TNF and atrial fibrillation: Chronic damage to AF (e.g., age-related collagen degradation and repeated microinjury) leads to the release of inflammatory factors (e.g., IL-1β and TNF-α), matrix-degrading enzymes (e.g., MMPs) and the degradation of cartilage oligomeric matrix protein (COMP) [7], which accelerates the decomposition of IVD stroma (e.g., proteoglycans and collagen), increases type I collagen and decreases type II collagen, while the water content of AF and NP gradually decreases, the NP loses its elasticity, and cracks appear in the AF.