UC San Diego

T cell exhaustion impedes adoptive transfer cell therapy efficacy. Previous findings in the atypical IkB transcriptional modulator, IkBd, indicated that its overexpression (OE) enhances CD8+ T cell anti-tumor responses. In this study, we demonstrated that IkBd OE tumor infiltrating lymphocytes (TILs) increases proliferation in MC38 colorectal carcinoma tumor microenvironment using immunofluorescence. With intention to elucidate the signaling dynamics of TILs, we first confirmed the essential role of Cxcr6 in guiding effector CD8 population to a niche for increased survival. However, this gene appears dispensable for the enhanced effector function of IkBd OE T cells. Although we have proposed a potential method to improve adoptive therapy efficiency, it is still unknown what are the early transcriptional changes that directs CD8+ T cells to differentiate into distinct exhausted lineages. We developed the in vitro co-culture conditions that induces stable TIM3+/- bifurcation phenotype in CD8+ T cells, which is a representative of in vivo TILs. Subsequent cell trace and cytokine staining revealed independent pathways that lead to exhaustion, apoptosis and cytokine production. The co-culture assays established a robust model for further mRNA analysis to define the transcriptional change at initiation of the exhaustion program.