Interleukin‐33 induces interleukin‐17<scp>F</scp> in bronchial epithelial cells

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p><jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 is clearly expressed in the airway of patients with asthma, but its role in asthma has not yet been fully understood. <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> is also involved in the pathogenesis of asthma. However, the regulatory mechanisms of <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> expression remain to be defined. To further indentify the role of <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 in asthma, we investigated the expression of <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> by <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 in bronchial epithelial cells and its signaling mechanisms.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Bronchial epithelial cells were stimulated with <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33. The levels of <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> expression were analyzed using real‐time <jats:styled-content style="fixed-case">PCR</jats:styled-content> and <jats:styled-content style="fixed-case">ELISA</jats:styled-content>. Next, the involvement of <jats:styled-content style="fixed-case">ST</jats:styled-content>2, <jats:styled-content style="fixed-case">MAP</jats:styled-content> kinases, and mitogen‐ and stress‐activated protein kinase1 (<jats:styled-content style="fixed-case">MSK</jats:styled-content>1) was determined by <jats:styled-content style="fixed-case">W</jats:styled-content>estern blot analyses. Various kinase inhibitors and anti‐<jats:styled-content style="fixed-case">ST</jats:styled-content>2 neutralizing <jats:styled-content style="fixed-case">A</jats:styled-content>bs were added to the culture to identify the key signaling events leading to the expression of <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content>, in conjunction with the use of short interfering <jats:styled-content style="fixed-case">RNA</jats:styled-content>s (si<jats:styled-content style="fixed-case">RNA</jats:styled-content>s) targeting <jats:styled-content style="fixed-case">MSK</jats:styled-content>1.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p><jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 significantly induced <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> gene and protein expression. The receptor for <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33, <jats:styled-content style="fixed-case">ST</jats:styled-content>2, was expressed in bronchial epithelial cells. Among <jats:styled-content style="fixed-case">MAP</jats:styled-content> kinases, <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 phosphorylated <jats:styled-content style="fixed-case">ERK</jats:styled-content>1/2, but not p38<jats:styled-content style="fixed-case">MAPK</jats:styled-content> and <jats:styled-content style="fixed-case">JNK</jats:styled-content>. It was inhibited by the pretreatment of anti‐<jats:styled-content style="fixed-case">ST</jats:styled-content>2 neutralizing (blocking) <jats:styled-content style="fixed-case">A</jats:styled-content>bs. <jats:styled-content style="fixed-case">MEK</jats:styled-content> inhibitor significantly blocked <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> production. Moreover, <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 phosphorylated <jats:styled-content style="fixed-case">MSK</jats:styled-content>1, and <jats:styled-content style="fixed-case">MEK</jats:styled-content> inhibitor diminished its phosphorylation. Finally, <jats:styled-content style="fixed-case">MSK</jats:styled-content>1 inhibitors and transfection of the si<jats:styled-content style="fixed-case">RNA</jats:styled-content>s targeting <jats:styled-content style="fixed-case">MSK</jats:styled-content>1 significantly blocked the <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> expression.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p><jats:styled-content style="fixed-case">IL</jats:styled-content>‐33 induces <jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> via <jats:styled-content style="fixed-case">ST</jats:styled-content>2‐<jats:styled-content style="fixed-case">ERK</jats:styled-content>1/2‐<jats:styled-content style="fixed-case">MSK</jats:styled-content>1 signaling pathway in bronchial epithelial cells. These data suggest that the <jats:styled-content style="fixed-case">IL</jats:styled-content>‐33/<jats:styled-content style="fixed-case">IL</jats:styled-content>‐17<jats:styled-content style="fixed-case">F</jats:styled-content> axis is involved in allergic airway inflammation and may be a novel therapeutic target.</jats:p></jats:sec>