Mucosal epithelial cells, adhesion

E-cadherin is unique in that it not only, like other cadherin family members, mediates homophilic adhesion to establish and maintain cellcell contacts, it also serves as a counter-receptor for integrins Oe/37 (Cepek et al, 1994) and (Whittard et al, 2002) in heterophilic adhesion. In fact, the interaction between E-cadherin on mucosal epithelial cells and Oe/S on intraepithelial lymphocytes has been the best characterized tissue-specific interaction for lymphocyte retention. Although structure of binding domains between E-cadherin and is not available, mutagenesis... 

The failure in increasing residence time of mucoadhesive systems in the human intestinal tract has led scientists to the evaluation of multifunctional mucoadhesive polymers. Research in the area of mucoadhesive drug delivery systems has shed light on other properties of some of the mucoadhesive polymers. One important class of mucoadhesive polymers, poly(acrylic acid) derivatives, has been identified as potent inhibitors of proteolytic enzymes [72-74]. The interaction between various types of mucoadhesive polymers and epithelial cells has a direct influence on the permeability of mucosal epithelia by means of changing the gating properties of the tight jrmctions. More than being only adhesives, some mucoadhesive polymers can therefore be considered as a novel class of multifunctional macromolecules with a number of desirable properties for their use as delivery adjuvants [72,75]. 

In both S. pneumoniae and N. meningitidis, the thickness of the capsule has been shown to vary at different points in infection. In Neisseria meninigitidis decreased capsule production enhances tissue invasion, while increased capsule production is essential for survival in systemic infections [349]. Likewise, studies in pneumococci have suggested that the capsule prevents bacterial adhesion to epithelial cells, as well as to endothelial cells [350,351,352]. Bacteria producing less capsular polysaccharide more efficiently colonize mucosal surfaces, while those producing more capsule are more virulent in systemic infections [350,353]. 

First contact between the intestinal microbiota and the host occurs via mucosal ECs (or modified epithelial cells called M cells in the Peyer s Patches), and underlying or intercalating DCs. Mucosal ECs express polymeric immunoglobulin receptor (PigR) and secretary component, MHC class I and II molecules, other adhesion molecules and a variety of cytokines and chemokines. These molecules play important roles in signaling microbial... 

The apparent ease with which cholera vibrios migrate through the intestinal mucus suggests that there is little permanent adhesion of the bacterium to this layer. Microscopical examination of cholera-infected rabbit intestine reveals large numbers of vibrios attached to the brush border surfaces of intestinal epithelial cells, but no evidence of fimbriae can be seen. There appear to be at least two highly specific receptors for the cholera vibrio on the mucosal surface, one of which is fucose-sensitive and located on the brush border epithelium. The location of the second fucose-resistant binding site is unclear. V. cholerae, like many other vibrios, produce a protein-rich slime capsule. There is no evidence that this layer has any adhesive properties, indeed the reverse may be true, since slime production and haemagglutinating activities are inversely related. 

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