Browse Articles

Identification of human T-cell cytomegalovirus epitopes and their conservation across the herpes virus family 2310276

Abstract Introduction Cytomegalovirus (CMV) is a leading cause of congenital birth defects and has a substantial clinical impact on a significant proportion of the U.S. population. To date, no approved vaccines are available to prevent congenital CMV infection in humans. Our study aimed to delineate specific immunogenic regions within each ORF through peptide deconvolution. Methods In a cohort of 27 CMV-positive donors, we examined T-cell memory responses across a set of 31 open reading frames (ORFs). We synthesized 15-mer peptides to prepare specific pools and megapools (MP) to detect T-cell responses and epitope identification. CD4 and CD8 T-cell responses were detected by activation-induced cell marker (AIM) assay. Results Our study established recognition of a set of CMV potential vaccine candidates for human CD4 and CD8 T-cell responses. Our results showed vigorous poly-antigenic responses of CMV ORFs varying in their CD4+ and CD8+ reactivity. A total of 552 different epitopes (458 CD4 epitopes and 94 CD8 epitopes) were identified. Of those, 66 CD4 epitopes and 36 CD8 epitopes were recognized in 3 or more donors. Correlation between regions containing CD4 and CD8 epitopes indicates that immunogens targeting both CD4 and CD8 responses can be designed. Antigen and epitope sequences are well conserved in human CMV strains (HCMV), but poorly conserved in other beta herpesviruses. The overall CD4/CD8 activity is correlated to IgG titers that are specific to pre- and post-fusion glycoprotein (gB). We have selected epitopes from ORFs associated with significant positive associations with IgG titers. Our proposed vaccine construct contained murine epitopes to assess for immunogenicity in mice for T-cells and antibody response enhancement. Conclusion Our study identified of a set of CMV regions eliciting human CD4/CD8 memory responses and IgG responses derived from a wide breadth of different antigenic targets. These regions could be combined to elicit robust humoral and T-cell responses targeting human CMV. Funding Source Advanced Research Projects Agency for Health (ARPA-H) Topic Categories Vaccines and Immunotherapy (VAC)

Short PDE4D isoforms potentiate pathologic Th17 function and mark arthritis-adapted memory CD4 T cells 2255274

Abstract Introduction Pathologic programs of human Th17 cells remain incompletely defined. Profiling memory CD4+ T cells from healthy controls (HC) and patients with psoriasis (PS), rheumatoid arthritis (RA), and ankylosing spondylitis (AS), we identified a PDE4D hi Th17 subset (P_Th17) whose features suggested arthritis-predominant biology and potential antigenic convergence. Methods We performed 5’ scRNA-seq with paired scTCR-seq on magnetic bead—sorted memory CD4+ T cells from 64 donors (HC, PS, RA, AS; n = 16 each). Condition-enriched states were mapped by unsupervised clustering, MiloR neighborhood testing, and cNMF program analysis. PDE4D isoforms were quantified with our pipeline. Synovial fluid/tissue (including spatial) datasets were analyzed to localize disease signals. Gain-of-function was tested by overexpressing short PDE4D isoforms (PDE4D1/2) in human memory CD4+ T cells. Results P_Th17 were increased in disease, with an AP-1—high subset specifically elevated in RA/AS. In patient synovial fluid, polyfunctional Th17 also exhibited high PDE4D. Isoform-resolved analysis showed selective upregulation of short isoforms (PDE4D1/2) within P_Th17; not all isoforms rose. The pathologic Th17 NMF program correlated strongly with short-isoform burden. TCR repertoire analysis revealed focused clonal expansions and shared CDR3β motifs within P_Th17, indicating antigen-driven selection consistent with tissue specificity. Upon anti-CD3/CD28 stimulation, Th17 cells with high P_Th17 features increased at the RNA level. Overexpression of PDE4D1/2 in human memory CD4 T cells enhanced activation and polyfunctional cytokine potential, supporting a short-isoform—dependent mechanism. Conclusion Arthritis is marked by a PDE4Dhi, AP-1—linked Th17 state with short-isoform dependency that aligns with polyfunctional Th17 signatures in inflamed synovium. Isoform-specific PDE4D regulation and arthritis-specific P_Th17 markers emerge as actionable axes for mechanistic dissection and therapeutic targeting. Funding Source n/a Topic Categories Immune Mechanisms of Human Disease (HUM)

