title: Autophagy attenuates the catabolic effect during inflammatory conditions in nucleus pulposus cells, as sustained by NF-κB and JNK inhibition.
abstract: Proteoglycan degradation contributing to the pathogenesis of intervertebral disc (IVD) degeneration is induced by inflammatory cytokines, such as tumor necrosis factor‑α (TNF‑α) and interleukin‑1β (IL‑1β). Cell autophagy exists in degenerative diseases, including osteoarthritis and intervertebral disc degeneration. However, the autophagy induced by TNF‑α and IL‑1β and the corresponding molecular mechanism appear to be cell‑type dependent. The effect and mechanism of autophagy regulated by TNF‑α and IL‑1β in IVDs remains unclear. Additionally, the impact of autophagy on the catabolic effect in inflammatory conditions also remains elusive. In the present study, autophagy activator and inhibitor were used to demonstrate the impact of autophagy on the catabolic effect induced by TNF‑α. A critical role of autophagy was identified in rat nucleus pulposus (NP) cells: Inhibition of autophagy suppresses, while activation of autophagy enhances, the catabolic effect of cytokines. Subsequently, the autophagy‑related gene expression in rat NP cells following TNF‑α and IL‑1β treatment was observed using immunofluorescence, quantitative polymerase chain reaction and western blot analysis; however, no association was present. In addition, nuclear factor κB (NF‑κB), c‑Jun N‑terminal kinase (JNK), extracellular signal‑regulated kinases and p38 mitogen‑activated protein kinase inhibitors and TNF‑α were used to determine the molecular mechanism of autophagy during the inflammatory conditions, and only the NF‑κB and JNK inhibitor were found to enhance the autophagy of rat NP cells. Finally, IKKβ knockdown was used to further confirm the effect of the NF‑κB signal on human NP cells autophagy, and the data showed that IKKβ knockdown upregulated the autophagy of NP cells during inflammatory conditions.
authors.affiliation: Experimental Center of the Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Kang
authors.initials: K
authors.lastname: Xu
authors.affiliation: Department of Orthopedics, The Second People's Hospital of Guangdong Province, Guangzhou, Guangdong 510080, P.R. China.
authors.forename: Weijian
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Anjing
authors.initials: A
authors.lastname: Liang
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Huang
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Chunhai
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Spinal Surgery, Sun Yat‑sen Memorial Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ye
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000473:pathology; D053583:Interleukin-1beta / Q000276:immunology*; D007403:Intervertebral Disc / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000276:immunology* / Q000473:pathology; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000276:immunology*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000276:immunology*; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D053583:Interleukin-1beta; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D048670:MAP Kinase Kinase 4