Low-Frequency (1 Hz) Repetitive Trans-Spinal Magnetic Stimulation Attenuates NLRP3-Driven Neuroinflammation and Enhances Motor Recovery in Spinal Cord-Injured Mice.

PURPOSE

Investigate the effects of repetitive Trans-Spinal Magnetic Stimulation (rTSMS) on motor function recovery and the underlying mechanisms in mice after spinal cord injury.

METHODS

rTSMS was applied both in vivo and in vitro, Motor function was evaluated by the Basso Mouse Scale (BMS), grid walking errors, and Motor Evoked Potentials (MEPs). Cell viability, oxidative stress markers, and key proteins including AQP4, Bax, Bcl-2, cleaved caspase-3, inflammatory cytokines, and NLRP3 inflammasome components were analyzed. Retrograde tracing using rAAV/Retro and neuronal markers (NeuN, MAP2, β-III-tubulin) were analyzed by the Microplate Reader, Western Blot, ELISA, and Immunofluorescence (IF).

RESULTS

1 Hz rTSMS improved motor recovery, reduced lesion size, and enhanced MEPs compared to 20 Hz. It decreased spinal edema and oxidative stress, suppressed apoptosis, and inhibited NLRP3 inflammasome activation in microglia. GFAP was downregulated, while BDNF and anti-inflammatory cytokines (IL-4, IL-10) increased. Retrograde tracing showed enhanced survival of cortical motor neurons after 1 Hz rTSMS. In vitro, BV2 supernatants after MS reduced pro-inflammatory cytokines and promoted PC12 neuronal survival and maturation.

CONCLUSION

Specific frequency rTSMS at 1 Hz can inhibit NLRP3 inflammasome expression, reducing inflammation, promoting neuroprotection, and aiding hindlimb recovery after spinal cord injury in mice.