Browse Articles

Antigen-presenting cell—T cell interactions shaping immune responses to intestinal antigens 2308241

Abstract Introduction The intestinal immune system must concomitantly tolerate food and commensals and protect against pathogens. Antigen-presenting cells (APCs) orchestrate these immune responses by presenting luminal antigens and inducing the differentiation of CD4+ T cells into regulatory (pTreg) or inflammatory (Th) subsets. Methods We combined multiple LIPSTIC tools with interaction-based transcriptomics, mouse genetic approaches, and genetically engineered bacteria to identify APCs that present dietary and microbiota antigens under tolerogenic and inflammatory conditions. Results We show that antigen presentation by distinct subsets of APCs drives specific Th or pTreg differentiation. Microbial or dietary antigen presentation by migratory cDC1s and Rorgt+ APCs was associated with pTreg differentiation. Antigen presentation by intestinal cDC2 subsets results in diverse outcomes, ranging from Th2 or Th17 differentiation to impaired pTreg induction. Conclusion Our data uncover the cellular mechanisms by which T cell differentiation to microbial or dietary antigens is induced based on APCs dynamics. Funding Source K99/R00 Pathway to Independence Award NIAID, NIH Topic Categories Mucosal and Regional Immunology (MUC)

Understanding the role of innate immunity in the lung pathogenesis of Mycobacterium abscessus infection 2303168

Abstract Introduction Infections by Mycobacterium abscessus (MAB), a saprophytic bacterium, are rising globally. While most people exposed do not get infected, immunocompromised individuals, or those with lung conditions like cystic fibrosis, can develop pulmonary MAB disease (MAB-PD). Our research shows GM-CSF is crucial for early pulmonary MAB clearance. GM-CSF is vital for alveolar macrophage (AM) and granulocyte maturation. We hypothesize that both AM and neutrophils are needed to control bacterial growth in early infection stages. Methods We measured the bacterial load in the lungs of immunocompetent C57BL/6 mice depleted of neutrophils and/or AM. To demonstrate that AM are essential for MAB clearance, we depleted AM using clodronate liposomes and neutrophils, combined with two monoclonal antibodies (anti-Ly6G and anti-Ly6C). After depletion, mice were exposed to a MAB aerosol. Mice were euthanized, and lungs, blood, bone marrow, and bronchoalveolar lavage were collected. Bacterial burden in the lungs was assessed, and the presence or absence of AMs and neutrophils during infection was determined by flow cytometry. Results We monitored the frequency of AM and neutrophils in the lungs using flow cytometry at 3, 10, and 15 days post-infection (DPI). While control mice (untreated) and mice depleted of AM or neutrophils showed a significant reduction in bacterial burden in the lungs at 10 and 15 days post-infection, mice depleted of both AM and neutrophils were unable to control the infection by day 10. However, their bacterial load was reduced by day 15. Conclusion Our preliminary results demonstrate the essential, cooperative roles of both AM and neutrophils in the early containment and control of MAB infection within the pulmonary environment. We are currently employing multi-parameter flow cytometry to analyze potential compensatory cellular mechanisms in secondary lymphoid organs, specifically the bone marrow and blood, following the depletion of these key subsets. Funding Source RO1 AI155922 Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Electrochemically Programmed Electromagnetic Camouflage Through Reconstructing Atomic Coordination

ABSTRACT Electrochemical ion injection enables the active control of electronic structures and thereby electromagnetic camouflage. However, the effect of atomically coordinative evolution, such as displacement and clustering, on electromagnetic response remains unclear. Herein, we demonstrate abnormal enhancement of dielectric polarization due to the electrochemical reconstruction of ripples, single atoms, and clusters. The initial crystalline distortion promotes the dielectric screening to produce the polarization hotspot. Subsequently, the reduced Mo single atoms and their clusters form local dipoles. These effects allow modulation of reflection loss value within −4.5 to −23.5 dB. A pixelated framework with charged/discharged “on/off” units realizes the programmable electromagnetic camouflage.

