Autofluorescence lifetime imaging reveals links between cancer cell metabolism and immunosuppressive response 3347

Abstract Description Programmed Cell Death Ligand 1 (PD-L1) expression on tumor cells suppresses T cell function by binding to PD-1 receptors, limiting immunotherapy efficacy against solid tumors. While PD-L1 can be induced by inflammatory cytokines like interferon gamma (IFN-γ) from activated T cells, the role of cancer cell metabolism in this process remains unclear. Optical metabolic imaging (OMI) is a non-invasive technique to monitor cell metabolism via the autofluorescence lifetime of NAD(P)H. Here, we used OMI to study the effects of IFN-γ and activated T cell secretome on PD-L1 expression and metabolism in three human cancer cell lines: PANC-1 (pancreatic cancer), CHLA-20 (neuroblastoma), and HeLa (cervical cancer). We also tested if glycolytic inhibition affected PD-L1 expression. In CHLA-20 and HeLa cells, we observed a significant increase in PD-L1 expression and decrease in NAD(P)H mean lifetime (τm) - indicating a metabolic shift toward glycolysis - upon exposure to IFN-γ and activated T cell secretome. Glycolysis inhibition (2DG) reduced PD-L1 expression in these cells. Conversely, PANC-1 cells exhibited no change in PD-L1 expression and increased NAD(P)H τm after IFN-γ treatment, while activated T cell secretome resulted in no changes in PD-L1 expression or NAD(P)H τm. Using OMI, we characterized the relationship between glycolysis, PD-L1 expression, and cancer response to inflammatory signals, highlighting cancer metabolism as a potential target to improve immunotherapy efficacy. Funding Sources Supported by Hilldale Felloship; Morgridge Institute for Research; Sophomore Research Fellowship. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)