PEG modified liposomes containing CRX-601 adjuvant in combination with methylglycol chitosan enhance the murine sublingual immune response to influenza vaccination

Abstract

The mucosa is the primary point of entry for pathogens making it an important vaccination site to produce a protective mucosal immune response. While the sublingual (SL) mucosa presents several barriers to vaccine penetration, its unique anatomy and physiology makes it one of the best options for mucosal vaccination. Efficient and directed delivery of adjuvants and antigens to appropriate immune mediators in the SL tissue will aid in development of effective SL vaccines against infectious diseases. Herein we demonstrate a robust immune response against influenza antigens co-delivered sublingually with engineered liposomes carrying the synthetic toll like receptor-4 agonist, CRX-601. Liposome modification with PEG copolymers (Pluronics), phospholipid- PEG conjugates and chitosan were evaluated for their ability to generate an immune response in a SL murine influenza vaccine model. Phospholipid-PEG conjugates were more effective than Pluronic copolymers in generating stable, surface neutral liposomes. SL vaccination with surface modified liposomes carrying CRX-601 adjuvant generated significant improvements in flu-specific responses compared to unmodified liposomes. Furthermore, the coating of modified liposomes with methylglycol chitosan produced the most effective flu-specific immune response. These results demonstrate efficient SL vaccine delivery utilizing a combination of a mucoadhesive and surface neutral liposomes to achieve a robust mucosal and systemic immune response.

Mucosal Vaccine Development Based on Liposome Technology

“…Finally, many other modifications can be made to liposomes that further extend the high versatility of these nanoparticles. Such modification includes the attachment of targeting agents such as galactose or APC-specific antibodies, of polymers, for example, poly(ethyleneglycol), or the addition of different kinds of coatings such as chitosan [38, 54–58]. Furthermore, when introduced into a physiological fluid, nanoparticles such as liposomes acquire a dynamic layer of adsorbed proteins in a corona, the nature of which is determined by both the particle's size and surface properties as well as the shear stress the particle is exposed to [59–62].…”

“…Alternatively, such modifications can also transiently open tight junctions between epithelial cells to allow for transmucosal transport of the liposomes [80–82]. In fact, chitosan-coated liposomes have been shown to give better serum IgG antibody levels compared to other bioadhesive polymers, such as hyaluronic acid or carbopol coated liposomes, and host much better immunogenicity than uncoated negative, neutral, or positively charged liposomes [38, 56–58]. …”

“…Indeed, tight junctions were reported to be open when using PC/Chol-liposomes or Tremella -coated liposomes [84]. Enhanced immune responses were also observed with mucus-penetrating liposomes made with poly(ethylene glycol) (PEG) or the PEG-copolymer pluronic [38]. Significantly higher specific IgA and IgG antibody levels were found with PEGylated than un-PEGylated liposomes.…”

Commentary on the Development and Application of Chitosan in Immunochemistry

“…Approaches based on combined use of delivery systems and adjuvants are being favored to maximize efficient delivery of antigens [13]. The efficacy of methylglycol chitosan was evaluated for improving systemic and mucosal immune responses to a monovalent detergentsplit fluvirus vaccine.…”

Porous Inorganic Drug Delivery Systems—a Review

“…Moreover, several unorthodox strategies have been explored to utilise structures on the nano-and micro-meter scales that are promising candidates and emerging systems for drug delivery. These include microspheres (8,9), dendrimers (10,11), nano-particles (12,13), nano-emulsions (14,15), nano-fibers (16,17), micelles (18), niosomes (19,20), liposomes (21,22) and proniosomes (23,24).…”