Clinical and Experimental Immunology

Rationale: Sepsis is a life-threatening syndrome causing significant morbidity and mortality especially in the aging population. Clonal hematopoiesis of indeterminate potential (CHIP) is an age-related condition of clonal expansion of hematopoietic stem cells harboring somatic mutations associated with increased incidence of chronic illness and all-cause mortality. Objective: Evaluate the association of pre-illness CHIP with mortality and morbidity in patients admitted to the ICU with sepsis. Methods: We performed a retrospective study using a de-identified electronic health record linked with a DNA biorepository. We identified adult patients with sepsis who had DNA collected prior to ICU admission. We tested the association between CHIP status, determined from whole-genome sequencing, and ICU mortality, organ support-free days, and long-term survival adjusting for age, sex, race and Sequential Organ Failure Assessment (SOFA) score on ICU admission. Measurements and Main Results: Pre-illness CHIP was associated with increased sepsis mortality (OR = 1.54, 95% CI 1.13 to 2.07, P = 0.005) and fewer days alive and free of organ support (-1.7 days, 95% CI -3.2 to -0.2, P = 0.028) after adjusting for age, sex, race, and SOFA score. In sepsis survivors, CHIP was also associated with increased long-term mortality after discharge (HR 1.40, 95% CI 1.01 to 1.93, P = 0.041). Conclusions: Pre-illness CHIP was independently associated with increased mortality and morbidity in critically-ill adults with sepsis. These findings suggest that CHIP is a risk factor for sepsis severity. Elucidating the mechanism underlying this association could uncover new therapeutic interventions for sepsis.

Red blood cell (RBC) alloimmunization is a clinically significant complication in transfused patients whose immunological determinants remain incompletely understood. Type I interferon (IFN-I) signaling drives RBC alloimmunization in murine models, and systemic lupus erythematosus (SLE) is characterized by constitutive IFN-I hyperactivation alongside elevated alloimmunization rates. We analyzed three publicly available SLE RNA-seq cohorts (GSE72509, GSE112087, GSE122459; whole blood and PBMC; total n = 150 SLE) in a pre-specified discovery-replication-validation design. A 14-gene IFN-I signature score was computed per sample; differential expression, gene set enrichment analysis, and Spearman correlation were performed independently per cohort. IFN-I scores were significantly elevated in SLE versus healthy controls in all three cohorts (p < 0.01 each). IFN-high SLE patients showed 665 differentially expressed genes, with enrichment of alloimmunization-associated and plasmablast differentiation gene sets confirmed by GSEA. The alloimmunization signature score correlated significantly with IFN-I score across all three independent cohorts ({rho} = +0.77, +0.51, +0.60; all FDR q < 0.05); Tfh differentiation showed no association in any cohort. To our knowledge, this represents the first human transcriptomic evidence that IFN-I pathway activity in SLE is coupled to alloimmunization-associated immune programs in vivo. These findings identify IFN-I score as a candidate biomarker of alloimmunization susceptibility in SLE and provide translational rationale for prospective studies incorporating transfusion outcome data.

Severe forms of inflammation-induced acute and chronic myocarditis have a poor prognosis. Promising therapeutic efforts focused on monoclonal antibodies (mAbs) inhibiting inflammation-inducing molecules. However, most mAbs target only one or a limited number of such molecules. Since inflammation involves multiple redundant pathways, we postulated that an mAb inhibiting multiple inflammatory pathways would be a potent therapeutic agent. We initially tested the commercially available anti-natural killer (NK) cell mAb (anti-NK1.1), which binds a receptor expressed on NK cells and depletes them. Since NK cells are key cellular orchestrators of inflammation, by reducing their number, we aimed to inhibit multiple inflammatory pathways. Our initial studies demonstrated that administration of this antibody significantly improved myocardial outcomes in mouse models of acute myocardial infarction and of heart failure. Since NK1.1 is not expressed in human cells, we built on these promising preclinical results by developing a novel mAb targeting CD160 on human NK cells for evaluation as an immunosuppressive therapy. We found that the anti-CD160 mAb depletes both murine and human NK cells. We also found that, while CD160+ cells were largely present in the NK population, they also occurred among CD8+ and {gamma}/{delta} T cell subsets in human cells. Anti-CD160 therapy entirely prevented the deterioration of the myocardial function of mice with autoimmune-induced acute myocarditis. This outcome suggests our novel approach for inhibiting multiple inflammatory pathways may provide a potent strategy for improving outcomes of inflammation-driven myocarditis, as well as of other inflammation-driven diseases. Key PointsO_ST_ABSQuestionC_ST_ABSCan the depletion of CD160+ cells prevent autoimmune-induced myocarditis? FindingsIn this study we found that CD160 is expressed by mouse and human natural killer cells and other subtypes of cytotoxic T cells, and that a monoclonal antibody targeting CD160 depletes NK cells. In a preclinical model of experimental autoimmune myocarditis, administration of the anti-CD160 monoclonal antibody prevented myocardial dysfunction and systemic inflammation. MeaningOur results are compatible with the hypothesis that early autoimmune-induced myocardial dysfunction is promoted by CD160+ cells, which elevate inflammation-induced circulating factors (or factors released by tissue-resident cytotoxic immune cells) that cause myocardial dysfunction in the absence of myocardial necrosis or fibrosis, and further, that targeting CD160+cells with a mAb that depletes NK cells (and probably CD160 expressing cytotoxic T cells) entirely prevents the deterioration of myocardial function in such mice. This outcome suggests our novel approach for inhibiting multiple inflammatory pathways may provide a potent strategy for improving outcomes of inflammation-driven myocarditis, as well as of other inflammation-driven diseases.

