HCMV infection of human vascular smooth muscle cells leads to enhanced expression of functionally intact PDGF β-receptor

Background: Cytomegaloviruses have been shown to promote atherogenesis in animal models. In humans, several epidemiological and clinical studies suggest involvement of the human cytomegalovirus (HCMV) in the development of atherosclerosis. HCMV is suspected to be associated with an enhanced restenosis rate and the occurrence of vasculopathies after solid organ transplantation. However, knowledge about the cellular and molecular bases of these findings is very limited. Methods and results: Human coronary artery smooth muscle cells (HCASMC) were successfully infected with HCMV in vitro. Infection of HCASMC with all HCMV strains analyzed resulted in a substantial upregulation of the beta-receptor of platelet-derived growth factor (PDGFR-beta) expression as demonstrated by immunohistochemistry, immunofluorescence, FACS, and Western blot analysis. The amount of PDGFR-beta protein present in HCASMC rapidly increased after 12 h of infection and this difference persisted for 72 It post-infection. We showed by quantitative FACS analysis that the extent of PDGFR-P upregulation differed significantly between the HCMV strains TB40E, Toledo, and AD169. The expression of insulin-like growth factor receptors as well as hepatocyte growth factor receptors, however, was downmodulated in HCMV-infected HCASMC. Most importantly, the HCMV-associated upregulation of PDGFR-beta protein resulted in functionally intact receptors. A significantly higher increase of proliferative activity following stimulation with PDGF-BB was observed in HCMV-infected HCASMC compared to the uninfected control. Conclusions: Our data suggest that HCMV directly activates the PDGF system, which could promote atherogenesis and restenosis by activation of smooth muscle cell proliferation and neointima formation. (c) 2005 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.