Browse Articles

Single-cell Transcriptomics of the 13-lined Ground Squirrel Spleen Reveals a Shift to Energy-Conserved Immune Stasis During Torpor 2336515

Abstract Introduction Hibernating mammals undergo profound metabolic depression during torpor, severely constraining immune energetics. Although reversible leukopenia is well documented, how immune organization within secondary lymphoid organs adapts to this extreme state remains unclear. Methods We combined quantitative splenic histology with single-cell RNA sequencing to profile architectural and transcriptional remodeling in the spleen of 13-lined ground squirrels during torpor. Results Torpor induced selective architectural remodeling of the spleen, marked by contraction of white pulp regions without changes in overall organ size or mass. This was accompanied by an ∼52.4% reduction in the relative abundance of B cells and a proportional enrichment of innate immune populations, including macrophages and dendritic cells, indicating a shift in splenic immune composition during metabolic quiescence. Notably, these changes did not reflect passive immunosuppression. Instead, immune cells across lineages adopted transcriptional programs consistent with active regulation, including coordinated suppression of anabolic signaling, glycolysis, cell-cycle progression, antigen presentation, and effector pathways, alongside induction of stress-adaptive maintenance programs. Adaptive immune lineages responded divergently: B cells entered a restrained state linked to genomic integrity and long-term maintenance, whereas T cells remained numerically stable but shifted into a deeply quiescent, energy-minimal state. In contrast, innate immune cells–including macrophages, dendritic cells, and neutrophils–were retained in a subdued configuration compatible with tissue surveillance and rapid reactivation upon arousal. Conclusion Together, these findings show that torpor establishes a reversible, lineage-specific program of regulated immunological stasis within the spleen, redefining it from an activation hub into a preservation reservoir poised for rapid immune reactivation. Funding Source n/a Topic Categories Veterinary and Comparative Immunology (VET)

Investigating a potential protective role for a microbial metabolite in celiac disease pathogenesis 2267135

Abstract Introduction Patients with celiac disease (CD) are predisposed by the HLADQ2/DQ8 haplotypes, with 99% of patients possessing one or both of these alleles. 30-40% of the greater population expresses at least one of these alleles, however, only 1-2% of the population is diagnosed with CD. Genetics alone cannot explain the worldwide increase in CD incidence, strongly indicating that environmental factors are at play. One factor of interest is the gut microbiome. Methods We recently conducted a prospective cohort study using plasma and fecal samples from children aged 2.5 and 5 years collected before the onset of disease (CD progressors) from the prospective cohort All Babies in Southeast Sweden (ABIS) study and analyzed the plasma metabolome. We identified a microbial metabolite, taurodeoxycholic acid (TDCA) that was upregulated two-fold. We treated C57BL/B6 mice and DQ8-Dd-villin-IL15-tg mice with TDCA and performed histological analysis on small intestinal tissue and flow cytometry to examine the populations of immune cells present in the small intestines of these mice. Results When C57BL/B6 mice were treated with TDCA, it induced villous atrophy in the duodenum, upregulated CD4+ T-cells, and decreased T regulatory cells. The DQ8-Dd-villin-IL15-tg mice overexpress IL-15 in the lamina propria and possess the predisposing HLA-DQ8 allele. Treating these mice with TDCA (0.4%, n = 16/sex) caused changes in the morphology of the ileum, including a decrease in villous length as defined by a decrease in the villi/crypt ratio in mice on a gluten-free diet. However, mice that were fed a diet containing gluten paired with TDCA did not experience similar changes and also had reduced intraepithelial lymphocytes (IELs) and goblet cells compared to the gluten controls. Additionally, preliminary data suggests that these mice also have decreased numbers of T regulatory cells. Conclusion Our results indicate that TDCA might protect against villous atrophy when combined with gluten in the context of CD. Funding Source n/a Topic Categories Mucosal and Regional Immunology (MUC)

Fibrotic function of bystander-activated PD-1high CD4 T cells in pulmonary fibrosis 2309544

