Figure 2. EP2-deficient mice are resistant to OVA-induced asthma.

EP2-deficient mice (KO) and the wild type littermates (WT) were sensitized and challenged with OVA as described in the materials and methods. Control animals received PBS only. Pathological analyses were performed two days after the last challenge. (A,B) Lung tissues were fixed, sectioned and stained with H&E to reveal lymphocyte infiltration (A) or with periodic acid-Schiff (PAS) to show mucus production (B). (C) BALF was collected and examined for the number of total inflammatory cells and eosinophils. (D) The airway hyperresponsiveness in the model animals was assessed by measuring resistance of respiratory system (Rrs) in response to increasing intravenous doses of methacholine chloride. This experiment was repeated three times with 4–6 mice for each group each time. Data are presented as mean ± SEM. *P < 0.05. **P < 0.01. ***P < 0.005.