Autophagy Is a Protective Response to the Oxidative Damage to Endplate Chondrocytes in Intervertebral Disc: Implications for the Treatment of Degenerative Lumbar Disc

Oxid Med Cell Longev. 2017:2017:4041768. doi: 10.1155/2017/4041768. Epub 2017 Feb 22.

Abstract

Low back pain (LBP) is the leading cause of disability in the elderly. Intervertebral disc degeneration (IDD) was considered as the main cause for LBP. Degeneration of cartilaginous endplate was a crucial harmful factor during the initiation and development of IDD. Oxidative stress was implicated in IDD. However, the underlying molecular mechanism for the degeneration of cartilaginous endplate remains elusive. Herein, we found that oxidative stress could induce apoptosis and autophagy in endplate chondrocytes evidenced by western blot analysis, flow cytometry, immunofluorescence staining, GFP-LC3B transfection, and MDC staining. In addition, we also found that the apoptosis of endplate chondrocytes was significantly increased after the inhibition of autophagy by bafilomycin A1 shown by flow cytometry. Furthermore, mTOR pathway upstream autophagy was greatly suppressed suggested by western blot assay. In conclusion, our study strongly revealed that oxidative stress could increase autophagy and apoptosis of endplate chondrocytes in intervertebral disc. The increase of autophagy activity could prevent endplate chondrocytes from apoptosis. The autophagy in endplate chondrocytes induced by oxidative stress was mTOR dependent. These findings might shed some new lights on the mechanism for IDD and provide new strategies for the treatments of IDD.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Autophagy* / drug effects
  • Cells, Cultured
  • Chondrocytes / cytology
  • Chondrocytes / drug effects
  • Chondrocytes / metabolism
  • Hydrogen Peroxide / toxicity
  • Intervertebral Disc / metabolism*
  • Intervertebral Disc Degeneration / metabolism
  • Intervertebral Disc Degeneration / pathology*
  • Macrolides / toxicity
  • Male
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Motor Endplate / cytology
  • Oxidative Stress / drug effects
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • TOR Serine-Threonine Kinases / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • LC3 protein, rat
  • Macrolides
  • Microtubule-Associated Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • bafilomycin A1
  • Hydrogen Peroxide
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases