The effect of amifostine on bacterial translocation after radiation ınduced acute enteritis

Pathogenesis and therapy of radiation enteritis with gut microbiota

Radiotherapy is widely used in clinic due to its good effect for cancer treatment. But radiotherapy of malignant tumors in the abdomen and pelvis is easy to cause radiation enteritis complications. Gastrointestinal tract contains numerous microbes, most of which are mutualistic relationship with the host. Abdominal radiation results in gut microbiota dysbiosis. Microbial therapy can directly target gut microbiota to reverse microbiota dysbiosis, hence relieving intestinal inflammation. In this review, we mainly summarized pathogenesis and novel therapy of the radiation-induced intestinal injury with gut microbiota dysbiosis and envision the opportunities and challenges of radiation enteritis therapy.

Intestinal mucositis precedes dysbiosis in a mouse model for pelvic irradiation

Pelvic radiotherapy is known to evoke intestinal mucositis and dysbiosis. Currently, there are no effective therapies available to mitigate these injuries, which is partly due to a lack of insight into the events causing mucositis and dysbiosis. Here, the complex interplay between the murine host and its microbiome following pelvic irradiation was mapped by characterizing intestinal mucositis along with extensive 16S microbial profiling. We demonstrated important morphological and inflammatory implications within one day after exposure, thereby impairing intestinal functionality and inducing translocation of intraluminal bacteria into mesenteric lymph nodes as innovatively quantified by flow cytometry. Concurrent 16S microbial profiling revealed a delayed impact of pelvic irradiation on beta diversity. Analysis of composition of microbiomes identified biomarkers for pelvic irradiation. Among them, members of the families Ruminococcaceae, Lachnospiraceae and Porphyromonadaceae were differentially affected. Altogether, our unprecedented findings showed how pelvic irradiation evoked structural and functional changes in the intestine, which secondarily resulted in a microbiome shift. Therefore, the presented in vivo irradiation-gut-microbiome platform allows further research into the pathobiology of pelvic irradiation-induced intestinal mucositis and resultant dysbiosis, as well as the exploration of mitigating treatments including drugs and food supplements.

Gut microbiota response to ionizing radiation and its modulation by HDAC inhibitor TSA

AIM

Trichostatin A (TSA) has been shown to mitigate whole body γ-radiation-induced morbidity and mortality. The current study aimed at studying the effects of TSA post-irradiation treatment on gut-microbiota, especially the translocation of the microbes from the intestine to other organs in C57 Bl/6 mice model.

MATERIALS AND METHODS

On 1st, 3rd 5th 7th 9th 12th and 14th days after various treatments bacteria were isolated from the intestine and nearby organs (mesenteric lymph node, spleen and liver) for further analysis. The jejunum part of all animals was processed for histological analysis.

RESULTS

The group radiation + drug showed reduced susceptibility to radiation injury as well as microbiota related anomalies compared to the irradiated alone group. This was described by increased microflora in different parts of the GI tract in the radiation + drug group compared to the irradiated group and reduced histopathological damages in the jejunum. Also, a reduced percentage of translocated bacteria were found in different organs of radiation + drug group animals.

CONCLUSION

TSA treatment post-irradiation could effectively control bacterial translocation as well as GI injury in mice.

Radiofrequency ablation in a patient with radiation enteritis: A case report

RATIONALE

Radiation enteritis (RE) is one of the serious complications caused by the radiotherapy and it can occur in any segment of the intestine, including small intestine, colon, and rectum. It can cause a number of serious problems of the intestine, such as chronic ulcers, bleeding, intestinal stenosis, intestinal fistula, and perforation. At present, there is no standard treatment guideline for the RE.

PATIENT CONCERNS

A 54-year-old male patient received surgery and chemotherapy for rectal cancer and radiofrequency ablation (RFA) for a single metastatic carcinoma of the liver. Three years later, he was diagnosed with recurrent lesion in the rectal anastomotic stoma and was treated with radiotherapy with a total dose of 70 Gy. Following this, he had persistent abdominal pain and diarrhea for 1 year.

