ObjectiveTo observe whether interleukin-27 (IL-27) intervention could diminish allergic airway inflammation of mouse asthma induced by ovalbumin (OVA) and to investigate the related molecular mechanisms. MethodsSixty female C57/6J mice were randomly divided into six groups, a control group, an asthma group, two IL-27 prevention groups and two IL-27 treatment groups. Based on being sensitized and challenged with OVA in the asthma model, two kinds of IL-27 intervention asthma models were set up, one of which was low-dose multiple prevention model, the other was high-dose few times treatment model. HE stain and inflammation score were done for the lungs. CD4+ T cells were purified from mice spleen and cultured under Th2 medium with/without IL-27. Interleukin-4 (IL-4) was measured by ELISA. CD4+ T cells were cultured under different stringent Th2 medium and stimulated by IL-27. The level of total signal transducer and activator of transcription-1 (STAT1) protein and phos-STAT1 were tested by Western blot. ResultsIn low-dose multiple prevention group, IL-27 inhibited inflammation around bronchial and vascular obviously, the inflammation score was lower than the asthma group (P < 0.05), while the treatment group had no obvious statistical significance (P > 0.05). IL-27 repressed Th2 differentiation of naïve CD4+ T cells which was independent of interferon-γand IL-10. This effect was via STAT1 signaling pathway. CD4+ T cells from asthma mice or cultured under high-IL-4 inducing medium were found impairment of STAT1 phosphorylation. ConclusionsIL-27 could inhibit Th2 differentiation of naïve CD4+ T cells, but not in already committed Th2-CD4+ T cells. The inhibition effect of IL-27 for airway inflammation is obvious in prevention group, while the treatment group shows obviously resistance to inhibitory effect of IL-27. Already committed Th2-CD4+ T cells existed in asthma airway might be the reason for IL-27 resistance.