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Causes of inflammatory bowel disease
Last reviewed: 06.07.2025
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The causes of inflammatory bowel diseases have not been fully studied. According to modern concepts, inflammatory bowel diseases are multifactorial diseases, the pathogenesis may be influenced by genetic predisposition, immune regulation disorders and an autoimmune component. The pathology is based on damage to immune mechanisms, but the antigens that provoke these changes have not been identified. Bacterial antigens and their toxins, autoantigens may claim the role of such agents. Secondary effector mechanisms lead to a distortion of the body's immune response to antigen stimulation and the development of nonspecific immune inflammation in the wall or mucous membrane of the intestine.
A significant role is played by genetically determined increased permeability of the intestinal wall, leading to a decrease in the function of the intestinal barrier for bacteria and toxins.
The immune response disorder is expressed in the selective activation of various T-lymphocyte subpopulations and changes in macrophage functions, which leads to the release of inflammation mediators (eicosanoids, platelet activating 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 the listed factors is accompanied by the formation of new antigens of epithelial origin. Migration of mononuclear cells and neutrophils from the vascular bed to the lesion site enhances the inflammatory infiltration of the mucous membrane and leads to the release of new portions of inflammation mediators. The persistence of previous antigens and the appearance of new ones closes the "vicious circle".
Genetic predisposition to nonspecific ulcerative colitis has been established. The pathogenesis is based on immune regulation deficiency with autoaggression, and disorders of the body's inflammatory response. The main symptom of nonspecific ulcerative colitis is blood and mucus in the stool. Depending on the severity of the disease, the frequency of stool 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. Blood tests usually reveal anemia, there may be leukocytosis, and an increase in ESR is typical. In the biochemical blood test, there is dysproteinemia with a decrease in albumins and an increase in a 2 - and y-globulins, an increase in the level of sialic acids. The diagnosis is verified by endoscopic and histological data.
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