Browse Articles

Investigating the Role of IL-27 During Gram-Positive Neonatal Sepsis 2257867

Abstract Introduction Human newborns exhibit increased risk of bacterial sepsis. Interleukin (IL)—27, an immune-suppressive cytokine has been found to be elevated in neonatal human cells and mice. Prior work from our lab has demonstrated that IL-27 is detrimental to neonatal mice during gram-negative sepsis. In the present work, we aimed to understand the role of IL-27 in a gram-positive neonatal sepsis model with a focus on S. agalactiae (GBS), a leading cause of neonatal sepsis. Methods Neonatal C57BL/6 (WT) and IL-27 receptor-deficient (IL-27Rα-/-) mice were subcutaneously infected with GBS on day 4 of life. Morbidity and mortality were evaluated over 7 days. This included tissue-specific measurements of inflammatory markers and bacterial burdens. In addition, bone marrow-derived macrophages (BMDMs) from WT and IL-27Rα-/- neonatal mice were infected with GBS in vitro to evaluate bacterial clearance. Results Mice deficient in IL-27 signaling exhibited improved survival, weight gain, and maintenance of blood glucose levels following GBS infection compared to WT littermates. These aligned with reduced bacterial burdens in blood and peripheral tissues of IL-27Rα-/- pups. In response to GBS infection, WT pups displayed a tissue-specific increase in IL-27 gene expression. Furthermore, IL-27Rα-/- BMDMs demonstrated more efficient clearance of GBS than WT BMDMs in vitro. While IL-27 is known to be associated with suppressed inflammation, IL-27 signaling was associated with an increased inflammatory cytokine response during neonatal sepsis. In contrast to our prior E. coli model, was a slower progression of disease with a critical window for morbidity and mortality occurring at 48-72 h post-infection. Conclusion Our findings reveal that IL-27 signaling correlates with increased morbidity and mortality in GBS-infected neonatal mice. This suggests that IL-27 compromises the host response during neonatal GBS sepsis and may represent a target for therapeutic interventions. Funding Source NIH Funding Topic Categories Innate Immune Responses and Host Defense: Cellular Mechanisms (INC)

CCR4 is required for negative selection and suppression of Treg development by modulating interactions with and functions of thymic APCs 2234270

Abstract Introduction Chemokine receptors play a critical role in guiding thymocytes into the medulla where they encounter antigen presenting cells displaying diverse self-antigens that induce central tolerance. Thymocytes expressing a T-cell receptor (TCR) with high affinity for these self-peptides undergo negative selection or become regulatory T cells (Tregs). We have shown that the chemokine receptors CCR4 and CCR7 promote the medullary accumulation and negative selection of distinct thymocyte subsets, raising the question of whether CCR4 and CCR7 have distinct impacts on thymocyte selection. Methods TCR repertoire analysis was carried out on newly generated CD4+ single positive (CD4SP) thymocytes and Treg, along with in vitro assays, imaging, and flow cytometric analyses of thymocytes from Ccr4 or Ccr7 deficient mice. Results These studies reveal a significant impact of CCR4, but not CCR7, on the CD4SP repertoire, identifying TCR clones that require CCR4 for negative selection. Notably, while CCR7 is necessary for selection of Treg TCRs, CCR4 inhibits selection of Treg TCRs, revealing opposite impacts of these chemokine receptors on the Treg repertoire. Thymocyte intrinsic expression of CCR4 does not account for impaired Treg selection. Instead, recirculating Tregs express CCR4, enabling close contact with thymic dendritic cells and suppression of new Treg selection. Conclusion Our work further clarifies the importance of CCR4 for negative selection and identifies a novel role for CCR4 in regulating Treg selection. Funding Source NIH/ NIAID R01AI104870 Topic Categories Hematopoiesis and Immune System Development (HEM)

The adjuvant effect of an Il12 mRNA-LNP reveals a role for CD4+ T cell-dependent DC licensing in the CD8+ T cell response to mRNA vaccination 2331202

