Murine Norovirus Infection Variably Alters Atherosclerosis in Mice Lacking Apolipoprotein E

Macrophages play a key role in the development of atherosclerosis. Murine noroviruses (MNV) are highly prevalent in research mouse colonies and infect macrophages and dendritic cells. Our laboratory found that MNV4 infection in mice lacking the LDL receptor alters the development of atherosclerosis, potentially confounding research outcomes. Therefore, we investigated whether MNV4 likewise altered atherosclerosis in ApoE(-/-) mice. In the presence of oxidized LDL, MNV4 infection of ApoE(-/-) bone marrow-derived macrophages increased the gene expression of the inflammatory markers inducible nitric oxide synthase, monocyte chemoattractant protein 1, and IL6. In addition, proteins involved in cholesterol transport were altered in MNV4-infected ApoE -/- bone marrow-derived macrophages and consisted of increased CD36 and decreased ATP-binding cassette transporter A1. MNV4 infection of ApoE(-/-) mice at 12 wk of age (during the development of atherosclerosis) had a variable effect on atherosclerotic lesion size. In one study, MNV4 significantly increased atherosclerotic plaque area whereas in a second study, no effect was observed. Compared with controls, MNV4-infected mice had higher circulating Ly6C-positive monocytes, and viral RNA was detected in the aortas of some mice, suggesting potential mechanisms by which MNV4 alters disease progression. Plaque size did not differ when ApoE -/- mice were infected at 4 wk of age (early during disease development) or in ApoE -/- mice maintained on a high-fat, high-cholesterol diet. Therefore, these data show that MNV4 has the potential to exert a variable and unpredictable effect on atherosclerosis in ApoE(-/-) mice. We therefore propose that performing experiments in MNV-free mouse colonies is warranted.

Cardiac, aortic, and pulmonary arteriopathy in HIV-infected children: the Prospective P2C2 HIV Multicenter Study

Arteriopathy in human immunodeficiency virus (HIV)-infected patients is being increasingly recognized, especially in children. However, few studies have histologically evaluated the coronary arteries in HIV-infected children, and none have systematically assessed the aorta and pulmonary arteries. The coronary arteries, thoracic aorta, and the main and branch pulmonary arteries from the postmortem hearts of 14 HIV-infected children were systematically reviewed for vasculopathic lesions and compared with 14 age-matched controls. Findings from the HIV-infected children were compared with clinical, laboratory, and other postmortem findings. Coronary arteriopathy, seen in seven (50%) of the HIV-infected children, was primarily calcific, and it was associated with decreased CD3 and CD4 peripheral blood counts. Large vessel arteriopathy, seen in 9 (64%) of the 14 HIV-infected children, was primarily centered on the vasa vasorum and consisted mainly of medial hypertrophy and chronic inflammation. Large vessel lesions were associated with increased left ventricular mass z-scores (P = 0.02), and 78% of patients with large vessel arteriopathy had postmortem cardiomegaly. Coronary and large vessel arteriopathies are common in pediatric HIV-infection and have different clinicopathologic features suggesting different pathogenesis.

Low multiplicity cytomegalovirus infection of human aortic smooth muscle cells increases levels of major histocompatibility complex class I antigens and induces a proinflammatory cytokine milieu in the absence of cytopathology

BACKGROUND

Cytomegalovirus has been implicated in the development of allograft vasculopathy in heart transplant recipients. Given that allograft vasculopathy is a form of chronic rejection, it is conceivable that cytomegalovirus somehow alters the allogeneic response to the vasculature. Prior work has demonstrated that smooth muscle cells (SMCs) are highly permissive for cytomegalovirus and exhibit cytopathologic characteristics and alterations in MHC class I antigens in response to cytomegalovirus at a high multiplicity of infection (MOI).

METHODS

To determine whether cytomegalovirus at low, more clinically relevant MOI, can alter SMCs phenotypically, human aortic SMCs were infected with approximately 1 plaque forming units/3000 cells of cytomegalovirus strain AD169.

RESULTS

One week after infection, human aortic SMCs (compared with human foreskin fibroblasts) demonstrated no cytopathologic characteristics (n = 6), released reduced amounts of intact virion into the culture media (assessed by exposing naive monolayers of human foreskin fibroblasts to media and staining for cytomegalovirus immediate-early antigen, n = 3), yet had at least, if not greater detectable total cytomegalovirus vital DNA levels. Infected HASMCs uniformly increased their expression of MHC class I antigen by 55% +/- 21% above constitutive levels (assessed by flow cytometry (n = 5, p < 0.0001). Cytomegalovirus infection resulted in an increase in interleukin-6 mRNA expression compared to control (297 +/- 63 vs 188 +/- 50, respectively; p = 0.02, n = 6) and reduced the expression of transforming growth factor-beta mRNA (802 +/- 152 vs 1201 +/- 236, respectively; p = 0.05).

CONCLUSIONS

These data suggest that low MOI of cytomegalovirus can infect SMCs without producing cell cytolysis and, in spite of this lack of overt infection, modulate cell surface antigens and cytokine mRNA levels that can influence allogeneic responses.

Aortic endothelium in HIV-1 infection: chronic injury, activation, and increased leukocyte adherence

Clinical and serological studies provide evidence for a pathogenetically relevant vasculopathy in acquired immune deficiency syndrome (AIDS); however, the morphological status of the endothelium under conditions of human immunodeficiency virus (HIV)-1 infection is only sparsely documented. In this study we adapted an en face preparation technique of endothelium for use in immunohistochemistry and investigated the aortic endothelium of pre-AIDS and AIDS patients (n = 32) in comparison with an HIV-negative group (n = 17). The control group showed a regular pattern of evenly distributed aortic endothelial cells, whereas the endothelial cell pattern in the HIV-1-infected patients was clearly disturbed. Simultaneously, the degree of leukocyte adherence on the aortic endothelium increased significantly. These changes were accompanied by an up-regulation of the vascular cell adhesion molecule-1 (VCAM-1) and E-selectin (ELAM-1). The endothelium turnover increased, and one-half of the HIV-1-infected patients exhibited HLA-DR (major histocompatibility complex class II) antigen in the aortic endothelium. Our results provide evidence for a profound and repeated injury with regeneration and activation of the endothelium in HIV-1 infection. Injury as well as activation of the endothelium impairs its normal regulatory properties. This could have consequences for the maintenance of the blood-brain barrier; it might influence the immunologically important interaction of the endothelium with T cells; and it might trigger Kaposi's sarcoma.