DIAGNOSES

Colonoscopy confirmed a diagnosis of RE.

INTERVENTIONS

Since intestinal probiotics, intestinal mucosal protectants, antidiarrheal drugs, and other treatments were not effective; the patient was treated by RFA.

OUTCOMES

Clinical symptoms of the patient were gradually decreased after the RFA. Colonoscopy examination was performed 3 months later and intestinal mucosa was found to have healed well.

LESSONS

RFA is an effective treatment for patients with RE, and it is expected to be one of the standard treatments for the RE.

Beta-Hydroxy-Beta-Methyl-Butyrate, L-glutamine, and L-arginine Supplementation Improves Radiation-Induce Acute Intestinal Toxicity

We aimed to evaluate effects of β-hydroxy-β-methylbutyrate, L-glutamine, and L-arginine (HMB/GLN/ARG) on radiation-induced acute intestinal toxicity. Forty rats were divided into four groups: group (G) 1 was defined as control group, and G2 was radiation therapy (RT) control group. G3 and G4 were HMB/GLN/ARG control and RT plus HMB/GLN/ARG groups, respectively. HMB/GLN/ARG started from day of RT and continued until the animals were sacrificed 10 days after RT. The extent of surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis, crypt distortion, regenerative atypia, vascular dilatation and congestion, and fibrosis were quantified on histological sections of intestinal mucosa. Statistical analyses were performed using the analysis of variance (ANOVA) test. There were significant differences between study groups regarding extent of surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis and crypt distortion, regenerative atypia, vascular dilatation and congestion, and fibrosis (p values were 0.019 for fibrosis, <.001 for the others). Pair-wise comparisons revealed significant differences regarding surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis, vascular dilatation, and congestion between G2 and G4 (p values were <.001, .033, <.001, .007, and <.001, respectively). Fibrosis score was significantly different only between G1 and G2 (p = .015). Immunohistochemical TGF-β score of G2 was significantly higher than G1 and G3 (p values were .006 and .017, respectively). There was no difference between TGF-β staining scores of G2 and G4. Concomitant use of HMB/GLN/ARG appears to ameliorate radiation-induced acute intestinal toxicity; however, this finding should be clarified with further studies.

Rebamipide alleviates radiation-induced colitis through improvement of goblet cell differentiation in mice

BACKGROUND AND AIM

Radiation-induced colitis is a common clinical problem associated with radiotherapy and accidental exposure to ionizing radiation. Goblet cells play a pivotal role in the intestinal barrier against pathogenic bacteria. Rebamipide, an anti-gastric ulcer drug, has the effects to promote goblet cell proliferation. The aim of this study was to investigate whether radiation-induced colonic injury could be alleviated by rebamipide.

METHODS

This study orally administered rebamipide for 6 days to mice, which were subjected to 13 Gy abdominal irradiation, to evaluate the therapeutic effects of rebamipide against radiation-induced colitis. To confirm the effects of rebamipide on irradiated colonic epithelial cells, this study used the HT29 cell line.

RESULTS

Rebamipide clearly alleviated the acute radiation-induced colitis, as reflected by the histopathological data, and significantly increased the number of goblet cells. The drug also inhibited intestinal inflammation and protected from bacterial translocation during acute radiation-induced colitis. Furthermore, rebamipide significantly increased mucin 2 expression in both the irradiated mouse colon and human colonic epithelial cells. Additionally, rebamipide accelerated not only the recovery of defective tight junctions but also the differentiation of impaired goblet cells in an irradiated colonic epithelium, which indicates that rebamipide has beneficial effects on the colon.

CONCLUSIONS

Rebamipide is a therapeutic candidate for radiation-induced colitis, owing to its ability to inhibit inflammation and protect the colonic epithelial barrier.