Pterostilbene suppresses oxidative stress and allergic airway inflammation through AMPK/Sirt1 and Nrf2/HO-1 pathways

Introduction: Pterostilbene (Pts) may be used for allergic asthma treatment. The AMPK/SIRT1 and Nrf2/HO-1 pathways are potential targets for asthma treatement. However, the relationship between Pts and AMPK/SIRT1 and Nrf2/HO-1 pathways in asthma is unclear. Herein, we aim to explore the pharmacological effects of Pts on oxidative stress and allergic inflammatory response as well as the mechanism involving AMPK/SIRT1 and Nrf2/HO-1 pathways.

Methods: Asthma model was established in mice with ovalbumin (OVA). The model mice were treated by different concentrations of Pts. Lung pathological changes were observed through histological staining. In vitro, lipopolysaccharide (LPS)-stimulated 16HBE cells were treated with Pts. The siAMPKα2, siSirt1 and siNrf2 knockdown, and treatment with compound C, EX-527 or ML385 were also performed in 16HBE cells. Enzyme-linked immunosorbent assay was used to detect interleukin-4 (IL-4), IL-13, IL-5, total and OVA specific immunoglobulin E (IgE), and interferon γ (IFN-γ). Pneumonography was used to measure the airway hyperreactivity (AHR). Superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels were also detected. Immunohistochemistry, Western blot and immunofluorescence were used to measure protein levels.

Results: Pts significantly attenuated lung inflammatory cell infiltration and goblet cell proliferation. Meanwhile, Pts treatment could reduce IL-4, IL-13, IL-5, and IgE (total and OVA specific) levels in the asthma model mice. However, IFN-γ in bronchoalveolar lavage fluid was elevated. In addition, Pts reduced AHR. We also found that Pts treatment promoted serum SOD and CAT, and reduced MDA. In vitro results showed that Pts treatment promoted iNOS, TNF-α, COX-2, IL-1β, and IL-6 expressions in 16HBE cells, prolonged G0/G1 phase of the cell cycle, and resulted in a shortened G2M phase. Moreover, we found that Pts promoted the phosphorylation of AMPK in 16HBE, and meanwhile inhibited the increase of ROS induced by LPS. Additionally, Pts treatment inhibited p-AMPK, SIRT1, Nrf2 and HO-1, which in turn leads to the alleviation of AMPK/SIRT1 and Nrf2/HO-1 pathways.

Conclusion: Pts alleviated oxidative stress and allergic airway inflammation via regulation of AMPK/Sirt1and Nrf2/HO-1 signaling pathways.