Milk-CLA is a biomarker for traditional farm milk but is not responsible for the allegro-protective farm milk effect in a murine model of airway inflammation

Cross-sectional epidemiological studies have demonstrated that farm milk from traditional farm settings in alpine regions and different rural non-alpine regions possesses allergo-protective properties. We aimed to elucidate possible biomarkers characteristic for farm milk by comparing farm and dairy milk samples collected with the “Protection against Allergy Study in Rural Environments (PASTURE)/Mechanisms of early life protection against allergy (EFRAIM)-Study” for their fatty acid pattern. In addition, we aimed to analyze possible candidates for their allegro-protective capacities in an experimental approach. Therefore, milk fatty acid content in cow's milk and murine sera were determined by using gas chromatography. We used female Balb/C mice in a model of acute airway inflammation and determined whether diets enriched with spray-dried farm milk powder rich in CLA attenuate the allergic lung inflammation. CLA might be a biomarker for farm milk that harbors allegro-protective properties. Feeding animals with a diet enriched with spray-dried farm milk powder milk rich in CLA did increase the CLA content in plasma, erythrocyte membranes and phospholipids, indicating bioavailability of milk fatty acids incorporated into the diet. Nevertheless, this application did not reduce the leukocyte infiltration, airway inflammation, airway hyper-responsiveness (AHR) or the concentration of lipid mediators in bronchoalveolar lavage (BAL) in sensitized and challenge mice compared to mice fed CLA-free diet. Taken together, our data indicate that CLA might act as a biomarker for allegro-protective farm milk but is not involved in the allegro-protective effect of farm milk.