Liu Zhenyi, Guo Haotong, Zhi Yan, Jiang Xiaorui, Zhang Qian
College of Animal Science and Technology, Beijing University of Agriculture, Beijing, China.
YanTai Yuhuangding Hospital Affiliated to Qingdao University, Yantai, China.
Front Immunol. 2025 May 8;16:1593691. doi: 10.3389/fimmu.2025.1593691. eCollection 2025.
The H9N2 avian influenza virus, although not highly pathogenic, still poses ongoing risks to poultry health and food security due to its ability to resist vaccines and its potential to spread to humans.
This study investigated the effects of baicalin, a flavonoid derived from , on respiratory mucosal immunity during H9N2 infection. In vitro experiments were conducted using MLE-12 alveolar epithelial cells, and in vivo evaluations were performed in a mouse model of H9N2 infection.
Baicalin treatment enhanced the expression of antiviral proteins Mx1 and PKR in a dose- and time-dependent manner, helping to counteract the virus's suppression of these defense proteins. In addition to strengthening this epithelial barrier, baicalin has both antiviral and immune-regulating effects: it directly blocks viral replication and helps restore the CD4+/CD8+ T cell ratio in H9N2-infected mice. Most importantly, baicalin reduces lung damage and spleen shrinkage while keeping the immune system balanced. These results show that baicalin enhances mucosal antiviral defenses by simultaneously regulating innate antiviral pathways (Mx1 and PKR) and restoring adaptive immune balance (CD4+/CD8+ T-cell ratio).
These dual protective effects highlight baicalin's potential as a natural therapeutic strategy for improving mucosal immunity against vaccine-resistant influenza viruses such as H9N2, contributing valuable insights into plant-derived immunomodulatory approaches against emerging zoonotic viral threats.
H9N2禽流感病毒虽然致病性不强，但由于其具有疫苗抗性以及可能传播给人类，仍然对家禽健康和食品安全构成持续风险。
本研究调查了从黄芩中提取的黄酮类化合物黄芩苷对H9N2感染期间呼吸道黏膜免疫的影响。使用MLE-12肺泡上皮细胞进行体外实验，并在H9N2感染的小鼠模型中进行体内评估。
黄芩苷处理以剂量和时间依赖性方式增强了抗病毒蛋白Mx1和PKR的表达，有助于对抗病毒对这些防御蛋白的抑制。除了加强这种上皮屏障外，黄芩苷还具有抗病毒和免疫调节作用：它直接阻断病毒复制，并有助于恢复H9N2感染小鼠的CD4+/CD8+T细胞比例。最重要的是，黄芩苷减少了肺损伤和脾脏萎缩，同时保持免疫系统平衡。这些结果表明，黄芩苷通过同时调节先天性抗病毒途径（Mx1和PKR）和恢复适应性免疫平衡（CD4+/CD8+T细胞比例）来增强黏膜抗病毒防御。
这些双重保护作用凸显了黄芩苷作为一种天然治疗策略的潜力，可用于改善针对H9N2等疫苗抗性流感病毒的黏膜免疫，为针对新出现的人畜共患病毒威胁的植物源免疫调节方法提供了有价值的见解。
