Interaction between the microbiome and the severity of diversion colitis after low anterior resection of rectal cancer
Authors: Sun Qiang , Shi Yunjie , Liang Xiaoben , Lu Hao , Huang Yu , Zhu Lin , Wang Wenqiang , Zhang Wei , Hu Zhiqian , Li Xinxing 
Published: June 2022

Background
Diversion colitis (DC) DC is nonspecific inflammation of the distal intestinal mucosa following disruption of colonic continuity with colonic dysfunction. With the gradual prolongation time of the ileostomy status, the condition of DC may become increasingly severe. However, the corresponding pathogenesis of DC has not been clarified yet.
Methods
(1)Retrospective study: Clinical information were collected from patients with low rectal cancer admitted to the Department of Anorectal Surgery, Changzheng Hospital, from April 2017 to April 2019. These patients underwent laparoscopic low anterior resection (LAR) combined with terminal ileum enterostomy (dual-chamber). We used chi-square test to comparethe clinical baseline information, clinical symptoms, and endoscopic characteristics between different severity of DC; (2)Prospective nested case-control study: We recruited 40 patients with laparoscopic anterior low resection combined with terminal ileum enterostomy and they were further classified into mild group and severe group according to the scores of endoscopic examinations for DC. The following indexes were tested in the above two groups to verify histological differences between different severity of DC: Calprotectin in intestinal lavage fluid, inflammatory factors in tissue and plasma, and Lipopolysaccharide levels in plasma. Moreover, 16s-rDNA sequencing was carried out to analyze the diversity and and differences of microbiome in the intestinal lavage fluid of the two groups.
Results
(1)Retrospective study: According to the endoscopic scores, the retrospective clinical data were divided into 52 cases in the mild group and 58 cases in the severe group. We found that age, BMI, history of diabetes, and symptoms associated with the state of the stoma were the independent risk factors that affect DC severity (P༜0.05). Meanwhile, age, BMI, history of diabetes and endoscopic score were found to be independent risk factors affecting the severity of diarrhea after enterostomy(P༜0.05), which was consistent with our results of differentiating the severity of DC under endoscopy; (2)Prospective nested case-control study:40 patients with low rectal cancer recruited by sample size calculation, 23 were in the mild group and 17 in the severe group. In particular, Calprotectin in the intestinal lavage fluid, TNF-α, IL-1β, IL-6 and IL-17 in tissue/plasma, and Lipopolysaccharide in plasma of severe group were significantly higher than that of mild group (P༜0.05). The results of 16s-rDNA sequencing showed thatmicromicrobiome with high enrichment values primarily consisted of Bifidobacteriales and Prevotella in mild group, whereas that in the severe group consisted of Providencia and Dorea. The functional predictions on such two types of microbiome were mainly focused on lipid synthesis, glycan synthesis, metabolism, and amino acid metabolism pathways.
Conclusion
After enterostomy closure surgery, a series of severe clinical symptoms might appear in DC patients. There were significant differences in local and systemic inflammatory responses, composition of gut microbiota between DC patients with different endoscopic scores, which provide a basis for the clinical interventional treatment for enterostomy status-related DC in patients with permanent stoma.