Effects of infant formula on cell homeostasis and cytokine levels in an in vivo and in vitro murine aspiration model.

Rationale: The role of infant formula aspiration in lung injury has not been studied extensively. We evaluated the effects of a single infant formula aspiration into the lungs of mice and the effect of infant formula exposure on cell lines representing murine alveolar macrophages and type II epithelial cells.
Objectives: To study the effects of exposure to infant formula on cell count histology and cytokine levels in an in vivo and in vitro model of aspiration.
Methods: In vivo: Juvenile mice received 2.5 µl/g of 50% infant formula intranasally. Bronchoalveolar lavage samples were collected at 1, 2, and 7 days after aspiration and evaluated for cell count and differential. In vitro: RAW 264.7 and MLE-15 cells were exposed to 1% infant formula for 6 hr. Extracellular levels of IL-6, TNF-α, MIP-2, and KC were measured in lavage fluid and cell media using ELISA assays.
Results: In vivo: An increase in neutrophils, IL-6 and KC levels were noted 24 hr after infant formula exposure. In vitro: An increase in TNF-α levels from RAW 264.7 and MIP-2 and KC levels from MLE-15 cells was noted after infant formula exposure.
Conclusions: A single aspiration of infant formula into the lungs leads to an acute inflammatory response involving both lung macrophages and epithelial cells.
(Copyright © 2011 Wiley-Liss, Inc.)