Abstract Introduction Conventional CD4 T cell activation requires antigen recognition through the T cell receptor along with co-stimulatory signals and cytokines. Recent studies have demonstrated that cytokine signaling alone can activate CD4 T cells without antigen recognition, called bystander activation, and these CD4 T cells contribute to various inflammatory diseases. However, whether these bystander activated CD4 T cells contribute to pulmonary fibrosis remains unclear. Methods In this study, we investigated the unique function of fibrotic CD4 T cells using bleomycin-induced lung fibrosis model and analysis of public single-cell and spatial RNA sequencing data from lung tissue of human IPF patients, and explored the underlying mechanisms. Results We identified a subpopulation of PD-1high CD4 T cells which are markedly increased in pulmonary fibrosis mouse model and in lung tissue from IPF patients. These cells mainly express IL-33 receptor and amphiregulin and their activation is independent of specific antigen. Notably, PD-1high CD4 T cells are already present in lung tissue of steady-state mice, increased with aging and respond selectively to IL-33 and IL-25 stimulation in the absence of TCR engagement. Single-cell RNA sequencing revealed that IL-33 and IL-25 stimulated CD4 T cells upregulate Th2-related cytokines and amphiregulin with Batf identified as a key transcriptional regulator of this bystander response. Batf deficiency and chemical inhibition of Batf significantly reduced bystander-activation of CD4 T cells by IL-33 and IL-25 stimulation and markedly attenuated pulmonary fibrosis pathology. Conclusion Taken together, these findings identify a unrecognized population of bystander-activated, profibrotic PD-1high CD4 T cells in both mice and humans and establish the Batf/amphiregulin axis in CD4 T cells as an important mediator of pulmonary fibrosis progression. Funding Source This research was supported by the Basic Science Research Program of the National Research Foundation funded by the Korean government (RS-2024-00334289). Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)

Discovery of immune biomarkers for detection of exposure to Anopheles stephensi, an invasive and highly competent Plasmodium falciparum malaria vector 2259616

Abstract Introduction The recent invasion of Anopheles stephensi (Ans), a highly competent, urbanized vector of Plasmodium, into Africa threatens malaria prevention efforts. Epidemiological studies are necessary to track the mosquitoes. Immunological biomarkers, such as antibody in human plasma targeting Ans-specific salivary antigens, could be the basis of serologic screening assays indicating the invasive mosquito’s presence and impact on local transmission. These antigens have been used to search for serological biomarkers of mosquito exposure, but the use of shorter peptides allows non-conserved epitopes to be targeted. Methods Plasma from a US-based controlled human malaria infection study, where participants were exposed to repeated Ans bites, and Ans-naïve Malian children were tested on an overlapping peptide microarray with single-amino acid resolution. The microarray included six Ans salivary antigens (ce5, D7, SG1b, SG5, SG6, Trio). Maximum median fluorescence intensity for sequential 10-mers peptides across each protein was used to construct receiver operator characteristic (ROC) curves to determine each peptide’s utility in distinguishing Ans-exposed from Ans-naïve plasma. Results Three 10-mers with the highest area under the ROC curve (AUC) were selected. D7290-314, D7182-206, and SG5309-333 and yielded AUCs of 0.77, 0.69, and 0.57, respectively. Using the highest MFI for any peptide among these three as the true signal for each sample yielded an AUC of 0.89. Sequence analysis of each peptide and the surrounding regions confirmed that two (SG5309-333 and D7182-206) are divergent from major African malaria vectors. The third peptide, D7290-314, is much more conserved but differs in two potentially crucial loci. Conclusion Sequence homology among Anopheles proteins makes a peptide-level search for serological biomarkers essential. Three peptides from the D7 and SG5 salivary gland antigens are strong candidates for serological assays to monitor Ans range and exposure. Funding Source National Institutes of Health Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

A Novel Mediator Extracellular Caspase-1 Worsens Acute Lung Injury in Sepsis 2257697

