T2D-associated exosomes induce ER stress and metabolic reprogramming in tumor CD8+ T cells 9231

Description Tumor-infiltrating lymphocytes (TILs) are critical for anti-tumor immunity but are frequently impaired in the tumor microenvironment (TME). Immunotherapies aimed at reversing this dysfunction often fail, particularly in women with comorbid, obesity-driven type 2 diabetes (T2D), the most prevalent metabolic disorder. We developed a novel approach to generate patient-derived organoids (PDOs) from breast tumors that preserve native TIL populations for the first time. Previously, we demonstrated that exosomes from T2D patient plasma reprogram PDOs, driving immune evasion via expansion of dysfunctional T cells (Abstract ID: 2078). Here, we elucidate the molecular mechanisms underpinning this dysfunction using single-cell RNA sequencing. Pseudotime analysis revealed that CD8+ TILs exposed to T2D-derived exosomes deviate from normal activation and differentiation trajectories. Pathway hyperenrichment of this branch point identified significant upregulation of metabolic and endoplasmic reticulum (ER) stress circuits, along with increased apoptosis and immune checkpoint signaling. Differential gene expression highlighted suppression of IL7R, GZMK, and TBX21, key mediators of T cell differentiation and function. These results establish ER stress and metabolic dysregulation as key drivers of CD8+ T cell dysfunction in the TME in models of comorbid T2D. Targeting these pathways offers a promising strategy to restore T cell functionality and improve immunotherapy outcomes in breast cancers. Funding Sources This work was supported by grants from NIH: U01CA182898, U01CA243004 and R01CA222170 to G.V. Denis; 5T32AI007309 (PI: Gummurulu) to C.S. Ennis.