Clinical and Experimental Immunology

Introduction: Incomplete recovery from relapses contributes to long-term disability accumulation in relapsing remitting multiple sclerosis (RRMS), yet the relationship between immune regulation and relapse recovery remains poorly defined. Objective: To longitudinally characterize regulatory/effector immune cell dynamics in untreated RRMS patients and assess their association with immune balance and relapse recovery. Methods: Monocytic myeloid-derived suppressor cells (M MDSCs), regulatory T cells (Treg), and effector CD4 T cell subsets were measured in blood from 69 untreated RRMS patients sampled during relapse or remission and reevaluated after 12 months. Associations with clinical recovery after relapse were examined. Results: During relapse, patients exhibited higher M MDSC and Treg frequencies than in remission, while effector T cell subsets remained unchanged. Over one year, M-MDSCs increased consistently regardless of baseline clinical status, whereas Treg frequencies remained stable. Effector to M MDSC ratios were markedly elevated during relapse and declined over time, while effector-to-Treg ratios showed minimal variation. M MDSC levels during relapse were associated with sustained regulatory features at 12 month follow up. Importantly, higher baseline M MDSC levels, but not Treg frequencies, were associated with complete relapse recovery at one year. Conclusion: These findings suggest that circulating M-MDSCs, but not Treg, reflect interindividual differences in immune regulation and clinical recovery after relapse in early RRMS.

Multiple sclerosis (MS), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and neuromyelitis optica spectrum disorder (NMOSD) are immune-mediated inflammatory disorders of the central nervous system (CNS). The temporal relationship between disease-specific autoantibodies and biomarkers of CNS injury before diagnosis remains unclear and is relevant for understanding early pathobiology. Here, we conducted a multicentre retrospective longitudinal case-control study using prediagnostic plasma from 362 individuals who later developed MS, 145 who developed MOGAD, and 60 who developed NMOSD. Plasma IgG levels against CNS antigens, MOG, and AQP4, as well as neurofilament light chain (pNfL), were quantified, and temporal relationships between immune activation, neuroaxonal injury, and clinical disease onset were modelled using linear mixed-effects models and survival analyses. In MS, EBNA-1-specific and CNS-cross-reactive IgG were elevated up to 77.8 months before diagnosis, preceding pNfL increases by 44.9 months. In NMOSD, AQP4-IgG seroconversion occurred 32.5 months before diagnosis and preceded pNfL elevations by 40.4 months. In MOGAD, pNfL elevations preceded MOG-IgG seroconversion by 11.2 months. Thus, in MS and NMOSD, humoral autoimmunity precedes detectable CNS injury, whereas in MOGAD, neuroaxonal injury occurs before circulating MOG-IgG. These distinct temporal patterns suggest differing early immunopathological trajectories and may provide a framework for future studies of early disease biology and biomarker-guided risk stratification.

