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. Pediatr. Pulmonol. 2011; 46:927–933. © 2011 Wiley‐Liss, Inc.