Journal of Autoimmunity

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: 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.

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.

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 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.

Fibroproliferative diseases such as systemic sclerosis are complex conditions characterized by chronic skin inflammation and progressive fibrosis, with fibroblast activation as a central feature. While Transforming Growth Factor Beta (TGF-{beta}) signaling is a well-established driver of fibrosis in SSc, inflammatory pathways such as Nuclear Factor Kappa B (NF-{kappa}B) also contribute substantially to disease morbidity. We previously identified CD109 as a TGF-{beta} co-receptor and negative regulator of fibrotic signaling; however, its role in inflammatory signaling remains unknown. Here, we investigate the function of CD109 in regulating inflammatory signaling in skin fibroblasts. We show that, CD109 co-localizes and associates with Toll-like receptors (TLR2, TLR4) and tumor necrosis factor receptors (TNFRI, TNFRII), and that loss of CD109 enhances TNF--induced NF-{kappa}B activation and reprograms cytokine production in human dermal fibroblasts. Furthermore, both global and fibroblast-specific CD109 knockout mice exhibit increased immune cell infiltration and skin inflammation. In parallel, single-cell transcriptomic analyses across a pan-disease fibroblast atlas show that CD109 expression is preferentially maintained in structural and homeostatic fibroblast subtypes, whereas immune-interacting fibroblast subsets consistently display decreased CD109 levels. Pathway-level analyses of fibroblast pseudobulk samples reveal altered activity of canonical inflammatory pathways in SSc compared to healthy skin. Together, these findings identify CD109 as a fibroblast-intrinsic negative regulator of inflammatory signaling and suggest a broader role for CD109 in modulating inflammatory responses in systemic sclerosis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/736423v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@be9e08org.highwire.dtl.DTLVardef@794173org.highwire.dtl.DTLVardef@b81eb5org.highwire.dtl.DTLVardef@1e811f5_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract: CD109 Restrains Fibroblast-Driven Inflammation by Modulating NF-{kappa}B Signaling. Generated using FigureLabs.ai and edited using Adobe Photoshop. C_FIG

Systemic lupus erythematosus (SLE) is driven by pathogenic B cells. Yet, why some patients receiving B cell depletion achieve durable remission, whilst others fail remains unclear. Herewe use CD19-directed chimeric antigen receptor (CAR) T cell therapy as a mechanistic probein 18 patients with refractory SLE, with longitudinal follow-up extending up to 40 months.We show that durable, drug-free remission is defined not by the depth of B cell depletion alone,but by the elimination of the extrafollicular (EF) B cell differentiation trajectory - specifically,activated naive B cell precursors and CD11c+ T-bet+ double-negative type 2 B cells. In long-term responders, B cell reconstitution recapitulated healthy ontogeny, while the EF pathway remained truncated, coinciding with collapse of the interferon-rich milieu and contraction of PD1hi T peripheral helper cells. In contrast, in relapse, persistently elevated CXCL13, interferons and expanded PD1hi T cells preceded the B cell return, and nascent B cells immediately followed the EF differentiation trajectory in the confirmed absence of germinal centers in the lymph node, shortly followed by clinical symptoms. These findings indicate that CAR-T cell therapy achieves remission by breaking a feed-forward loop between the systemic inflammatory environment and extrafollicular B cell differentiation.

Dimeric immunoglobulin A (dIgA) is generated from IgA monomers (mIgA) via JCHAIN-dependent polymerization. DIgA is transported across epithelial barriers by the poly Ig receptor (PIGR) and confers mucosal protection, while serum contains substantial amounts of IgA monomers. Distinct plasma cell subsets have been proposed to produce either monomeric or dimeric IgA, with bone marrow plasma cells as a primary source of mIgA. Here, we addressed whether IgA plasma cell populations segregate based on mIgA or dIgA production. Flow cytometric analysis of antibody-secreting cells from bone marrow, lymphoid and mucosal tissues revealed universal intracellular JCHAIN expression across isotypes and failed to identify a discrete JCHAIN-negative IgA plasma cell population. To detect polymeric IgA, we generated a recombinant soluble PIGR that selectively bound JCHAIN-containing dIgA in Western blot, ELISA, and flow cytometry. Soluble PIGR binding was detected in all IgA plasma cells irrespective of tissue origin, arguing against a dedicated mIgA-producing plasma cell subset incapable of dIgA formation. Ex vivo cultures and single-cell DropMap secretion assays demonstrated that bone marrow and lamina propria IgA antibody-secreting cells co-secrete mIgA and dIgA. These findings suggest that dIgA assembly and secretion are general properties of IgA plasma cells and disfavor a dedicated mIgA-producing population.

