Modeling of Ligand-Induced Acute and Chronic Inflammation in the gastrointestinal tract using In vitro 3D-human small intestinal microtissues

Intestinal epithelium is known to be involved in innate immune responses by recognizing potential pathogens through cellular pattern recognition receptors (PRRs). The purpose of this study is to investigate PRR responses following exposure of an in vitro 3D human small intestinal (SMI) microtissue to various Toll-like receptor (TLRs) and Node-like receptor (NOD) ligands. The SMI microtissues are cultured using human intestinal fibroblasts and enterocytes and their 3-dimensional polarity and morphology mimics that of native in vivo tissues. Characterization of the microtissues included evaluation of structural features, barrier properties, and expression of drug transporters and drug metabolizing enzymes. Results showed that exposure of intestinal microtissues to live bacterial or ligands to TLR4 (LPS) and NOD2 (Muramyl dipeptide; MDP) were able to induce gene expression of proinflammatory cytokines such as IL-1β, IL-6, and RANTES. Prolonged exposure of intestinal microtissues to IL-1β also resulted in reduced membrane integrity and induction of pro-inflammatory cytokines (IL-6 and CCL20) known to stimulate acquired immune cell responses by inducing cytokine release such as TNF-α and IFN- or by initiating the migration of inflammatory cells. All these responses may be precursors for IBD-like disease. To simulate the effect of immune cell responses on the intestinal epithelium, we also exposed the microtissues to TNF-α and IFN-, which resulted in the reduction of membrane integrity and the release of proinflammatory cytokines. The effect of TNF-α and IFN- on the intestinal epithelium was further exacerbated if antigen-presenting cells such as dendritic cells were incorporated into the 3D intestinal microtissues. In summary, our results suggest that the EpiIntestinal tissue is capable of modeling innate immune responses and can be a useful tool to study the complex interactions of human intestinal epithelium with microbiome in vitro in the induction IBD-like disease.

EpiIntestinal (SMI-100, SMI-100-FT), Intestinal-dendritic cell coculture, Innate immune defense, Inflammation, Toll-like receptor (TLR), Node-like receptor (NOD) ligands, TLR4, NOD2, Muramyl dipeptide, MDP, IL-1b, IL-6, RANTES, CCL20, GRO-a, LP-10, TEER

LPS, L18-MDP, TNF-a, IFN-g, IL-17a