Intestinal mucosa forms a strong interface between the body tissues and external environment, by forming a well-structured barrier against physical, chemical stress and microorganisms. In fact, the epithelial layer, mucus, antimicrobial peptides, secreted immunoglobulin A, and innate and adaptive immune cells together form efficient and complex mucosal barrier. All these components help to establish a beneficial “ecosystem” where a diverse and dense commensal community is tolerated, without immune attack for the benefit of the host. Damage of this mutualistic relationship can result in severe inflammatory ulcerative colitis and other metabolic syndromes. On the other hand, the contribution of gut immune cells, such as dendritic cells (DCs), in regulating the mucosal barrier, epithelial integrity, production of bactericidal enzymes, or antimicrobial peptides, is poorly understood.