Dietary flaxseed supplementation ameliorates inflammation and oxidative tissue damage in experimental models of acute lung injury in mice

Flaxseed (FS) is a nutritional supplement with high concentrations of (n-3) fatty acids and lignans that have anti-inflammatory and antioxidant properties. The use of FS in the prevention or treatment of acute lung disease is unknown. In this study, we evaluated diets with high FS content in experimental murine models of acute lung injury and inflammation. The kinetics of lignan accumulation in blood, following 10% FS supplementation, was determined using liquid chromatography tandem mass spectrometry. Mice were fed isocaloric control and 10% FS-supplemented diets for at least 3 wk and challenged by hyperoxia (80% oxygen), intratracheal instillation of lipopolysacharide, or acid aspiration. Bronchoalveolar lavage was evaluated for white blood cells, neutrophils, and proteins after a 24 h postintratracheal challenge of hydrochloric acid or lipopolysacharide, or after 6 d of hyperoxia. Lung lipid peroxidation was assessed by tissue malondialdehyde concentrations. The plasma concentrations of the FS lignans, enterodiol and enterolactone, were stable after mice had eaten the diets for 2 wk. Following hyperoxia and acid aspiration, bronchoalevolar lavage neutrophils decreased in FS-supplemented mice (P = 0.012 and P = 0.027, respectively), whereas overall alveolar white blood cell influx tended to be lower (P = 0.11). In contrast, neither lung injury nor inflammation was ameliorated by FS following lipopolysacharide instillation. Lung malondialdehyde levels were lower in hyperoxic mice than in unchallenged mice (P = 0.0001), and decreased with FS treatment following acid aspiration (P = 0.011). Dietary FS decreased lung inflammation and lipid peroxidation, suggesting a protective role against prooxidant-induced tissue damage in vivo.