Browse Articles

Liberalized Diets During Neutropenia: Ongoing Uncertainty in Hematopoietic Stem-Cell Transplantation

Reprogramming of Glioblastoma-Immune Crosstalk to Overcome Immunotherapy Failure 2258791

Abstract Introduction Glioblastoma multiforme (GBM) is a lethal brain cancer with a median survival of less than a year. Immunotherapies, such as immune checkpoint blockade (ICB), represent promising treatment options but still face challenges due to tumor resilience. Understanding how the brain and tumor environment shape immune responses is critical to overcoming therapy failure. GBM tumors are heterogeneous, with four subtypes: mesenchymal-like (MES), astrocyte-like (AC), oligodendrocyte-progenitor-like (OPC), and neural-progenitor-like (NPC), but their interactions with immune cells remain unclear. Here, this study aims to identify targetable GBM subtype-immune interactions that undermine ICB efficacy. Methods We applied Xenium spatial single-cell transcriptomics in an orthotopic GBM mouse model to achieve high-resolution mapping of spatial relationships between tumor and immune cell populations. We further employed small-molecule inhibitors to suppress mesenchymal (MES) subtypes and evaluate their synergistic efficacy with anti—PD-1 immunotherapy in vivo. Results Spatial transcriptomic profiling demonstrated that tumoricidal T cells and immunosuppressive tumor-associated macrophages (TAMs) were concentrated within mesenchymal-like (MES) GBM regions. Ligand—receptor mapping revealed that MES-like tumor cells and TAMs overexpress extracellular matrix proteins such as fibronectin (Fn1), which may hinder T-cell function. As the bromodomain-containing protein 2 (BRD2) complex drives the MES-like phenotype, its inhibition decreased Fn1 expression in GBM cells and, when combined with anti—PD-1 therapy, markedly prolonged survival in mice compared to anti—PD-1 treatment alone. Conclusion This study identifies a targetable molecular axis linking the BRD2 complex to fibronectin-driven immune suppression in mesenchymal-like GBM niches. By disrupting this pathway, BRD2 inhibition enhances the efficacy of immune checkpoint blockade, offering a promising combinatorial therapeutic strategy. Funding Source National Institute of Health Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Immune organ tertiary lymphoid structures (TLSs) as a therapeutic strategy for solid tumors 2247222

Abstract Introduction Tertiary lymphoid structures (TLSs) are linked to better patient outcomes and enhanced immunity in some cancers (e.g. ovarian, lung). TLSs support the reprogramming of immune system to attack the tumor and retain a long-term memory. We employed our previously published TLS-on-chip microfluidic device (TOD) and in vivo murine models to test a novel therapeutic formulation that involves engineering in situ TLSs to combat solid tumors. This formulation aims to generate effector T cells, memory B cells, and tumor-antigen-specific antibodies locally. Methods We integrated different cancer cell lines expressing varying levels of PD-L1/PD-L2 with healthy and cancer patients PBMCs in the TODs to quantify TLS formation, lymphocyte activation, and cancer cell killing. Based on the TOD’s composition, we defined a cellularized extracellular matrix gel to create TLS in vivo. To investigate the in vivo efficacy of this gel, we injected it peritumorally in a lung cancer cell line-derived xenograft (CDX) and a syngeneic model to monitor TLS formation and survival benefit measured by tumor volume reduction. Results TOD studies showed that with “hot” cancer cell lines (high PD-L1/PD-L2), our formulation induced TLS formation leading to a robust cytokine response, B cell activation, anti-tumor CD8+ T cell activity, and cancer cell death. In contrast, “cold” tumor cell lines suppressed TLS formation and the immune response. Peri-tumoral administration of the formulation successfully generated TLSs at the tumor site in a lung cancer CDX model in NSG mice. Intriguingly, they syngeneic lung cancer model showed reduced tumor volume and improved survival in the treated cohort. Conclusion Our findings demonstrate the feasibility of an injectable TLS therapeutic to overcome tumor-mediated immune suppression and generate a potent anti-tumor immune response. This approach has the potential to improve patient survival in challenging solid tumors. Further preclinical development of this promising therapy is ongoing. Funding Source ARPA-H Sprint for Women’s Health award Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Anti-inflammatory beta-carboline compounds in the commensal vaginal microbiome 2259583