Integrating condensates into protein lifespan – From birth to death

Multi-detection biosensor for assessing senescent microglia and neuroinflammation using interdigitated microelectrodes

From Classroom to Clinic: Using Analogies to Clarify Immunology Concepts and Connect with Patients 2240046

Abstract Introduction Utilizing existing knowledge can build associations that support learning, understanding and communication of complex concepts. Analogies allow the unknown to become familiar, serving as cognitive bridges to deeper understanding. In medical education, analogies have been utilized to increase depth of understanding, with students often creating their own analogies to teach their peers. We aimed to assess the impact of using analogies as a teaching tool for complex immunological concepts in the classroom and the extension of their use in clinical practice. Methods Analogies were integrated into didactic class sessions to teach complex immunology topics. Students were encouraged to create their own analogies, reinforcing their understanding and enabling them to communicate scientific concepts more effectively. Students were surveyed at the end of course blocks to assess the effectiveness of analogies in understanding complex immunological concepts. Second-year medical students received a second survey at the end of the year to assess the effectiveness of analogies for communication with patients. Results Students self-reported increased confidence in their understanding and retention of immunological material. They noted that analogies enhanced their learning experience and provided a strong conceptual foundation for building more detailed and nuanced knowledge. The second-year medical students reported widespread use and effectiveness of analogies in educating patients about complex medical terms, diagnoses, procedures and treatment plans. Conclusion Incorporating analogies into immunology education supports both cognitive and communicative skill development. Further, medical students reported widespread use and effectiveness of analogies in the clinical space. This approach not only improves comprehension and retention but also equips students with tools for effective communication with patients and the public about medical conditions and scientific advancements. Funding Source n/a Topic Categories Immunology Education and Communication (EDU)

Type I interferons prevent cell death and liver immunopathology in Mouse Hepatitis Virus infected mice 2333173

Abstract Introduction Type I interferons (IFNs) hinder the viral replication process and regulate the immune system to mount an antiviral response. However, there is little research on how type I IFNs can prevent virally induced immunopathology. The mouse hepatitis virus (MHV) is a highly contagious murine pathogen that exhibits broad cellular tropism and leads to a plethora of symptoms, including fulminant hepatitis. Despite being a mouse-specific pathogen, using MHV as a model can help us understand the development of immunopathology in the absence of type I IFN signalling. Methods Type I IFN receptor knockout (IFNAR-/-) and wild-type (WT) C57BL/6 mice were infected with MHV-A58 through oral gavage and intraperitoneal injections. Serum and liver homogenates were used for measuring viral titres and cytokine array analyses. Disulfiram was administered intraperitoneally to inhibit pyroptosis. Liver lobes were sent for histology to study the immunopathology of the disease. Results IFNAR-/- mice were highly susceptible to MHV infection compared to WT mice, experiencing lethal immunopathology in the liver, a cytokine storm, and significantly higher viral titres. Liver histology of infected IFNAR-/- mice exhibited high levels of hemorrhaging and necrosis. This data suggested that type I IFN signalling was not only critical for stemming the spread of the infection but also for preventing the development of lethal immunopathology. To elucidate the mechanism, we studied their role in cell death pathways in hepatocytes. Inhibition of pyroptosis led to decreased liver immunopathology and inflammation with no effect on the viral titres. This suggested that type I IFNs can prevent pyroptosis to limit liver immunopathology during MHV infections. Conclusion Research on how type I IFNs can regulate and prevent the development of lethal immunopathology is critical for advancing therapeutic strategies against hyperinflammatory disease during viral infection. Funding Source Canadian Institutes of Health Research Topic Categories Viral Immunology (VIR)

Unravelling mitochondrial dynamics in T cells using high-speed image-enabled flow cytometry 2302022

