Paeoniflorin attenuates allergic inflammation in asthmatic mice

Paeoniflorin (PF), one of the major active ingredients of Chinese peony, has demonstrated anti-inflammatory and immunoregulatory effects. However, it has remained unclear whether PF treatment can inhibit allergic inflammation in asthma. In this study, we evaluated the effects of PF on pulmonary function and airway inflammation in asthmatic mice. The allergic asthma models were established in BALB/c mice. The mice were sensitized and challenged with ovalbumin. Airway hyperresponsiveness was detected by direct airway resistance analysis. Lung tissues were examined for inflammatory cell infiltration. IL-5, IL-13, IL-17, and eotaxin in bronchoalveolar lavage fluid (BALF) and their mRNA expression in lung tissue were examined by ELISA and realtime PCR, respectively. The total IgE level in serum was measured by ELISA. The protein expression of p-ERK and p-JNK was detected by western blot. Our data showed that PF oral administration significantly reduced airway hyperresponsiveness to aerosolized methacholine and decreased IL-5, IL-13, IL-17 and eotaxin levels in the BALF, and decreased IgE level in the serum. Histological studies showed that PF administration markedly decreased inflammatory infiltration. Similarly, treatment with PF significantly inhibited IL-5, IL-13, IL-17 and eotaxin mRNA expression in lung tissues. The protein expression levels of p-ERK and p-JNK were substantially decreased after oral administration of PF. In summary, PF displayed anti-inflammatory effects in the OVA-induced asthmatic model by decreasing the expression of IL-5, IL-13, IL-17 and eotaxin. These effects were mediated at least partially by inhibiting the activation of MAPK pathway.