Eosinophilic gastroenteritis: a problem of the mucosal immune system?

The gastrointestinal immune system is a major component of the mucosal barrier, which provides an appropriate immunologic homeostasis between host and numerous foreign antigens, including microbial and dietary antigens. However, under certain pathological circumstances created by disturbance of the immunologic balance, allergic responses associated with the gastrointestinal tract can be triggered by abnormal immune responses against selected food protein antigens. Among the several types of immune competent cells, eosinophils are generally considered to play a central role for the development of allergic diseases in gastrointestinal tissue. Although most research has been focused on the molecular and cellular understanding of eosinophils in the peripheral tissues and lung, recent studies elucidate the unique trafficking and regulation mechanisms of eosinophils in the gastrointestinal tissues. In this review, we summarize current findings in the regulatory mechanism of gastrointestinal eosinophils. Furthermore, several unique murine models for eosinophilic gastroenteritis, which can be applied for the elucidation of underlying mechanisms of eosinophil-mediated gastrointestinal allergy, and the development of new mucosal immune therapy for the control of food allergy are reviewed.