Serum Levels of TGF-β1, 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.