{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T06:04:52Z","timestamp":1781071492476,"version":"3.54.1"},"reference-count":53,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T00:00:00Z","timestamp":1781049600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"\n Background<\/jats:title>\n \n Non-small cell lung cancer (NSCLC) has a high incidence rate, and most patients develop resistance to anti-PD-1 immunotherapy, resulting in shortened survival. Current evidence suggests that peripheral T cells, particularly CD8\n +<\/jats:sup>\n T cells, play a key role in the response to anti-PD-1 immunotherapy. However, the key molecules that impair peripheral CD8\n +<\/jats:sup>\n T cell function and thereby drive resistance to anti-PD-1 immunotherapy remain unclear. This study aims to demonstrate that loss of cathepsin L (CTSL) expression in peripheral CD8\n +<\/jats:sup>\n T cells is a critical factor driving resistance to anti-PD-1 therapy in NSCLC.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n Using flow cytometry, we tracked the dynamic expression patterns of CTSL in peripheral CD8\n +<\/jats:sup>\n T cells from NSCLC patients receiving anti-PD-1 therapy, as well as its longitudinal distribution across different T cell subsets. We then investigated the association between CTSL expression levels in peripheral CD8\n +<\/jats:sup>\n T cells and the expression of anti-tumor effector molecules. Finally, through bioinformatics analysis, flow cytometry, ELISA, and pharmacological interventions, we explored the functional relationship between CTSL and NLRP3 inflammasome activation in mediating the anti-tumor function of CD8\n +<\/jats:sup>\n T cells.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n CTSL expression in peripheral CD8\n +<\/jats:sup>\n T cells was demonstrated as a predictor of improved clinical response to anti-PD-1 immunotherapy in NSCLC (\n p &lt; 0.01<\/jats:italic>\n ). Subset analysis revealed that in anti-PD-1-resistant patients, CTSL expression was significantly reduced in effector memory CD8\n +<\/jats:sup>\n T cells and terminally differentiated effector memory CD8\n +<\/jats:sup>\n T cells. Mechanistically, CTSL upregulation enhanced the expression of functional molecules in CD8\n +<\/jats:sup>\n T cells, including perforin, granzyme, IFN-\u03b3, and Ki67. Functional exploration experiments further showed not only a positive correlation between CTSL and NLRP3 expression in peripheral CD8\n +<\/jats:sup>\n T cells, but also that activation of NLRP3 reversed the anti-tumor dysfunction of CD8\n +<\/jats:sup>\n T cells induced by CTSL inhibition.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n \n Loss of CTSL expression in peripheral CD8\n +<\/jats:sup>\n T cells is a key factor driving resistance to anti-PD-1 immunotherapy in NSCLC. CTSL loss may impair the anti-tumor function of CD8\n +<\/jats:sup>\n T cells by inhibiting NLRP3 inflammasome activation. This study not only provides a potential circulating biomarker for predicting response to anti-PD-1 therapy, but also offers new perspectives for understanding the mechanisms of resistance.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1863563","type":"journal-article","created":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T05:37:05Z","timestamp":1781069825000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["CTSL loss leads to anti-PD-1 immunotherapy resistance in lung cancer by suppressing the anti-tumor function of peripheral CD8+ T cells"],"prefix":"10.3389","volume":"17","author":[{"given":"Ying","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine, Infectious Diseases and Pathogen Biology Center, The First Hospital of Jilin University","place":["Changchun, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, Infectious Diseases and Pathogen Biology Center, The First Hospital of Jilin University","place":["Changchun, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xueyang","family":"Zou","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, Infectious