Abstract Introduction T cells have critical roles in immune response to infections, tumors, and other pathologies, and their efficacy is rooted in their functional and metabolic status. Mitochondria are important intracellular organelles intertwined with T cell metabolism and function. Upon T cell activation, mitochondria undergo dynamic remodeling marked by a series of structural changes associated with efficient electron transport and metabolic transitions. Failure to induce these metabolic changes can prevent T cell proliferation, activation and effector function. Although mitochondrial structure and metabolic programs are of wide interest to researchers, tools for rapidly assessing T cell mitochondrial morphology together with other phenotypic features remain limited. Methods Currently, researchers utilize various microscopy techniques to visualize mitochondria, which is technically demanding and can be biased due to limited number of images available for analysis. In this study, we addressed this technical gap by leveraging high-speed imaging flow cytometry to enable interrogation of mitochondrial dynamics in T cells. Results Using an in vitro system of T-cell activation that recapitulated increases in the number and volume of mitochondria, we identified unique mitochondrial phenotypes using a high-speed imaging flow cytometer. A set of intuitive spatial image parameters were examined to select ideal parameters based on unsupervised clustering. Using these imaging parameters, we quantified and sorted T cells with distinct mitochondrial morphology at high speed. Subsequent transcriptomic characterization revealed metabolic heterogeneity associated with distinct mitochondrial phenotypes, validating the new imaging flow cytometry and cell sorting method. Conclusion This work develops a high-throughput method to characterize phenotypic variation in mitochondrial morphology, and provides a workflow integrating cell activation, sorting, and transcriptomics to elucidate mechanisms underlying mitochondrial dynamics. Funding Source n/a Topic Categories Technological Innovations in Immunology (TECH)

Novel hybrid exam introduces new medical students to collaborative learning and board style questions 2306372

Abstract Introduction NBME (National Board of Medical Examiners)—style questions underpin medical school exams, yet opportunities for collaborative engagement with content is limited by disclosure policies. Two-stage ungraded hybrid exams–completed individually and then in small groups–may improve reasoning, clarify misconceptions, and reduce anxiety around vignette-based items, especially in immunology. This study evaluated how a hybrid exam influenced first-year medical students’ (MS1s) learning experiences and readiness for a graded summative exam. Methods This longitudinal study surveyed MS1s at baseline, after the hybrid exam, and after the summative exam using Likert-scale items assessing confidence, strategies, anxiety, belonging, and collaboration. Identical items enabled longitudinal comparisons, and Wilcoxon signed-rank tests analyzed change scores. Results At baseline, confidence with NBME-style questions (M = 3.39, n = 80) and multistep vignettes (M = 3.13) was modest, while anxiety (M = 5.24) and intimidation (M = 5.15) were elevated. After the hybrid exam, clarity improved (M = 5.03, n = 65), understanding increased (M = 5.26), peer support strengthened (M = 5.58), and anxiety decreased (M = 4.92). Following the summative exam, students applied hybrid-exam strategies (M = 5.29, n = 56), felt better prepared (M = 5.54), and showed improved understanding (M = 5.07) and confidence (M = 5.23). Longitudinal analyses revealed significant gains in study strategies (median Δ = +2.5), materials knowledge (Δ = +3), time management (Δ = +1), belonging (Δ = +1), and composite preparedness (median Δ = +2.17), all p < .001. Conclusion A hybrid NBME-style exam may aid MS1s’ transition into board-style reasoning by improving clarity, understanding, and exam approach. Early exposure to NBME material–particularly in immunology–may strengthen test-taking strategies and reduce exam stress. Future work should assess whether these gains translate to objective outcomes and if the model can be tested at other medical schools. Funding Source This project was supported by the ITLE Healthcare Education Grant Award (HEGA) awarded to Dr. Cusick, and by a CNUCOM intramural grant awarded to Dr. Gerriets. Topic Categories Immunology Education and Communication (EDU)

Impact of Buprenorphine Extended-Release (Ethiqa XR) on mice exposed to aerosolized Burkholderia pseudomallei and Yersinia pestis 2253137