Adaptive Immune Receptor Repertoire Knowledge Commons: data harmonization 2309859

Abstract Introduction Building a knowledgebase that integrates multiple data repositories requires the concepts, relationships, and data schemas/formats to be harmonized across those repositories. One technique is designing a common data model (CDM) that encompasses all concepts and relationships, transforming the data into the CDM, and utilizing ontologies to provide shared semantics. Methods The Adaptive Immune Receptor Repertoire Knowledge Commons (AKC) is a publicly accessible repository that integrates data and knowledge about 1) adaptive immune receptors (AIRs) and AIR repertoires from the AIRR Data Commons, 2) AIR germline allele, genotype, haplotype, and population genetic data from the OGRDB and VDJbase, and 3) AIR specificity data from the IEDB and IRAD. We designed a CDM for the AKC based upon the Ontology for Biomedical Investigations, a community standard for scientific data integration, and we used the LinkML data modeling language for implementation. Results The AKC provides a consistent CDM for study, subject, and sample information; immune exposures and other study events; sample collection; assays and processing; and data processing and analysis workflows. The CDM also provides adaptive immunity domain knowledge for chains, receptors, antigens, epitopes, and MHC/HLA. LinkML’s flexible data modeling language allows for existing data standards, such as the AIRR Standards, and ontologies from the OBO Foundry to be directly incorporated. Conclusion The foundation of the AKC is data integrated from these community-supported repositories and harmonized around a CDM based on widely adopted ontologies and data standards. The AKC assembles the critical mass of data required to develop highly accurate predictive algorithms for long-standing questions of critical importance (e.g., predicting AIR specificity, determining the contribution of AIR germline polymorphisms to disease propensity) and to ask questions across a large and diverse set of subjects with a variety of health and disease phenotypes. Funding Source The research described is supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under award number U24AI177622. Topic Categories Computational and Systems Immunology (COMP)

Porosity Engineering Within Ni─N─C Hollow Spheres for Ampere‐Level CO ₂ Reduction Electrocatalysis

ABSTRACT CO 2 electroreduction typically requires large overpotentials to sustain high reaction rates, which at current densities approaching 1 A cm −2 inevitably intensify competition from the hydrogen evolution reaction (HER), making it difficult to simultaneously sustain high product selectivity (>95%). In this study, hollow Ni─NC (H‐Ni‐NC) was synthesized using nanoscale silica sphere templates and atomic Zn as a sacrificial pore‐former within the carbon shell. The optimized H‐Ni‐NC achieves a current density of −1.0 A cm −2 with over 95% CO Faradaic efficiency in a flow cell. The high performance was attributed to the hollow sphere architecture enriched with gas‐permeable through‐pores. Notably, the Zn dosage selectively modulates the shell through‐porosity, without altering hollow sphere macrostructure or the active‐site structure, thereby enabling a systematic investigation of porosity effects. Finite‐element simulations provide a qualitative framework suggesting a trade‐off between reactant transport and active surface area with increasing porosity in hollow spherical catalysts. This work underscores that engineering of the nanoscale mass‐transport environment surrounding active sites plays a critical role in designing high‐efficiency electrocatalysts.

Nrf2 dynamically regulates RANKL-induced osteoclastogenesis and cathepsin K function

Decoupling of allele frequency and predicted pathogenicity in the tandem repeat filaggrin (FLG) gene

