The antiviral mechanism of the crude extract from the flowers of Trollius chinensis based on TLR 3 signaling pathway

The effects of crude extract from the flowers of Trollius chinensis on expressions of mRNA and proteins related to vital genes (TLR 3, TBK 1, IRF 3 and IFN beta) in TLR 3 signaling pathway were investigated in the presence/absence of Polyinosinic acid-polycytidylic acid (PolyI: C) to ascertain the antiviral mechanism of these flowers. Real-time PCR and western blot were applied to determine the expressions of mRNA and proteins, respectively, and immunofluorescence assay was employed to study the effect on IRF 3 distribution between nuclei and cytoplasma. In the absence of PolyI:C, the crude extract reduced the mRNA expression of TLR 3, IRF 3 and IFN beta and the protein expression of TLR 3, and increased the protein expression of IRF 3 and the distribution of IRF 3 in nuclei. In the presence of PolyI:C, the extract reduced the mRNA and protein expressions of TLR 3 and the mRNA expression of IFN beta, meanwhile inhibited the translocation of IRF 3 into nuclei. The antiviral mechanism of the crude extract from the flowers of T. chinensis is to protect the host from inflammatory damage through intervening the TLR 3 signaling pathway and reducing the secretion of inflammatory factors.