Clinical & Translational Immunology

Antibody Fc glycosylation is modulated in a variety of disease and immune response contexts, altering downstream functional responses including antibody-dependent cellular cytotoxicity through modified immune cell Fc receptor binding. Accessible, high-throughput glycosylation assays such as enzyme-linked lectin assays (ELLAs) are essential to advance understanding of glycosylation regulation and function. However, current ELLA protocols lack standardization and optimization, and results are reported out in arbitrary absorbance units, limiting reproducibility and cross-study comparability. We developed an optimized multi-lectin parallel ELLA with three specific improvements: systematic optimization of incubation times and reagent concentrations; incorporation of Protein A for IgG specificity; and use of commercially available bovine fetuin B as a quantitative surrogate standard for cross-study reproducibility. Our panel of 8 lectins, SNA, RCA, LCA, PHA-E, PHA-L, MAL-I, WGA, and DSL, cover the major IgG glycoforms. We demonstrate that our ELLA panel can reveal biologically relevant cytokine-induced plasticity of IgG glycosylation profiles in immortalized B cells.

Endothelial cells (ECs) are key players in maintaining homeostasis and coordinating immune responses, activating during acute inflammation to recruit immune cells. Endothelial heterogeneity has been found to impact transcription level differences across EC sources, but how these differences drive downstream effects in inflammatory signaling and immune interactions remains unclear. Here, we employed multiplexed ELISA to quantify secretion for 19 inflammatory factors following tumor necrosis factor (TNF) or Pseudomonas aeruginosa activation of four primary human EC sources: umbilical artery (HUAEC), umbilical vein (HUVEC), dermal microvascular (HDMEC), and pulmonary microvascular (HPMEC) endothelial cells. We also quantified changes in neutrophil adhesion to each EC source and used partial least squares regression (PLSR) to identify key inflammatory proteins associated with changes in neutrophil adhesion. We found distinct inflammatory secretion profiles across all cell types, with veinous ECs showing the highest basal secretion of most inflammatory proteins and pulmonary ECs exhibiting the lowest. Arterial ECs exhibited the lowest sensitivity to inflammatory stimulus, while pulmonary ECs exhibited dynamic responses following activation. Furthermore, inflammatory stimulus caused large differences in expression across cell sources for six factors: GM-CSF, IL-1{beta}, IL-6, IP-10, E-selectin, and ICAM-1. We found endothelial heterogeneity also contributed to differences in neutrophil adhesion to unstimulated ECs. Our PLSR analysis revealed five secreted factors most indicative of changes in neutrophil adhesion: E-selectin, ICAM-1, PECAM1, IL-6, and IL-8. Collectively, our findings strengthen the emerging view that vascular-bed specific differences in EC phenotype can impact downstream immune responses.

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.

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.

Background: Non-invasive diagnosis, reliable recurrence surveillance remain critical unmet needs in gliomas. Glioma induces profound systemic immune alterations despite its anatomical confinement to the central nervous system. Circulating immune cells, particularly monocytes, are key mediators of tumor-host crosstalk and may retain tumor-induced transcriptional imprints. However, their potential clinical utility as blood-based biomarkers for detection and monitoring, remain largely unexplored. Methods and findings: In this study, we performed integrated single-cell RNA sequencing of blood immune cells and demonstrated that circulating CD14+ monocytes are significantly expanded in glioma patients, exhibiting features of differentiation arrest and increased transcriptional plasticity. These cells harbor glioma-specific molecular signatures distinct from those observed in healthy controls and patients with other tumors. Leveraging these findings, we developed an ensemble machine learning diagnostic model based on transcriptomic profiles of circulating CD14+ monocytes (training cohort, n=107), which achieved a mean area under the receiver operating characteristic curve (AUC) of 0.971 during cross-validation. In an independent cohort of 567 participants, the model maintained high diagnostic accuracy, yielding an AUC of 0.877 for distinguishing glioma from controls and other tumors. And it achieved a recurrence detection AUC of 0.969 in 51 postoperative samples. Moreover, in a prospective follow-up study involving 30 glioma patients, lower model-derived scores of postoperation were significantly associated with prolonged progression-free survival (log-rank test, P=0.043), supporting its prognostic utility. Conclusion: We demonstrate circulating CD14+ monocytes undergo glioma-specific transcriptional reprogramming, generating systemic tumor-associated signal captured via transcriptomic profiling. This blood-based diagnostic model provides non-invasive, scalable approach for glioma detection, recurrence surveillance, outcome prediction.