Abstract Introduction Sepsis is a severe systemic inflammatory condition. Over half of the septic patients develop acute lung injury (ALI), worsening mortality. Inflammasome activation triggers procaspase-1 cleavage to active Caspase-1 (p10/p20 tetramer), which then cleaves GSDMD, forming membrane pores for the release of DAMPs. We hypothesize that Caspase-1 is released via GSDMD pores, and extracellular Caspase-1 (eCasp-1) exacerbates ALI in sepsis. Methods Plasma from surgical intensive care unit patients and healthy controls was analyzed for eCasp-1 by ELISA. Sepsis was induced in mice by cecal ligation and puncture, and their plasma was assessed for eCasp-1. Murine peritoneal macrophages were treated with LPS+Nigerecin ± GSDMD inhibitor disulfiram, and eCasp-1 levels were assessed. The eCasp-1/TLR4 interaction was assessed by BIAcore, and the TLR4-mediated effects of eCasp-1 were evaluated using TLR4-/- mice. A small peptide, C16, was developed to interrupt eCasp-1/TLR4 interaction, and its therapeutic effects on ALI were evaluated in septic mice. Results We discovered that the p20 subunit of Caspase-1 (termed eCasp-1) significantly increased in the blood of patients and septic mice but is undetectable in healthy controls or sham mice. We determined that eCasp-1 is released via GSDMD pores. We identified a strong affinity between eCasp-1 and TLR4, demonstrating that eCasp-1-induced inflammation occurs via TLR4. eCasp-1 administration (i.p.) significantly increased systemic inflammatory and organ injury markers in WT mice. These effects were significantly reduced in TLR4-/- mice. In septic mice, C16 treatment significantly decreased blood injury and inflammatory markers, reduced lung chemokine/cytokine expression, and decreased histologic lung injury. C16 treatment significantly improved the survival rate in sepsis from 40% to 80%. Conclusion eCasp-1 is a novel DAMP that exacerbates ALI in sepsis. Targeting eCasp-1 with C16 attenuates ALI and improves survival, suggesting a novel therapeutic approach for sepsis. Funding Source National Institutes of Health (NIH) grants R35GM118337, and R01HL076179 Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)

High-Throughput Multiplexed Single-Cell Analysis Using Protein Barcoding with Pacific Blue and DyLight800 2306498

Abstract Introduction High-throughput single-cell analysis requires strategies that minimize reagent use while enabling multiplexed detection of intracellular targets. Protein barcoding using spectrally distinct dyes offers a scalable approach to simultaneously analyze multiple samples under identical staining conditions. Here, we describe a workflow employing Pacific Blue and DyLight800 dyes for barcoding fixed and permeabilized cells, enabling multiplexed immunostaining and spectral unmixing on the CytoFLEX mosaic Spectral Detection module. Methods Cells were treated, fixed, and permeabilized prior to barcoding with 16 unique dye combinations of Pacific Blue and DyLight800. Barcoded samples were pooled and stained with antibodies targeting phosphorylated nuclear proteins conjugated to PE and APC. Enhanced green fluorescent protein (eGFP) transfection served as a reporter for transfection efficiency. Data acquisition was performed using the CytoFLEX mosaic Spectral Detection module, followed by computational unmixing and gating to resolve individual barcoded populations. Results Spectral profiles confirmed distinct intensity signatures for each barcoded combination, allowing accurate discrimination of up to 16 samples per well. Integration with plate-based workflows enabled processing of 1,536 samples per plate. Barcoding did not interfere with antibody binding or eGFP detection Conclusion Multiplexed analysis revealed consistent staining patterns across pooled samples, validating the approach for high-throughput intracellular signaling studies. Funding Source n/a Topic Categories Technological Innovations in Immunology (TECH)

Reverse Epitope Discovery of Asparaginase-Specific TCRs and Their Target Epitopes 2267584

Abstract Introduction Asparaginase (ASNase) is a crucial component of pediatric acute lymphoblastic leukemia (ALL) combination chemotherapy. However, its use is complicated by hypersensitivity reactions that necessitate switching from Escherichia coli-derived ASNase to Erwinia chrysanthemi ASNase to maintain therapy. While most hypersensitivity cases can be avoided by switching formulations, a subset of patients develop allergic responses to both. The role of ASNase-specific T cell responses in the development of ASNase hypersensitivity is poorly defined, and no bona fide ASNase-specific T cell receptors (TCR) have been identified. Methods We analyzed a large bulk TCR sequencing dataset of ALL patients with and without ASNase allergy and identified single chains significantly associated with allergy. To identify paired TCRs specific for ASNase, we deployed a novel, high-throughput, paired TCR sequencing method (TIRTL-Seq) on additional ALL patient samples with allergy and compared sequence features to the allergy-associated single chains. Results This yielded a list of candidate paired TCRs, 8 of which have been stably transduced into reporter cell lines for use in peptide library screens to validate their specificity and characterize their epitope recognition. Conclusion Understanding the T cell responses in ASNase hypersensitivity will provide insight into drug induced allergic responses and lay the foundation for optimization of ASNase formulations with reduced immunogenicity. Funding Source St. Jude Graduate School of Biomedical Sciences Topic Categories Translational and Interventional Immunology (TI)

