Antigen , mucosal delivery

Liposomes (see Chapter 9) have been used to deliver vaccines and have been observed to have immunostimulant activity. When administered orally liposomes with encapsulated antigens have been claimed to provide protection from the gastric proteolytic enzymes. Liposomes also have potential as mucosal delivery systems... 

Hu, K. F., Elvander, M., Merza, M., Akerblom, L., BrAndenburg, A., and Morein, B. (1998), The immunostimulatory complex (ISCOM) is an efficient mucosal delivery system for respiratory syncytial virus (RSV) envelope antigens inducing high local and systemic antibody responses, Clin. Exp. Immunol., 113, 235-243. 

Steidler, L., Robinson, K., Chamberlain, L., et al. (1998) Mucosal delivery of murine interleukin-2 (IL-2) and lL-6 by recombinant strains of Ixictococcus lactis coexpressing antigen and cytokine. Infect Immun 66, 3183-3189. 

Mestecky, J., Michalek, S. M., Moldoveanu, Z., and Russell, M. W. (1997). Routes of immunization and antigen delivery systems for optimal mucosal immune responses in humans. Behring Inst. Mitt. 98, 33-43. 

The induction of an immune response by various mucosal routes is an important approach for the control of mucosally acquired infections. The apparent linked nature of the mucosal immune system enables the delivery of an antigen to any mucosal surface to have the secondary effect of potentially inducing immunity at others. Induction of a combination of systemic and secretory immune responses can be determined by the nature of the antigen, the route of administration, and the delivery system utilized. For example, traditional parenteral vaccines primarily induce IgM and IgG responses, whereas mucosal vaccination can elicit both IgG and secretory IgA responses (Corthesy, 2007). 

It is of particular clinical relevance to test the effects of mucosal allergen application in already sensitized organisms. The obvious advantage of the use of so-called hypoallergenic molecules lies in their risk-free application. Thus, the practical consequences from such experimental studies could include the development of low-risk mucosal vaccines based on the induction of tolerance - with or without the use of certain mucosal antigen delivery systems. 

A wide variety of novel approaches for the development of mucosal immune responses by administration of antigens in different delivery systems have been investigated, in many cases, with considerable success. These approaches include (1) the coadministration of immunogens with adjuvants active at the mucosal surface, (2) the coupling of immunogens to carrier molecules that promote their uptake at the mucosal inductive site, and (3) the expression of antigens in live attenuated bacterial or viral vectors, which can promote the colonization of mucosal tissue and the incorporation of antigens into a variety of microparticulate and adhesive vehicles, which are taken up in mucosal inductive sites. 

Membranous epithelial M cells are a part of the organized mucosa-associated lymphoid tissue (O-MALT). These cells are specialized for antigen sampling. Also, they are exploited as a route of invasion by several pathogens.39 M cells are concentrated in follicle-associated epithelial (FAE) tissue called Peyer s patches in the small intestine. As M cells carry out endocytotic transport, they can be potential vehicles for mucosal drug and vaccine delivery. 

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