Circulating proteins have been widely investigated as potential biomarkers in multiple sclerosis (MS), yet findings across studies are often inconsistent, likely reflecting differences in disease stage, treatment exposure, and cohort composition. Studying individuals at elevated risk of MS prior to disease onset offers a unique opportunity to identify immune alterations that precede clinical disease while minimizing confounders. Here, we investigated whether alterations in six previously MS-associated biomarkers are detectable and associate to underlying genetic susceptibility in two independent sample collections comprising people with MS (pwMS), healthy controls, and asymptomatic first-degree relatives of pwMS from the Genes & Environment in MS (GEMS) study cohort. The panel, representing complementary axes of MS immunopathology, included granzyme A (GZMA), MER tyrosine kinase (MERTK), interleukin-2 receptor alpha (IL2RA), osteopontin (SPP1), CD30 (TNFRSF8), and chitinase-3-like protein 1 (CHI3L1). None of the proteins demonstrated associations with MS. A composite score constructed from externally derived effect estimates was not associated with MS status in either collection or in meta-analysis. Among asymptomatic first-degree relatives, the composite score was not significantly associated with group status. In contrast, an inverse correlation between SPP1 and the MS genetic risk score among GEMS participants was found ({beta} = -0.246, p = 0.001). Together, these findings suggest that several circulating proteins recently proposed as MS biomarkers are not robust tools to distinguish MS from healthy individuals. However, SPP1 levels are highlighted for further evaluation among at-risk individuals, and further work is needed to determine whether circulating immune signatures can capture the earliest stages of MS in at-risk individuals.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterised by sustained type I interferon signalling and widespread immune dysregulation. Low-density neutrophils (LDNs) are expanded in SLE and display pro-inflammatory and tissue-damaging properties. However, their metabolic phenotype remains poorly defined. Here, we performed a comprehensive metabolic characterisation of circulating LDNs and normal-density neutrophils (NDNs) from patients with SLE and matched healthy individuals (HC). Neutrophil subsets were isolated from peripheral blood of SLE patients and HC donors using a two-step protocol of negative selection and Percoll density centrifugation. Immunophenotyping phenotype was carried out by flow cytometry to assess phenotypic expression of common neutrophil markers CD15, CD16, CD10, CD66b, CD62L, MPO, and IL-1{beta}. Bioenergetic profiling of LDNs and NDNs was performed in situ using the Seahorse MitoStress test to measure oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Metabolic flexibility and phenotypic alterations were assessed in LDNs and NDNs following inhibiting mitochondrial metabolism with oligomycin and glycolysis with 2DG. We found that SLE LDNs exhibit an immature phenotype compared with autologous and healthy NDNs, as determined transcriptionally by C/EBP{varepsilon} and by surface protein expression levels of CD10. Both LDNs and NDNs from SLEDAI[≥]4 patients demonstrated significantly elevated ECAR relative to HC neutrophils. Further, SLE LDNs displayed enhanced metabolic flexibility, with the capacity to switch towards a glycolytic phenotype under metabolic stress conditions. Inhibition of glycolysis altered the inflammatory and maturation-associated phenotype of both SLE neutrophil subsets, indicating a direct link between cellular metabolism and pathogenic neutrophil function. Collectively, these findings identify fundamental metabolic alterations in SLE neutrophil subsets and support neutrophil immunometabolism as a potential therapeutic target in SLE.

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.

Systemic lupus erythematosus (SLE) is associated with infection susceptibility and altered innate immune function. Monocyte metabolism is linked to appropriate cytokine release and bacterial containment. We investigated cytokine production and metabolic programming in the monocyte population from SLE patients and healthy controls following lipopolysaccharide (LPS) stimulation. SLE monocytes displayed increased IL-10, TNF, and IL-8 production, with impaired IL-1{beta} induction. Metabolic profiling revealed altered substrate use, with increased glucose dependence and reduced fatty acid and amino acid oxidation after LPS stimulation. SLE patients exhibited reduced numbers of classical monocytes, expansion of intermediate monocytes, and dysregulated subset-specific metabolic reprogramming in response to LPS. This descriptive study provides a cornerstone for (i) understanding infection susceptibility in SLE, (ii) subset-resolved immunometabolic profiling as a tool in autoimmunity, and (iii) developing future metabolic-targeted therapeutic strategies HighlightsO_LIDescriptive mapping shows SLE monocytes are proinflammatory with glucose dependence after LPS C_LIO_LIClassical and intermediate SLE subsets show divergent baseline metabolic preferences versus healthy C_LIO_LISLE subsets display aberrant LPS responses, i.e.. increased glucose and reduced fatty acid oxidation C_LIO_LIThis study provides a cornerstone for subset-resolved immunometabolism in infection susceptibility. C_LI

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.