Size‐Dependent Trade‐off between Sulfur Catalysis and Sulfide Electrolyte Decomposition for Room‐Temperature Ultrahigh‐Rate All‐Solid‐State Li–S Batteries

ABSTRACT All‐solid‐state lithium‐sulfur batteries (ASSLSBs) hold immense promise for next‐generation safe and high‐energy storage, yet their power capability is fundamentally limited by sluggish solid‐state sulfur redox kinetics. While catalysis is effective in accelerating these reactions, we reveal for the first time that under overlapping potentials, such catalytic acceleration inevitably triggers severe parasitic decomposition of sulfide solid‐state electrolytes (SSEs), a critical yet overlooked bottleneck that disrupts Li + transport and limits high‐rate performance. To decouple efficient sulfur conversion from interfacial degradation, we devise a spatially selective catalyst architecture. Precisely sized cobalt clusters are confined within an ultra‐microporous carbon host. This design ensures intimate sulfur‐catalyst contact for rapid conversion while physically isolating the catalytic surfaces from the bulk SSE, thereby suppressing its catalytic decomposition. Consequently, the continuous Li + transport network is preserved. The resulting ASSLSB achieves an unprecedented room‐temperature rate capability, stably cycling at an ultrahigh current density of 25.0 mA cm −2 (15 C) for over 15,000 cycles. This work provides a general design principle for reconciling catalysis with interfacial stability in high‐power solid‐state batteries.

Bias‐Triggered Conductivity Relaxation (BCR): A Unique Tool to Simultaneously Investigate Thermodynamics, Kinetics, and Electrostatic Effects of Oxygen Reactions in MIEC Thin Films

ABSTRACT Mixed ionic‐electronic transfer (MIET) reactions, such as the oxygen reduction reaction (ORR) at oxide surfaces, are of paramount importance to manifold technologically highly relevant processes, and fundamental understanding must be developed to improve performance and tailor highly efficient electrodes and catalysts. Understanding such complex multi‐step reactions requires the study of kinetic processes, underlying thermodynamic properties, i.e., ionic and electronic defect concentrations, and electrostatic surface effects. However, conventional techniques struggle to uncover the complete picture within the same sample/measurement. Here, we overcome this limitation by introducing bias‐triggered conductivity relaxation (BCR) as a novel tool to investigate MIET reactions on oxides. It is based on alternating out‐of‐plane coulometric titration/polarization and in‐plane electrical conductivity relaxation measurements, providing simultaneous electronic, ionic, and extraordinarily rich surface kinetics information. This innovative combination of electrical and chemical driving forces synergizes information depth, with enhanced time resolution, versatility, and speed, yet it lifts the weaknesses of the individual approaches, while remaining cost‐effective and surprisingly simple. Furthermore, BCR allows to disentangle overpotential induced electrostatic modifications of the surface kinetics in a unique manner. We showcase the advantages of BCR in this work by studying the ORR in model (La, Sr)FeO 3‐δ thin film electrodes and reporting on their thermodynamic and kinetic properties.

Integrative multi-cohort bioinformatics and machine learning analysis reveals dysregulation of pro-inflammatory and pro-resolving lipid mediator pathway genes in atherosclerosis

Integrative Multi-omics Reveals Myeloid Signatures of Neoadjuvant Chemotherapy Response in Pancreatic Ductal Adenocarcinoma (PDAC) 2254994

