Cytomegalovirus infection causes an increase of arterial blood pressure

Cytomegalovirus (CMV) infection is a common infection in adults (seropositive 60–99% globally), and is associated with cardiovascular diseases, in line with risk factors such as hypertension and atherosclerosis. Several viral infections are linked to hypertension, including human herpes virus 8 (HHV-8) and HIV-1. The mechanisms of how viral infection contributes to hypertension or increased blood pressure are not defined. In this report, the role of CMV infection as a cause of increased blood pressure and in forming aortic atherosclerotic plaques is examined. Using in vivo mouse model and in vitro molecular biology analyses, we find that CMV infection alone caused a significant increase in arterial blood pressure (ABp) (p<0.01∼0.05), measured by microtip catheter technique. This increase in blood pressure by mouse CMV (MCMV) was independent of atherosclerotic plaque formation in the aorta, defined by histological analyses. MCMV DNA was detected in blood vessel samples of viral infected mice but not in the control mice by nested PCR assay. MCMV significantly increased expression of pro-inflammatory cytokines IL-6, TNF-α, and MCP-1 in mouse serum by enzyme-linked immunosorbent assay (ELISA). Using quantitative real time reverse transcriptase PCR (Q-RT-PCR) and Western blot, we find that CMV stimulated expression of renin in mouse and human cells in an infectious dose-dependent manner. Co-staining and immunofluorescent microscopy analyses showed that MCMV infection stimulated renin expression at a single cell level. Further examination of angiotensin-II (Ang II) in mouse serum and arterial tissues with ELISA showed an increased expression of Ang II by MCMV infection. Consistent with the findings of the mouse trial, human CMV (HCMV) infection of blood vessel endothelial cells (EC) induced renin expression in a non-lytic infection manner. Viral replication kinetics and plaque formation assay showed that an active, CMV persistent infection in EC and expression of viral genes might underpin the molecular mechanism. These results show that CMV infection is a risk factor for increased arterial blood pressure, and is a co-factor in aortic atherosclerosis. Viral persistent infection of EC may underlie the mechanism. Control of CMV infection can be developed to restrict hypertension and atherosclerosis in the cardiovascular system.

Cytomegalovirus (CMV) infection is associated with cardiovascular diseases. The exact mechanisms, however, remain to be defined. Using both mouse model and cell culture analyses, we find that CMV infection alone causes an increase in blood pressure. Additionally, CMV infection augments the increased blood pressure induced by a high cholesterol diet. CMV infection alone, however, does not cause atherosclerosis in aortas. CMV infection along with a high cholesterol diet, however, causes the classic atherosclerotic plaque formation in the main artery connected to the heart. Further studies show that CMV infection induces renin and angiotensin II (Ang II) expression in blood and in vessel cells, in a persistent infection manner. An increased expression of renin and Ang II has been known to cause an increase in blood pressure or hypertension in humans. Expression of viral genes and viral persistent infection of blood vessel endothelial cells resulting in an increased expression of inflammatory cytokines, including renin and Ang II, may underpin the molecular mechanism by which CMV infection induces an increase in blood pressure.