Protective effects of astragaloside IV on IL‑8‑treated diaphragmatic muscle cells

The diaphragmatic fatigue that results from airflow obstruction is associated with the severe morbidity of patients with chronic obstructive pulmonary disease. Astragaloside IV (AS-IV) has antioxidant, anti-apoptotic and anti-inflammatory activities in various cell types. The present study aimed to evaluate the protective effects of AS-IV in diaphragmatic muscle cells. Diaphragmatic muscle cells extracted from neonatal rats were treated with a series of AS-IV concentrations (5, 10 or 20 mg/l) and the AKT inhibitor GSK690693 in the presence of interleukin-8 (IL-8). Cell proliferation and AKT phosphorylation were measured using Cell Counting Kit-8 and western blot assays, respectively. Cell apoptosis and reactive oxygen species (ROS) production were evaluated using flow cytometric analysis. Caspase activity and concentrations of proinflammatory factors (tumor necrosis factor-α, IL-6 and IL-8) were assessed using a caspase colorimetric assay and ELISA, respectively. IL-8 treatment resulted in decreased rates of cell proliferation and increased rates of AKT phosphorylation, cell apoptosis, caspase 3/9 activity, ROS production and proinflammatory factor production. AS-IV and GSK690693 treatment reversed the effects of IL-8. The effects of AS-IV were dose-dependent. The present results suggested that AS-IV is a candidate for the treatment of diaphragmatic fatigue due to its antioxidant, anti-apoptotic and anti-inflammatory activity.