The multifaceted influence of the mucosal microflora on mucosal dendritic cell responses

Over the last decade, it has become apparent that the complex interactions between components of the mucosal microflora and the mucosal immune system can involve either direct contact with dendritic cells in the lamina propria or, alternatively, contact with epithelial cells lining the mucosa that then influence the function of dendritic cells. Although in some cases these interactions involve signaling specific to particular organisms and in others, to classes of organisms, a common theme is that signaling is invariably channeled through receptors that address many organisms or all organisms such as the pattern-recognition receptors TLR and NLR. Here, I review this information with the intention of identifying how the mucosal microflora influences specific functions of the mucosal immune system such the production of particular cytokines as well as broader functions such as the maintenance of mucosal immune homeostasis and host defense.