We investigate the effects of Clostridium butyricum(CB) on gut microbiota and colitis associated colon cancer(CAC) in mice.6–8 weeks old C57BL/6 mice were randomly divided into control, azoxymethane (AOM) + dextran sodium sulphate (DSS) and AOM + DSS + CB groups. Mice in the latter two groups received an intraperitoneal injection of AOM (12.5 mg/kg), followed by three cycles of DSS diluted in water (2.5% w/v). Mice in treatment group received CB (2 × 10⁸ CFU in 200 ul normal saline) by gavage administration three times one week. Microbiota composition was assessed by 16S rRNA high-throughput sequencing. Colon samples were collected to examine severity of colitis and tumorigenesis. Cytokines including TNF-a, IL-6 and Cyclo-oxygenase-2 (COX-2) were detected by RT-qPCR. Expression of Bcl-2, Bax and the state of components of NF-κB signaling pathway were detected by western blot. The results revealed that CB regulated structure of intestinal flora and changed the microbial composition; decreased Firmicutes/ Bacteroidetes ratio in phylum level and increased the relative abundance of probiotics; decreased colitis, decreased incidence and size of colorectal cancer(CRC) and increased apoptosis of tumor cells; decreased cytokines including TNF-a and IL-6; decreased level of COX-2; decreased phosphorylation of NF-κB; decreased level of Bcl-2 and increased expression of Bax. In conclusion, CB could regulate structure and composition of gut microbiota and reduces colitis associated colon cancer in mice, the mechanism may be inhibiting NF-κB pathway and promoting apoptosis.

我们研究了丁酸梭菌（CB）对小鼠肠道菌群和结肠炎相关结肠癌（CAC）的影响。6–8周龄的C57BL / 6小鼠随机分为对照组，乙氧基甲烷（AOM）+葡聚糖硫酸钠（DSS）和AOM + DSS + CB组。后两组的小鼠接受腹膜内注射AOM（12.5 mg / kg），然后进行三个周期的DSS用水稀释（2.5％w / v）。治疗组小鼠接受CB（2×10 ⁸每周三次通过管饲法在200 ul生理盐水中加入CFU。通过16S rRNA高通量测序评估微生物群组成。收集结肠样品以检查结肠炎和肿瘤发生的严重性。通过RT-qPCR检测到包括TNF-α，IL-6和环氧合酶-2（COX-2）在内的细胞因子。Western blot检测Bcl-2，Bax的表达及NF-κB信号通路的成分状态。结果表明，CB调节肠道菌群结构并改变了微生物组成。门生水平的硬毛/拟杆菌比率降低，益生菌的相对丰度增加；结肠炎减少，结直肠癌（CRC）的发生率和大小降低，肿瘤细胞凋亡增加；细胞因子减少，包括TNF-α和IL-6；COX-2水平降低；NF-κB的磷酸化降低；Bcl-2水平降低和Bax表达增加。总之，CB可以调节小鼠肠道菌群的结构和组成，减少结肠炎相关的结肠癌，其机制可能是抑制NF-κB通路并促进细胞凋亡。