A20 Regulates Inflammation Through Autophagy Mediated by NF-κB Pathway in Human Nucleus Pulposus Cells and Ameliorates Disc Degeneration In vivo

Intervertebral disc degeneration (IDD) is closely related to loss of the extracellular matrix (ECM), apoptosis and inflammation in nucleus pulposus cells (NPCs). It has been reported that Zinc finger protein A20/TNFAIP3 (A20) can inhibit the activity of the NF-κB pathway and promote autophagy. Therefore, we speculated that A20 can regulate inflammation and ameliorate IDD through autophagy mediated by NF-κB in human NPCs. Our results indicated that the expression of A20 and inflammatory factors in IDD tissues was increased. A20 is an essential negative regulator in the NF-κB pathway. Constructed adenoviral shRNA and overexpression vectors for A20 could effectively regulate the inflammation, autophagy, and activity of NF-κB, which in turn affected the progression of IDD. Inhibition of NF-κB on the basis of knocking down A20 results in increased autophagy, suggesting that A20-regulated autophagy was mediated by NF-κB. In vivo, A20 overexpression could ameliorate the progression of IDD and promote autophagy at the same time, while deletion of A20 leads to low levels of autophagy and severe degeneration. In summary, A20 plays an important role in inhibiting inflammation through autophagy mediated by NF-κB in NPCs and ameliorating IDD.