Objective: To investigate the role of transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) in pathogenesis and progression of human intervertebral disc degeneration by detecting the expressions of these two factors in different degrees of degenerative discs.
Methods: The lumbar intervertebral discs were collected from 33 patients with lumbar disc herniation and 12 patients with lumbar vertebral fracture between November 2012 and April 2013. All samples were observed under the microscope after HE staining, and then were divided into different subgroups according to the degenerative degree. The expressions of TGF-β1 and CTGF were detected by Western blot.
Results: According to the pathological features, 10 discs were defined as normal discs, 10 as mild degenerative discs, 9 as moderate degenerative discs, and 16 as severe degenerative discs. The histological observation showed that rounded nucleus pulposus cells with similar size evenly distributed in the cartilage-like matrix, and no hyperplastic collagenous fiber was seen in normal discs; mild degenerative discs characterized by slightly larger nucleus pulposus cells in the matrix, but cells did not decrease, a small quantity of inflammatory cells infiltrated in the matrix, hyperplasia of collagenous fiber was not seen; most of the nucleus pulposus cells became bigger, some showed a bulb form, the number of nucleus pulposus cells was significantly reduced, low grade hyperplasia of collagenous fiber emerged in the matrix, new vessels and inflammatory cells were both found in some specific areas of discs in moderate degenerative discs; there was no nucleus pulposus cells in the matrix of severe degenerative discs, the hyperplasia of collagenous fiber was obvious. The relative expression of TGF-β1 in 3 degeneration discs was significantly higher than that in normal discs (P < 0.05), and the expression of TGF-β1 was significantly higher in severe degenerative discs than in moderate and mild degenerative discs (P < 0.05), but no significant difference between moderate and mild degenerative discs (P > 0.05). The relative expression of CTGF in moderate and severe degeneration discs was significantly higher than that in normal discs (P < 0.05); and the expression of CTGF in mild degenerative discs was higher than that in normal discs, but there was no significant difference (P > 0.05); and significant difference in CTGF expression was found among 3 degeneration discs (P < 0.05).
Conclusion: The expressions of TGF-β1 and CTGF are closely related to the degree of human lumbar disc degeneration, these two factors may play an important role in promoting lumbar intervertebral disc degeneration.