Abstract Tandemly repetitive genes present a paradox in that their duplicated architecture may buffer against mutation yet often exhibits strong position-dependent functional constraints. The filaggrin gene ( FLG ), with its massive repetitive core, provides a key model to examine how repeat architecture and demographic forces shape variation in such recalcitrant genomic regions. We integrated population-scale data from gnomAD ( n  > 140,000) with deep learning predictions from AlphaMissense to map FLG ’s variant landscape. Constraint metrics indicated relaxed selection (missense o/e = 1.63), yet a clear spatial discordance emerged: predicted pathogenic variants were enriched in terminal repeats, whereas observed allele counts in human populations were concentrated in a few recurrent truncating variants in central repeats. These prevalent alleles exhibited strong alignment with population ancestry, while common variants (AF > 0.01) lacked definitive pathogenic annotations, highlighting the primacy of demographic history over uniform selection. Amino acid composition across repeats revealed significant divergence, with biases in Ser, Gly, and His correlating with predicted pathogenicity, providing a mechanistic basis for repeat-specific evolutionary constraints. Together, these findings demonstrate that variant interpretation in large tandem repeats requires explicit integration of repeat structure and population history. This framework has implications for ancestry-aware assessment of FLG variation and for the broader analysis of repetitive genes in human disease genetics.

Deep functional interpretation of influenza-induced ciliary gene dysregulation through stepwise Large Language Model profiling 2302296

Abstract Introduction The interpretation of large-scale transcriptional data remains a significant challenge in functional genomics, particularly in complex biological contexts such as host-pathogen interactions. Methods We present a systematic approach combining air-liquid interface (ALI) cultures with stepwise Large Language Model (LLM) analysis to achieve deep functional interpretation of ciliary gene regulation during influenza infection. From 2,828 differentially expressed genes, initial high-throughput LLM screening identified 29 genes with high confidence scores specifically associated with ciliated cell biology. We conducted detailed functional profiling of these candidates through human-in-the-loop validation. Results Analysis revealed a coordinated program of ciliary gene dysregulation. Key genes, including DNAH5, DYNC2H1, and DNAAF4-CCPG1, showed consistent downregulation by 24-48 hours post-infection. This pattern was validated across independent datasets from Influenza, Rhinovirus and SARS-CoV-2 infections, suggesting a conserved mechanism of mucociliary clearance impairment across respiratory viral infections. Conclusion By focusing our analysis on ciliated cell-associated genes, we uncovered specific mechanisms of viral pathogenesis while establishing a generalizable framework for context-aware interpretation of complex biological datasets. Funding Source National Institute of Allergy and Infectious Diseases (NIAID) Topic Categories Computational and Systems Immunology (COMP)

Altered lipid metabolite profiles in neurocognitive impairment in long COVID 2309930

Abstract Introduction Long COVID, defined as symptoms persisting for three months or longer following acute SARS-CoV-2 infection, represents a substantial and growing public health burden with limited therapeutic options. Progress in diagnosis and treatment is impeded by clinical heterogeneity, a lack of actionable biomarkers, and the absence of FDA-approved therapeutics. Here, we aimed to characterize alterations in lipid metabolite profiles and circulating cytokine profiles in long COVID. Methods We analyzed infection-naïve and vaccine-naïve individuals with long COVID sampled during the first wave of the COVID-19 pandemic enrolled in the Cedars-Sinai CORALE-EMBARC study. We focused on individuals reporting neurocognitive symptoms, reasoning that symptom-specific cohorts may enable more precise identification of underlying molecular drivers. Long COVID participants were defined as reporting at least one neurocognitive symptom following SARS-CoV-2 infection and were compared to age- and sex-matched never-infected or COVID-recovered participants (n = 135 total). Immune and metabolic profiles were assessed through multiplex serum cytokine analysis and untargeted LC-MS/MS. Results Untargeted plasma lipidomics revealed distinct lipid signatures that differentiated COVID-recovered and neurocognitive long COVID groups following multivariate logistic regression analysis adjusted for age and sex. Lipid metabolite changes included reductions of anti-inflammatory mediators. Interestingly, we did not observe widespread elevations in circulating proinflammatory cytokines in individuals with neurocognitive long COVID. Conclusion These findings suggest that circulating proinflammatory cytokine levels may not reliably distinguish neurocognitive long COVID from COVID-recovered individuals. Instead, we found neurocognitive long COVID to be characterized by distinct lipidomic alterations, implicating lipid mediators as potential contributors to disease pathophysiology and highlighting their promise as therapeutic targets. Funding Source The Clouse Family, The Shiley Foundation, The Shirley and Harry Beer Charitable Foundation, Nancy Vaughan, Nabil and Gayda Hanna, Brad and Rachel Greenwald, Bridget Cresto, James and Katya Hazel, the Prebys Foundation, NIH R01CA256133, UCSD R01CA281285, U Topic Categories Immune Mechanisms of Human Disease (HUM)

