Targeting Gut Microbiota Metabolites to Prevent Liver Cancer

项目摘要/摘要 肝细胞癌已成为癌症相关疾病的主要原因。 全球和美国的死亡人数。元基因组学研究正在揭开这个肠道的面纱 微生物区系失调可能对肝细胞癌患者具有诊断潜力。有趣的是，我们的 之前发表的《细胞》杂志强调，富含可发酵纤维菊粉的饮食 可作为诱因，在已有肠道生物失调的小鼠中诱发肝细胞癌。烧蚀 肠道微生物区系通过抗生素和无菌条件完全根除 菊粉诱导的肝癌，这导致了肠道微生物区系如何对 从治疗的角度来看，在肠道微生物区系中， 专门针对阻碍肝细胞癌。因此，我们首先发现了这种肝癌表型。 基因改变的小鼠，但为了这个提议，我们创造了肠道反生野生型 (WTDYS)小鼠通过广泛饲养和杂交培养来具体研究其作用 菊粉诱导的肝细胞癌患者肠道微生物区系的变化。通过16S rRNA测序，我们发现 WTDYS小鼠重现了与肝癌相关的微生物区系，其中包括过度生长 产短链脂肪酸(SCFA)和次级胆汁酸(2°BA)的梭状芽孢杆菌 物种和条件致病菌，如γ-变形杆菌。而粪便和血清 用含菊粉的饲料喂养WTDYS小鼠的内容物正在进行 代谢组学分析，我们预计SCFA和2°BA的水平将显著上升 在相关的细菌水华上，这将类似于我们最初的模型 遗传缺陷。有趣的是，这两种肠道代谢物最近都在 导致不变自然杀伤T细胞(INKT)严重减少但扩大的文献 调节性T(Treg)细胞丰度，这将下调抗肿瘤反应和 分别支持免疫抑制。根据最近的洞察，我们进行了肝脏 用流式细胞术分离和鉴定WTDYS小鼠免疫细胞 减轻了iNKT水平，但Treg细胞数量过多。我们之前的研究和初步的 数据引导我们得出一个中心假设，即肠道微生物区系依赖于免疫抑制 是菊粉诱导的肝细胞癌的主要致病因子。在目标1中，我们将实施药理学 以及阻断SCFA产生和激活SCFA受体的基因干预， 虽然Aim 2将采用药物和饮食干预措施来抑制2°BA的产生， 我们认为这将是两种独立但又相互关联的减少菊粉的方法- 通过恢复抗肿瘤免疫监视诱导肝细胞癌。

PROJECT SUMMARY/ABSTRACT Hepatocellular carcinoma (HCC) has emerged as a leading cause of cancer-related deaths globally and in the United States. Metagenomic studies are unveiling that gut microbiota dysbiosis may possess diagnostic potential for HCC patients. Intriguingly, our previous Cell publication highlights that a diet enriched with the fermentable fiber inulin can act as the trigger to induce HCC in mice with preexisting gut dysbiosis. Ablation of the gut microbiota through antibiotics and germ-free conditions completely eradicated inulin-induced HCC, which leads to question HOW does the gut microbiota contribute to HCC and, on the therapeutic standpoint, WHAT within the gut microbiota can be specifically targeted to impede HCC. Accordingly, we first found this HCC phenotype in genetically altered mice but for this proposal we have generated gut dysbiotic wild-type (WTDYS) mice through extensive breeding and cross fostering to study specifically the role of gut microbiota in inulin-induced HCC. Through 16S rRNA sequencing, we found that WTDYS mice recapitulated the HCC-associated microbiota, which includes an overgrowth of short chain fatty acid (SCFA)- and secondary bile acid (2° BA)-producing Clostridia species and opportunistic pathogens like γ-Proteobacteria. While the fecal and serum contents from WTDYS mice fed on inulin containing diet are in the process for metabolomics analysis, we expect to have a striking elevation of SCFA and 2° BA based on the associated bacterial blooms, which would be analogous to our original model with genetic deficiency. Intriguingly, both gut metabolites have been recently delineated in the literature to cause a severe reduction of invariant natural killer T (iNKT) cells but expand regulatory T (Treg) cell abundance, which would downregulate anti-tumor responses and favor immunosuppression, respectively. From this recent insight, we performed hepatic immune cell isolation and characterization via flow cytometry in WTDYS mice and identified mitigated levels of iNKT but overpopulated Treg cells. Our previous study and preliminary data lead us to the central hypothesis that gut microbiota-dependent immunosuppression is a main contributor to inulin-induced HCC. In Aim 1, we will implement pharmacologic and genetic interventions to blockade SCFA production and activation of SCFA receptors, while Aim 2 will apply pharmacologic and dietary interventions to inhibit 2° BA production, which we posit will be two independent, but inter-related, approaches to abate inulin- induced HCC by restoring anti-tumor immunosurveillance.