ObjectivesPatients with Systemic lupus erythematosus (SLE) who carry a high genetic burden often experience more severe disease. To understand the molecular consequences of polygenic risk, we analyzed single-cell gene expression profiles in SLE patients stratified by genetic risk. MethodsSingle-cell RNA sequencing (scRNA-seq) was performed on fresh peripheral blood mononuclear cells (PBMCs) from 16 female SLE patients, stratified by a weighted polygenic risk score (PRS), and 6 healthy controls (HCs). All patients were in low disease activity (LLDAS) and treated with antimalarials only. We assessed differential gene expression, interferon (IFN) signatures, transcription factor (TF) activity, and pathway enrichment across groups. ResultsPatients with High-PRS had significantly elevated IFN scores compared to HCs (p<0.001), whereas no significant difference was observed between Low-PRS patients and HCs (p>0.05) This pattern held across multiple immune cell types, including T cells, NK cells, and monocytes. Notable genes with increased expression in High-PRS patients included ISG15 and USP18 in plasmacytoid dendritic cells (pDCs), and IFI27 and RSAD2 in monocytes. IFN-related pathways were enriched in pDCs and monocytes in High-PRS patients, and only in monocytes in Low-PRS patients. TF analysis identified IRF7 and BATF3 as key candidate regulators in High-PRS of both cell types. ConclusionsHigh polygenic risk in SLE is associated with persistent activation of IFN signaling pathways, indicating that antimalarial treatment alone is insufficient to fully suppress IFN activity, even during remission or low disease activity.

ObjectivesThe aetiopathogenesis of SLE encompasses genetic, environmental and epigenetic factors. We investigated associations between an SLE methylation risk score (MRS), HLA-DRB1*03:01, a non-HLA polygenic risk score (PRS) and clinical and immunological phenotypes. MethodsDNA methylation in whole blood from patients fulfilling [&ge;]4 ACR-82 criteria and controls were investigated using the Illumina HM450K array. The discovery cohort included 311 patients and 400 controls, and the replication cohort comprised 175 patients and 187 controls. Seventeen independent, top differentially methylated CpG sites ({Delta}{beta} of [&ge;]0.1) from case-control comparisons, were used to calculate the MRS. Genotyping was performed using the Immunochip, and the PRS included 57 non-HLA SLE SNVs. Clinical data were collected from patient charts, and serum IFN-2 was measured using Simoa. ResultsHigher MRS was strongly associated with serum IFN-2 levels (p=1.04x10-14). In both cohorts, higher MRS associated with discoid lupus, immunologic involvement, and anti-SSA/SSB/RNP/Sm autoantibodies (all p<0.05), and with higher disease activity in the discovery cohort (p=1.50x10-). MRS was also elevated in patients with multiple autoantibodies (p<1.0x10-15) and in HLA-DRB1*03:01 carriers (p<1.0x10-3). In contrast, higher PRS was associated with nephritis, anti-dsDNA positivity, and lower prevalence of anti-SSB antibodies (all p<0.05). No correlation was observed between the MRS and the PRS (p=0.35). ConclusionThe MRS defines an interferon-high, HLA-DRB1*03:01-linked SLE subset with multiple autoantibodies, partly distinct from PRS-associated nephritis risk, highlighting potentially divergent pathogenic pathways. These findings underscore the value of integrating genetic and epigenetic data to better understand underlying disease mechanisms in SLE. Key MessagesO_LIHigher MRS, but not PRS, correlated with increased levels of serum IFN-. C_LIO_LIThe MRS was associated with discoid rash, hematologic disorder, hypocomplementemia, antibodies including anti-SSA and HLA-DRB1*03:01. C_LIO_LIHigher PRS was linked to nephritis and anti-dsDNA positivity, and did not associate with the MRS. C_LI

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID are complex chronic conditions that often follow infectious triggers with overlapping clinical features but poorly defined pathophysiological relationships. This study aimed to identify disease-specific immune signatures through multiparameter immunophenotyping of monocytes, dendritic cells, and T-cell subsets. A total of 207 participants were included (ME/CFS: n = 103; long COVID: n = 63; healthy controls: n = 41). Peripheral blood mononuclear cells were analyzed using multiparameter flow cytometry. Statistical analyses included non-parametric testing, age-adjusted ANCOVA, correlation network analysis, and principal component analysis (PCA). Long COVID was characterized by increased M2-like monocyte polarization, elevated CD80 expression across monocyte subsets, expansion of dendritic cells, and reduced expression of activation markers, indicating persistent immune activation with features of immune exhaustion. In contrast, ME/CFS exhibited reduced costimulatory molecule expression, impaired CCR7-mediated immune cell trafficking, and less coordinated activation patterns, consistent with a state of immune suppression. Correlation network analysis revealed more extensive and integrated immune interactions in long COVID, while PCA identified distinct immunophenotypic components and enabled moderate discrimination between the two conditions. These findings demonstrate that ME/CFS and long COVID are characterized by distinct immune profiles, supporting the concept of divergent immunopathological mechanisms. The identified signatures may contribute to biomarker development and guide targeted therapeutic approaches.

