Electroacupuncture improves gout arthritis pain via attenuating ROS-mediated NLRP3 inflammasome overactivation

Gout is a painful inflammatory condition caused by the deposition of uric acid crystals in the joints, affecting millions of people worldwide. Pain management traditionally relies on anti-inflammatory drugs and colchicine, medications that can cause significant adverse effects when used continuously. This study investigated how electroacupuncture (EA) may offer a safe and effective therapeutic alternative for relief of gouty pain. The researchers established a gouty arthritis model in mice through injection of monosodium urate crystals into the ankle joint, reproducing the main features of human gout: intense pain, inflammation, and limitation of movement.

The experimental protocol included four groups: control (PBS), gout model, gout treated with electroacupuncture, and gout treated with sham acupuncture. Electroacupuncture was applied at the ST-36 (Zusanli) and BL-60 (Kunlun) points bilaterally, using alternating frequency of 2/100 Hz for 30 minutes, in two sessions. The results demonstrated that electroacupuncture significantly reduced mechanical allodynia and thermal hyperalgesia in animals with gout, in addition to substantially improving locomotion parameters that were compromised by pain. Gait analysis revealed that animals treated with EA recovered movement patterns closer to normal, while the sham acupuncture group showed no improvements.

From a molecular standpoint, the study revealed that EA acts through modulation of the NLRP3 inflammasome, a protein complex crucial in the inflammatory response of gout. EA significantly reduced the expression of inflammasome components (NLRP3, Caspase-1, ASC) and pro-inflammatory cytokines (IL-1β, IL-18) in joint tissues. Pharmacological experiments confirmed this pathway: specific blockade of NLRP3 mimicked the analgesic effects of EA, while its activation reversed the benefits of treatment. An important finding was that EA exerts potent antioxidant effects, reducing reactive oxygen species (ROS) and lipid peroxidation products in inflamed tissues.

Oxidative stress is an upstream trigger for NLRP3 inflammasome activation, and the ability of EA to modulate this process represents a fundamental therapeutic mechanism. The research also demonstrated that EA decreases neutrophil infiltration in the articular synovium, cells that significantly contribute to excessive ROS production during gouty inflammation. In addition to peripheral anti-inflammatory effects, the study investigated changes in sensory neurons. Gout induced overexpression of the TRPV1 channel, an important pain receptor, in dorsal root ganglion neurons.

EA reduced both the expression and functional activity of these channels, as confirmed by calcium imaging experiments in living cells. This effect was mediated by reduction of NLRP3 inflammasome activation, establishing a clear connection between peripheral anti-inflammatory effects and modulation of central nociceptive sensitization. The clinical implications are substantial. While current pharmacological treatments for gout focus mainly on symptomatic suppression of inflammation, electroacupuncture demonstrates the ability to address multiple aspects of disease pathophysiology simultaneously: reduction of local inflammation, protection against oxidative damage, and modulation of neural sensitization.

This multitarget approach may explain the observed clinical efficacy of acupuncture in the management of gouty pain. The study has some important limitations. It was conducted exclusively in an animal model, requiring validation in human clinical studies. The follow-up duration was limited to 24 hours, not allowing assessment of long-term effects.

In addition, although the study elucidated important mechanisms, other molecular targets may be involved in the therapeutic effects of electroacupuncture.