Objective: To observe the effect of Mongolia medicine Zhonglun'e Tang on the expressions of matrix metalloproteinase-3 (MMP-3) and MMP-9 in rats with collagen induced arthritis (CIA) and to study its treatment mechanism for rheumatoid arthritis (RA). Method: arthritis rat models were established by using type Ⅱ collagen. The rats were divided into normal group

model group

tripterygium wilfordii polycoride tablets group (9.45 mg · kg-1)

Mongolian medicine Zhonglun'e Tang high dose (5.4 g · kg-1)

medium dose (2.7 g · kg-1) and low dose (1.35 g · kg-1) groups. The drugs were given for 4 weeks

and then HE staining was used to observe the histopathologic morphology of synovial tissues. MMP-3 and MMP-9 levels in the serum of rats were measured by enzyme linked immunosorbent assay (ELISA). The expressions of MMP-3 and MMP-9 in the synovial tissues were detected by using immunohistochemistry and Western blot. Result: The levels of MMP-3 and MMP-9 in serum of model group were significantly higher than those in normal group (P<0.01);positive expressions of each drug group were lower than those in model group to varying degrees (P<0.01)

but there was no significant difference between Zhonglun'e Tang high dose group and tripterygium wilfordii polycoride tablets group. The results of immunohistochemistry method showed that

the expressions of MMP-3 and MMP-9 in mode group were significantly higher than those in normal group (P<0.01)

and there was statistically significant difference between Zhonglun'e Tang high dose group

tripterygium wilfordii polycoride tablets group were lower in protein expression of MMP-3 and MMP-9 than those in model group(P<0.05). The results of Western blot showed that the protein expressions of MMP-3 and MMP-9 in the treatment groups group were significantly lower than those in model group

with statistically significant difference (P<0.05). Conclusion: Zhonglun'e Tang could significantly decrease the MMP-3 and MMP-9 levels in serum of CIA rats

and reduce the positive expressions of synovial tissues. This may be the mechanism for treating RA.