Immunology
Abstract
Immune checkpoint blockade (ICB), including PD-1/PD-L1 inhibitors, has transformed cancer therapy but benefits only a subset of patients. Understanding how PD-L1 is regulated and identifying strategies to overcome resistance remain critical. Here, we identify SIRT2 as a key positive regulator of PD-L1 across multiple human cancers. Unexpectedly, SIRT2 does not act at the transcriptional level but stabilizes PD-L1 protein by preventing ubiquitin-mediated degradation. Mechanistically, SIRT2 maintains the protein stability of USP22, a PD-L1 deubiquitinase. Loss of SIRT2 reduces USP22 levels, whereas ectopic USP22 fully rescues PD-L1 expression and reverses the enhanced antitumor immunity induced by SIRT2 inhibition. We further show that SIRT2 directly deacetylates USP22 at lysines 382 and 505 within its catalytic domain, promoting USP22 deubiquitinase activity and protecting both itself and its substrates from degradation. Our findings reveal a molecular mechanism by which an acetylation–deacetylation switch dynamically regulates deubiquitinase catalytic activity. Therapeutically, SIRT2 inhibition synergizes with PD-1/PD-L1 blockade and USP22 inhibition to enhance antitumor immunity. Consistently, protein but not mRNA levels of SIRT2, USP22, and PD- L1 positively correlate in human bladder cancer and melanoma. Together, these findings define a SIRT2–USP22–PD-L1 axis driving tumor immune evasion and highlight SIRT2 as a promising target to improve ICB efficacy.
Authors
Na Li, Qiong Gao, Huijun Jia, Guoqing Xue, Yuanzhang Zhou, Shengnan Wang, Suxian Ma, Bingjin Hu, Zhuoyue Zhao, Chen Su, Yinghong Liu, Wenxuan Xi, Zhonghao Li, Donna D. Zhang, Peng Chu, Zhaolin Sun, Deyu Fang
Abstract
The cyclic dinucleotide 2′3′–cyclic guanosine monophosphate–adenosine monophosphate (2′3′-cGAMP) serves as a central immunotransmitter that propagates stimulator of interferon gene–dependent (STING-dependent) innate immunity across tissues; however, how microenvironmental metabolites regulate its spatiotemporal dynamics remains unknown. Here, we identified polyamines (spermine and spermidine) as critical rheostats controlling 2′3′-cGAMP functionality. Mechanistically, polyamines sequestered 2′3′-cGAMP into polymer-like aggregates, blocking intercellular propagation and suppressing intracellular STING activation by reducing ligand-receptor binding affinity. Deficiency of spermidine and spermine N1-acetyltransferase 1 (SAT1), the rate-limiting enzyme in polyamine catabolism, elevated polyamine levels to entrap extracellular 2′3′-cGAMP and inhibit STING activation. Synergistic administration of endogenous 2′3′-cGAMP with SAT1 stabilizer N1,N11-diethylnorspermine restored 2′3′-cGAMP bioavailability and STING signaling, facilitated type I interferon responses to reprogram immunologically suppressive tumors into immunologically active states and enhanced tumor clearance. Our study established polyamine–cGAMP interactions as a critical spatiotemporal regulatory mechanism for tissue-level immunity, providing a unified model for metabolite-mediated cyclic GMP-AMP synthase–STING (cGAS-STING) regulation across diseases.
Authors
Yunjin Ma, Chunyuan Zhao, Jiacheng Guo, Yue Fu, Wei Wang, Jiangong Zhang, Kun Zhao, Xiangbo Meng, Zhongshang Yuan, Chengjiang Gao, Mutian Jia, Ying Qin, Hui Song, Wei Zhao
Abstract
Immune checkpoint inhibitor-induced inflammatory arthritis (ICI-IA) significantly impairs cancer therapy and patient quality of life, yet its pathogenic mechanisms remain unclear. Through integrated single-cell multi-omics analysis of paired peripheral blood, synovial fluid, and tumor samples from longitudinal ICI-IA cohorts and matched controls, we identified a unique regulatory T-cell (Treg) population co-expressing CD137 and IL-6R (AtpTreg). These cells exhibited reduced immunosuppressive capacity while aberrantly producing high level of IL-17 and promoting proinflammatory responses of synoviocytes. AtpTreg exhibits shared clonotypes and phenotypes across tissue compartments. Notably, AtpTreg frequency correlates with increased arthritis severity yet paradoxically associates with improved overall survival. Anti-IL6R therapy reduced AtpTreg levels, corresponding with improved arthritis outcomes and quality of life, without compromising anti-tumor immunity. Our findings define a pathogenic Treg subset in ICI-IA and validate IL-6R blockade as a mechanism-based therapeutic strategy, bridging mechanistic discovery to clinical translation. This study is registered at ClinicalTrials.gov (NCT07357636).