Abstract Introduction The use of mRNA lipid nanoparticles (mRNA-LNPs) provides a modular platform that allowed for rapid development of vaccines against SARS-CoV-2. Previous studies showed that the CD8+ T cell response generated by these vaccines is independent of CD4+ T cell help, type I conventional dendritic cells and IL-12. However, inclusion of an Il12 mRNA-LNP in an mRNA-LNP vaccine led to enhanced expansion of vaccine-specific CD8 T cells that were more functional upon restimulation. The signals involved in generating a T cell response to mRNA vaccination are incompletely understood, and the inclusion of additional mRNA components further complicates our understanding of these processes. Methods Mixed transfer of WT and IL-12R deficient OT-I T cells were used to assess the role of direct IL-12 signaling on CD8+ T cells. CD40L deficient, cDC1 deficient and CD4+ T cell depleted mice were used to assess the contribution CD4+ T cell dependent DC licensing to CD8+ T cell responses. Spatial transcriptomic analysis of lymph nodes was performed to assess early differences in mice given a standard vaccine or IL-12 adjuvanted vaccine. Results The use of IL-12R deficient OT-I T cells shows that the effects of IL-12 on CD8+ T cell expansion are independent of the ability of CD8+ T cells to respond to IL-12. Rather, spatial transcriptomic data reveals enhanced co-stimulatory protein and receptor expression that persist longer in IL-12 adjuvanted vaccination than in vaccination with standard mRNA-LNP. Incorporation of IL-12 results in enhanced effector CD4+ T cell responses, and we find that enhanced CD8+ T cell expansion is entirely dependent on CD4+ T cells, cDC1s, and CD40L. Conclusion Our data sets suggest that IL-12 induces CD4+ T cells to promote DC licensing via CD40-ligand and this process mediates the enhanced expansion of CD8+ T cells. Thus, the ability of an IL-12 mRNA adjuvant to amplify vaccine-induced CD8+ T cells relies on the engagement of pathways that are otherwise not engaged by standard mRNA vaccination. Funding Source Basser Center for BRCA Topic Categories Vaccines and Immunotherapy (VAC)

IFN-γ—Driven Activation Restricts Systemic Infection by a Minimal Effector Strain of Salmonella Typhimurium and Is Overcome by T3SS Effectors 2258032

Abstract Introduction Salmonella enterica serovar Typhimurium (STm) employs a type III secretion system (T3SS) to translocate effector proteins that enable intracellular survival and replication. Through targeted mutagenesis and phenotypically guided genome reassembly, we identified a minimal set of SPI-2—encoded effectors sufficient for intracellular replication in vitro (STmθ). Although this effector module is conserved across S. enterica serovars, these genes alone are insufficient to promote systemic virulence in vivo without the addition of an accessory T3SS effector locus, suggesting the presence of host immune barriers that restrict STm θ dissemination. Methods To define immune barriers limiting STm θ in vivo, we used intraperitoneal (IP) infection models in mice deficient in MyD88 or interferon-γ (IFN-γ) signaling. We developed an STm-specific anti-LPS antibody to track bacterial association with immune subsets by CyTOF. To mechanistically dissect this restriction, we modeled infection in bone marrow—derived macrophages (BMDMs) with or without IFN-γ pre-treatment. Results Survival and bacterial burden analyses revealed that IFN-γ is the dominant host pathway restricting systemic dissemination of STm θ, while MyD88 signaling plays a route-dependent role, limiting infection of T3SS-deleted strain (effectorless) after intragastric (IG) but not IP challenge. High-dimensional CyTOF profiling demonstrated IFN-γ—dependent expansion and occupancy of immune subsets with STm LPS that restrict STm θ. IFN-γ pre-treatment reduced STm θ replication in BMDMs but had little effect on strains expressing additional T3SS effectors, indicating resistance to macrophage-intrinsic IFN-γ—mediated restriction Conclusion These findings identify IFN-γ as a central barrier to STm θ dissemination and reveal route-specific roles for MyD88 signaling in limiting bacterial pathogenesis. This work provides a framework to define how additional accessory T3SS effector subvert innate immune defences to enable systemic infection. Funding Source NIH, The Welch foundation, Burroughs Wellcome Fund Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Host Peroxisome Proliferator-Activated Receptor Alpha is Essential for Coxiella burnetii Intracellular Survival and Prostaglandin E2 Production 2307362

