Leukocytes produce
oxidants at inflammatory sites, including within the artery wall during the development of
atherosclerosis. Developing lesions contain high numbers of activated leukocytes that generate
reactive nitrogen species, including
peroxynitrite/
peroxynitrous acid (ONOO-/ONOOH), as evidenced by the presence of oxidized/nitrated molecules including extracellular matrix (ECM)
proteins. ECM materials are critical for arterial wall integrity, function, and determine cell phenotype, with smooth muscle cells undergoing a phenotypic switch from quiescent/contractile to proliferative/synthetic during disease development. We hypothesized that ECM modification by ONOO-/ONOOH might drive this switch, and thereby potentially contribute to
atherogenesis. ECM generated by primary human coronary artery smooth muscle cells (HCASMCs) was treated with increasing ONOO-/ONOOH concentrations (1-1000 μM). This generated significant damage on
laminin,
fibronectin and
versican, and lower levels on
collagens and
glycosaminoglycans, together with the increasing concentrations of the damage
biomarker 3-nitrotyrosine. Adhesion of naïve HCASMC to ECM modified by 1 μM ONOO-/ONOOH was enhanced, but significantly diminished by higher ONOO-/ONOOH treatment. Cell proliferation and metabolic activity were significantly enhanced by 100 μM ONOO-/ONOOH pre-treatment. These changes were accompanied by increased expression of genes involved in mitosis (
PCNA, CCNA1, CCNB1), ECM (LAMA4, LAMB1, VCAN, FN1) and
inflammation (IL-1B, IL-6, VCAM-1), and corresponding
protein secretion (except VCAM-1) into the medium. These changes induced by modified ECM are consistent with HCASMC switching to a synthetic/proliferative/pro-inflammatory phenotype, together with ECM remodelling. These changes model those in
atherosclerosis, suggesting a link between
oxidant-modified ECM and
disease progression, and highlight the potential of targeting
oxidant generation as a therapeutic strategy.