Citations

Aging is a major risk factor for increased morbidity and mortality following acute respiratory virus infections. To elucidate the immune determinants underlying viral pathogenesis and delayed lung repair in the aged lung, a comprehensive time-course study was conducted. Single-cell RNA sequencing (scRNAseq) and high-dimensional flow cytometry were utilized to compare lungs from young and aged mice infected with influenza A virus (IAV). Aged hosts displayed diminished alveolar macrophage (AM) and dendritic cell (DC) but elevated monocyte-derived macrophage (MoM) and interstitial macrophage (IM) presence following infection. Additionally, enhanced accumulation of adaptive immune cells, including CD4+ tissue-resident helper (TRH) cells, CD8+ tissue-resident memory (TRM) cells, and a B cell subset resembling age-associated B cells, was observed in the memory phase. Pathway analysis revealed that elevated type I and II interferon (IFNα/γ) signaling, especially in MoM/IM subsets, distinguished the aged hosts from the young. Inhibition of IFNα/γ signaling after viral clearance improved long-term respiratory outcomes and reduced both IM and TRH populations in aged mice. These findings highlight the pivotal role of IFNα/γ signaling, likely within MoM/IM subsets, in driving the exuberant persistence of adaptive immune cells and chronic immunopathology in the aged lung following acute viral infection.

Aging is a major risk factor for increased morbidity and mortality following acute respiratory virus infections. To elucidate the immune determinants underlying viral pathogenesis and delayed lung repair in the aged lung, a comprehensive time-course study was conducted. Single-cell RNA sequencing (scRNAseq) and high-dimensional flow cytometry were utilized to compare lungs from young and aged mice infected with influenza A virus (IAV). Aged hosts displayed diminished alveolar macrophage (AM) and dendritic cell (DC) but elevated monocyte-derived macrophage (MoM) and interstitial macrophage (IM) presence following infection. Additionally, enhanced accumulation of adaptive immune cells, including CD4+ tissue-resident helper (TRH) cells, CD8+ tissue-resident memory (TRM) cells, and a B cell subset resembling age-associated B cells, was observed in the memory phase. Pathway analysis revealed that elevated type I and II interferon (IFNα/γ) signaling, especially in MoM/IM subsets, distinguished the aged hosts from the young. Inhibition of IFNα/γ signaling after viral clearance improved long-term respiratory outcomes and reduced both IM and TRH populations in aged mice. These findings highlight the pivotal role of IFNα/γ signaling, likely within MoM/IM subsets, in driving the exuberant persistence of adaptive immune cells and chronic immunopathology in the aged lung following acute viral infection.

Immune checkpoint inhibitors (ICIs) can cause immune-related adverse events (irAEs), with acute interstitial nephritis (ICI-AIN) being the most common irAE. While the exact mechanism remains unclear, upregulation of IFN-γ and TNF-α pathways has been implicated. This study used a humanized chimeric PD-1/PD-L1 mouse model to assess renal effects of ICIs, alone or combined with proinflammatory cytokines, and to test if selective TNF-α blockade could prevent ICI-AIN. Mice were randomly divided into 4 experimental groups: Control, ICI-Only, ICI-Cytokines (ICI-Cyt), and ICI-Block (ICI-TNF-α blockade). Renal function and cytokine profiles were assessed, while kidney tissue was analyzed using microscopy and single-cell RNA-seq. Histology revealed increased renal infiltration of CD4 + /CD8 + T cells in ICI-treated groups and decreased TNF-α expression following TNF-α blockade. Additionally, kidney tissue ELISA demonstrated reduced IFN-γ levels following TNF-α blockade. Plasma IL-6, MCP-1, and TNF-α were lower in ICI-Block mice. Single-cell RNA-seq revealed shifts in immune cell populations and genes of interest including Bcl2a1 , Icos , Il18r1 , Ccr2 , and Jaml . This humanized model replicates ICI-AIN key features, revealing a synergistic role of ICIs and proinflammatory cytokines. TNF-α blockade demonstrated protective effects, supporting its potential role in mitigating the risk of ICI-AIN.

Abstract Pancreatic ductal adenocarcinoma (PDAC) is unresponsive to immune checkpoint therapies largely due to immunosuppression mediated by myeloid and lymphoid cells. Effective treatment strategies require, in addition to immune stimulation, the depletion of these immunosuppressive cells and their interactions. Here, we demonstrate for the first time, that a single verteporfin-based photodynamic therapy (PDT) treatment triples median survival in a KPC-PDAC model when combined with anti-PD1 therapy. Mechanistically, apart from reducing CK19 + tumor cells, PDT depletes immunosuppressive myeloid (CD11c+) and lymphoid (FOXP3+) cell populations, by ~ 4- and ~ 18.4-folds, respectively. PDT further disrupts interactions between these immunosuppressive cells, attenuating a key immune-tolerance axis. At the systemic level, PDT reduces splenic immunosuppression through modulation of tumor-derived cytokines. Within this reprogrammed immune-landscape, anti–PD-1 therapy elicits robust CD8 + T-cell responses, reflected by an ~ 6.7-fold increase in the intratumoral CD8+/Treg ratio. Collectively, these findings establish verteporfin-PDT as an immune-priming strategy that complements anti–PD-1 therapy by alleviating immunosuppression in PDAC.

