title: Inhibiting IL-1 signaling pathways to inhibit catabolic processes in disc degeneration.
abstract: Intervertebral disc degeneration is characterized by an imbalance between catabolic and anabolic signaling, with an increase in catabolic cytokines particularly IL-1β, a key regulator of IVD degeneration. This study aimed to investigate intracellular signaling pathways activated by IL-1β, and GDF-5 in the degenerate IVD to identify potential new therapeutic targets. Human NP cells were cultured in alginate beads to regain in vivo phenotype prior to stimulation with IL-1β or GDF-5 for 30 min, a proteasome profiler array was initially utilized to screen activation status of 46 signaling proteins. Immunoflourescence was used to investigate activation of the NFκB pathway. Cell-based ELISAs were then deployed to confirm results for ERK1/2, p38 MAPK, c-jun, and IκB signaling. IHC was utilized to investigate native activation status within human IVD tissue between grades of degeneration. Finally, cells were stimulated with IL-1β in the absence or presence of p38 MAPK, c-jun, JNK, and NFκB inhibitors to investigate effects on MMP3, MMP13, IL-1β, IL-6, and IL-8 mRNA expression. This study demonstrated three key signaling pathways which were differentially activated by IL-1β but not GDF-5; namely p38 MAPK, c-jun, and NFκB. While ERK 1/2 was activated by both GDF-5 and IL-1. Immunohistochemistry demonstrated p38 MAPK, c-jun, and NFκB were activated during human IVD degeneration and inhibition of these pathways reduced or abrogated the catabolic effects of IL-1β, with inhibition of NFκB signaling demonstrating most widespread inhibition of IL-1β catabolic effects. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:74-85, 2017.
authors.affiliation: Biomolecular Sciences Research Centre, Sheffield Hallam University, S1 1WB, Howard Street, Sheffield, South Yorkshire, Sheffield, United Kingdom.
authors.forename: Jodie
authors.initials: J
authors.lastname: Daniels
authors.affiliation: Biomolecular Sciences Research Centre, Sheffield Hallam University, S1 1WB, Howard Street, Sheffield, South Yorkshire, Sheffield, United Kingdom.
authors.forename: Abbie A L
authors.initials: AA
authors.lastname: Binch
authors.affiliation: Biomolecular Sciences Research Centre, Sheffield Hallam University, S1 1WB, Howard Street, Sheffield, South Yorkshire, Sheffield, United Kingdom.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Le Maitre
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D055428:Growth Differentiation Factor 5 / Q000378:metabolism*; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism*; D007403:Intervertebral Disc / Q000378:metabolism*; D058990:Molecular Targeted Therapy; D061251:Primary Cell Culture; D015398:Signal Transduction
chemical_list: D053674:Aggrecans; C525893:GDF5 protein, human; D055428:Growth Differentiation Factor 5; C508585:IL1B protein, human; D053583:Interleukin-1beta
keywords: GDF-5; NFκB; interleukin 1; intervertebral disc; intracellular signaling