Abstract Introduction Immune components, such as myeloid cells, including tumor-associated macrophages (TAMs), comprise a functionally diverse compartment of the PDAC tumor microenvironment capable of exerting both pro-tumorigenic and antitumor effects in response to microenvironmental cues. TAMs in solid tumors, including PDAC, are often considered to be immunosuppressive. However, due to their plasticity, they can aid anti-tumor immune responses. Among these TAM subsets, lipid-associated macrophages (LAMs) have recently emerged as a population enriched in lipid metabolism and phagocytic pathways. While some studies have used scRNA-seq and ATAC-Seq to identify distinct immune cell subsets in PDAC, none have focused on disparate chemotherapy responses in human PDAC. Thus, we performed multiomics sequencing to assess the transcriptomic and epigenomic landscape of PDAC tumors from patients who received neoadjuvant chemotherapy. Methods PDAC tissue samples from responders and non-responders were obtained from the WVU BIOTRAC Core upon surgical resection. Libraries for snMultiome + ATAC were prepared (10x Genomics) and sequenced by an Illumina sequencer. We performed single-cell annotation of major lineages, differential expression, and chromVAR TF-motif analysis. Results The cellular heterogeneity of the PDAC TME reveals distinct differences in the cell-type composition between the chemotherapy responders and non-responders. Responders showed an elevated lipid-associated macrophage (LAMs) population (38.4%) compared to non-responders (26.7%). Differential gene expression and enrichment analyses in responders’ myeloid cells highlighted phagocytosis and antigen presentation, suggesting functional reprogramming toward immune activation. Conclusion Neoadjuvant-treated PDAC tumors from responders exhibit a distinct myeloid landscape with enrichment of LAMs and immune-activating transcriptional/epigenetic programs, supporting a model in which immunometabolic reprogramming of myeloid cells contributes to therapeutic efficacy. Funding Source National Institute of General Medical Sciences, American Cancer Society, West Virginia Clinical and Translational Medicine, National Cancer Institute, and Hirshberg Foundation for Pancreatic Cancer Research Topic Categories Computational and Systems Immunology (COMP)

Investigating the immune response of male and female TLR-7 Knockout and Wild-type against inhaled Aspergillus fumigatus 2335288

Abstract Introduction A. fumigatus is a common opportunistic airborne fungus that poses significant health risks, especially for those with pre-existing allergic respiratory illnesses and those that are immunocompromised. Toll Like Receptor (TLR)-7 is important for the activation of the innate immune response; however, there is little knowledge against A. fumigatus regarding this receptor. Wild-type or TLR-7 deficient male and female mice and were exposed to airborne A. fumigatus spores. Bronchoalveolar lavage cells were collected; collagen and mucus were assessed using histological staining. Data was collected from naïve mice and mice at day 1 and day 14 post-exposure. Mucus and collagen levels had increased by day 1 post exposure and did not return to baseline till day 14 post exposure. TLR-7 knockout mice had higher levels of Macrophages, Neutrophils, and Eosinophils. Females had higher level of immune cells and IgE antibody levels overall. The results of this study will inform fungal disease modeling in mice and can help design better therapeutics and diagnostics for future reference. Methods Wild-type or TLR-7 deficient male and female mice and were exposed to airborne A. fumigatus spores. Bronchoalveolar lavage cells were collected; collagen and mucus were assessed using histological staining. Data was collected from naïve mice and mice at day 1 and day 14 post-exposure. Results Mucus and collagen levels had increased by day 1 post exposure and did not return to baseline till day 14 post exposure. TLR-7 knockout mice had higher levels of Macrophages, Neutrophils, and Eosinophils. Females had higher level of immune cells and IgE antibody levels overall. Conclusion The results of this study will inform fungal disease modeling in mice and can help design better therapeutics and diagnostics for future reference. Funding Source Undergraduate Student Research program, the Student Activity Fee Allocation Committee, the College of Science, Health, and the Environment, and the Judith Strong Foundation at Minnesota State University Moorhead Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)

What T cells see in B cells: Defining the immunopeptidome of germinal center B cells 2265788

