MMP1 and atrial fibrillation: IVD herniation involves alterations in the AF but also in the NP, including loss of proteoglycans and water content, upregulation of matrix metalloproteinases (MMP-1, -2, -3, -9, among others) and inflammatory mediators (tissue necrosis factor (TNF)-α, interleukin (IL)-1β, etc) that contribute to the weakening and mechanical failure of the disc tissue (Risbud and Shapiro, 2014).