Diseases and Pathogen Biology Center, The First Hospital of Jilin University","place":["Changchun, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiancheng","family":"Xu","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, Infectious Diseases and Pathogen Biology Center, The First Hospital of Jilin University","place":["Changchun, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,10]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"53","DOI":"10.1007\/s00408-025-00801-x","article-title":"Update 2025: Management of non-small-cell lung cancer","volume":"203","author":"Jeon","year":"2025","journal-title":"Lung"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1200\/JCO.21.01497","article-title":"First-line immunotherapy for non-small-cell lung cancer","volume":"40","author":"Reck","year":"2022","journal-title":"J Clin Oncol"},{"key":"B3","doi-asserted-by":"publisher","first-page":"209","DOI":"10.1016\/j.ccell.2023.12.013","article-title":"Clinical and molecular features of acquired resistance to immunotherapy in non-small cell lung cancer","volume":"42","author":"Memon","year":"2024","journal-title":"Cancer Cell"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.3390\/ijms24031897","article-title":"A new plasmacytoid dendritic cell-based vaccine in combination with anti-PD-1 expands the tumor-specific CD8+ T cells of lung cancer patients","volume":"24","author":"Hannani","year":"2023","journal-title":"Int J Mol Sci"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1158\/0008-5472.CAN-18-0734","article-title":"Activation of NKT cells in an anti-PD-1-resistant tumor model enhances antitumor immunity by reinvigorating exhausted CD8 T cells","volume":"78","author":"Bae","year":"2018","journal-title":"Cancer Res"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.1126\/science.abd1329","article-title":"Recruiting T cells in cancer immunotherapy","volume":"372","author":"Yost","year":"2021","journal-title":"Science"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1016\/j.imbio.2023.152391","article-title":"Peripheral changes in T cells predict efficacy of anti-PD-1 immunotherapy in non-small cell lung cancer","volume":"228","author":"Lao","year":"2023","journal-title":"Immunobiology"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.2147\/CMAR.S580857","article-title":"Circulating tumor cell PD-L1 and peripheral blood CD8(+) T-cell PD-1 as dual liquid biopsy biomarkers for immunotherapy outcomes in advanced non-small cell lung cancer: A retrospective study","volume":"18","author":"Guan","year":"2026","journal-title":"Cancer Manag Res"},{"key":"B9","doi-asserted-by":"publisher","first-page":"134","DOI":"10.1186\/s13046-024-03046-3","article-title":"CXCR6-positive circulating mucosal-associated invariant T cells can identify patients with non-small cell lung cancer responding to anti-PD-1 immunotherapy","volume":"43","author":"Qu","year":"2024","journal-title":"J Exp Clin Cancer Res"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1705327114","article-title":"Proliferation of PD-1+ CD8 T cells in peripheral blood after PD-1-targeted therapy in lung cancer patients","volume":"114","author":"Kamphorst","year":"2017","journal-title":"Proc Nat Acad Sci U.S.A"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1158\/1078-0432.CCR-18-1449","article-title":"The first-week proliferative response of peripheral blood PD-1(+)CD8(+) T cells predicts the response to anti-PD-1 therapy in solid tumors","volume":"25","author":"Kim","year":"2019","journal-title":"Clin Cancer Res"},{"key":"B12","doi-asserted-by":"publisher","first-page":"61","DOI":"10.1016\/j.ejca.2016.12.011","article-title":"Peripheral CD8 effector-memory type 1 T-cells correlate with outcome in ipilimumab-treated stage IV melanoma patients","volume":"73","author":"Wistuba-Hamprecht","year":"2017","journal-title":"Eur J Cancer"},{"key":"B13","doi-asserted-by":"publisher","first-page":"309","DOI":"10.1007\/s00262-025-04086-0","article-title":"High baseline PD-1+ CD8 T cells and TIGIT+ CD8 