Activating Innate Immunity by a STING Signal Amplifier for Local and Systemic Immunotherapy

Area of Science:

• Biomedical Engineering
• Immunotherapy
• Nanotechnology

Background:

• Acquired immunotherapy benefits a limited patient population.
• Stimulator of interferon genes (STING) pathway activation is crucial for enhancing innate immunity and broad-spectrum immunotherapy.
• Developing novel strategies to amplify the STING pathway is essential for improving cancer treatment efficacy.

Purpose of the Study:

• To construct M@P@HA nanoparticles as a STING signal amplifier to enhance innate immunotherapy.
• To investigate the mechanism by which M@P@HA nanoparticles activate and amplify the STING signaling pathway in tumor cells and tumor-associated macrophages (TAMs).
• To evaluate the therapeutic potential of M@P@HA nanoparticles in activating innate immunity and promoting CD8+ T cell infiltration, particularly in tumors with low immunogenicity.

Main Methods:

• Construction of M@P@HA nanoparticles designed to decompose and release manganese ions (Mn2+) and protoporphyrin (PpIX).
• Utilizing light irradiation to generate reactive oxygen species, disrupting cellular redox homeostasis and releasing mitochondrial double-stranded (ds) DNA to initiate the STING signal.
• Assessing the synergistic effect of Mn2+ in boosting STING pathway components (cGAS and STING) in tumor cells and TAMs.
• Evaluating the activation of innate immunity and CD8+ T cell infiltration in tumor tissues following M@P@HA treatment.

Main Results:

• M@P@HA nanoparticles successfully triggered STING signal activation upon light irradiation.
• Manganese ions (Mn2+) significantly enhanced the activity of cGAS and STING, amplifying the STING signal in both tumor cells and TAMs.
• The treatment led to enhanced innate immune activation and substantial CD8+ T cell infiltration, even in tumors with low immunogenicity.
• M@P@HA nanoparticles demonstrated the ability to cascade immune responses, overcoming tumor-induced immunosuppression.

Conclusions:

• M@P@HA nanoparticles serve as an effective STING signal amplifier, enhancing innate immunotherapy.
• The dual action of releasing dsDNA and Mn2+ amplifies the STING pathway, promoting anti-tumor immunity.
• This approach holds promise for developing novel immunotherapies effective against a broader range of cancers, including those with low immunogenicity.