Abstract: The toll-like receptors (TLRs) member, TLR4, can recognize a various of lipopolysaccharide (LPS) of gram-negative bacteria to involve host immune and inflammation response. This study was aimed to explore the effects ofTLR4on the expression of inflammatory cytokine genes and chicken macrophage HD11 apoptosis, through interfering the expression ofTLR4, so as to provide some useful information in molecular regulation mechanism ofTLR4on chicken immune response. Different doses of LPS were used to infect chicken HD11 cells, and the expression levels ofTLR4and inflammatory related genes were identified at different time points after infection. TLR4-siRNA were designed and transfected to chicken HD11 cells in vitro, and then quantitative real time PCR (qRT-PCR) and flow cytometry were, respectively, applied to detect the expression of TLR4 and inflammatory related genes, as well as cell apoptosis. The results showed that the optimum condition of LPS was 1 μg/mL infection 8 h to induce the expression of geneTLR4,IL-1β,IL-8andIL-6. In chicken HD11 cells, interferingTLR4gene could significantly decrease the expression of pro-inflammatory genesIL-1β,IL-6,IL-8and TNF-α (P<0.05), and inhibit cell apoptosis under LPS infection, while the expression levels of anti-inflammatory genes TGF-β and IFN-α was decreased with no significant difference (P>0.05). This study confirmed that regulating the expression ofTLR4gene can directly affect the inflammatory response of chicken HD11 cells to LPS, which provide new ideas and intervention targets for controlling excessive inflammatory response, as well as, have practical significance for alleviating stress-induced pathological damage and improving poultry health.

Key words: TLR4, LPS, chicken HD11 macrophages, immune and inflammation, knockdown vector