Liposome-based immunity-inducing systems for cancer immunotherapy

Abstract

Cancer immunotherapy has gained much attention for next-generation cancer treatment. To conduct cancer immunotherapy, efficient antigen delivery systems must be able to deliver an antigen selectively to antigen-presenting cells, release it at suitable sites for induction of cross-presentation, and simultaneously induce activation of immunocompetent cells. Liposomes are a candidate for use as such multifunctional antigen delivery carriers because of their capability for easy functionalization. This review describes the rational design of liposome-based antigen delivery systems. Surface modification of liposomes by pH-responsive or fusogenic materials can achieve cytoplasmic delivery of antigen, leading to cross-presentation of exogenous antigen via a "cytosolic pathway." In contrast, targeting surface receptors on antigen presenting cells or the selective release of antigen in early endosome induced "vacuolar pathway"-mediated cross-presentation. Introduction of adjuvant molecules such as Toll like receptor agonists, synthetic cationic lipids or bioactive polysaccharides to liposomes improved their immunity-inducing ability. Combination with cancelling systems of immunosuppression in tumor microenvironment enhanced antitumor immunity of antigen delivery systems. Further understanding of immunity-inducing mechanism and molecular basis of tumor immunosuppressive environments and purposeful design of liposome-based antigen delivery systems can provide effective immunity-inducing systems for cancer immunotherapy.

Materials for Immunotherapy

“…The shell material is typically made by the self‐assembly amphiphilic materials (e.g., lipid, polymer, or protein) such that the core is an aqueous‐rich reservoir of hydrophilic moieties. A major advantage of this class of materials is that they enable: i) the encapsulation of high payloads, ii) the incorporation of hydrophilic species (e.g., proteins and nucleic acids), and iii) the protection of said species from degradation or denaturation that can occur during preparation and administration . The most studied type of nanocapsule is the liposome, which is comprised of lipid building blocks.…”

“…A major advantage of this class of materials is that they enable: i) the encapsulation of high payloads, ii) the incorporation of hydrophilic species (e.g., proteins and nucleic acids), and iii) the protection of said species from degradation or denaturation that can occur during preparation and administration. [117] The most studied type of nanocapsule is the liposome, [118] which is comprised of lipid building blocks. However, nanocapsules can be made from a wide variety of materials that we explore in the following sections.…”

<p>Preparation, Characterization, and Pharmacokinetic Study of a Novel Long-Acting Targeted Paclitaxel Liposome with Antitumor Activity</p>

“…The use of liposomes as drug carriers for chemotherapy was first proposed in 1974 by Gregoriadiset al 13 and liposomes are regarded as good candidates because of their safety, size controllability, and capability for easy functionalization. 14 Cisplatin and other chemotherapeutic drug-liposome preparations are approved by the FDA for clinical use in tumor therapy. 15 The study of polyethylene glycol (PEG) long-circulating liposomes began in 1990.…”

Cryo-EM sample preparation method for extremely low concentration liposomes

“…Liposomes are widely used as carrier systems in pharmaceutics (e.g. encapsulate therapeutic agents for cancer therapy (Børresen et al, 2018;Yuba, 2018;Zununi Vahed et al, 2017) and for neurological diseases (Vieira and Gamarra, 2016)), food industries (e.g. encapsulate bioactive food compounds to improve flavoring and nutritional properties or protect the food from spoilage and degradation (Shukla et al, 2017) ) and cosmetics (e.g.…”