A paracrine mTEC/cTEC FGF21—mTOR signaling axis regulates thymic architecture and T cell development across the lifespan 2260524

Abstract Introduction Cortical thymic epithelial cells (cTECs) establish a lymphopoietic thymocyte niche that regulates thymus size and T cell output throughout life. Our recent studies suggest that medullary TEC (mTEC)-derived fibroblast growth factor 21 (FGF21) acts in a paracrine manner to drive temporally distinct patterns of mTORC1 and mTORC2 signaling in cTECs. Thymic overexpression of FGF21 promoted thymus growth, enhanced T cell responsiveness to infection, and reduced indicators of age-associated autoimmunity. However, the cellular mechanisms regulating FGF21-dependent regulation of cTEC function across the lifespan have not been defined. Methods To determine whether cTEC-intrinsic FGF21—mTOR signaling regulates thymic architecture and function, we generated a new mouse model in which β5t-iCre drives cTEC-restricted deletion of the obligate FGF21 co-receptor, Klb, as well as expression of the Confetti multicolor reporter allele (β5t-iCre KlbF/F Confetti). We used flow cytometry and confocal microscopy to assess the kinetics of Klb expression, mTORC1/2 activity, thymic structure, cellular composition, T cell development, and cTEC morphology from birth to middle age in β5t-iCre KlbF/F Confetti mice and littermate controls. Results Together, our results suggest that cTECs directly respond to FGF21 signaling via the Klb receptor, and that mTORC1 and mTORC2 mediate cTEC-intrinsic FGF21 signaling to promote thymus size and function. Conclusion The conclusion is combined with the results. Funding Source NIH R01 AG086271 Topic Categories Hematopoiesis and Immune System Development (HEM)

In-Utero Imprinting of Gene Regulatory Networks Underpinning Innate-Like T Cell Development 2260347

Abstract Introduction The mammalian immune system develops through a layered process in which successive waves of embryonic hematopoiesis give rise to distinct progenitors that seed and sustain the neonatal and adult immune compartments. The tissue-based early immune system prioritizes barrier protection by constraining inflammation, whereas the adult immune system is optimized for durable pathogen control and memory. Methods To define the heterogeneity of embryonic precursors that differentiate into immune subsets emerging early in life, we generated a high-resolution single-cell transcriptomic atlas of mouse embryonic hematopoiesis spanning E8.5-E15.5 at 12-hour intervals, encompassing yolk sac, para-aortic-splanchnopleura/aorta-gonad-mesonephros (PsP/AGM), and fetal liver. Results The atlas resolved canonical myeloid (including tissue-resident macrophages), lymphoid (including ILC progenitors), and stromal lineages. Moreover, it revealed previously uncharacterized progenitors biased toward innate-like and tissue-resident lymphoid fates. Notably, we identify precursors bearing a Sox13, Atv5, Tcf7, Notch1, Myb and Lef1 gene regulatory module that imposes effector identity to IL-17 secreting γδ T (Tγδ17) cells. These cells also express the CBFβ2-RUNX complex consistent with a pioneer/lineage-competence role. Using mice carrying a mutation in the CBFβ2 isoform, previously shown to be essential for γδ T cell development, we demonstrate that CBFβ2 haploinsufficiency rewires transcriptional regulatory circuits in adult bone marrow progenitors, rendering them permissive for an early life-restricted Tγδ17 cells. Conclusion Together, these data provide a reference framework for fetal hematopoiesis and reveal how embryonic gene-regulatory programs encode the foundations of layered immunity. Funding Source n/a Topic Categories Hematopoiesis and Immune System Development (HEM)