Abstract Introduction The human vaginal microbiome can be broadly described as either Lactobacillus-dominant, low-diversity communities or Lactobacillus-low, high-diversity communities. While the presence of lactobacilli is associated with reduced inflammation and pro-inflammatory cytokines in the vagina, diverse communities lacking lactobacilli dominance are correlated with increased risk of inflammatory conditions. It is unclear how the health-associated lactobacilli actively promote the anti-inflammatory homeostasis of the vaginal mucosa. Methods We previously identified anti-inflammatory beta-carboline (BC) compounds in the supernatant of Lactobacillus bacterial culture, also present in cervicovaginal lavage of healthy people. We expand on our past findings, further evaluating anti-inflammatory activity of purified BC on fibroblast, endocervical, and macrophage cell lines. Currently, we are working toward elucidating mechanisms by which these compounds exert their anti-inflammatory effects in host cells by generating a CRISPRi endocervical reporter cell line. We are also investigating immune and microbial correlates of BC production with cytokine profiling and LC/MS. Results In addition to suppressing NFkB and ISG signaling downstream of multiple TLRs, we also observed suppression of cytosolic pathways, such as the cGAS-STING signaling pathway, and other cytokine receptors, including TNFa receptor. We observed cell type specificity in anti-inflammatory activity, with BCs suppressing type I interferon receptor activation in macrophages but not primary epithelial cells, however it is unclear if differential uptake of compound is responsible. Ongoing work focuses on identifying the genes required for this inhibition. Conclusion While there appear to be cell type specific differences in response to BC6, anti-inflammatory activity is broad, and the target of these compounds has yet to be uncovered. Ultimately, this work highlights a method by which vaginal commensal microbiome might maintain immune homeostasis. Funding Source NSF GRFP Topic Categories Mucosal and Regional Immunology (MUC)

Skeletal muscle as an active immune niche orchestrating adaptive responses to replicon RNA vaccination 2232181

Abstract Introduction Self-amplifying replicon RNA (repRNA) vaccines formulated with the cationic nanocarrier LION™ induce strong adaptive immunity with low systemic reactogenicity. However, the mechanisms linking localized intramuscular delivery to systemic T- and B-cell responses remain poorly understood. Methods We combined in vivo murine immunization models, engineered repRNA variants, flow cytometry, in situ hybridization, and in vitro muscle—APC—T cell co-culture systems to dissect interactions between transfected muscle cells, antigen-presenting cells (APCs), and lymphocytes. Results Intramuscular administration of repRNA/LION generated a muscle-resident immune niche. Transfected myocytes transferred RNA and protein antigens to infiltrating monocyte-derived dendritic cells, which cross-primed CD8+ T cells. Antibody induction required CD4+ T cells, which expanded locally and exhibited follicular helper—like features. CD138+ antibody-secreting cells accumulated in muscle, and their frequencies correlated with serum IgG titers. Conclusion Our findings reveal skeletal muscle as an active immunological hub rather than a passive site of antigen expression. Local antigen transfer and immune cell interactions orchestrate systemic T- and B-cell responses to repRNA/LION vaccination, providing mechanistic insights to guide safer and more durable RNA vaccine design. Funding Source NIH/NIAID grant R01AI180195, a Career Development Award from the American Society of Gene & Cell Therapy Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)

Efficacy of in-house vs. third party resources on medical student NBME style exam performance 2309816

Abstract Introduction As lecture attendance declines in medical school, many students adopt third-party educational resources as primary study tools. This study aims to determine if scores on National Board of Medical Examiners exams differ between students who rely on third-party resources and students who primary rely on in-house lecture material for studying. Methods Data was collected anonymously via survey from students in the Classes of 2026 and 2027 at California Northstate University College of Medicine. The survey assessed students’ primary study resources for NBME-style examinations, comparing reliance on third-party learning tools vs in-house lecture materials. Given the foundational role of immunology across multiple preclinical organ system blocks, this analysis is relevant to understanding how medical students prepare for immunology content within integrated curricula. Students were categorized into two groups based on their reported primary resource: in-house lecture users and third-party resource users. Students indicating equal use of both resource types were classified as in-house lecture users. Participants reported final course grades, which were converted to numerical values (Honors = 3, High Pass = 2, Pass = 1, Fail = 0) and averaged across courses for each student. Results The average numerical grades for the in-house lecture group (n = 6) + equal use (n = 8) (total, n = 14) and the third-party group (n = 61) were 2.37 and 2.19, respectively. The two groups’ average grades were compared using a Mann-Whitney U test in R version 4.3.2. The in-house lecture group had significantly higher average grades than the third-party group (p < 0.001). Conclusion Data suggests that students primarily using in-house lecture material achieve higher scores on average, compared to those who primarily rely on third-party material for NBME style exams. Future multi-institutional studies are needed to explore the factors that influence a student’s decision to utilize third-party resources. Funding Source n/a Topic Categories Immunology Education and Communication (EDU)

