REVIEW article
Front. Immunol.
Sec. Cancer Immunity and Immunotherapy
Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1658576
This article is part of the Research TopicT Regulatory Cells: Mechanisms and Therapeutical AdvancesView all 3 articles
Hybrid Regulatory T Cells (hTregs): Camouflaged Architects of Tumor Immunity
Provisionally accepted- 1Division of Medical Oncology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, United States
- 2Pelotonia Institute for Immuno-Oncology, The Ohio State University Comprehensive Cancer Center Arthur G James Cancer Hospital and Richard J Solove Research Institute, Columbus, United States
- 3Department of Surgery, School of Veterinary Medicine and Animal Sciences, University of Sao Paulo, Sao Paulo, Brazil
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Distinct from conventional Foxp3+ regulatory T cells (Tregs), T-bet+ Tregs represent a stable subset of immunosuppressive T cells characterized by co-expression of the transcription factors (TFs) Foxp3 and T-bet. Given that Tregs were also reported to co-express Foxp3 together with effector T cell TFs such as GATA3, or RORt, we propose the term hybrid Tregs (hTregs) to distinguish between these Tregs that co-express Foxp3 together with effector T cell TFs from conventional Foxp3+ Tregs. Therefore, this review will focus on hTreg cells, a specific subset of CD4⁺ T cells, and discuss the different types of hTregs with particular emphasis on T-bet⁺ hTregs. T-bet+ hTregs exhibit unique features including IFN-γ production, high expression of immune checkpoints (PD-1, CTLA-4, GITR, OX40, TIGIT), and chemokine receptors (CXCR3, CCR5). Through secretion of IL-10, TGF-β and IFN-γ, T-bet+ hTregs modulate both innate and adaptive immune responses within the tumor microenvironment (TME). Their high expression of CD73 contributes to adenosine-mediated immunosuppression, while CXCR3 and CCR5 facilitate their recruitment to inflammatory sites. T-bet+ hTregs were reported to accumulate in multiple human cancers, including lung, ovarian, and colorectal carcinomas. Despite these advancements, the function of hTregs in diseases such as cancer remains poorly understood, and requires further investigations. For instance, some studies suggest T-bet+ hTregs to be anti-inflammatory due to their production of IL-10, TGF-β, and superior suppressive capacity compared to conventional Tregs. Yet, other studies have reported that T-bet+ hTregs exhibit enhanced proinflammatory functions in colitis and other pathologies. We will then highlight current known mechanisms that promote the differentiation and functions of T-bet+ hTregs in cancer. Lastly, we will discuss the advancements and opportunities for therapeutic targeting of T-bet+ hTregs in cancer immunotherapy.
Keywords: regulatory T cells, Hybrid Tregs, T-bet+ hTregs, GATA3, Foxp3, Tumormicroenvironment, Immunotherapy
Received: 02 Jul 2025; Accepted: 03 Sep 2025.
Copyright: © 2025 Azimnasab-sorkhabi, Soltani-asl, Kfoury Junior and Ansa-Addo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ephraim Abrokwa Ansa-Addo, Division of Medical Oncology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, United States
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