Progressive neurodegeneration in the central nervous system (CNS) in multiple sclerosis (MS) is driven by chronic inflammatory demyelination. Neutrophils are increasingly recognized as versatile innate immune cells with potentially underappreciated roles in CNS inflammation, but their contribution to MS pathology remains poorly understood. Interestingly, we observed foamy neutrophils in active CNS lesions of MS patients. Therefore, we investigated the ability of human neutrophils to internalize myelin debris and assessed how this impacts their functional phenotype. Neutrophils exhibited efficient myelin uptake, peaking between 3 and 6 hours, predominantly through complement opsonization and internalization via complement receptor 3. Prolonged exposure to high concentrations of myelin induced a pro-inflammatory phenotype, marked by increased production of reactive oxygen species, neutrophil extracellular traps, and inflammatory mediators such as CXCL8 and CCL3. Gene expression analysis revealed a dose-dependent inflammatory signature after myelin uptake, characterized by gradual upregulation of CXCL8 and decreased ARG1 expression, suggesting a shift toward a pro-inflammatory neutrophil phenotype. These findings provide novel insights into the role of neutrophils in myelin clearance and inflammation in the CNS, highlighting complement receptor 3-mediated uptake and downstream pro-inflammatory activation as key mechanisms.

Hematopoietic stem and progenitor cells (HSPCs) sustain the production of hundreds of billions of new cells per day to maintain our blood and immune system. In this process, HSPCs regulate the hematopoietic output by sensing and integrating diverse physiological cues. Thus, HSPCs express many receptors traditionally studied for their functions in the immune system, and this allows HSPCs to directly detect microbial compounds, endogenous danger signals, cytokines, and other inflammatory mediators. However, how the expression levels of such receptors on HSPCs change under chronic inflammation and how such changes alter HSPC functions and immune cell production remains unexplored. Working in a murine model of rheumatoid arthritis, we demonstrate the induction of microbial sensors TLR2 and CD14, orphan inflammatory receptor TREM1, and checkpoint receptor PD-L1 on HSPCs and particularly the myeloid progenitor cells in the arthritis-afflicted mice. Furthermore, we demonstrate that the stimulation of HSPCs through these receptors in culture can significantly alter the dynamics of cell expansion and differentiation, with distinct responses from HSPCs of arthritis-afflicted versus healthy control mice. We hypothesize that the induction and stimulation of HSPCs through these immune receptors under chronic inflammation may impact the output and functional properties of their immune cell progeny, positing HSPCs as central players in the pathogenic inflammatory responses of rheumatoid arthritis and potentially other chronic inflammatory diseases. HIGHLIGHTSO_LIHematopoietic progenitor cells in murine models of rheumatoid arthritis show an upregulation of immune receptors TREM1, PD-L1, TLR2, and CD14. C_LIO_LIStimulation of murine hematopoietic stem and progenitor cells through these receptors in culture alters the dynamics of their expansion and differentiation. C_LIO_LIIn such cultures, hematopoietic stem and progenitor cells from mice afflicted with rheumatoid arthritis show altered responses to stimulation as compared to healthy controls. C_LI

BackgroundVedolizumab, a gut-selective anti-integrin therapy, is effective in IBD, but response rates remain variable. Conventional clinical and biochemical markers, including C-reactive protein and faecal calprotectin, have limited predictive value. Although recent transcriptomic studies have implicated T-cell-related signatures in predicting vedolizumab response, these findings lack validation across independent cohorts. MethodsWe analyzed pre-treatment transcriptomic profiles from whole blood and T-cell subsets across five independent cohorts comprising 100 patients with UC and CD. The primary outcome was clinical response. Secondary outcomes included clinical and biochemical remission. ResultsAmong the 100 patients, 61 were responders and 39 non-responders, with no significant baseline clinical differences. Gene set enrichment analyses revealed downregulation of interferon alpha and gamma signalling in responders baseline blood samples, a finding validated across independent cohorts. Downregulated interferon signalling at baseline was also observed in patients who achieved clinical and biochemical remission. To build a predictive model, an adaptive elastic net logistic regression model was applied to baseline whole-blood RNA-sequencing data. The classifier achieved an AUC of 1.0 in training, 0.71-0.83 in UC validation cohorts, and 0.64-1.0 in CD cohorts. Reduced interferon signalling was observed across CD4{square} and CD8{square} T-cell subsets, including regulatory T cells, suggesting a broad immune signature rather than cell-type specificity. ConclusionsDownregulated interferon signalling in peripheral blood prior to treatment is a reproducible molecular signature predictive of vedolizumab response and biochemical remission. Whole-blood transcriptomics revealed a robust interferon-axis signal that predicted vedolizumab response across independent cohorts, with stronger performance in UC than CD. Given heterogeneous clinical endpoints and assessment windows, these data provide proof-of-concept that warrants validation with standardised, endoscopy-based outcomes.

