Extracellular vesicle-encapsulated microRNAs and respiratory health among American Indians in the Strong Heart Study.

ABSTRACT

BACKGROUND: American Indian populations have experienced marked disparities in respiratory disease burden. Extracellular vesicle-encapsulated microRNAs (EV-miRNAs) are a novel class of biomarkers that may improve recognition of lung damage in indigenous populations. RESEARCH QUESTION Are plasma EV-miRNAs viable biomarkers of respiratory health in American Indian populations? STUDY DESIGN AND METHODS: The Strong Heart Study is a prospective cohort study that enrolled American Indians aged 45-74 years. EV-miRNA expression was measured in plasma (1993-1995). Respiratory health outcomes including pre-bronchodilator forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and respiratory symptom burden were ascertained in the same study visit. Club cell secretory protein (CC-16), an anti-inflammatory pneumoprotein implicated in COPD pathogenesis, was measured in serum. Linear and logistic regression were used for statistical analyses. Biological pathway analyses were used to elucidate gene targets of significant EV-miRNAs. RESULTS: Among 853 American Indian adults, three EV-miRNAs were associated with FEV1, four EV-miRNAs were associated with FVC, and one EV-miRNA was associated with FEV1/FVC (P<0.05). Increased miR-1294 expression was associated with higher odds of airflow limitation (OR 1.29, 95% CI 1.07-1.55), while increased expression of miR-1294 (OR 1.32, 95% CI 1.07-1.63) and miR-532-5p (OR 1.57, 95% CI 1.02-2.40) was associated with higher odds of restriction. Increased miR-451a expression was associated with lower odds of exertional dyspnea (OR 0.71, 95% CI 0.59-0.85). Twenty-two EV-miRNAs were associated with serum CC-16 levels (q<0.05), suggesting EV-miRNAs may play a role in the pathway linking CC-16 to COPD pathogenesis. A pathway analysis showed key EV-miRNAs targeted biological pathways that modulate inflammation, immunity, and structural integrity in the lungs. INTERPRETATION: Circulating EV-miRNAs are novel mechanistic biomarkers of respiratory health and may facilitate the early detection and treatment of lung damage in American Indian populations that have been disproportionately affected by chronic lung diseases.