Diversity And Succession Of Gut Microbiota In Patients With Diffuse Large B Cell Lymphoma

Background:Although the Diffuse large B-cell lymphoma(DLBCL)is the most common type of adult non-Hodgkin’s lymphoma(NHL),the pathogenesis of DLBCL is not fully understood and the treatment is limited leading to huge challenges in clinical management of this disease.As the so-called second human genome,the microbial genome of the long-lived microorganisms and their metabolites interact with host cells quite easily.The gut microbiota is an indispensable part in the microenvironment of tumor and plays an important role in the occurrence and progression of hematological malignancies.Gut microbiota differs in healthy personnel and patients with untreated as well as treated(chemotherapy)DLBCL,showing a succession in the composition of microbiota.However,there are only a few studies on the role of the gut microbiota in NHL,and the role of gut microbiota in DLBCL has not been reported.The aim of our current study is to investigate the altered composition of gut microiota in patients with DLBCL and microbiota succession following chemotherapy.This study was divided into two parts.Twenty-five patients with newly-diagnosed untreated DLBCL and 26 matched healthy controls were recruited for the first part of study to clarify the altered gut microbiota in patients with untreated DLBCL(1 fecal sample was collected from each person)and 17 patients with newly diagnosed untreated DLBCL and 18 matched healthy controls were enrolled for the second part of study to explore the gut microbiota succession following chemotherapy(1 fecal sample from healthy control and 2 fecal samples from DLBCL patients before and after chemotherapy were collected,respectively).Aims:Our study is to explore the association between gut microbiota and DLBCL,trying to understand whether there exists difference in gut microbiota between patients with DLBCL and healthy volunteers,and gut microbiota succession in DLBCL patients following chemotherapy,and whether there exists a core microbiota or dominant microbiota.Our results from these studies will provide a theoretical foundation for further research on the role of gut microbiota in DLBCL to facilitate drug development and foster novel strategy for the better management of patients with DLBCL.Methods:Twenty-five patients with newly diagnosed untreated patient and 26 matched normal controls were recruited for the first part of this study and 17 patients with newly diagnosed untreated patient and 18 matched normal controls were enrolled for the second part of study.Based on the outcomes following 4 courses of chemotherapy,17 patients with DLBCL were divided into posttreatment patient,complete remission and non-complete remission patient.The microbiota composition of fecal samples from all DLBCL patients and healthy volunteers was examined by 16s rRNA gene sequencing,and analysis of α-diversity and β-diversity was performed.Results:In the first part,a significant difference was observed between untreated patient and normal control on β-diversity analysis.The gut microbiota in patients with untreated DLBCL showed a continuous evolutionary relationship at six levels,including P-Proteobacteria、C-Gammaproteobacteria、O-enterobacteriales、F-Enterobacteriaceae、G-Escherichia-Shigella、S-Escherichia coli,and the abundance was significantly higher than that of the normal control.The results of PICRUSt prediction of metagenome function showed that thiamine metabolism,and phenylalanine,tyrosine and tryptophan biosynthesis were decreased in untreated patient.In the second part,β-diversity analysis showed the abundance of gut microbiota P-Proteobacteria,C-Gammaproteobacteria,O-enterobacteriales,F-Enterobacteriaceae,G-Escherichia-Shigella,S-Escherichia coli was significantly higher in pretreatment patient than that of posttreatment patient,though no significant difference with normal control.Abundance of F-Lactobacillaceae,G-Lactobacillus and S-Lactobacillus fermentum were higher in complete remission patient than that of non-complete remission patient,while the abundance of P-Fusobacteria,C-Fusobacteriia,O-Fusobacteriales,F-Fusobacteriaceae,G-Fusobacterium was lower in posttreatment patient than that of pretreatment patient and normal control following 4 courses of chemotherapy.Conclusions:Results from our current study indicated that the composition of gut microbiota has changed significantly in patients with DLBCL.As the dominant microbiota,Proteobacteria may be involved in the occurrence of DLBCL.In addition,the composition of gut microbiota was altered in DLBCL patients following intervention with 4 courses of chemotherapy.Proteobacteria is no longer the dominant microbiota in DLBCL patients with complete or non-complete remission.Instead,Lactobacillus fermentum became the dominant microbiota in complete remission patient,which was related to the changes in lymphoid tumor and resulted from the gut microbiota succession caused by chemotherapy intervention and tumor extinction.Our results also indicated Lactobacillus fermentum could be completely excluded from the direct action of chemotherapy,although the latter was related to the efficacy of therapy in patients with DLBCL,and the decrease in the abundance of Fusobacteria phylum in posttreatment patient might be caused by the direct action of therapy while the changes in Proteobacteria may excluded from the direct action of chemotherapy with further comfirmation.Lastly,Lactobacillus fermentum may have an inhibitory effect on DLBCL.