CAR-Dependent Bile Acid Adaptation Programs CD8 T Cell Function in Liver Cancer 2310297

Abstract Introduction Bile acids are amphipathic molecules synthesized in pericentral hepatocytes derived from cholesterol that facilitate lipid digestion and absorption. In addition to their role in fat emulsification, bile acids act as signaling molecules that regulate numerous metabolic and immune processes through their interactions with nuclear receptors, including the farnesoid X receptor, pregnane X receptor, vitamin D receptor, and constitutive androstane receptor (CAR). These receptors orchestrate bile acid homeostasis, modulate inflammatory pathways, and influence immune cell function. While the role of each of these bile acid receptors has been extensively studied in hepatocytes, their role within immune cells, particularly in CD8 T cells, is understudied. He we demonstrate CAR deletion modulates CD8 T cell persistence and effector function in mouse models of hepatocellular carcinoma (HCC). Methods We delivered AAV8-TBG-Cre-U6-gRNA (Baat or scramble) to AST-Cas9 mice (Albumin-floxStop-SV40 large T antigen), to induce tumor while simultaneously knocking out BAAT enzyme in hepatocytes to perturb bile acid metabolism. Wild type or CAR deficient SV40-specific T cells we adoptively transferred 2 wks dpi and assessed at 5 wks dpi via flow cytometry and scRNAseq. CAR was overexpressed using retrovirus in in-vitro activated CD8s cultured in the presence of various bile acids and cytokine and assessed for its ability to modulate efflux of Rh123 Results In-vitro over-expression assays highlight a role for CAR and cytokine in the induction of bile acid efflux transporters. Adoptive transfer of CAR deficient tumor specific T cells highlights the role of CAR in T cell intrinsic adaptation to bile acid signaling in inflamed hepatic environments. Conclusion Our findings highlight a broader role for CAR in regulating immune cell adaptation to tissue-specific metabolic stress. Funding Source Principal investigator has institutional start-up funds Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)

Tissue resident memory cells formed after neonatal viral infection contribute to asthma 2255698

Abstract Introduction Viral lower respiratory tract infections are remarkably common amongst children less than 5 years old. Human metapneumovirus (HMPV) is one leading cause of these infections in children under 5 years old. Additionally, infants diagnosed with HMPV bronchiolitis are at a four-fold increased risk of developing asthma. The mechanisms by which early-life HMPV infection influences long-term immune responses remain poorly understood. Methods To model this clinical phenomenon, neonatal or adult mice were infected with HMPV, then re-challenged 6 weeks later. We assessed mucus, airway reactivity, eosinophil recruitment, and T cell subset phenotypes. FTY720 and anti-CD4 were used to modulate TRM populations. Treatment with fedratinib, a Jak2-selective, was performed on the first 3 days of rechallenge via oral gavage. Results We demonstrated that neonatal mice re-challenged with HMPV as adults mount a robust Th2 response consistent with asthma pathology (e.g. eosinophil recruitment, mucus production, and airway hyperreactivity). Mice initially infected with HMPV as adults followed by HMPV re-challenge showed no signs of Th2 inflammation. The tissue resident memory compartment (TRMs) also showed evidence of Th2-skewing following neonatal, but not adult, HMPV infection. Mice treated with FTY720, an inhibitor of lymphocyte trafficking, had a robust Th2 response in the neonatal/adult rechallenge model. Local and systemic depletion of CD4+ T cells mitigated this response. Further, this subset of enriched Th2 TRMs following neonatal HMPV had a unique transcriptional profile, including differential expression Jak2. Mice treated with fedratinib showed reduced eosinophil recruitment, Th2 cytokine production, and mucus hypersecretion compared to vehicle controls. Conclusion Collectively, these studies identify a targetable Th2 TRM population following early life infection that can contribute to asthma-like inflammation following re-exposure to a viral pathogen. Funding Source The AAAAI Foundation Faculty Development Award and NIAID Topic Categories Immediate Hypersensitivity, Asthma, and Allergic Responses (HYP)

Structural and biological bases of cGAS bending bubble DNA to form a hyperactive dimer 2310028