ObjectiveTo define cellular and molecular mechanisms distinguishing active systemic lupus erythematosus (SLE) from remission by profiling autoreactive antinuclear antigen- positive (ANA+) and non-autoreactive B cells subsets in three cohorts: active disease (SLE-A), long-term, drug free remission (SLE-R), and healthy controls (HC). MethodsPeripheral blood B cells were phenotyped by flow cytometry, including ANA reactivity. Single-cell RNA sequencing (scRNA-seq) was performed on sorted ANA+ and ANA- subsets. ResultsSeven transcriptomic B cell clusters were resolved: quiescent (Naive 1, Marginal Zone B cells [MZB], IgG Memory 1) and activated (Age-Associated B cells [ABCs], Naive 2, IgM Memory, IgG Memory 2). SLE-A showed expansion of activated clusters, MZB contraction, and a higher IgG:IgM B cell ratio. SLE-R exhibited an "immunological reset," distinct from healthy homeostasis, with reduced ABCs and IgG Memory 2, persistence of Naive 2, and partial restoration of MZB and Naive 1. Interferon- (IFNa) signaling was elevated across clusters in SLE-A (SLE-A > SLE-R > HC), whereas TNF signaling was enriched in activated clusters across cohorts, with minimal differences between SLE-R and SLE-A. IFNa and TNF scores were inversely correlated. B cells predominantly expressed TNFR2, suggesting immunomodulatory TNF effects in remission. ANA+ cells in HC and SLE-R showed enriched Fc{gamma}RIIb inhibitory and IL-4/STAT6 signaling, suggesting reinstated regulatory control. DiscussionCompared to SLE-A, SLE-R was characterized by partial reversion to HC homeostasis with residual activation. These findings delineate immunologic features of remission and suggest therapeutic opportunities, including modulation of TNFR2, Fc{gamma}RIIb, and IL-4 to help sustain remission. What is already known on this topicSome patients with SLE achieve complete clinical remission without treatment, referred as immune reset; the mechanisms that underlie this state have not been well characterized. Healthy individuals and patients with Systemic Lupus Erythematosus (SLE) normally harbor similar frequencies of autoreactive B cells; the checkpoints that regulate activation of these cells are not fully defined. What this study addsB cells, stratified by their reactivity to nuclear antigens (ANA), from active SLE (SLE-A), drug-free remission (SLE-R), and healthy controls (HC) were analyzed using single cell sequencing and flow cytometry. We identified B cells states associated with disease activity; SLE-R displayed a distinct profile that differed from SLE-A and HC. TNF signaling was present in activated B cell subsets in SLE-A and SLE-R. This persistence in SLE-R may reflect an immunomodulatory function of TNF on TNFR2, which is expressed on B cells. ANA+ cells in SLE-R and HC were enriched for inhibitory Fc{gamma}RIIb and IL-4/STAT6 programs. How this study might affect research, practice or policyThe signatures identified help define the "immunological reset" state in patients with SLE-R. We also identified pathways, such as type I IFN, TNFR2, Fc{gamma}RIIb, IL-4/STAT6 as potential targets for maintaining remission.

Purpose: Aicardi-Goutieres syndrome (AGS) is a type I interferonopathy presently associated with nine genes. PTPN1 is a negative regulator of the interferon pathway previously associated with chronic inflammation and recently type 1 IFN autoinflammation. Methods: Genomic data from undiagnosed individuals with suspected AGS were interrogated for PTPN1 variants, and predicted loss-of-function (pLOF) and damaging missense variants in PTPN1 were sought in two additional academic databases as well as the All of Us database. Results: We identified 13 cases with ultra-rare heterozygous pLOF or highly damaging missense variants in PTPN1. Nine cases were identified in a cohort of 53 individuals (~ 17%) with clinical, imaging and persistent biochemical features of AGS. Median age of onset is 1.75 years (IQR 0.67), significantly later (p< 0.0001) than other AGS genotypes. Four additional cases were identified in academic datasets with variable clinical features suggestive of autoinflammation. Additionally, 49 individuals with ultra-rare, damaging PTPN1 variants were identified in the All of Us database, none had features suggestive of AGS, but autoimmunity was highly prevalent (~21.6%). Conclusion: Our data implicate PTPN1 as a cause of later-onset presentations of AGS within a broader spectrum of autoinflammatory phenotypes. Segregation and biobank data demonstrate reduced penetrance, with carriers being enriched for autoimmune disorders.

