The EP anchors the NP-AF complex to the vertebral bodies.133 In a healthy state, the NP is rich in proteoglycan-based extracellular matrix (ECM), which is predominantly composed of type II collagen and aggrecan in a homeostatic state maintained by NP cells.134 Pathologically, IVDD involves dysregulated ECM metabolism and cellular dysfunction within both the AF and NP compartments, ultimately leading to chronic low back pain, particularly among the elderly population135 (Fig. 4). Here, ACAN is linked to atrial fibrillation.