Thesis Julian Freen-van Heeren

Summary

CD8+ T cells are critical to protect us from pathogenic microbes and to keep malignantly transformed cells in check. To do so, they produce various effector molecules, including the prototypical T cell cytokine interferon (IFN)-g. Cytokine production is (partially) regulated through post-transcriptional events, where regulatory elements in mRNA molecules determine mRNA half-life, location and translational rate. Together, these events influence the protein production by T cells. Here, we show that one class of post-transcriptional regulatory elements, AU-rich elements (AREs), regulate IFN-g protein production in human and murine T cells. Deleting the AREs in the IFNG gene resulted in increased IFN-g production by human T cells, and rendered murine T cells refractory to inhibitory signals in a tumor model, which significantly improved anti-tumor responses.

Furthermore, we investigated the pathways engaged upon Toll-like receptor (TLR) costimulation. TLR ligands engage different (post)-transcriptional mechanisms to enhance the cytokine production of both human and murine T cells. To investigate the relation between cytokine mRNA and protein, we here described a novel method for the simultaneous measurement thereof.

Lastly, we generated a novel CRISPR/Cas9-tool to genetically modify human T cells. This method does not make use of viral vectors and is electroporation-free. Therefore, it is potentially suitable for augmenting the effector function of T cells used in cellular therapies.

Together, the work in this thesis provides new tools to study and genetically manipulate T cells, and potentially provides novel angles to enhance T cell effector function for therapeutic applications.