Oral Presentation Matrix Biology Society of Australia and New Zealand Annual Meeting 2012

Peroxynitrite, a lesion oxidant, modulates endothelial cell-derived extracellular matrix in human atherosclerotic lesions (#30)

Christine Y Chuang 1 , Georg Degendorfer 1 , Astrid Hammer 2 , Ernst Malle 2 , John M Whitelock 3 , Michael J Davies 1 4
  1. The Heart Research Institute, Newtown, NSW, Australia
  2. Institute of Cell Biology, Histology and Embryology, Center for Molecular Medicine, Medical University of Graz, Graz, Austria
  3. Graduate School of Biomedical Engineering, The University of New South Wales, Kensington, NSW, Australia
  4. Faculty of Medicine, University of Sydney, Camperdown, NSW, Australia

The extracellular matrix (ECM) of the vascular basement membrane is vital for maintaining the functional and mechanical properties of arteries. Matrix components, including laminin, heparan sulfate (HS) proteoglycans, such as perlecan, interact with growth factors and enzymes to regulate endothelial and smooth muscle cell adhesion, proliferation and migration. These interactions are perturbed in atherosclerotic lesions, where activated monocytes and macrophages generate reactive oxidants, which alters the ECM composition. These changes contribute to endothelial cell dysfunction (an early and defining marker for atherosclerosis) and weakening of the mechanical properties of the artery, which is associated with plaque rupture, the major cause of most heart attacks and strokes.

The aim of this study was to investigate the effects of a putative lesion oxidant, peroxynitrite, on native ECM proteins, including laminin, perlecan, type IV collagen and fibronectin, synthesised by human coronary artery endothelial cells (HCAECs). We have previously shown that peroxynitrite damages the perlecan protein core and its HS chains, as shown by diminished fibroblast growth factor 2 binding and mediated proliferation. We now demonstrate that peroxynitrite damages HCAEC-derived native ECM components, which resulted in a loss of antibody recognition to perlecan, collagen IV and also to cell binding sites of native laminin and fibronectin. This loss of recognition was accompanied by decrease in HCAEC adhesion. Interestingly, versican gene expression was increased in HCAECs cultured on peroxynitrite-treated ECM as compared to HCAECs on tissue culture plates, consistent with alterations to ECM structure during lesion development. Furthermore, colocalisation of laminin and versican with 3-nitrotyrosine, a characteristic epitope generated by peroxynitrite, was detected in advanced human atherosclerotic lesions.

In conclusion, peroxynitrite modifies HCAEC-generated ECM by inducing structural and functional changes to matrix molecules, particularly perlecan and laminin, which are important in endothelial cell activity and function. These data suggest a mechanism through which oxidants, such as peroxynitrite, modify the arterial basement membrane in atherosclerotic lesions that may lead to lesion rupture.