Heart transplantation (HT) is the durable therapy for end-stage heart failure (HF). Despite advances in immunosuppression, cardiac allograft vasculopathy (CAV) remains a leading cause of late graft failure and mortality in the modern era. Prior studies have established donor age and immunological phenomena, such as acute cellular rejection (ACR), antibody-mediated rejection (AMR), and development of donor-specific antibodies (DSAs) as risk factors for CAV. However, it remains unclear whether acute rejection (AR) that occurs early post-HT, when individuals experience the highest degree of immunosuppression, reflects higher baseline immune activity and confers a higher risk of future CAV compared to later AR, when immunosuppression is minimized. We therefore examined whether AR occurring during pre-specified early and intermediate intervals compared to those who did not experience AR in the first post-HT year was associated with future CAV among recipients without CAV at 1 year.

Immune phenotyping represents a pillar in diagnostics, characterization of new genetic defects, and understanding mechanisms of diseases. Cell population distribution often does not cover the intrinsic function changes that may contribute to disease. Outcome of signaling activation can be used as proxy for cell function. To overcome the limitation of sample availability and standardization of signaling assays, we developed a multiplex full spectrum cytometry phosphoflow assay allowing the study of 6 phospho-proteins representing BCR/TCR, MAPK, PI3K/Akt/mTOR and canonical NF-{kappa}B signaling pathways in 18 immune cell subpopulations. Maximal stimulation and temporal dynamics were studied in response to pan-stimuli, activating cells regardless of receptor, and targeted stimuli for T, B, and innate immune cells. We studied healthy individuals between 1-69 years and discovered subpopulations-specific responses. Furthermore, pediatric donors showed broad differences in B cell and T cell function compared to adults. Hence, we established a tool to assess multiple signaling pathways at once and provide age- and subpopulation-specific references for signaling outcome. SummaryMultiplex full spectrum flow cytometry-based phosphoflow assay across 18 immune cell subpopulations, 6 phospho-proteins in response to 6 stimuli at 4 time points in individuals aged 1-69 years, reveals distinct age- and subpopulation-associated signaling patterns in magnitude and dynamics of pathways activation.

Acute respiratory distress syndrome (ARDS) is a devastating complication of respiratory infections; however, the biological mechanisms that initiate its onset are poorly defined. Here we show that TNFRSF13B polymorphisms increase the risk of ARDS following SARS-CoV-2 infection up to 7.4-fold compared to the WT genotype. The increased risk was not due to immune-deficiency or impaired virus neutralization. On the contrary, TNFRSF13B mutant subjects mounted better antibody neutralization compared to subjects with WT TNFRSF13B. However, IgG from subjects expressing TNFRSF13B variants had less sialic acid, terminal galactose, and fucose than IgG from subjects with a WT genotype. Moreover, IgG from TNFRSF13B mutant subjects exhibited increased recruitment of complement factors. Thus, besides well-known actions governing plasma cell differentiation, TNFRSF13B impacts both affinity maturation and effector functions of IgG in ways that independently govern complement activation controlling inflammatory responses known to trigger ARDS.

Haemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening hyperinflammatory syndrome characterised by uncontrolled immune activation. Reduced high- and low-density lipoprotein cholesterol and hypertriglyceridaemia are reported in HLH, suggesting lipid metabolism disturbances although in-depth serum metabolomic analysis is lacking in HLH. Here a lipid-focused NMR spectroscopy platform was used to define the serum metabolomic landscape of adults hospitalised with HLH compared to adults with sepsis (HLH-mimic) and rheumatic disease (potential HLH drivers/triggers), following surgical resection of solid organ cancer (non-infectious acute inflammation controls) and healthy controls (HCs). Serum metabolites distinguished HLH from HCs with high accuracy (>91.36%) using multiple machine learning models. The top classifying features included elevated apolipoprotein-B (ApoB)-containing low, intermediate, and very low-density lipoprotein particles; and lipoprotein remodelling towards triglyceride enrichment and cholesterol depletion. Differentially abundant metabolites in HLH compared to all control groups were enriched in pathways related to lipid metabolism including: 'Lipid particles composition', 'Plasma lipoprotein clearance', 'Plasma lipoprotein remodelling', 'Glucose homeostasis' and 'Amino acid metabolism'. Metabolomic results were validated using matched whole blood RNA-sequencing which identified differentially expressed genes enriched in metabolic modules associated with lipid, amino acid, and glucose metabolism, supporting a coordinated metabolic dysregulation in HLH from a transcriptomic to metabolomic level. Finally, twenty-seven metabolites including ApoB-containing, triglyceride-rich lipoproteins and saturated fatty acids distinguished HLH from all disease controls (AUC>0.70) either alone or combined as a metabolomic signature. Elevated ApoB and ApoB:ApoA1 ratio in HLH vs sepsis and HCs were validated by ELISA, supporting their utility as biomarkers to distinguish HLH from other hyperinflammatory syndromes.

