Porcine CD14 gene silencing partially inhibited the bacterial immune response mediated by TLR4 signaling pathway

Cluster of differentiation antigen 14 (CD14) is the membrane receptor protein in Toll-like Receptor 4 (TLR4) signaling pathway, which plays an important regulation role in not only innate immune response but also adaptive immune response. In this study, the pig kidney epithelial cell (PK15) line with CD14 gene silencing mediated by lentivirus was established and cells of CD14-RNAi and NC group were exposed to three kinds of Escherichia coli (E. coli F18ab, E. coli F18ac and E. coli K88ac) and LPS. Then qPCR and western blot were used to detect expression levels of TLR4 signaling pathway-related genes. Finally, ELISA was used to detect the level of proinflammatory cytokines in the cell culture supernatant. The results showed that the expression level of TLR4 signaling pathway-related genes in the entire signal pathway had obvious increases when cells were exposed to the stimulation induced by E. coli and LPS. In addition, the expression levels of CD14-RNAi group were overall significantly lower than NC group (P < 0.05 or P < 0.01), which was the same with the release levels of proinflammatory cytokines. This study revealed that pig CD14 gene silencing partially inhibited immune response to E. coli F18 invasion mediated by TLR4 signaling pathway.