Angiogenesis in Oral Lichen Planus: A Comparative Study with Lesions of Different Degrees of Aggressiveness

Angiogenesis, the process by which new vessels are formed from pre-existing vascular structures, is controlled by numerous growth factors and pro-angiogenic cytokines, as well as by various endogenous inhibitors of neovascularization. under physiological situations, these activators and inhibitors are in balance, but in pathological situations there can be persistent or excessive activation of pro-angiogenic agents [1]. Vascular endothelial growth factor (VEGF) is one of the most potent and known stimulators of angiogenesis, showing the ability to induce vascular permeability [2], besides the proliferation and migration of endothelial cells, essential steps for the development of new blood vessels [3]. Other growth factors essential for vascular formation are the angiopoietins (ANG), among which ANG-1 and ANG-2 are the most known and best characterized [4]. In contrast to VEGF, angiopoietins are angiogenic mediators whose action does not induce mitotic activity in endothelial cells [5]. Despite their biological activities not being completely elucidated, it is known that ANG-1 is constantly secreted in situations of vascular quiescence, as well as during the process of vascular maturation, a later step in angiogenesis [5,6]. Besides, ANG-1 acts as an anti-inflammatory cytokine [4]. On the other hand, ANG-2, despite showing affinity for the same Tie-2 receptor of ANG-1, does not phosphorylate it, thus exerting an antagonistic effect of ANG-1 [4], destabilizing the vascular endothelium, which causes the regression of neoformed vessels and apoptosis in endothelial Crimson Publishers Wings to the Research Research Article