Genetic evidence from Mendelian randomization strengthens the causality between oral microbiome and chronic obstructive pulmonary disease.

Epidemiological studies have reported controversial links between the oral microbiome and chronic obstructive pulmonary disease (COPD). Therefore, this study aimed to investigate the causal relationship between the oral microbiome and COPD via Mendelian randomization (MR) and to explore the impact of genetic variation on the oral microbiome to develop more precise healthcare strategies. The latest genome-wide association study data on the oral microbiome and COPD from East Asian populations were extracted and used for the two-sample MR analysis. Integrated methods (including inverse variance weighting, weighted median, and MR-Egger) were applied to comprehensively evaluate casualties. Subsequently, a sensitivity analysis was performed. Totally, 8 bacterial species in the tongue dorsum and 10 bacterial species in saliva were found to have causal relationships with COPD, which involved 9 genera (Prevotella, Streptococcus, Aggregatibacter, Gemella, Haemophilus, Lachnoanaerobaculum, Neisseria, Actinomyces, and Lancefieldella). Overall, this study supported the causal relationships between the oral microbiome and COPD and uncovered the potential role of the oral microbiome in the oral-lung axis. Clinically, this study also recommended that patients with poor oral hygiene (such as periodontitis and smoking) should be regularly assessed for their pulmonary condition and that COPD patients should receive periodic periodontal treatment. Importantly, the oral microbiome identified in this study may serve as a novel target for the prevention, diagnosis, and treatment of COPD in future clinical practice.