Development of an in vitro co-culture model to mimic the human intestine in healthy and diseased state

TLDR

The intestine is the largest interface between the environment and the human body, and its integrity is essential for nutrient uptake while preventing harmful antigens, but inflammatory conditions can markedly alter its normal function. The authors aim to develop an in‑vitro co‑culture model that reproduces both healthy and inflamed intestinal tissue to study inflammation mechanisms and test new therapeutics. They established a co‑culture of Caco‑2 epithelial cells and PMA‑differentiated THP‑1 macrophages, priming the barrier with IFN‑γ and the macrophages with LPS/IFN‑γ to simulate healthy and controlled inflamed states. Under homeostatic conditions the co‑culture maintained barrier integrity and showed no cytokine, nitric oxide or LDH release, whereas the inflamed setup caused a temporary barrier breakdown and elevated pro‑inflammatory cytokines and cytotoxicity markers, demonstrating the model’s capacity to recapitulate key hallmarks of intestinal inflammation.

Abstract

The intestine forms the largest interface between the environment and the human organism. Its integrity and functioning are crucial for the uptake of nutrients while preventing access of harmful antigens. Inflammatory conditions can significantly change the normal functioning of the intestine. In vitro models that adequately reproduce both healthy and inflamed intestinal tissue could provide a useful tool for studying the mechanisms of intestinal inflammation and investigating new therapeutic drugs. We established a co-culture of Caco-2 and PMA-differentiated THP-1 cells that mimics the intestine in healthy and controlled inflamed states. In homoeostatic conditions without stimulation, Caco-2 and THP-1 cells were co-cultured for 48 h without affecting the barrier integrity and with no increase in the release of cytokines, nitric oxide or lactate dehydrogenase. To simulate the inflamed intestine, the Caco-2 barrier was primed with IFN-γ and THP-1 cells were pre-stimulated with LPS and IFN-γ. In these conditions a significant but temporary reduction in barrier integrity was measured, and large concentrations of pro-inflammatory cytokines and cytotoxicity markers detected. With its ability to feature numerous hallmarks of intestinal inflammation the presented co-culture model of epithelial cells and macrophages offers a unique possibility to study exposure effects in relation to the health status of the intestine.