Introduction: Intervertebral disc degeneration (IDD) is one of the major causes of low back pain (LBP) which seriously affects health and normal physical activity. Recombinant human tumor necrosis factor-a (TNF-a) induced protein 6 (rhTSG-6) has been reported to have therapeutic effects on a variety of inflammatory diseases, but the effect and mechanism of rhTSG-6 action in IDD are not fully understood. The present study was aimed to explore the functional role of rhTSG-6 in interleukin (IL)-1b-induced nucleus pulposus (NP) cell model.
Materials and methods: Experimental human NP cells were isolated from the patients with idiopathic scoliosis and treated with culture medium containing IL-1b (10 ng/mL) for 24 hours to induce extracellular matrix degradation and apoptosis, simulating an IDD model in vitro. The viability of NP cells was analyzed by the CCK-8 assay. The relevant mRNA and protein levels were measured by RT-qPCR and western blot. The apoptosis of NP cells was determined by flow cytometry analysis and western blot.
Results: Compared with the NP cells without IL-1b treatment, IL-1b caused approximately 70% reduction in the viability of NP cells, while RhTSG-6 partly increased the decrease of IL-1b on cell viabilities. Moreover, treatment with rhTSG-6 considerably attenuated the upregulation of extracellular matrix (ECM)-catabolic factors (MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5), and increased the downregulation of ECM-anabolic factor (collagen II) in NP cells induced by IL-1b, indicating that ECM degradation was suppressed. Furthermore, rhTSG-6 also protected NP cells from IL-1b-induced apoptosis. Mechanically, rhTSG-6 inhibited the activation of members of mitogen-activated protein kinase (MAPK) pathway by blocking the phosphorylation of p38, c-Jun N-terminal kinase (JNK) and ERK in IL-1b-induced NP cells.
Conclusions: RhTSG-6 can attenuate ECM degradation and apoptosis in IL-1b-induced NP cells by inhibiting the p38, JNK and ERK pathways, which may contribute to its potential application in the therapy of IDD.
Keywords: IL-1β; apoptosis; extracellular matrix degradation; intervertebral disc degeneration; nucleus pulposus cells; rhTSG-6.