Recent Advances in Nanovaccines Using Biomimetic Immunomodulatory Materials

Vijayan, Veena; Mohapatra, Adityanarayan; Uthaman, Saji; Park, In-Kyu

The development of biomimetic NPs with chemical and structural modifications to mimic the biological environment is an established approach for cancer therapy. Nanovaccines are novel platforms for delivery of both adjuvants and antigens that generate a strong antitumor response by modulating the immune system [124] . Various type of nanovaccines, such as liposomes, protein NPs, and cell-membrane-coated nanomicelles, have been recently developed for successful anti-cancer therapy [125, 126] . The modification and surface functionalization of the biomimetic nanovaccines can accelerate therapeutic activity with high cellular uptake, prolonged circulation, site-specific accumulation, and stimuli-responsive drug releases. Phospholipids are the primary elements for liposome formulation, which mimics a biological membrane [127] . The formulation of an ILP by introducing specific antibodies and antigens onto the surface can induce active targeting and immune modulation [128] . Antigens presented in the liposomes induced immunogenicity inside the body. Encapsulated or surface modified antigens altered the T-cell responses and stimulated the CD4 + and CD8 + T-cells to fight the tumor. Phosphatidylserine conjugated liposomes are effective vaccines that are significantly captured by antigen-presenting cells, and are responsible for T h -cell proliferation [129] . Polyinosinic: polycytidylic acid (Poly I:C) mediated cationic liposome was reported as an adequate vaccine delivery against a natural epitope of HER/Neu-derived P5 peptide that enhances anti-tumor immunity. Poly (I:C) is a TLR 3 agonist that displays strong immune response and triggers apoptosis. The liposomal vaccination of both P5 peptide and Poly(I:C) significantly induced an antitumor immune response by releasing a higher number of CD8 + T-cells and interferon-gamma, compared to a single vaccination of either P5 peptide or Poly (I:C). Liposomal injection with P5 and Poly (I:C) induced a strong cytotoxic T lymphocyte (CTL) response, and inhibited tumor growth, compared to other controls [130] . P5 peptide conjugated liposomal delivery of monophosphoryl lipid A (MPLA), an TLR 4 agonist, enhances the secretion of IFN-γ and CTL response by inducing CD8 + T-cells. Liposomal vaccination with P5 and MPL achieves significant tumor inhibition and longer survival time [131] .