ABSTRACT Introduction T helper 17 (Th17) cells have a significant effect in the pathogenesis of asthma, and signal transducer and activator of transcription 3 (STAT3) pathway activation is critical for Th17 cell differentiation. Timosaponin A-III (TA3) was reported to inhibit the STAT3 pathway. Here, we investigated whether TA3 improved asthma by inhibiting the STAT3 pathway. Methods Ovalbumin (OVA)-induced asthma murine models were developed, and TA3 (10 or 20 mg/kg) was gavage daily during OVA challenge. Murine naïve CD4+T cells were triggered for Th17 differentiation, and TA3 (5 or 10 μM) was used to treat cells during induction of Th17 differentiation. Results In vivo experiments showed that TA3 decreased airway inflammation, goblet cell and smooth muscle hyperplasia, α-smooth muscle actin and collagen deposition, Th17 differentiation, and STAT3/RORγt signaling activation in mice exposed to OVA. The inhibitory effect of TA3 on STAT3/RORγt signaling activation was also observed in in vitro experiments. Compared to positive control static (a specific inhibitor of STAT3), TA3 had a similar effect on Th17 differentiation. Discussion These findings indicate that TA3 may ameliorate Th17 cell differentiation by suppressing STAT3/RORγt signaling. Our data provide evidence of the potential benefits of TA3 for the treatment of asthma.
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