Microbiome In The Blood Stool Of Patients With Lung Cancer Compared With Healthy Controls

Objective: At present,lung cancer is the highest mortality rate among Chinese residents.Smoking is the most important cause of lung cancer,meanwhile,industrial exposure,air pollution,and genetic mutations are also responsible for lung cancer.Microbial infections are one of the leading causes of increased cancer mortality.In recent years,a number of studies have shown that gut microbiome is associated with the occurrence and development of lung cancer.Previous studies found differences in microbiota communities of lung cancer patients and a control group in saliva samples,bronchoalveolar lavage fluid and lung tissue and the microbiota dysbiosis may promote the development of lung cancer.The aim of this study was to determine the correlation and differences between blood and gut microbiome in lung cancer patients and healthy controls,and to provide new options for clinical application of lung cancer treatment further.Methods: In this experiment,we collected blood and stool samples from lung cancer patients and healthy controls.The DNA in the blood and stool samples of the two groups were extracted and the 16 S rDNA V1V2 region was amplified by using polymerase chain reaction(PCR),the library was established,then sequenced by Illumina sequencing platform,and QIIME software was used for subsequent analysis.(1)Use the OTU dilution curve to assess whether the sample sequencing amount is sufficient to accurately reflect the vast majority of the information of the microbiome,and also to compare the richness of species in different samples;(2)Evaluate diversity within a particular region or ecosystem through Alpha diversity,which means intra-sample diversity;(3)Evaluate the diversity between the sample and the sample by Beta diversity to reflect the difference in species community composition within each sample group and between each sample;(4)Analysis of lung cancer and healthycontrols by LEfSe,looking for species with significant differences in abundance between groups,which means biomarkers;(5)Analysis of the metabolic processes of environmental adaptation of community samples by KEGG metabolic pathway differences.P<0.05 has a significant statistical difference.Results: A total of 38 lung cancer patients and 30 healthy control volunteers were enrolled in our hospital and outer hospital in this study during February 2017 to May2017.By analyzing the sequencing of lung cancer patients and healthy controls,the sequencing results of this experiment are reliable,and the sequencing depth reaches the standard,which can accurately reflect the vast majority of the information of the microbiome in the blood and stool samples of the lung cancer group and the healthy control group.The Shannon-Weiner index of blood microbiome in healthy control group is higher than that in lung cancer group(P=4.83×10^6,P<0.05,Wilcoxon test),indicated that the diversity and abundance distribution of blood microbiome in healthy control group was better than that in lung cancer group.The results of PCoA analysis showed that there was a significant difference between the blood and stool of the two groups,which was closely related to the environment in which the blood microbiome and the gut microbiome exist.Through LEfSe analysis,we found that the biomarkers of the lung cancer group and the healthy control group were significantly different.Several taxa have been found to be enriched in lung cancer group compared with healthy control group.The genus Faecalibacterium and family Ruminococcaceae were only enriched in blood samples from lung cancer patients.Moreover,the two families Lachnospiraceae,Enterobacteriaceae,and the order Clostridiales were significantly more abundant in both blood samples and stool samples of lung cancer group(LDA>3),which indicating that the diversity and abundance distribution of the strains in the blood microbiome and the gut microbiome have changed significantly.Finally,we used STAMP software to infer the KEGG pathways between healthy controls and lung cancer patients,and twenty-five pathways were significant differences between healthy control group and lung cancer group.Conclusions: The differences between the lung cancer group and the healthycontrol group may play a role in the occurrence and development of lung cancer.