Type I diabetes (T1D) is an autoimmune disorder in which the insulin producing cells of the pancreas are attacked and destroyed by autoreactive T cells. The innate immune mechanisms that contribute to T1D remain incompletely defined. Genome-wide association studies in humans have identified alleles of the IFIH1 gene, which encodes the intracellular RNA sensor MDA5, that are strongly associated with development of T1D. We previously found that MDA5 signaling drives disease and mortality in a mouse model of Aicardi-Goutieres Syndrome (AGS) caused by mutations in the ADAR1 RNA editing enzyme. Genetic dissection of disease in this ADAR1 mutant mouse model revealed that the double stranded RNA-activated kinase PKR and the RNA sensor ZBP1 are also essential for disease. To test the role of intracellular RNA detection in T1D in the nonobese diabetic (NOD) mouse model, we used CRISPR targeting to generate NOD mice targeted for Ifih1, Eif2ak2 (PKR) and Zbp1. We found that haploinsufficiency for Ifih1 resulted in modest but significant protection from T1D only in male NOD mice, but neither PKR nor ZBP1 contributed to T1D onset or incidence. Moreover, treatment of NOD mice with a pharmacological inhibitor of the integrated stress response (ISR) had no effect on T1D incidence in female NOD mice, but accelerated and exacerbated disease in male NOD mice. Together, our findings demonstrate that MDA5 and the ISR contribute to sex-specific disease incidence in NOD mice.

Thrombotic primary antiphospholipid syndrome (thrPAPS) outcomes are associated with thrombosis type (arterial versus venous), recurrence, and antiphospholipid antibody (aPL) profile (single versus triple-aPL). We investigated molecular signatures underlying disease status and high-risk phenotypes. We performed whole-blood transcriptomics and mass spectrometry-based plasma proteomics in patients with thrPAPS and age/sex-matched healthy controls. Analyses included differential expression, pathway enrichment, weighted gene co-expression network analysis (WGCNA) and machine learning. Multi-Omics Factor Analysis (MOFA2) and network propagation were applied to identify latent molecular programmes associated with high-risk phenotypes. Transcriptomic and WGCNA analyses revealed an interferon-associated module associated with high-risk phenotypes. Plasma proteomics distinguished thrPAPS from healthy controls through a coordinated thromboinflammatory signature encompassing complement, acute-phase, platelet, and coagulation-associated pathways. Complement factor D, a rate-limiting enzyme of the alternative complement pathway, discriminated recurrent from single-event thrPAPS (AUC = 0.79) and correlated with thrombotic event count (Spearman's correlation = 0.62, p < 0.001). Mixed arterial/venous phenotype showed the greatest degree of subgroup-specific dysregulation, including complement and coagulation/fibrinolysis-related proteins. MOFA2 identified a proteome-dominant latent factor that increased with aPL burden (Spearman's correlation = 0.33, p = 0.017) and was enriched for complement cascade proteins. Network propagation embedded this signature within immune-cell signalling (STAT-1, PI3K-AKT, MAPK8, SRC), N-linked glycosylation, and mitochondrial oxidative phosphorylation. Longitudinal profiling identified reactive oxygen species-associated proteins during active disease. ThrPAPS is characterised by a complement-, interferon- and platelet-driven thromboinflammatory programme that scales with aPL and thrombosis burden, converging on innate immune activation as a central feature of high-risk disease.

