T-cell exhaustion pathways (Tex)

T-cell exhaustion is a state of T-cell dysfunction that occurs during chronic antigen exposure, typically in the context of cancer or chronic viral infections (Wherry & Kurachi, 2015, Nature Reviews Immunology). It is defined by the progressive loss of effector functions, such as the production of IL-2, TNF-alpha, and IFN-gamma, alongside the sustained expression of multiple inhibitory receptors like Programmed cell death protein 1 (PD-1) and Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) (McLane et al., 2019, Annual Review of Immunology). This state is governed by a unique transcriptional and epigenetic landscape, notably involving the transcription factor Thymocyte selection-associated high mobility group box protein (TOX) (Alfei et al., 2019, Nature). While exhaustion serves as a physiological mechanism to limit immunopathology during persistent infection, it also facilitates immune evasion by tumors (Blank et al., 2019, Nature Reviews Immunology). Therapeutic interventions, such as immune checkpoint inhibitors, target these pathways to reinvigorate exhausted T cells and restore anti-tumor or anti-viral immunity (Pardoll, 2012, Nature Reviews Cancer). However, the degree of reinvigoration is often limited by the epigenetic stability of the exhausted state, particularly in terminally exhausted subsets (Wherry & Kurachi, 2015). Understanding the heterogeneity of exhausted T cells, including progenitor and terminally exhausted populations, is critical for optimizing immunotherapy.

Other names

T-cell exhaustionT-cell dysfunctionT-cell hyporesponsivenessExhausted T-cell state

Blockade of inhibitory immune checkpoint receptors to disrupt negative signaling in T cells, thereby reversing the exhausted phenotype and restoring effector functions such as cytokine production and cytolytic activity (Pardoll, 2012, Nature Reviews Cancer).