Biological role of Ep-CAM in the physical interaction between epithelial cells and lymphocytes in intestinal epithelium

The mucosal epithelium including intestinal epithelial cells (IECs) and intraepithelial lymphocytes (IELs) provide a first line of defense in the gastrointestinal tract. However, limited information is currently available concerning the nature of the physical interaction molecule that interconnects IECs and IELs. Among the several monoclonal antibodies (mAbs) generated by immunizing porcine IECs, mAb (5-15-1) was shown to strongly react with IELs in addition to IECs. MALDI-TOF-MS and tandem MS analysis suggested that the antigen belongs to a family of human homophilic epithelial cell adhesion molecule (Ep-CAM). The amino acid sequence of porcine Ep-CAM showed 82.8%, 78.1%, and 76.8% homology compared to human, mouse, and rat Ep-CAM. Moreover, 5-15-1 specifically reacted with transfectant of porcine Ep-CAM. These data suggest that the Ep-CAM may act as a physical homophilic interaction molecule between IELs and IECs at the mucosal epithelium for providing immunological barrier as a first line of defense against mucosal infection.

Intranasal immunization with outer membrane protein P6 and cholera toxin induces specific sinus mucosal immunity and enhances sinus clearance of nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is one of the leading pathogens in sinusitis. One of the outer membrane proteins of NTHi, P6, is a common antigen to all strains and is an attractive candidate for a subunit bacterial vaccine. In this study, we characterized normal sinus mucosa (SM) and investigated the potential of intranasal immunization with P6 and cholera toxin (CT) for induction of mucosal protective immunity against NTHi in the maxillary sinuses of rats. Intranasal immunization induced P6-specific sinus mucosal and systemic immunological responses, mainly of the IgA and IgG isotype. The protective effect of intranasal immunization was demonstrated by enhancement of sinus clearance of NTHi. The present study showed that unilateral intranasal immunization has a capacity to induce protective immunity against NTHi in the bilateral maxillary sinuses. Systemic administration of the vaccine did not affect sinus clearance of NTHi. These findings suggest that a nasal vaccine might be useful for preventing sinusitis.

Mucosal immunity of the middle ear: analysis at the single cell level

OBJECTIVE

Studies have suggested that the middle ear is a potential site of immunological regulation and that the middle ear mucosa constitutes a part of the mucosal immune system. We clarify the characteristics of the middle ear mucosa with respect to immune potential.

STUDY DESIGN

We investigated lymphocyte subsets, mRNA of cytokines, and induction of antigen-specific IgA-producing cells in the middle ear mucosa in specific pathogen-free C57BL/6 mice.

RESULTS

Flow cytometric analysis showed a certain amount (10%-15%) of gammadelta T cells among CD3+ T cells. P6-specific IgA-producing cells were induced by intranasal immunization with P6 together with cholera toxin. RT-PCR assay of mucosal T cells detected mRNA of Th2 type cytokines such as IL-5 and IL-10.

CONCLUSION

These findings support the fact that the middle ear is potentially an effector site of the mucosal immunity.

Dietary nucleotides increase the proportion of a TCR gammadelta+ subset of intraepithelial lymphocytes (IEL) and IL-7 production by intestinal epithelial cells (IEC); implications for modification of cellular and molecular cross-talk between IEL and IEC by dietary nucleotides

We have investigated the effects of dietary nucleotides on intraepithelial lymphocytes (IEL) and intestinal epithelial cells (IEC) in weanling mice. The proportion of T-cell receptor (TCR) gammadelta+ IEL in BALB/c mice fed a diet supplemented with nucleotides (NT(+) diet) was significantly higher than that in mice fed the nucleotide-free diet, while the proportion of TCR alphabeta+ IEL in NT(+) diet-fed mice was significantly decreased. The change of the TCR alphabeta+/TCR gammadelta+ ratio was mainly observed in a CD8 alphaalpha+ subset of IEL. IEC from NT(+) diet-fed mice produced a higher level of IL-7, which is important in the development of TCR gammadelta+ IEL, than those from control diet-fed mice. The expression levels of IL-7 and IL-2 receptors on IEL were not different between the two dietary groups. Our findings suggest that the increased population of a TCR gammadelta+ IEL subset by feeding nucleotides may be caused by the increased production of IL-7 by IEC.