Increased Elastin-Degrading Activity and Neointimal Formation in Porcine Aortic Organ Culture

Abstract

We investigated the association between tissue elastolytic activity and the development of neointimal formation using a previously described porcine aortic organ culture. Neointimal formation is associated with the presence of intact endothelium (nondenuded cultures) but is markedly reduced if endothelial cells are removed (denuded cultures). In nondenuded organ cultures, elastolytic activity assessed by using [3H]elastin increased sixfold at day 3 after initiation of the culture (P < .01), a time earlier than the previously published increase in intimal smooth muscle cells (ISMCs). Elastolytic activity did not increase from day 3 to day 7 despite doubling of ISMCs but did double by day 14 (P < .01) and remained elevated to day 28, correlating with increases in ISMCs. In denuded organ cultures, elastolytic activity was much lower than in nondenuded organ cultures at day 3 (P < .05) but increased fivefold in the presence of nondenuded organ culture conditioned medium (P < .01). Addition of alpha 1-proteinase inhibitor for 14 days caused a 60% decrease in elastolytic activity in nondenuded organ cultures and a 27% reduction in ISMCs compared with untreated controls (P < .05 for both). The elastolytic activity, resolved as lytic bands on an elastin substrate gel, reflected candidate enzymes, one at 76 kD and perhaps a doublet at 43 and 50 kD. Our study suggests that endothelial cells release a soluble agent that enhances elastin-degrading activity in the aorta and may at least partially account for the initiation of neointimal formation.

Elastase and matrix metalloproteinase inhibitors induce regression, and tenascin-C antisense prevents progression, of vascular disease

“…In this study we adapted an organ culture system used previously to show the development of a neointima in porcine aorta in association with SMC proliferation (35). Those studies showed that the mechanism of SMC proliferation is likely related to serine elastase activity (11). Serine elastases are known to stimulate SMC proliferation by releasing growth factors such as FGF-2 from ECM proteoglycans (10).…”

“…Inhibitors were chosen to target MMPs or the heightened elastase activity demonstrated in Mctinduced vascular disease (8,18,21,22). Doses were based upon our previous studies (11,18,23).…”

The endogenous vascular elastase that governs development and progression of monocrotaline-induced pulmonary hypertension in rats is a novel enzyme related to the serine proteinase adipsin.

“…We have shown increased activity of a serine elastase of similar molecular weight in coronary arteries of piglets after experimental induction of the postcardiac transplant arteriopathy (29). Increased activity of a serine elastase is also present in aorta organ culture in association with the development of neointimal formation (30). In the clinical setting, increased elastolytic activity has also been described in atherosclerosis (11) and in a vasculopathy induced by actinic radiation (31 ).…”

Serum Elastase Activity, Serum Elastase Inhibitors, and Occurrence of Carotid Atherosclerotic Plaques

“…The results of theses studies suggest that release of elastase activity, in a porcine aortic organ culture model, was associated with intimal smooth muscle cell proliferation and intimal hyperplasia. 20 In this model, the inhibition of elastase activity with ␣ 1 -proteinase inhibitor markedly repressed the proliferation of neointimal smooth muscle cells. 20 Elastase inhibitors might also prevent the development of coronary artery disease experimentally induced after heart transplantation and intimal hyperplasia after balloon angioplasty in rabbits.…”

“…20 In this model, the inhibition of elastase activity with ␣ 1 -proteinase inhibitor markedly repressed the proliferation of neointimal smooth muscle cells. 20 Elastase inhibitors might also prevent the development of coronary artery disease experimentally induced after heart transplantation and intimal hyperplasia after balloon angioplasty in rabbits. 21,22 Several Japanese studies have been investigated the effects on atherosclerosis of an oral drug containing porcine pancreatic elastase 1.…”