Hookworm infection induces the expression of TFF2, which limits hemorrhagic lung injury but promotes fibrosis and airway hyperresponsiveness. (A) Time course evaluation of TFF2 mRNA transcript levels in lung and jejunum of N. brasiliensis–infected WT C57BL/6 mice. Means ± SE of five to six mice/group are shown. (B) Masson’s Trichrome staining for collagen (green) on paraffin-embedded lung tissues of naive mice or after infection with 500 N. brasiliensis larvae at the indicated time points. Erythrocytes stain crimson red. Representative images are shown. (C) Numbers of erythrocytes in the BAL fluid of WT versus TFF2^−/− mice infected with 500 N. brasiliensis larvae at the indicated time points. Means ± SE of five to six mice/group are shown. Data are representative of two to three independent experiments (*, P < 0.05; **, P < 0.01). (D) Masson’s Trichrome staining for collagen (green) on paraffin-embedded lung tissues of WT and TFF2^−/− mice on day 28 after infection with 500 N. brasiliensis larvae. Representative images are shown. (E) Hydroxyproline content of lung tissue at day 28 after infection. Each point represents an individual lobe of lung. The dotted line indicates the level of hydroxyproline in naive WT mouse lung (*, P < 0.05). Horizontal bars indicate the mean. Data are representative of two independent experiments. Bars, 100 µm.