T cells in circulation associated with response to PD-1 blockade in patients with non-small cell lung cancer","volume":"74","author":"Dutta","year":"2025","journal-title":"Cancer Immunol Immunother"},{"key":"B14","doi-asserted-by":"publisher","DOI":"10.3390\/cells9071679","article-title":"The ins and outs of cathepsins: Physiological function and role in disease management","volume":"9","author":"Yadati","year":"2020","journal-title":"Cells"},{"key":"B15","doi-asserted-by":"publisher","DOI":"10.1016\/j.bioelechem.2024.108856","article-title":"Novel selective and sensitive electrochemical sensor for detection of ovarian cancer biomarker, cathepsin L","volume":"162","author":"Paliwal","year":"2025","journal-title":"Bioelectrochemistry"},{"key":"B16","doi-asserted-by":"publisher","DOI":"10.18632\/aging.104147","article-title":"Genomic, epigenomic, and immune subtype analysis of CTSL\/B and SARS-CoV-2 receptor ACE2 in pan-cancer","volume":"12","author":"Li","year":"2020","journal-title":"Aging"},{"key":"B17","doi-asserted-by":"publisher","DOI":"10.1002\/ijc.29992","article-title":"Cathepsin L inactivation leads to multimodal inhibition of prostate cancer cell dissemination in a preclinical bone metastasis model","volume":"138","author":"Sudhan","year":"2016","journal-title":"Int J Cancer"},{"key":"B18","doi-asserted-by":"publisher","DOI":"10.1007\/s12094-015-1424-6","article-title":"Overexpression of cathepsin L is associated with gefitinib resistance in non-small cell lung cancer","volume":"18","author":"Cui","year":"2016","journal-title":"Clin Transl Oncol"},{"key":"B19","doi-asserted-by":"publisher","DOI":"10.1038\/s41590-025-02182-y","article-title":"Cathepsin L-dependent positive selection shapes clonal composition and functional fitness of CD4(+) T cells","volume":"26","author":"Petrozziello","year":"2025","journal-title":"Nat Immunol"},{"key":"B20","doi-asserted-by":"publisher","first-page":"10706","DOI":"10.1038\/s41467-025-64500-0","article-title":"Cathepsin L as a dual-target to mitigate muscle wasting while enhancing anti-tumor efficacy of anti-PD-L1","volume":"16","author":"Park","year":"2025","journal-title":"Nat Commun"},{"key":"B21","doi-asserted-by":"publisher","DOI":"10.1016\/j.brainres.2009.12.038","article-title":"Lipotoxicity-mediated cell dysfunction and death involve lysosomal membrane permeabilization and cathepsin L activity","volume":"1318","author":"Almaguel","year":"2010","journal-title":"Brain Res"},{"key":"B22","doi-asserted-by":"publisher","DOI":"10.1126\/science.280.5362.450","article-title":"Cathepsin L: Critical role in Ii degradation and CD4 T cell selection in the thymus","volume":"280","author":"Nakagawa","year":"1998","journal-title":"Science"},{"key":"B23","doi-asserted-by":"publisher","DOI":"10.1007\/s002510100320","article-title":"The CD4 T cell-deficient mouse mutation nackt (nkt) involves a deletion in the cathepsin L (CtsI) gene","volume":"53","author":"Benavides","year":"2001","journal-title":"Immunogenetics"},{"key":"B24","article-title":"Increase of regulatory T cells in the lymph node of cathepsin L mutant mice","volume":"71","author":"Camicia","year":"2011","journal-title":"Medicina"},{"key":"B25","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2018.02449","article-title":"Asparaginyl endopeptidase (legumain) supports human Th1 induction via cathepsin L-mediated intracellular C3 activation","volume":"9","author":"Freeley","year":"2018","journal-title":"Front Immunol"},{"key":"B26","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2567.2010.03299.x","article-title":"Human and mouse perforin are processed in part through cleavage by the lysosomal cysteine proteinase cathepsin L","volume":"131","author":"Konjar","year":"2010","journal-title":"Immunology"},{"key":"B27","doi-asserted-by":"publisher","DOI":"10.1158\/1078-0432.CCR-18-3041","article-title":"A variant of a killer cell immunoglobulin-like receptor is associated with resistance to PD-1 blockade in lung cancer","volume":"25","author":"Trefny","year":"2019","journal-title":"Clin