Abstract Introduction Buprenorphine is a potent partial opioid used to manage pain and opioid dependence. The buprenorphine extended-release formulation, Ethiqa XR (Ethiqa), has been FDA-indexed for mice and other laboratory species to relieve pain, however, several reports indicate that Ethiqa can alter the inflammatory response in various in vivo models. Therefore, it is necessary to understand the effect of Ethiqa on disease pathogenesis prior to its use during animal studies. Methods Here, we evaluated the effects of Ethiqa treatment prior to and 48h after bacterial challenge of C57BL/6 and BALB/c mice with Burkholderia pseudomallei and Yersinia pestis. Results Both mouse strains challenged with aerosolized Burkholderia pseudomallei K96243 demonstrated increased bacterial dissemination to the spleen when treated with Ethiqa. Consistently, splenocytes had elevated pro-inflammatory cytokines such as IFN-gamma, IL-6, IL-22, TNF-alpha, among others, as well as elevated levels of iNOS. The C57BL/6 mice also displayed elevated IFN-gamma and IP-10/CXCL10 in lung and brain homogenates. In contrast, no profound differences were observed in either mouse strain treated with Ethiqa and challenged with Yersinia pestis CO92. In the absence of challenge, treatment with Ethiqa did not change the cytokine responses in the lung, brain, or spleen of BALB/c mice but increased the concentration of IL-6 and TNF-alpha in the lungs of C57BL/6 mice. Conclusion Taken together, these results suggest the effects of Ethiqa may be model-specific and introduce confounding effects that would impact dependent variables. Funding Source DTRA-JSTO Topic Categories Cellular Adhesion, Migration, and Inflammation (CAM)

The Effects of Granulocyte Macrophage Stimulating Factor on Cancer Cell Viability in vitro and in vivo 2307997

Abstract Introduction Previous research has shown that mast cells (MC) can induce cancer cell apoptosis through the release of mediators they produce following FcεRI and non-FcεRI mechanisms. However, it is not clear which mediators induce this response. Mast cells produce copious amounts of Granulocyte Macrophage Stimulating Factor (GMCSF) which is primarily known for stimulating the immune system by activating and recruiting white blood cells. The purpose of this study was to determine what direct effect GMCSF has on cancer cells in vitro and in vivo. Methods Several human cancer cell lines including: AU565, BT474, and MDA-MB-231 were incubated with varying concentrations of human GMCSF and the morphological changes and viability were assessed in vitro. For in vivo studies, tumors were established in Nu/Nu immunocompromised mice after injection with the same cancer cells. Mouse tumors were injected with or without varying concentrations of GMCSF and tumor size and lifespan measured. Results Statistically significant cancer apoptosis was determined using flow cytometry of the in vitro study. In Vivo studies are underway. Conclusion GMCSF may have a direct killing effect on cancer cells in addition to the well-established immune stimulation actions described previously. These results also suggest this mechanism contributes to anti-tumor effects of MC and provide guidance in rationally designing MC for cancer immunotherapy strategies. Funding Source National Institutes of Health, 1R15CA46430-01A1 Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

RPS6 Phosphorylation Shapes Effector/Memory Balance and Recall Function of CD8 T Cells 2305349

Abstract Introduction Durable CD8 T cell memory is critical for long‑term protection and immunotherapy. mTORC1 promotes effector differentiation but, when overactive, limits T cell memory formation. Phosphorylation of ribosomal protein S6 (pRPS6), a classic mTORC1-S6K output, is usually viewed as a passive readout. Whether pRPS6 itself shapes CD8 T cell fate, metabolism, and recall capacity remains unclear. Methods Rps6 5A/5A knock-in mice with non-phosphorylatable RPS6 were crossed with pmel transgenic mice. Effector and memory subsets were defined by CD44/CD62L. Metabolism was evaluated by Seahorse assays (ECAR, OCR). T-bet protein was quantified by intracellular staining. For chronic in vitro stimulation, CD8 T cells were restimulated with irradiated B16 melanoma every 3—4 days, and cytotoxicity was measured by RTCA and cytokine ELISA. For in vivo memory and tumor control, 5-day effector CD8 T cells from Rps6 wt/wt or Rps6 5A/5A pmel mice were rested 30 days in tumor-free hosts, then challenged with B16. Results Rps6 5A/5A CD8 T cells displayed increased glycolytic flux, higher T‑bet, and reduced Tcm frequencies, indicating a glycolysis‑biased, effector‑skewed phenotype. Under repeated restimulation with B16 cells, Rps6 5A/5A pmel CD8 T cells outperformed wild‑type cells in short‑term target killing. In contrast, when 5-day effector CD8 T cells were rested in vivo for 30 days, and then tumor-challenged, Rps6 5A/5A pmel cells controlled tumors less effectively than WT, revealing impaired memory phase protection despite robust early effector activity. Conclusion These data identify pRPS6 as a regulatory checkpoint rather than a passive mTORC1 marker. By limiting T‑bet expression and restraining glycolytic overactivation, pRPS6 helps maintain CD8 T cell memory potential. Loss of pRPS6 enhances effector function yet compromises long-term tumor control, revealing a trade-off between immediate cytotoxicity and durable CD8 T cell memory. Funding Source NIH (1R01CA250514-01) Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)

