结肠炎是什么原因造成的
最佳答案：
Etiology
Ulcerative colitis is characterized as an idiopathic disease,however various possible etiologies have been proposed. The major hypotheses regarding the etiology of UC have included infection,allergy to dietary components,immune responses to bacterial or self-antigens and environmental causes. Infectious causes include pathogenic microbial antigenic triggers that have yet to be identified. However,it appears to be more likely that normal intestinal microflora as opposed to pathogenic organisms may have a significant role in development of IBD (Stevenson and Korzenik 2003). Defective colonic mucosa and abnormal intestinal epithelial permeability may increase the access of luminal dietary and bacterial products to the mucosa ). Environmental causes have been proposed in relationship to the prevalence of IBD ). However,there has been little evidence that any particular food components play a primary role in the etiology of the disease. Fecal stream has been shown to be a factor in promoting further mucosal inflammation and therefore the importance of the role of gut flora in IBD has been brought forward. While smoking has been related to increased risk for activity of disease in Crohn’s disease,it has demonstrated a protective effect in UC with the highest risk of developing UC in the first 2 years after cessation of smoking (Stevenson and Korzenik 2003).
Genetic studies have suggested that first-degree relatives have increased absolute risk of 7 percent,which is 4 to 20 times as higher than compared to the normal population ). However,there is a low concordance rate in monozygotic twins,indicating that environmental factors are also involved ). Genetic linkage studies suggest an association between ulcerative colitis and the human leukocyte antigen (HLA) genes on chromosomes 12 and 16,but specific responsible genes are not well defined (Stevenson and Korzenik 2003). Genetic alteration experiments performed in germ-free environments have not yielded colitis,thus supporting the theory of a multifactorial cause of UC (Boden and Cho 2003).","department":"
