[Effect of electroacupuncture on articular morphological changes and serum inflammatory factors and synovial MMPs in collagen-induced arthritis rats].

Objective: To observe the effect of electroacupuncture (EA) of "Zusanli"(ST36) and "Sanyinjiao"(SP6) on serum TNF-α, IL-1β, and IL-6 and expression of synovial matrimetalloproteinases (MMPs) and articular morphology in collagen-induced arthritis (CIA) rats, so as to explore its mechanisms underlying relief of arthritis.

Methods: Thirty male SD rats were randomly divided into normal control, CIA model and EA groups (n=10 rats per group). The arthritis model was induced by multi-point intradermal injection of bovine type Ⅱ collagen emulsion. EA (2 Hz/100 Hz, 1 mA) was applied to bilateral ST36 and SP6 for 30 min, once a day for 28 days. The hind-limb paw volume was measured and the arthritis index (AI) score given according to the swelling degree, rigidity and deformity of the ankle joint (0-4 points). After EA intervention, the morphological damage of the affected ankle joints was revealed by H.E. staining, safranin O-fast green staining, and tartrate-resistant acid phosphatase (TRAP) staining, separately. The levels of serum TNF-α, IL-1β, and IL-6 were measured by ELISA, and the expression levels of MMP-1, MMP-3, MMP-13, and receptor activator of nuclear factor Kappa B ligand (RANKL) in the synovial tissue were detected by Western blot.

Results: Compared with the normal control group, the paw volume, AI score, TRAP-revealed number of osteoclasts, contents of serum TNF-α, IL-1β and IL-6, and expression levels of MMP-1, MMP-3, MMP-13 and RANKL proteins were significantly increased in the model group (<0.01, <0.05). Following the intervention, the paw volume, AI score, number of osteoclasts, contents of serum TNF- α, IL-1β and IL-6, and expression levels of MMP-1, MMP-3, MMP-13 and RANKL proteins were significantly decreased in the EA group (<0.05, <0.01) in contrast to the model group. H.E. and safranin O-fast green staining showed rough articular cartilage surface with thinned cartilage layer, obvious hyperplasia of the synovial tissue with many inflammatory cells, and serious damage and degradation of the cartilage matrix in the model group, these situations were relatively milder in the EA group.

Conclusion: EA of ST36 and SP6 can reduce the articular damage in collagen-induced arthritis rats, which is associated with its function in reducing inflammatory response and down-regulating the expression of synovial MMP-1, MMP-3, MMP-13 and RANKL proteins.