Abstract Although CD8+ T cells face intense immunosuppressive and metabolic pressures within the tumor microenvironment (TME), a subset of these cells can mount resilient responses to immune checkpoint inhibitor (ICI) therapy. We recently identified a population of such resilient CD8+ T cells in patients with advanced solid tumors who were unresponsive to standard-of-care cancer therapies but showed clinical benefit from ICI or combination ICI therapy. Among these resilient CD8+ T cells, which retain their cytotoxic capacity to eliminate tumor cells, we observed upregulation of ME1 and downregulation of DUSP2 in responders to the combination therapy. However, the mechanistic role of altered ME1 and DUSP2 expression in shaping resilient CD8+ T cell responses in cancer remains to be fully elucidated. To that end, we used scRNA-seq, bulk RNA-seq, and ATAC-seq analyses to investigate how altered expression of DUSP2 and ME1 regulates transcription of genes encoding effector molecules in both human and mouse CD8+ T cells. Additionally, we utilized CD8+ T cell-specific DUSP2 knockout (KO) and ME1 transgenic (Tg) mouse models to define the roles of these genes in effector T cell differentiation and antitumor responses in vivo. We found that DUSP2 downregulation enhances the expression of effector molecules (e.g., GZMB and NKG7) in CD8+ T cells, accompanied by increased cytotoxic activity. Mechanistically, reduced DUSP2 expression promotes chromatin accessibility at effector gene loci by modulating the nuclear residency balance between BAF and NuRD, two chromatin remodeling complexes with opposing functions. In parallel, ME1 overexpression enables activated CD8+ T cells to bypass the classical glycolysis pathway in favor of the pentose phosphate pathway (PPP), thereby boosting ATP production while minimizing excess ROS accumulation and increasing effector molecule expression via an epigenetic mechanism. Our study reveals a previously unknown adaptive mechanism by which resilient CD8+ T cells maintain their cytotoxic function within the TME. This is achieved through integrated reprogramming of epigenetic regulation and metabolic fitness, enabling compensation for metabolic stress in the TME and restoration of responsiveness to ICI-based combination therapy, even in patients with substantial tumor burden. Citation Format: Haidong Dong. Epigenetic and metabolic reprogramming for resilient CD8+ T cell responses in the tumor microenvironment [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr A001.

