Enhanced Antigen Capture via Cholinephosphate-Mediated Cell Membrane Interactions to Improve In Situ Tumor Vaccines

Nanoscience Chemistry Immunology Life Sciences Oncology Bioengineering Medicine Basic Medical Sciences
cholinephosphate cell membrane interactions antigen capture tumor vaccines immunotherapy photothermal effect immune suppression alleviation

Enhanced Antigen Capture via Cholinephosphate-Mediated Cell Membrane Interactions

Choline Phosphate-Based Antigen Capture Strategy Boosts In Situ Tumor Vaccine Research: A Novel Immunotherapy Approach

In the field of cancer immunotherapy, in situ tumor vaccines have garnered significant attention for their ability to harness a patient’s immune system to target tumors. However, challenges remain in their clinical application. To address the issues of low antigen capture efficiency and insufficient activity of antigen-presenting cells (APCs) leading to suboptimal immune responses, this study published in Advanced Healthcare Materials proposes an innovative approach. Jointly conducted by researchers from Jinan University, Hunan University of Chinese Medicine, and Guangzhou Medical University, and published in 2025, the study focuses on leveraging cholinephosphate-mediated cell membrane interactions to enhance antigen capture efficiency, thereby improving the efficacy of tumor vaccines.

Background and Research Motivation

In recent years, cancer immunotherapy has become a major pillar of cancer treatment research. Among these, in situ tumor vaccines stand out as an innovative therapy capable of inducing targeted immune responses against tumors. The mechanism involves inducing localized tumor cell death to release tumor-associated antigens (TAAs), which are subsequently captured and presented by APCs to activate a tumor-specific immune response. However, the low efficiency of antigen capture and presentation often limits the vaccine’s effectiveness.

Current research has attempted to address this by using functional nanocarriers to deliver tumor antigens and employing 3D hydrogel networks to capture these antigens. Nonetheless, capturing lipid bilayer-embedded tumor cell membrane antigens (water-insoluble antigens) remains an unsolved challenge. Furthermore, a pathogen-mimicking approach to simultaneously capture water-soluble and insoluble tumor antigens for efficient APC presentation is still lacking. This study proposes a choline phosphate-mediated antigen capture strategy, developing a novel in situ tumor vaccine platform to overcome these barriers.

Study Design and Workflow

Method Overview

The study centers on the development of an improved in situ tumor vaccine based on manganese-mineralized black phosphorus (MNBP) nanoparticles and poly(glutamic acid-cholinephosphate) (PgluCP) for antigen capture. The research encompasses the following key steps:

  1. Synthesis and Modification of MNBP:

    • Black phosphorus (BP) nanosheets were prepared using solvent exfoliation. N-methyl-2-pyrrolidone (NMP) was employed for ultrasonic exfoliation. Ammonia and manganese chloride (MnCl2) were then added to achieve manganese phosphate deposition on the BP surface, yielding MNBP nanoparticles.
    • Optimization of exfoliation time and solvent conditions, followed by characterization using transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR), confirmed the morphology and composition of the nanoparticles. The selected MNBP had an optimal size of ~340 nm and demonstrated exceptional photothermal properties.

  2. Fabrication of MNBP@PgluCP Composite Materials:

    • Charge interaction was utilized to coat negatively charged MNBP with the cationic polymer PgluCP. Proton nuclear magnetic resonance (1H NMR) was used to verify the structural characteristics of PgluCP. Optimal binding efficiency was achieved with a mass ratio of 1:6 between MNBP and PgluCP.

  3. Photothermal and Immunogenicity Characterization:

    • Photothermal analysis of MNBP demonstrated its ability to stably increase temperature to 43°C under 1.5 W cm−2 laser irradiation, with outstanding thermal stability over multiple heating/cooling cycles. Tumor antigens (TAAs) and immunogenic cell death (ICD)-related danger-associated molecular patterns (DAMPs) such as HMGB1, ATP, and CRT were evaluated via in vitro experiments.

  4. Antigen Capture and Presentation:

    • Using SDS-PAGE and protein quantification, the study confirmed that MNBP@PgluCP significantly enhanced the capture of both water-soluble and water-insoluble antigens compared to bare MNBP. Bone marrow-derived dendritic cells (BMDCs) were used to validate the enhanced antigen presentation and maturation facilitated by this complex.

  5. In Vivo Immune Activation Assessment:

    • Using unilateral and bilateral mouse tumor models, the study evaluated the photothermal therapeutic and immunostimulatory effects of the composite nanoparticles. Fluorescence imaging confirmed nanoparticle retention at tumor sites, and flow cytometry and ELISA demonstrated DC maturation, CD8+ T cell infiltration, and cytokine secretion levels.

Results and Findings

Experimental Data and Results Analysis

  • Photothermal Effect: MNBP@PgluCP stably elevated local temperatures to 43°C under laser irradiation at 1.5 W cm−2, triggering ICD and releasing DAMPs.
  • Antigen Capture: Quantified by protein electrophoresis and BCA assays, MNBP@PgluCP captured 1.8 times more protein than unmodified MNBP.
  • Antigen Presentation: In BMDC assays, MNBP@PgluCP significantly enhanced the expression of APC surface markers such as CD80 and CD86, while effectively promoting T cell activation.
  • Immune Activation In Vivo:
    • Laser irradiation enhanced CD8+ T cell infiltration at the tumor site and caused significant tumor necrosis in both primary and distant tumors.
    • Combining MNBP@PgluCP with anti-PD-1 antibody yielded a dramatic synergistic effect, effectively suppressing distant tumor growth.

Research Significance and Innovations

  1. Innovative Antigen Capture Strategy: The choline phosphate-based mechanism significantly improved the diversity and efficiency of tumor antigen capture.
  2. Photothermal-Immunotherapy Synergy: Combining mild photothermal therapy with immune activation not only enhanced local tumor treatment but also stimulated systemic anti-tumor immune responses.
  3. Immune Checkpoint Inhibition Synergy: Incorporation of anti-PD-1 reversed tumor immune tolerance, providing theoretical support for advancing in situ tumor vaccine strategies.
  4. Broad Application Potential: Direct in vivo capture of heterogeneous tumor antigens offers tremendous clinical translational potential.

Conclusion

This study introduces a choline phosphate-mediated antigen capture method to revolutionize in situ tumor vaccine design. The developed photothermal-immunotherapy hybrid platform based on MNBP@PgluCP-αPD-1 not only addresses multiple technical bottlenecks but also paves the way for new advancements in cancer immunotherapy, demonstrating profound scientific value and clinical significance.