Tri-culture model of intestinal epithelial cell, macrophage, and bacteria for the triggering of inflammatory bowel disease on a microfluidic device

Inflammatory bowel disease (IBD) involves gastrointestinal inflammation, due to intestinal epithelial barrier destruction caused by excessive immune activation. Conventional cell culture systems do not provide a model system that can recapitulate the complex interactions between epithelial cells, immune cells, and intestinal bacteria. To address this, we developed a microfluidic device that mimics the inflammatory response associated with microbial invasion of the intestinal mucosa. The device consisted of two media channels, an upper and a lower channel, and a porous membrane between these channels on which C2BBe1 intestinal epithelial cells were seeded to form a tight junction layer. Each electrode was placed in contact with both channels to continuously monitor the tight junction state. Fresh medium flow allowed bacterial numbers to be controlled and bacterial toxins to be removed, allowing co-culture of mammalian cells and bacteria. In addition, RAW264 macrophage cells were attached to the bottom of the lower channel. By introducing E. coli into the lower channel, the RAW264 cells were activated and produced TNF-α, successfully recapitulating a culture model of inflammation in which the C2BBe1cell tight junction layer was destroyed. The main structure of the device was initially made of polydimethylsiloxane to facilitate its widespread use, but with a view to introducing anaerobic bacteria in the future, a similar phenomenon was successfully reproduced using polystyrene. When TPCA-1, an IκB kinase 2 inhibitor was added into this IBD culture model, the tight junction destruction was significantly suppressed. The results suggest that this IBD culture model also is useful as a screening system for anti-IBD drugs.