Metabolites regulating macrophage function in colorectal cancer

摘要 大多数结直肠癌（CRC）患者对免疫检查点抑制剂治疗没有反应，这是由于T细胞功能低下。 细胞浸润和免疫抑制环境。结直肠癌的病理特征是独特的， 肿瘤微环境中复杂的微生物组。不同的细菌种类和代谢产物 肿瘤可以改变浸润免疫细胞的活性和功能，调节肿瘤的免疫环境。 因此，了解富含肿瘤的代谢物如何改变免疫环境对于 开发新的微生物群/代谢物干预方法。 我们观察到类似于M2样表型的巨噬细胞在CRC样本中的比例较高 与患者匹配的正常组织相比。我们对结直肠癌组织的代谢组学分析显示， 必需氨基酸，其与改变的巨噬细胞表型强烈相关。此外，单核细胞 暴露于肿瘤富集的代谢物如色氨酸和苯丙氨酸增加与肿瘤相关的标记物。 免疫抑制性巨噬细胞然而，微生物衍生的代谢物是否改变巨噬细胞 极化，并有助于免疫抑制表型，这可以影响免疫环境， CRC，仍然未知。我们假设，大肠癌中代谢物的富集改变与 免疫抑制性巨噬细胞和关键肿瘤富集代谢物调节巨噬细胞 表型。在目标1中，我们将评估肿瘤富集代谢物对巨噬细胞表型的影响。在 目的2，我们将在功能上验证影响CRC类器官中巨噬细胞极化的关键代谢物 共培养模式 我们将使用代谢物筛选方法，使用人原代外周血单核细胞， 健康供体和CRC患者，以评估肿瘤富集的代谢物是否可以促进 免疫抑制巨噬细胞表型。此外，我们将使用人类微卫星稳定和 与患者匹配的未分化单核细胞和肿瘤细胞共培养的微卫星不稳定CRC类器官 富集代谢物以评估巨噬细胞亚型的变化。我们将找出关键的代谢物， 巨噬细胞表型和功能，有助于持续的免疫抑制肿瘤环境。 冲击确定肿瘤富集代谢物和巨噬细胞表型之间的相互作用将增加 通过巩固免疫环境可以被操纵的前提， 通过内源性代谢调节。

ABSTRACT Most colorectal cancer (CRC) patients do not respond to immune checkpoint inhibitor therapies due to poor T cell infiltration and an immune suppressive environment. The pathological characteristics of CRC are unique due to the complex microbiome in the tumor microenvironment. Diverse bacterial species and metabolites in the tumor can alter the activity and function of infiltrating immune cells, regulating the tumor's immune environment. Therefore, understanding how tumor-enriched metabolites change the immune environment is crucial for developing novel microbiota/metabolite intervention approaches. We observed that macrophages resembling an M2-like phenotype are in a higher proportion in CRC samples compared to patient-matched normal tissues. Our metabolomic analysis of CRC tissues showed increases in essential amino acids, which strongly correlate with altered macrophage phenotype. Further, monocytes exposed to tumor-enriched metabolites such as tryptophan and phenylalanine increase markers associated with immunosuppressive macrophages. However, whether microbial-derived metabolites alter macrophage polarization and contribute to immunosuppressive phenotypes, which can influence the immune environment in CRC, remains unknown. We hypothesize that altered enrichment of metabolites in CRC correlates with immunosuppressive macrophages and that critical tumor-enriched metabolites modulate the macrophage phenotypes. In Aim 1, we will assess the impact of tumor-enriched metabolites on macrophage phenotype. In Aim 2, we will functionally validate key metabolites influencing macrophage polarization in CRC organoid coculture models. We will use a metabolite screening approach using human primary peripheral blood mononuclear cells from healthy donors and CRC patients to assess whether tumor-enriched metabolites can promote immunosuppressive macrophage phenotypes. In addition, we will use human microsatellite stable and microsatellite instable CRC organoids cocultured with patients matched undifferentiated monocytes and tumor- enriched metabolites to assess shifts in macrophage subtypes. We will identify critical metabolites that can alter macrophage phenotype and function, contributing to a sustained immunosuppressive tumor environment. Impact. Determining interactions between tumor-enriched metabolites and macrophage phenotype will increase the clinical implications of this study by solidifying the premise that the immune environment can be manipulated by endogenous metabolic regulation.