Allergic Response Modulation by Phytosterols in a Murine Model of Pollen Allergy

RATIONALE: Phytosterols are sterol molecules synthesized by plants. Some of them have been shown to exhibit anti-inflammatory, anti-neoplastic, anti-pyretic, and immune-modulating activities. A preliminary study was carried out to characterize the effect of a phytosterol mixture on the systemic allergen-induced responses and airway reactivity in a murine model of allergic airway inflammation. METHODS: Female BALB/c mice were sensitized by three subcutaneous injection of olive pollen extract (Olea europaea). One week after last dose different groups were treated with a phytosterol mixture either alone or in combination with a lipid emulsion. A healthy mice control group and an olive-sensitized mice treated with saline were also included. Allergic airway response was induced by intranasal instillation of Olea. The Olea-specific immunoglobulin response in serum, the splenocyte cytokine production and the bronchial hyper-responsiveness to methacholine was compared at several time-points. RESULTS: All olea-sensitized mice developed a specific allergen IgG1 response. A significant increase in IgG2a production was observed in the mice injected with a phytosterol mixture. Th2 cytokines released in the active treated group was reduced (IL-4 and IL-13) from cultured splenocytes. Airway reactivity to methacholine was partially reversed in the mice treated with phytosterols. CONCLUSIONS: The administration of phytosterols downregulate the allergic response and reduce bronchial hyper-responsiveness. The use of these molecules could provide a new tool for future treatment of allergic diseases.