Correlation Analysis Of Lung Microbiome And Immunity In Sepsis

BackgroundSepsis is a systemic disease of host immunity disorder caused by infection.It is a serious disease all over the world with high mortality.It is very important to confirm the pathogenesis of sepsis and improve its diagnosis and treatment.Microbiome plays an important role in health,and which is closely related to immunity.Microbiome is related to many diseases included cardiovascular diseases,respiratory diseases and so on.In recent years,more and more attention has been paid to the important role of lung microbiome in diseases.The lung-gut axis is a functional axis that establishes the relationship between the lung and the gut through immunity,which is of great significance to the health.And the interaction between the lung and gut microbiome is an important part of all the lung-gut axis function.At present,the mechanism of lung microbiome in the process of sepsis and how the lung-gut axis affects sepsis through immunity are unclear.Exploring the relationship between lung microbiome and immunity in sepsis is helpful to confirm the pathogenesis of sepsis and is of great significance to improve the diagnosis and treatment of sepsis.ObjectiveThis study intends to explore the relationship between lung microbiome and immunity in sepsis.We try to reveal the important role of microbiome of lung-gut axis in sepsis,and confirm the potential impact and mechanism of specific microbiome components on immunity in sepsis.MethodsIn the first part of the clinical study,61 sepsis patients admitted to the intensive care unit(ICU)were included to collect alveolar lavage fluid and feces.The primary end point was 28 days of survival.Through the metagenomic sequencing,Wilcox statistics and LEf Se analysis way,we understand the composition of microbiome of lung and gut in sepsis patients with different prognosis and try to find the specific microbiome components related to the prognosis of sepsis.At the same time,the antibiotic resistance of sepsis was analyzed by functional gene analysis.In the second part of the clinical study,we included 29 patients with sepsis admitted to the ICU.Through the correlation analysis of lung and gut microbiome with immune cells in sepsis patients,we understand the relationship between microbiome of lung-gut axis and immunity.In the third part of the basic study,we use Streptococcus pneumoniae to construct the lung sepsis model.Through the treatment of Enterococcus faecium,the pulmonary cytokines are detected by ELISA,and the differential gene of pulmonary transcriptome is detected by RNAseq.At the same time,the lung of mice were treated with hematoxylin and eosin solution(H&E),besides,the pathological changes of the lungs were observed.ResultsIn the first part,we used metagenome to analyze the microbiome of lung and gut in patients with sepsis.The results showed that the proportion of Enterococcus faecium in the lung microbiome of patients with sepsis survival group was significantly higher(p=0.029),suggesting that Enterococcus faecium(EF)may be a protective factor of sepsis.The metagenome analysis results showed that there are a variety of drug resistance genes in lung and gut microbiome of patients with sepsis,which is a potential "repository" of drug resistance genes,which might be a novel way for the diagnosis and treatment of sepsis.TEM-135 gene was the highest content of drug resistance gene in microbiome of lung,and adeF gene was the highest content of drug resistance gene detected in microbiome of gut.In the second part,we mainly focused on the existence of microbiome of lung-gut axis in sepsis and the correlation between lung-gut axis and immunity.Principal component analysis(PCA)at the phylum and species level showed that composition of microbiome between lung and gut was similar.PCA analysis in the phylum level show that PC1 accounted for 16.57%of the total variation,and PC2 accounted for 12.54%of the total variation.PCA analysis in the species level show that PC1 accounted for 8.77%of the total variation,and PC2 accounted for 7.85%of the total variation.Correlation analysis also suggested that the lung microbiome and gut microbiome of patients with sepsis were significantly correlated with specific immune cells(Correlation coefficient threshold was 0.75).It could be inferred that the microbiome of lung-gut axis may be an important factor affecting the immunity of patients with sepsis.In the third part,the study was based on the conclusion of the first part of clinical research.In this part,we further confirmed the close relationship between lung microbiome and sepsis through the animal model.Firstly,the mouse model of lung sepsis was constructed by Streptococcus pneumoniae.Through the intervention of EF,the effect of EF on immunity in sepsis was explored.The results showed that from the second day after sepsis,the weight of sepsis mice intervened by EF recovered significantly,the expression of sepsis related interleukin-6 in lung tissue decreased,and the degree of pathological injury of lung was relatively reduced.The results of differential gene analysis of lung transcriptome also confirmed the effect of EF in the immunity of sepsis,and the cytokine pathway may be a potential pathway target for EF to affect the immunity of sepsis.ConclusionThis study was based on clinical research and verified by animal experiments,which could prove the important role of lung microbiome in immunity of sepsis.EF had a relatively high proportion in the lung microbiome of patients in the survival group of sepsis,suggesting that EF is a protective factor for the sepsis.There was a significant correlation between microbiome of lung-gut axis and immunity in sepsis.We verified the protective effect of EF in sepsis by constructing a mouse model of lung sepsis.In conclusion,the lung microbiome was closely related to the immunity of sepsis.And microbiome of lung-gut axis played an important role in the immunity of sepsis.Besides,the specific bacterial flora of the lung microbiome is probably an important factor regulating the immunity of patients with sepsis.