[The expression and significance of TLR4, MyD88 and NF-κB mRNA in mouse lymph node of experimental autoimmune myositis].

Aim: To investigate TLR4, MyD88 and NF-κB mRNA levels in mouse lymph node with experimental autoimmune myositis(EAM)and determine the role of TLR4 in autoimmune myositis.

Methods: Thirty femal BALB/c mice were randomly divided into five groups (n=6 animals per group): group 1 was the control, while animals in other four groups were killed at different time point: group 2 in the first week, group 3 in the second week, group 4 in the third week and group 5 in the fourth week since they had been given myosin for preparing EAM. The expressions of TLR4, MyD88 and NF-κB mRNA were measured with real-time fluorescent quantitative polymerase chain reaction.

Results: (1)The expressions of TLR4, MyD88 and NF-κB mRNA in each EAM group were significantly high compared with those in the normal control group, which was significantly highest in group 3 of all(P<0.01) and significantly higher in group 4 than in group 5(P<0.01).(2)The expression level of TLR4 mRNA had significant positive correlations with the expressions of MyD88 mRNA and NF-κB mRNA(r=0.906, r=0.967, P<0.01), and the latter two also had significant positive correlations(r=0.919, P<0.01).

Conclusion: TLR4 played an important role in the development of autoimmune myositis and run its function mainly by MyD88-dependent pathway that could activate NF-κB for promoting the release of inflammatory factors.