Genetic evidence for a causal relationship between oral bacterial taxa and asthma in east Asian population

Emerging evidence highlights the significant role of microbiota (lung and gut) in the development of asthma. However, the potential effect between oral microbiota and asthma remains poorly understood.

This study performed a bidirectional Mendelian randomization (MR) study using summary statistics from the genome-wide association studies of oral microbiota, immune cell traits and asthma. Various MR analysis methods were employed, including inverse variance weighted (IVW), constrained maximum likelihood model averaging-based method (cML-MA-BIC), maximum likelihood (ML), weighted mode, weighted median, and MR-robust adjusted profile score (MR-RAPS). Additionally, mediation analyses were performed to identify the immune cell traits that mediate these effects.

This study identified 12 oral bacterial taxa and 36 inflammatory cytokines associated with asthma. After identifying the oral microbiota and immune cell characteristics associated with asthma, we applied a mediation MR framework to investigate whether immune cell traits mediate the effect of microbiota on asthma. Finally, we identified eight immune cell traits that mediate asthma caused by bacteria.

Our results highlight the causal associations between oral bacterial taxa, immune cell traits, and asthma, providing evidence that various immune cell traits serve as critical mediators between the oral microbiota and asthma. The link between the oral microbiome and asthma has important implications for clinical practice.