Abstract Introduction The obligate intracellular bacterium Coxiella burnetii causes Q fever, often leading to chronic endocarditis, which reflects the bacterium’s capacity for long-term survival within host cells. Our research shows that Coxiella manipulates host lipid storage organelles, known as lipid droplets (LDs), in alveolar macrophages. The breakdown of these LDs is crucial for bacterial growth, as it releases precursors necessary for the production of the immunosuppressive molecule, prostaglandin E2 (PGE2). This LD breakdown-mediated PGE2 production is essential for Coxiella survival, but the host transcriptional mechanisms mediating this process have been unclear. We hypothesized that host Peroxisome Proliferator-Activated Receptors (PPARs)–transcription factors vital for macrophage lipid metabolism and immune modulation–play a significant role in Coxiella intracellular survival. Methods To test this, we used subtype-specific PPAR agonists and antagonists and measured bacterial growth. Results We found that altering PPARα activity significantly decreased Coxiella growth. Furthermore, PPARα activation increased PGE2 concentrations, suggesting a direct link between PPARα and the promotion of Coxiella survival. Conclusion Our study indicates that host PPARα initiates a suppressive immune response to support Coxiella infection. These findings identify host PPARs as potential therapeutic targets to inhibit Coxiella intracellular growth. Funding Source N/A Topic Categories Innate Immune Responses and Host Defense: Cellular Mechanisms (INC)

A Quinoidal J‐Aggregated Indacendiselenophene Exhibiting High Responsivity in Ultra‐Narrowband Organic Photodetection

ABSTRACT Organic semiconductors that exhibit narrowband absorption in the near‐infrared (NIR) region are highly sought after for photodetector applications, yet achieving such behavior intrinsically remains a considerable challenge. We report a novel fused quinoidal tetracyanoindacenodiselenophene material (QIDSe‐C16) that forms solid‐state J‐aggregates producing a remarkably sharp absorption band with a full width at half‐maximum (FWHM) of 27 nm centred at 772 nm, closely matching that of its sulfur analogue (QIDT‐C16). Despite exhibiting similar optical and electrochemical characteristics, selenium substitution enhances charge‐carrier mobility and significantly improves device performance. Optimized organic phototransistors (OPTs) based on QIDSe‐C16 display ambipolar transport and excellent photoresponsivity, reaching 289 A W −1 at 780 nm illumination, which is an order of magnitude higher than QIDT‐C16‐based devices and among the best so‐far reported values. Our findings demonstrate that controlling solid‐state aggregation through heteroatom engineering offers an effective route to narrowband, filter‐free NIR photodetectors that combine spectral selectivity with high charge transport.

A Xerotic Skin‐Compatible Neuromotor Electrode Interface for Non‐Invasive Muscle Weakness Evaluation in Dermatomyositis

ABSTRACT Dermatomyositis creates a clinical demand for non‐invasive, quantitative muscle weakness assessment, which can be achieved by decomposing neuromotor information from surface electromyography (sEMG). However, the absence of a stable electrode interface compatible with pathologically xerotic skin has hindered this approach. Here, we develop a conformable neuromotor electrode interface that overcomes this via molecular engineering, exhibiting an ultrasoft modulus (∼ 2.13 kPa), low impedance (∼ 0.9 kΩ at 1 kHz), and stable electrical retention over 7 days. This interface enables the acquisition of high‐fidelity sEMG from dermatomyositis patients with low baseline noise (< 2 µV root mean square) and high inter‐channel signal correlation, allowing robust decomposition of neuromotor biomarkers including motor unit count, action potential amplitude, and firing rate. Clinically, our multi‐biomarker quantification strategy shows strong agreement with gold standard assessments. Moreover, our approach can detect subtle interpatient variations like early recruitment patterns, enabling personalized treatment beyond the clinical gold standard. This work establishes a transformative platform for precise muscle weakness evaluation, overcoming the limitations of needle electromyography and subjective clinical scales.

