Matrix Metalloproteinases in Venous Tissue Remodeling and Varicose Vein Formation

Joseph   D.   Raffetto; Raouf   A.   Khalil

Abstract

Matrix metalloproteinases (MMPs) play a major role in extracellular matrix (ECM) turnover under both physiological and pathological conditions. Studies on venous tissues from experimental animals and humans identified several MMP subtypes, and showed significant changes in the expression and activity of specific MMPs during vein wall remodeling. Also, significant research has focused on the role of MMPs in chronic venous disease (CVD) and varicose vein formation in the lower extremities and their progression to thrombophlebitis and venous leg ulcer. Several hypotheses have been forwarded regarding the pathophysiological mechanisms underlying the relation between MMPs and the formation, progression and complications of varicose veins. The effects of MMPs on ECM degradation could result in significant venous tissue remodeling and degenerative and structural changes in the vein wall, leading to venous dilation and valve dysfunction. MMPs may also induce early changes in the endothelium and venous smooth muscle function in the absence of significant ECM degradation or structural changes in the vein wall. In addition, evidence suggests increased activity of MMPs in the advanced stages of chronic venous insufficiency (CVI) associated with skin changes and leg ulceration as well as in the wound fluid environment. Several pharmacological therapies and surgical strategies are being utilized in the management of varicose veins, with variable success and recurrence rates. Inhibition of MMPs may represent a novel therapeutic intervention to limit the progression of varicose veins to CVI and leg ulceration.

Keywords: Matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases, extracellular matrix, endothelium, smooth muscle, fibroblasts, varicose veins, chronic venous insufficiency, leg ulcers