Expression of phosphorylated p38 MAPK in nucleus pulposus of degenerated cervical intervertebral disc / 第二军医大学学报

ABSTRACT

Objective: To observe the pathological changes of nucleus pulposus (NP) in cervical spondylosis patients and the expression of phosphorylated p38 mitogen activated protein kinase(p-p38 MAPK) in NP with the progression of cervical disc degeneration, in an attempt to explore the mechanism behind cervical disc degeneration. Methods NP specimens were collected from 35 patients with cervical spondylosis, who received surgical treatment during October 2008 to May 2009 in our hospital. The preoperative MRI (T2-weighted midsagittal images) information of all patients was obtained. The 35 cases included 25 males and 10 females, with an age range of 27-82 years. Five specimens were from a single space, 18 from two spaces, and 12 from three spaces; 4 specimens were from C3/4, 12 from C4/5,14 from C5/6, and 5 from C6/7. Nineteen specimens were used for pathology and immunohistochemistry study and 16 for Western blotting analysis. The degrees of disc degeneration were assessed by MRI grading system for cervical intervertebral disc degeneration. The pathological changes of NP of different degeneration grades and the location of p-p38 MAPK in NP were observed, and the relationship between the p-p38 MAPK and the degrees of MRI degeneration was analyzed. Results: With the aggravation of discs degeneration, the collagen fibers within NP were increased, thickened, and degraded, forming clusters, and the NP gradually became fibrotic. Phosphorylated p38 MAPK located in the cell nucleus of NP tissues. The positive rate of p-p38 MAPK increased gradually with the aggravation of degeneration, and the expression degrees of p-p38 MAPK (negative, weakly positive, strongly positive) were significantly different between groups of different degeneration degrees(P<0.05). A linear relationship was found between p-p38 MAPK expression and the degeneration degrees of cervical disc; Y = 0.423X-0.675 (P<0.05). Conclusion: Normal tissues are gradually replaced by fibrotic tissues in degenerated NP. Phosphorylated p38 MAPK is located in the cell nucleus of NP cells; the p-p38 MAPK plays important roles in the cervical intervertebral discs degeneration. Expression of phosphorylated p38 MAPK in NP increases with the aggravation of degeneration, suggesting that activation of p38 MAPK signaling pathway may be one of the mechanisms for cervical disc degeneration.