Monomeric Insulin Analog and Stabilizing Excipient Enabled Ultrafast Insulin Formulation

ABSTRACT The speed of insulin therapy remains fundamentally constrained by the self‐association of insulin into hexamers. Here, a materials‐based strategy is introduced to stabilize HALQ, a monomeric insulin analog, using a non‐interacting inulin‐derived excipient (BN‐Inu). BN‐Inu markedly mitigates aggregation and maintains HALQ stability for 96 h under stress and for at least 30 days at room temperature. In a porcine model of diabetes, monomeric HALQ exhibits significantly accelerated absorption and a shorter duration of action than the ultrarapid insulin aspart Fiasp. This “fast‐on, fast‐off” profile is consistent with faster clearance from the subcutaneous depot, more closely synchronizes with endogenous prandial insulin physiology. Addition of clinically used absorption enhancers further accelerates its pharmacokinetic profile, producing a faster time‐to‐peak and reduced exposure relative to ultrarapid insulin lispro Lyumjev in this animal model. Furthermore, translation to human physiology was evaluated through pharmacokinetic modeling, which predicts that HALQ could reduce time‐to‐peak from 60 to 39 min and shorten duration of action from 143 to 84 min in humans. These simulations suggest the potential utility of achieving a step‐change in the speed of insulin therapy. These findings demonstrate that monomer‐stabilizing excipients enable next‐generation ultrafast insulin formulations with the potential to improve glycemic control in diabetes.

Erythroferrone antagonism of BMPs is governed by a composite heparin-binding motif

Development and evaluation of an Indian Language-Adjusted Gain model for hearing aid fitting in Malayalam and Kannada speakers

Sensory neuronal regulation of intestinal inflammation and immunity 2238700

Abstract Introduction Pain is a hallmark of infection and inflammation, but the role of pain-sensing nociceptors in tissue immunity is poorly defined. We previously showed that gut-innervating TRPV1+ nociceptors shape the intestinal microbiota to promote protection upon acute injury (Zhang et al., Cell 2022), highlighting their immunoregulatory function. At barrier surfaces, type 2 inflammation is an evolutionarily conserved response driving parasite defense, allergy, and repair, initiated by epithelial and immune sensing and further modulated by neuronal signals. How these diverse inputs are coordinated and integrated, however, is poorly understood. Methods In this study, we utilize mouse chemogenetics, scRNA sequencing, spatial transcriptomics, 3D tissue imaging and computational analyses to interrogate the functional interactions between sensory neurons, chemosensory tuft cells and anti-helminth type 2 immune responses. Results We demonstrated that TRPV1+ nociceptors co-opt chemosensory tuft cells to orchestrate protective anti-helminth type 2 immunity. Chemogenetic silencing of TRPV1+ nociceptors resulted in significantly reduced intestinal tuft cells and defective anti-helminth type 2 immunity. Conversely, chemogenetic activation of TRPV1+ nociceptors lead to enhanced intestinal CGRP+ innervation, increased tuft cell accumulation and protective anti-helminth type 2 immunity. Spatial transcriptomic analysis revealed nociceptor activation stimulated rapid epithelial progenitor proliferation and differentiation associated with tuft cell accumulation. Mechanistically, intestinal epithelial cell-intrinsic expression of CGRP receptors were required for anti-helminth type 2 immunity. Conclusion These findings identify a previously unrecognized neuronal—tuft cell circuit as a key upstream regulator of mucosal type 2 immunity (Zhang et al., Nature, accepted), establishing a new paradigm in which peripheral sensory neurons and chemosensory epithelial cells converge to initiate protective immunity at barrier surfaces. Funding Source 2024 NIDDK K99/R00 Transitional to Independence Award, 2024 MIST Scholar Award, Allen Discovery Center program Topic Categories Mucosal and Regional Immunology (MUC)