Background and Aims: Fatigue is a prevalent and disabling symptom in inflammatory bowel disease (IBD), yet its underlying biological mechanisms remain poorly understood. We aimed to characterize fatigue-associated molecular signatures in IBD patients by integrating DNA methylation and mRNA expression analyses. Methods: Peripheral blood was collected from 40 patients with Crohn's disease (CD), 29 with ulcerative colitis (UC), and 10 healthy controls. Fatigue severity was assessed continuously using the Multidimensional Fatigue Inventory (MFI). Epigenome-wide DNA methylation profiling and mRNA sequencing were performed, identifying differentially methylated regions (DMRs) and differentially expressed genes (DEGs) for active and quiescent CD and UC, adjusting for age, sex, and smoking status. Pathway enrichment analysis was performed on genes with differential methylation and expression. Results: In active CD, more severe fatigue was associated with transcriptional suppression of immune and metabolic pathways (246 DMRs; 1,090 DEGs), versus upregulation of mitochondrial and metabolic processes in quiescent CD (200 DMRs; 1,619 DEGs). In active UC, fatigue was associated with anabolic pathway upregulation and epigenetic silencing of neuroactive pathways (6,927 DMRs; 343 DEGs; 56 concordant genes). Quiescent UC showed transcriptional changes without significant epigenetic pathway enrichment (1,710 DMRs; 3,224 DEGs). Healthy controls exhibited a distinct profile spanning metabolic, immune, and neuronal pathways (8,621 DMRs; 395 DEGs). Fatigue-associated signatures were largely non-overlapping across all five groups. Conclusions: Fatigue-associated molecular profiles differed substantially by disease subtype and activity state, highlighting the biological heterogeneity of IBD-related fatigue and laying the foundation for multi-omics approaches to identify biomarkers and potential therapeutic targets.

