Development of an in vitro co-culture model using Caco-2 and J774A.1 cells to mimic intestinal inflammation

In vitro models that mimic the pathophysiology in vivo are important tools to study mechanisms of disease and assess the pharmacology and toxicity of drugs. In this work, we report the development of a novel model of intestinal inflammation. This model is based on the co-culture of intestinal epithelial Caco-2 cells and murine J774A.1 macrophages. The model is shown to mimic the intestinal barrier in both healthy and inflamed state. In the healthy state, without external stimulation, Caco-2 and J774A.1 cells were co-cultured in one system without affecting the barrier integrity of intestinal epithelial cells and without inducing release of cytokines from macrophages. To mimic the inflamed intestine, Caco-2 cells were primed with an optimised cytokine cocktail (TNF-⍺, IFN-γ and IL-1β) and J774A.1 cells were pre-exposed to lipopolysaccharide (LPS) and IFN-γ for 24 h before combining the two cell lines into co-culture. In these conditions, a significant disruption of the epithelial barrier and an increase in pro-inflammatory cytokine (TNF-⍺ and IL-6) levels released from macrophages were detected. The data also show that inflammation in the co-culture model was temporary and reversible upon the removal of the inflammatory stimulus. This new in vitro model could be a valuable tool for investigating the safety and efficacy of drugs in the context of intestinal inflammation and provides advantages over other reported co-culture models of intestinal inflammation in terms of cost and simplicity.