Age-associated inflammation varies across tissues, but whether distinct visceral adipose tissue (VAT) depots undergo inflammatory remodeling in a depot-specific manner remains unclear. Here we profiled human peri-organ VAT, comparing kidney-associated fat (KF, from kidney transplantation donors) and gallbladder-associated fat (GBF, from asymptomatic cholecystectomy patients with incidental polyps), using single-cell RNA sequencing, flow cytometry, intracellular protein profiling and in situ analysis. GBF showed broad tissue-residency and granzyme K-associated remodeling across conventional, regulatory and innate-like lymphocyte compartments, whereas KF showed stronger B cell remodeling, greater myeloid representation and more compartmentalized changes within resident effector-like CD8 T cell states. We further identified age-associated CD20 T cells with features consistent with local B-T cell interaction and an antigen-experienced, granzyme K-associated inflammatory memory phenotype. In situ analysis revealed age-associated myeloid accumulation and crown-like structure remodeling, accompanied by distinct myeloid inflammatory programs in KF and GBF. Finally, depot-specific immune signatures associated with clinical indices of adjacent kidney and liver function. These findings indicate that age-associated distinct immune programs within peri-organ VAT depots track with local tissue context and the state of the adjacent organ.

Antinuclear antibodies (ANAs) are a hallmark of connective tissue diseases (CTDs) and serve as robust diagnostic biomarkers. Because their cognate antigens are intracellular, ANAs have long been considered non-pathogenic in CTDs. Here, using systemic sclerosis (SSc) associated anti-topoisomerase I antibodies (ATAs) as a model, we provide data challenging this view. We show that ANAs enter living cells, accumulate in nuclei, and engage their intracellular antigen. Nuclear ATAs inhibit topoisomerase I enzymatic activity, induces DNA damage, fibrosis, and, through the STING pathway, activates type I interferon production. We further identify neonatal Fc receptor (FcRn)-dependent intracellular trafficking as a key determinant of ANAs nuclear access and demonstrate that pharmacological FcRn blockade impairs ATAs functionality. These findings reveal a previously unrecognized intracellular effector function of ANAs and establish a mechanistic framework by which ANAs may directly contribute to tissue injury in CTDs.

Fc receptor-like protein 5 (FCRL5) is a low-affinity IgG receptor expressed on B cells, with emerging therapeutic relevance due to its expression on multiple myeloma cells, and a potential role in regulating B cell responses. Previous reports on the FCRL5-IgG interaction vary widely in reported affinities, binding differences across IgG subclasses, and molecular requirements for maximal binding. Furthermore, the impact of Fc-engineering strategies, as used in (therapeutic) monoclonal antibodies, remains poorly understood. Here, we provide a comprehensive biochemical analysis of the FCRL5-IgG interaction. We demonstrate that FCRL5 is a true IgG Fc-receptor, binding with very low affinity (60-80 M). FCRL5 binds IgG in a manner involving primarily the two N-terminal domains of FCRL5, and the third domain for maximal binding, but with distinct essential residues in the IgG Fc-tail. Surface plasmon resonance analysis of the binding of FCRL5 to the various IgG subclasses revealed a preference for IgG1 and IgG4. Interestingly, various Fc-engineered IgG variants commonly used for silencing or enhancing of Fc receptor binding do not impact FCRL5 binding. Screening the binding of a set of IgG antibodies carrying defined sets of Fc-mutations to FCRL5 revealed E293 as a key binding determinant and led to the discovery of E293R as a mutation that selectively abrogates FCRL5 binding while preserving binding to other classical Fc{gamma}Rs. Lastly, we show that FCRL5 has considerable preference for binding afucosylated IgG. Together, our results define the essential characteristics of the IgG-FCRL5 interaction and demonstrate the potential of both naturally occurring IgG variants as well as therapeutically explored bioengineered IgG formats to differentially engage FCRL5.

