Expression Of High Mobility Group Box-1 In The End-plate Of Degenerated Intervertebral Disc And Its Significance

Objective:To investigate High Mobility Protein Group Box-1's expression in the end-plate of degenerative intervertebral disc and its significance.Methods:1.Created animal model of intervertebral disc degeneration (IDD):Japanese White Rabbit was chose to be the laboratory animal.Injury models, including induction of spinal instability through facetectomy and resection of spinous processes and damaging annulus fibrosus with needle of defined gauges, were used in rabbit's lumbar to create IDD;2.Harvested samples:killed the rabbits at different time points, removed the intact affected discs as the experimental group, and non-affected lower thoracic discs as control group;3.Validated IDD:X-ray and MRI were taken to observe the radiography changes; tissue slices hematoxylin and eosin stain was of histology alternation; collagen type II and proteoglycane were measured by enzyme linked immunosorbent assay (ELISA) as the molecular biology evidence;4.Measured the objective protein:qualitative detected and semiquantitative analyzed the HMGB1 and NF-κB in discs with immunohistochemical and image analysis technics;Results:1.In comparing with the control group, the affected discs of experimental groups including anterior-stabbing annulus fibrosus and posterior-breaking spinal stability appeared height loss, water content loss, calcification of end-plate, osteophyte of adjacent vertebrae, architecture distortion of annulus fibrosus and nucleus pulposus, and cytoreduction. ELISA test showed both collagen typeⅡand proteoglycans'content of affected discs reduced in three different time point compared with control group(P<0.05),and anterior-stabbing disc group was more serious than posterior-breaking spinal stability group(P<0.05).2.Immunohistochemisty showed HMGB1 expressed in both control and experimental groups'discs, and HMGB1 positive was only detected in end-plate but not annulus fibrosus and nucleus pulposus.Expression of HMGB1 in the end-plate had an upward trend with the aggravation of disc degeneration.3.Immunohistochemisty showed NF-κB expressed in end-plate and nucleus pulposus of both control and experimental groups'discs, and its expression had a downward trend with the aggravation of disc degeneration.Conclusion:1.Both anterior-stabbing annulus fibrosus and posterior-breaking spinal stability could induce the degeneration of rabbit's disc;2.Anterior-stabbing annulus fibrosus could induce more serious degeneration of rabbit's disc than posterior one in the same period.3.HMGB1 expresses in both control and experimental groups' discs, but it was only detected in end-plate.4.The expression of HMGB1 in experimental group's discs is higher than control one, and had a upward trend with the aggravation of disc degeneration.5.HMGB1 may play a role in maintaining the chronic inflammation in rabbit's disc degenerating. However, it is not likely that HMGB1 induce the inflammation via the classic activation approach of NF-κB.