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 host intestinal epithelial cells remains
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 epithelial cells underwent spontaneous
3D morphogenesis into spheroid-like structures with diameters ranging
from 50 to 100 μm. Functional assays revealed that the C. jejuni secretome and EVs (multiplicity of infection,
MOI 10) caused a 60% reduction in Caco-2 cell viability in 2D plate
cultures, as measured by the MTT assay. In contrast, 3D Caco-2 spheroids
showed significantly increased resistance to cytotoxic effects of
secreted virulence factors of C. jejuni. By combining impedance spectroscopy and live microscopic observation,
the platform allowed real-time monitoring of cellular spatial growth
and sensitive detection of EV interactions with intestinal epithelial
cells, highlighting the protective role of 3D cell organization. The
physiological relevance of the model was confirmed by TEER measurements
that suggested that Campylobacter EVs
diffused 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.