Serum Levels of TGF-beta1, TIMP-1 and TIMP-2 in Patients with Lumbar Spinal Stenosis and Disc Herniation

Study design: The serum levels of transforming growth factor-beta 1 (TGF-beta1), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and TIMP-2 were measured by enzyme-linked immunosorbent assay.

Purpose: To compare the serum levels of TGF-beta1, TIMP-1 and TIMP-2 between patients with lumbar spinal stenosis and disc herniation.

Overview of literature: It has been reported that increased concentrations of TGF-beta1, TIMP-1 and TIMP-2 in the ligamentum flavum might be a possible pathogenesis for ligamentum flavum hypertrophy in spinal stenosis. However, it is not determined whether this phenomenon in spinal stenosis is a local or systemic problem.

Methods: The concentrations of TGF-beta1, TIMP-1 and TIMP-2 were quantitatively analyzed by ELISA in the ligamentum flavum and serum of patients with lumbar spinal stenosis (n=16) and disc herniation (n=16). The thickness of ligamentum flavum was measured on axial T1-weigted magnetic resonance image. The biochemical and radiological results were compared for the two conditions.

Results: The thickness of the ligamentum flavum was larger in patients with spinal stenosis compared with that with disc herniation (p=0.001). The mean concentrations of TGF-beta1, TIMP-1, and TIMP-2 in the ligamentum flavum were significantly higher in patients with spinal stenosis than those with disc herniation (all, p < 0.05). However, the difference in serum levels of TGF-beta1 (p=0.464), TIMP-1 (p=0.146) and TIMP-2 (p=0.794) was not significant between the lumbar spinal stenosis and disc herniation patients.

Conclusions: Despite increased levels of TGF-beta1, TIMP-1, and TIMP-2 in the ligamentum flavum of spinal stenosis patients compared to disc herniation patients, the serum levels of TGF-beta1, TIMP-1 and TIMP-2 were very similar in both groups. These results indicate that the role of TGF-beta1, TIMP-1 and TIMP-2 on hypertrophy of the ligamentum flavum in spinal stenosis patients is a local phenomenon, not systemic.