Crosstalk between Autophagy and Apoptosis in Intervertebral Disc Degeneration

Objective: To describe the relationship between autophagy and apoptosis and the possible signaling pathways involved in degenerative lumbar intervertebral disc. Summary of Background Data: Autophagy and apoptosis are regulatory cellular mechanisms that determine many pathologies, including degenerative intervertebral disc disease. The interactions between these events in the damage or protection of intervertebral disc cells and in cellular homeostasis remain controversial. Methods: The sample size was twenty patients who underwent lumbar spine surgery for symptomatic disc herniation or spondylolisthesis. Intervertebral discs were classified by magnetic resonance as Pfirrmann grade IV and grade V. Six patients were operated on two levels, resulting in twenty-six intervertebral discs that were submitted to immunohistochemistry to verify the protein expression of autophagy and apoptosis markers. Results: The autophagic markers had greater protein expression in the human intervertebral disc (Pfirrmann Grades IV and V). Under these conditions, autophagy and apoptosis showed a negative correlation. Regarding apoptosis, caspase 8 presented the highest protein expression, which allows inferring the preference for the extrinsic pathway in cell death. Conclusions: Autophagy had the greatest protein expression negative profile compared to apoptosis. Caspase 8 had the highest protein expression in apoptosis.