Manipulation of Intestinal Flora as a Way to Treat Crohn's Disease: The Role of Probiotics, Prebiotics and Antibiotics

Crohn’s disease (CD) is a chronic gastrointestinal disorder which, together with ulcerative colitis, is known as Inflammatory Bowel Disease (IBD). CD is characterized by transmural inflammation of the entire gastrointestinal tract, from oral cavity to anus. The most common symptoms are chronic diarrhea and abdominal pain, which are often accompanied by anorexia, malaise, weight loss, fever and extra-intestinal manifestations. The latter can involve almost every organ system (Macfarlane et al., 2009). CD can cause the formation of strictures, abscesses or fistulas. For that reason, surgical resection in CD patients is very common. Regardless of the vast amount of data gathered on the etiology and the course of CD, the actual cause is still unknown. The interplay of various factors is blamed for the disease outbreak. These factors include genetic predisposition, environmental influences (e.g. smoking), imbalance in immune response and changes in intestinal flora. Given the complexity of the disease, some factors may be the consequence of others. Genetic predisposition has received the most research attention in recent years. Family studies have shown that more than 50% concordance of CD can be expected in monozygotic twins. These findings indicate that the pathogenesis of CD is not based only on one gene but on a polygenic risk profile (Vavricka & Rogler, 2009). In 2001, two independent groups of researchers discovered one of the most important susceptibility genes for CD, a gene for NOD2/CARD15 (Hugot et al., 2001; Ogura et al., 2001). Its mutation is present in about one third of all CD patients. Patients with mutated NOD2/CARD15 variants could have a deficient response to bacterial LPS which could lead to the development of CD (Ogura et al., 2001). Several other genes that can contribute to susceptibility to CD have been identified. These include IBD5, IL23R, ATG16L1, Chr5p13.1, Chr5q33.1 and Chr10q21.1 (Xavier & Podolsky, 2007). They are involved in the maintenance of barrier function and regulation of innate and adaptive immunity. There are several environmental factors that have been predicted to be involved in the development of CD. The single most important environmental risk factor for the development of CD is tobacco smoking. Further environmental risk factors are related to living in urban areas of developed western countries with stressful lifestyle. There is also some evidence that diet could influence the risk for CD. Uptake of fatty acids and sugar,