Abstract Chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable response rates in relapsed/refractory aggressive B-cell non-Hodgkin's lymphoma. However, durable remissions occur in only 40% of treated patients, highlighting mechanisms of therapeutic resistance and immune escape. While cytotoxicity is principally executed by CAR T-cells, monocytes shape CAR-T cell efficacy and orchestrate cytokine-driven immunity. In this study, we defined distinct metabolic profiles of T-cell and monocyte subsets based on clinical response. Single-cell RNA sequencing (scRNA-seq) and T-cell receptor sequencing (scTCR-seq) were performed on peripheral blood mononuclear cells at three timepoints: before lymphodepletion (BL), at peak CAR-T expansion (PK), and one-month post-infusion (M1). Data were processed with CellRanger v7.0.1 and analyzed with the immunopipe pipeline (Wang et al., 2025). Seurat v4.3.0 was utilized for unsupervised hierarchical clustering analysis; subsets identified included classical monocytes (CM), intermediate monocytes (IM), non-classical monocytes (NM), and monocytic myeloid derived suppressor cells (mMDSC). Metabolic profiles were compared across patients achieving ≥6-month complete remission (CR, n=16), primary refractory disease (PD1, n=4), or relapsed after a prior response (PD2, n=12). A total of 107035 T cells and 129981 monocytes from 77 serial samples in 32 patients were analyzed. CR patients had a higher T-cell:monocyte ratio than PD1/PD2 at all time points, especially at BL and PK (BL 1.2 vs 0.4, p=0.011; PK 1.3 vs 0.3, p=0.027). Clinical responses were compared with metabolic pathway analysis and identified oxidative phosphorylation (OXPHOS) as the dominant pathway. OXPHOS was consistently enriched in PD cohorts across T-cell subsets, particularly in PD1 vs CR at BL (mucosal-associated invariant T-cell (MAIT) and T peripheral memory (Tpm)), and at PK (CD4/CD8 memory precursor effector cells (MPEC) and activated MPECs (MPECa), CD4 T-helper 1 proliferating (Th1p), CD4 Th2 activated (Th2a), regulatory T-cell (Treg), CD8 naive senescent (CD8NS), CD8 T effector memory (Tem) tumor recirculating (TR), CD8 Tpm, CD8 T resident memory (Trm) TR and MAIT Tpm). By M1, OXPHOS enrichment in CD4/CD8MPECa, CD4Th2a, CD8NS, CD8TemTR reversed, now predominant in CR although CD8Tpm and CD8TrmTR remained enriched in PD1. In the monocyte subsets at BL, PD2 showed OXPHOS enrichment in CD163+ monocytes (mono), IM IL1, mMDSC SIRPA, mMDSC TGFβ, and CM IL6 subsets compared to PD1 and CR, while PD1 showed OXPHOS enrichment in IM CD38, CM TGFβ, and mMDSC HIF1A vs CR and PD2. This persisted at PK. By M1, the pattern reversed and mirrored that of T-cells, with CR patients showing OXPHOS enrichment in CD163+mono, CM IL6, CM TGFβ, IM CD38, mMDSC HIF1A, mMDSC SIRPA and mMDSC TGFβ, and additionally in CM EMT, CM p53, NM, NM CD36 vs PD1/PD2. Glycolysis/gluconeogenesis (GLY) was also enriched across subsets. In T-cells, PD1 vs CR showed GLY enrichment in CD4Th2a, CD8Tpm, CD8Tpm proliferating and MAIT Tpm at PK. In monocytes, GLY was enriched in PD1/2 vs CR at BL (CD163+mono, CM IL6) and PK (CD163+mono, IM CD18, mMDSC SIRPA). By M1, GLY metabolism was enriched in CR vs PD1/PD2 in CD163+mono, CM IL6, mMDSC SIRPA. Additional GLY enriched subsets at CR vs PD1 included CM, CM p53, EMT, IM CD38, IM IL1, mMDSC HIF1A, NM, NM CD36. Inositol phosphate metabolism (IP) was predominantly enriched in PD2 vs CR at BL (CD8NS, CD8Tcm, CD8Tpm activated), PK (CD4Th2, CD8NS, CD8Tem TR, CD8Tpm proliferating, γδT Tem) and M1 (CD4/CD8 MPECa, CD4 Th1/Th2, CD8NS, CD8Tpm, CD8 Tpm proliferating, Treg and MAIT Tpm). Notably, Treg was the only T-cell subset enriched for IP at PK in CR vs PD1/PD2. Additionally, the TCA cycle was enriched in PD1 Tregs and Th2 cells at BL and PK vs CR/PD2. A higher T-cell:monocyte ratio in CR vs PD1/PD2 supports prior evidence that elevated pre-lymphodepletion lymphocyte:monocyte ratios predict better outcomes. We identified distinct metabolic signatures in T-cells and monocytes between CR and PD1/PD2. OXPHOS enrichment in T-cells and monocytes at M1 in CR patients may reflect oxidative programming as a hallmark of sustained anti-tumor immunity. Conversely, GLY enrichment in PD1 T-cells at PK may reflect short-lived effector states lacking persistence. Overall, these findings highlight metabolic profiling as a promising predictive biomarker and therapeutic programming target to enhance CAR T-cell outcomes.

Abstract Description CD8 T cell programming creates a pool of naïve, effector, memory, or exhausted subsets, however the regulation of these trajectories is not expansively elucidated and has serious implications for cancer immunity and immune checkpoint inhibitor (ICI) therapy. We found a significant decrease of Dual Specificity Phosphatase 2 (DUSP2) in CX3CR1+ CD8s, a highly resilient subset, from ICI responders. Thus, we hypothesized that DUSP2 negatively regulates CD8 T cells in responses to ICI therapy. DUSP2 knockdown (KD) statistically improved CD8 cytotoxicity and expression of NKG7, a vital effector molecule. DUSP2 KD also increased SMARCA4 expression, a BRG/BRM-associated factor (BAF) complex ATPase, and increased open chromatin regions of BAF components. BAF complexes are chromatin remodelers implicated in CD8 differentiation pathways. In line with this, we found CD8s from DUSP2 conditional knockout (cKO) mice demonstrated a trend in defective memory generation. DUSP2 cKO CD8s also trended towards decreased PD-1 and increased CX3CR1 expression, demonstrating a more effector like phenotype. DUSP2 cKO mice did not show a significant difference in tumor protection in-vivo, presumably due to skewing of CD8 fates via BAF. Promisingly, DUSP2 KD increased ex-vivo cytotoxic functionality in about 50 percent of tested cancer patient PBMCs. Adjuvant BAF inhibition with DUSP2 KO versus KD in a specific CD8 subset may enhance responses further, providing a novel avenue for improving ICI efficacy. Funding Sources Supported by NCI 1F31CA287495-01 Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)

