This controlling effect of IBD fibroblasts on barrier function when combined with healthy epithelium was also accompanied by increased production of multiple inflammatory cytokines and chemokines including IL-6, MCP-1 (Fig. 4B), IL-8, CXCL-1, LIF, IL-21, PIGF-1, and MIP-1b (Extended Data Fig. 10A) relative to chips lined by healthy fibroblasts and epithelium or healthy epithelium alone. Here, IL21 is linked to inflammatory bowel disease.