Oxidative Stress in the Pathogenesis of Crohn's Disease and the Interconnection with Immunological Response, Microbiota, External Environmental Factors, and Epigenetics.

Inflammatory bowel disease (IBD) is a complex multifactorial disorder in which external and environmental factors have a large influence on its onset and development, especially in genetically susceptible individuals. Crohn's disease (CD), one of the two types of IBD, is characterized by transmural inflammation, which is most frequently located in the region of the terminal ileum. Oxidative stress, caused by an overabundance of reactive oxygen species, is present locally and systemically in patients with CD and appears to be associated with the well-described imbalanced immune response and dysbiosis in the disease. Oxidative stress could also underlie some of the environmental risk factors proposed for CD. Although the exact etiopathology of CD remains unknown, the key role of oxidative stress in the pathogenesis of CD is extensively recognized. Epigenetics can provide a link between environmental factors and genetics, and numerous epigenetic changes associated with certain environmental risk factors, microbiota, and inflammation are reported in CD. Further attention needs to be focused on whether these epigenetic changes also have a primary role in the pathogenesis of CD, along with oxidative stress.