BackgroundSepsis is a major public health challenge, and reliable biomarkers are essential for distinguishing sepsis from other conditions. Neutrophil Gelatinase-Associated Lipocalin (Neutrophil gelatinase-associated lipocalin (NGAL)) has shown promise as a diagnostic marker due to its role in the immune response. This study evaluates plasma NGAL as a diagnostic tool at the time of ICU admission. MethodsWe analysed plasma NGAL and C-reactive protein (CRP) levels in 4732 adult patients admitted to four ICUs between 2015 and 2018. All patients were retrospectively screened for Sepsis-3 criteria at ICU admission. The discriminative performance of NGAL and CRP for sepsis was assessed using receiver operating characteristic (ROC) analysis, with NGAL levels adjusted for Chronic kidney disease (CKD) and age. Patients were stratified by renal function. ResultsPlasma NGAL levels were significantly higher in septic patients (p<0.001). For the whole cohort, NGAL alone yielded an Area under the curve (AUC) of 0.67 (Confidence interval (CI) 0.66-0.69), CRP yielded an AUC of 0.72 (CI 0.71-0.73, p<0.001), and combining NGAL with CRP nominally improved discriminative performance (AUC 0.74 vs 0.72, p<0.001). Stratified analyses indicated that NGAL, together with CRP, significantly outperformed CRP alone in patients with no kidney injury and those with Acute Kidney Injury (AKI) only. In contrast, differences were not significant in patients with CKD only or CKD and AKI. ConclusionIn this large cohort, NGAL showed modest discrimination for sepsis, with a nominal improvement when combined with CRP. These findings do not indicate that NGAL meaningfully improves sepsis diagnosis in the ICU.

Antiphospholipid syndrome (APS) and systemic sclerosis (SSc) are immune-mediated multisystem autoimmune diseases with distinct clinical phenotypes but overlapping pathogenic themes, including immune dysregulation, chronic inflammation, and endothelial injury. Using peripheral blood transcriptome datasets from the Gene Expression Omnibus (GSE102215: 9 APS/9 controls; GSE231691: 49 SSc/18 controls), we performed differential expression analysis within each cohort (limma; |log2FC|>1, P<0.05) and identified 281 genes dysregulated in the same direction in both diseases (100 upregulated and 181 downregulated). Enrichment analyses highlighted interferon-related and cytokine/inflammatory signaling programs in APS and SSc. To derive a compact diagnostic signature, we combined random forest feature ranking with a single-hidden-layer artificial neural network, prioritizing five shared candidate biomarkers (S100A8, IER5L-AS1, LTK, PRR5-ARHGAP8, and PCDH1). Each gene showed consistent case-control differences in both cohorts (P<0.001) and achieved good discrimination (AUC>0.75), with S100A8 performing most consistently (AUC=0.98 in APS; AUC=0.88 in SSc). CIBERSORT deconvolution indicated a myeloid-skewed blood profile in both diseases, characterized by higher neutrophil and monocyte/macrophage signals; SSc additionally showed stronger inferred CD4+ T cell and NK cell signals. S100A8 expression correlated with inferred neutrophil abundance in both cohorts (APS r=0.62; SSc r=0.58; P<0.05). Finally, miRNA-target prediction and DSigDB drug-signature enrichment generated regulatory and pharmacologic hypotheses, including immune-regulatory miRNAs (e.g., miR-155 and miR-146a) and candidate compounds (celecoxib, tamibarotene, HMN-176, and XMD14-99). Overall, these results nominate shared blood transcriptional markers and immune correlates across APS and SSc for follow-up validation.

Background and AimMASLD affects 30-38% of Indian adults, yet the contribution of genetic risk variants to disease susceptibility and fibrosis progression remains poorly characterised. We investigated the association of 12 candidate SNPs with MASLD susceptibility and fibrosis severity in North Indian patients, benchmarking allele frequencies against IndiGenomes and global populations. MethodsSixty-nine MASLD patients (75.4% male; median BMI 29.8 kg/m{superscript 2}) from a tertiary care liver clinic in New Delhi were genotyped for 12 SNPs using Illumina custom BeadChip array and Sanger sequencing. Patients were stratified by liver stiffness measurement (LSM): significant fibrosis ([&ge;]8 kPa, n=38) versus no significant fibrosis (<8 kPa, n=31). Allele frequencies were compared with IndiGenomes ([~]1,020 Indian individuals) and 1000 Genomes populations. ResultsPNPLA3 rs738409 G allele was the strongest within-cohort predictor of significant fibrosis (allelic OR 2.89, 95% CI 1.35-6.19, P=0.006; dominant model OR 3.94, P=0.008), with carriers demonstrating higher LSM (median 15.6 vs. 7.5 kPa, P=0.005). SAMM50 rs3761472 (OR 2.12, P=0.065) and FTO rs9939609 (OR 2.08, P=0.089) showed non-significant trends. In the population-level comparison, APOC3 rs2854116 T allele was the only variant significantly enriched after Bonferroni correction (64.0% vs. 47.9%; OR 1.93, 95% CI 1.35-2.77, P<0.001), followed by PNPLA3 (33.3% vs. 24.1%, OR 1.57, P=0.019) and SAMM50 (31.2% vs. 22.6%, OR 1.55, P=0.028). Notably, APOC3 showed no association with fibrosis (OR 0.96, P=1.000), suggesting a role in susceptibility rather than progression. All SNPs were in Hardy-Weinberg equilibrium. ConclusionsThis study reveals a dissociation between genetic determinants of MASLD susceptibility and fibrosis progression in North Indian patients. APOC3 rs2854116 predisposes to MASLD at the population level, while PNPLA3 rs738409 drives fibrosis severity within established disease, underscoring the need for ancestry-specific genetic risk stratification. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/26347059v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@a07808org.highwire.dtl.DTLVardef@12882adorg.highwire.dtl.DTLVardef@9b33a1org.highwire.dtl.DTLVardef@15aa5e8_HPS_FORMAT_FIGEXP M_FIG C_FIG

Background and Aims: Alterations in immunoglobulin G (IgG) N-glycosylation are implicated in inflammatory bowel disease (IBD); however, the robustness of IgG glycan signatures across IBD cohorts with diverse demographics and geographic origins remains underexplored. We aimed to determine whether compositional data analysis (CoDA) and machine learning (ML) can identify IBD-related IgG N-glycan signatures and whether these signatures capture disease-associated acceleration of biological aging. Methods: We analyzed the IgG glycome profiles of 1,367 plasma samples collected from healthy controls (HC), symptomatic controls (SC), and people with newly diagnosed Crohn's (CD), and ulcerative colitis (UC) across four cohorts (UK, Italy, United States, and Netherlands). IgG glycosylation was analyzed by ultra-high-performance liquid chromatography, yielding 24 total-area-normalized glycan peaks (GPs). Analyses were performed using cross-sectional data obtained at baseline. CoDA-powered association analyses were used to identify disease-related effects on GPs while controlling for demographic covariates. ML models were trained and evaluated to assess generalizability to unseen cohorts and demographic subgroups, with a focus on discrimination and reliability. Results: Across all cohorts, people with IBD demonstrated accelerated biological aging as quantified by the GlycanAge index. This was accompanied by consistent reductions in IgG galactosylation, with effects partially modulated by age. Classification models trained on glycomics and demographics achieved robust discrimination (AUROC~0.80) between non-IBD (HC+SC) and IBD across cohorts. Conclusion: These findings reveal accelerated biological aging in people with IBD and support the translational potential of IgG glycans as biomarkers and a novel route toward clinically interpretable personalized risk estimates.

PurposeSepsis-associated immunothrombosis significantly contributes to high mortality, yet the role of N-glycosylation in this process remains poorly understood. This study aimed to comprehensively profile the plasma N-glycosylation landscape in sepsis and elucidate how its specific reprogramming in the complement and coagulation cascades influences immunothrombotic balance and patient outcomes. MethodsWe performed in-depth 4D-DIA proteomic and N-glycomic analyses on plasma from 43 sepsis patients and 9 healthy controls. Differential expression, weighted gene co-expression network analysis (WGCNA), and protein-glycosylation correlation analyses were used to characterize molecular features. Clinical relevance was assessed via correlation and survival analyses. ResultsExtensive N-glycosylation reprogramming was observed in sepsis plasma,with marked enrichment in complement and coagulation pathways(KEGG p=7.76x10- {superscript 2}{superscript 1}).Pro-coagulant proteins(eg,vWF,fibrinogen)showed increased abundance together with enhanced site-specific glycosylation,potentially amplifying their activity.In contrast,key anticoagulant proteins(eg,SERPINC1)displayed unchanged glycosylation at critical sites despite abundance changes,which may impair function.Survival analysis revealed distinct prognostic values of glycoproteins and specific glycosylation sites.For instance,high vWF protein levels predicted mortality(HR=2.83),whereas elevated glycosylation at vWF N211 was associated with improved survival(HR=0.135),suggesting a negative regulatory role.These glycosylation markers correlated closely with disease severity and prognosis,representing potential early-warning biomarkers independent of current clinical coagulation indicators. ConclusionOur study demonstrates widespread reprogramming of the plasma proteome and N-glycome in sepsis.We propose that decoupling of protein function from abundance through N-glycosylation in the complement-coagulation network contributes to immunothrombotic imbalance.Specific N-glycosylation sites may serve as novel prognostic biomarkers,offering new perspectives for early risk stratification and glycosylation-targeted therapies in sepsis. Key PointsO_LISepsis plasma exhibits specific N-glycosylation reprogramming overwhelmingly focused on the complement and coagulation cascade. C_LIO_LIA dominant "glycosylation-dominated co-upregulation" mode in procoagulant factors, coupled with a "silent" glycosylation state in key anticoagulants, drives prothrombotic imbalance. C_LIO_LISite-specific N-glycosylation levels provide prognostic information distinct from, and often superior to, their carrier protein abundance, offering novel early-risk biomarkers. C_LI

