Abstract / Summary
Abstract Background: Exacerbations of chronic obstructive pulmonary disease (ECOPDs) are frequently triggered by infections and represent major drivers of disease progression. The salivary microbiota may reflect microbial changes relevant to the respiratory tract and serve as a key reservoir for lower airway colonization, but its temporal dynamics during ECOPD remain poorly characterized. We hypothesized that ECOPD occurrence could be accompanied by coordinated temporal changes in the salivary microbiota and in the local inflammatory profile. Methods: Thirty-three patients with COPD were followed over a 6-month period with monthly saliva sampling. Of these, patients who experienced an ECOPD underwent additional dense sampling every two days during the exacerbation. In total, 251 saliva samples were collected. Participants were characterized using clinical data and salivary microbiota profiling. Results: ECOPDs were associated with microbiota shifts of greater magnitude than steady-state variation (LMER on weighted UniFrac, group × time-point interaction: F = 23, p < 0.0001). These shifts were characterized by transient pathobiont blooms, including Haemophilus , Pseudomonas and Escherichia, and an early reduction in microbial diversity in approximately half of the patients. Microbial changes further coincided with enrichment of inferred functional pathways previously linked to pathogenesis. Following ECOPDs, the salivary microbiota of most patients more closely resembled the pre-exacerbation state than the exacerbation peak. Conclusions: Despite patient-specific variability, ECOPDs were associated with recurring patterns of salivary microbiota perturbation. These findings suggest that saliva may capture ECOPD-associated microbial dynamics and warrant further investigation in larger cohorts.