Clinical correlates of maternal antibody interference with oral rotavirus vaccine immunogenicity 2255869

Abstract Introduction Maternal antibodies (MatAbs) are critical for providing immune protection to neonates whilst their own immune responses are developing. Paradoxically, MatAbs can also interfere with the ability of neonates to respond to vaccination. This a major concern for rotavirus, a leading cause of gastroenteritis in infants for which vaccines are routinely administered at 6-8 weeks of age. We have recently demonstrated how MatAb interference with rotavirus vaccination is mediated by rapid vaccine clearance in a mouse model. Our current goal is to understand how MatAbs interfere with vaccine responses in human cohorts. Methods We analyzed infant serum samples from two vaccine clinical trials. We used the first cohort to evaluate how MatAbs are associated with vaccine immunogenicity, comparing pre-vaccination rotavirus-specific IgG titres between seroconverters and non-seroconverters. In the second cohort, protection from severe gastroenteritis following vaccination was documented. This allowed us to investigate the functional capacity of MatAbs to mediate vaccine clearance in the context of clinical outcome. Results Pre-vaccination rotavirus-specific IgG titres were significantly elevated in non-seroconverters compared to seroconverters, implicating MatAbs in vaccine failure. In the clinical outcome cohort, MatAb neutralization capacity against both extracellular and intracellular virus was significantly correlated with the risk of disease. Infants whose MatAbs pre-vaccination could robustly block virus replication before and after cell entry had increased risk of severe gastroenteritis when MatAbs had waned. Conclusion MatAb interference operates through multiple clearance mechanisms in human infants. MatAb characteristics predict both vaccine response and clinical outcomes. These findings provide mechanistic insights into vaccine underperformance in high-burden settings. This is valuable for developing strategies to overcome MatAb interference and optimizing vaccination schedules to maximize protection. Funding Source PATH, Affinito Stewart, Baker Institute for Animal Health Topic Categories Vaccines and Immunotherapy (VAC)

Resveratrol-regulated genes through miRNAs in the gut epithelial cells may play an important role in the gut health and amelioration of EAE in mice 2255889

Abstract Introduction Resveratrol (RES) is an anti-inflammatory, anticancer, and antioxidant compound found abundantly in red grapes, blue berries, peanuts, etc. Methods In this study, we investigated the effect of RES on gene expression in the gut epithelial cells of mice with EAE. To this end, epithelial cells from small intestine (SI) and colons of mice with EAE treated with vehicle or RES were isolated. Transcriptome arrays using total RNAs from epithelial cells of SI and colons were performed and data obtained from the arrays were analyzed using Transcriptome Analysis Console software. Results Results showed that there were 1,591 (1165 in SI and 426 in colon) genes that were up- or down-regulated (>2-fold) in the epithelial cells of mice with EAE treated with RES, when compared to vehicles. We selected two genes, α-defensin and Mucin 3, for further analysis. Upon analysis of their expression in the gut epithelial cells, α-defensin were downregulated while Mucin 3 was upregulated. To understand the regulation of these two genes in the gut, we investigated the role of microRNAs (miRs). There were two miRs, miR-378 and miR-338, that showed strong binding affinity with α-defensin and Mucin 3 respectively. Upon analysis of their expression in epithelial cells, miR-378 was upregulated but miR-338 was downregulated, demonstrating their possible role in the regulation of α-defensin and Mucin 3 genes. Conclusion Data obtained from this study demonstrates a possible role of miRs in the regulation of genes in the gut epithelial that may play a role in improving the health of the gut and amelioration of EAE in mice. Funding Source P30GM154631, P20GM103641, R01ES030144 and R01AI160896 Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)

You want me to use AI to write a research paper !? Teaching moments with generative AI to learn about autoimmune diseases in an Immunology course 2260145