Abstract Introduction Vaccine-induced germinal center reactions (GC) contain many B and T cells that display little measurable affinity for the immunogen, which is perplexing in late-stage GC reactions, when the quality of serum antibodies measured in the blood increases over time. I aim to addresses this disconnect by defining what T cells ‘see’ on B cells, by profiling the MHCII immunopeptidome of GC B cells. Methods This approach combines molecular immunology with mass spectrometry to profile what peptides are being presented on MHCII. Antibodies that recognize peptide-MHCII enable us to profile diverse antigens being presented overtime. Along with this, we will use pan-MHCII antibodies to pull down complexes, allowing mass spectrometric analysis of eluted peptide fractions. This can then be mapped back to their parental proteins to reconstruct the antigenic landscape available to T cells. Results I predict that late GC B cells will present a distinct catalogue of peptides, derived from many self-derived sources than early GC cells. This evolving peptide landscape may shape the ratio of helper and regulatory T cell interactions that GC B cells engage in over time, thereby influencing their selection. Conclusion This study will create the first longitudinal map of the GC B cell MHC-II immunopeptidome, showing how self-peptide presentation can shape the T cell compartment in the GC. Outcomes of this project will illuminate the black box of the GC and establish generalizable tools for the broader immunology community. Funding Source N/A Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)

DNA-PKcs regulates type I interferon responses in macrophages during bacterial infection 2334790

Abstract Introduction Macrophages, first responders to bacterial infection, integrate pattern recognition receptor (PRR) and interferon signaling to induce the production of reactive oxygen and nitrogen intermediates, which destroy intracellular bacteria. We have previously demonstrated that these genotoxic intermediates also damage macrophage genomic DNA, activating a DNA damage response (DDR) that is coordinated by kinases ATM and DNA-PKcs. This DDR modulates macrophage transcriptional responses during the innate immune response to infection. Though ATM has an established role in regulating cell-type-specific immune responses downstream of DNA damage, a potential role for DNA-PKcs in this regard has not been well-characterized. Thus, we asked whether or not DNA-PKcs regulates macrophage transcriptional responses during bacterial infection. Methods We compared the transcriptomes of wildtype and DNA-PKcs-deficient macrophages, after exposure to bacterial stimuli, using bulk RNA-sequencing. We also compared the transcriptomes of activated macrophages that were treated with a small molecule inhibitor of DNA-PKcs, AZD7648, relative to vehicle-only controls. Among the aforementioned experimental conditions, we assessed expression of a cohort of pro-inflammatory mediators using quantitative real-time PCR and ELISA. We also addressed relative activation of PRR- and interferon-regulated signaling cascades, among our experimental conditions, using immunoblotting. Results We find that DNA-PKcs signaling modulates the macrophage transcriptome of activated macrophages. Additionally, DNA-PKcs kinase activity is required for optimal STING-dependent and -independent type I interferon production in activated macrophages. Of note, we find reduced expression of some, but not all, interferon-stimulated genes (ISGs) in macrophages in which DNA-PKcs kinase activity is abrogated. Conclusion Taken together, these data suggest a potential role for DNA-PKcs in modulating ISG expression beyond its regulation of type I interferon production. Funding Source National Institutes of Health (1R16GM159931-01) Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)

Copper Shapes T Cell Metabolism and Epigenetics to Drive Pathogenic Th17 Cell Function in Autoimmunity 2259915

Abstract Introduction Pathogenic T helper 17 (pTh17) cells are a subset of CD4+ T cells driving autoimmune diseases including multiple sclerosis (MS). Methods To identify transporters controlling pTh17 cells, we conducted an in vivo shRNA-based forward genetic screen using the experimental autoimmune encephalomyelitis (EAE) model of MS. Copper Transporter 1 (CTR1), essential for copper uptake, emerged as a key regulator of pTh17 cell differentiation and function. Copper supports different cellular processes including mitochondrial metabolism and reactive oxygen species (ROS) balance. Results Deletion of CTR1 in CD4 T cells decreased intracellular copper levels, disrupting mitochondrial respiration and rewiring metabolism. These changes disrupted the epigenetic landscape of pTh17 cells by inducing DNA hypermethylation and altered chromatin accessibility, impairing transcription factor binding. As a result, CTR1-deficient T cells showed defective differentiation into pTh17 cells, with decreased production of IL-17A and expression of Th17 signature genes, while differentiation of other CD4 subsets remained unaffected. Moreover, T cell-specific deletion of CTR1 protected mice from EAE by suppressing clonal expansion of autoreactive CD4+ T cells and CNS inflammation. Conclusion These findings establish copper as a critical regulator of pTh17 differentiation and function, revealing a previously unknown molecular link between copper homeostasis, metabolism and epigenetic regulation governing Th17-mediated autoimmunity. Funding Source Colton Autoimmunity Center Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)

