Objective To observe the effects of moxibustion on the ultrastructure of synovial cells of knee joint and serum cytokines in adjuvant arthritis（AA） rats

and to explore the potential mechanism of moxibustion in treatment of rheumatoid arthritis. Methods Forty-five Wistar male rats were randomly divided into a normal group

a model group and a moxibustion group

with 15 rats in each group. In the model group and the moxibustion group

the AA model was replicated under wind

cold and humid environment and by injection with complete freund’s adjuvant. In the moxibustion group

moxibustion at "Zusanli"（ST 36） and "Shenshu"（BL 23） was used

20 min each time

once daily

for consecutive 21 days. In the normal group and the model group

no intervention was processed. The scores of the knee joint swelling degree（JSD） and arthritis index（AI） were compared among groups. The ultrastructure of synovial cells of knee joint were observed under transmission electron microscope（TEM）. The levels of serum cytokines such as tumor necrosis factor-α（TNF-α）

interieukin（IL）-1β

IL-6 and IL-10 were detected using ELISA method. Results Compared with the normal group

JSD and AI scores

the levels of TNF-α

IL-1β and IL-6 were increased（P<0.01）

while IL-10 was reduced（P<0.01） in the model group after intervention. JSD and AI scores

and the levels of TNF-α

IL-1β and IL-6 were lower（P<0.05

P<0.01）

while the level of IL-10 was higher（P<0.01） in the moxibustion group compared with the model group. Compared with the normal group

the ultrastructure of synovial cell was obviously damaged in the model group

and the damage was attenuated in the moxibustion group compared with the model group. Conclusion Moxibustion can reduce the symptoms of arthritis in AA rats

which may be related to the improvement of the ultrastructure of synovial cells and the regulation of cytokines.