The neutralizing activity present in human serum is considered a correlate of protection against SARS-CoV-2 infection and disease but the mechanisms by which serum antibodies are transported into the lumen of the respiratory tract, where they are required to interact with virus particles and infected cells remain incompletely understood. The transcytosis and neutralizing activity of serum-derived IgG and IgA antibodies was investigated using an in vitro SARS-CoV-2 infection model with primary differentiated human nasal and basal epithelial cells (hNECs and hBECs) cultures. Expression of the antibody transport receptors neonatal Fc receptor (FcRn) and polymeric immunoglobulin receptor (pIgR) in hNECs cultures was confirmed by qPCR, immunofluorescence microscopy, and flow cytometry. Both receptors were expressed throughout the epithelial cultures, with enriched expression observed in ciliated cells compared with goblet and basal cells. Purified IgG and IgA isolated from convalescent plasma demonstrated specificity for SARS-CoV-2 spike protein and inhibited ACE2-Spike interactions, although activity was reduced against later variants. Purified IgG contained higher anti-spike antibody titers than purified IgA. Functional neutralization assays showed that transcytosed IgG and IgA significantly reduced SARS-CoV-2 infection compared with untreated controls. However, serial dilution studies demonstrated that IgG-mediated neutralization was more potent than IgA-mediated neutralization. Similar results were determined for influenza A virus H3N2 subtype. The transcytosis of IgG was more efficient in hBEC cultures while IgA transcytosis was higher in hNEC cultures, reflecting the levels of the corresponding transport proteins. Together, these findings demonstrate that serum-derived IgG and IgA can undergo transepithelial transport across human nasal epithelium while retaining SARS-CoV-2 or influenza A virus neutralizing activity in vitro. These results suggest that FcRn- and pIgR-mediated antibody transport may contribute to mucosal protection following vaccination or infection and may help identify antibody responses associated with protection against SARS-CoV-2. ImportanceSerum antibody levels are considered correlates of protection for SARS-CoV-2 and Influenza A virus but its unclear how those antibodies are transported to the apical surface of respiratory epithelial cells, where they must be present for optimal activity. We show that IgG and IgA specific for SARS-CoV-2 or influenza A virus is transcytosed across respiratory epithelial cell cultures, the efficiency of which reflects the level of FcRn or pIgR expression levels, suggesting that cells of the upper and lower respiratory tract transport different antibodies from the blood.

Congenital heart defects (CHDs) are the most common form of fetal malformation however, our understanding of trophoblast health and communication throughout gestation in CHD pregnancies remains limited. The purpose of this study was to assess extracellular vesicles (EVs) and microRNA (miRNA) present in maternal and umbilical cord plasma from a spectrum of CHD subtypes during gestation and at time of delivery. We hypothesized that circulating placenta-derived EVs and miRNA will differ in CHD when compared to controls. Maternal plasma samples were collected between 16-24 weeks of gestation and at the time of delivery. Umbilical cord plasma was obtained following delivery. EVs were isolated from plasma samples using nanoscale flow cytometry, and total EV counts as well as counts by cellular origin were determined. MicroRNA was extracted from maternal plasma and levels quantified using qPCR. Maternal plasma from pregnancies complicated by fetal CHD exhibited higher total EV counts at delivery compared to control. Platelets derived extracellular vesicles (pdEVs) were significantly higher both in maternal and cord blood plasma at the time of delivery in CHD pregnancies compared to gestationally age-matched control pregnancies. Circulating miR22 and miR421 levels were reduced, while miR29c levels were increased in maternal plasma from CHD pregnancies between 16-24 weeks but no differences seen at time of delivery. Pregnancies complicated by CHD are associated with an altered in utero environment by changes in extracellular vesicles and miRNA profile in maternal serum. Circulating EVs and miRNA profiles may therefore serve as minimally invasive indicators of placental and maternal vascular dysfunction in CHD.