Tregs Require ABCB7 for their Development and Stability 2258259

Abstract Introduction The mitochondrial transporter ABCB7 is essential for exporting iron-sulfur (Fe-S) clusters, a function known to be critical in B cells. This study was conducted to investigate the broader, previously unknown roles of ABCB7 in regulating the overall lymphocyte development and homeostasis. Methods The study utilized conditional knockout (cKO) mouse models (CD2-iCre and Mb1-Cre) to create a specific deficiency of ABCB7 in certain immune populations. To determine if the observed effects were due to ABCB7 deletion in myeloid cells, two further models (CD2i-Cre ABCB7 cKO/C/EBPα and CD2-iCre LSL TMT ABCB7 cKO) were developed. The effects of blocking the cytokine G-CSF were also examined to understand its role in the observed myelopoiesis. Results ABCB7 deficiency was found to dramatically impair erythropoiesis while simultaneously driving emergency myelopoiesis. We confirmed that the myeloid expansion was not a direct result of ABCB7 loss in myeloid cells. A significant autoimmune phenotype also developed, characterized by hyperactivated T cells and a sharp decrease in peripheral regulatory T cells (Tregs). This Treg instability was linked to decreased thymic expression of key stability genes (like CD28 and PD-1) and reduced O-GlcNAc modification in T cells, a process crucial for maintaining Treg lineage. Conclusion The findings establish ABCB7 as a pivotal regulator of hematopoietic balance, linking mitochondrial function to both myeloid expansion and Treg stability. Funding Source T32AI170478 Topic Categories Hematopoiesis and Immune System Development (HEM)

A primordial variable lymphocyte receptor-like gene expressed in T-like lymphocytes of jawless vertebrates 2307608

Abstract Introduction Understanding the evolution of vertebrate adaptive immunity requires comparative analyses of anticipatory antigen receptors. Jawed vertebrates (gnathostomes) use immunoglobulin-based receptors generated by V(D)J recombination, whereas jawless vertebrates (agnathans), lampreys and hagfish, use variable lymphocyte receptors (VLRs) assembled from leucine-rich repeat (LRR) cassettes. Canonical germline VLR genes are incomplete, encoding invariant N- and C-terminal regions separated by noncoding intervening segments, and the evolutionary origin of this anticipatory system remains unresolved. Methods We analyzed lamprey and hagfish genomes to identify intact VLR-like genes and characterized their genomic context and phylogenetic relationships. Single-cell transcriptomics and quantitative PCR were used to define cell-type and tissue expression patterns. Structural modelling was used to predict the overall fold, LRR composition, and C-terminal stalk features of the encoded receptor. Results We discovered a primordial VLR-like gene (priVLR) in both lampreys and hagfish. Structural models indicate that the translated priVLR sequence adopts the characteristic VLR solenoid architecture with an extended LRRCT loop. Unlike canonical germline VLR loci, priVLR lacks noncoding intervening segments. Similar to VLRB, priVLR possess a predicted GPI-cleavage site in its C-terminal stalk and clusters phylogenetically with VLRB. However, single-cell transcriptomic analyses show that, in contrast to VLRB expression in B-like cells, priVLR is predominantly expressed in T-like lymphocyte populations in both species. Conclusion Characteristics of priVLR suggest that it may derive from an ancestral intact LRR genes that later gave rise to the more complex diversifying VLR isotypes that underpin antigen recognition in agnathans. Understanding the function of the priVLR protein in agnathan T-like lymphocytes has the potential to provide new insight into the origin of the agnathan adaptive immune system. Funding Source National Institutes of Health Grants R01AI072435, R35GM122591 Topic Categories Veterinary and Comparative Immunology (VET)

