Therapeutic effects of forsythiin on mice infected with respiratory syncytial virus
Objective To explore the effect of forsythin on the Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)signaling pathway in mice infected with respiratory syncytial virus(RSV).Methods A respiratory infection model was established by intranasal inoculation of RSV.Mice infected with RSV were randomly divided into model group,experimental group,and positive control group,while control group received an equal volume of DMEM medium by nasal drops.The experimental group was administered forsythin(200 mg·kg-1·d-1)by gavage,the positive control group received ribavirin(27.6 mg·kg-1·d-1)by gavage,and both the control and model groups were given an equal volume of 0.9%NaCl,with continuous intervention for 14 days.Interleukin-4(IL-4),IL-13,and interferon-gamma(INF-γ)levels in bronchoalveolar lavage fluid(BALF)were detected by enzyme-linked immunosorbent assay;transcription levels of TLR4 and MyD88 mRNA in lung tissue were detected by real-time fluorescent quantitative polymerase chain reaction;and the positive expression of TLR4 and MyD88 proteins in lung tissue were detected by immunohistochemistry.Results The levels of IL-4 in BALF of the control group,model group,experimental group,and positive control group were(490.63±27.45),(1 382.37±41.28),(970.32±36.01),(738.41±30.27)pg·mL-1,respectively;IL-13 levels were(4.02±2.63),(18.33±5.62),(12.97±3.73),and(7.51±2.74)pg·mL-1,respectively;INF-γ levels were(54.42±2.68),(30.26±4.68),(42.80±3.36),and(45.01±3.82)pg·mL-1,respectively;the expression of TLR4 mRNA in lung tissue were 0.43±0.06,1.63±0.12,0.98±0.10,and 0.86±0.06,respectively;the expression of MyD88 mRNA in lung tissue were 0.56±0.09,1.78±0.15,1.02±0.07,and 0.75±0.06,respectively;the average optical density of TLR4 protein in lung tissue were 0.02±0.00,0.11±0.02,0.06±0.01,and 0.03±0.00,respectively;the average optical density of MyD88 protein were respectively 0.01±0.00,0.09±0.02,0.05±0.01,and 0.03±0.01,respectively.Compared the model group with the control group,and compared the experimental and positive control groups with the model group,above indicators showed statistically significant differences(all P<0.05).Conclusion Forsythin can alleviate lung damage in mice infected with RSV,possibly by regulating the balance of immune cells and inhibiting the TLR4/MyD88 signaling pathway.
forsythinrespiratory syncytial virusToll like receptor 4myeloid differentiation factor 88inflammatory response