Analysis of Respiratory Microbiota Characteristics in Patients with COPD and High-Risk Populations Using 16S rRNA Technology

Objective: To compare respiratory microbiota across patients with COPD, individuals at high risk for COPD, and healthy controls, and to assess associations with COPD severity. Methods: From January 2022 to December 2023, participants were enrolled into four groups: previously diagnosed COPD (PVD-COPD, n=16), newly diagnosed COPD (PLD-COPD, n=16), high-risk individuals (HR, n=20), and healthy controls (HP, n=20). Sputum and saliva samples underwent 16S rRNA gene sequencing. Microbial diversity and taxonomic composition were compared among groups. In patients with COPD, correlations between sputum microbiota features and GOLD grade were analyzed. Results: Seventy-two subjects were included. Alpha diversity (Ace and Chao1) and beta diversity differed significantly among groups (all P< 0.05). Dominant phyla were similar across groups (Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria), whereas genus-level profiles differed, with 10 genera showing significant between-group differences (mean abundance > 1%). Within the COPD cohort, Ace and Chao1 were positively correlated with GOLD grade (r=0.3659, P=0.0394). A Streptococcus -dominant pattern was more frequent in GOLD 1– 2, while a Neisseria -dominant pattern was more frequent in GOLD 3– 4. Conclusion: Respiratory microbiota composition differs across healthy controls, high-risk individuals, and COPD patients. In COPD, microbiota diversity and dominant genera are associated with disease severity, supporting a link between respiratory microbiota structure and COPD progression. Keywords: pulmonary disease, chronic obstructive, 16S rRNA, high-risk population, respiratory microbiota