BackgroundTryptophan (Trp) metabolism is a central immunometabolic axis in inflammatory bowel disease (IBD) and has been linked to inflammatory activity and immune regulation. While individual Trp metabolites have been associated with disease severity and treatment response, systems-level frameworks to define metabolic subtypes in IBD are lacking. ObjectiveTo identify reproducible Trp-related metabolic subtypes ("metabotypes") in IBD and assess their association with disease activity, clinical outcomes, and early disease development. DesignWe applied unsupervised clustering to serum concentrations of 16 Trp-related metabolites in a discovery cohort of patients with IBD undergoing biologic induction therapy (n=134). Metabotypes were validated in three independent IBD cohorts (total n>2,800), a healthy reference population, and a prospective cohort of first-degree relatives at risk for Crohns disease. Associations with disease activity, longitudinal outcomes, and metabolic pathways were assessed using multivariable regression and survival analysis. ResultsFour reproducible metabotypes with distinct metabolite profiles were identified across cohorts: Low Kyna, High Kyna, High Quin, and Balanced. Low Kyna and High Quin metabotypes were consistently associated with increased inflammatory activity and adverse clinical outcomes, including increased risk of treatment escalation and disease progression. Pathway-level analyses revealed alterations in NAD-related, lipid, and amino acid pathways between inflammatory metabotypes. A metabotype resembling inflammatory disease states was enriched in individuals who later developed Crohns disease in a prospective pre-disease cohort. ConclusionTrp-linked metabotypes define reproducible immunometabolic states in IBD that associate with disease activity and clinical outcomes and may precede disease onset. These findings provide a framework for metabolic stratification and biomarker-guided clinical trials targeting immunometabolic pathways. What is already known on this topicTryptophan metabolism through the kynurenine pathway is a central immunometabolic axis in inflammatory bowel disease (IBD) and has been linked to inflammatory activity and immune regulation. Individual tryptophan metabolites have been associated with disease severity and treatment response, but their clinical utility for patient stratification remains limited. Systems-level approaches to define clinically meaningful metabolic subtypes in IBD are lacking. What this study addsWe identify four reproducible tryptophan-related metabolic subtypes ("metabotypes") that are consistently associated with disease activity across multiple independent IBD cohorts. Inflammation-associated metabotypes show distinct pathway-level alterations, including differences in NAD-related metabolism and broader metabolic programs. A metabotype resembling inflammatory disease states is detectable before clinical diagnosis in individuals who later develop Crohns disease. How this study might affect research, practice or policyMetabotype-based classification provides a framework for molecular stratification of patients in mechanistic studies and clinical trials targeting immunometabolic pathways. This approach may support biomarker-guided monitoring of disease activity and disease progression in IBD. Identification of preclinical metabolic states highlights the potential of metabolomics for early disease detection and prevention-oriented research strategies.

Background: Serum neurofilament light chain (NfL) indexes axonal injury and glial fibrillary acidic protein (GFAP) astrocytic pathology in multiple sclerosis (MS). GFAP rises disproportionately as relapsing-remitting MS (RRMS) shifts to progressive forms on research-grade SIMOA. The commercial Roche Elecsys ECLIA platform reads six-fold lower and is undescribed across subtypes. Objective: To describe both markers by MS subtype on ECLIA. Methods: Retrospective single-center analysis of 603 MS patients (2022-2026). NfL and GFAP were measured by LabCorp Roche Elecsys ECLIA; subtype came from ICD-10 codes and notes. We examined both markers by subtype, their correlation, and NfL against gadolinium-enhancing (Gd+) MRI lesions. Results: Median NfL was 1.32 pg/mL (IQR 1.01-1.91). Both rose with stage, steeper for GFAP: NfL 1.18 (RRMS), 1.54 (SPMS, p<0.001), 1.78 (PPMS, p=0.001); GFAP 41.90, 63.80 (p<0.0001), 75.75 (p=0.08, n=6). SPMS and PPMS GFAP did not differ (p=0.83). The markers correlated moderately (r=0.569). Of 34 Gd+ encounters with NfL within 30 days, 3 (9%) were elevated. Conclusion: On ECLIA, both markers rose with MS stage, GFAP more steeply, and both progressive subtypes exceeded RRMS. NfL rarely flagged a recent Gd+ lesion, consistent with its delayed kinetics. The two index distinct processes and reproduce on an orderable assay a profile once confined to research-grade SIMOA.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common neurotoxicity of cancer treatment with limited diagnostic, monitoring, and treatment options. Neurofilament light chain (NfL) is an axonal cytoskeletal protein released during neuroaxonal injury and a promising biomarker of CIPN, but prospective evidence for NfL as a marker of CIPN from vincristine-containing lymphoma chemotherapy treatment remains limited. To fill this gap, we conducted a pragmatic single-center prospective observational cohort study of adults with non-Hodgkin lymphoma (NHL) receiving first-line vincristine-containing chemotherapy to evaluate NfL dynamics across multiple pre-cycle visits and assess 68 relationships with patient-reported and clinician-graded neuropathy measures. We followed 25 participants during 4-6 months of chemotherapy, and a small subset of those participants (n=6) for 24-42 months post-chemotherapy. Serial plasma NfL was measured and CIPN symptoms were assessed using patient- and clinician-reported measures. Longitudinal changes were analyzed using mixed-effects models. Plasma NfL increased relative to pre-cycle1 at all timepoints (all p<0.001), increasing more than threefold by pre-cycle4. Patient-reported CIPN scores and clinician-graded neuropathy also increased during treatment. Exploratory pooled visit-level analyses showed a modest NfL-CIPN association (Spearman {rho}=0.393, p=0.004), while timepoint-specific, lagged, and post hoc sensitivity analyses suggested potential to predict persistent CIPN symptoms from early NfL concentrations. To our knowledge, these findings provide the first prospective evidence that NfL is sensitive to vincristine exposure in adults with NHL and may complement patient-reported symptom assessment, clinician grading, and dose-modification context in future CIPN monitoring studies.

