Radioactive esophagitis is one of the most common complications in thoracic tumor radiotherapy,biological factors such as single nucleotide polymorphisms (SNPs),miRNAs,and HIV infection may play key roles in the occurrence and development of radioactive esophagitis,and they have become an active field in protection areas of radiotherapy.We can identify the patients who may cause radioactive esophageal in high dose radiotherapy as early as possible,and modify the treatment plan to protect the esophagus.Therefore the biological factors of radioactive esophagitis are of important clinical significance.

Objective:To establish an in vivo model of acute radiation esophagitis in Wistar rats based on a small animal precision radiotherapy platform (SARRP). Methods:Thirty-six Wistar rats were randomly divided into control group, 40, 60 and 75 Gy groups. Based on MRI images, the esophageal target area of rats was outlined and the radiotherapy plan was formulated. The rats were respectively irradiated with 0, 8, 12 and 15 Gy per day for 5 consecutive days. The changes of body weight, food intake, esophageal pathology and magnetic resonance imaging were observed.Results:The body weight of rats in 75 Gy group decreased significantly on the 6th day after irradiation (IR) ( P<0.05). The esophageal tissue of rats in each IR group was thicker than that in control ( F = 14.20, P < 0.05). HE staining showed that the formation rate of radiation-induced esophagitis in 40 Gy and 60 Gy groups were 4/5 and 5/5, respectively, mainly mild. In 75 Gy group, the incidence of radiation-induced esophagitis approached to 5/5, of which 3/5 was severe at 9 d post-IR. The pathological injury scores [ M( Q1, Q3)] of rats in each group were 0, 1.0 (0.5, 2.5), 1.0 (1.0, 2.5) and 4.0 (1.5, 6.0) on the 9th day after IR. There was significant difference between the 75 Gy group and the control group ( H=12.69, P<0.05). After dynamic monitoring of neck MRI images, it was found that the esophageal signal of rats in each IR group increased and widened at 9 d post-irradiation. Conclusions:The animal model of acute radiation-induced esophagitis in rats was successfully established based on a small animal precision radiotherapy platform combined with MRI. 75 Gy was the best irradiation dose and the 9th day was the best observation time point.

Radiotherapy is one of the important cancer therapy methods that can lead to tissue damage including radiation lung injury,radiation esophageal injury,radiation skin damage and abnormal changes in hemopoietic system and immune system.Epigallocatechin-3-gallate (EGCG) is the most abundant catechin in green tea.It has been demonstrated that EGCG has biological effects of antiinflammatory,antioxidant,anti-apoptosis and regulating immunity.Recently some studies of cell and animal models suggest that EGCG has radioprotective effect,but few clinical research was reported.In this review,the studies about EGCG in preventing and treating radiation injury were summarized from antiradiation mechanism in order to enhance the understanding of the potential clinical application of EGCG.

Objective: To analyze the effect of epigallocatechin-3-gallate (EGCG) in radiation induced esophagitis of model rabbit. Methods: Thirty male New Zealand rabbits were randomly divided into EGCG group, saline group, blank group. The rabbits in EGCG and saline groups were irradiated with 6 MV X-rays. The blank group did not receive radiation. After irradiation, rabbits were given with 440 μmol/L EGCG or saline three times a day in continuous 5 days. The scores of pathological changes of esophagus were observed by optical microscope.The serum levels of interleukine-1 beta (IL-1β), interleukine-6 (IL-6), transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α) were detected by enzyme linked immunosorbent assay. The expression levels of 67KD laminin receptor (67LR) was detected by immunohistochemistry. Results: After treatment, the scores of pathological changes of esophagus in blank group, saline group, EGCG group were 0, 3.9±1.10 and 2.80±0.92, respectively. At different time points after drug treatment, the levels of serum inflammatory factors among three groups were significantly different (F=23.66-236.32, P<0.05). The expressions of 67LR in esophageal tissue of 3 groups were also significantly different (F=585.38, P<0.05). Conclusions EGCG reduced radiation-induced esophagitis in rabbits by decreasing the levels of serum inflammatory factors, which may be related to the expression of 67LR protein.