Avaliação do estresse oxidativo na degeneração discal humana

Abstract

Introduction and Justification: Degenerative disc disease is one of the leading causes of low back pain, associated with multiple environmental, occupational, epigenetic, and genetic factors. Initial treatment is conservative, including medications, injections, and physiotherapy. Surgery is indicated only in refractory cases, symptomatic patients with clinical-radiological agreement. To understand the pathophysiology of the degenerative process, it is necessary to comprehend the mechanisms of cell death and regeneration. Oxidative stress has been studied as one of the main molecular factors inducing disc degeneration and has attracted researchers' interest due to its relationship with neurodegenerative diseases and biological factors associated with aging. Objectives: To evaluate oxidative stress in the human intervertebral disc in lumbar degenerative disease through protein, genetic, and biochemical markers to aid in understanding the role of oxidative stress in disc degeneration. Methods: Intervertebral disc samples were obtained from patients undergoing surgical treatment for lumbar spine disorders, divided into mild (Pfirrmann grades II and III) and severe (Pfirrmann grades IV and V) groups. The following analyses were performed: I - immunohistochemistry to assess the expression of antioxidant proteins TRX and PRDX/PAG1, II - RT-qPCR to verify the expression of genes NF-?B, GSK3ß, and P21/ CDKN1A, and III - Biochemical tests to quantify the sulfhydryl protein and determine nitric oxide production to ascertain oxidative stress levels. Results: TRX protein showed predominantly positive expression in chondrocytes and fibroblasts, with significantly higher expression in milder disease grades (75.32 ± 6.65) compared to the more severe ones (68.98 ± 8.25) (p < 0.001). PRDX/PAG1 exhibited higher expression in clusters of NP chondrocytes and in milder diseases (65.70 ± 12.15) (p < 0.001). All evaluated genes showed a tendency for increased expression in the most severe degrees of the disease and presented a positive Pearson statistical correlation, particularly the P21/ CDKN1A gene, which demonstrated genetic hyperexpression with significant statistical difference for the most severe degrees of pathology (p = 0.038). The sulfhydryl protein was more abundant in mild grades compared to severe grades of pathology (14.42 ± 6.37 vs. 7.52 ± 3.26, p = 0.009). The amount of nitric oxide produced was higher among those with severe degeneration compared to those with moderate degeneration (9.29 ± 2.55 vs. 8.02 ± 0.92, p = 0.290). Conclusions: Lumbar disc degeneration results from various factors, including mechanical, metabolic, inflammatory, and genotoxic stressors. According to this study, the most severe grades of this pathology (Pfirrmann Scale) occur due to reduced antioxidant activity (TRX, PRDX/PAG1, sulfhydryl proteins), increased expression of inflammatory and senescent genes (NF-kB, GSK3ß, P21/ CDKN1A), and elevated nitric oxide production, ultimately leading to cellular apoptosis. [resumo fornecido pelo autor]