Conformational dynamics of the membrane-anchored foldase LipH from Pseudomonas aeruginosa governs recognition and release of its client lipase

Efficient design of blockchain-based electronic health record systems with federated learning, off-chain storage, and zk-rollup parallelism for minimizing transaction costs

Moderating Regulatory T Cell Brakes in CAR T Cell Immunotherapy of Solid Tumors Through the CD4-CD28 Co-stimulation Axis 2260886

Abstract Introduction CAR-T cell immunotherapies are at the translational frontline for solid tumors. However, loss of T cell function over time, and the immunosuppressive tumor microenvironment (TME) limit the efficacy of cell therapies in solid tumors. Regulatory T cells (Treg) in the TME are key immunosuppressive mediators that derail therapeutic efficacy. However, in human clinical trials, severe systemic autoimmune toxicity remains a primary roadblock in clinical advancement of Treg-targeting immunotherapies for solid tumors. Here, we elucidate the mechanisms of Treg depletion mediated toxicity and identify key therapeutic interventions for translating balanced safety and efficacy of CAR T cell immunotherapy for solid tumors. Methods Towards developing strategies that remove Treg-mediated brakes on tumor-reactive T cells, while concurrently preventing autoimmune toxicity, we used immunocompetent murine models of CAR T cell therapy of syngeneic solid tumors ranging from “hot” (melanoma) to “cold” (neuroblastoma). Foxp3-DTR transgenic mice were engaged to achieve targeted Treg ablation using low dose diphtheria toxin administration. Results Our studies show that ablation of Tregs enhances tumor control by overcoming the brakes on anti-tumor effector cytotoxic T lymphocyte (CTL) program. Mechanistic studies establish that CD28-CD80/86 costimulation axis plays a dominant role in Treg-depletion toxicity. Paradoxically, blocking of CD4 T cell activation via CD28 causes a complete rescue of autoimmune toxicity, without compromising anti-tumor therapeutic efficacy and development of systemic memory CAR T cells in the peripheral lymphoid and non-lymphoid tissues for lifelong protection from tumor relapse. Furthermore, we show that Tregs exert the autoimmune toxicity almost entirely via the inhibitory receptor CTLA-4 expressed on Treg cells. Conclusion Our data lay the preclinical groundwork for translating Treg-ablation strategies during CAR T cell immunotherapy for safe and durable remission of solid tumors. Funding Source This study was funded by the National Institutes of Health (National Cancer Institute, and National Institute of Allergy Immunology and Infectious Diseases) and Pediatric Cancer Research Foundation. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Transcriptional regulation of CD91 expression in antigen presenting cells and its impact on immune responses and disease 2231601

Abstract Introduction Cancer immunosurveillance depends on elimination of emerging tumors by cytotoxic T cells. Priming of T cells relies on the delivery of 3 signals from antigen-presenting cells (APC) in the form of MHC-peptide complexes, co-stimulatory molecules, and cytokines. In cancer cells, tumor peptides are associated with HSPs. Upon release by necrotic cancer cells, HSPs are captured by CD91 and these peptide antigens are cross presented. CD91-mediated signaling networks are also initiated by HSP binding and activates DCs to provide co-stimulation and cytokines. Interestingly, variable CD91 expression levels on APCs in humans correlate with differential cancer outcomes and anti-tumor immune responses. While the functional importance of CD91 in disease is known, the transcriptional control of CD91 in APCs remains unclear and represents a potential mechanism to explain the variable expression. The objective of this work is to utilize in vitro genetic screens to identify factors controlling CD91 expression in APCs. We hypothesize that disruption of these factors will change CD91 expression and regulate CD91-dependent immune functions, including cancer immunosurveillance. Methods To identify transcription factors (TFs) regulating CD91 expression and validate direct transcriptional regulation, we will use an unbiased TF CRISPR screen, ChIP-PCR, select TF siRNA, and CD91-promoter driven luciferase reporter assays. Results We have identified candidate TFs using in silico transcription factor binding prediction analysis and will further screen with siRNA knockdown analysis. Conclusion Ultimately, this work aims to uncover novel transcriptional circuits controlling APC function. Translationally, these findings will inform rational design for dendritic cell-based therapies and identify druggable molecular targets for not only cancer, but also infectious, neurological, cardiovascular, and autoimmune diseases, where CD91 has been shown to play important roles. Funding Source NIH Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

