The Microbiome and Radiation Induced-Bowel Injury: Evidence for Potential Mechanistic Role in Disease Pathogenesis

Abstract

Radiotherapy has played a major role in both the curative and palliative treatment of cancer patients for decades. However, its toxic effect to the surrounding normal healthy tissue remains a major drawback. In cases of intra-abdominal and/or pelvic malignancy, healthy bowel is inevitably included in the radiation field, causing undesirable consequences that subsequently manifest as radiation-induced bowel injury, which is associated with significant morbidity and mortality. The pathophysiology of radiation-induced bowel injury is poorly understood, although we now know that it derives from a complex interplay of epithelial injury and alterations in the enteric immune, nervous, and vascular systems in genetically predisposed individuals. Furthermore, evidence supporting a pivotal role for the gut microbiota in the development of radiation-induced bowel injury has been growing. In this review, we aim to appraise our current understanding of radiation-induced bowel injury and the role of the microbiome in its pathogenesis as well as prevention and treatment. Greater understanding of the relationship between the disease mechanism of radiation-induced bowel injury and gut microbiome might shed light on potential future prevention and treatment strategies through the modification of a patient’s gut microbiome.

Guiqi Baizhu Decoction Alleviates Radiation Inflammation in Rats by Modulating the Composition of the Gut Microbiota

“…However, its toxic effect to the surrounding normal healthy tissue remains a major drawback. Evidence has shown that the widespread use of ionizing radiation (IR) can cause high incidence of radiation-induced side effects in up to 75% during the process of radiotherapy [ 2 ]. The most common IR exposure damage effects are bone marrow inhibition and gastrointestinal toxicity [ 3 , 4 ].…”

Changes in the Gut Microbiome Community of nonhuman primate following radiation injury

“…Treatment for almost all types of cancers includes surgery, chemotherapy, and radiation. Ionizing radiation results in the damage of DNA, which ultimately results in cell death [2].…”

“…Although ionizing radiation is highly effective at inducing DNA damage in cancer cells, which leads to cell death, nearby healthy cells are also affected [2]. Localized radiation is possible with most cancers, but for abdominal cancers a broader eld area of ionizing radiation is necessary and can cause serious effects on normal tissue including the gastrointestinal tract.…”

“…In particular, the epithelial cells of the intestines are rapidly dividing healthy cells commonly adversely affected by irradiation. A common side-effect of irradiation is diarrhea, which can negatively affect quality of life as well as radiation injury treatment outcome [2,3]. Intestinal radiation injury is a signi cant clinically unmet challenge.…”

“…Previous studies have shown that ionizing radiation induces signi cant changes in the microbiome [2,7]. More recently, it has been shown that ionizing radiation induced diarrhea may be determined by pre-irradiation microbiome compositions [8][9][10].…”