Gut mucosa is the major site of contact with antigens. In addition, it lodges the largest lymphoid tissue in the body. In physiological conditions, microbiota and dietary antigens are the natural sources of stimulation for the gut-associated lymphoid tissue (GALT) and for the immune system. Most of GALT cells are activated and a variety of proinflammatory mediators are found in this site. Local regulatory elements, however, act as a robust network that keeps gut homeostasis at check. Usually, antigen ingestion induces two noninflammatory immune responses, oral tolerance, and production of secretory IgA. However, under pathological circumstances, mucosal homeostasis is disturbed resulting in inflammatory conditions such as food hypersensitivity and inflammatory bowel diseases (IBD). The number of reported cases of food allergy and chronic IBD such as ulcerative colitis and Crohn's disease grew enormously in the past decade. Although therapies for these diseases have improved, they are still only modestly successful for long-term use and they all have many side effects. The aim of this special issue will be to shed some light into the mechanisms that keep intestinal homeostasis and to alternative therapeutic approaches for pathological conditions that emerge when theses mechanisms fail.

We invite authors to present original research articles as well as review articles that will contribute to the debate. Potential topics include, but are not limited to:

• Oral tolerance, its mechanisms and applications
• Role of microbiota or/and dietary antigens in the immune function
• Cells and mediators that keep the gut homeostasis (such as induced regulatory T cells, TLRs, lipid mediators, subsets of intra-epithelial lymphocytes, and B and T cells)
• Role of inflammatory and regulatory cytokine networks in the gut (such as TGF-β, IL-10, IL-17, IL-21, IL-22, and IL-25)
• Role of probiotics in gut homeostasis and disease treatment
• Food allergy
• Coeliac disease
• Inflammatory bowel diseases (ulcerative colitis and Crohn's disease)
• Infections initiated at the gut mucosa (including HIV, other viruses, and bacterial and parasitic infections)
• Intestinal cancer
• Animal models of gut inflammatory diseases
• Therapeutic alternatives for gut inflammatory diseases

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/jir/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: