ARS | Publication request: Different responses of Fe transporters in Caco2/HT29-MTX cocultures than in independent Caco-2 cell cultures

Submitted to: Cell Biology International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2009
Publication Date: September 1, 2009
Citation: Laparra, J., Glahn, R.P., Miller, D. 2009. Different responses of Fe transporters in Caco2/HT29-MTX cocultures than in independent Caco-2 cell cultures. Cell Biology International. 33(9):971-977.

Interpretive Summary: A model for assessing Fe bioavailability has been developed in our lab, which uses a simulated digestion and Caco-2 epithelial tissue cell culture. Caco-2 cell differentiate into enterocytes-like cells, thus imitate the intestinal lining and is useful to evaluate absorption of minerals into our bodies. However, the human intestinal epithelium is composed of several cell types; mainly enterocytes and globet (mucin-secreting) cells. We used the HT29-MTX cell line which produces a mucus layer over the Caco-2 intestinal cells to more closely imitate the conditions in the body. The Caco-2 cells and Caco-2/HT29-MTX co-cultures, at ratios 75:25, showed similar iron uptake when exposed to iron and iron/ascorbic acid solutions. However, in Caco-2/HT29-MTX co-cultures a different regulation pattern in the transporters involved on Fe absorption was noted compared to Caco-2 cell cultures. In addition, iron uptake from foods was much lower in the Caco-2/HT29-MTX co-cultures than independent Caco-2 cultures. Further research needs to be done to characterize the Caco-2/HT29-MTX co-culture system to see if the co-culture model can be used to accurately predict iron uptake.

Technical Abstract: The human intestinal epithelium is composed of several cell types; mainly enterocytes and globet (mucin-secreting) cells. This study compares the cellular response for Fe transporters in Caco-2, HT29-MTX, and Caco-2/HT29-MTX coculture models for Fe bioavailability studies. Under culture, Caco-2 cells differentiate into enterocytes-like cells and HT29-MTX cell lineage into a mucin secreting cellular population. Cell cultures were exposed to digests of Fe+3, Fe+3/ascorbic acid, cooked fish (high-available Fe) or white beans (low-available Fe). The cell responses in mRNA expression of the main Fe transporters, DMT1 and Dcytb, and cell ferritin formation were monitored. In Caco-2/HT29-MTX cocultures, mucin layer lowered the pool of free Fe to diffuse towards the cell brush border membrane of enterocytes accompanied of an up-regulation of DMT1 mRNA expression. In contrast, cultures exposed to digests of fish or white beans showed no significant differences in Fe transporters regulation.