海藻希瓦菌对小鼠结直肠腺瘤发生发展及其免疫微环境的影响

Effect of Shewanella algae on the incidence and progression of colorectal adenoma and immune microenvironment in mice

目的 明确海藻希瓦菌(S.algae)对小鼠结直肠腺瘤发生发展的影响及探讨其对免疫微环境的调控作用。方法 将24只小鼠分为3组:对照组、偶氮甲烷(AOM)/葡聚糖硫酸钠(DSS)组、AOM/DSS+S.algae组。比较各组小鼠的生存状态和结直肠腺瘤情况。取AOM/DSS组、AOM/DSS+S.algae组小鼠结直肠组织进行转录组测序,利用基因集富集分析和免疫浸润分析其免疫相关通路、免疫细胞和免疫因子的变化。结果 与AOM/DSS组相比,AOM/DSS+S.algae组小鼠体质量、存活率均下降,血便情况加重,生存状态较差、结直肠长度缩短(P均<0.05),平均腺瘤数量及大小增多(P均<0.05)。与AOM/DSS组相比,AOM/DSS+S.algae组炎症反应增强(P <0.05),促炎细胞因子白介素(IL)-2、IL-6、IL-12、IL-17、干扰素、肿瘤坏死因子(P均<0.05)和IL-1β的产生呈上升趋势,抑炎细胞因子IL-4、IL-10、IL-13(P均<0.05)和转化生长因子β呈抑制趋势,初始B细胞和效应B细胞(P <0.05)呈增多趋势,且激活小鼠体内核因子-κB(NF-κB)信号通路。结论 S.algae可能通过激活免疫信号(如活化B细胞和激活NF-κB通路),形成促肿瘤免疫微环境,进而促进结直肠腺瘤发展。

Objective To investigate the effect of Shewanella algae(S.algae)on the occurrence and development of colorectal adenoma and its regulatory effect on the immune microenvironment in mice.Methods Twenty-four mice were divided into three groups:control group,azoxymethane(AOM)/dextran sodium sulfate(DSS)group,AOM/DSS+S.algae group.The survival status and colorectal adenoma of mice were compared among three groups.Colorectal tissues in the AOM/DSS group and AOM/DSS+S.algae group were collected for high-throughput RNA-seq.Gene set enrichment analysis(GSEA)and cell-type identification by estimating relative subsets of RNA transcripts(CIBERSORT)were used to analyze the changes of immune-related pathways,immune cells and immune factors.Results Compared with the AOM/DSS group,the body weight(P<0.05)and survival rate were decreased,the hematochezia was aggravated,the survival status was worsened,the colorectal length was shortened(all P<0.05),and the average number and size of adenomas were significantly increased(both P<0.05)in the AOM/DSS+S.algae group.Compared with the AOM/DSS group,the inflammatory responses were significantly enhanced in AOM/DSS+S.algae group(P<0.05).The production of pro-inflammatory cytokines including interleukin(IL)-2,IL-6,IL-12,IL-17,interferon(IFN),tumor necrosis factor(TNF)(all P<0.05)and IL-1βshowed an upward trend in the AOM/DSS+S.algae group,while the production of anti-inflammatory cytokines including IL-4,IL-10,IL-13(all P<0.05)and transforming growth factorβshowed an inhibitory trend.Both naive B cells and plasma cells(both P<0.05)were increased in AOM/DSS+S.algae group,and the nuclear factor-κB(NF-κB)signaling pathway was activated.Conclusion S.algae may form a tumor-promoting immune microenvironment by activating immune signals,such as activation of B cells and activation of the NF-κB pathway,and then promote the development of colorectal adenoma.