Background: Hypertensive disorders of pregnancy (HDP) may first be diagnosed antepartum, during labor, or postpartum. We utilized untargeted large-scale proteomics to identify pathways associated with HDP based on timing of onset. Methods: We performed a nested case-control study comparing differential protein expression, from the SomaScan 7K platform, based on timing of onset of HDP versus controls (referent) using first-trimester samples from the NuMoM2b-Heart Health Study, a multi-site cohort that followed nulliparous individuals from the first trimester. Associations of proteins with timing of onset of HDP, adjusted for co-variates, were assessed using logistic regression q value-based false discovery rates and pathway enrichment and differential expression analysis were conducted. Results: Of 1628 individuals included, 678 had HDP, of which 67% manifested antepartum (AP), 29% intrapartum (IP), and 3% postpartum (PP). After adjusting for co-variates, compared to controls, 698 proteins, 39 proteins, and 144 proteins were differentially expressed in those with HDP according to AP, IP, PP onset, respectively. There was little overlap in individual protein expression based on timing of HDP. Pathway enrichment and graphical summary analyses suggested distinct processes. Specifically, there was downregulation of angiogenic proteins in AP HDP, downregulation of immune-related proteins in IP HDP, and upregulation of complement activation promoting fibrotic changes leading to cardiac dysfunction in PP HDP. Conclusion: There are differences in first-trimester protein expression based on whether HDP first manifests AP, IP or PP. This raises the possibility that there may be distinct mechanistic phenotypes that could uniquely inform diagnostic and therapeutic targets for HDP.

Antibody-dependent enhancement (ADE) is a major concern across orthoflavivirus infections, yet how multiple viral exposures shape enhancement risk remains incompletely understood. Here, we integrated serosurveillance from Saude, Brazil with functional immunologic analyses to define how yellow fever virus (YFV)-associated orthoflavivirus immune histories influence ADE phenotypes. Using serocomplex-specific anti-premembrane antibody profiling validated by microneutralization assays, plasma samples were stratified into YFV-only, YFV+DENV, and YFV+DENV+ZIKV exposure groups. In Fc gamma receptor-bearing U937 cells, YFV-only plasma demonstrated minimal enhancement activity, whereas cumulative orthoflavivirus exposure generated broader ADE phenotypes across heterologous viruses. In IFNAR1-/- passive-transfer models, YFV-only plasma did not enhance ZIKV or DENV2 infection in vivo. In contrast, YFV+DENV plasma increased ZIKV viremia and accelerated mortality kinetics, while YFV+DENV+ZIKV plasma demonstrated concentration-dependent enhancement phenotypes. Collectively, these findings indicate that isolated YFV immunity does not predispose to ADE, whereas cumulative orthoflavivirus exposure generates antibody repertoires capable of producing concentration-dependent enhancement in vivo.

Early pregnancy requires a tightly regulated pro-inflammatory environment shared between the primitive placenta and decidua. While immune balance supports successful implantation and placental invasion, disruptions in immune signaling during this period can impair implantation and lead to embryo loss. In this study, we investigated the molecular mechanisms underlying immune imbalance during implantation using a trophoblast stem cell (TSC) model. TSCs were cultured in either stem cell or syncytiotrophoblast (STB) differentiation medium and treated with either lipopolysaccharides (LPS) or interferon beta (IFNB). RT-qPCR and Western blotting revealed that LPS failed to induce a pro-inflammatory cytokine response in TSCs or STBs. In contrast, IFNB triggered a strong antiviral response in both TSCs and STBs. RNA-sequencing of IFNB-treated TSC and STB 3D spheroids revealed subtle differences between the TSCs and STB responses to interferons. Both TSC and STB IFNB-treated spheroids mount an interferon-mediated antiviral response; however, STB spheroid genes associated with the type I interferon response, viral RNA/DNA sensing, and antigen processing were upregulated. We also compared the interferon response between the CT27 (female) and CT29 (male) TSCs and STBs. While STBs showed minimal differences, the CT29 TSCs exhibited a markedly stronger interferon response than the CT27 TSCs. Collectively, these findings suggest that the primitive placenta is selectively responsive to interferon signaling rather than direct pathogen-associated stimuli. This implies that maternal immune activation, rather than microbial invasion, likely drives that placental immune response and embryo success at this stage. Understanding these dynamics underscores the importance of the maternal immune balance in early pregnancy success.