Authors
Yifei Ma, Nianqi Liu, Yan Li, Denghan Zhang, Shaohui He, Jun Lv, Yongluo Jiang, Guangmin Jian, Jingyao Zhang, Pengfei Zhu, Yue Ma, Jiacai Lin, Jin Li, Tong Wu, Yiwei Xu, Xiajie Lyu, Youlong Wang, Yiming Li, Yu Si Niu, Zhenyun Guo, Churong Lin, Ningnan Fang, Wei Jiang, Lihong Wang, Mengqin Yuan, Shenyue Wang, Shulin Huang, Qi Huang, Jinjian Li, Jun Lu, Bocen Chen, Guanqing Zhong, Haizhou Liu, Fadian Ding, Shangeng Weng, Rui Li, Ao Zhang
Abstract
Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Current therapies are associated with substantial morbidity, and prognosis remains poor in high-risk subgroups, particularly those with TP53 mutations or relapsed disease. Cellular senescence is a tumor-suppressive program implicated in MB, but its role in anti-tumor immunity remains incompletely understood. We found that protein phosphatase 2A (PP2A) regulated immunogenic senescence in MB. Genetic ablation of the PP2A catalytic subunit, PP2Ac, or depletion of the regulatory subunit PP2A-B56α induced senescence in MB models. PP2Ac-deficient senescent cells exhibited increased MHC-I expression and enhanced immunogenicity. In syngeneic orthotopic models, PP2Ac loss prolonged survival in an immune- and CD8+ T cell-dependent manner. Analysis of patient datasets showed that senescence-associated gene signatures correlated with improved survival. Single-cell transcriptomic analysis further revealed that senescent MB cells were heterogeneous and that reduced PP2A activity was associated with an immunogenic senescence state. Because the PP2A inhibitor LB-100 has limited potency and off-target effects, we developed a lipid nanoparticle platform to deliver siRNA targeting PPP2CA. LNP-siPP2Ac efficiently silenced PP2Ac in vitro and, when delivered locally in vivo, prolonged survival in a CD8+ T cell-dependent manner. Together, these findings identify PP2A as a regulator of immunogenic senescence in MB and support PP2Ac targeting as a therapeutic strategy.
Authors
Winson S. Ho, Isha Mondal, Jingjing Liu, Raymond Sun, Jiawei Huo, Chao Gao, Oishika Das, Daren Tieu, Jingqi Sun, Hanchen Lin, Peng Zhang, Jiyang Yu, Rongze Olivia Lu
Abstract
Plasmodium falciparum (Pf) induces the clonal expansion of antigen-specific type 1 regulatory T (Tr1) cells capable of long-term memory. Tr1 cells comprise nearly 90% of the Pf blood stage antigen-specific CD4+ T cell pool in children. Though, whether Tr1 cells contribute to protection from malaria remains undetermined. To address this critical knowledge gap, we first performed scRNA-seq on gated cell populations and validated CXCR6+ CD127- as new phenotypic markers to enrich for bona-fide Tr1 cells. Importantly, these Tr1 cells potently suppressed the proliferation of other CD4+ T cells in vitro via IL-10 secretion. Among children living in malaria-endemic Uganda, CXCR6+ CD127- Tr1 cells were the dominant responding subset to Pf-infected red blood cell stimulation in vitro. They also rapidly expanded following malaria and expressed IL-10 and IFNγ during infection in vivo. Tr1 abundance correlated with plasma concentrations of granzyme A, IFNγ, IL-10, and LAG3, suggesting that these cells act systemically. Higher CXCR6+ CD127- Tr1 cell frequencies correlated with a lower probability of symptoms given parasitemia but were also associated with delayed parasite clearance among untreated, asymptomatic children. These data suggest that Tr1 cells help mediate clinical immunity to malaria but may also facilitate parasite persistence through mechanisms of immune regulation.