Investigating the role of Candida albicans gastrointestinal colonization on immune checkpoint therapy 2305444

Abstract Introduction Immune checkpoint therapies (ICTs) have revolutionized cancer treatment, yet most patients remain unresponsive. While the gut bacterial microbiota can influence ICT efficacy, the contribution of the gut fungal mycobiota remains poorly understood. Candida albicans (Ca), a predominant commensal fungus in the human gut, is linked to worse outcomes in several cancers. Additionally, a recent clinical study reported higher levels of Ca colonization in melanoma patients with poor responses to anti—PD-1 therapy. Using preclinical tumor models, we aim to investigate how gastrointestinal colonization with Ca affects ICT immune response. Methods C57BL/6 mice were orally colonized with Ca every other day, starting one week before tumor inoculation until the end of the experiment. When tumors reached ∼80 mm³, mice received ICT (anti—PD-1 +/- anti—CTLA-4) intraperitoneally every four days, for three doses. Mesenteric lymph nodes and tumor-draining lymph nodes were immunophenotyped before ICT initiation or 24 hours after the second dose. Results Ca colonization significantly impaired immune checkpoint therapy (ICT) efficacy in B16-F10 melanoma—bearing mice but not in MC38 colorectal tumor—bearing mice. This inhibitory effect in melanoma was dependent on an intact gut bacterial microbiota, as antibiotic treatment abrogated the phenotype. Immunophenotyping revealed a marked accumulation of RORγt+CD4+ (Th17) cells in mesenteric and tumor-draining lymph nodes of colonized mice both before and after ICT administration. In addition, Ca colonization was associated with an increase in neutrophils in tumor draining lymph nodes prior to ICT, possibly contributing to the development of an immunosuppressive microenvironment. Conclusion These findings suggest that Ca colonization compromises ICT efficacy in a microbiota-dependent manner, potentially through Th17-driven immunosuppressive mechanisms. Ongoing work will define how Ca alters gut bacterial composition and metabolites to modulate anti-tumor immunity. Funding Source N/A Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Investigating a TREM2-TLR2 axis mediating Staphylococcus aureus infection 2329158

Abstract Introduction Staphylococcus aureus can express a large arsenal of virulence factors, readily acquire antibiotic resistance, and survive harsh environmental conditions through biofilm formation. These traits facilitate evasion of host immunity and antibiotic killing, leading to chronic infections. A better understanding of pathogenicity and immune evasion are critical for more effective treatments. In a mouse model of S. aureus biofilm infection, we uncovered a critical role for triggering receptor expressed on myeloid cells-2 (TREM2) in exacerbating infection severity via anti-inflammatory responses to pathogen (PAMPs) and damage-associated molecular patterns (DAMPs). Interestingly, the role for TREM2 was specific to females, suggesting a role for estrogens. Further studies with bone marrow-derived macrophages showed that TREM2 loss enhanced surface expression of Toll-like receptor 2 (TLR2), a key immune receptor that senses bacterial lipoprotein and lipoteichoic acid for proinflammatory activation. Cross-regulation between TREM2, TLR2, and estrogens in the context of infection has not been described. Methods Mouse background (8-10 week old C57BL/6) and S. aureus (USA300 LAC-13C) strains were identical for all studies. Craniotomy infection was induced by inoculating bone flaps with 103 CFU. In vitro studies used primary bone marrow-derived macrophages. Flow cytometry (surface markers, metabolism, ROS/RNS), Cytometric Bead Array (mediator production), and Western blot (protein quantification) were also used. Results Macrophages with individual knockouts of TREM2 and TLR2, and a double knockout of TREM2/TLR2, showed cross-regulatory effects from these receptors and 17β-estradiol on inflammatory surface markers, mediator production, metabolism, and reactive oxygen/nitrogen species production. Conclusion TREM2, TLR2, and estrogen appear to have an interconnected role in driving immune responses, which could be exploited for moderating pro- vs anti-inflammatory immune activation during S. aureus infection. Funding Source Preliminary work was supported by NIH F32NS126302 to Lee Korshoj and R01NS107369 and R01AI169788 to Tammy Kielian. Current work is supported by startup funds from the University of Nebraska Medical Center to Lee Korshoj. Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)

