Gene Expression Profiling Identifies Interferon Signalling Molecules and IGFBP3 in Human Degenerative Annulus Fibrosus

Low back pain is a major cause of disability especially for people between 20 and 50 years of age. As a costly healthcare problem, it imposes a serious socio-economic burden. Current surgical therapies have considerable drawbacks and fail to replace the normal disc in facilitating spinal movements and absorbing load. Therefore, the focus of regenerative medicine is on identifying biomarkers and signalling pathways to improve our understanding about the cascades of disc degeneration and allow for the design of specific therapies. We hypothesized that comparing microarray profiles from degenerative and non-degenerative discs will lead to the identification of dysregulated signalling and pathophysiological targets. Microarray data sets were generated from human annulus fibrosus cells and analysed using IPA ingenuity pathway analysis system. Gene expression values were validated by qRT-PCR, and respective proteins were identified by immunohistochemistry. Microarray analysis revealed 17 dysregulated molecular markers and various dysregulated cellular functions, including cell proliferation and inflammatory response, in the human degenerative annulus fibrosus. The most significant canonical pathway induced in degenerative annulus fibrosus was found to be the interferon signalling pathway. In conclusion, this study indicates interferon-alpha signalling pathway activation with IFIT3 and IGFBP3 up-regulation which may affect cellular function in human degenerative disc. 48 samples of intervertebral disc tissue - annulus fibrosus and nucleus pulposus - displaying varying degrees (grades) of degeneration