Abstract Introduction The abnormal presence of DNA in the cytosol signals diverse intracellular crises. Cyclic GMP-AMP synthase (cGAS) is a predominant pattern-recognition receptor for double-stranded DNA (dsDNA), forming 2:2 cGAS-DNA dimers that further oligomerize into phase-separated condensate to initiate interferon responses. However, immunostimulatory DNA is rarely a perfectly contiguous duplex; instead, it frequently harbors additional conformations and local structures. How cGAS senses and responds to such nonlinear or non-contiguous dsDNAs remains poorly appreciated. Methods To address this, we created dsDNA containing unpaired regions, termed bubble DNA (Bu-DNA), and examined macrophage responses to Bu-DNA across multiple DNA topologies. To elucidate the underlying mechanism, we determined cryo-EM structures and performed biochemical, biophysical and single-molecule FRET (sm-FRET) analyses. Results Here, we demonstrate that Bu-DNA engages cGAS through a distinct binding configuration, eliciting enhanced signaling and cytokine production. Hyperactivation is observed by Bu-DNA embedded in linear DNA, circular DNA, plasmids and mitochondrial DNA. Bu-DNA binds cGAS with significantly higher affinity than fully complementary dsDNA, yet suppresses higher-order condensation. We further reveal that cGAS forms a 2cGAS:1DNA complex by bending Bu-DNA into a V-shape using the unpaired region as a hinge, thereby limiting its oligomeric state. Conclusion Taken together, these findings uncover a novel mode of cGAS activation and highlight the versatility of host defense strategies, in which cGAS recognizes structural features as a “pattern within a pattern” to fine-tune inflammatory responses. Funding Source NIH R01AI029564, R35CA232109, R01AI158314 (J.P-Y.T) and R35GM145363 (J.S) Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)

Charge–Transfer Reversal at Cl‐Regulated Cu ₂ O/in ₂ S ₃ Interfaces Enables C─C Coupling for Selective CO ₂ Photoreduction to C ₂ H ₄

ABSTRACT Efficient photocatalytic CO 2 reduction to C 2 H 4 is often constrained by sluggish C─C coupling kinetics and inefficient charge utilization. In this study, a Cl‐regulated reversed charge‐transfer pathway in Cu 2 O/In 2 S 3 heterojunction switches the photocatalytic CO 2 reduction product from CO to C 2 H 4 . This is attributed to Cl incorporation into the Cu 2 O lattice, which induces p‐type to n‐type conversion and reversed interfacial electric field (IEF), driving the transformation of Cu 2 O/In 2 S 3 (CIS) from a type‐II heterostructure to a Z‐scheme heterojunction in Cl‐Cu 2 O/In 2 S 3 (CCIS). The tailored charge transfer pathway enables Cl‐Cu 2 O to act as the CO 2 reduction center, and Cl‐modified electronic structure of Cu sites stabilizes *CO intermediates and lowers the C─C coupling barrier. Meanwhile, In 2 S 3 promotes H 2 O oxidation to provide sufficient protons and further accelerates the proton‐coupled electron transfer (PCET) process. Accordingly, CCIS exhibits an impressive C 2 H 4 evolution rate of 115.3 µmol g −1 h −1 and 91.4% selectivity in pure water, with an apparent quantum efficiency (AQE) of 5.4% at 420 nm. These findings highlight the significance of designing photocatalysts with favorable charge transport to tailor product selectivity in CO 2 photoreduction.

Phosphatidylethanolamine binds to human perilipins via a hydrophobic cleft in their 4-helix bundle domain for lipid droplet targeting

Passenger density prediction and gate allocation via GA-optimized ELM

Viable but nonculturable Francisella tularensis is attenuated in a murine model 2300563

