Objective   To study the inhibitory effect of chloroquine on TLR4-MyD88-independent signaling pathway lipopolysaccharide/endotoxin (LPS)-induced RAW264.7 cells.    Methods   Effect of various chloroquine (5、10、20、40、60 μg/ml) concentrations on viability of RAW264.7 cells was detected by MTT test. TNF-α and IL-6  levels in culture supernatant were measured at 2

6

12

18

24 h by ELISA

and RT-PCR for the detection of expressions of TNF-α

IL-6，TLR4 mRNA and TRAM mRNA. EMSA was used to detect NF-κB activity. IκBα phosphorylation and IRF3 degradation were assayed by Western blotting.    Results   Chloroquine had no effect on the viability of RAW264.7 cells at a concentration of less than 40 μg/ml （P0.05）. The expression of TNF-α

IL-6

TLR4 and TRAM in LES-induced RAW264.7 cells at protein and mRNA level was significantly inhibited (P0.05

P0.01). EMSA showed that LPS inhibited the activity of NF-κB and Western blotting showed that LPS could suppress the phosporylation of IκBα and the degradation of IRF3.    Conclusion   Chloroquine inhibits TLR4-MyD88-independent signaling pathway in LPS-induced RAW264.7 cells.