S-4321 Is a Novel, Non-Depleting, Bifunctional PD-1:FcγRIIB Selective Agonist Antibody for the Treatment of Immune-Mediated Diseases 2333621

Abstract Introduction Inhibitory receptors upregulated on activated lymphocytes play a critical role in restoring and maintaining immune homeostasis to control autoimmunity. Strong PD-1 agonism requires super-clustering, which is achieved when antibodies bind to Fc gamma receptors (FcγR) on aAPCs. Several PD-1-targeted antibodies have been investigated in autoimmunity with mixed clinical results, however, rather than agonizing PD-1, these first-generation antibodies primarily deplete PD-1+ T cells, as demonstrated in human trials. S-4321 is a novel bifunctional antibody that agonizes PD-1 on T cells through a different binding site than its natural ligands, PD-L1 and PD-L2, while selectively engaging the inhibitory FcγRIIb on B cells and APCs. Therefore, by avoiding liabilities seen with first-generation PD-1 binders, such as Treg depletion and reduced PD-1 expression, S-4321 is expected to restore immune homeostasis in cell-mediated autoimmunity. Methods PD-1 and FcγRIIb agonism were assessed using in vitro functional assays and in vivo studies in naïve mice and a murine GvHD model. Results S-4321 achieves prolonged agonism by binding to PD-1 with low affinity, which preserves PD-1 expression on T cells, unlike first generation PD-1 depleters. S-4321 also selectively binds and signals through FcγRIIb, avoiding the induction of proinflammatory cytokines and undesirable depletion of PD-1+ T cells by ADCC. S-4321 reduces T cell expansion and proinflammatory cytokine production in a murine model of GvHD. Conclusion In contrast to first generation PD-1 depleters, treatment with S-4321 does not result in loss of PD-1 expression on T cells, induction of proinflammatory cytokines, or depletion of PD-1+ Tregs. By coupling PD-1 agonism with inhibitory FcγRIIb engagement, S-4321 has the potential to restore immune homeostasis in cell-mediated autoimmunity. A Phase 1 clinical study is ongoing to assess safety, tolerability, PK/PD and immunogenicity. Funding Source N/A Topic Categories Therapeutic Approaches to Autoimmunity (THER)

Identification of lncRNA VILMIR-protein interactions within the host interferon response 2257841

Abstract Introduction Long non-coding RNAs (lncRNAs) can play a major role in modulating innate immune responses by acting as positive or negative regulators. LncRNAs can mediate protein interactions with chromatin and other proteins by serving as scaffolds, decoys, and guides. The expression pattern of most lncRNAs is cell and context specific, making them attractive targets for precise therapeutic intervention. However, only a small number of lncRNAs have been well characterized due to their low abundance, context dependent expression, and complex modes of action. We have previously identified lncRNA VILMIR as an interferon-stimulated gene that regulates host interferon response to viral infection and interferon treatment. In this study, we investigated molecular mechanisms through which VILMIR modulates host immune response. Methods Using in vitro RNA pulldown assays followed by in vivo RNA immunoprecipitation validation, we identified several VILMIR-interacting proteins, including FUBP1, an RNA-binding protein implicated in transcriptional regulation. Mapping experiments with truncated VILMIR fragments revealed specific regions involved in protein binding. Results Our findings suggest that VILMIR modulates transcription of interferon-stimulated genes by forming an RNA-protein complex with FUBP1. Conclusion Future studies will focus on elucidating how the VILMIR-FUBP1 complex influences the transcriptional landscape during viral infection and exploring its potential as a therapeutic target to fine-tune antiviral immune responses. Funding Source National Institutes of Health Grant R21AI147187 Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)