Background & Aims: People with HIV (PWH) who achieve hepatitis C virus (HCV) cure may retain persistent metabolic alterations, particularly those with advanced fibrosis or cirrhosis. This study aimed to characterize plasma metabolomic and lipidomic profiles associated with cirrhosis in PWH at one and five years post-HCV therapy. Methods: Two cross-sectional studies evaluated PWH one (n=48) and five (n=30) years post-HCV therapy. Cirrhosis was defined as a liver stiffness measurement (LSM)[&ge;]12.5 kPa. Metabolomics and lipidomics were performed using capillary electrophoresis-mass spectrometry (CE-MS) and liquid chromatography-mass spectrometry (LC-MS), respectively. Data were analyzed using orthogonal partial least squares discriminant analysis (OPLS-DA) and generalized linear models (GLM), adjusting for relevant covariates. Results: At one and five years, 32 (66.7%) and 10 (33.3%) participants, respectively, had cirrhosis. OPLS-DA identified 235 and 229 metabolites with variable importance in projection (VIP)scores >1. At one year, cirrhosis was associated with elevated levels of glycerophospholipids, sphingomyelins, and amino acids, and lower levels of triglycerides. At five years, cirrhotic PWH exhibited higher levels of glycerophospholipids and acyl-carnitines, together with lower levels of triglycerides and amino acids. Conclusions: PWH with cirrhosis post-HCV cure exhibits a persistently altered metabolic profile stable for five years, suggesting ongoing liver disease progression. These findings underscore the need for continued long-term monitoring of this population.

Rheumatoid arthritis is a prototypical autoimmune disease, characterised by prolonged systemic autoimmunity prior to organ-specific tissue inflammation. To achieve the contemporary goal of autoimmune disease prevention, a nuanced understanding of the transition from systemic autoimmunity to tissue-specific inflammation is critical. Here, we sought to identify immune signatures associated with the transition to subclinical joint inflammation detected by multi-joint ultrasound in anti-citrullinated protein antibodies (ACPA+)-positive individuals who imminently progress to RA. To achieve this, we performed single-cell transcriptomic and proteomic profiling on prospectively collected blood samples from high-risk ACPA+ imminent progressors, who were further stratified by the presence or absence of ultrasound (US)-detectable subclinical synovitis and compared them with ACPA+ non-progressors. We found type-1 interferon (IFN-I) activation in circulating CD14+ classical monocyte and GZMK+ CD8+ T cells preceding subclinical joint inflammation in ultrasound-negative (USneg) future progressors. In contrast, US-positive (USpos) future progressors exhibited a phenotypic shift in CD14+ classical monocytes towards IL1B+ expression and clonal expansion of GZMB+ cytotoxic CD8+ T cells at the onset of subclinical synovitis. Plasma proteomics also revealed a shift from Toll-like receptor-associated innate pathways in USneg future progressors toward effector and tissue-remodeling signatures in USpos future progressors. These findings suggest IFN-I-driven immune priming in specific immune subsets precedes the onset of subclinical joint inflammation, whereas tissue-directed inflammatory and cytotoxic programmes emerge at the onset of joint inflammation when clinical RA is imminent.

Background & AimsEarly identification of decompensation in patients with cirrhosis is important to enable timely detection, management of complications and for effective treatment. This study investigates the biology of decompensation and aim to identify protein biomarkers for identification of high-risk patients. MethodsThe primary analysis included plasma samples from 46 patients with metabolic dysfunction associated steatotic liver disease (MASLD) related cirrhosis. Plasma samples were depleted for the top 14 most abundant proteins and the proteome was measured by liquid chromatography tandem mass spectrometry. The dataset was divided into a training (14 compensated, 10 decompensated) and a test cohort of compensated patients (11 progressing to decompensation, 11 remaining compensated). Changes in protein levels were determined by ANCOVA and a prognostic model was developed using logistic regression. External validation was performed in an independent cohort of 120 patients with alcohol-related cirrhosis. Time-to-event analyses were conducted in this cohort using Cox regression. Results52 proteins involved in impaired hepatic function, fibrogenesis, immune activation, and metabolic changes were significantly different between compensated and decompensated patients. A prognostic model with four proteins (NBL1, LTBP4, APOC4, GHR), demonstrated predictive ability for future decompensation (AUC=0.93, 73% sensitivity, 100% specificity). In the external validation cohort, the model demonstrated generalizability (AUC=0.78, 72% sensitivity, 82% specificity). Validation cohort time-to-event analyses showed that higher baseline scores were associated with shorter time to liver-related events (HR 1.32; log-rank p = 0.027), underscoring the panels prognostic value. ConclusionOur study indicates that patients with decompensated cirrhosis are characterized by proteomic signatures of fibrogenesis and metabolic dysfunction. Capturing these signatures could help identify patients at risk of complications and potentially those eligible for aetiology directed treatment. Impact and ImplicationsAddressing a critical unmet need for early detection of cirrhosis decompensation, our proteomic study identifies a four-protein panel with predictive ability for decompensation. These findings hold significant implications for hepatologists, clinical researchers, and healthcare systems, offering a novel tool to enhance prognostication and refine treatment strategies, potentially facilitating targeted patient monitoring. However, considering the small discovery sample size and the distinct aetiology of the external validation cohort, further validation is essential before broad clinical integration. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=183 SRC="FIGDIR/small/709475v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@6620e2org.highwire.dtl.DTLVardef@f8dfe4org.highwire.dtl.DTLVardef@1331101org.highwire.dtl.DTLVardef@1a195ca_HPS_FORMAT_FIGEXP M_FIG C_FIG