Abstract Introduction Francisella tularensis is a gram-negative intracellular bacterium that causes tularemia. F. tularensis LVS (a live vaccine attenuated surrogate strain) rapidly transitions to a viable but nonculturable state (VBNC) on media while maintaining viability and the ability to invade host cells. The role of VBNC in F. tularensis remains to be determined; however, in other pathogenic bacteria, it allows survival in hostile environments which would be experienced in nature or infections. Therefore, our study aimed to understand the effect of VBNC on pathogenesis in F. tularensis in a mammalian host model by determining whether cells remain VBNC or resuscitate to normal cellular activity. Methods To assess virulence and bacterial burden, BALB/c mice were intranasally challenged with varying doses of viable or VBNC LVS. At 21 days post challenge, tissues were homogenized and plated to determine CFU. We optimized flow cytometry protocols to quantify VBNC LVS in tissue samples to determine absolute cell counts by viability staining and immunolabeling. Results These experiments showed VBNC LVS remained attenuated in mice, displaying no morbidity or mortality for up to 21 days post-challenge. In contrast, mice challenged with viable LVS succumbed to challenge. Although VBNC LVS remained attenuated, bacteria were still detected in the lungs and spleen at the end of study based upon flow cytometry analysis. Additionally, mice challenged with VBNC LVS displayed no innate immune response from flow cytometry analysis of a myeloid cell panel. Surviving mice of the VBNC cohort were rechallenged with viable LVS or fully virulent Schu S4 to assess protection status. This revealed that VBNC exposure provided full protection against parental LVS re-challenge but afforded no protection against the Schu S4 strain. Conclusion Taken together, this work demonstrates VBNC LVS did not resuscitate upon entering a murine host by this challenge method. Furthermore, the VBNC state can provide protection against its parent strain. Funding Source DTRA-JSTO Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Physical interactions of lung CD4 T cells and infected antigen-presenting cells mediate protection in tuberculosis 2309801

Abstract Introduction New vaccines against tuberculosis are impeded by gaps in knowledge about the CD4 T cell response to Mycobacterium tuberculosis (Mtb). Although millions of CD4 T cells are recruited to the lungs, few are activated by antigen recognition to carry out protective effector functions. And while phagocytic cells harboring intracellular Mtb benefit from direct recognition by CD4 T cells, the mechanisms of protection mediated by this physical interaction are unknown. New technical approaches are needed to decipher which CD4 T cell effector functions depend on cellular contact and to define which Mtb antigen specificities enable direct recognition of infected antigen presentation cells (APCs) via TCR-peptide:MHC II binding. Methods Using gentle tissue digestion and flow sorting, we isolated CD4 T cell/APC multiplets from the lungs of mice infected with fluorescent Mtb. We used microscopy, chip cytometry, and sequencing analyses to enable comprehensive phenotyping and visualization of the immunological unit that drives protective immunity against Mtb. Further, we used mixed bone marrow chimeras to determine whether protection mediated by the crucial cytokine IFN-γ depends on direct recognition. Results CD4 T cell/APC multiplets in the lungs were induced by Mtb infection, peaked at week 4 post-infection, and partially depended on MHCII expression by monocyte derived cells. Sorted multiplets visualized with microscopy were spatially consistent with immunological conjugates. Within the CD4 T cell repertoire of a mouse, there was relative enrichment of key Mtb-reactive TCR clonotypes among CD4 T cells interacting with Mtb+ APCs. Among cellular conjugates from the lungs of Ifng-/- mixed bone marrow chimeric mice, those unable to produce IFN-γ at the immune synapse had higher percentages of intracellular Mtb and failed to upregulate IFN-responsive pathways. Conclusion Direct CD4 T cell recognition of Mtb-infected APCs forms protective synapses that enrich Mtb-specific TCRs and focus IFN-γ—mediated immunity. Funding Source R01AI193512 Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Pharmacological activation of LANCL2 is a novel immunometabolic mechanism for the treatment of psoriasis 2260624

