Assessing Campylobacter jejuni Extracellular Vesicle-Host Interaction Using a Microfluidic Platform with Caco-2 Spheroides-on-Chip

Campylobacter jejuni is a foodborne pathogen that adheres to and invades the epithelial cells of the human intestinal tract. The extracellular vesicles (EVs) of C. jejuni have an important impact during pathogenicity but their role in invasion of the host intestinal epithelial cells remain largely unknown. In vitro models lack the complexity of tissue and fail to accurately replicate the dynamic interactions between EVs and human intestinal epithelial cells, while animal infection models have species-specific differences that limit their translational relevance and are associated with ethical concerns. To bridge this gap, we propose a microfluidic platform integrated with an impedimetric sensor to monitor C. jejuni EV interactions with human intestinal epithelial Caco-2 cells. When cultured in this microfluidic device, Caco-2 cells underwent spontaneous 3D morphogenesis and were spatially organised into spheroid-like structures. By combining impedance spectroscopy and microscopic observation, the platform allowed direct monitoring of cellular spatial growth and sensitive detection of their interaction with EVs. Although functional assays revealed that the C. jejuni EVs killed Caco-2 cells cultured on plates, 3D Caco-2 spheroids showed significantly greater resistance to both C. jejuni secretome and EVs. The physiological relevance of the model was confirmed by TEER measurements that suggested that Campylobacter EVs difused paracellularly. The developed microfluidic device is a promising platform for investigating host‒microbe interactions and may have a broad impact on biomedical research on gastroenteritis.