ObjectivesTransformative observations demonstrate unprecedented success of B cell-depleting interventions in many human autoimmune diseases, calling for a deeper understanding of the triggers leading to B cell-mediated autoimmunity and its perpetuation in human disease. Here, we investigated whether the autoreactive B cell response targeting human topoisomerase 1 (TOP1), a hallmark of systemic sclerosis, could cross-react with TOP1 of microbial origin. MethodsHomologies between human and microbial TOP1 were analyzed using Foldseek. TOP1-reactive monoclonal antibodies from patient-derived, human TOP1-reactive B cell receptors were generated and assessed for reactivity against human TOP1 and TOP1 from a prototypic yeast, Saccharomyces cerevisiae (S. cerevisiae). Reactivity of polyclonal serum IgG from anti-TOP1 autoantibody (ATA)+, anti-centromere autoantibody (ACA)+ SSc patients and healthy donors (HDs) was tested. Finally, B cell lines were generated expressing human ATA to study B cell activation upon antigenic stimulation. ResultsStructural homologues of human TOP1 were found in many microbes, particularly in fungi. Taking TOP1 from S. cerevisiae as a prototype, microbial TOP1 was recognized by polyclonal patient IgG and by several monoclonal ATAs. Importantly, S. cerevisiae TOP1 also activated B cells expressing a patient-derived, human TOP1-reactive B cell receptor. Patients affected by interstitial lung disease most frequently showed recognition of microbial TOP1. ConclusionsThese findings identify fungi as potential drivers of immune dysregulation in human autoimmunity, specifically in SSc, highlighting microbial antigen cross-reactive cells as important therapeutic targets. Moreover, these data provide first functional evidence for a breach of B cell tolerance against human TOP1 triggered by cross-reactivity to fungal TOP1.

Autoimmune inflammatory myopathies (AIM) with prominent B cell aggregates (BCM) on muscle biopsy is an uncommon finding. We aimed to compare the characteristics and clinical course of patients with BCM on muscle biopsy to those without and characterize B cell infiltrates in the muscle of these patients. We performed a retrospective study of subjects with AIM in the Canada Inflammatory Myopathy Study (CIMS) cohort to identify cases with BCM on muscle biopsy, which was defined as [&ge;]30 CD20+ cells/aggregate. AIM cases without BCM that encompassed the broader spectrum of AIM, namely dermatomyositis, overlap myositis and inclusion body myositis were selected as controls. Descriptive statistics were used to compare BCM cases and controls. Cyclic immunofluorescence (Cyc-IF) was performed to characterize inflammatory infiltrates and B cell structures. We included 69 subjects (mean age at diagnosis 51{+/-}16 years, 77% females): 22 BCM, 24 dermatomyositis, 14 overlap myositis, and inclusion body myositis. Most BCM subjects (18/22, 82%) had an associated autoimmune disease: 12 (55%) had systemic sclerosis, 5 (23%) rheumatoid arthritis and one (5%) systemic lupus erythematosus/systemic sclerosis overlap. Extra-muscular features found in BCM patients included arthritis (50%), interstitial lung disease (43%), Raynauds phenomenon (32%), and dermatomyositis rash (27%). Two patients (9%) had facial muscle weakness and one (5%) had positive anti-AChR autoantibodies. In BCM subjects, upper extremities were weaker than lower extremities in 7/21 (33%) of cases. Neck flexor weakness was frequent (17/22, 77%), while neck extensor weakness was uncommon (1/15, 7%). Cyclic immunofluorescence (Cyc-IF) spatial analysis of BCM biopsies displayed many features akin to tertiary lymphoid structures. Findings suggest possible involvement of both the traditional germinal center reaction and the extrafollicular pathway in BCM. In conclusion, in this series of myositis with B cell aggregates reported to date we found clinical similarities (i.e., associated with overlapping autoimmune diseases) and differences (i.e., muscle weakness distribution) with previous reports. The discovery of tertiary lymphoid structures on spatial analysis of muscle biopsies of BCM patients provides novel insight into its pathophysiology and potential therapeutic targets.

