Mice were exposed to OVA as previously described (25 ,26 (link)) to establish a model of acute asthma. When IL-27 was administered in a preventative manner to the mice in the OVA + IL-27 group (Fig. 1A), the mice received 50 µl PBS and 50 ng IL-27 intranasally twice a day from day-6 to day 7. However, the mice received 50 µl PBS alone on the same days when IL-27 was delivered in a therapeutic manner in the OVA and PBS groups (Fig. 1B). The mice were then sensitized with intraperitoneal (i.p.) injections of 100 µg OVA (Sigma-Aldrich; Merck KGaA), 2 mg alum (Thermo Fisher Scientific, Inc.) and 100 µl sterile endotoxin-free PBS (Invitrogen; Thermo Fisher Scientific, Inc.) on days 0 and 7 in the OVA and OVA + IL-27 groups. The mice received PBS instead of OVA on the same days in the PBS group. In the OVA group, the mice were challenged with 50 µl PBS and 100 µg OVA intranasally from days 14 to 18 under light isoflurane (3%) anesthesia (27 (link)). In the OVA + IL-27 group, the mice were treated intranasally with 50 µl PBS and 1 µg IL-27 1 h prior to OVA sensitization and subsequent challenge (50 µl PBS and 100 µg OVA) on days 0, 7 and 14-18. The mice received PBS alone on the same days in the PBS group. Each group included 8 mice.