Polyanhydride-releasing oral microparticle technology (PROMPT) as a strategy for subunit vaccine administration

摘要

Our work addresses two priority objectives of next-generation vaccine research to achieve safe, cost-effective and easily distributable vaccines: 1) development of non-syringe delivery mechanism, and 2) immunization with subunit vaccines. Oral vaccines improve ease of administration and confer protection at mucosal surfaces for stronger immune response. Subunit vaccines (e.g. protein antigens) are desirable to overcome safety issues associated with current attenuated or inactivated oral vaccines, but are weakly immunogenic and poorly absorbed, requiring careful delivery considerations. Our proposed solution is PROMPT: Polyanhydride-Release Oral MicroPartide Technology. PROMPT is composed of a pH-responsive biodegradable platform based on polyethylene glycol) and polyjmethacrylic acid), designed to protect a payload of polyanhydride nanovaccines (PNVs) through the harsh conditions of the gastrointestinal tract for selective release in the small intestine, proximal to antigen-sampling M cells. The PNVs, based on 1,6-bis-(p-carboxyphenoxy)hexane (CPH) and sebacic acid (SA), serve simultaneously as adjuvant and delivery vehicle of subunit antigens, demonstrating enhanced antigen presentation and stimulation of antigen presenting cells, critical components in initiating immune response. In these studies, the dual-release platform has been evaluated for selective delivery and uptake in appropriate intestinal conditions. Microgels were first modified with biodegradable crosslinker, N,O-dimethacrylyol hydroxylamine (DMHA), which selectively degrades at neutral pH, coinciding with particle swelling in the intestine. PNVs synthesized by ant-solvent precipitation and encapsulating the subunit antigen are incorporated into microgels during UV-initiated free radical polymerization. Surface functionalization of nanoparticles with polyethylene glycol) and trehalose, performed by an amine-carboxylic acid coupling reaction demonstrate improved encapsulation during microgels synthesis while maintaining substantial internalization by macrophage cells as comparable to unmodified PNPs. Degradation studies in intestinal conditions indicate therapeutic release within a physiologically relevant timescale (e.g. 2-6 hours residence time), tunable by modifying crosslinker density (Figure 1). Upon depot release from the microgel, PNVs must transcytose the intestinal lumen to the underlying lymphoid to generate an immune response. PNV transport and targeting were confirmed in an in vitro model of human M cells (Figure 2). Figure 1. Fraction mass remaining of degradable hydrogels. Degradation is tunable by modifying crosslinking density. Figure 2. Nanovaccines localize near M cells in an in vitro M cell model (green-PNVs, yellow-M cell, red-membrane, blue-nuclei). Results indicate pH-responsive biodegradable microgels successfully protect and release PNVs in appropriate intestinal conditions. PNV surface functionalization improves PROMPT synthesis and, more importantly, does not adversely affect uptake by immune cells, including internalization by macrophages and transport in in vitro M cell model. Together, these studies demonstrate PROMPT has potential as an adaptable platform for oral vaccine administration.