NGR-modified cancer-associated fibroblast-derived exosomes deliver resveratrol to inhibit CXCR2/NF-κB signaling in myeloid-derived suppressor cells and reverse immune suppression in liver cancer.

OBJECTIVE: This study aimed to develop NGR (Asn-Gly-Arg) peptide-modified cancer-associated fibroblast (CAF)-derived exosomes for resveratrol delivery (NGR-Exos@Res) to target myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. By inhibiting the CXCR2/NF-κB pathway, this strategy reprograms MDSC function, reverses immune suppression, restores CD8+ T-cell antitumor activity, and suppresses liver cancer (LC) progression.

METHODS: Network pharmacology and molecular docking identified CXCR2 as a key Res target. Public scRNA-seq data analyzed MDSC-T-cell interactions in LC. Bone marrow-derived MDSCs were treated with Res in vitro; effects on CXCR2/immunosuppressive molecules were assessed via Western blot/immunofluorescence. A CAF line expressing 3×His-NGR-CD63 was generated to produce NGR-Exos loaded with Res (NGR-Exos@Res). Their toxicity, uptake, and biodistribution were evaluated. Efficacy was tested in a murine LC xenograft model, assessing MDSC function, T-cell activation, and immune evasion.

RESULTS: Single-cell transcriptomic analysis revealed that CXCR2 was highly expressed in MDSCs within HCC tissues. Moreover, inhibitory ligand-receptor pairs such as MIF-(CD74+CXCR4) were significantly activated in the interaction network between MDSCs and T cells. In vitro experiments demonstrated that resveratrol markedly downregulated the expression of CXCR2, Arg-1, and iNOS in MDSCs, thereby suppressing their proliferation while enhancing CD8+ T-cell proliferation and IFN-γ secretion. The successfully constructed NGR-Exos@Res drug delivery system exhibited a drug encapsulation efficiency of 19.3% and improved serum stability. In vivo, treatment with NGR-Exos@Res significantly reduced tumor volume, inhibited the CXCR2/NF-κB signaling pathway, decreased the proportion of MDSCs, and enhanced CD8+ T-cell activity.

CONCLUSION: In this study, we successfully constructed NGR peptide-modified Exos derived from CAFs for the targeted delivery of Res. This work innovatively proposes a novel immunotherapeutic strategy that targets tumor-associated MDSCs rather than directly killing tumor cells. Mechanistically, we identify and validate CXCR2 as a previously unrecognized functional target of resveratrol in MDSCs, through which resveratrol suppresses NF-κB signaling and reprograms MDSC function. Collectively, NGR-Exos@Res represents a precise and efficient delivery platform capable of reversing the immunosuppressive microenvironment in LC and provides a promising combinatorial strategy to overcome immunotherapy resistance by targeting immunosuppressive myeloid cells.