Characteristics of lower respiratory tract microbiota in the patients with post-hematopoietic stem cell transplantation pneumonia

Abstract

BackgroundPneumonia is a leading cause of non-relapse mortality after hematopoietic stem cell transplantation (HSCT), and the lower respiratory tract (LRT) microbiome has been proven to be associated with various respiratory diseases. However, little is known about the characteristics of the LRT microbiome in patients with post-HSCT compared to healthy controls (HC) and community-acquired pneumonia (CAP).MethodsBronchoalveolar lavage samples from 55 patients with post-HSCT pneumonia, 44 patients with CAP, and 30 healthy volunteers were used to detect microbiota using 16S rRNA gene sequencing.ResultsThe diversity of the LRT microbiome significantly decreased in patients with post-HSCT pneumonia, and the overall community was different from the CAP and HC groups. At the phylum level, post-HSCT pneumonia samples had a high abundance of Actinobacteria and a relatively low abundance of Bacteroidetes. The same is true for non-survivors compared with survivors in patients with post-HSCT pneumonia. At the genus level, the abundances of Pseudomonas, Acinetobacter, Burkholderia, and Mycobacterium were prominent in the pneumonia group after HSCT. On the other hand, gut-associated bacteria, Enterococcus were more abundant in the non-survivors. Some pathways concerning amino acid and lipid metabolism were predicted to be altered in patients with post-HSCT pneumonia.ConclusionsOur results reveal that the LRT microbiome in patients with post-HSCT pneumonia differs from CAP patients and healthy controls, which could be associated with the outcome. The LRT microbiota could be a target for intervention during post-HSCT pneumonia.

Evaluation of clinical characteristics and risk factors associated with Chlamydia psittaci infection based on metagenomic next-generation sequencing

“…Changes in the diversity or abundance of pulmonary microbiota are related to a variety of chronic respiratory diseases, such as asthma, cystic fibrosis, Bronchiectasis, and chronic obstructive pulmonary disease [ 28 , 33 , 34 ]. The respiratory microbiota may offer resistance to the colonization of respiratory pathogens which also engages in the maturation and maintenance of respiratory physiology and immune homeostasis.…”

Evaluation of clinical characteristics and risk factors associated with Chlamydia psittaci infection based on metagenomic next-generation sequencing

“…Changes in the diversity or abundance of pulmonary microbiota are related to a variety of chronic respiratory diseases, such as asthma, cystic brosis, Bronchiectasis, and chronic obstructive pulmonary disease [27][28][29] . The respiratory microbiota may offer resistance to the colonization of respiratory pathogens.…”

Lung microbiome and origins of the respiratory diseases

“…Immunocompromised patients such as those affected post-hematopoietic stem cell transplantation (HSCT) pneumonia are a case in point. Pseudomonas , Acinetobacter , Burkholderia , and Mycobacterium tend to be frequently identified, and Enterococcus has been significantly associated with mortality in one series ( He et al, 2022a , He et al, 2022b ). Nominally for Pseudomonas pneumonia gut translocation is emphasized rather than usual aspiration of oropharyngeal contents.…”

“…Studies now suggest that the gut-lung axis connecting the intestine and lung alveoli exists and may exert relevant biological functions as gut-brain axis ( Ma et al, 2022 ). The total respiratory microbiome is incomparably smaller than the gastrointestinal one, both regarding total population and occupied area ( Natalini et al, 2022 ; He et al, 2022a , He et al, 2022b ). Systemic distribution of growth hormones, cytokines, chemokines, antimicrobial proteins, lipid mediators, microbial metabolites, endotoxins, amino acids, VOCs and hormones with significant pro- or anti-inflammatory effects can exacerbate or attenuate either the lung or gut diseases at different clinical setting ( Rooks and Garrett, 2016 ; Khan et al, 2021 ).…”