| Background:Lumbar disc degenerative disease is a common disease in spine surgery department. And lumbar disc herniation is the most common kind, with lower back pain and (or) lower limbs pain and anesthesia as the main clinical symptoms. According to statistics of the Ministry of Health, a total of more than200million patients with lumbar disc degenerative disease are now in China, where patients with lumbar disc herniation account for15.2%. And in recent years, it has shown an upward trend, expanding from the elder to the young at an alarming rate every year. Lumbar disc degeneration is considered to be the pathological basis of lumbar degenerative disease, which is manifested as the disc cells reduction and degradation of extracellular matrix (ECM). The latter is considered the direct cause of biomechanical properties changes of the disc, which finally leads to disc protrusion or extrusion, nerve root or spinal cord pressure, and the corresponding signs and symptoms. Pathogenesis of disc degeneration is not entirely cleared, but it is certain that disc degeneration is the result of multiple factors. In addition to the age, the abnormal expression of cytokines, genetic predisposition, biomechanical abnormalities and abnormal increased activity of matrix metalloproteinases (MMPs) are all involved in the pathological degeneration of the intervertebral disc. The abnormal increase of the MMPs activity is especially thought to play a key role in disc degeneration process. MMPs is a group of isozyme requiring Zn2()?, Ca2+and other metal ions as cofactors, which participates into the ECM degradation functions, and has played a role in reduction of extracellular and membrane component. It is the key enzyme that can degenerate almost all ECM components except polysaccharide. Since the first kind of MMPs found by Gross in1962,28members have been separated from the MMPs family which has been named as MMP-1-28in the order of discovery time. Normal disc tissue contains a small amount of MMPs, which maintains a certain ratio to the expression of tissue inhibitor of metalloproteinases (TIMPs), and keeps the dynamic equilibrium of synthesis and degradation of ECM. MMP-2and MMP-3are the important kinds of MMPs, which are considered as the key enzymes of intervertebral disc degeneration. Domestic and international researches show that, MMP-2and MMP-3expressions are significantly higher in degenerative intervertebral disc tissue, which is closely related to disc degeneration of intervertebral disc, however, the specific mechanisms for mediation remains unclear. The increased activities of MMP-2and MMP-3are adjusted by many factors. Moreover, autoregulation of MMPs is also an important adjusting manner. Foreign studies have shown that MMPs may be involved in waterfall autoregulation of MMPs. However no reports on correlation research about MMP-2and MMP-3have been found in China now. Magnetic resonance imaging (MRI) is the most common imaging of lumbar disc degeneration at present. Pfirrmann grading standard (Pfirrmann,2001) is the most acceptable grading standard with MRI detection as the basis, which has been widely used in clinical spinal surgery. Now, there is no research about the Pfirrmann grading expression of MMPs in different lumbar disc degenerations.Objective:1.To exploer the expression of matrix metalloproteinases-2(MMP2)、matrix metalloproteinases-3(MMP-3) in nucleus pulposus(NP) of different degenerative degree and normal lumbar intervertebral discs.2. Analysis the correlations between the expression of MMP-2and MMP-3in different stages of degenerated intervertebraldiscs3.To investigate the expression of MMP-2and MMP-3in different stages of degenerated intervertebraldiscs according to Pfirrmann standard.Methods:The tisssues of the degenerated NP were collected from40patients with lubar disc herniation who recived posterior lumbar interbody fusion and pedicle screw system internal fixation in the Department of NO.3Orthopaedics,Jingzhou Central Hospital from July2012to November2013.There were18male patients and22female patients with the age ranged from32to61years old,(41±2.4) years in average.The disc herniation located at L2,L3in1patient, L3,L4in2patients, L4,L5in17patients, L5,S1in20patients.40patients were divided into3groups according to the lumbar MRI:12patients in protrusion,18patients in extrusion and10patients in sequestration.The normal NP were collected10patients received a operation during the same period,due to lumbar vertebral fracture.There were6male patients and4female patients with the age from19to32years old,(24±1.6) years in average. The NP were obtained from L1,L2in5patient, L2,L3in4patients and L3,L4in1patients.All the operations do by one group surgeons who have plenty experiecce,the NP tissues were washed clearly by stroke-physiological saline solution after the operation and soaked in10%formalin for24hours,then do paraffin section in the pathology department,the sickness of the section was4um,each NP tissue was do6sections. All sections were saved in a refrigerator at4℃.After all the NP tissues were collected completely,HE staining and immunohistochemical staining method were used to observe the expression of MMP-2and MMP-3in normal and different degenerdtive degree of nucleus pulposus. The difference between degenerated and control NP,as well as the difference between the different degree of Pfirrmann grading system,were analyzed by one-way analysis of variance, the correlation of MMP-2and MMP-3in degenerative NP were analyzed by Pearson test.All the data were analyzed by Statistical Product and Service Solutions17.0software package for the significance test and the correlation analysis. The P<0.05experssed have significant difference.Results:1.HE staining results The control group:nucleus pulposus cells and cartilage-like cells were distributed in extracellular matrix.There were a lot of cells in nucleus pulposus,the cells were spindle or polygonal in shape,with clear outlines and rich cytoplasm.The degeneration group:nucleus pulposus cells and cartilage-like cells were distributed randomizedly in extracellular matrix,there were a few of long spindle cells, with vague outlines,large amount lysosomes were accumulated and laege vacuoles were found.2.Immunohistochemieal staining results MMP-2was sited at the cytoplasm, the positive result of the cartilage cell displayed the brown yellow or brown granules in the cytoplasm The positive expression rate of MMP-2in controlgroup, protrusion group, extrusion group and sequestration group were(7.94±2.55)%,(46.04±4.73)%,(83.43±3.51)%and (86.35±4.14)%respectively,with significant difference between the normal group and the degenerative group(P<0.01),but with no significant differencebetween the extrusion group and sequestrationgroup(P>0.05). The positive expression rate of MMP-3in controlgroup, protrusion group, extrusion group and sequestration group were (6.86±2.12)%,(29.55±7.40)%,(62.44±9.94)%and (77.59±6.92)%,there was significant difference among the different groups. The positive expression rate of MMP-2,MMP-3in Pfirrmann grading Ⅱ,Ⅲ,Ⅳ,Ⅴrespectively were (10.73±3.55)%,(53.37±10.62)%,(68.56±9.54)%,(84.26±6.48)%and (8.48±2.72)%,(34.37±6.99)%、(52.04±10.79)%,(67.43±9.74)%, there was significant difference among the different grade according to the result of LSD-t test.The Pfirrmann grading system was well consistent with the expression of MMP-2and MMP-3.the expression of the MMP-2and MMP-3in the degeneration of the intervertebral disc was positively correlated(r=0.604).Conclusion:1The expression of MMP-2, MMP-3in the degenerated nucleus pulposus is higher than that in the normal nucleus pulposus,which indicated that MMP-2, MMP-3may be closely involved in the process of lumbar intervertebral disc Degeneration.2There was significant difference among the different grade of the Pfirrmann grading system,which indicate the Pfirrmann grading system can well indirectly reflect degenerative degree of lumbar intervertebral disc.3The positive correlation of the expression of MMP-2and MMP-3,which indicat that MMP-2play a important role in the intervertebral disc degeneration maybe related to MMP-3. |
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