Background
Gastric aspiration is a significant cause of acute lung injury and acute respiratory distress syndrome. Environmental risk factors, such as a diet high in pro-inflammatory advanced glycation end-products (AGEs), may render some patients more susceptible to lung injury after aspiration. We hypothesized that high dietary AGEs increase its pulmonary receptor, RAGE, producing an amplified pulmonary inflammatory response in the presence of high mobility group box 1 (HMGB1), a RAGE ligand and an endogenous signal of epithelial cell injury after aspiration.
Materials and Methods
CD-1 mice were fed either a low AGE (LAGE) or high AGE (HAGE) diet for 4 weeks. After aspiration injury with acidified small gastric particles, bronchial alveolar lavage (BAL) and whole-lung tissue samples were collected at 5 minutes, 1 hour, 5 hours, and 24 hours post-injury. RAGE, soluble RAGE (sRAGE), HMGB1, cytokine and chemokine concentrations, albumin levels, neutrophil influx, and lung myeloperoxidase (MPO) activity were measured.
Results
We observed that HAGE-fed mice exhibited greater pulmonary RAGE levels before aspiration and increased BAL sRAGE levels after aspiration compared to LAGE-fed mice. Lavage HMGB1 levels rose immediately after aspiration, peaking at 1 hour, and strongly correlated with sRAGE levels in both dietary groups. HAGE-fed mice demonstrated higher cytokine and chemokine levels with increased pulmonary MPO activity over 24 hours versus LAGE-fed mice.
Conclusions
This study indicates that high dietary AGEs can increase pulmonary RAGE, augmenting the inflammatory response to aspiration in the presence of endogenous damage signals such as HMGB1.