CD28 and inflammatory bowel disease: This and similar models, which mimic the gut epithelium/immune cell interface, are useful in the search for drugs or food substances that can be used to treat or prevent IBD-like symptoms [36], for instance, butyrate has been shown to protect against barrier disruption in a Caco-2/PBMCs co-culture model with lipopolysaccharide- (LPS) and anti-CD3/CD28-activated PBMCs [37].