结直肠癌（CRC）是常见消化道恶性肿瘤，尚无可靠防控方法。研究表明，CRC患者脂质代谢异常，肠道菌群紊乱；特定肠道益生菌Akkermansia muciniphila（Akk）及外膜蛋白影响机体脂质代谢及恶性肿瘤免疫疗效。课题组预实验发现，Akk菌/外膜蛋白能改变巨噬细胞表型，抑制CRC形成，但机制不清。因此猜想：Akk/外膜蛋白可通过扰动脂质代谢影响M2巨噬细胞极化及功能，并反向调控肠道菌群和免疫代谢，抑制CRC发生发展。本研究结合荧光标记单抗流式细胞术（FCM）及荧光激活细胞分选与气相/超高效液相色谱-高分辨串联质谱（FACS-GC/UPLC-MS/MS）联用构建Akk菌高效检测和巨噬细胞分选-代谢组学新方法；探明Akk菌/外膜蛋白干预免疫细胞亚群及脂质代谢效应和CRC模型动物肠道菌群及免疫代谢变化，并开展临床样本验证。该研究从卫生分析化学角度为CRC免疫代谢防控提供新原理和新技术。

Colorectal cancer (CRC) is a common malignant tumour in digestive tract, and there is no reliable method for its prevention and control. Studies have shown that there are abnormal lipid metabolism and disordered intestinal flora in CRC patients, and a pecific intestinal bacteria probiotic Akkermansia muciniphila (Akk) and its outer membrane protein may affect lipid metabolism and immunotherapy response of malignant tumors. The results of our preliminary experiment have shown that Akk bacteria/outer membrane protein can change macrophage phenotype and inhibit CRC formation, but the mechanism is unclear. Therefore, it is speculated that Akk bacteria/outer membrane protein can affect M2 macrophages polarization and function by disturbing its lipid metabolism, and reverse regulate intestinal flora and immune metabolism to inhibit the development of CRC. In this study, a new method for efficient detection of Akk bacteria and analysis of macrophage metabolism was established by combining fluorescent labeled monoclonal antibody flow cytometry (FCM) and fluorescent activated cell sorting (FACS) with gas chromatography/ultra-high performance liquid chromatography- high resolution tandem mass spectrometry (GC/UPLC-MS/MS). The CRC mouse model induced by azoxymethane (AOM)/dextran sodium sulfate (DSS) is employed to explore the effects of Akk bacteria/outer membrane protein on immune cell subsets and its lipid metabolism by FACS-GC/UPLC-MS/MS excepting gut microbiota based 16S rRNA. People with colorectal cancer will be recruited in affiliated hospital under the guidance of ethical permission and informed consent, and the clinic samples of blood, feces and tumor tissue is used to detect simultaneously as in animal model specimens. Finally, validation and correlation detection are carried out based on univariate and multivariate analysis. This study provides new principles and techniques for the prevention and control of immune metabolism of malignant tumor CRC from the perspective of hygienic analytical chemistry.