Figure 1.

ROS-mediated mechanisms in apical tissue breakdown. ROS induce apical tissue breakdown by causing molecular damage or disrupted cell signaling. Besides structural damage of cell and/or extracellular matrix components (DNA, protein, and lipids), the former mechanisms include the oxidative modification of matrix-degrading enzymes, such as, matrix metalloproteinase (MMP) and inhibition of their tissue inhibitors (TIMPs). Among the later mechanisms, ROS inhibit osteoblast differentiation, stimulate receptor activator nuclear factor κB (RANKL)-mediated osteoclast differentiation and activation, MMP expression and activity, and pro inflammatory response. OBLs, Osteoblats; LTs, lymphocytes; PMN, polymorphonuclear leukocytes; Mϕ, macrophages; OCls, osteoclasts; PLs, plasma cells.