SRC knockdown inhibits trophoblast cell proliferation, migration, and invasion while inducing apoptosis via activation of the PI3K/Akt/Bcl-2 signaling pathway. Trophoblast dysfunction is central to pregnancy disorders such as preeclampsia and miscarriage, yet the role of SRC, a non-receptor tyrosine kinase, in these cells remains poorly understood. This study aimed to elucidate the functional impact of SRC on trophoblast behavior and its underlying mechanism. Using siRNA-mediated knockdown in HTR8/SVneo cells, we confirmed efficient reduction of SRC mRNA and protein expression via RT-qPCR and Western blot. Functional assays demonstrated that SRC silencing significantly suppressed cell proliferation (CCK-8), migration (wound healing), and invasion (Transwell), while promoting apoptosis, evidenced by increased Annexin V-FITC/PI staining and upregulated Caspase-3 and Caspase-9 protein levels. Mechanistically, Western blot analysis revealed that SRC knockdown upregulated PI3K, Akt1, and Bcl-2 protein expression without altering IRS1 levels, indicating activation of the PI3K/Akt/Bcl-2 pro-survival pathway. This paradoxical activation appears to be a compensatory feedback insufficient to overcome SRC loss-induced dysfunction. Our findings identify SRC as a critical positive regulator of trophoblast proliferation, motility, and survival, acting through a non-canonical, IRS1-independent negative regulation of PI3K/Akt signaling. This study provides novel insights into trophoblast biology and suggests SRC as a potential therapeutic target for pregnancy complications; future in vivo studies are warranted to validate these mechanisms.

The bone marrow (BM) vascular network plays crucial roles in driving bone development and supporting hematopoiesis, yet the mechanisms governing its specialized architecture, particularly sinusoidal morphogenesis, remain inadequately characterized. We show in this study that TIE2 (Tek) was highly expressed by BM sinusoidal endothelial cells (SEC) and the endothelial Tek excision led to BM sinusoidal capillarization. Particularly, the BM sinusoids displayed thinner vessel diameter with the aberrant mural cell coverage in the Tek mutants. Mechanistically, TIE2 insufficiency led to a dramatic decrease of VEGFR3 in BM-SECs while its expression in hepatic sinusoids was not obviously altered. The RNA-seq analysis showed that GO terms enriched for the downregulated genes were related to the biological processes including sinusoidal development while pathways related to arterial ECs and angiogenesis were upregulated in the bone marrow of Tek mutants. The alteration of sinusoidal VEGFR3 expression occurred within 48 h after the induced endothelial deletion of Tek. Consistently, the defective BM sinusoidal formation was validated with the induced Tek deletion in VEGFR3+ SECs. The insufficiency of TIE2 ligand ANGPT1 also led to reduced sinusoidal VEGFR3, accompanied by similar BM sinusoidal defects. Furthermore, disruption of sinusoidal morphogenesis was observed in mutant mice with the endothelial excision of Nr2f2 (COUP-TFII), displaying a decreased expression of BM sinusoidal TIE2 and VEGFR3. These findings suggest that ANGPT1/TIE2 and COUP-TFII form a reciprocal regulatory loop to coordinate BM sinusoidal specification via regulating VEGFR3.

BackgroundImmunoglobulin E (IgE) plays a fundamental role in the pathogenesis of allergic disease, including asthma. The IgE-producing plasma cells (PCs) are thought to persist indefinitely, providing a sustained source of allergen-specific IgE. Although these cells can accumulate in the bone marrow (BM), after prolonged allergen exposure, their frequency remains remarkably low, and the mechanisms that regulate their migration are poorly understood. ObjectiveTo investigate the chemokine receptor profile and the migration potential of the human IgE-producing cells. MethodsTonsil B cells were stimulated with IL-4 and anti-CD40 to induce class switching to IgE and IgG1. The chemokine receptor profile of IgE+ and IgG1+ switched cells was determined using flow cytometry and migration towards relevant chemokines was quantified using transwell chemotaxis assays. Chemokine expression was also validated by re-analysis of a published single cell RNA sequencing (scRNAseq) dataset of PCs isolated from nasal polyps (NP) of patients with allergic fungal rhinosinusitis. ResultsIgE PCs exhibit significantly reduced expression of the BM-homing chemokine receptor CXCR4 and impaired migration towards its ligand, CXCL12. While IgE+ PCs can upregulate CCR10 and respond to its ligand, CCL28, this behaviour is similar to IgG1+ PCs. Strikingly, however, IgE PCs selectively upregulate CCR2 and migrate robustly towards its ligand CCL2. Re-analysis of NP scRNAseq data confirmed that IgE PCs express significantly higher levels of CCR2 compared with PCs of all other isotypes. ConclusionsThese findings identify CCR2 as a key regulator of IgE PC migration and provide insights into their homing preferences that may shape the nature of the IgE responses.