Hyperglycemia-induced HIF-1α dysregulation drives epithelial barrier dysfunction and increases susceptibility to oral candidiasis 2245480

Abstract Introduction Diabetes increases susceptibility to infectious diseases, including oropharyngeal candidiasis (OPC, or thrush), an opportunistic infection caused by the commensal fungus Candida albicans. Individuals with poorly controlled diabetes exhibit a higher incidence and severity of OPC. Despite its clinical relevance, there are currently no targeted therapies for diabetic OPC, largely because the mechanisms by which hyperglycemia increase OPC susceptibility and alter oral mucosal immunity remain unknown. Methods Studies were conducted using hyperglycemic human oral epithelial cells, and physiological relevance was confirmed using streptozotocin-induced diabetic mouse models. Readouts including fungal burden, immune responses, and metabolite profiling were analyzed following C. albicans infection Results We identified that hyperglycemia enhances susceptibility to OPC by impairing hypoxia-inducible factor 1-alpha mediated epithelial barrier function and mucosal immunity during C. albicans infection. Mechanistically, hyperglycemia or HIF-1α knockdown suppressed claudin-1 expression, a tight junction protein regulated by HIF-1α, leading to epithelial barrier dysfunction. Additionally, hyperglycemia promoted epithelial pyroptosis, an inflammatory form of cell death, through HIF-1α-dependent activation of cleaved gasdermin D during infection. Furthermore, hyperglycemia induced dysregulated proline metabolism, characterized by elevated proline levels and reduced expression of proline dehydrogenase, which contributed to aberrant inflammation and impaired epithelial immunity during infection. Conclusion Our findings highlight the critical role of HIF-1α in regulating epithelial barrier integrity and pyroptosis, suggesting it as a potential therapeutic target for mucosal fungal infections in patients with diabetes. This work provides novel insights into host-pathogen interactions under hyperglycemic conditions and identifies potential targets for the management of diabetes-associated mucosal infections. Funding Source n/a Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Loss of HIV-1-specific neutralizing antibodies via Δ42PD-1 positive B cells 2333776

Abstract Introduction Δ42PD-1, an isoform of PD-1, abolishes PD-L1/PD-L2 binding and confers T cell resistance to anti-PD-1 immunotherapy. Δ42PD-1 modulates B cell function in people living with HIV (PLWH) through functional exhaustion, cell cycle arrest, and apoptosis. We then hypothesized that HIV-1-induced Δ42PD-1 affects the induction of broad neutralizing antibodies (bnAbs). Methods We analyzed primary B cells from nine PLWH, comprising three acute cases, three chronic untreated cases and three chronic cases on ART. Δ42PD-1+ and Δ42PD-1⁻ B cells, including Env-specific subsets by oligo-tagged BG505 SOSIP.664 (BG505), were sorted for 10x single-cell sequencing and functional analysis. Results A total of 22,999 B cells were sequenced, comprising 6,245 Δ42PD-1+ and 16,754 Δ42PD-1⁻ cells. Of these, 1,113 were BG505 reactive, including 820 Δ42PD-1+ cells and 293 Δ42PD-1⁻ cells, corresponding to overall frequencies of 13.1% (820/6,245) and 1.7% (293/16,754), respectively. Although overall B cell clonotype diversity was similar between the two groups, BG505 reactive heavy chains were predominantly encoded byIGHV4-34. Among 181 highly BG505 reactive B cell receptors cloned for functional analysis, 111 originated from the Δ42PD-1+ subset and 70 from the Δ42PD-1⁻ subset, with the majority recognizing gp41 (85.6% vs. 78.6%). Five bnAbs (2 from Δ42PD-1+ and 3 from Δ42PD-1⁻ cells) neutralized pseudoviruses from multiple HIV-1 subtypes. Their potency was associated with somatic hypermutation (SHM; range, 0.75—22.01%) and extended CDR3 regions (19—24 amino acids). Δ42PD-1+ B cells exhibited impaired SHM maturation and antibody secreting cell differentiation due to increased functional exhaustion and apoptosis. Conclusion Most HIV-1—activated B cells differentiate into the Δ42PD-1+ subset, leading to impaired maturation of neutralizing antibodies. Δ42PD-1 may serve as a therapeutic target for enhancing functional B cells for generating bnAbs. Funding Source RGC No. 17119723 Topic Categories Viral Immunology (VIR)

