Evidences have shown that dysbiosis could promote the progression of colorectal cancer (CRC). However, the association of dysbiosis and prognosis of CRC is barely investigated. Therefore, we used 16S rRNA gene sequencing approach to determine differences in microbiota among tumor tissues of different prognosis and found that Fusobacterium nucleatum and Bacteroides fragilis were more abundant in worse prognosis groups, while Faecalibacterium prausnitzii displayed higher abundance in survival group. To further explore the prognostic value of the found bacteria, Kaplan–Meier and Cox proportional regression analyses were used and the results exhibited that high abundance of F. nucleatum and B. fragilis were independent indicators of poor patient's survival. Besides, the expression of major inflammatory mediator were analyzed using PCR and western blot methods, and it turned out that high abundance of F. nucleatum was associated with increased expression of TNF-α, β-catenin and NF-κB, while COX-2, MMP-9 and NF-κB were positively related with high B. fragilis level, and high level of F. prausnitzii showed lower expression of β-catenin, MMP-9 and NF-κB. Moreover, immunohistochemical analysis indicated that KRAS and BRAF expression were prominent in F. nucleatum and B. fragilis high abundance group, while MLH1 showed lower expression. In conclusion, F. nucleatum, B. fragilis and F. prausnitzii can be identified as useful prognostic biomarkers for CRC, and dysbiosis might worsen the patients' prognosis by up-regulating gut inflammation level.

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Evidence has shown that neoadjuvant chemotherapy (NACT) is correlated with patients’ overall postoperative complications. But investigations on relationship between NACT and postoperative infectious complications, which is closely linked to intestinal barrier damage, were scanty. Accordingly, 90 patients with advanced gastric cancer were included in this study. The differences in postoperative infectious complications were determined between NACT group in which patients received NACT before surgery and SURG group in which received surgical treatment immediately after diagnosis. The damage of mechanical structure of intestinal barrier was assessed by hematoxylin and eosin staining, transmission electron microscopy, and immunohistochemistry. Mucosal microbiota changes were determined by using a 16S rRNA gene sequencing approach. Results showed that the incidence of postoperative infectious complications were significantly higher in the NACT group. Tight junctions were disrupted, and claudin-1, ZO-1 and occludin were down-regulated in patients with infectious complications in overall compared with those without. And similarly, the patients in the NACT group also showed damaged intestinal barrier compared with those in SURG group. Besides, the total diversity of mucosal related bacteria was decreased and relative abundance of some probiotics, such as Bifidobacterium, Faecalibacterium and Ruminococcus, was reduced in the NACT group as well. In conclusion, our study identifies a higher incidence of postoperative infection in gastric cancer patients who underwent NACT treatment, and these changes might be caused by a significant damage in the intestinal barrier as well as reduced probiotics.

The laparoscopic approach for SBO is feasible because of its fewer complications and hospital stay.

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