Modulation of T Cell Antitumor Immunity Through Acetylcholine Signaling




Guagliano, Ryan

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Immunotherapies such as chimeric antigen receptor T cells (CAR-T cells) have shown promising results in many cancer patients but are still limited in solid cancers. Solid cancers contain immunosuppressive factors in the tumor microenvironment (TME), such as hypoxia and glucose deprivation. Antigen heterogeneity reduces therapy effectiveness in many cancers as CAR-T receptors need to recognize specific antigen that may be absent. This thesis investigates the function of a prominent TME metabolite: the neurotransmitter acetylcholine (ACh). Primary data from our lab shows that T cells infiltrating the TME have elevated ACh. Recent publications show ACh signaling influences mouse T cells to express a transcription factor FoxP3, a marker for regulatory T cells (Tregs) that contribute to the suppressive TME. However, there is little progress in testing the impact of these ACh-stimulated T cells’ anticancer functions. Data from my thesis indicates that folate receptor alpha (FRα) CAR-T cell antitumor effector function is enhanced, rather than suppressed by ACh. ACh promotes transient expression of human FOXP3 in activated proinflammatory effector T cells (Teffs) expressing interferon gamma (IFN-γ). My results identify the alpha 7 nicotinic acetylcholine receptor (α7 nAChR) is involved in increasing FOXP3, but not IFN-γ expression in human T cells and the enzyme choline acetyltransferase (ChAT) which catalyzes the rate-limiting step in the synthesis of ACh, is required for self-regulation of FOXP3 and the activation marker CD25 following activation. Helios, a transcription factor and Treg stability marker is likewise transiently expressed by active Teffs and only FOXP3+/Helios-, IFN-γ+ Teffs proliferate throughout expansion. Taken together, my results indicate that ACh signaling in vitro enhances T cell activation and differentiation into antitumor Teffs, and this could be used for novel methods to increase the efficiency of current solid cancer therapies through manipulation of FOXP3 and/or IFN-γ.



biochemistry, cancer, cancer biology, CAR-t cells, t cells, acetylcholine, flow cytometry, immunology, interferon gamma, IFN-g, foxp3, regulatory T cell, effector t cells, teff, treg, luciferase, ELISA, cytotoxicity