Abstract Introduction The adoption of generative AI (GAI) in higher education has the potential to transform various educational practices in learning, teaching, and assessment. GAI offers increased accessibility and personalized learning, though the potential for inaccuracies, biases, and unethical use is of major concern. To educate students about these concerns, an assignment that required the use of GAI was implemented in a face-to-face Immunology course with mostly seniors in the class. Methods Students chose a specific autoimmune disease from a provided list and used any GAI source to generate a paper on the disease topic. The length of the paper, format and other specifics were indicated. Student learning was assessed using a rubric, which rated students’ effective integration and evaluation of GAI-generated content against peer-reviewed research articles, to demonstrate their critical thinking and synthesis skills, among other metrics. A 16-item survey about GAI utilization, contribution to learning, and ethical concerns was administered as part of the assignment. Results Data (n = 25) were analyzed, and free-response answers were thematically coded. While 86.9% of respondents found the GAI-generated content to be “very good” or “excellent,” 28.1% found inaccuracies, and 68% “strongly agreed” or “agreed” that GAI should be allowed to be used as a tool to complete academic assignments. Interestingly, however, only 28.1% “strongly agreed” or “agreed” that GAI may be used for assignments if not explicitly authorized by the instructor. Inaccuracies in the information provided were reported by 34.7% of the respondents. Conclusion Students noted concerns about not really learning the topic well. The lack of citations in GAI responses were also noted by many students. This assignment can easily be modified for different learning preferences and course environments. Raising awareness among students and faculty about the ethical use and limitations of GAI is crucial in today’s evolving pedagogical landscape. Funding Source n/a Topic Categories Immunology Education and Communication (EDU)

Defect Engineering of DNA Origami ROS Sensors for Portable Urinalysis

ABSTRACT Translating in situ dynamic changes of key signaling molecules into actionable clinical readouts remains a formidable challenge for noninvasive diagnostics. Here, focusing on reactive oxygen species (ROS) as pivotal signaling mediators, we developed defect‐programmed DNA origami ROS sensors (DOSs) for portable urinalysis of localized oxidative stress. Using triangular DNA origami (DO) nanostructures as two‐dimensional synthetic soft crystals, we programmed the number of discontinuity defects between adjacent staple strands and established a positive correlation between defect number and ROS‐triggered degradation kinetics. To transform this programmable degradation into a diagnostic function, we then engineered DOSs via orthogonal assembly of targeting and signaling modules onto DO. In a murine model of acute liver injury (ALI), DOSs selectively accumulated in the liver and underwent ROS‐triggered fragmentation into renal‐clearable debris, converting hepatic ROS levels into quantifiable urinary signals. Notably, this transformation efficiency depended positively on defect number in DOSs, enabling portable urinalysis that detected ALI onset at least 4 h earlier than conventional alanine aminotransferase (ALT) testing, with a maximum area under the curve of 0.94. This defect‐engineering strategy establishes a generalizable platform for early, noninvasive diagnosis of ROS‐related diseases.

Peripheral Measurable Residual Disease Activity Assessment by MALDI-TOF Mass Spectrometry in Patients With Newly Diagnosed Multiple Myeloma in the Phase III GMMG-HD7 Trial

Mass spectrometry (MS) offers a minimally invasive approach for detecting monoclonal proteins in multiple myeloma (MM), but large prospective evaluations remain limited. We analyzed 3,301 serum samples from 617 patients enrolled in the phase III GMMG-HD7 trial to characterize the analytical performance and clinical relevance of MS-based measurable residual activity. MS reliably distinguished therapeutic antibodies, tracked diagnostic M proteins longitudinally, and demonstrated strong prognostic value across defined time points. MS negativity was associated with superior progression-free survival (PFS), with the greatest separation at later time points (12 months of maintenance: hazard ratio, 0.25 [95% CI, 0.15 to 0.43]; adjusted P < .001). Combined assessment with bone-marrow measurable residual disease (MRD) further refined risk stratification: MS/MRD double-positive patients exhibited the worst PFS, whereas all other groups showed comparably favorable outcomes. MS/MRD concordance increased over time and was influenced by immunoglobulin isotype, with expected immunoglobulin G-recycling–associated early discordance. MS provided accurate M-protein detection and outperformed serum protein electrophoresis at low concentrations, reliably quantifying low-level residual disease. These findings establish serum MS as a sensitive, reproducible, and practical biomarker that complements MRD and supports minimally invasive disease monitoring in MM, with potential integration into future response assessment and risk-adapted treatment strategies.

