Difei Academic | mNGS reveals the characteristics of sputum microbial flora in patients with different phenotypes of acute exacerbation of COPD

Introduction

Recently, the Department of Respiratory and Critical Care Medicine of Huai'an First People's Hospital Affiliated to Nanjing Medical University, in collaboration with Diffei Medical, published an article in Microbial Pathogenesis (IF=3.8) on different phenotypes of chronic obstructive pulmonary disease (chronic obstructive pulmonary disease) during acute exacerbations. Analysis and study of sputum microbial flora in patients with pulmonary disease (COPD).

This study collected sputum samples from 29 patients with acute exacerbations of COPD (AECOPD) of different phenotypes before treatment, used mNGS technology to analyze the differences in sputum microbial flora, and explored the sputum microorganisms. The relationship between bacterial flora and clinical indicators of patients in the acute exacerbation phase has certain guiding significance for personalized treatment of AECOPD patients.

Research Background

COPD is primarily a heterogeneous smoking-related disease characterized by chronic respiratory symptoms and persistent airflow limitation.In China, COPD is one of the top five causes of life lost.AECOPD refers to an exacerbation of respiratory symptoms, usually accompanied by an exacerbation of local or systemic inflammation, resulting in decreased lung function and increased mortality.

There is significant heterogeneity in the clinical manifestations, disease progression, and treatment response of COPD patients, which are affected by biological genotype and environmental factors.The COPD phenotype is a composite characteristic of one or more diseases that is associated with clinical symptoms, treatment response, and prognosis.This makes it possible to identify differences between COPD patients with different phenotypes and develop more personalized treatments.

Multiple studies have shown that changes in the lung microbiota of patients with COPD are related to the severity and frequency of exacerbations.However, regarding the emphysema phenotype (E), chronic bronchitis with emphysema phenotype (B+E), and asthma-COPD overlap phenotype (ACO) ) There are few studies on the differences in sputum microbiota among AECOPD patients.

This study included 29 patients who experienced AECOPD. According to different COPD phenotypes, the patients were divided into three groups: E, B+E and ACO. mNGS technology was used to detect and analyze the microbial flora characteristics of AECOPD patients with different phenotypes.

Distribution and diversity of sputum microbiota

Distribution and diversity of sputum microbiota

By comparing the composition and diversity of bacterial flora in three groups of AECOPD patients with different phenotypes, we found thatDuring acute exacerbations, the composition of the microbiota was similar among the three groups of patients。

The most abundant phyla in sputum are Firmicutes, Actinobacteria, and Proteobacteria; the main genera include Roseburia, Streptococcus, and Actinobacteria; the main bacterial species include Roseburia mycosalis and Cariobacteria. Neisseria sicca, Neisseria sicca, etc.There were no significant differences in alpha diversity and beta diversity among the three groups.

Figure 1 Distribution of sputum microbial flora in three groups at the species level

Figure 2 Beta diversity of sputum microbial flora in three groups

Highly abundant differential species between groups

There were no statistically significant differences in the phylum and genus levels of bacterial flora in the sputum of the three groups of patients.

The results showed that at the phylum level, the relative abundance of actinomycetes in group B+E increased slightly but not significantly compared with other groups; at the genus level, the relative abundance of Lactobacillus and Streptococcus in ACO There was a slight increase compared with other groups, and the relative abundance of Roseburia in group B+E was increased compared with the other two groups.At the species level, except for the relative abundance of Streptococcus mitis in the ACO group, which was significantly increased compared with other groups, the relative abundance of Streptococcus sanguinis and R. mycoides in group B+E was slightly increased compared with other groups, and the relative abundance of Haemophilus influenzae in group E was slightly increased compared with other groups. The relative abundance of Bacilli also increased compared with other groups, but there was no significant difference.

Figure 3 Relative abundance differences of microbial flora in sputum among the three groups at the species level(* indicates P<0.05)

Interactions between microbiota groups

The study foundGroups B+E, E, and ACO have unique microbial symbiosis networks at the species level。

Candidatus Saccharibacteria oral taxon TM7x and Fusobacterium necrophorum are the core nodes of the ACO and E symbiotic networks, respectively.They are positively correlated and act synergistically with some species.In B+E, Haemophilus influenzae and Klebsiella pneumoniae had a synergistic effect.In addition, some species have been found to play synergistic or antagonistic roles respectively between different phenotypes.

Figure 4 Microbial network at the species level among the three groups.The three geometric figures represent species in the three groups.The square represents B+E, the triangle represents group E, and the circle represents group ACO.The area of ​​each geometric figure is related to the relative abundance of microbial groups; different colors represent different microbial groups, and the same color represents the same phylum; purple and blue lines represent co-occurrence and mutual exclusion respectively.

Correlation analysis between bacterial classification and clinical indicators

Spearman correlation analysis showed that,The relative abundance of Streptococcus sanguinis is positively correlated with peripheral blood neutrophil ratio and NLR。

Streptococcus sanguis is one of the normal oral flora, but the inflammatory response caused by colonization of pathogenic bacteria or imbalance of flora plays a key role in the occurrence and development of COPD. Studies speculate that the increase of this bacteria in B+E is related to the increase in COPD inflammation.Melanin-producing Prevotella is negatively correlated with age, peripheral blood neutrophil ratio and NLR, suggesting that this bacterium may be a beneficial bacterium and has anti-inflammatory effects in AECOPD.

Figure 5. Correlation analysis between bacterial classification and clinical indicators in sputum.Red and green dots represent clinical indicators and bacterial taxa, respectively.Red and blue edges indicate positive and negative correlations between sputum bacterial taxa and clinical indicators respectively (* and ** indicate P < 0.05 and 0.01, respectively).

Summarize

This study is the first to analyze the microbial flora in the sputum of patients with different phenotypes of AECOPD and its relationship with clinical indicators, and explore the relationship between the microbial flora and inflammation in AECOPD.These findings will help in future studies to change patient prognosis by inhibiting specific bacterial taxa associated with inflammation, and have certain guiding significance for personalized treatment.