Tissue-specific clonal selection and differentiation of CD4+ T cells during infection 2306383

Abstract Introduction Pathogen-specific CD4+ T cells expand and contract during infection, giving rise to memory clones that shape future immunity. How distinct tissue environments influence the differentiation and clonal selection of polyclonal CD4+ T cells remains unclear, due in part to the difficulty of tracking pathogen-specific T cells in vivo. Methods To resolve tissue-dependent T cell fate decisions, we generated TRACK mice, a dual-recombinase fate-mapping system enabling precise temporal labeling of recently activated CD4+ T cells. TRACK mice were infected with influenza, and fate-mapped cells from lungs, mediastinal lymph nodes (medLNs), and spleen were analyzed by single-cell RNA-seq and paired TCR sequencing across effector and memory phases. Results Fate-mapping of influenza-specific CD4+ T cells in the TRACK mice revealed pronounced early clonal segregation across tissues, driven by organ-specific antigen availability and recruitment. Early TCR repertoires showed reduced clonal overlap across organs, indicating distinct local antigenic landscapes during the effector immune response. Effector CD4+ T cells exhibited tissue-specific differentiation, with spleen-derived cells acquiring a stem-like migratory phenotype, while medLN-derived cells preferentially became Tfh cells. Over time, tissues showed progressive clonal equilibrium, with increased overlap between lung- and medLN-derived clones. Memory CD4+ T cells also demonstrated converging antigen specificity, focusing on a narrower set of antigens despite maintaining early clonal distinctions. Conclusion These findings reveal that tissue environments impose early antigen-driven clonal segregation and guide distinct differentiation pathways, while memory formation promotes clonal redistribution and convergence of antigen specificity. TRACK mice provide a powerful system to resolve spatial regulation of T cell fate in vivo. Funding Source NIH, CZI, SNF, HHMI Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)

Identification and characterization of a novel long non-coding RNA targeting DUSP22 in T cells of human systemic lupus erythematosus patients 2253379

Abstract Introduction Systemic lupus erythematosus (SLE) is a chronic and incurable autoimmune disease. The protein levels of the TCR negative regulator DUSP22 (dual-specificity phosphatase 22) are significantly decreased in T cells from 55.8% SLE patients. Downregulation of DUSP22 in T cells results in hyperactivation of the kinase Lck, leading to T-cell-mediated inflammation and autoimmune diseases. The diagnostic power of DUSP22 downregulation in T cells for active lupus nephritis is even higher than those of existing clinical parameters (including serum anti-dsDNA antibody, C3, and C4 levels). The mechanism of DUSP22 downregulation in SLE T cells is unclear. Dysregulation of lncRNAs is associated with the progression of many diseases; however, the roles of T-cell lncRNAs in SLE pathogenesis remain unclear. Methods To identify the pathogenic T-cell lncRNAs of SLE (lncSLEs) that regulate DUSP22 levels in SLE T cells, RNAs isolated from T cells of SLE patients and healthy controls were subjected to transcriptomics. Results Forty six lncRNAs (lncSLE-1 to lncSLE-46) were differentially expressed in T cells of SLE patients. Among these 46 lncSLEs, 37 lncSLEs were significantly upregulated, and 9 lncSLEs were significantly downregulated. Interestingly, one downregulated novel lncRNA, lncSLE-3, showed a high calculated binding score to DUSP22 mRNA. Overexpression of lncSLE-3 induced DUSP22 mRNA and protein levels in Jurkat T cells. Moreover, sequence analysis showed that 6 miRNAs had putative binding sites on both DUSP22 mRNA and lncSLE-3. Overexpression of the two top-ranked miRNAs (miRNA-1 and miRNA-2) resulted in downregulation of DUSP22 mRNA and protein levels. Conclusion These results suggest that lncSLE-3 downregulation in SLE T cells induces miRNA-mediated DUSP22 degradation, contributing to T-cell-mediated autoimmune disease. Restoration of DUSP22 expression by overexpressing lncSLE-3 in T cells may be a novel therapeutic strategy for SLE nephritis. Funding Source n/a Topic Categories Basic Autoimmunity (BA)