TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Proc Natl Acad Sci U S A. 2023 Nov 28;120(48):e2313228120. doi: 10.1073/pnas.2313228120. Epub 2023 Nov 21.

Abstract

Transforming growth factor β (TGF-β) directly acts on naive, effector, and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer; however, the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or proinflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β before or after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

Keywords: CD8 T cell; TGF beta; effector; memory T cell; trafficking.

MeSH terms

  • CD8-Positive T-Lymphocytes / metabolism
  • Memory T Cells*
  • Receptors, Antigen, T-Cell / metabolism
  • Signal Transduction
  • Transforming Growth Factor beta* / genetics

Substances

  • Transforming Growth Factor beta
  • Receptors, Antigen, T-Cell