Microphysiological Models of Lung Epithelium-Alveolar Macrophage Co-Cultures to Study Chronic Lung Disease

A next-generation system for smoke inhalation integrated with a breathing lung-on-chip to model human lung responses to cigarette exposure

Continuous exposure to cigarette smoke (CS) significantly contributes to the development and progression of chronic obstructive pulmonary disease (COPD) and lung cancer. Animal models that inhale smoke nasally and have different lung physiology from humans may not accurately replicate cigarette smoke-induced health effects. Furthermore, traditional in vitro models fail to replicate the lung's dynamic mechanical forces and realistic inhalation exposure patterns, limiting their relevance in preclinical research. Here, we introduce an advanced smoke inhalation-based lung-on-chip system, the Continuous Flow AX12 (CFAX12), to investigate CS-induced cellular responses in a physiologically relevant manner. Unlike previous technologies, the CFAX12 integrates cyclic mechanical stretch with controlled whole-smoke exposure, allowing for a more accurate recreation of CS-induced alveolar microenvironment dynamics and barrier integrity responses. Using human alveolar epithelial cells, lung microvascular endothelial cells, and macrophages in mono- and co-culture models under air-liquid interface (ALI) conditions with breathing-like stretch (Str), we simulated key lung microenvironment features. Our results show that CS exposure using the CFAX12 induced a ~ 60% reduction in trans-barrier electrical resistance (TER), increased ROS generation depending on cellular model complexity, and a ~ 4.5-fold increase in IL-8 gene expression, all key hallmarks of early COPD pathogenesis. These findings underscore smoke-induced epithelial damage, inflammation, and oxidative stress, all of which contribute to alveolar barrier dysfunction and disease progression. Also, CFAX12 provides a more physiologically relevant alternative to submerged cigarette smoke extract (CSE) treatments, offering controlled whole-smoke exposure using the VC10 Smoking Robot, ensuring precisely regulated smoke delivery. Additionally, inclusion of pulmonary surfactant reduced IL8 gene levels by ~ 5 folds. Hence, by integrating mechanical and biological complexity, CFAX12 offers a robust platform for assessing inhaled smoke effects and identifying therapeutic targets. It's application in COPD drug screening can facilitate the discovery of compounds that preserve alveolar integrity, reduce inflammation, and mitigate oxidative damage, ultimately bridging the gap between regulatory and preclinical research applications.

Unravelling approaches to study macrophages: from classical to novel biophysical methodologies

Macrophages play crucial roles in immune responses and tissue homeostasis. Despite the fact that macrophages were described more than a century ago, they continue to be the cells of intensive interest. Advanced understanding of phenotypic diversity in macrophages holds great promise for development of cell-based therapeutic strategies. The introduction of innovative approaches in cell biology greatly enhances our ability to investigate the unique characteristics of macrophages. The review considers both classical methods to study macrophages and high-tech approaches, including single-cell sequencing, single-cell mass spectrometry, droplet microfluidics, scanning probe microscopy and atomic force spectroscopy. This review will be valuable both to specialists beginning their study of macrophages and to experienced scientists seeking to deepen their understanding of methods at the intersection of biological and physical sciences.

Precision cut lung slices: an integrated ex vivo model for studying lung physiology, pharmacology, disease pathogenesis and drug discovery

Precision Cut Lung Slices (PCLS) have emerged as a sophisticated and physiologically relevant ex vivo model for studying the intricacies of lung diseases, including fibrosis, injury, repair, and host defense mechanisms. This innovative methodology presents a unique opportunity to bridge the gap between traditional in vitro cell cultures and in vivo animal models, offering researchers a more accurate representation of the intricate microenvironment of the lung. PCLS require the precise sectioning of lung tissue to maintain its structural and functional integrity. These thin slices serve as invaluable tools for various research endeavors, particularly in the realm of airway diseases. By providing a controlled microenvironment, precision-cut lung slices empower researchers to dissect and comprehend the multifaceted interactions and responses within lung tissue, thereby advancing our understanding of pulmonary pathophysiology.

Epigenetic Reprogramming Drives Epithelial Disruption in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) remains a major public health challenge that contributes greatly to mortality and morbidity worldwide. Although it has long been recognized that the epithelium is altered in COPD, there has been little focus on targeting it to modify the disease course. Therefore, mechanisms that disrupt epithelial cell function in patients with COPD are poorly understood. In this study, we sought to determine whether epigenetic reprogramming of the cell-cell adhesion molecule E-cadherin, encoded by the CDH1 gene, disrupts epithelial integrity. By reducing these epigenetic marks, we can restore epithelial integrity and rescue alveolar airspace destruction. We used differentiated normal and COPD-derived primary human airway epithelial cells, genetically manipulated mouse tracheal epithelial cells, and mouse and human precision-cut lung slices to assess the effects of epigenetic reprogramming. We show that the loss of CDH1 in COPD is due to increased DNA methylation site at the CDH1 enhancer D through the downregulation of the ten-eleven translocase methylcytosine dioxygenase (TET) enzyme TET1. Increased DNA methylation at the enhancer D region decreases the enrichment of RNA polymerase II binding. Remarkably, treatment of human precision-cut slices derived from patients with COPD with the DNA demethylation agent 5-aza-2'-deoxycytidine decreased cell damage and reduced air space enlargement in the diseased tissue. Here, we present a novel mechanism that targets epigenetic modifications to reverse the tissue remodeling in human COPD lungs and serves as a proof of concept for developing a disease-modifying target.