Electroacupuncture alleviates synovial inflammation in rheumatoid arthritis rats by suppressing caspase-1-mediated pyroptosis.

Rheumatoid arthritis (RA) causes inflammatory bone and cartilage damage. While electroacupuncture (EA) alleviates joint inflammation, its anti-inflammatory mechanisms remain unclear. Sprague-Dawley rats were randomly assigned to control, collagen-induced arthritis (CIA), EA (EA+CIA), and sham-EA (sham-EA+CIA) groups. Rats in the EA group received EA at unilateral ST36 (Zusanli) every other day from day 1. Paw swelling and paw withdrawal latency (PWL) were measured during the treatment. The levels of caspase-1, GSDMD, IL-1β, and IL-18 in the synovium were assessed after 28 days of EA treatment. Our findings demonstrated that inflammatory responses, such as the arthritis index, toe volume, PWL, and inflammatory cell infiltration, were significantly improved in the EA group compared with the CIA and sham-EA groups. Significant decreases in the levels of caspase-1, GSDMD, IL-1β, and IL-18 were observed in the synovium of RA rats that received EA. Furthermore, peripheral blood levels of the inflammatory cytokines IL-1β and IL-18 were significantly reduced in rats in the EA group. Electroacupuncture as implemented at ST36 was associated with reduced caspase-1-mediated pyroptosis-related markers in the joint synovium and decreased IL-1β and IL-18 levels in both synovium and serum in rats with CIA. Acupoint-specificity requires further validation using active-sham or componentresolved control designs.