Targeting Gut Microbiota Metabolites to Prevent Liver Cancer

项目总结/摘要 肝细胞癌（HCC）已经成为癌症相关疾病的主要原因。 全球和美国的死亡人数。宏基因组研究揭示了肠道 微生物群生态失调可能对HCC患者具有诊断潜力。有趣的是，我们 以前的细胞出版物强调，富含可发酵纤维菊粉的饮食 可以作为诱发肝癌的触发因素，在预先存在肠道生态失调的小鼠中。消融 肠道微生物群通过抗生素和无菌条件完全根除 菊糖诱导的HCC，这导致了一个问题，肠道微生物群如何有助于 从治疗的角度来看，肠道微生物群中的 专门用于阻止HCC。因此，我们首先在2004年发现了这种HCC表型。 基因改变的小鼠，但对于这个建议，我们已经产生了肠道生态失调的野生型 （WTDYS）小鼠通过扩繁和杂交培育来具体研究 菊粉诱导的肝细胞癌中肠道微生物群的变化。通过16 S rRNA测序，我们发现， WTDYS小鼠重现了HCC相关的微生物群，其中包括过度生长 产生短链脂肪酸（SCFA）和次级胆汁酸（2° BA）的梭菌 物种和机会致病菌如γ-变形菌。粪便和血清 来自喂食含菊粉饮食的WTDYS小鼠的内容物正在进行 通过代谢组学分析，我们预计SCFA和2° BA的显著升高基于 相关的细菌大量繁殖，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被描述在 文献报道导致恒定的自然杀伤T（iNKT）细胞严重减少，但扩大了 调节性T（Treg）细胞丰度，这将下调抗肿瘤反应， 分别有利于免疫抑制。根据最近的观察，我们对肝脏进行了 在WTDYS小鼠中通过流式细胞术分离和表征免疫细胞，并鉴定 iNKT水平降低但Treg细胞过度增殖。我们先前的研究和初步的 数据使我们得出一个中心假设，即肠道微生物群依赖性免疫抑制 是菊粉诱导的HCC的主要贡献者。在目标1中，我们将实施药理学 以及阻断SCFA产生和SCFA受体活化的遗传干预， 而目标2将应用药理学和饮食干预来抑制2° BA的产生， 我们认为这将是两个独立的，但相互关联的，减少菊粉的方法- 通过恢复抗肿瘤免疫监视诱导HCC。

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.