glycans, generated immobilised ICs and stimulated healthy donor and RA patient blood-derived neutrophils, comparing reactive oxygen species (ROS) production as read-out of neutrophilic inflammation. Both healthy donor and RA patient neutrophils generated less ROS when stimulated with ICs made from agalactosylated IgG. Mechanistically this was due to poorer binding of agalactosylated ICs to neutrophil FcgammaRs, causing lower activation of Akt and p38 MAPK. Both are required for immobilised IC-mediated stimulation of the neutrophil NADPH oxidase. Taken together, this suggests that disease-associated, agalactosylated IgG does not in fact promote inflammation and host tissue injury, at least not by acting on neutrophils. We propose that rather than promoting inflammation, agalactosylated IgG N-glycans that accompany inflammatory disease may arise as part of a compensatory mechanism that is aimed at reducing excessive inflammation and host tissue injury.

Antibody-mediated rejection (AMR) is a major cause of kidney allograft failure, with donor HLA-specific antibodies (DSA) recognized as primary drivers of AMR pathology. However, a significant proportion of AMR diagnoses lack detectable DSA, thus implicating DSA-independent mechanisms. In support, we previously reported on the accumulation of autoreactive B cells in rejecting renal biopsies, which raised the possibility that autoreactive IgG produced within the allograft contributes to graft pathology. In this study, we used mouse models to show that rejecting kidney allografts preferentially promoted a breach in autoreactive B cell tolerance, leading to the local production of autoreactive antibodies. Notably, autoreactive IgG responses were uncoupled from DSA production, indicative of distinct regulation. Organoid cultures confirmed that autoantibody production was observed in the rejecting kidney, whereas DSAs were produced in both the lymph node and graft. Intrarenal B cells expressing Nur77 were enriched for autoreactivity, consistent with in situ antigen recognition. Finally, autoreactive antibodies are pathogenic, since inhibiting autoantibody production with transient anti-IL-15 and CTLA-4Ig led to preserved kidney allografts. These unique features of in situ autoantibody responses may be relevant to diverse diseases with chronic tissue inflammation beyond transplantation.

Background: Interstitial lung disease (ILD) is one of the most common and potentially most devastating extra-articular complication of rheumatoid arthritis (RA) and is associated with substantial morbidity and mortality. However, reliable tools for the early identification of ILD in patients with RA remain limited. This study aimed to identify plasma protein biomarkers of RA-ILD and develop an interpretable machine learning model for risk prediction using data from the UK Biobank. Methods: We first evaluated the association between baseline RA and the risk of incident ILD in the UK Biobank using Cox proportional hazards models. Mendelian randomization analysis was then performed to investigate the potential causal relationship between RA and ILD. Finally, we analyzed 2,920 plasma proteins measured using the Olink platform in 781 eligible RA patients. Proteins associated with ILD risk were identified using Cox proportional hazards models and subsequently used to construct eight machine learning models. Model performance was assessed using the receiver operating characteristic curve (ROC) and decision curve analysis. The best-performing model was further interpreted using Shapley additive explanations (SHAP) to evaluate feature importance. Results: Compared with participants without RA, Patients with baseline RA had a significantly higher risk of developing ILD (Hazard ratio: 4.425, 95% CI: 3.549,5.518). The MR supported a potential causal association between RA and ILD (Odds ratio: 1.227, 95% CI: 1.121,1.343). Among the eight machine learning models, the CatBoost model showed the best performance, achieving an area under the curve (AUC) of 0.884 (95% CI: 0.773,0.996). The SHAP analysis identified LAG3, NPC2, and LAMP3 are the three most important plasma protein predictors of ILD development in patients with RA. Conclusion: Plasma proteomics combined with machine learning may provide a promising approach for identifying biomarkers and predicting ILD risk in patients with RA. LAG3, NPC2, and LAMP3 may serve as candidate biomarkers for RA-ILD and warrant further validation. Keywords: Rheumatoid arthritis, Interstitial lung disease, Mendelian randomization, Machine learning, Plasma proteins.