Abstract: BACKGROUND: Acupotomy, as one of the representative therapies of minimally invasive interventional therapy, has been applied to the clinical treatment of lumbar disc herniation, which can antagonize nerve root inflammatory response in lumbar disc herniation with precise curative effects, but its potential mechanism of action remains to be explored.
OBJECTIVE: To investigate how acupotomy intervention affects the mitochondrial-mitochondria-associated endoplasmic reticulum membranes-endoplasmic reticulum interaction stress-mediated NLRP3 inflammasome activation in the microenvironment of nerve roots in the model rabbits of lumbar disc herniation.
METHODS: Forty healthy adult New Zealand white rabbits were randomly divided into a blank control group (10 rabbits) and a model group (30 rabbits). Animal models were established in the model group through a standard autologous nucleus pulposus transplantation method. Once the model was successfully created, the model group was randomly subdivided into a model control group (10 rabbits), an electroacupuncture intervention group (positive control group) (10 rabbits), and an acupotomy intervention group (10 rabbits). Acupotomy and electroacupuncture interventions were performed 1 week after modeling. Rabbit dorsal root ganglion neurons were isolated and cultured at 3 weeks after intervention. TUNEL staining was used to detect cell apoptosis. Western blot assay was used to measure the expression levels of NLRP3, MAMs-related proteins, endoplasmic reticulum stress marker protein GRP78, specific marker protein CHOP, and the key pathway PERK axis TXNIP protein. Fluorescent probe staining (Mito Tracker and ER Tracker) and transmission electron microscopy were used to observe mitochondrial-endoplasmic reticulum structural coupling. Flow cytometry was used to detect Ca2+ levels, and reactive oxygen species content was measured using reactive oxygen probes.
RESULTS AND CONCLUSION: (1) Compared with the model control group, the acupotomy group had a significant reduction in apoptosis rate (P=0.000 2), the protein expressions of NLRP3 (P=0.014 4), IP3R (P=0.013 2), GRP75 (P=0.009 9), VDAC1 (P=0.000 3), GRP78 (P=0.006 5), CHOP (P=0.008 5), and TXNIP (P=0.001 5) and the levels of Ca2+ (P < 0.000 1) and reactive oxygen species (P=0.039 2) as well as a significant increase in the protein expression of MFN2 (P=0.010 8). (2) Fluorescent probe staining results showed that the co-localization level of mitochondria and endoplasmic reticulum was highest in the model control group and lowest in the blank control group; the co-localization level of mitochondria and endoplasmic reticulum in the acupotomy group was higher than that in the blank control group but lower than the model control group. (3) Transmission electron microscopy observations revealed enhanced contact between mitochondria and endoplasmic reticulum in the model control group and less contact in the blank control group, and there was increased contact in the acupotomy intervention group compared with the blank control group, but lower than in the model control group. To conclude, acupotomy intervention can help manage the stress between mitochondria and the endoplasmic reticulum, modulate mitochondria-endoplasmic reticulum contact sites, reduce Ca²⁺ influx, reactive oxygen species generation, and mitochondrial dysfunction, thereby inhibiting the formation of the NLRP3 inflammasome. This explains the upstream mechanism by which acupotomy inhibits NLRP3 inflammatory vesicle assembly by modulating mitochondria-endoplasmic reticulum interaction stress, revealing the deep action targets of acupotomy in treating lumbar intervertebral disc herniation, and providing a certain theoretical basis for the treatment of lumbar intervertebral disc herniation by acupotomy.

Key words: acupotomy, lumbar disc herniation, nerve root inflammatory response, inflammasome, regulatory mechanism, cellular pyroptosis