Conserved moonlighting protein pyruvate dehydrogenase induces robust protection against Staphylococcus aureus infection 2248909

Abstract Introduction Staphylococcus aureus is an opportunistic pathogen causing skin, soft tissue, and bloodstream infections, with high incidence in industrialized countries. Rising antibiotic resistance has complicated treatment as resistant strains spread beyond healthcare settings. Traditional vaccine targets include virulence factors such as ClfA and Hla. Recently, the lipoylated E2 subunit of pyruvate dehydrogenase (PDHC) from S. aureus was found to act as an immunosuppressant by blocking macrophage activation. Here, we show that immunization with PDHC confers robust protection against lethal S. aureus challenge in multiple animal models. Methods Recombinant PDHC was expressed in E. coli and purified via affinity chromatography. Mice and rabbits were immunized subcutaneously. Antibodies were detected by ELISA. Mice were challenged intravenously, intraperitoneally, or subcutaneously with S. aureus. RNA-seq and flow cytometry were used to assess immune responses. Results PDHC is > 99% conserved among S. aureus strains and elicits strong humoral and cellular immunity. Vaccination protected against methicillin-sensitive and -resistant strains in multiple murine models. Protection in bloodstream infection did not require antibodies; B cell-deficient mice showed enhanced proinflammatory chemokine expression, indicating reliance on cellular immunity. γδ T cells were essential for bacterial clearance via neutrophil and macrophage activation, with increased Granzyme B expression post-infection. PDHC remained effective in mice with prior S. aureus exposure and formed self-assembling nanoparticulate structures. In rabbits, PDHC reduced skin abscess formation. Conclusion PDHC is a highly conserved, serotype-independent vaccine candidate that induces γδ T cell—mediated systemic immunity and protects against diverse S. aureus strains, including MRSA, even in previously exposed hosts. Funding Source HMRF Topic Categories Vaccines and Immunotherapy (VAC)

Phenotypic and Metabolic Signatures in Chronic Autoimmune Inflammation 2308477

Abstract Introduction Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by systemic chronic inflammation that can lead to heterogeneous clinical manifestations, from mild cutaneous disease to multi-organ damage and failure. Understanding how immune cell composition, their activation status, and metabolic changes contribute to disease is important to identify new biomarkers and therapeutic targets. Methods In this study, we combined spectral flow cytometry and CITE-Seq to profile immune cell subsets and metabolic changes at the single-cell level. Peripheral white blood cells from SLE patients, psoriatic arthritis (PsA) patients, and healthy donors were analyzed using a 50-marker panel that evaluated immune subsets, activation and exhaustion markers, including metabolic dependencies by using SCENITH. The same antibody panel was used in CITE-Seq to validate flow cytometric findings and explore additional metabolic and inflammation pathways. High-dimensional computational analysis was used to identify immune subpopulations with specific metabolic signatures that distinguished SLE from PsA and healthy individuals. Results Across 44 immune cell populations, we observed significant immunophenotypic and immunometabolic changes in both diseases. B cell analysis revealed altered frequencies, different translational activity, and metabolic dependence in early developmental and antigen-experienced cell subsets. SCENITH profiling showed distinct metabolic signatures in CD4+ and CD8+ T cells, with more pronounced differences in naive and memory subsets. In fact, in SLE, T cells exhibited strong dependence on OXPHOS and limited sensitivity to glycolytic inhibition. Finally, PsA patients presented increased NKT-cell frequencies, indicating an involvement of lipid antigens. Conclusion Overall, these findings describe several immune and metabolic dysregulations in SLE and PsA patients, which could be used as potential biomarkers for disease progression and therapeutic intervention. Funding Source Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project 321115009 (GRK 2336/3) Topic Categories Basic Autoimmunity (BA)

