Human Lungs Airway Epithelium Upregulate MicroRNA-17 and MicroRNA-548b in Response to Cold Ischemia and Ex Vivo Reperfusion.

BACKGROUND: Lung ischemia-reperfusion injury after transplantation is associated with worse clinical outcomes. MicroRNA (miR) are critical regulators of gene expression that could provide potential targets for novel gene therapy. Herein, we aim to examine the feasibility of using the ex vivo lung perfusion (EVLP) platform to examine the changes in miR expression in human lungs in response to cold ischemia and ex vivo reperfusion (CI/EVR). METHODS: Twenty-four human lungs were perfused in cellular EVLP system for 2 h, and tissue samples were obtained before and after EVLP as well as from control donors. MicroRNA expression profiling of the lung tissue was performed using next-generation sequencing and downstream predicted target genes were examined. In situ hybridization assay of the validated miR was used to identify the expressing cell type. RESULTS: After 2 h of EVLP, cytokines production was significantly increased (IL-1ß, IL-6, IL-8, IL-10, and TNF-α). MicroRNA sequencing identified a significant change in the expression of a total of 21 miR after CI and 47 miR after EVR. Validation using quantitative polymerase chain reaction showed significant upregulation of miR-17 and miR548b after CI/EVR. Downstream analysis identified abundant inflammatory and immunologic targets for miR-17 and miR-548b that are known mediators of lung injury. In situ hybridization assays detected positive signals of the 2 miR expression in alveolar epithelial cells. CONCLUSIONS: This study demonstrates the feasibility of using the EVLP platform to study miR signature in human lungs in response to CI/EVR. We found that miR-17 and miR-548b were upregulated in alveolar epithelial cells after CI/EVR, which merit further exploration.

Increased Mutagen Sensitivity and DNA Damage in Pulmonary Arterial Hypertension.

RATIONALE: Pulmonary arterial hypertension (PAH) is a serious lung condition characterized by vascular remodeling in the precapillary pulmonary arterioles. We and others have demonstrated chromosomal abnormalities and increased DNA damage in PAH lung vascular cells, but their timing and role in disease pathogenesis is unknown. OBJECTIVES: We hypothesized that if DNA damage predates PAH, it might be an intrinsic cell property that is present outside the diseased lung. METHODS: We measured DNA damage, mutagen sensitivity, and reactive oxygen species (ROS) in lung and blood cells from patients with Group 1 PAH, their relatives, and unrelated control subjects. MEASUREMENTS AND MAIN RESULTS: Baseline DNA damage was significantly elevated in PAH, both in pulmonary artery endothelial cells (P < 0.05) and peripheral blood mononuclear cells (PBMC) (P < 0.001). Remarkably, PBMC from unaffected relatives showed similar increases, indicating this is not related to PAH treatments. ROS levels were also higher (P < 0.01). DNA damage correlated with ROS production and was suppressed by antioxidants (P < 0.001). PBMC from patients and relatives also showed markedly increased sensitivity to two chemotherapeutic drugs, bleomycin and etoposide (P < 0.001). Results were consistent across idiopathic, heritable, and associated PAH groups. CONCLUSIONS: Levels of baseline and mutagen-induced DNA damage are intrinsically higher in PAH cells. Similar results in PBMC from unaffected relatives suggest this may be a genetically determined trait that predates disease onset and may act as a risk factor contributing to lung vascular remodeling following endothelial cell injury. Further studies are required to fully characterize mutagen sensitivity, which could have important implications for clinical management.