Abstract
Introduction: Several small leucine-rich proteoglycans (SLRPs) are involved in the regulation of collagen fibril size(s) in a variety of different soft and hard musculosk-eletal tissues. In the intervertebral disc (IvD) the major SLRPs involved in regulation of types I & II collagen fibril size are believed to be decorin, fibromodulin and lumican. Research into IvD degeneration and backpain is hampered by a lack of specific biomarkers to detect and monitor the disease process. We have discovered that two keratan sulphate (KS) substituted members of the SLRP family, Keratocan and Lumican (that are major KS-pro-teoglycans found in cornea) were unusually expressed in extracts from degenerative disc tissues.
Methods: Non-degenerate disc tissue (n=10) was obtained from 2 scoliosis patients and degenerate disc tissue from 11 patients undergoing surgery. The degenerate discs were graded using criteria described by Pfir-rman et al (Spine26: 1873; 2001). Tissue samples were extracted with 4M guanidine HCl and after dialysis subjected to SDS-PAGE and Western blot analyses using monoclonal antibodies that recognise epitopes on kera-tocan and lumican.
Results & Discussion: Keratocan was not found in the non-degenerate disc tissue but was present in all degenerate IvD tissues tested. Lumican showed and increased expression in extracts of degenative IvD tissues. Our working hypothesis is that the increased expression of these two SLRPs in degenerative disc tissue results from a reparative depostion of a type I collagen fibrillar ‘scar’. This unusual expression suggests their potential as biomarkers for detecting the onset of degenrative disc disease.
Correspondence should be addressed to Ms Alison McGregor, c/o BOA, SBPR at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
