To explore the mechanism of moxibustion on the treatment of rheumatoid arthritis (RA) in the perspective of programmed cell death-1 and its ligand 1 (PD-1/PD-L1).
A total of 30 Japanese big ear white rabbits were randomly divided into a control group, a model group and a moxibustion group, 10 rabbits in each one. In the model group and the moxibustion group, RA model was prepared by the injection of Freund's complete adjuvant (FCA) into the hind knee joint cavities of each rabbit. In the control group, 0.9% sodium chloride solution of the same dose was injected. On the 8th day of experiment, in the moxibustion group, moxibustion was applied to "Shenshu" (BL 23) and "Zusanli" (ST 36), 5 cones at each acupoint, on the bilateral sides alternatively, once a day, 6 treatments as one course, with an interval of 1 days between the treatment courses. Totally, 3 courses of treatment were required. On the 1st, 7th, 14th, 21st and 28th days of experiment, successively, the circumference of the bilateral knee joints was measured with the tape. On the 28th day of experiment, H.E. staining was adopted to observe the histopathological morphology and to evaluate the score of knee synovial tissue. ELISA was used to determined the concentrations of soluble PD-1 (sPD-1) and its ligand 1 (sPD-L1), the interleukin 2 (IL-2) and IL-17 in knee synovial fluid and the concentrations of sPD-1 and sPD-L1 in serum. The histochemistry method was used to determine the expressions of membrane PD-1 (mPD-1) and its ligand 1 (mPD-L1) in spleen tissue.
On the 14th, 21st and 28th days of experiment, the circumference of both knee joints was increased in each of the rabbits in the model group as compared with the control group (
Moxibustion could inhibit the over-activation of T cells by enhancing the negative regulation of PD-1/PD-L1 signaling pathway so as to play its effect in treatment of RA.