Discovering Shared Mechanisms of Autoimmunity using Omics Technologies 2259933

Abstract Introduction Autoimmunity is defined by disruption of the immune system, where instead of defending the body, the immune system turns on itself and attacks its own organs instead. While this immune dysfunction connects autoimmune diseases, each disease is distinguished by the organs involved and clinical features that characterize its presentation. The goals of this study are to utilize single-cell sequencing technologies to characterize peripheral immune cells and identify shared and unique mechanisms of autoimmunity. Methods To typify shared mechanisms of autoimmunity, samples were obtained across healthy controls and multiple diseases: Lupus, RA, IgG4-RD, Graves’ Disease, Hashimoto’s Disease, MS, T1D, Celiac Disease and ICI-related diabetes and thyroiditis. PBMCs were used to generate scRNAseq and paired protein data (10x Genomics). In-house data and multiple external data sets were aligned to the same genome and integrated (Harmony). Iterative clustering was used to distinguish cell subsets. Further downstream analysis includes abundance, differentially expressed gene analysis, and identification of cellular and transcriptional programs. Results Using the above pipeline we characterized 3.5M peripheral immune cells and identified 45 unique cell subsets. We are able to both redemonstrate known biology such as CD4+ lymphopenia across multiple autoimmune diseases, and highlight novel disease-specific findings such as monocyte subset expansion with interferon signature in a subset of diseases. The single-cell data also enables mapping the cellular context of autoimmune disease GWAS susceptibility variants, furthering our understanding of disease pathogenesis. Conclusion Our initial results demonstrate that autoimmune diseases have shared mechanisms that broadly propagate autoimmunity and unique transcriptional mechanisms that can drive specific disease states. Further definition of these shared and unique pathways can lead to the discovery of cross-disease and disease-specific therapeutic targets. Funding Source CZI, NIH, LRA, Breakthrough T1D, NMSS, Manton Foundation, Melanoma Research Alliance, Damon Runyon Cancer Foundation, Schmidt Futures, Broad Institute, MGH Topic Categories Immune Mechanisms of Human Disease (HUM)

Confined Reconstruction of Thiospinels Toward Stable Li–CO ₂ Batteries

ABSTRACT Oxidative reconstruction of thiospinel catalysts is well recognized as a common phenomenon in Li–CO 2 batteries, and the oxidation state of catalysts after reconstruction is known to be decisive for battery performance. However, the underlying mechanism of this correlation remains unclear, making it challenging to achieve a thiospinel catalysts that are active and invulnerable to restructuring in Li–CO 2 batteries. Here, the confined reconstruction of NiCo 2 S 4 during battery operation is achieved via a mild oxidation strategy and the mechanism for the improved durability is revealed. Operando X‐ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations reveal that the oxygen substitution creates a mixed O/S coordination environment for metal atoms (Co and Ni) in NiCo 2 S 4 and larger metal‐sulfur bond energy. The resulting strong metal‐sulfur interaction can stabilize the sulfur atoms and thereby enhance the structural durability against the oxidative reconstruction. Thus, the mild oxidation affords NiCo 2 S 4 cathode possessing excellent catalytic activities (high discharge capacity of 6906.8 µA h cm −2 ) and activity retention for over 2000 h. The mild oxidation principles proposed here provide a generalizable strategy for the design of stable electrocatalyst materials.

Deciphering the Catalytic Mechanism of Oxidoreductase‐Like Nanozymes Along the Reaction Pathway: Activity, Specificity and Sustainability

ABSTRACT As the most applied nanozymes, the catalytic mechanism of oxidoreductase (OR)‐like nanomaterials has received widespread attention over the past decades. Despite of the large efforts, their catalytic mechanism is currently abundant but still complicated, which restricts further development. Rather than the common mechanistic discussion simply classified by material type or regulatory method, this review deepens the analysis on the catalytic mechanism of OR‐like nanozymes through a detailed overview along their reaction pathways. The electron transfer sequence, substrate adsorption, reactive intermediate generation/transformation, and product desorption in the catalytic pathway of OR‐like nanozymes are explicitly investigated and compared with their natural counterparts. The root causes that determine their catalytic activity, specificity, and sustainability are highlighted. Moreover, the superiority of the catalytic mechanism‐tailored OR‐like nanozymes in various applications is highlighted. Finally, the future prospects of catalytic mechanism research are outlined, providing inspiration for the catalytic pathway clarification, activity improvement, specificity exploration, mechanism study at actual scenarios, and machine learning integration. It is anticipated that this review will promote a thorough and consistent understanding on the catalytic mechanism of OR‐like nanozymes.