T-bet CAR T cells: A new avenue for NSCLC therapy analyzed in lung cancer-derived organoids 2258880

Abstract Introduction Chimeric antigen receptor (CAR) T cell therapy in solid tumors is limited by the immunosuppressive tumor microenvironment (TME). Since we have identified T-bet as a strong anti-tumor candidate, we thought to explore new therapies against NSCLC by developing next-generation CAR T cells and patient-derived lung cancer organoids (PDOs) as a clinically relevant preclinical platform for evaluating CAR T cell antitumor efficacy. Methods To explore strategies that improve CAR T cell efficacy and persistence, we first characterized T cells in the lung tumor environment by flow cytometry. Next, we cultured PBMCs and purified CD3+ T cells from patients with NSCLC with IL-2 or IL-2+ IL-12 to assess the changes in T-bet expression in vitro. We thus engineered B7-H3 (CD276) directed CAR T cells co-expressing either IL-12 or the transcription factor T-bet (TBX21). Simultaneously, patient-derived organoids were established from lung cancer tissues to preserve tumor heterogeneity and architecture as a clinically relevant platform for CAR T cell antitumor efficacy evaluation. Results Here we found low levels of Th1 T-bet + T cells in patients with NSCLC as compared to healthy controls. Moreover, in PBMCs under IL-2+ IL-12 stimulation, we found a significant expansion of CD3+CD4+ T-bet+ T cells. Preliminary data indicate that IL-12—armored CAR T cells exhibited the highest anti-tumor effect against the lung adenocarcinoma cell line A549, but raised concerns about systemic toxicity as confirmed in in vitro observations. In contrast, T-bet—modified CAR T cells displayed stronger CAR T cell survival and expansion associated with significant antitumor response. Conclusion This study leverages PDOs as a clinically relevant preclinical model to optimize CAR T design and supports T-bet as a promising axis for developing safer and more durable next generation CAR T therapies against NSCLC. Funding Source n/a Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Defining the Primary Immune Cell in the Immune Response to Coagulation Factor VIII 2245246

Abstract Introduction Hemophilia A is an X-linked bleeding disorder caused by mutations in the F8 gene, leading to a deficiency of coagulation factor VIII (FVIII). However, FVIII infusions for the treatment of bleeding triggers the development of neutralizing FVIII antibodies in about 30% of patients with severe hemophilia A, rendering FVIII replacement therapy ineffective. Although several studies have demonstrated that various immune cells, such conventional dendritic cells (cDCs), macrophages, monocytes, and marginal zone B cells, co-localize or interact with FVIII, the primary immune cell population mediating FVIII immune recognition remains poorly explored. DCs endocytose and process FVIII into peptides, which are then recognized by CD4+ T cells that activate B cells to produce anti-FVIII antibodies. We hypothesize that type 2 cDCs (cDC2) mediate FVIII recognition and CD4+ T cell activation that enhances FVIII immunity. Methods Batf3⁻/⁻ mice (cDC1 knockout [KO]), Zeb2-Delta3⁻/⁻ mice (cDC2 KO), and Zbtb46-DTR mice without diphtheria toxin depletion (WT) were utilized to isolate bone marrow-derived dendritic cells (BMDC). Results Immature BMDC endocytosed more FVIII than mature and intermediate-mature BMDC as expected. However, immature BMDC from cDC2 KO mice exhibited reduced FVIII uptake compared to those from WT and cDC1 KO mice. Although BMDC from cDC2 KO mice enhanced CD4+ T cell proliferation compared to WT mice, cDC2 KO mice treated with FVIII exhibited reduced anti-FVIII antibodies than WT mice. Conclusion Together, these data suggest that cDC2 predominantly contributes to FVIII-specific adaptive immunity through FVIII uptake and promotion of CD4+ T cell proliferation. Funding Source K99 Topic Categories Immune Mechanisms of Human Disease (HUM)

Spatial Transcriptomics Reveals Immune Remodeling in Recurrent Oligodendroglioma 2259684

