A role for TNFα in intervertebral disc degeneration: A non-recoverable catabolic shift
2013
Purmessur, D. | Walter, B.A. | Roughley, P.J. | Laudier, D.M. | Hecht, A.C. | Iatridis, James
This study examines the effect of TNFα on whole bovine intervertebral discs in organ culture and its association with changes characteristic of intervertebral disc degeneration (IDD) in order to inform future treatments to mitigate the chronic inflammatory state commonly found with painful IDD. Pro-inflammatory cytokines such as TNFα contribute to disc pathology and are implicated in the catabolic phenotype associated with painful IDD. Whole bovine discs were cultured to examine cellular (anabolic/catabolic gene expression, cell viability and senescence using β-galactosidase) and structural (histology and aggrecan degradation) changes in response to TNFα treatment. Control or TNFα cultures were assessed at 7 and 21days; the 21day group also included a recovery group with 7days TNFα followed by 14days in basal media. TNFα induced catabolic and anti-anabolic shifts in the nucleus pulposus (NP) and annulus fibrosus (AF) at 7days and this persisted until 21days however cell viability was not affected. Data indicates that TNFα increased aggrecan degradation products and suggests increased β-galactosidase staining at 21days without any recovery. TNFα treatment of whole bovine discs for 7days induced changes similar to the degeneration processes that occur in human IDD: aggrecan degradation, increased catabolism, pro-inflammatory cytokines and nerve growth factor expression. TNFα significantly reduced anabolism in cultured IVDs and a possible mechanism may be associated with cell senescence. Results therefore suggest that successful treatments must promote anabolism and cell proliferation in addition to limiting inflammation.
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