Background: Ceramides are known for their harmful, cell-autonomous effects in cigarette smoke (CS)-triggered chronic obstructive pulmonary disease (COPD), yet their potential role as intercellular signals in COPD pathogenesis remains unclear. This study aims to investigate whether ceramides act as cell-nonautonomous mediators of COPD development by transmitting metabolic stress from pulmonary macrophages to endothelial cells (ECs), compromising endothelial function and thereby orchestrating the pulmonary inflammation.
Methods: We analyzed single-cell RNA sequencing data from human lung tissues and bulk RNA sequencing data from alveolar macrophages (AMs) in COPD patients to investigate the transcriptomic profiles of ceramide biosynthesis enzymes. The expression changes of several key enzymes were validated in human lung sections, AMs isolated from CS-exposed mice, and cigarette smoke extract (CSE)-treated macrophages. Ceramide levels in macrophages and their extracellular vesicles (EVs) were quantified using mass spectroscopy lipidomics. EVs were further characterized by transmission electron microscopy and nanoparticle tracking analysis. The uptake of macrophage-derived EVs by ECs and their effects on endothelial barriers were evaluated in vitro using a co-culture system and in vivo using a CS-exposed COPD mouse model.
Results: CS exposure upregulated enzymes involved in de novo ceramide biosynthesis in pulmonary macrophages, increasing levels of long- and very long-chain ceramides. These ceramides were packaged into EVs and delivered to ECs, where they disrupted gap junctions, increased endothelial permeability, and impaired EC migration. Silencing these enzymes involved in de novo ceramide biosynthesis in pulmonary macrophages could block this metabolic communication between macrophages and ECs mediated by EV-delivered ceramides, protecting EC function from CS exposure. When intratracheally administered to CS-exposed mice, these ceramide-rich macrophage-derived EVs exacerbated COPD by facilitating endothelial barrier disruption.
Conclusion: Our study uncovered a novel mechanism in COPD pathogenesis, where pulmonary macrophages propagate CS-induced metabolic stress to ECs via ceramide-laden EVs, leading to endothelial barrier dysfunction. This intercellular pathway represents a potential target for therapeutic intervention in COPD.
Keywords: COPD; Ceramide; Endothelial cells; Extracellular vesicles; Immunometabolism; Macrophages.
Chronic obstructive pulmonary disease (COPD) is a condition caused by damage to the airways or other parts of the lung and is often triggered by smoking. This damage triggers inflammation and other changes that block airflow and make breathing difficult. While we know that ceramides, a type of fat molecule, can harm cells inside the lungs, it was unclear how they might affect different cells in the body. In this study, we explored how ceramides move between cells and how they might contribute to COPD. We found that cigarette smoke increases ceramide production in a type of lung immune cells called macrophages. These ceramides are then packaged into tiny particles called extracellular vesicles and released from macrophages, which travel to other cells, especially cells lining the blood vessels (endothelial cells). Upon entering endothelial cells, these ceramides disrupt the function of endothelial cells, making the lung’s blood vessels more leaky and damaging their ability to repair. This process worsens the condition of COPD. Our study suggests that ceramides could be a new target for treating COPD by blocking this harmful communication between cells.
© 2025. The Author(s).