Abstract Introduction Oligodendrogliomas frequently recur despite standard therapy, but how the immune microenvironment evolves during recurrence remains poorly understood. Methods Visium Spatial Transcriptomics data from primary and matched recurrent oligodendrogliomas from 14 patients were processed using SpaceRanger and deconvoluted with SpaCET’s low-grade glioma model to estimate cell-type proportions. Cell-type fractions were normalized using Centered Log-Ratio transformation and clustered (k = 5, Euclidean distance) to define reproducible spatial niches. Immune subset distributions were compared between primary and recurrent tumors to assess niche-specific remodeling, with propensity score matching applied to control for baseline clinical and molecular differences between treated and untreated patients. Results Five spatial niches were identified, including immune-enriched perivascular and infiltrative regions. Recurrent tumors showed marked loss of adaptive immunity, with downregulation of CD4+ T-helper subsets (Th1, Th2, Th17, Tfh; log₂FC ≈ —3) and total CD4+ T cells (—2.9). This loss, most pronounced after radiation and/or chemotherapy, indicates therapy-associated collapse of adaptive immune niches. Macrophage and microglial populations were preserved or increased, reflecting a shift toward a myeloid-dominant, immunosuppressive microenvironment. Immune-rich perivascular regions exhibited depletion of T-helper diversity and enhanced myeloid signaling, consistent with immune exclusion and vascular remodeling. These findings persisted after propensity score matching, with treated tumors remaining enriched for immunosuppressive niches (p < 0.05). Validation by Xenium spatial transcriptomics and CODEX multiplex imaging will be included in the final presentation. Conclusion Recurrent oligodendrogliomas exhibit collapse of adaptive immune niches and expansion of myeloid-dominant regions, defining immune remodeling as a hallmark of recurrence and myeloid-driven immunosuppression as a potential therapeutic target. Funding Source n/a Topic Categories Computational and Systems Immunology (COMP)

ST8SIA4-mediated polysialylation promotes CD8+ T cell infiltration in melanoma 2246376

Abstract Introduction Immune checkpoint inhibitors (ICIs) have revolutionized melanoma treatment. However, about half of patients still face disease progression. ICI efficacy depends on tumor-infiltrating lymphocytes, particularly CD8+ T cells. Understanding genes that influence CD8+ T cell infiltration is critical for improving and predicting ICI responses. Here, we investigate ST8SIA4, a sialyltransferase that synthesizes polysialic acid(polySia). Our data suggest ST8SIA4 influences the tumor microenvironment (TME) toward a hot tumor. Methods To better understand determinants of tumor immune infiltration, we examined TCGA-SKCM data utilizing Tumor Immune Estimation Resource, grouping samples by CD8+ T cell infiltration. SurfaceGenie was used to prioritize proteins that localize to the cell surface or contribute to surface modifications. Based on in silico data, we created a murine melanoma cell line inducibly expressing ST8SIA4. Immune infiltration was assessed in vitro using spheroid co-cultures with syngeneic CD8+ T cells and in vivo with high-dimensional flow cytometry-based immune phenotyping. Siglec binding was assessed by flow cytometry using Siglec FC chimera. Results In silico analysis revealed 43 genes upregulated in high CD8+ T cell tumors. Among these, ST8SIA4 had the highest correlation with survival. Further analysis shows that ST8SIA4 expression is elevated in patients responsive to ICIs, including PD-1 and CTLA-4 inhibitors. Spheroid co-cultures with syngeneic CD8+ T cells indicate more immune infiltration when melanoma spheroids are expressing ST8SIA4. Furthermore, in vivo analysis suggests that ST8SIA4-expressing melanomas recruit more CD45+CD8+ and CD45+NK1.1+ populations compared to parental tumors. Our preliminary in vitro data suggest this phenotype is Siglec-independent in murine cell lines and potentially mediated by other immune regulatory factors. Conclusion These findings suggest ST8SIA4-mediated polySia modulates TME immune population and can be a potential biomarker for ICI response. Funding Source n/a Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

EQ504, a Potent AhR Modulator, Promotes Epithelial Repair and Barrier Restoration Compared to Clinically Validated AhR Agonists 2309900

