Intracellular Delivery of a Protein Antigen With an Endosomal-Releasing Polymer Enhances CD8 T-cell Production and Prophylactic Vaccine Efficacy

Bioconjug Chem. 2010 Dec 15;21(12):2205-12. doi: 10.1021/bc100204m. Epub 2010 Nov 2.

Abstract

Protein-based vaccines have significant potential as infectious disease and anticancer therapeutics, but clinical impact has been limited in some applications by their inability to generate a coordinated cellular immune response. Here, a pH-responsive carrier incorporating poly(propylacrylic acid) (PPAA) was evaluated to test whether improved cytosolic delivery of a protein antigen could enhance CD8+ cytotoxic lymphocyte generation and prophylactic tumor vaccine responses. PPAA was directly conjugated to the model ovalbumin antigen via reducible disulfide linkages and was also tested in a particulate formulation after condensation with cationic poly(dimethylaminoethyl methacrylate) (PDMAEMA). Intracellular trafficking studies revealed that both PPAA-containing formulations were stably internalized and evaded exocytotic pathways, leading to increased intracellular accumulation and potential access to the cytosolic MHC-1 antigen presentation pathway. In an EG.7-OVA mouse tumor protection model, both PPAA-containing carriers robustly inhibited tumor growth and led to an approximately 3.5-fold increase in the longevity of tumor-free survival relative to controls. Mechanistically, this response was attributed to the 8-fold increase in production of ovalbumin-specific CD8+ T-lymphocytes and an 11-fold increase in production of antiovalbumin IgG. Significantly, this is one of the first demonstrated examples of in vivo immunotherapeutic efficacy using soluble protein-polymer conjugates. These results suggest that carriers enhancing cytosolic delivery of protein antigens could lead to more robust CD8+ T-cell response and demonstrate the potential of pH-responsive PPAA-based carriers for therapeutic vaccine applications.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acrylates / chemistry
  • Acrylates / metabolism
  • Animals
  • Antigen Presentation / immunology
  • Antigens / administration & dosage*
  • Antigens / immunology
  • Antigens / metabolism
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • Cancer Vaccines / immunology*
  • Cancer Vaccines / metabolism
  • Cell Proliferation
  • Disease-Free Survival
  • Drug Delivery Systems / methods*
  • Endosomes / immunology*
  • Endosomes / metabolism
  • Female
  • Hydrogen-Ion Concentration
  • Immunoglobulin G / analysis
  • Immunoglobulin G / biosynthesis
  • Lymphocyte Activation / immunology
  • Methacrylates / chemistry
  • Methacrylates / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Neoplasm Transplantation
  • Nylons / chemistry
  • Nylons / metabolism
  • Ovalbumin / administration & dosage*
  • Ovalbumin / immunology
  • Ovalbumin / metabolism
  • Polymers / chemistry
  • Polymers / metabolism
  • Thymoma / mortality
  • Thymoma / therapy
  • Thymus Neoplasms / mortality
  • Thymus Neoplasms / therapy
  • Treatment Outcome

Substances

  • Acrylates
  • Antigens
  • Cancer Vaccines
  • Immunoglobulin G
  • Methacrylates
  • Nylons
  • Polymers
  • poly(2-(diethylamino)ethyl methacrylate)
  • Ovalbumin
  • acrylic acid