Preliminary Study On The Structural Characteristics Of Gut Microbiota In Lung Cancer Patients

Objective:To explore the structural characteristics of intestinal microbiota in lung cancer patients and investigate the correlations between intestinal flora and lung cancer occurrence,so as to provide new ideas for the diagnosis,treatment and even prevention of lung cancer.Materials and methods:In the first and second parts of the study,a single-center and case-control study was conducted at the Hangzhou First People’s Hospital between September 2019 and July 2020.Patients diagnosed with lung cancer by pathological histology were recruited for the study（LC）,age-and sex-matched healthy people were recruited as healthy control group（HC）during the same period.And lung caner patients were divided into lung adenocarcinoma group（AC）and Squamous cell lung cancer group（SCC）according to pathological diagnosis.Fresh stool samples and relevant clinical data were collected from the study subjects.The genomic DNA was extracted and PCR amplification was performed on the V3-V4 high variant region of the 16S rRNA gene of intestinal microorganisms,and finally high-throughput sequencing was performed on Illumina NovaSeq.The intestinal flora diversity,species composition,LEfSe,and so on were analyzed to compare the differences in microbial species and diversity between lung cancer patients and healthy people,as well as the differences in intestinal flora distribution between lung adenocarcinoma and Squamous cell lung cancer patients,and to screen the microbial species significantly associated with the occurrence of lung cancer.The third part of the study consecutively enrolled patients who were diagnosed with lung cancer by a combination of pathology and clinical manifestations in Hangzhou First People’s Hospital between October 2018 and March 2019 as study subjects.According to the pathological diagnosis and stage,all participates were divided into four groups:stageⅠ,stage Ⅱ,stage Ⅲ,and stage Ⅳ.Fresh stool samples and related clinical data of the study subjects were collected,genomic DNA was extracted,and the content of Veillonella in stool was detected by absolute quantitative Q-PCR method to investigate the relationship between the content of Veillonella and the pathological staging of lung cancer.Results:A total of 39 patients with lung cancer were included in the first and second part of the study,including 8 cases of squamous carcinoma,26 cases of adenocarcinoma,2 cases of large cell lung cancer,and 3 cases of small cell lung cancer.40 cases of healthy population were included in the HC group.There was no significant difference between the two study groups in terms of age,gender（P>0.05）.A total of 90 patients with lung cancer were included in the third part of the study,including 35 patients with stage Ⅰ,7 patients with stage Ⅱ,26 patients with stage Ⅲ,and 22 patients with stage Ⅳ.There was no significant difference in age,and gender among the four study groups（P>0.05）.Alpha diversity analysis showed no significant differences between LC and HC groups,and among AC,SCC and HC groups.Beta diversity analysis showed that LC and HC could be distinguished from each other,show that the structure of the gut microbiota between LC and HC were significantly different.Taxonomic analysis of the gut microbiota revealed that there were significantly different microorganisms at all levels between the LC and HC.LEfSe analysis showed that the abundance of Enterococcus,Enterococcus faecium,Veillonella,Agathobacter,Megasphaera,and Anaerostipes were significantly increased in LC group,and there was a significant positive correlation between Megasphaera,Veillonella and Platelet/Lymphocyte（PLR）.Compared with HC group,the abundance of Megasphaera and Erysipelatoclostridium spp.were significantly higher in AC group,while the abundance of Enterococcus,Veillonella,Selenomonas₄ and Eubacterium_eligens_group were significantly more abundant in SCC group.In the third part of the study,there was a trend of increasing abundance of Veillonella with increasing pathological stage of lung cancer.Conclusion:The composition of the Gut microbiota community of lung cancer patients is significantly different with that of the healthy population,as evidenced by the significantly higher abundance of key pathogenic Enterococcus-Enterococcus faecium,Veillonella,Agathobacter,Megasphaera,and Anaerostipes in LC patients.Lung adenocarcinoma and Squamous cell lung cancer have their own unique intestinal flora.In addition,the amount of Veillonella in the intestine may be closely related to the pathological stage of lung cancer.