Abstract Introduction The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that integrates environmental signals to regulate intestinal immune homeostasis and epithelial barrier integrity. In inflammatory bowel disease, AhR modulators have shown clinical benefit partly through induction of IL-22, which enhances epithelial repair and barrier function. However, differences in the epithelial-directed activity and functional outcomes of AhR-targeting agents remain poorly defined. EQ504 is a novel, potent small-molecule AhR agonist being developed for the treatment of ulcerative colitis to promote mucosal healing. Methods AhR activation was evaluated in HepG2 cells using the EROD assay. Epithelial repair was assessed in T84 human intestinal epithelial cells using in vitro scratch wound healing assays. Expression of epithelial barrier-related genes was quantified in T84 cells at matched compound concentrations. Ongoing studies include transepithelial electrical resistance measurements and human intestinal organoid models. Results EQ504 induced robust, dose-dependent AhR activation, and was ∼10-fold more potent than the clinically validated AhR agonist obefazimod in the EROD assay. Functionally, EQ504 significantly accelerated epithelial wound closure in scratch assays, whereas obefazimod showed minimal or no effect under equivalent conditions. At matched concentrations, EQ504 increased expression of the IL-22 receptor subunit IL22RA and reduced expression of the pore-forming tight junction protein claudin-2 (CLDN2), consistent with enhanced epithelial repair, which were not observed with obefazimod. Conclusion These findings demonstrate that EQ504 is a potent AhR agonist with superior epithelial repair and barrier-stabilizing activity compared to obefazimod. The ability of EQ504 to promote IL-22 responsiveness while reducing CLDN2 expression highlights functional differentiation among AhR-targeting therapies and supports its development as a promising treatment for inflammatory mucosal diseases. Funding Source n/a Topic Categories Mucosal and Regional Immunology (MUC)

SHMT2 Regulates T Cell Homeostasis and Mucosal Inflammation Via Metabolic and Lipid Remodeling 2256280

Abstract Introduction Serine hydroxymethyltransferase 2 (SHMT2) is a mitochondrial enzyme essential for one-carbon metabolism, nucleotide biosynthesis and redox balance supporting cell proliferation and survival. While SHMT2 is required for the effector CD8+T cells expansion following infection, its role in CD4+T cell development, differentiation and Treg function under inflammatory conditions remains undefined. Methods We generated T cell-specific (Shmt2fl/flCD4Cre) and Treg-specific (Shmt2fl/flFoxp3YFPCre) conditional knockout (cKO) mice. T cell developmental and homeostatic phenotype were characterized by flow cytometry, and Th subset differentiation was assessed in vitro and in vivo, while Treg function was tested using naïve CD4+ T cell transfer in Rag⁻/⁻ recipients. Untargeted metabolomics and lipidomics were performed by mass spectrometry. Results SHMT2-deficient T cells developed normally in the thymus but displayed CD44high memory-like phenotype at the periphery. SHMT2 deletion in T cells impaired Th1, Th2, and Th17 differentiation, whereas induced Treg development remained unaffected. Upon house dust mite challenge, Shmt2CD4-cKO mice exhibited reduced eosinophilia, Th2 cytokines and serum IgE. In contrast, Shmt2Treg-cKO mice showed elevated lung infiltration of eosinophils, neutrophils, and T cells, with increased Th2/Th17 cytokines and serum IgE. Despite increased Treg frequencies, Shmt2Treg-cKO Tregs failed to suppress mucosal inflammation in Rag-/- mice, suggesting that SHMT2 is dispensable for Treg development but required for Treg suppressive function. The loss of SHMT2 in T cells disrupted mitochondrial one-carbon metabolism, induced redox imbalance and enhanced neutral lipid storage and phospholipid synthesis, with compensatory arginine-proline upregulation and taurine depletion to sustain survival under oxidative stress. Conclusion SHMT2 maintains T cells metabolic fitness and Treg regulatory function, highlighting SHMT2-dependent metabolic pathways as a therapeutic target in mucosal inflammation. Funding Source 2024 Hevolution/AFAR New Investigator Award Topic Categories Mucosal and Regional Immunology (MUC)