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

Purpose: To characterize peripheral immune alterations in treated birdshot uveitis (BU) patients using high-dimensional mass cytometry and multiplex serology. Design: Cohort study. Subjects: 36 BU patients on immunomodulatory treatment (IMT) and 31 healthy controls (HCs). Methods: Detailed ophthalmologic examinations were performed, and peripheral blood and serum samples were collected for immune profiling using mass cytometry and multiplex cytokine analysis. Main Outcome Measures: Imaging-based indicators of ocular inflammation; peripheral immune cell frequencies; serum cytokine levels. Results: Compared to HCs, BU patients showed increased frequencies of Th17, CD146+ T cells, intermediate effector/central memory T cells co-expressing CXCR3 and CCR4, CD56dim NK cells and elevated IL-18 levels. Patients were clinically stratified by an expert ophthalmologist into three disease activity groups: Inactive, Active (comprising combinations of surface retina, deep retina and choroid activity) and Burned-out. Inactive patients harbored more quiescent effector T cells, e.g. Tim-3+ Tc17-Tc22 intermediates and more CD8+ TSCM, potentially representing a resting pool of autoimmune T cells. Active patients exhibited increased in vivo activation of relevant T cells, with stronger HLA-DR, CD38 or PD-1 expression, and highest levels of CD56dim NK cells. Immune profiles were also linked to treatment subgroups: csDMARDs (conventional synthetic disease-modifying antirheumatic drugs) were associated with higher CD56bright NK frequencies, and absence of therapy showed elevated PD-1/SLAMF7 Tc17+1 and PD-1CD57 CD8 TEMRA cells. IL-6R blockade (tocilizumab) resulted in loss of IL-6R T-cells accompanied by increased SLAMF7 T cells, due to epitope masking. Conclusions: Peripheral CyTOF profiling anchored to thorough clinical stratification revealed disease activity-associated immune signatures and therapy-associated imprints in BU.

BackgroundUndetectable HIV-specific antibodies in early-treated children with confirmed infection correlate with low viral reservoir and may identify those eligible for future HIV remission strategies. The neonatal immune systems unique characteristics, combined with impairments resulting from exposure to maternal HIV and antiretroviral treatment (ART), may affect antibody responses to HIV. Yet immune competence remains understudied in the context of negative HIV serology. The ANRS-EP59-CLEAC study included 76 children and adolescents with HIV. We measured plasma HIV antibodies by enzyme immunoassay, other analytes by ELISA or multiplex assays, and blood cell phenotypes and functions by flow cytometry. We used Fishers and Mann-Whitneys tests and logistic regression to analyze variables associated with negative HIV serology. Nine participants tested negative for HIV-specific antibodies, eight children and one adolescent. Negative HIV serology occurred exclusively in participants who had initiated ART early and had HIV RNA < 50 copies/mL at evaluation. Among 17 early-treated children with sustained viral suppression, only 7 had negative HIV serology. In this subgroup, negative HIV serology associated with higher nadir CD4 counts, lower plasma IgM levels, higher frequencies of circulating follicular CD8 T lymphocytes, and higher expression of the costimulatory molecule CD86 on myeloid dendritic cells. We found no evidence of B or T lymphocyte deficits associated with negative HIV serology. Low antigenic exposure was necessary but insufficient to explain negative HIV serology. Beyond its association with low HIV reservoir, negative HIV serology correlated with less severe prior CD4 T-lymphocyte depletion and higher frequencies of follicular CD8 T lymphocytes. SummaryIn HIV-infected infants, starting antiretroviral therapy (ART) very early dramatically improves health outcomes. An important phenomenon observed in some of these children is that, despite being HIV-infected, they show no detectable antibodies against the virus -- a profile referred to as negative HIV serology. This feature could help identify patients most likely to benefit from future strategies aimed at achieving long-term virus control without treatment. To better understand this phenomenon, we studied HIV-infected children and adolescents enrolled in the ANRS-EP59-CLEAC trial, which compares the effects of ART initiated early (before 6 months of age) versus late (after 24 months). We showed that negative HIV serology is associated with early treatment, but also with a better-preserved immune system: less depletion of CD4 T cells, which are critical immune cells, and a higher abundance of specific T lymphocytes with potent antiviral activity. Importantly, we found no evidence of defects in the mechanisms responsible for antibody production. These findings suggest that negative HIV serology reflects a favorable immunological profile and could serve as a useful marker to select children as candidates for HIV remission trials.