Gut Microbiota Predict Pulmonary Infiltrates after Allogeneic Hematopoietic Cell Transplantation

Area of Science:

• Microbiology
• Immunology
• Pulmonology

Background:

• Pulmonary complications (PCs) are a major cause of death after allogeneic hematopoietic stem cell transplantation (HCT).
• Gut microbiota alterations are known to influence HCT outcomes, but their specific role in PCs remains unclear.

Purpose of the Study:

• To investigate the association between gut microbiota composition and the development of PCs following HCT.
• To identify microbial and clinical risk factors for PCs and mortality post-HCT.

Main Methods:

• A single-center observational study included 94 patients undergoing HCT.
• Fecal samples were analyzed using 16S ribosomal RNA sequencing for gut microbiota profiling.
• Patients were monitored for PCs, defined by new abnormal chest imaging findings with respiratory symptoms, up to 40 months post-transplant.

Main Results:

• PCs occurred in 70.2% of subjects, with high comorbidity index and fluoroquinolone use predicting PCs.
• Low baseline gut microbial diversity and dominance of γ-proteobacteria (including respiratory pathogens) were significant predictors of PCs.
• Low diversity was linked to pre-engraftment PCs, while γ-proteobacteria domination predicted post-engraftment PCs and overall mortality.

Conclusions:

• This study provides the first prospective evidence linking gut microbiota changes to PCs after HCT.
• Post-engraftment PCs and γ-proteobacteria dominance are independent predictors of mortality, suggesting a gut-lung axis interaction.
• Further research is needed to explore the mechanisms underlying the gut microbiota's influence on lung complications post-HCT.