Abstract Description Combination of radiotherapy (RT) and immunotherapy has gained popularity to turn up the heat on cold tumors. However, intrinsic resistance is prevalent, hence better therapeutic strategies are needed to improve the outcome of patients. We recently demonstrated in metastatic prostate cancer that circulating levels of tumor-derived extracellular vesicles (tdEVs) increased shortly after RT and was associated with poor survival. TdEVs are mediators of antitumor immunity but their role in response to RT remains unknown. Our study elucidates the impact of RT on immunomodulatory roles of tdEVs. Mouse tumors models expressing a bioluminescent EV reporter were treated with clinically used doses of RT. TdEV organotropism was measured by ex-vivo imaging at different timepoints. TdEVs were detected in blood, spleen, lymph nodes and immune cells. OT-1 transgenic mice and in vitro co-culture assays showed a reduction in CD8 T-cell cytotoxic activity in presence of tdEVs from irradiated cells. To identify key players of tdEV-mediated immunosuppression in response to RT, proteomic analysis revealed the immune checkpoint molecule B7-H3 was overexpressed in tdEVs after irradiation. Genetic deletion of B7-H3 inhibited the suppressive activity of tdEVs from irradiated cells resulting in enhanced T-cell cytotoxicity. This study describes tdEVs as a mediator of systemic immunosuppression in response to radiotherapy and B7-H3 as a potential therapeutic target to boost antitumor immunity. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description Therapies targeting the PD-1/PD-L1 axis are among the leading treatments of cancer, but only a minority of patients benefit. Many therapies focus on preventing PD-L1 from binding to its receptor, PD-1, but do not address PD-L1’s ability to be recycled to the cell surface and any intrinsic functions it may possess. Our lab has developed an antibody (H1A) that binds to PD-L1 and prevents its association with a stabilizing protein, CMTM6, therefore targeting it for lysosomal degradation. Consequently, H1A limits any PD-L1 intrinsic function while also decreasing interactions with PD-1. Here, we use human-derived immune cells to test H1A’s effect on immune responses through flow cytometry, multiplex screening, and cytotoxicity assays. Additionally, we have developed a humanized PD-1/PD-L1 mouse model that allows us to test H1A’s effect on tumor growth inhibition in an immunocompetent host. Our results show that H1A specifically targets human myeloid cells, resulting in increased co-stimulation, antigen presentation, and cytokine secretion. H1A demonstrated enhanced T cell cytotoxicity in a whole PBMC culture. Finally, H1A resulted in greater tumor growth inhibition and survival in our in vivo tumor models. This work highlights the importance of targeting beyond PD-1/PD-L1 ligation and that myeloid cells are instrumental to enhancing the immune response against cancer. H1A is emerging as a new immunotherapy tool to target PD-L1 and CMTM6 in myeloid cells for treatment of cancers. Funding Sources NIH R01 92389022; NIH T32 AI170478; Mayo Clinic Graduate School of Biomedical Sciences Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description A durable T cell immunity against cancer is dependent on a continually refilling of effector CD8+ T cells. Thymic output has been correlated with favorable prognosis in cancer patients of advanced ages, suggesting thymus is an important source for refilling T cells that are capable of controlling cancer progression in the periphery. However, it remains unclear how PD-1 signals regulate the cytotoxic potential of CD8+ T cells in thymus before they egress to the periphery to establish durable anti-tumor immunity. Here we report PD-1 signaling prelimits thymic single positive (SP) CD8+ T cells to acquire cytotoxic potential by downregulating Gzmb and Nkg7, which are required for CD8+ T cell-mediated cytotoxicity. Unexpectedly, we found the absence of Pdcd1 also led to upregulation of Tox and Tim3 in thymic SP CD8+ T cells, thereby pre-programming these cells for exhaustion within the tumor. Thus, the absence of PD-1 signals in CD8+ T cells only partially delayed tumor growth in peripheral tissues. To improve therapeutic effects of PD-1 inhibition, we observed that tumor growth in CD8-specific Pdcd1 conditional knockout mice was further suppressed by treatment with a PD-L1 antibody that blocks PD-L1 and CD80 interaction. Our results imply that PD-1 inhibition promotes the expansion of effector cytotoxic CD8+ T cells but also retains T cell exhaustion potential, which can be mitigated by PD-L1 blockade that allows more CD80 to provide costimulatory signals to T cells via CD28. Funding Sources NCI R01CA256927 NCI R01CA261932 NCI P30CA15083 Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)