Intervertebral disc and endplate cells response to IL-1β inflammatory cell priming and identification of molecular targets of tissue degeneration
1 IRCCS Istituto Ortopedico Galeazzi, Orthopaedic Biotechnology Lab, Milan, Italy
2 Department of Orthopaedics, UHealth Sports Medicine Institute, University of Miami, Miller School of Medicine, Miami, FL, USA
3 Ospedale Galliera, Laboratorio di Istocompatibilità/IBMDR, Genoa, Italy
4 IRCCS Istituto Giannina Gaslini, Laboratorio di Genetica Umana, Genoa, Italy
5 IRCCS Ospedale Policlinico San Martino, Lung Cancer Unit, Genoa, Italy
6 Diabetes Research Institute and Cell Transplant Centre, University of Miami, Miller School of Medicine, Miami, FL, USA
7 IRCCS Istituto Ortopedico Galeazzi, Scoliosis Unit, Department of Orthopaedics and Traumatology-Spine Surgery III, Milan, Italy
Abstract
Inflammation represents an important factor leading to metabolic imbalance within the intervertebral disc (IVD), conducive to degenerative changes. Therefore, a thorough knowledge of the IVD and endplate (EP) cell behaviour in such pathological environments is essential when designing regenerative therapeutic strategies. The present study aimed at assessing the molecular response of the IVD constitutive nucleus pulposus (NPCs)-, annulus fibrosus (AFCs)- and endplate (EPCs)-derived cells to interleukin (IL)-1β treatment, through large-scale, high-throughput microarray and protein analysis, identifying the differentially expressed genes and released proteins. Overall, the inflammatory stimulus downregulated stemness genes while upregulating pro-inflammatory, pro-angiogenic and catabolic genes, including matrix metalloproteases, which were not balanced by a concomitant upregulation of their inhibitors. Upregulation of anti-inflammatory and anabolic tumour necrosis factor inducible gene 6 protein (TNFAIP6), of IL-1 receptor antagonist (IL-1Ra) (at gene and protein levels) and of trophic insulin-like growth factor 1 (IGF1) was also observed in all cell types; IGF1 particularly in AFCs. An overall inhibitory effect of tumour necrosis factor alpha (TNFα) signal was observed in all cell types; however, EPCs showed the strongest anti-inflammatory behaviour. AFCs and EPCs shared the ability to limit the activation of the signalling mediated by specific chemokines. AFCs showed a slightly senescent attitude, with a downregulation of genes related to DNA repair or pro-mitosis.Results allowed for the identification of specific molecular targets in IVD and EP cells that respond to an inflammatory environment. Such targets can be either silenced (when pathological targets) or stimulated to counteract the inflammation.
Graphical Abstract

Keywords
- Intervertebral disc cells
- endplate cells
- interleukin 1 beta
- gene array
- protein array
- inflammation markers
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