Background
Pulmonary infections resulting from respiratory syncytial virus (RSV) continue to pose a significant threat to the well-being of infants and the elderly, but there is no safe, effective and specific treatment except symptomatic treatment. Forsythia Suspensa Leaf (FSL) is cold in nature and bitter in taste, and has the efficacy of clearing away heat and toxic materials. Previous research by our research group showed that the active components in FSL have the pharmacological effect of anti-RSV. Based on that, this study aims further to clarify the anti-RSV active components and mechanism of FSL.
Conclusion
Phillyrin, the active component in FSL, can not only directly inhibit the replication of RSV, but also effectively control the inflammatory reaction caused by RSV infection and improve lung injury, which is expected to become a potential drug against RSV pneumonia.
Methods
Firstly, we established the BALB/c mouse model of RSV infection, assessed the in vivo anti-RSV efficacy, and determined the optimal dosage of FSL and its active components. Evaluation parameters included body weight changes, organ indices, lung tissue pathological sections, lung tissue viral load, and inflammatory factors. Additionally, we used RT-PCR, Western Blot and other molecular biology techniques to determine the expression changes of key factors such as Nrf2 and NLRP3 in PI3K/Akt-NLRP3 pathway, and revealed the anti-RSV mechanism of FSL and its active components.
Results
Pharmacodynamic experiments in animals showed that the FSL Low (0.4 g/kg·d), RosA Low (100 mg/kg·d) and Phillyrin Medium (100 mg/kg·d) groups could effectively improve the pathological conditions of mice with RSV pneumonia, such as weight loss, the level of pulmonary inflammatory factors and the increase of viral load. In addition, oral administration of Phillyrin at a dose of 100 mg/kg d to RSV-infected mice can effectively control the trend that the expression of Nrf2 protein decreases and the expression of NLRP3 protein increases in RSV pneumonia mice.