To understand the dysregulation of autoreactive B cells in SLE, we tracked Ro60-specific cells in seropositive (SP) and seronegative (SN) patients and healthy donors (HD), using flow cytometry and monoclonal antibodies. Consistent with permissive central tolerance, Ro60+ naive B cells were present in all groups with increased anergy in HD. HD and SN SLE also had greatly decreased or absent Ro60+ memory and ASC, which were greatly increased in active SP SLE, thereby indicating defective distal tolerance in the latter group. Notably, Ro60 autoreactivity was strictly purged from naive-derived extra-follicular B cells in HD and SN SLE, but expanded in SP SLE, suggesting the importance of autoreactivity censoring in this pathway. SLE clustering of the distribution of Ro60+ B cells identified disease heterogeneity in tolerance enforcement in SLE. Finally, we demonstrate a much higher degree of polyreactivity against other lupus antigens in SLE Ro60+ naive cells, which is greatly attenuated in memory cells. Our work represents the first systematic study of antigen-specific autoreactive B cells and ASC in SLE. It enhances our understanding of human B cell tolerance and defines new approaches to measuring autoimmune activity in the course of SLE, including the assessment of immune resetting after B cell depletion therapies.

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease driven by uncensored B and T cell autoreactivity. Understanding this pathogenic process has been hampered by lack of studies of secondary lymphoid organs in human SLE. Using minimally invasive lymph node fine needle aspirates (LN-FNAs), we profiled tissue-resident immune cells from 59 SLE patients and 34 healthy controls through high-dimensional 43-color flow cytometry, antigen-specific tetramer probing, and sc-RNA sequencing with paired VH/VL repertoire analysis. Our findings reveal hyperactive lymph node immunity in SLE characterized by spontaneous germinal center (GC) activation, plasma cell accumulation enriched in mature CD19- and CD138+ antibody-secreting cells, and increased frequencies of both GC-TFH and PD-1+CXCR5- T extra-follicular helper cells. SLE lymph nodes harbored large oligoclonal B cell families with altered isotype usage, dominated by IgG1 and IgG4. Critically, self-reactive 9G4+ and Ro60+ B cells showed defective tolerance checkpoint control, accumulating in activated naive, GC, and plasma cell compartments with distinctive PD-1+Tox+ expression absent in viral-specific responses. Single-cell repertoire analysis revealed VH4-34 clones in SLE BGC and BPC, that in contrast to HD, had not experienced clonal redemption. Instead, SLE VH4-34 clones displayed low somatic hypermutation and preserved the AVY hydrophobic patch associated with autoreactivity. Monoclonal antibody testing confirmed that unmutated AVY+ VH4-34 clones retained polyreactivity against naive B cells, apoptotic cells, and multiple self-antigens. Together, these results define "clonal damnation" as a key mechanism in SLE whereby autoreactive VH4-34 clones of pathogenic potential escape tolerance checkpoints, expand in germinal centers, and differentiate into tissue plasma cells while preserving germline-encoded self-reactivity. Combined, our study defines critical mechanisms of tolerance breakdown in lupus pathogenesis.

