Diagnostic and Monitoring Potential of Sputum-Derived miRNAs in Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and progressive respiratory disorder characterized by airflow limitation, chronic inflammation, and structural lung alterations. Despite advances in clinical monitoring, current approaches such as spirometry, symptom scores, and imaging remain limited in capturing disease complexity and early pathophysiological changes. In this context, microRNAs (miRNAs) have emerged as promising molecular biomarkers due to their involvement in key inflammatory and immune pathway regulation. Sputum is gaining attention as a non-invasive and informative matrix for studying COPD. As a surrogate of airway mucus, sputum reflects local pathological processes, including inflammation and tissue damage, and contains biomarkers such as miRNAs. Compared to circulating miRNAs, sputum-derived miRNAs appear to more accurately represent lung-specific alterations. In this review, we focus on works published so far about the identification of miRNAs in COPD sputum. Several miRNAs have been associated with COPD diagnosis, severity, and exacerbations. These findings, including the possible correlation of some miRNAs with sputum biophysical properties, support the value of integrated biomarker approaches. While further large-scale and standardized studies are required to validate the role of COPD miRNAs assessed in sputum, their evaluation in sputum represents a promising tool for improving the diagnosis, phenotyping and monitoring of COPD.