Lung levels of phosphorylated ERK1/2, p38 MAPK and JNK 1/2/3.

<p>C57/Bl6 and IL-17R^−/− mice were exposed to air or to ozone. Data shown as mean ± SEM for n = 5 in each group; *p<0.05 compared to air in the same species; ^#p<0.05 compared to C57/Bl6 mice with corresponding exposure. RFU: Relative fluorescence unit.</p

Acetylcholine (ACh)-induced isometric bronchial contractile tension.

<p>Air- and ozone-exposed C57/BL6 mice (6 in air- and 9 in ozone-exposed) and IL17RA^−/− mice (6 in air- and 5 in ozone-exposed) were studied. Data expressed as mean ±S.E.M. *p<0.05, **p<0.01, ***p<0.001, compared with air-exposed mice.</p

Effect of dexamethasone (10⁻⁶ M) on acetylcholine (ACh)-induced bronchial contractile responses.

<p>Air-exposed C57/BL6 mice (n = 6; Panel A) and IL-17R^−/− mice (n = 6; Panel B) and ozone-exposed C57/BL6 mice (n = 9; Panel C) and IL-17R^−/− mice (n = 6; Panel D) were studied. Under each condition, the effect of dexamethasone has been compared to responses in the absence of this inhibitor. Data presented as mean±SEM. *p<0.05 compared with dexamethasone-treated tissues.</p

Levels of lung IL-17, IL-1β and TNFα.

<p>C57/Bl6 and IL-17R^−/− mice were exposed to air or to ozone. Data shown as mean ± SEM for n = 5 in each group; *p<0.05 compared to air in the same species; ^#p<0.05 compared to C57/Bl6 mice with corresponding exposure.</p

image_2_Interleukin-1α Mediates Ozone-Induced Myeloid Differentiation Factor-88-Dependent Epithelial Tissue Injury and Inflammation.tiff

<p>Air pollution associated with ozone exposure represents a major inducer of respiratory disease in man. In mice, a single ozone exposure causes lung injury with disruption of the respiratory barrier and inflammation. We investigated the role of interleukin-1 (IL-1)-associated cytokines upon a single ozone exposure (1 ppm for 1 h) using IL-1α-, IL-1β-, and IL-18-deficient mice or an anti-IL-1α neutralizing antibody underlying the rapid epithelial cell death. Here, we demonstrate the release of the alarmin IL-1α after ozone exposure and that the acute respiratory barrier injury and inflammation and airway hyperreactivity are IL-1α-dependent. IL-1α signaling via IL-1R1 depends on the adaptor protein myeloid differentiation factor-88 (MyD88). Importantly, epithelial cell signaling is critical, since deletion of MyD88 in lung type I alveolar epithelial cells reduced ozone-induced inflammation. In addition, intratracheal injection of recombinant rmIL-1α in MyD88^acid mice led to reduction of inflammation in comparison with wild type mice treated with rmIL-1α. Therefore, a major part of inflammation is mediated by IL-1α signaling in epithelial cells. In conclusion, the alarmin IL-1α released upon ozone-induced tissue damage and inflammation is mediated by MyD88 signaling in epithelial cells. Therefore, IL-1α may represent a therapeutic target to attenuate ozone-induced lung inflammation and hyperreactivity.</p

Inflammation score in the airways and lungs of air- and ozone-exposed mice.

<p>Compared with air exposed control mice, the inflammation score was increased significantly in ozone exposed C57/BL6 mice but not in IL-17R^−/−mice. Data are expressed as means ± SEM. *p<0.01.</p

image_1_Interleukin-1α Mediates Ozone-Induced Myeloid Differentiation Factor-88-Dependent Epithelial Tissue Injury and Inflammation.tiff

<p>Air pollution associated with ozone exposure represents a major inducer of respiratory disease in man. In mice, a single ozone exposure causes lung injury with disruption of the respiratory barrier and inflammation. We investigated the role of interleukin-1 (IL-1)-associated cytokines upon a single ozone exposure (1 ppm for 1 h) using IL-1α-, IL-1β-, and IL-18-deficient mice or an anti-IL-1α neutralizing antibody underlying the rapid epithelial cell death. Here, we demonstrate the release of the alarmin IL-1α after ozone exposure and that the acute respiratory barrier injury and inflammation and airway hyperreactivity are IL-1α-dependent. IL-1α signaling via IL-1R1 depends on the adaptor protein myeloid differentiation factor-88 (MyD88). Importantly, epithelial cell signaling is critical, since deletion of MyD88 in lung type I alveolar epithelial cells reduced ozone-induced inflammation. In addition, intratracheal injection of recombinant rmIL-1α in MyD88^acid mice led to reduction of inflammation in comparison with wild type mice treated with rmIL-1α. Therefore, a major part of inflammation is mediated by IL-1α signaling in epithelial cells. In conclusion, the alarmin IL-1α released upon ozone-induced tissue damage and inflammation is mediated by MyD88 signaling in epithelial cells. Therefore, IL-1α may represent a therapeutic target to attenuate ozone-induced lung inflammation and hyperreactivity.</p

Mean linear intercept (L_m) in the lungs of air- and ozone exposed mice (Panel A).

<p>Lungs inflated at 25 cm of water were sectioned and stained with haematoxylin and eosin and microscopically assessed for L_m. Ozone exposed C57/BL6 mice and IL-17R^−/− mice showed increased Lm (alveolar enlargement) compared with their appropriate air-exposed control mice. Emphysema score in the lungs of air- and ozone exposed mice (Panel B). Compared with air exposed mice, the emphysema score was increased in ozone-exposed C57/BL6 and IL-17R^−/−mice, while it was increased further in ozoneexposed IL-17R^−/− mice. Data are expressed as means ± SEM. *p<0.05; <b>*</b>*p<0.01; ***p<0.001. Representative histological sections of mouse lungs (Panel C i, ii, iii & iv). Lung sections were stained with haematoxylin and eosin after 6 weeks of exposure to ozone showing enlargement of alveolar spaces in C57/BL6 (Panel C ii) and IL-17A^−/− mice (Panel C iv).</p

Effect of SB239063 (10⁻⁶ M) on acetylcholine (ACh)-induced bronchial contractile responses.

<p>Air-exposed C57/BL6 mice (n = 6; Panel A) and IL-17R^−/− mice (n = 6; Panel B) and ozone-exposed C57/BL6 mice (n = 9; Panel C) and IL-17R^−/− mice (n = 6; Panel D) were studied. Under each condition, the effect of SB239063 has been compared to responses in the absence of this inhibitor. Data presented as mean±SEM. *p<0.05; **p<0.01 compared with SB239063-treated tissues.</p

Concentration-response curves to acetylcholine (ACh) and –log provocative concentration of ACh required to increase lung resistance (R_L) by 100% from baseline (PC₁₀₀).

<p>C57/BL6 and IL-17R^−/− mice were exposed to air or to ozone. Data is expressed as mean ± S.E.M. **p<0.01; ***p<0.001, compared with to air-exposed mice.</p