Causes of inflammatory bowel disease
Last reviewed: 23.04.2024
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The causes of inflammatory bowel disease are not fully understood. According to modern ideas, inflammatory bowel diseases are multifactorial diseases, in the pathogenesis, the influence of genetic predisposition, immunoregulation disorders and autoimmune component is possible. At the heart of the pathology are the damages of the immune mechanisms, but the antigens provoking these changes are not identified. The role of such agents can be claimed by bacterial antigens and their toxins, autoantigens. Secondary effector mechanisms lead to a perversion of the body's immune response to antigenic stimulation and the development of nonspecific immune inflammation in the wall or mucosa of the gut.
An important role is played by genetically caused increased permeability of the intestinal wall, leading to a decrease in the function of the intestinal barrier for bacteria and toxins.
The violation of the immune response is expressed in the selective activation of various subpopulations of T-lymphocytes and changes in macrophage functions, which leads to the release of inflammatory mediators (eicosanoids, platelet activation factors, histamine, kinins, cytokines, active forms of oxygen) and tissue destruction. This is also facilitated by the formation of immune complexes fixed in the lesion. Damage to the epithelium caused by these factors is accompanied by the formation of new antigens of epithelial origin. Migration from the vascular bed to the lesion focus of mononuclear cells and neutrophils increases inflammatory infiltration of the mucosa and leads to the release of new portions of inflammatory mediators. The persistence of antigens and the emergence of new ones closes the "vicious circle".
A genetic predisposition to nonspecific ulcerative colitis has been established. The pathogenesis is based on the inadequacy of immune regulation with autoaggression, the inflammatory reaction of the body. The main symptom of nonspecific ulcerative colitis is blood and mucus in the stool. Depending on the severity of the disease, the stool frequency varies from 3 to 8 times a day. There may be tenesmus, abdominal pain associated with defecation. Body temperature is usually normal, sometimes subfebrile, there may be weakness, weight loss. In blood tests, anemia is usually found, there may be leukocytosis, an increase in ESR is characteristic. In the biochemical analysis of blood - dysproteinemia with a decrease in albumins and an increase in a 2 - and y-globulins, an increase in the level of sialic acids. Diagnosis verifies endoscopic and histological data.
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