Abstract
To further the development of a model for simultaneously assessing intestinal absorption and first-pass metabolism in vitro, Caco-2, LS180, T84 and SIEC cells were cultured on permeable inserts and the integrity of cell monolayers, CYP3A4 activity and the inducibility of enzymes and transporters involved intestinal drug disposition were measured. Caco-2, T84 and SIEC cells all formed tight junctions, as assessed by immunofluorescence microscopy for zonula occludens-1 (ZO-1), which was well organized into circumscribing strands in SIEC, T84 and Caco-2 cells, but was diffuse in LS180 cells. The TEER value for LS180 monolayers was lower than that for Caco-2, T84 and SIEC. In addition, the apical-to-basolateral permeability of the paracellular marker, lucifer yellow, across LS180 monolayers was higher than in SIEC, T84 and Caco-2 monolayers. The transcellular marker, propranolol exhibited similar permeability across all cells. With regard to metabolic capacity, T84 cells and LS180 cells showed comparable basal midazolam hydroxylation activity and it was inducible by rifampin and 1α,25(OH)2D3 in LS180 cells, but only marginally so in T84 cells. The basal CYP3A4 activity of SIEC and Caco-2 cells was much lower and not inducible. Interestingly, some of the drug transporters expressed in LS180 cells and Caco-2 cells were induced by either 1α,25(OH)2D3 or rifampin or both, but there were only limited effects in the other two cell lines. These results suggest that none of the cell lines tested fully replicated the drug disposition properties of the small intestine and that the search for an ideal screening tool must continue.
- The American Society for Pharmacology and Experimental Therapeutics