Innate and adaptive immunity in inflammatory bowel disease

• Published in: Autoimmunity reviews Vol. 13; no. 1; pp. 3 - 10
• Main Authors: Geremia, Alessandra, Biancheri, Paolo, Allan, Philip, Corazza, Gino R, Di Sabatino, Antonio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-01-2014
• Subjects: Adaptive Immunity; Allergy and Immunology; Autophagy; Cytokines; Genetic Predisposition to Disease; Humans; Immune System - immunology; Immune System - pathology; Immunity, Innate; Inflammatory Bowel Diseases - genetics; Inflammatory Bowel Diseases - immunology; Innate lymphoid cell; T cell; T-Lymphocytes, Helper-Inducer - immunology; T-Lymphocytes, Helper-Inducer - pathology; ILC; pathogen associated molecular pattern; GWAS; IBD; MyD88; TNF; Autophagy; UC; IFN; myeloid differentiation primary response gene 88; nucleotide-binding oligomerization domain; PRR; natural killer; Th; NLR; ulcerative colitis; TLR; interleukin; iNKT; Toll-like receptor; innate lymphoid cell; CD; NOD-like receptor; NOD; IL; Cytokines; T cell; Treg; Crohn's disease; regulatory T cell; interferon; inflammatory bowel disease; nuclear factor; invariant natural killer T; PAMP; T helper cell type; tumor necrosis factor; NF; genome-wide association studies; NK; dendritic cell; pattern recognition receptor; DC; Innate lymphoid cell
• ISSN: 1568-9972; 1568-9972; 1873-0183
• DOI: 10.1016/j.autrev.2013.06.004

Abstract Inflammatory bowel disease (IBD) includes Crohn's disease (CD) and ulcerative colitis (UC). The exact cause of IBD remains unknown. Available evidence suggests that an abnormal immune response against the microorganisms of the intestinal flora is responsible for the disease in genetically susceptible individuals. The adaptive immune response has classically been considered to play a major role in the pathogenesis of IBD. However, recent advances in immunology and genetics have clarified that the innate immune response is equally as important in inducing gut inflammation in these patients. In particular, an altered epithelial barrier function contributes to intestinal inflammation in patients with UC, while aberrant innate immune responses, such as antimicrobial peptide production, innate microbial sensing and autophagy are particularly associated to CD pathogenesis. On the other hand, besides T helper cell type (Th)1 and Th2 immune responses, other subsets of T cells, namely Th17 and regulatory T (Treg) cells, are likely to play a role in IBD. However, given the complexity and probably the redundancy of pathways leading to IBD lesions, and the fact that Th17 cells may also have protective functions, neutralization of IL-17A failed to induce any improvement in CD. Studying the interactions between various constituents of the innate and adaptive immune systems will certainly open new horizons in the knowledge about the immunologic mechanisms implicated in gut inflammation.