Authors
Jason Nideffer, Florian Bach, Steven Strubbe, Luis Lopez, Maato Zedi, Felistas Nankya, Jessica Briggs, Kattria van der Ploeg, Kenneth Musinguzi, Soyeon Kim, Aracely Garcia Romero, Arefin Keya, Kylie Camanag, Savannah Lewis, Muhammad Abdelbasset, Bing Wang, Allison Boss, Evelyn Nansubuga, Joaniter I. Nankabirwa, Emmanuel Arinaitwe, Saki Takahashi, Grant Dorsey, Bryan Greenhouse, Isabel Rodriguez-Barraquer, Moses R. Kamya, Rosa Bacchetta, Isaac Ssewanyana, Ashraful Haque, Maria Grazia Roncarolo, Prasanna Jagannathan
Abstract
BACKGROUND. Approaches to achieving antiretroviral therapy (ART)-free remission from HIV-1 must consider that people over 50 years now comprise the majority of people with HIV (PWH) on ART in various regions, including the U.S. METHODS. We report a double-blind, randomized trial in which PWH on ART, aged 21-60 years, received modified vaccinia Ankara (MVA)-vectored vaccines, MVA.tHIVconsv3 (M3) and MVA.tHIVconsv4 (M4), either alone or in combination (n=7/group) or saline placebo (n=3). M3 and M4 contain complementary HIVconsvX immunogens that each span the same regions in HIV-1 Gag and Pol but differ at approximately 8% at the amino acid level. RESULTS. M3, M4, and M3M4 regimens were well tolerated and all significantly increased both the frequency (peak median increase ~3-fold) and breadth of the HIVconsvX-specific T-cell response while redirecting T cells to target conserved regions in HIV-1 for up to 10 weeks post-vaccination. We also demonstrated that vaccination increased frequencies of T-cells targeting participant autologous HIV-1 sequences. Vaccination mostly expanded pre-existing HIV-1-specific T cells, did not impact CD4 T-cell activation, low-level viremia, or integrated HIV-1 provirus. Linear regression indicated that age was independently and negatively associated with the change in T-cell frequency at 1-, 2- and 10-weeks after vaccination (~1.41-fold decrease per 10 years older). After adjusting for age, years on ART was positively associated with HIVconsvX-specific T-cell frequencies at 1- and 2-weeks following vaccination. CONCLUSION. In PWH receiving ART, MVA.HIVconsvX vaccines significantly increased T cells targeting conserved regions of HIV-1. Novel strategies may be required to enhance anti-HIV-1 immunity in older adults. TRIAL REGISTRATION. NCT03844386.
Authors
Cynthia L. Gay, Yinyan Xu, Ann Marie K. Weideman, Fiona R. Shaw, JoAnn D. Kuruc, Shayla Z. Conrad, Sofia A. Mariano, Shahryar Samir, Sallay Kallon, Alexis T. Sponaugle, Joanna A. Warren, Genevieve T. Clutton, Maria Abad-Fernandez, Carolina Kapper, Alex B. Bradley, Caroline E. Baker, Susan M. Pedersen, Matthew Moeser, Lauren Burke, Edmund G.T. Wee, Alison Crook, Gregory M. Laird, Joshua C. Cyktor, John W. Mellors, Shuntai Zhou, Lawrence Fox, Joe J. Eron, David M. Margolis, Michael G. Hudgens, Tomáš Hanke, Nilu Goonetilleke
Abstract
BACKGROUND. Primary therapy for high-risk bladder cancer (BCa) is repeated instillations of the tuberculosis vaccine Bacillus Calmette-Guerin (BCG). Although BCG reduces the risk of recurrence by more than half, the mechanisms underlying its immune-activating effects remain unknown. Our objective was to investigate how the immune response differs between BCG responders and non-responders and to compare systemic and local immune responses. METHODS. We performed single-cell RNA sequencing (scRNA-seq) of isolated immune cells adjacent to high-risk bladders in BCG responders and non-responders before and after BCG. We also compared concurrent scRNA-seq profiles of circulating immune cell populations with those of bladder immune cells. RESULTS. We identify an increase in Th17-like Th1 cells in BCG responders, characterized by greater expression of pro-inflammatory cytokines. Alternatively, non-responders show increased CD8+ T-cell exhaustion and T regulatory cells. We identify that the primary mechanism driving divergent T-cell activity is altered polarization and immunosuppressive signaling with myeloid cells. Using a machine-learning-based approach, we identify that Th17-like Th1 cytokines, such as IL-17, IL-21, and IL-26, are predictive of response, which is subsequently validated in a separate BCG-treated BCa cohort. CONCLUSION. Together, these findings suggest that dynamic regulation of myeloid-T cell interactions can be critical for outcomes of BCG treated bladder cancer.
Authors
Ryan J. Brown, Mairah T. Khan, Andrew J. Houston, Hongshen Niu, Joseph R. Podojil, Bonnie Choy, Weiguo Cui, Joshua James Meeks
Abstract
Conventional type-1 dendritic cells (cDC1) are the main mediators of crosspresentation of tumor antigens to CD8+ T cells and provide a context of costimulatory molecules and cytokines that lead to cytotoxic T lymphocyte (CTL) responses. We analyzed bulk RNA sequences from 7 key clinical trials testing checkpoint inhibitors across multiple cancer types. cDC1- and CD8-associated gene signatures were analyzed. Multiplex tissue immunofluorescence was used to quantify cDC1 in melanoma, urothelial cancer, and non-small-cell lung cancer (NSCLC) samples and assess cDC1 tissue neighborhoods. Melanoma samples were studied with Xenium spatial transcriptomics (ST) and one series of NSCLC was analyzed using GeoMX-DSP. Strong associations across tumor types were found between cDC1 and CD8+ T cell transcripts with clinical outcomes. As mechanistically expected, transcripts for the CCL4 and CCL5 chemokines and the growth factor FLT3-L showed associations with cDC1 abundance. Tissue immunofluorescence showed a strong correlation of cDC1 and CD8+ T cell infiltration with clinical benefit upon treatment with checkpoint inhibitors (CPIs). Moreover, short distance between cDC1 and CD8+ T cells was found to define tissue niches associated with favorable outcomes. ST revealed recent T cell activation within immune cDC1-rich niches. cDC1 abundance, which determines CD8+ T lymphocyte density and activation in tumor tissues across cancer types, is strongly associated with clinical response to CPI-based immunotherapies.
Authors
Alvaro Lopez-Janeiro, José González-Gomariz, Fadi Issa, Joanna Hester, Angelo Porciuncula, Alvaro Teijeira, Carlos Luri-Rey, David Ruiz-Guillamon, Jose Luis Perez-Gracia, Elisabeth Perez-Ruiz, Isabel Barragan, Salvador Martín-Algarra, Miguel F. Sanmamed, Ignacio Ortego, Maria E. Rodriguez-Ruiz, Raluca Alexandru, Inmaculada Rodriguez, Saioa Arrieta-Aranzueque, David Rimm, Thazin Aung, Kurt A. Schalper, Carlos E. de Andrea, Ignacio Melero
Abstract
Neuropathic pain affects over 20 million people in the United States, and painful diabetic neuropathy (PDN), a common complication of diabetes, is among its most prevalent and treatment-resistant forms. Although PDN is characterized by nociceptor dysfunction, the upstream peripheral mechanisms remain incompletely understood. While dorsal root ganglion (DRG) nociceptor hyperexcitability is a hallmark of PDN, emerging evidence suggests that non-neuronal skin cells may modulate nociceptor function. Here, we investigated whether epidermal Langerhans cells (LCs) contribute to neuropathic pain in PDN through neuroimmune signaling. Using a clinically relevant high-fat diet (HFD) mouse model, transgenic LC ablation, behavioral assays, human skin biopsies, and single-cell RNA sequencing of epidermis and DRG, we found that LC density increased in male diabetic mice in parallel with mechanical allodynia. In human PDN skin, LCs exhibited increased volume and dendritic complexity correlating with diabetes duration. Genetic depletion of LCs prevented mechanical allodynia and spontaneous pain-like behavior in male, but not female, HFD mice, revealing a sex-dependent contribution. Single-cell and interactome analyses identified male-specific inflammatory LC programs, including upregulation of chemokine signaling pathways. Consistently, LC secretome profiling showed increased CCL2 release, and local CCR2 blockade reversed allodynia. These findings identify epidermal LCs as peripheral regulators of PDN pain and highlight sex-dependent chemokine-mediated neuron-immune communication at the skin-nerve interface.
Authors
Paola Pacifico, Dale George, Nirupa D. Jayaraj, Dongjun Ren, James S. Coy-Dibley, Abdelhak A. Belmadani, Sofia Veronesi, Mirna Andelic, Daniele Cartelli, Grazia Devigili, Raffaella Lombardi, Giuseppe Lauria Pinter, Amy S. Paller, Richard J. Miller, Daniela M. Menichella
Abstract
Regulatory T (Treg) cells expressing Forkhead Box P3 (FOXP3) play crucial roles in maintaining immune tolerance and tissue integrity. EZH2, a Histone H3 lysine 27 (H3K27) methyltransferase, is known as a key regulator of Treg cell identity and suppressive function upon activation. Here, we demonstrate that the H3K27 lysine demethylase KDM6B, which catalyzes the opposing reaction to EZH2, was also required for Treg cell identity and function after activation. Treg-specific deletion of Kdm6b impaired tissue Treg cell fate and function. KDM6B was upregulated following T cell antigen receptor (TCR) signaling in Treg cells and contributed to the regulation of Treg-associated gene expression through both direct and indirect mechanisms. A subset of Treg functional genes were direct targets of KDM6B and were co-occupied by FOXP3 at cis-regulatory regions, where KDM6B recruitment limited H3K27me3 accumulation. More broadly, KDM6B-dependent H3K27 demethylation facilitated Treg gene expression programs that supported tissue Treg homeostasis.
Authors
Minghong He, Beisi Xu, Pria G. Bose, Morgan J. McCullough, Rani S. Sellers, Xinying Zong, Wenjie Qi, Brianna L. Banten, Miriya K. Tune, Matthew P. Zimmerman, Genevieve N. Mullins, Brian C. Miller, J. Justin Milner, Jason K. Whitmire, Ageliki Tsagaratou, Karl B. Shpargel, Claire M. Doerschuk, Yong-Dong Wang, Jacob A. Steele, Shondra M. Pruett-Miller, Yongqiang Feng, Jason R. Mock
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)