Ccn1 Mediates Pyroptosis and Purine Metabolism Pattern Shifts in a High-Uric Acid Microenvironment After Spinal Cord Injury.

Spinal cord injury (SCI) often results in permanent functional loss due to the complexity of the post-SCI microenvironment, but the composition and functional dynamics of the post-SCI microenvironment remain poorly understood. We applied spatial metabolomics to detect metabolites within the spinal cord of SCI rats, revealing the existence of a high-uric acid (hUA) microenvironment. Subsequently, we utilized Bulk-RNA sequencing and single-cell RNA sequencing (scRNA-seq) analysis, identified elevated expression of Cellular communication network factor 1 (Ccn1) and alterations in purine metabolic patterns. To investigate the role of Ccn1 within this hUA microenvironment, PC12 cell line and Sprague-Dawley (SD) rats were used. In vitro, 4 groups were designed: Control (n = 6), UA (PC12 cells treated with 200 μM UA for 24 h) (n = 6), siCcn1 (Ccn1 knockdown using small interfering RNA) (n = 6), and siCcn1 + UA (n = 6). In vivo groups: SCI (spinal cord injury only) (n = 6), hUA (induced hUA microenvironment by gavage with oxonic acid potassium salt 750 mg/kg and and ethambutol 250 mg/kg) (n = 6), AAV (Ccn1 knockdown via adeno-associated virus) (n = 6), and AAV + hUA (n = 6). Results showed that UA significantly reduced cellular aerobic respiration levels (Control vs UA: 62.87 ± 16.76 vs 17.09 ± 4.91 pmol/min, P < 0.01) and induced pyroptosis, Ccn1 knockdown significantly improved aerobic respiration (siCcn1 + UA vs UA: 46.45 ± 12.54 vs 17.09 ± 4.91 pmol/min, P < 0.05) and reduced the level of pyroptosis. Total cellular ATP levels, the NAD⁺/NADH ratio, and proliferation capacity were also assessed. In vivo, Ccn1 knockdown significantly increased the Basso, Beattie, and Bresnahan (BBB) locomotor scores of animals on the 7 days post-injury (AAV + hUA vs hUA: 3.33 ± 0.52 vs 2.00 ± 0.63, P < 0.05) and reduced neuronal pyroptosis. The hUA microenvironment upregulated Ccn1 expression, suppressed aerobic respiration, induced pyroptosis, and disrupted purine metabolism, Ccn1 knockdown reversed these biological processes, suggesting its potential as a therapeutic target for SCI.