Cis-9, trans-11-conjugated linoleic acid inhibits allergic sensitization and airway inflammation via a PPARγ-related mechanism in mice

Abstract

Milk consumption from early childhood on has been found to be inversely correlated with allergic sensitization and the onset of bronchial asthma. We tested whether cis-9,trans-11-conjugated linoleic acid (c9,t11-CLA), naturally occurring in milk fat, may prevent allergic sensitization and inhibit airway inflammation in a murine asthma model. BALB/c mice were fed a diet enriched in 1 wt% of c9,t11-CLA or a control diet 7 d prior to and for 32 d during sensitization [d 1 and 14,100mg/L ovalbumin (OVA) in adjuvant vs. PBS] and airway challenges (d 28-30,1% OVA in PBS vs. PBS). Subgroups of mice were coadministered 20 μmol/L of the selective PPARγ antagonist GW9662 during each OVA challenge. C9,t11-CLA feeding resulted in significantly reduced IgE production and allergen-induced in vivo airway hyperresponsiveness. Further, less mucous plugging of segmental bronchi and significantly reduced interleukin-5 and eosinophils were determined in bronchoalveolar lavage fluids of c9,t11-CLA-fed mice. C9,t11-CLA feeding prevented the downregulation of PPARγ mRNA in the lung tissues observed after allergen sensitization and airway challenges in control mice. The inhibitory effects of c9,t11-CLA on airway inflammation were partially prevented by coadministration of GW9962. Further, c9,t11-CLA feeding resulted in a significantly lower concentration of the eicosanoid precursor, arachidonic acid, in tissue lipids. These findings demonstrate that dietary c9,t11-CLA can reduce allergic airway inflammation, most likely via a PPARγ-related mechanism and by reducing eicosanoid precursors. They give new insights into the fatty acid-mediated mechanism of immunomodulation and may represent a step toward an attractive novel strategy in the dietary prevention and treatment of allergic asthma. © 2008 American Society for Nutrition.