Abstract Introduction Psoriasis (PsO) is a chronic, inflammatory skin disease that afflicts 125 million people. Despite advancements in treatments, an unmet clinical need remains for safer and more effective therapeutics. LANCL2 is a novel immunoregulatory target for the treatment of a wide range of inflammatory and autoimmune diseases, including PsO. Methods We utilized the imiquimod (IMQ) mouse model to conduct comparative therapeutic studies of topical omilancor against current PsO standard of care (SOC) therapies such as anti-IL17, betamethasone and methotrexate. We also evaluated the therapeutic efficacy of next-generation oral LANCL2 drugs. Mice were challenged with IMQ in shaved dorsal skin for 7 d. Skin was evaluated for inflammatory lesions and immune cell subset infiltration. Proinflammatory cytokine production of PBMCs isolated from PsO patients was assessed in vitro upon pharmacological activation of LANCL2. Results LANCL2 therapeutics outperformed SOC and demonstrated the largest decrease in disease severity and typical signs of psoriatic lesions (epidermal hyperplasia and hyperkeratosis). Topical omilancor demonstrated similar efficacy reducing skin inflammation to the anti-IL-17 and betamethasone groups with the greatest decrease in skin inflammatory infiltrates and expression of proinflammatory mediators (Ccl20, S100A9, Il6). Next-generation LANCL2 drugs ameliorated disease severity and reduced the infiltration of proinflammatory subsets (neutrophils, IL-17+ cells). In translational studies using human PBMCs, activation of LANCL2 activation resulted in decreased production of proinflammatory cytokines (IL-8, IL1b, IL-6). Conclusion NIMML has characterized LANCL2 as a unique immunometabolic target for the treatment of PsO and demonstrated that LANCL2 therapeutics outperform SOC therapies to ameliorate disease, skin inflammatory lesions and to reduce systemic inflammation while managing comorbidities through oral, once-daily pharmacological LANCL2 activation. Funding Source N/A Topic Categories Therapeutic Approaches to Autoimmunity (THER)

Plasmacytoid dendritic cell discrete subpopulations with contrasting functions are elicited by CD4+ T cells infected or not by HIV-1 or HIV-2 2260395

Abstract Introduction Plasmacytoid dendritic cells (pDC) are major interferon (IFN)-α producing-cells in response to viruses. After maturation, they stimulate T cells. We found that they cross-present antigens from HIV-1-infected CD4+ T cells to specific cytotoxic T cells. During primary HIV infection, IFNs are essential to decrease viral loads, but during chronic infection, they induce immune suppression and metabolic syndrome. Free influenza or Sars-Cov2 viruses were shown by cytometry to induce pDC diversification. Because HIV is rarely free, we stimulated pDC by HIV-1 or 2-infected H9 CD4+ T cells to assess diversification. Methods Human pDC were purified from buffy coats by immunomagnetic depletion and CD304+ BD AriaIII sorting, stimulated for 16h by H9 cells, tested by flow cytometry (BD LSR2), multiparametric spectral cytometry (Cytek Aurora, Omics) and single-cell RNA sequencing (scRNAseq, Chromium Next Gem-X Flex 10x Genomics, Illumina NextSeq2000, Human genome GRCh38-2024-1, R v4.05, Seurat, DGE, UMAP, GOE, pseudo-trajectory). Results HIV-infected CD4+ T cells induced diversification of pDC into IFN-α and IFN-γ-producing, or mature pDC with T-cell stimulatory potential (CD83), or cytotoxic cells (CD107a, target H9HIV cell apoptosis). Spectral cytometry showed diversification into 10 subpopulations with different functions. scRNAseq showed that H9 cells induced pDC with TLR7/9 signaling pathway, HIV-1 or-2-infected H9 cells induced additional subpopulations with IFN-α and -γ (more with HIV-2), IFN-Stimulated Genes (more with HIV-1), cytotoxicity, T cell activation and regulation genes. Conclusion H9 cells induced pDC primed for viral activation, HIV-infected H9 cells induced more populations with surprisingly contrasted functions and differences between HIV-1 and 2 infections which may explain HIV-2 lower pathogenicity. Understanding pDC diversification will enable development of targeted immunotherapeutic strategies to control HIV through adequate modulation of IFN production and cytotoxic T cell responses. Funding Source French Government’s Investissement d’Avenir program, Laboratoires d’Excellence “Integrative Biology of Emerging Infectious Diseases” (ANR-10-LABX-62-IBEID) ANRS Topic Categories Viral Immunology (VIR)