Interleukin-1 production and cell-activation response to cytomegalovirus infection of vascular endothelial cells

Abstract

Human cytomegalovirus (HCMV) is a source of major complications in immunosuppressed individuals, and endothelial involvement in HCMV infection is well documented. Traditionally laboratory strains of HCMV have been used in experimental investigations in vitro; however the continuous propagation of these strains in fibroblasts have attenuated the virus making it unsuitable for infecting other cell systems such as endothelial cells. In this study a recent clinical isolate of HCMV was propagated through several passages in endothelial cells and was used to investigate the effect of HCMV infection of human umbilical vein endothelial cells (HUVEC) on IL-1 production and cell proliferation. Infection of HUVEC with the clinical isolate of HCMV (at multiplicity of infection 5:1) suppressed the production of IL-1 alpha (82%) and IL-1 beta (99%) at 5 h post infection; the levels returned to that of the control within 24h post infection. Ultraviolet inactivated (but not heat killed) virus produced similar suppression confirming that a thermolabile viral structural protein or intact virion were responsible for this suppression. Infection of HUVEC with the clinical isolate increased the number of these cells and the rate of their proliferation. An increase of infected HUVEC number under quiescent growth conditions continued as the infection progressed (6-10 days post infection), exhibiting, at 3 days post infection, 5 times the number of uninfected HUVEC (control) which did not tolerate the quiescent culture conditions for more than 4 days. Live virus is responsible for this increase because UV-inactivated virus did not maintain the proliferation of HUVEC. These studies suggest that while infection of HUVEC with a recent clinical isolate of HCMV suppressed the production of IL-1 at early hours after infection, it increased the proliferation of these cells at later stages of infection.

Human Cytomegalovirus Cell Tropism and Pathogenesis

“…IL-1 scrum levels were not elevated during HCMV infection after orthotopic liver transplantation [200], In situ hybridization analyses revealed that in HCMV-infected lungs, there was local expression of IL-1 in reactive macrophages and endothelial cells, whereas infected cells themselves did not express IL-1 [212], Con sistent with the latter finding are observations in infected endothelial cell cultures, demonstrating autocrine secre tion of IL-1 at late times after infection while the cytokine remained undetectable in the culture supernatant [62]. At early times after infection, IL-I levels in the supernatant of cultured endothelial cells even seem to be decreased [91], In transient expression systems, transfection of the IE1 gene led to upregulation of the IL-1 promoter in the lipopolysaccharide-stimulated monocytic cell line THP1 [213]. In infected cultured monocytes, an IL-1 upregula tion was accompanied, however, by a clear decrease in biologic IL-1 activity [214], An inhibitory factor, ex pressed together with IL-1.…”

Alterations in the Expression of ELAM‐1, ICAM‐1 and VCAM‐1 after In Vitro Infection of Endothelial Cells with a Clinical Isolate of Human Cytomegalovirus

“…The use of antibodies to inhibit the adhesion of leukocytes to cytokine-activated endothelial cells has been used regularly to characterize molecules involved in leukocyte-endothelial cell adhesion (2,8,26). However, to confirm the results of the adhesion inhibition assay, we used flow cytometric analysis to investigate the changes in the expression of these adhesion molecules on mock-and HCMV-infected HUVEC.…”

“…The supernatants were harvested and stored at -80 C until use. The virus-free supernatants were free of infectious virus when the production of CPE (at 14 days post challenge) and the presence of immediate-early/early antigen (at 24 hr post challenge), were investigated (26).…”

In vitro infection of aortic endothelial cells by caprine arthritis encephalitis virus enhances in vitro transmigration of peripheral blood leukocytes and modulates their phenotypic expression

“…In this system we have compared the effect on leukocyte adhesion of infecting aortic endothelial cells with CAEV with that of treatment with TNFa, an initiator of the sequence of events leading to expression of the endothelial cell surface molecules involved in leukocyte transmigration. Viral infection has frequently been shown to activate endothelial cells and thereby affect leukocyte adhesion, and the lentiviruses HIV and SIV are known to infect endothelial cells [1,15,27]. Activation of human endothelial cells by West Nile virus results in increased expression of MHC class II molecules and of adhesion molecules [24].…”