Background: Rheumatoid arthritis (RA) has a preclinical period characterised by elevations in serum autoantibodies. Identifying the timing and magnitude of autoantibody trajectory changes may inform screening strategies and preventative interventions. Methods: Using a Bayesian multivariate segmented regression, we jointly modelled longitudinal autoantibody trajectories from two Department of Defense Serum Repository cohorts (Sample A: 209 matched case-control pairs, 1566 samples, six biomarkers; Sample B: 309 cases with two matched controls each, 2758 samples, eight biomarkers). Change-points and magnitudes of change were estimated simultaneously under a multivariate likelihood with an unstructured residual correlation matrix. Results: In Sample A, five of six biomarkers exhibited pre-diagnostic trajectory shifts with 95% highest posterior density intervals excluding zero. RF-IgM demonstrated the earliest change-point at 8.10 years before diagnosis (95% HPDI: -10.47, -5.73), followed by ACPA-IgG at 7.43 years (95% HPDI: -9.33, -5.76). In Sample B, only the four IgG isotypes showed pre-diagnostic shifts, with anti-CCP3 (IgG) earliest at 7.00 years (95% HPDI: -8.48, -5.29). A composite metric integrating timing and magnitude reordered rankings. Conclusions: This Bayesian framework enables simultaneous estimation of change-points and magnitudes across correlated autoantibodies while fully characterising uncertainty, offering a complementary approach to prior divergence-based methods for understanding preclinical RA autoimmunity.

Background & AimsRare cases of non-hepatotropic virus (NHV) infection in humans can cause severe hepatitis and even acute liver failure. Clinically relevant animal models of NHV-induced hepatitis are limited, contributing to the incomplete understanding of pathological mechanisms. Murine norovirus (MNV) elicits hepatosplenomegaly in mice lacking the antiviral immune effector Signal Transducer and Activator of Transcription-1 (STAT1), providing a model to investigate mechanisms of NHV-induced hepatic pathology. MethodsSTAT1-sufficient and -deficient (Stat1Het, Stat1KO) littermates infected intravenously (i.v.) with MNV strain CR6 were assessed for hepatic inflammation and viral burden. Cell types and molecular pathways associated with hepatic pathology in CR6-infected Stat1KO mice were identified by flow cytometry and RNAseq of liver tissue. The relative importance of hematopoietic vs non-hematopoietic expression of STAT1 in restricting CR6 replication and maintaining tissue homeostasis was assessed in bone marrow chimeras. ResultsMNV CR6 Stat1KO mice developed severe hepatitis with patchy hepatocellular necrosis and localized enrichment of CR6-infected myeloid cells, particularly macrophages. Gene set enrichment analysis (GSEA) of hepatic biopsies isolated from CR6-infected Stat1KO mice suggested dysregulated myeloid cell activation and indicated similarities between murine and human hepatic pathologies. STAT1 expression in hematopoietic cells was protective against hepatic viral dissemination, but hematopoietic STAT1-deficiency permitted persistent hepatic MNV infection, facilitating dysregulated myeloid cell activation and hepatic fibrosis. ConclusionsThese results demonstrate that the role of STAT1 extends beyond restricting MNV dissemination and suggest that STAT1-dependent regulation of myeloid cell activation prevents acute hepatic necroinflammation and secondary fibrosis. This model of MNV-induced hepatitis may prove valuable in elucidating mechanisms of rare clinical complications. SynopsisMechanisms driving acute hepatitis caused by non-hepatotropic viruses are not well understood. We describe a model of non-hepatotropic murine norovirus infection that reliably induces liver pathology and identify a requirement for STAT1 expression in myeloid cells to promote antiviral immunity and hepatic tissue protection. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/720966v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@4ef59forg.highwire.dtl.DTLVardef@1dfac58org.highwire.dtl.DTLVardef@1abe41dorg.highwire.dtl.DTLVardef@d59e9_HPS_FORMAT_FIGEXP M_FIG C_FIG

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.

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.