氨对肠道菌群定殖的改变促进多发性骨髓瘤进程的机制研究

Multiple myeloma (MM) has a high risk of recurrence and resistance, which is still a problem to be solved in clinical and urgently requires the exploration of new MM treatment strategies. Studies revealed that some tumorigenesis and development are associated with gut microbiota dysbiosis, and the gut microbiome provides new insights for tumor diagnosis and treatment. Based on our previous metagenomic sequencing of fecal samples from healthy controls and newly diagnosed MM patients, we found imbalanced bacteria composition in MM, being characterized by the significant enrichment of microorganisms from Enterobacteriaceae and Streptococcus. Experiments in vitro and in vivo suggested that the enriched microbes may accelerate MM progression via ammonia metabolism, but the mechanism remains unclear..In this project, to examine the differential microbes identified in previous study and investigate the correlation between microorganisms and MM progression, we will expand the collection of newly diagnosed, relapsed and sequential MM fecal samples. To explore the influence of intestinal flora on MM tumor, and reveal the potential mechanism of NH4+ causing intestinal flora imbalance and accelerating MM development, gut microbiota from MM patients and healthy controls will be transplanted into 5TGM1 MM mouse model and co-cultured with 5TGM1 MM cells, respectively. In addition, the 5TGM1 MM mouse model was given NH4Cl and urea by gavage, respectively, to further verify the influence of NH4+ on tumor progression and the relevant mechanism. In view of the new perspective of gut microbiota dysbiosis involving in MM process and drug-resistance, we will originally explore the basic theory for clinical treatment of MM in this project.

多发性骨髓瘤（Multiple Myeloma, MM）的高复发风险与耐药仍是临床上亟待解决的问题，迫切要求探索新的MM治疗策略。研究揭示多种肿瘤与肠道菌群失调有关联，为肿瘤诊疗提供了新的切入点。课题组基于前期宏基因组测序的健康对照和初诊MM患者粪便样本，发现MM患者的肠道菌群失调，肠杆菌科和链球菌属微生物显著富集。体内外实验提示富集微生物可能通过氨代谢加速MM进程，但机制尚不清楚。.本项目拟扩大收集初诊、复发及序贯MM粪便样本，进一步检验前期识别的差异微生物，及其与MM肿瘤进程的相关性。通过对5TGM1 MM鼠模型移植MM患者和健康人的粪菌；且将5TGM1 MM细胞系与MM患者及健康人的粪菌体外共培养，探究肠道菌群对MM肿瘤的影响，并揭示NH4+导致肠道菌群失调和加速MM肿瘤进程的潜在机制。另外，对5TGM1 MM鼠模型灌胃NH4Cl和尿素，进一步验证NH4+对小鼠肿瘤进程的影响及相关机制。本项目原创性地从失调肠道微生物参与MM肿瘤进程及治疗抵抗这一全新角度，为MM临床治疗探索理论依据。

肠道微生物组的改变与人体健康密切相关，并与多种疾病有关。虽然大量的研究已探索了与多发性骨髓瘤(multiple myeloma，MM)有关的危险因素，但目前对肠道微生物组的作用及其代谢功能的改变在MM的发展中仍所知甚少。.本研究通过宏基因组测序分析来自初诊MM患者和健康对照的粪便样本，首次发现在MM样本中的细菌多样性显著更高。尤其，氮源循环细菌如克雷伯菌(Klebsiella)和链球菌(Streptococcus)在MM中显著富集，且这些MM富集的细菌与宿主代谢显著关联，提示微生物与宿主之间存在较强的代谢相互作用。这些MM富集菌可能是MM进程中尿素氮积累所致。此外，通过对5TGM1小鼠进行粪便微生物移植(FMT)，我们提出了MM富集细菌通过循环尿素氮与MM进展相互作用的机制解释。进一步的实验证实，肺炎克雷伯菌通过谷氨酰胺在小鼠体内的从头合成促进MM的进展，而以谷氨酰胺缺乏饮食喂养的小鼠表现出较慢的MM进展。.总的来说，我们的研究揭示了改变的肠道微生物组在加速MM恶性进展方面的新功能，并提示操纵患者的肠道微生物群可作为MM治疗的新策略。