Cancer Res"},{"key":"B28","doi-asserted-by":"publisher","first-page":"1523","DOI":"10.1038\/s41467-019-09234-6","article-title":"Metascape provides a biologist-oriented resource for the analysis of systems-level datasets","volume":"10","author":"Zhou","year":"2019","journal-title":"Nat Commun"},{"key":"B29","doi-asserted-by":"publisher","DOI":"10.1126\/sciimmunol.add4947","article-title":"Anti-PD-1 antibodies recognizing the membrane-proximal region are PD-1 agonists that can down-regulate inflammatory diseases","volume":"8","author":"Suzuki","year":"2023","journal-title":"Sci Immunol"},{"key":"B30","doi-asserted-by":"publisher","DOI":"10.1002\/cyto.a.24799","article-title":"OMIP-099: 31-color spectral flow cytometry panel to investigate the steady-state phenotype of human T cells","volume":"105","author":"Zacharias","year":"2024","journal-title":"Cytometry A"},{"key":"B31","doi-asserted-by":"publisher","DOI":"10.1007\/s00262-018-2160-x","article-title":"The binding of an anti-PD-1 antibody to Fc\u03b3RI has a profound impact on its biological functions","volume":"67","author":"Zhang","year":"2018","journal-title":"Cancer Immunol Immunother"},{"key":"B32","doi-asserted-by":"publisher","DOI":"10.1016\/j.jaut.2024.103339","article-title":"PD-1 antibody interactions with Fc gamma receptors enable PD-1 agonism to inhibit T cell activation - therapeutic implications for autoimmunity","volume":"149","author":"Feng","year":"2024","journal-title":"J Autoimmun"},{"key":"B33","doi-asserted-by":"publisher","DOI":"10.1016\/j.smim.2023.101800","article-title":"T cell fate decisions during memory cell generation with aging","volume":"69","author":"Sturmlechner","year":"2023","journal-title":"Semin Immunol"},{"key":"B34","doi-asserted-by":"publisher","DOI":"10.1039\/d0mt00057d","article-title":"Arsenic induces mTOR-dependent autophagy, whereas it impairs the autophagy-lysosome pathway and the potential role of TFEB in cultured dendritic cells","volume":"12","author":"Zhao","year":"2020","journal-title":"Metallomics"},{"key":"B35","doi-asserted-by":"publisher","DOI":"10.1034\/j.1600-0854.2000.010508.x","article-title":"Secretory lysosome biogenesis in cytotoxic T lymphocytes from normal and Chediak Higashi syndrome patients","volume":"1","author":"Stinchcombe","year":"2000","journal-title":"Traffic"},{"key":"B36","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.0901363","article-title":"Cutting edge: NF-kappaB activating pattern recognition and cytokine receptors license NLRP3 inflammasome activation by regulating NLRP3 expression","volume":"183","author":"Bauernfeind","year":"2009","journal-title":"J Immunol"},{"key":"B37","doi-asserted-by":"publisher","DOI":"10.1016\/j.febslet.2012.02.045","article-title":"TLR-induced NF-\u03baB activation regulates NLRP3 expression in murine macrophages","volume":"586","author":"Qiao","year":"2012","journal-title":"FEBS Lett"},{"key":"B38","doi-asserted-by":"publisher","DOI":"10.1016\/j.bbrc.2015.02.029","article-title":"NLRP3 inflammasome expression is driven by NF-\u03baB in cultured hepatocytes","volume":"458","author":"Boaru","year":"2015","journal-title":"Biochem Biophys Res Commun"},{"key":"B39","doi-asserted-by":"publisher","DOI":"10.1038\/aps.2014.148","article-title":"Inhibition of cathepsin L sensitizes human glioma cells to ionizing radiation in vitro through NF-\u03baB signaling pathway","volume":"36","author":"Yang","year":"2015","journal-title":"Acta Pharmacol Sin"},{"key":"B40","doi-asserted-by":"publisher","DOI":"10.1038\/ni.1669","article-title":"Proteolytic cleavage in an endolysosomal compartment is required for activation of Toll-like receptor 9","volume":"9","author":"Park","year":"2008","journal-title":"Nat Immunol"},{"key":"B41","doi-asserted-by":"publisher","first-page":"26","DOI":"10.1186\/s13098-021-00780-y","article-title":"TLR9 regulates NLRP3 inflammasome activation via the NF-kB signaling pathway in diabetic nephropathy","volume":"14","author":"Shen","year":"2022","journal-title":"Diabetol Metab