Background: Patient matching in intensive care databases yields sample sizes too small for individualised outcome analysis. Current AI systems provide population-level guideline summaries but omit stratification variables that may invert therapy signals at the individual level. Methods: We developed the Therapeutic Distance framework, which computes the z-standardised distance between a patient's clinical parameters and the centroid of MIMIC-IV patients who received each therapy: d(P,T) = sum of wi(T) x |(Li - mui(T)) / sigmai|. We hypothesise that patients at the same distance to a therapy (same orbit) have comparable outcomes. Six validation experiments were performed on 11,627 sepsis patients (SAPS-II 30-80) from MIMIC-IV v3.1. Results: Echo-stratified vasopressin recipients showed mortality of 30.1% (n=146, 95% CI 22.6-37.7%) versus 53.9% without echo (n=2,426, 95% CI 51.9-55.9%). Confidence intervals did not overlap (bootstrap, 1,000 resamples). However, echo-stratified patients had lower general severity (SAPS-II 49.2 vs 53.9) but higher cardiac biomarkers (troponin 1.0 vs 0.51 ng/mL), indicating that the observed difference is compatible with both severity confounding and a possible cardiac-specific vasopressin effect. Leave-one-out prediction with uniform weights achieved AUC 0.61 as a structural baseline. Conclusions: Therapeutic Distance replaces patient matching with orbit matching, substantially increasing usable sample sizes. The echo-vasopressin finding is hypothesis-generating and mechanistically plausible but not causally proven. The framework is intended as a clinical decision support signal under uncertainty, not as a causal inference method.

BackgroundThe profound molecular heterogeneity of SLE remains a fundamental barrier to therapeutic progress. MethodsWe integrated clinical and multi-omic profiling, including transcriptomics, autoantigen microarrays, proteomics, and flow cytometry, across three randomised trials (BEAT-Lupus, CALIBRATE, ACCESS) and two observational cohorts to identify distinct lupus endotypes. FindingsUsing multivariate distance-based matching of autoantibody profiles to integrate molecular heterogeneity, we identified anti-RNP/anti-Sm co-positivity (RNP+Sm+) as a distinct myeloid-dominant inflammatory endotype. Enriched in patients of Black ancestry (approx. 50%), RNP+Sm+ SLE is characterised by expanded intermediate monocytes showing enhanced TLR4-driven inflammation during flares, elevated pro-inflammatory cytokines (TNF-alpha, IL-6, IL-12, IFN-gamma, CCL2), IFNA10-biased interferon signalling, and systemic metabolic activation. IgG autoantibody profiling confirmed epitope spreading to spliceosomes and novel autoreactivity against circadian-metabolic regulators (SIRT1, NCOA1, SREBF1). Clinically, this endotype manifests as high-grade disease activity (2.5-fold flare risk), nephritis, vasculitis, and enteritis. Hyperferritinaemia correlates with flares exclusively in RNP+Sm+ SLE (r=0.81), reflecting underlying macrophage activation. RNP+Sm+ patients exhibit profound therapeutic resistance: 44% failed first-line immunosuppression (rising to 61% in Black patients), while also showing substantially reduced efficacy (60% lower response) with second-line B-cell-depleting therapies (rituximab, obinutuzumab). Resistance to rituximab therapy was driven by rapid B-cell repopulation, rising BAFF levels, and sustained cytokines despite peripheral depletion. Consequently, they remain heavily steroid-dependent and accrued greater organ damage. ConclusionThe RNP+Sm+ signature defines a high-risk, refractory, myeloid-driven lupus endotype characterised by activity linked hyperferritinemia that likely requires therapies directed at the underlying interferon and myeloid-centred pathways. FundingBEAT-Lupus: Arthritis UK and GSK. ACCESS and CALIBRATE: National Institute of Allergy and Infectious Diseases of the NIH. Context and SignificanceSystemic lupus erythematosus (SLE) is immunologically heterogeneous, yet conventional classifications fail to predict therapeutic outcomes. While autoantibodies are central to diagnosis, whether specific combinations define mechanistically distinct subsets remains unresolved. Here, we demonstrate that anti-RNP/anti-Sm co-positivity (RNPSm) identifies a clinically aggressive, myeloid-dominant endotype disproportionately affecting Black patients. Multi-omics integration revealed expansion of intermediate monocytes with enhanced TLR4 expression, IFNA10-biased interferon signalling, and metabolic reprogramming. Clinically, RNPSm patients exhibit nephritis, vasculitis, higher flare rates, and profound first-line therapeutic resistance. Subsequently, this endotype shows poor response to B-cell-depleting therapies, necessitating prolonged glucocorticoid dependence and accelerated organ damage. Establishing RNPSm as a lupus endotype and ferritin as a companion disease activity biomarker enables precision stratification and highlights an underserved, high-risk population requiring urgent development of alternative strategies like myeloid-targeted and interferon-directed therapies. HighlightsO_LIAnti-RNP/Sm co-positivity defines a high-risk, flare-prone, myeloid-dominant SLE endotype C_LIO_LIRNPSm patients, especially Black patients, show profound refractoriness to first-line and B-cell depletion therapies C_LIO_LIExpanded intermediate monocytes with TLR4 upregulation and IFNA10-biased interferon signalling C_LIO_LIHyperferritinaemia correlates with disease activity exclusively in RNPSm patients C_LI