Inflammatory bowel disease (IBD) arises from dysregulated crosstalk between innate immune, adaptive immune, and stromal compartments, yet the compartment-specific mechanisms driving tissue injury and tumorigenesis remain incompletely defined. To address this gap, we used conditional knockout and overexpression mouse models together with human IBD biopsy analysis to dissect the compartment-specific roles of lamin A/C in intestinal inflammation and colitis-associated tumorigenesis. Pan-hematopoietic lamin A/C deletion attenuated acute dextran sulfate sodium (DSS)-induced colitis. Myeloid-specific lamin A/C deletion ameliorated chronic colitis and was associated with altered dendritic cell (DC) programs, enhanced regulatory T cell (Treg) responses, and reduced effector T cell activation. Adoptive transfer of lamin A/C-deficient bone marrow-derived DCs recapitulated this reduced-damage phenotype in DSS colitis, while proteomic profiling revealed reduced antigen-processing and inflammatory programs together with enhanced metabolic and mucosal defense pathways. T cell-specific lamin A/C deletion reduced the Th1/Treg ratio and limited tumor development by suppressing chronic inflammation, whereas T cell-specific lamin A/C overexpression promoted severe Th1-skewed pathology, sustained intestinal inflammation, and increased colitis-associated tumor burden. Stromal fibroblast-specific lamin A/C deletion generated a tissue-protective niche characterized by enhanced epithelial barrier gene expression, regulatory cytokine production, and remodeling of the local immune milieu. Human IBD biopsies revealed compartment-specific lamin A/C alterations consistent with the murine findings. In lamina propria CD3+; T cells, lamin A/C levels were blunted in IBD and associated with local histological severity rather than IBD diagnosis, whereas epithelial lamin A/C showed a steeper crypt-axis spatial gradient in a Crohn's disease-specific pattern. Together, these findings identify lamin A/C as a cell-type- and context-dependent regulator of intestinal inflammation and tumorigenesis.

Advanced BRAF-mutant cutaneous melanoma can be treated with targeted therapy when immune checkpoint inhibitors (ICIs) fail or are not a feasible option. Nevertheless, most patients do not achieve a durable response, highlighting the critical need for therapeutic partners that enhance the long-term efficacy of targeted therapy. Transcriptomic analysis of a BRAF-mutant melanoma model of acquired resistance identified P-selectin glycoprotein ligand-1 (PSGL-1) as a top-upregulated immune mediator upon resistance acquisition. PSGL-1 is a key regulator of CD8+ T cell exhaustion and differentiation, and its inhibition has been shown to enhance T cell function across multiple disease models. Based on these observations, we hypothesized that combined targeting of BRAF/MEK and PSGL-1 would improve anti-tumor responses. Here, we demonstrate that dual inhibition of BRAF/MEK and PSGL-1 elicits durable tumor control in a preclinical model of PD-1-refractory cutaneous melanoma. Single-cell RNA sequencing of the tumor microenvironment reveals robust reprogramming of intratumoral CD8+ T cells toward a less terminally differentiated, memory-like phenotype following combined BRAF/MEK and PSGL-1 targeting. Consistent with these findings, CD8+ T cells in the tumor-draining lymph nodes of PSGL-1-/- mice exhibit enhanced functionality and a less differentiated state of exhaustion when compared with wild-type mice. To extend these observations to a translationally relevant setting, we further show that antibody-mediated blockade of PSGL-1, in combination with BRAF/MEK inhibition, yields superior anti-tumor activity compared with either monotherapy. Collectively, these findings identify PSGL-1 as a promising therapeutic target to enhance the durability of targeted therapy and provide a strong rationale for future clinical evaluation.

