Regulatory T cell survival pathways (Treg survival pathways)

Regulatory T (Treg) cell survival pathways are the integrated signaling networks and transcriptional programs essential for the maintenance, fitness, and homeostatic proliferation of Foxp3-expressing regulatory T cells (Sakaguchi et al., 2020, Nature Reviews Immunology). The primary axis for Treg survival is the Interleukin-2 (IL-2) signaling pathway, where IL-2 binds to the high-affinity trimeric receptor (CD25/CD122/CD132) to trigger STAT5 phosphorylation, which directly maintains the expression of the master transcription factor Foxp3 (Fontenot et al., 2003, Nature Immunology; Abbas et al., 2018, Science Immunology). Beyond IL-2, Treg survival is supported by T-cell receptor (TCR) signaling and costimulatory molecules such as CD28, GITR, and OX40, which provide necessary survival signals and metabolic cues (Sakaguchi et al., 2020, Nature Reviews Immunology; Togashi et al., 2019, Nature Reviews Clinical Oncology). In oncology, these pathways are often hyper-activated, allowing Tregs to suppress anti-tumor immunity; thus, therapeutic strategies like anti-CTLA-4 or anti-CD25 antibodies aim to disrupt these survival signals to deplete intratumoral Tregs (Togashi et al., 2019, Nature Reviews Clinical Oncology). Conversely, in autoimmune diseases and transplantation, low-dose IL-2 or IL-2 mimetics are used to selectively bolster Treg survival pathways to restore self-tolerance and prevent tissue damage (Abbas et al., 2018, Science Immunology). However, modulating these pathways carries significant risks, including the potential for systemic immunosuppression or the induction of severe autoimmunity depending on whether the pathway is being agonized or antagonized (Togashi et al., 2019, Nature Reviews Clinical Oncology; Abbas et al., 2018, Science Immunology). Metabolic pathways, particularly fatty acid oxidation and the mTOR signaling axis, also play a critical role in sustaining Treg longevity in nutrient-poor environments like the tumor microenvironment (Sakaguchi et al., 2020, Nature Reviews Immunology). Understanding these survival mechanisms is crucial for developing precision immunotherapies that can selectively target or enhance Treg populations without affecting effector T cell function (Togashi et al., 2019, Nature Reviews Clinical Oncology).

Other names

Treg maintenance pathwaysFoxp3+ T cell survival signalingRegulatory T cell homeostasisTreg fitness pathways

Modulation of Treg survival and homeostasis through the activation or inhibition of cytokine signaling (e.g., IL-2/STAT5), costimulatory/coinhibitory receptors (e.g., CTLA-4, GITR), or metabolic regulators (e.g., mTOR).