A‐Site High‐Entropy Perovskite Enabling Sulfur‐Tolerant and Coking‐Resistant Anodes for Hydrocarbon‐Fueled Solid Oxide Fuel Cells

ABSTRACT Solid oxide fuel cells (SOFCs) are capable of electrochemically converting fossil fuels such as natural gas and coal‐based syngas directly into electricity with high efficiency and minimal emissions, yet the state‐of‐the‐art nickel‐based anodes are susceptible to sulfur poisoning or coking when operated with sulfur‐containing or hydrocarbon fuels. Here, we report a high‐entropy strategy in which five equimolar cations are introduced at the A‐site to develop a highly active and robust perovskite anode, Pr 0.2 Ba 0.2 La 0.2 Sr 0.2 Ca 0.2 FeO 3‐δ (PBLSCF). In situ reduction of PBLSCF leads to the exsolution of nanoscale Fe particles, enhancing its tolerance to sulfur poisoning and coking. Electrolyte‐supported single cells using PBLSCF anodes achieve a peak power density (PPD) of 1.22 W cm −2 at 800°C in H 2 , maintain stable operation for 1000 h and exhibit promising sulfur tolerance in 50 ppm H 2 S‐H 2 . Density functional theory (DFT) calculations reveal that the high‐entropy strategy reduces oxygen‐vacancy formation energy, contributing to improved sulfur tolerance and fuel oxidation performance. Furthermore, stable operation using a PBLSCF anode for 600 h is also achieved with propane as fuel. This work provides a synergistic strategy through A‐site high‐entropy engineering and in situ metal exsolution to achieve promising electrochemical performance and enhanced multi‐tolerance anodes for fuel‐flexible SOFCs.

Universal Phase Engineering of High‐Entropy Sulfides for Stable Sodium‐Ion Storage With Ultra‐High Capacity and Ultra‐Fast Kinetics

ABSTRACT High‐entropy transition metal sulfides (HESs) exhibit great potential as anodes for sodium‐ion batteries owing to their synergistic entropy stabilization, lattice distortion and cocktail effects. However, potential phase separation caused by multi‐component incompatibility severely limits their performance. Herein, we propose a low‐mixing‐enthalpy strategy through regulation of element chemical compatibility to precisely design high‐performance HES anodes. This strategy enables the successful synthesis of a single‐phase Co‐Fe‐Ni‐Mn‐Cr HES solid solution (HES‐Cr). In contrast, inferior compatibility among components in Co‐Fe‐Ni‐Mn‐Mo HES (HES‐Mo) leads to its phase separation. The electron delocalization in HES‐Cr enhances conductivity and metal‐sulfur bond covalency, while moderate lattice distortion alleviates volume changes and stress concentration during Na + insertion/extraction and lowers the Na + migration barrier. Consequently, the HES‐Cr delivers excellent Na + storage performance, including a high reversible capacity of 845.2 mAh g −1 at 0.2 A g −1 and ultra‐high rate property of 497.5 mAh g −1 even at 40.0 A g −1 along with long stability, outperforming HES‐Mo and most HES‐based anodes. Furthermore, we propose a three‐parameter descriptor to predict single‐phase high‐entropy materials across a broader compositional range. This work provides a new approach for rational design of single‐phase HESs and deepens understanding of their composition‐phase‐performance relationships.

Transcobalamin receptor CD320, responsible for vitamin B12 cellular uptake, is present on the cell surface as a homo-oligomer