Traditional Chinese medicine andrographolide sulfonate alleviates airway inflammation by supressing TRL3-TRIF in mice post respiratory syncytial virus infection

Abstract Background Andrographolide sulfonate is a proprietary Traditional Chinese Medicine used for the treatment of childhood respiratory tract infections. However, its effective role in respiratory syncytial virus (RSV) infection remain unclear. Methods BALB/c mice were infected with RSV and inoculated intraperitoneally or intranasally with andrographolide sulfonate daily for 5 days. Lung damage was measured using hematoxylin and eosin staining. Bronchoalveolar lavage fluid (BALF) was used for total cell counts and interferon-γ (IFN-γ) detection based on enzyme-linked immunosorbent assay (ELISA). The expression levels of the RSV N gene and Toll-like receptor (TLR) mRNA were detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the expression levels of the N protein, TLR2/3, and TRIF were detected by western blot analysis. Results Intraperitoneal injection of andrographolide sulfonate did not suppress RSV-induced inflammation, whereas intranasal administration reduced the total number of inflammatory cells in the BALF and pathological damage in the lungs. Furthermore, IFN-γ production was significantly decreased in the BALF, as were the N gene and protein expression levels. The RSV N gene was positively correlated with lung inflammation. After intranasal treatment with andrographolide sulfonate, lung TLR3 and TRIF expression were also reduced compared to the the RSV group. Conclusions Intranasal administration of andrographolide sulfonate reduces RSV replication and RSV infection-induced substance inflammation via TLR3-TRIF. Andrographolide sulfonate aerosol inhalation may be a better treatment for viral respiratory diseases.