The contribution of radiation-induced injury to the gastrointestinal tract in the development of multi-organ dysfunction syndrome or failure

Severe damage to the gastrointestinal tract (GIT), such as loss of the gastrointestinal mucosa and haemorrhage, following accidental overexposure to ionising radiation appears to be a determinant feature in patient mortality. Injury to the GIT may be direct, as this tissue is particularly radiation sensitive, as well as indirect as a result of radiation burns and bone marrow aplasia. Similar to other severe trauma situations such as thermal burns, radiation exposure results in reduced intestinal barrier integrity, which initiates and/or perpetuates inflammatory–anti-inflammatory mediator release. This may result in damage to distant organs. In this context, the injured gut may be considered as a “key player” or “motor” in the development of multiple organ dysfunction syndrome or failure. Of note is that radiation exposure elicits similar GIT injury of both mucosal and vascular elements, in contrast to other severe physical insults. Common factors are the intestinal inflammatory response and loss of barrier function. However, bone marrow injury must be taken into account in intestinal responses.