Role of Periodontitis in Inflammatory Bowel Disease 2256065

Abstract Introduction Periodontitis is a prevalent oral infection linked to the initiation/exacerbation of inflammatory bowel disease (IBD), yet its causal and mechanistic basis remains unclear. We sought to elucidate how periodontitis contributes to IBD pathogenesis through integrated clinical and animal studies. Methods We conducted a case-control clinical study assessing the periodontal status of 180 IBD patients and 180 healthy controls. Each subject underwent a comprehensive oral examination and provided saliva and fecal samples. To mimic human conditions, we induced periodontitis in mice using ligature-induced periodontitis (LIP) and oral gavage models, utilizing mice with genetic gut barrier defects or gut barrier weakened by piroxicam medication. Results IBD patients exhibited prevalence of periodontitis compared to healthy controls. Severe periodontitis, bleeding scores were positive risk indicators for IBD. 16S rRNA sequencing identified the presence of oral taxa in the feces of IBD patients with periodontitis compared to healthy controls. Corroborating these human findings, LIP in mice facilitated the colonization of native oral bacteria in the intestine, leading to colitis. Similarly, oral gavage of human periodontal pathogens induced colitis in mice with gut barrier deficiencies, compared to untreated mice or those inoculated with oral commensals. Periodontal pathogens promoted infiltration of IgG+ B cells into the colonic lamina propria and increased IgG activation, triggered elevated IL1b and IL-17 production, leading to induction of colitis. Remarkably, the resolution of LIP in mice diminished the intestinal load of oral bacteria and reversed colitis in mice. Conclusion The oral cavity may serve as a reservoir for bacteria that can induce colitis via B-cell-mediated responses, especially in the presence of compromised intestinal barriers. Dental care can reduce the risk of IBD by limiting the influx of colitogenic oral pathogens and should be considered as an integral part of IBD evaluation and care. Funding Source n/a Topic Categories Mucosal and Regional Immunology (MUC)

ATP Mediated Mast Cell Activation is Female Dominant 2260259

Abstract Introduction Allergic diseases are more common in women than men. The explanation for this dimorphism is only partly understood. ATP is a damage associated molecular pattern (DAMP) that is elevated in allergic asthma. Mast cells are central to allergic inflammation and are central to DAMPs. We tested the hypothesis that female mast cells mount stronger responses than male mast cells when stimulated with ATP. Methods We cultured bone marrow derived mast cells from C57BL/6, C3HeJ, and BALB/c mice. Cells were stimulated with ATP, or ATP derivatives and mast cell cytokine responses were measured by ELISA and flow cytometry. Results ATP elicited greater cytokine release and degranulation in female mast cells than in male mast cells. This was not due to a difference in the expression of the ATP receptor, P2X7 between males and females. Because ATP has a short half-life, we tested the non-hydrolysable isoforms ATPγS and ADPβS, as well as adenosine. None of these ATP derivatives yielded a sexually dimorphic response. The dimorphic ATP response could therefore be due to differences in the rate of ATP degradation. In support of this hypothesis, male BMMCs express higher levels of the ATP degrading enzyme CD39. Conclusion Our data supports the hypothesis that female mast cells mount a stronger response to ATP. This difference may be due to female mast cells degrading ATP at a slower rate. Funding Source 1R01AI164710 Topic Categories Immediate Hypersensitivity, Asthma, and Allergic Responses (HYP)

Continuous‐Conductivity‐Gradient All‐Organic Aerogels with Machine‐Learning‐Assisted Design toward Ultrabroadband, Ultralow‐Reflection Electromagnetic Shielding

ABSTRACT Ultralow‐reflection electromagnetic interference (EMI) shielding across broad frequency ranges remains elusive as low reflection and low transmission are rarely achieved simultaneously, particularly in lightweight aerogels amenable to scalable manufacturing. Here, a continuous‐conductivity‐gradient (CCG) aerogel with machine‐learning (ML)‐assisted optimization is developed via diffusion‐controlled in situ oxidative polymerization of pyrrole within an as‐prepared, mechanically resilient porous aramid nanofiber scaffold, followed by an energy‐efficient, scalable ambient‐pressure‐drying strategy. The resulting CCG aerogel integrates a continuous through‐thickness gradient of polypyrrole (PPy) with a highly porous architecture, enabling a smooth impedance transition and progressive bulk microwave attenuation for ultrabroadband, ultralow‐reflection EMI shielding. The optimized CCG aerogel delivers an effective absorption‐dominated frequency bandwidth of 29.76 GHz spanning 10.24–40 GHz, with an EMW reflectivity below 0.1, while maintaining an EMI shielding effectiveness above 40 dB across the ultrabroadband frequency range of 8.2–40 GHz, surpassing the shielding performance of existing EMI shielding materials. Mechanistic analyses reveal that the continuous gradient couples efficient front‐surface impedance matching with progressive internal dissipation, thereby circumventing the impedance discontinuities inherent to discrete multilayers. Overall, this ML‐assisted strategy integrates novel electromagnetic and structural design with robust, scalable all‐organic aerogel manufacturing, offering a general platform for ultrabroadband, ultrahigh‐absorption, ultralow‐reflection EMI shielding across diverse material systems.