Study On Expression Of GDF-5and BMPRâ…¡ Protein And Correlation With The Degree Of Disc Degeneration In Human Degenerative Discs And End-plate

Objective:To investigate the expression of GDF-5and BMPRIIin degenerative human IVDs and endplates And analyse the correlation with thehistological degeneration of discs and end-plates. Methods:（1）Thedegenerative endplate and disc tissue were harvested from24patientswho sufferred from lumbar degenerative disease，and the normal endplateand disc tissue were harvested from6patients who sufferred fromfracture of lumbar in our department.The degree of lumbar discdegenerative were preoperativly graded range level I to level V base onthe classification of Pfirrmann grading system.(2)Sections were taken forH&E staining to score the degree of morphological degeneration ofendplants and discs according to scoring system which Mankin andMaitre published previously. The degree of discs degeneration wereevaluated by Maitre’s criteria. The degree of endplates were scored byMankin’s criteria.(3) The expression of GDF-5and BMPRII within the30disc and endplate samples were tested by Immunohistochemistry(IHC).(4) Data was then presented as means±standard errors and itwas analysed with Single-factor analysis of variance. Result:(1) Thedegree of discs degeneration were evaluated by Maitre’s criteria. A scoreof0to3represents a histologically normal (non-degenerate) disc and there were11cases with0to3scored,4to8indicates moderatedegeneration and there were12cases with4to8scored,9to12indicated severe degeneration and there were7cases with9to12scored.The degree of endplates were scored by Mankin’s criteria. A score of0to4represents a histologically normal (non-degenerate) endplate and therewere8cases with0to4scored,5to10indicates moderate degenerationand there were15cases with5to10scored,11to14indicated severedegeneration and there were7cases with11to14scored.(2)Thepercentage of GDF-5of immune-positivity in NP area was62.09±10.04%in normal group，55.0±9.16%in moderate degenerative and56.71±2.43%in severe degenerative group respectively.The percentage of GDF-5ofimmune-positivity in AF area was33.27±7.36%in normal group，30.08±6.16%in moderate degenerative group and28.14±5.87%in severedegenerative group respectively. The percentage of BMPRII ofimmune-positivity in NP area was34.64±5.95%in normal group，38.75±7.02%in moderate degenerative group and6.43±3.37%in severedegenerative group. The percentage of BMPRII of immune-positivity inAF area was26.18±8.36%in normal group,29.67±6.41%in moderatedegenerative group，21.57±4.24%in severe degenerative grouprespectively.The expression of GDF-5and BMPRII was significanthigher in NP than in AF(P <0.05). The expression of GDF-5and BMPRIIwas observed in both the normal and degenerate discs and there was no statistical significance between normal and degenerate discs(P>0.05).(3)The percentage of GDF-5of immune-positivity in endplate close toNP area was63±5.26%in normal group，55.33±7.25%in moderatedegenerative group and46.43±6.65%in severe degenerative grouprespectively.The percentage of GDF-5of immune-positivity in endplateclose to AF area was16.88±6.22%in normal group，14.53±7.10%inmoderate degenerative group and10.86±7.80%in severe degenerativegroup respectively. The percentage of BMPRII of immune-positivity inendplate close to NP area was31.13±8.50%in normal group，35.07±7.41%in moderate degenerative group and34.14±4.85%in severedegenerative group respectively.The percentage of BMPRIIimmune-positivity in endplate close to AF area was5.0±6.52%in normalgroup，13.87±5.40%in moderate degenerative group and14.57±4.24%insevere degenerative group respectively.The expression of GDF-5andBMPRII was significant higher in the endplate close to NP area thanclose to AF area (P <0.05). The expression of GDF-5and BMPRII wasobserved in both the normal and degenerate endplate. The expression ofGDF-5in endplate was significant higher in normal group thandegenerate groups(P <0.05). The expression of BMPRII was no statisticalsignificance between normal and degenerate endplate(P>0.05).Conclusion:(1)The expression of GDF-5was found in both thenon-degenerate and degenerate lumbar endplate. There was a significantly decrease in the number of GDF-5was detected in degenerative endplatecompare with normal endplate which imply that GDF-5may play a roleto inhibit the degeneration of lumbar endplate.(2) GDF-5and its receptorBMPRII are mainly located in the central part of the lumbar endplate andless distributed around the endplate. It shows that GDF-5(Belong toBMPs family) mainly act on the center of endplate.(3)The GDF-5proteinis expressed in both the non-degenerate and degenerate discs whichshows GDF-5may involved in the normal matrix homeostasis in thehuman IVD. It’s also suggests that the pathogenesis of disc degenerationis not associated with a reduced expression of GDF-5.(4) The BMPRII indiscs and endplates is expressed in both the non-degenerative anddegenerative group and there was no statistical significance between thenon-degenerated and the degenerated one’s. It’s suggests that humanlumbar disc and endplate cells derived from degenerate discs retain theirability to respond to GDF-5.