Open Access Research

Human MMP28 expression is unresponsive to inflammatory stimuli and does not correlate to the grade of intervertebral disc degeneration

Marina Klawitter1, Lilian Quero1, Alessando Bertolo2, Marco Mehr2, Jivko Stoyanov2, Andreas G Nerlich3, Juergen Klasen4, Nikolaus Aebli6, Norbert Boos145 and Karin Wuertz15*

Author Affiliations

1 Spine Research Group, Competence Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Zurich, Switzerland

2 Swiss Paraplegic Research, Nottwil, Switzerland

3 Institute of Pathology, Academic Clinic Munich-Bogenhausen, Munich, Germany

4 University Hospital Balgrist, Zurich, Switzerland

5 AOSpine Research Network, Duebendorf, Switzerland

6 Swiss Paraplegic Center, Nottwil, Switzerland

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Journal of Negative Results in BioMedicine 2011, 10:9  doi:10.1186/1477-5751-10-9

Published: 29 July 2011

Abstract

Background

MMP28 (epilysin) is a recently discovered member of the MMP (matrix metalloproteinase) family that is, amongst others, expressed in osteoarthritic cartilage and intervertebral disc (IVD) tissue. In this study the hypothesis that increased expression of MMP28 correlates with higher grades of degeneration and is stimulated by the presence of proinflammatory molecules was tested. Gene expression levels of MMP28 were investigated in traumatic and degenerative human IVD tissue and correlated to the type of disease and the degree of degeneration (Thompson grade). Quantification of MMP28 gene expression in human IVD tissue or in isolated cells after stimulation with the inflammatory mediators lipopolysaccharide (LPS), interleukin (IL)-1β, tumor necrosis factor (TNF)-α or the histondeacetylase inhibitor trichostatin A was performed by real-time RT PCR.

Results

While MMP28 expression was increased in individual cases with trauma or disc degeneration, there was no significant correlation between the grade of disease and MMP28 expression. Stimulation with LPS, IL-1β, TNF-α or trichostatin A did not alter MMP28 gene expression at any investigated time point or any concentration.

Conclusions

Our results demonstrate that gene expression of MMP28 in the IVD is not regulated by inflammatory mechanisms, is donor-dependent and cannot be positively or negatively linked to the grade of degeneration and only weakly to the occurrence of trauma. New hypotheses and future studies are needed to find the role of MMP28 in the intervertebral disc.

Keywords:
MMP28; Epilysin; Matrix metalloproteinase; Intervertebral disc; Inflammation