Lactoferrin protects against intestinal inflammation and bacteria-induced barrier dysfunction in vitro

The iron-binding glycoprotein lactoferrin (LF) is naturally present in human breast milk. Several studies suggest that LF contributes to infant health and development owing to a variety of protective effects, including antimicrobial and anti-inflammatory features. Therefore, we aimed to elucidate its protective properties on intestinal epithelial barrier dysfunction induced by infection or inflammation using the human epithelial cell culture models HT-29/B6 and T84. During barrier perturbation induced by the proinflammatory cytokine tumor necrosis factor α (TNF-α), bovine LF restored tight junction (TJ) morphometry and inhibited TNF-α-induced epithelial apoptosis. This resulted in an attenuation of the TNF-α-induced decrease in transepithelial resistance (TER) and increases in permeability of fluorescein and FITC-dextran (4 kDa) and was as effective as the apoptosis inhibitor Q-VD-Oph. The enteropathogenic bacterium Yersinia enterocolitica is a frequent cause of diarrhea in early childhood. This involves focal changes in TJ protein expression and localization. LF diminished the Y. enterocolitica-induced drop in TER in the present in vitro model, which was paralleled by an inhibition of the Yersinia-induced reduction of claudin-8 expression via c-Jun kinase signaling. In conclusion, LF exerts protective effects against inflammation- or infection-induced barrier dysfunction in human intestinal cell lines, supporting its relevance for healthy infant development.