Chitosan

Abstract

The nasal route is attractive for the delivery of vaccines in that it not only offers an easy to use, non-invasive, needle-free alternative to more conventional parenteral injection, but it also creates an opportunity to elicit both systemic and (crucially) mucosal immune responses which may increase the capability of controlling pathogens at the site of entry. Immune responses to "naked" antigens are often modest and it is widely accepted that incorporation of an adjuvant is a prerequisite for the achievement of clinically effective nasal vaccines. Many existing adjuvants are sub-optimal or unsuitable because of local toxicity or poor enhancement of immunogenicity. Chitosan, particularly chitosan salts, have now been used in several preclinical and clinical studies with good tolerability, excellent immune stimulation and positive clinical results across a number of infections. Particularly significant evidence supporting chitosan as an adjuvant for nasal vaccination comes from clinical investigations on a norovirus vaccine; this demonstrated the ability of chitosan (ChiSys®), when combined with monophosphoryl lipid, to evoke robust immunological responses and confer protective immunity following (enteral) norovirus challenge. This article summarizes the totality of the meaningful information (including key unpublished data) supporting the development of chitosan-adjuvanted vaccines.

Harnessing Nanoparticles for Immunomodulation and Vaccines

“…Examples of the former are polystyrene, and PLGA ( dl -Lactic co-glycolic acid), which were reported to be efficacious in delivering and promoting controlled release of growth hormone in monkeys as well as exhibiting adjuvant functions [27]. Examples of naturally occurring polymers forming NPs are pullulan (CHP) [30] as well as nanogels derived from chitosan, both of which have been reported to be highly potent as adjuvants [31]. Chitosan has been used in humans as an excipient in a number of formulations and has shown good tolerability and low toxicity [32].…”

Eco‐Friendly and Facile Preparation of Spherical Chitin Nanoparticles

“…Chitosan is used to coat quantum dots for bioimaging a in cancer diagnosis . Chitosan derivatives as vaccine adjuvants enhance immune responses against pathogenic microorganisms . The growth of Escherichia coli is inhibited in the presence of chitosan with a concentration greater than 0.025%.…”

Alkyl polyglycoside, a highly promising adjuvant in intranasal split influenza vaccines

“…While CS is often used as an adjuvant in i.n. vaccines, its mechanism of action is not fully understood, 26 but likely function is to reduce the clearance of administered formulations from the nasal cavity 27 and/or facilitate antigen uptake into NALT through its transient effect on epithelial tight junctions. CS is also reported to exhibit immunomodulatory properties, such as natural killer (NK) cell and macrophage stimulation.…”