A d-peptide-based oral nanotherapeutic modulates the PD-1/PD-L1 interaction for tumor immunotherapy.

BACKGROUND

PD-1/PD-L1 immune checkpoint inhibitors are currently the most commonly utilized agents in clinical practice, which elicit an immunostimulatory response to combat malignancies. However, all these inhibitors are currently administered injection using antibody-based therapies, while there is a growing need for oral alternatives.

METHODS

This study has developed and synthesized exosome-wrapped gold-peptide nanocomplexes with low immunogenicity, which can target PD-L1 and activate antitumor immunity through oral absorption. The PDL1 was characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and gel silver staining. The transmembrane ability of PDL1 was evaluated by flow cytometry and immunofluorescence. Cell viability was determined using the Cell Counting Kit-8 (CCK-8) assay. ELISA experiments were conducted to detect serum and tissue inflammatory factors, as well as serum biochemical indicators. Tissue sections were stained with H&E for the evaluation of the safety of PDL1. An MC38 colon cancer model was established in immunocompetent C56BL/6 mice to evaluate the effects of PDL1 on tumor growth . Immunohistochemistry (IHC) staining was performed to detect cytotoxicity factors such as perforin and granzymes.

RESULTS

First, PDL1 was successfully synthesized, and milk exosome membranes were encapsulated through ultrasound, repeated freeze-thaw cycles, and extrusion, resulting in the synthesis of PDL1. Multiple characterization results confirmed the successful synthesis of PDL1 nanoparticles. Furthermore, our data demonstrated that PDL1 exhibited excellent colloidal stability and superior cell transmembrane ability. and experiments revealed that PDL1 did not cause damage to multiple systemic organs, demonstrating its good biocompatibility. Finally, in the MC38 colon cancer mouse model, it was discovered that PDL1 could inhibit the progression of colon cancer, and this tumor-suppressive effect was mediated through the activation of tumor-specific cytotoxic T lymphocyte (CTL)-related immune responses.

CONCLUSION

This study has successfully designed and synthesized an oral nanotherapeutic, PDL1, which demonstrates small particle size, excellent colloidal stability, transmembrane ability in tumor cells, and biocompatibility. experiments have shown that it effectively activates T-cell immunity and exerts antitumor effects.