The integrins are a large family of molecules that control a variety of cell-to-cell and cell-to-outside world interactions. Their role appears to be more dynamic than the cadherins, which are simply adhesive in nature. Certain of the integrins control the adhesion of white blood cells to the lining of the blood vessels, while some others bind to inflammatory proteins involved in wound healing. Several integrins control the of laying down new blood vessel networks a process called angiogenesis. In growth and wound healing this process is switched on and off, while some tumors apparently have evolved a method to inhibit this signal.
Since many integrins have a binding site for epidermal growth factor in addition to a lectin binding site, and epidermal growth factor can be mimicked by the blood type A antigen. This may help explain why it has been reported that individuals who are blood type A have a much higher incidence of hemangiomas of the liver (benign tumors characterized by extravagant capillary networks of blood vessels.) Since many tumors shown to be more common in blood type A, such as tumors of the breast, are sensitive to treatments that involve inhibiting the tumors' ability to develop additional blood supplies (anti-angiogenesis) the effect of one's A antigen on such tumors would exert a profoundly negative effect.
Integrins are receptor proteins which are of crucial importance. They are the main way that cells both bind to and respond to the extra cellular matrix. They are part of a large family of cell adhesion receptors which are involved in cell-extracellular matrix and cell-cell interactions.
Integrins can adhere (bind) an array of ligands. Common ligands are for example fibronectin? and laminin?.
Adhesion antagonist by herbal medicines
Integrin anto-agonist: Crude ethanolic extract of the anti-rheumatic herbal drug gravel root (rhizome of Eupatorium purpureum), was identified as a potent inhibitor of ICAM-1 and some beta 1 and beta 2 integrin-mediated cell [Adhesion? adhesions]. “It appears that it has therapeutic potential for diseases where integrin adhesion molecules play a significant role.” (Planta Med 1998 Dec;64(8):683-5)
The active principle of gravel root has now been isolated and identified as Cistifolin (5-acetyl-6-hydroxy-2,3-dihydro-cis-2-isopropenyl-3- tiglinoyloxybenzofuran). Cistofolin appears to alter T cell production of the macrophage-attracting chemokines CCL3 and CCL4 which appear to alter expression of ICAM-1. cistifolin inhibits the Mac-1 (CD11b/CD18)-dependent monocyte adhesion to fibrinogen in a concentration-dependent manner.
Feverfew (parthenolide) also inhibits the expression of intercellular adhesion molecule-1 (ICAM-1) induced by the cytokines IL-1 and other integrin-mediated leucocyte adhesions.
1. Polysalov VN, Tarazov PG. [Blood group assignment--a genetic marker of hepatic hemangiomatosis]. Genetika 1992 Jul;28(7):161-4