Degenerated human intervertebral discs contain autoantibodies against extracellular matrix proteins

Abstract

Degeneration of intervertebral discs (IVDs) is associated with back pain and elevated levels of inflammatory cells. It has been hypothesised that discogenic pain is a direct result of vascular and neural ingrowth along annulus fissures, which may expose the avascular nucleus pulposus (NP) to the systemic circulation and induce an autoimmune reaction. In this study, we confirmed our previous observation of antibodies in human degenerated and posttraumatic IVDs cultured in vitro. We hypothesised that the presence of antibodies was due to an autoimmune reaction against specific proteins of the disc. Furthermore we identified antigens which possibly trigger an autoimmune response in degenerative disc diseases. We demonstrated that degenerated and post-traumatic IVDs contain IgG antibodies against typical extracellular proteins of the disc, particularly proteins of the NP. We identified IgGs against collagen type II and aggrecan, confirming an autoimmune reaction against the normally immune privileged NP. We also found specific IgGs against collagens types I and V, but not against collagen type III. In conclusion, this study confirmed the association between disc degeneration and autoimmunity, and may open the avenue for future studies on developing prognostic, diagnostic and therapymonitoring markers for degenerative disc diseases.

Extraction of RNA from tough tissues with high proteoglycan content by cryosection, second phase separation and high salt precipitation

“…In our study, bovine NP tissue could not be homogenized by an electric ceramic pestle and mortar system. However, there were some studies which reported the use of homogenizer for extraction of RNA from NP tissues ( Table 2) [17][18][19][20][21]. Only two out of the five studies have mentioned the types homogenizers used.…”

“…Simple pestle and mortar systems may be a less expensive option. Capossela et al used a stainless steel mortar to pulverize human NP and AF tissue on dry ice [18] but the size and type of mortar was not mentioned precisely. In our attempts to homogenize the bovine NP tissue by a pestle and mortar system, it was difficult to pulverize the tissue as the bovine NP tissue from an adult animal was hard yet not brittle when frozen.…”

“…The studies reported by other groups used column based kits for RNA extraction [17][18][19][20][21]. Tang et al extracted RNA from rat NP and AF for cDNA microarray analysis and RT-qPCR.…”

Intervertebral Disc Degeneration and Low Back Pain: Molecular Mechanisms and Stem Cell Therapy

“…(115)(116)(117)(118) The aforementioned evidence shows that many different influences are at work in old and DD, including genetic inheritance, impaired metabolite transport, altered levels of enzyme activity, cell senescence and death, changes in matrix macromolecules and water content, structural failure, and neurovascular ingrowth. (6) LBP is related to ageing, mechanical stresses (119) and genetic predisposition (120), and it is attributed to DD in around 40% of patients (121,122). It appears that alteration in biomechanical properties of the disc structure, sensitization of nerve endings by release of chemical mediators, and neurovascular ingrowth into the degenerated discs all may contribute to the development of pain.…”

Technique and method development for intervertebral disc (IVD) research

“…Simple pestle and mortar systems may be a less expensive option. Capossela et al used a stainless steel mortar to pulverize human NP and AF tissue on dry ice [142] but the size and type of mortar was not mentioned precisely. In our experience, the frozen NP tissue is rather hard and tough, which is difficult to be broken by brutal force.…”