Enhancing oral vaccine potency by targeting intestinal M cells

Abstract

The immune system in the gastrointestinal tract plays a crucial role in the control of infection, as it constitutes the first line of defense against mucosal pathogens. The attractive features of oral immunization have led to the exploration of a variety of oral delivery systems. However, none of these oral delivery systems have been applied to existing commercial vaccines. To overcome this, a new generation of oral vaccine delivery systems that target antigens to gut-associated lymphoid tissue is required. One promising approach is to exploit the potential of microfold (M) cells by mimicking the entry of pathogens into these cells. Targeting specific receptors on the apical surface of M cells might enhance the entry of antigens, initiating the immune response and consequently leading to protection against mucosal pathogens. In this article, we briefly review the challenges associated with current oral vaccine delivery systems and discuss strategies that might potentially target mouse and human intestinal M cells.

Figure 1. Schematic diagram of intestinal epithelium showing M cells, Peyer's patches, intestinal epithelial cells, and pathway of Ag transport.

DC, dendritic cells; IEC, intestinal epithelial cell (NU, nucleus); MC, M cell; IEL, intra epithelial lymphocytes; PP, Peyer's patches; MΦ, macrophages; Pv, particulate Ag in pinocytic vesicle of M cell.