{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T12:17:01Z","timestamp":1783513021298,"version":"3.55.0"},"reference-count":45,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"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":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Regulatory T cells play a pivotal role in shaping immune interactions, limiting antitumor immunity, and impairing the activity of engineered effector cells. Overcoming regulatory T (Treg) cell\u2013mediated immunosuppression is critical to unlock the full therapeutic potential of chimeric antigen receptor (CAR)-cell therapies. Here, we develop \u201carmored\u201d anti-CD19 CAR-NK cells coexpressing GITR ligand (GITRL) (CAR19-GITRL-NK) to both target malignant B cells and locally counteract Treg-mediated suppression. GITR is highly expressed on Tregs, and engagement by its ligand GITRL can modulate their function, providing a rational strategy to reprogram the tumor microenvironment.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      We generated anti-CD19 NK-92 and primary peripheral blood NK (PB-NK) cells with or without GITRL coexpression using lentiviral vectors, and evaluated their functionality and therapeutic potential. CAR19-GITRL-NK-92 cells were analyzed regarding their expansion, metabolism, cytotoxicity, cytokine secretion, degranulation, and\n                      <jats:italic>in vivo<\/jats:italic>\n                      antitumor potential. The cytotoxic activity of CAR19-GITRL PB-NK cells was examined, and their growth was measured in the presence of T CD4\u207a cells transduced with FoxP3 expression vector (iTreg-FoxP3) used as a model for Treg cells.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      CAR19-GITRL-NK-92 cells displayed superior expansion and enhanced metabolic fitness. Functionally, both CAR constructs increased the cytotoxicity of NK-92 and cytokine secretion against CD19\u207a Nalm-6 and Namalwa cells in vitro. RNA-Seq revealed 54 upregulated and 34 downregulated genes in CAR19-GITRL-NK-92 versus CAR19-NK-92 cells, with enrichment of pathways linked to immune activation, proliferation, chemotaxis, and cytotoxicity, including increased expression of NCR2, CD2, CMKLR1, IRF5, KIT, and PTPN3.\n                      <jats:italic>In vivo<\/jats:italic>\n                      , CAR19-GITRL-NK-92 cells achieved superior tumor control and the longest overall survival. In primary NK cells, CAR19-GITRL enhanced killing of CD19\u207a targets, and GITRL expression attenuated iTreg-FoxP3 mediated inhibition in CAR-NK cells, indicating a resistance mechanism to Treg suppression.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>Collectively, these data position CAR19-GITRL-NK cells as a potent and innovative strategy that couples direct tumor targeting with active undermining of Treg-driven immunosuppression for the treatment of B-cell leukemias and lymphomas.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1818610","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T05:48:09Z","timestamp":1783403289000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Coexpression of GITRL confers resistance to Treg cell-mediated immunosuppression to anti-CD19 CAR-NK cells"],"prefix":"10.3389","volume":"17","author":[{"given":"Dayane","family":"Schmidt","sequence":"first","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sima","family":"Ebrahimabadi","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariane Cariati","family":"Tirapelle","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Camilly Melo","family":"Garcia Ferreira","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matheus Henrique","family":"dos Santos","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alison Felipe","family":"Biggi","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mara Elisama","family":"da Silva Janu\u00e1rio","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rodrigo Tocantins","family":"Calado","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, Brazil"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Virginia","family":"Pican\u00e7o-Castro","sequence":"additional","affiliation":[{"name":"Center for Cell-based Therapy (CTC), Regional Blood Center of Ribeir\u00e3o Preto, University of S\u00e3o Paulo","place":["Ribeir\u00e3o Preto, S\u00e3o Paulo, 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