Syndr"},{"key":"B42","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1016\/j.abb.2019.02.015","article-title":"The role of lysosomal cysteine cathepsins in NLRP3 inflammasome activation","volume":"670","author":"Campden","year":"2019","journal-title":"Arch Biochem Biophys"},{"key":"B43","doi-asserted-by":"publisher","DOI":"10.1096\/fj.202403101R","article-title":"Cathepsin L aggravates neuroinflammation via promoting microglia M1 polarization and NLRP3 activation after spinal cord injury","volume":"39","author":"Zhang","year":"2025","journal-title":"FASEB J"},{"key":"B44","doi-asserted-by":"publisher","DOI":"10.1016\/j.tibs.2016.09.002","article-title":"Mechanism and regulation of NLRP3 inflammasome activation","volume":"41","author":"He","year":"2016","journal-title":"Trends Biochem Sci"},{"key":"B45","doi-asserted-by":"publisher","DOI":"10.1371\/journal.ppat.1006196","article-title":"CD8+ T cell cytotoxicity mediates pathology in the skin by inflammasome activation and IL-1\u03b2 production","volume":"13","author":"Novais","year":"2017","journal-title":"PloS Pathog"},{"key":"B46","doi-asserted-by":"publisher","DOI":"10.1016\/j.it.2021.05.001","article-title":"NLRP3 inflammasomes that induce antitumor immunity","volume":"42","author":"Zhivaki","year":"2021","journal-title":"Trends Immunol"},{"key":"B47","doi-asserted-by":"publisher","DOI":"10.1084\/jem.20181218","article-title":"Host conditioning with IL-1\u03b2 improves the antitumor function of adoptively transferred T cells","volume":"216","author":"Lee","year":"2019","journal-title":"J Exp Med"},{"key":"B48","doi-asserted-by":"publisher","first-page":"1139","DOI":"10.1186\/s12967-024-05951-9","article-title":"Novel approach to alleviate lupus nephritis: Targeting the NLRP3 inflammasome in CD8(+)CD69(+)CD103(+) T(RM) cells","volume":"22","author":"Lai","year":"2024","journal-title":"J Transl Med"},{"key":"B49","doi-asserted-by":"publisher","DOI":"10.1016\/j.isci.2021.102548","article-title":"NLRC4 inhibits NLRP3 inflammasome and abrogates effective antifungal CD8(+) T cell responses","volume":"24","author":"Souza","year":"2021","journal-title":"iScience"},{"key":"B50","doi-asserted-by":"publisher","first-page":"35","DOI":"10.1615\/CritRevEukaryotGeneExpr.2024053577","article-title":"Foxm1-mediated transcriptional inactivation of NLRP3 inflammasome promotes immunosuppression in cervical cancer","volume":"34","author":"Ji","year":"2024","journal-title":"Crit Rev Eukaryot Gene Expr"},{"key":"B51","doi-asserted-by":"publisher","DOI":"10.1136\/jitc-2024-010013","article-title":"Phase I study of BMS-986299, an NLRP3 agonist, as monotherapy and in combination with nivolumab and ipilimumab in patients with advanced solid tumors","volume":"13","author":"Nelson","year":"2025","journal-title":"J Immunother Cancer"},{"key":"B52","doi-asserted-by":"publisher","DOI":"10.1158\/1535-7163.MCT-24-0501","article-title":"Denfivontinib activates effector T cells through the NLRP3 inflammasome, yielding potent anticancer effects by combination with pembrolizumab","volume":"24","author":"Kim","year":"2025","journal-title":"Mol Cancer Ther"},{"key":"B53","doi-asserted-by":"publisher","first-page":"4186","DOI":"10.1038\/s41467-018-06706-z","article-title":"Complement receptor CD46 co-stimulates optimal human CD8(+) T cell effector function via fatty acid metabolism","volume":"9","author":"Arbore","year":"2018","journal-title":"Nat Commun"}],"container-title":["Frontiers in Immunology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2026.1863563\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T05:37:07Z","timestamp":1781069827000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2026.1863563\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,10]]},"references-count":53,"alternative-id":["10.3389\/fimmu.2026.1863563"],"URL":"https:\/\/doi.org\/10.3389\/fimmu.2026.1863563","relation":{},"ISSN":["1664-3224"],"issn-type":[{"value":"1664-3224","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,10]]},"article-number":"1863563"}}