NF1 Leucine Rich Domain-Derived Extracellular Vesicles Remodel the Glioblastoma Immune Microenvironment via an ADAM17-Associated Inflammatory Program.

Extracellular vesicles (EVs) are increasingly recognized as mediators of intercellular communication in cancer. We previously demonstrated that re-expression of the leucine-rich domain (LRD) of neurofibromin (NF1) suppresses glioblastoma (GBM) invasion and limits microglia/macrophage infiltration into the tumor microenvironment (TME). Given the central role of tumor-associated microglia/macrophages (TAMs) in GBM progression, we investigated whether NF1-LRD-containing EVs (NF1-LRD-EVs) could modulate TAM function and remodel the TME. Our results showed that NF1-LRD-EVs attenuated microglia and macrophage recruitment in migration assays, consistent with reduced microglia/macrophage recruitment observed in vivo. In parallel, treatment with NF1-LRD-EVs enhanced phagocytic activity of both microglia and iPSC-derived macrophages, accompanied by induction of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, and downregulation of immunosuppressive mediators such as Arginase-1 and IL-10. Mechanistically, NF1-LRD-EVs induced ADAM17-associated inflammatory signaling, accompanied by NF-κB activation. Pharmacological inhibition of ADAM17 reduced TNF-α release and attenuated NF-κB activation, supporting a role for ADAM17-dependent signaling in amplifying this inflammatory response. Together, these findings show that NF1-LRD-EVs reprogram TAMs toward a pro-inflammatory phenotype and modulate the GBM immune microenvironment. These results provide a framework for understanding NF1-LRD-EV-mediated immune regulation and support further investigation of EV-mediated immune modulation of the TME.