Introduction Complement and coagulation are tightly interconnected systems that contribute to immunothrombosis and can drive inflammatory or thrombotic diseases. Leveraging this relationship and crosstalk we developed a method to functionally evaluate complement-induced coagulation activity using thromboelastometry (thermoelastometry of complement-driven immunothrombosis; TCDI). Methods To study the complement-dependent activation of coagulation, platelet-poor plasma (PPP) from patients was mixed with healthy blood in the presence or absence of the compstatin-based C3 inhibitor Cp40. PPP from healthy controls (n=10), or from patients with antiphospholipid syndrome (APS; n=6), severe COVID-19 (n=13), rheumatoid arthritis (RA; n=7), or synovial fluid (SF) from RA patients, were analyzed for their capacity to induce complement activation in healthy blood. Whole blood coagulation was analyzed by thromboelastometry and complement-driven immunothrombosis was quantified as clotting time (CT) prolongation following Cp40 treatment, expressed as fractional difference percentage (FD%). In parallel, C3a generation was measured by ELISA to monitor the C3 inhibitory activity of Cp40. Results Plasma from patients with APS and COVID-19 induced significant CT prolongation following C3 inhibition by Cp40 and increased FD% values compared with controls, indicating active complement-driven immunothrombosis. Higher TCDI levels were associated with mortality in severe COVID-19. In RA, TCDI positivity was detected in synovial fluid (SF) rather than peripheral plasma. Moreover, TCDI-positive samples treated with Cp40 exhibited significant inhibition of C3a generation, which strongly correlated with FD% values (r=0.67, p=0.0005). Conclusion The TCDI assay may provide a rapid, real-time evaluation of immunothrombotic activity in inflammatory and thrombotic disorders, which could inform timely medical prevention.

We showed before that the endogenous peptide Nociceptin blocks the premature differentiation of oligodendrocytes (OLGs), preventing untimely precocious myelination in the developing brain. Consistent with this early function, Nociceptin brain expression is developmentally regulated, sharply decreasing with the initiation and progression of myelination. However, we now found that at difference with controls and relapsing-remitting multiple sclerosis (RRMS), Nociceptin levels are highly elevated in cerebrospinal fluid from patients with the most severe progressive MS (PMS) forms. This questioned whether Nociceptin early developmental effects could be latter recapitulated, interfering with remyelination in PMS. This possibility was tested by inducing experimental autoimmune encephalomyelitis in older mice, at an age equivalent to that with increased risk of RRMS transition into PMS. Older animals develop persistently highly debilitating clinical symptoms, and display both brain and spinal cord demyelination. Importantly, these mice exhibit elevated brain Nociceptin levels, and their treatment with an antagonist of the Nociceptin receptor (NOR) elicits a regression of clinical scoring that is accompanied by higher ratios of OLGs/OLG progenitor cells, increased myelination, and reduction of reactive astrocytes. These findings suggest that Nociceptin may be a crucial player in the age-related progression of MS; interfering with OLG maturation and remyelination, and perhaps further exacerbating neurological dysfunction by targeting astrocyte populations. The upregulation of Nociceptin secretion by human astrocytes in response to proinflammatory cytokines, also points to this peptide as a mediator of microglia-astrocyte interactions supporting MS progression with aging. NOR may offer a novel pharmacological target for ameliorating the devastating effects of MS progression.

Extrahepatic delivery of lipid nanoparticles (LNPs) to non-phagocytic cells is a major challenge, with the leading strategy involving surface functionalization with target-specific monoclonal antibody (mAb) ligands. We investigate the stability of mAb-conjugated LNPs using two anchoring systems: the commonly used DSPE-PEG2kDa-maleimide and a block copolymer, PCL5kDa-b-PEG2kDa -maleimide, with the hypothesis that conjugation to a 150,000 Da antibody could overwhelm the relatively small ~600 Da aliphatic anchor on the PEG-lipid in vivo. Shedding of the mAB would compromise targeting. Conjugation integrity following IV injection was assessed by tagging LNPs and mAbs with metal ion tracers that could be quantified by ICP-MS. Results show that DSPE-PEG-mAb rapidly (within 1h) dissociates from LNPs in blood, leading to accelerated LNP clearance. In contrast, mAbs conjugated using PCL-b-PEG remained stably associated with the LNP over the 24h circulation and clearance of the construct. Results are connected to a thermodynamic model that reproduces experimental findings for PEG-anchor(-mAb) shedding in vitro and in vivo. This study identifies anchoring strength as a critical, unconsidered parameter for in vivo performance when conjugating mAbs to LNPs for extrahepatic delivery.