Objective      To observe  the efficacy of Qianghuo Erhuang Decoction (QED

a set prescription of traditional Chinese herbs) in the treatment of adjuvant-induced arthritis in rats and explore the mechanism by its effect on Treg/Th17 cells.       Methods      Male SD rats were induced to adjuvant arthritis (AA) model. There were 6 groups of ra

ts in this study

including normal control group (oral taking of normal saline)

AA group (normal saline)

AA+methotrexate group (MTX

0.4 mg/kg per week)

AA+high-

moderate- and low-dose QED groups (daily dose: 4.5

9 and 18 g/kg

respectively). From the first day of joints swelling

the rats were given with corresponding agents through oral taking or intragastric injection. The changes of arthritis index score were observed during the following 4 consecutive weeks. Hematoxylin-eosin (HE) staining was used to evaluate joint histological changes. The proliferation of splenic lymphocytes was detected ex vivo by CCK-8 assay

and the percentages of T helper 17 (Th17) and T regulatory (Treg) cells in the spleen were measured by flow cytometry.       Results      The arthritis index score was significantly decreased in the MTX group (24 d: 1.33±1.56

28 d: 0.17±0.28

P0.01) and high-dose QED group (24 d: 3.00±1.33

28 d: 0.67±0.67

P0.01) than the AA group

and significant inhibited proliferation of splenic lymphocytes (the MTX group 24 h: 0.25±0.03

48 h: 0.25±0.03; 72 h: 0.27±0.01

P0.01; the high-dose QED group 24 h: 0.26±0.03

48 h: 0.25±0.03

72 h: 0.27±0.01

P0.01) and amelioration of synovial tissue inflammation were observed in the 2 groups. Compared with the normal control

the percentage of Treg cells [(5.75±0.46)%

P0.01

]

was decreased

while that of Th17 cells [(1.84±0.45)%

P0.01

]

was increased

and their ratio was in an imbalanced state. High-dose QED resulted in an increase of percentage of Treg cells [(11.19±2.01)%

P0.01

]

and an decrease of percentage of Th17 cells [(0.98±0.35)%

P0.05

]

. The moderate- and low-dose QED had no therapeutic effect when compared with the AA group (P0.05).       Conclusion      High dose of QED (18 g/kg) exerts certain therapeutic effect for AA

which might be due to its correcting the imbalance of CD4

+

T lymphocytes subsets

Treg/Th17.