放疗后肠道炎症与口腔菌群变化：基于直肠癌患者的初步研究

Post-Radiotherapy Intestinal Inflammation and Oral Microbiota Alterations: A Preliminary Study in Rectal Cancer Patients

摘要: 背景：中晚期结直肠癌(CRC)常建议新辅助放疗来达到缩小肿瘤，以便有助于手术，降低肿瘤分期。术前行新辅助放疗势必会造成肠道菌群紊乱，进而引起放射性肠炎，有文献报道CRC患者口腔菌群也会发生相应的变化，现有研究表明，CRC患者的口腔微生物组成与健康人群存在显著差异。本研究旨在分析放疗后不同时间间隔肠黏膜样本中炎症因子的比例，来推测放疗后不同时间患者肠道炎症的严重程度。以及通过高通量测序患者唾液微生物群落中细菌的16sRNA，探究新辅助放疗后结直肠癌患者口腔微生物群的变化。方法：选取本中心21例未接受放疗、放疗后不同时间间隔接受手术治疗的患者的肠黏膜样本和唾液样本。采用酶联免疫吸附法(ELISA)定量检测肠黏膜组织中肿瘤坏死因子-α (TNF-α)、白细胞介素-4 (IL-4)和白细胞介素-6 (IL-6)的表达水平。通过16s rRNA测序检测唾液样品中微生物群落的变化。结果：在接受放疗的个体中，肠道黏膜内的炎性细胞因子浓度升高，同时白细胞介素-4水平呈动态变化。尽管放疗后，各类炎症标志物的浓度会随时间推移逐渐下降，但在放疗后约12周时，其浓度仍高于未接受放疗的患者。微生物组分析结果显示，放疗患者与未接受放疗的患者口腔菌群存在一定的差异，但也存在一定局限性。结论：新辅助放疗结束至手术的这一段时间，虽然放射性肠炎有所恢复，仍高于未接受放疗的患者。同时，患者口腔菌群发生了改变，这为探索肠道疾病的早期诊断指标提供了线索。

Abstract: Background: Neoadjuvant radiotherapy is commonly recommended for locally advanced Colorectal Cancer (CRC) to downstage tumors and facilitate surgical resection. However, preoperative radiotherapy inevitably disrupts the intestinal microbiota and may induce radiation enteritis. Studies have reported corresponding changes in the oral microbiota of CRC patients, with existing evidence indicating significant differences in oral microbial composition between CRC patients and healthy individuals. This study aims to evaluate the severity of intestinal inflammation at different post-radiotherapy intervals by analyzing inflammatory cytokine levels in intestinal mucosal samples, and to explore changes in the oral microbiota of CRC patients following neoadjuvant radiotherapy through high-throughput sequencing of bacterial 16S rRNA in saliva samples. Methods: Intestinal mucosal and saliva samples were collected from 21 patients in our center who either did not receive radiotherapy or underwent surgery at varying intervals after radiotherapy. The expression levels of Tumor Necrosis Factor-alpha (TNF-α), Interleukin-4 (IL-4), and Interleukin-6 (IL-6) in intestinal mucosal tissues were quantitatively measured using Enzyme-Linked Immunosorbent Assay (ELISA). Changes in the salivary microbial community were assessed via 16S rRNA sequencing. Results: In patients who received radiotherapy, the concentrations of inflammatory cytokines in the intestinal mucosa were elevated, with dynamic changes observed in IL-4 levels. Although the levels of these inflammatory markers gradually decreased over time after radiotherapy, they remained higher than those in non-radiotherapy patients even at approximately 12 weeks post-radiotherapy. Microbiome analysis revealed certain differences in oral microbiota composition between radiotherapy and non-radiotherapy patients, although some limitations were noted. Conclusion: During the interval between the completion of neoadjuvant radiotherapy and surgery, although radiation enteritis shows some recovery, the inflammatory status remains higher than that in patients who did not receive radiotherapy. Additionally, differences in the oral microbiota were observed, providing clues for the exploration of early diagnostic markers for intestinal diseases.