MMP expression and its clinical significance in intervertebral disc destruction of spinal tuberculosis, Brucellar spondylitis, and pyogenic spondylitis.

Objective: This study is designed to investigate the roles of MMP-2, MMP-9, and MMP-13 in intervertebral disc destruction resulting from different types of spinal infections and their correlations with clinical quantitative data.

Methods: Disc tissue samples were collected from 60 patients with spinal infections (20 cases each of STB, BS, and PS in the infection group) and 20 patients with intervertebral disc herniation (control group). The expressions of MMP-2, MMP-9, and MMP-13 were detected by RT-qPCR. Correlation analysis was carried out with clinical quantitative data such as preoperative erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin (PCT), and related blood routine indicators in the infection group.

Results: In the analysis between the infection group and the control group, MMP-13 was expressed in the diseased intervertebral disc tissue of STB patients, but the result was not statistically significant (P = 0.2172). There was a significant difference in the expression of MMP-13 in the diseased intervertebral discs of BS and PS patients. The expressions of MMP-9 and MMP-2 were markedly increased in the diseased intervertebral disc tissue of STB, BS, and PS patients (all P < 0.05). In the inter-group analysis of the infection group, the expression of MMP-13 in the diseased intervertebral disc tissue of PS patients was significantly different from that of STB and BS (P < 0.0001), while there was no significant difference between the STB and BS groups (P = 0.2393). The expression of MMP-9 in the diseased intervertebral disc tissue of STB patients was significantly different from that of BS and PS (P < 0.0001), but there was no statistically significant difference between the BS and PS groups (P = 0.9643). There was no statistically significant difference in the expression of MMP-2 among the STB, BS, and PS groups. In the correlation analysis with clinical quantitative data, MMP-13 was positively correlated with CRP, ESR, IL-6, WBC, and NEUT levels (r values were 0.7346, 0.3465, 0.3326, 0.6347, and 0.5152 respectively), and negatively correlated with LYM level (r = -0.5152, P < 0.05), and had no correlation with PCT and MXD levels. MMP-9 was positively correlated with ESR level (r = 0.3412, P < 0.05) and had no correlation with CRP, IL-6, PCT, WBC, NEUT, and LYM levels. MMP-2 was positively correlated with NEUT and LYM levels (r values were 0.3021 and 0.3306 respectively, P < 0.05) and had no correlation with ESR, CRP, IL-6, PCT, and WBC levels.

Conclusion: MMP-2, MMP-9, and MMP-13 play crucial roles in intervertebral disc destruction due to spinal infections. The differential expression of MMPs may be one of the reasons for the varying degrees of intervertebral disc destruction in different types of spinal infections. Moreover, when clinical indicators such as CRP, ESR, IL-6, WBC, and NEUT increase, it suggests that the expression of MMP-13 in the intervertebral disc at the lesion site significantly rises, and it may become a new target for the treatment of spinal infections in the future.