Cytomegalovirus- and interferon-related effects on human endothelial cells. Cytomegalovirus infection reduces upregulation of HLA class II antigen expression after treatment with interferon-γ
ABSTRACT Cultured human umbilical vein endothelial cells (HUVEs) were infected with human cytomegalovirus (HCMV) strain AD169. Up to 50% HUVEs proved to be positive for HCMV early nuclear antigens 24 hours after inoculation with virus. Following infection kinetics of surface expression of HLA class I and II, intercellular adhesion molecule (ICAM-1) and endothelial lymphocyte adhesion molecule (ELAM-1) on HUVEs were investigated by means of flow cytometry. A slight increase in HLA class I expression was observed, whereas expression of HLA class II (DR, DP, DQ) antigens was not induced by infection with HCMV. Furthermore, when compared with uninfected cells treated with interferon-gamma (IFN-gamma), reduced enhancement of HLA-DR expression was conspicuous in HCMV-infected cells treated with IFN-gamma. There is evidence that only a portion of HUVE is affected in its ability to upregulate HLA class II antigens. While expression of ICAM-1 was found to be enhanced between 8 and 20 hours after infection with a maximum at 12 hours after infection, no modulation of ELAM-1 was seen.
- SourceAvailable from: Vladimir Muzykantov
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- "P-selectin is typically regulated through cellular sorting: this adhesion molecule is intracellularly stored in endothelial cells in Weibel-Palade bodies, which are rapidly exocytosed and secrete P-selectin to the plasma membrane upon activation by agonists such as cytokines, thrombin, or ROS  . E-selectin is absent in endothelial cells under normal conditions, however it is synthesized de novo within a few hours in response to inflammatory mediators such as interleukins (ILs), tumor necrosis factor (TNF)-α, or endotoxins      . The strictly inducible nature of selectin exposure on the endothelial lumen limits their utility for targeting resting endothelium, yet supports the notion that selectins can be utilized as targets in pathologically altered endothelial cells. "
ABSTRACT: The endothelium represents an important therapeutic target for containment of oxidative stress, thrombosis and inflammation involved in a plethora of acute and chronic conditions including cardiovascular and pulmonary diseases and diabetes. However, rapid blood clearance and lack of affinity to the endothelium compromise delivery to target and restrict medical utility of antioxidant enzymes (e.g., catalase) and fibrinolytics. The use of "stealth" PEG-liposomes prolongs circulation, whereas conjugation with antibodies to endothelial determinants permits targeting. Constitutive endothelial cell adhesion molecules (CAM, such as ICAM-1 and PECAM-1, which are stably expressed and functionally involved in oxidative stress and thrombosis) are candidate determinants for targeting of antioxidants and fibrinolytics. CAM antibodies and compounds conjugated with anti-CAM bind to endothelial cells and accumulate in vascularized organs (preferentially, lungs). Pathological stimuli enhance ICAM-1 expression in endothelial cells and facilitate targeting, whereas PECAM-1 expression and targeting are stable. Endothelial cells internalize 100-300 nm diameter conjugates possessing multiple copies of anti-CAM, but not monomolecular antibodies or micron conjugates. This permits size-controlled sub-cellular targeting of antioxidants into the endothelial interior and fibrinolytics to the endothelial surface. Targeting catalase to PECAM-1 or ICAM-1 protects endothelial cells against injury by oxidants in culture and alleviates vascular oxidative stress in lungs in animals. Anti-CAM/catalase conjugates are active for a few hours prior to lysosomal degradation, which can be delayed by auxiliary drugs. Conjugation of fibrinolytics to monovalent anti-ICAM permits targeting and prolonged retention on the endothelial surface. Therefore, CAM targeting of antioxidants and fibrinolytics might help to contain oxidative and thrombotic stresses, with benefits of blocking CAM. Avenues for improvement and translation of this concept into the clinical domain are discussed.Current Pharmaceutical Design 02/2005; 11(18):2383-401. · 3.29 Impact Factor
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- "sion in infected endothelial cells (Scholz et al., 1992; Sedmak et al., 1994). Though IFN␤ may play some role in HCMV-mediated inhibition of endothelial cell MHC class II expression, direct infection also appears to result in inhibition of MHC class II expression (Scholz et al., 1992; Sedmak et al., 1995, 1994). Long-term infection of M with HCMV also results in decreased MHC class II expression (Fish et al., 1996). "
ABSTRACT: Macrophage (Mφ) activation, as measured by cell surface expression of MHC class II, was examined during infection of immunocompetent and immunocompromised mice with murine cytomegalovirus (MCMV). Intraperitoneal infection of CB17 SCID mice with 106PFU of MCMV elicited a large population of Mφ which expressed low levels of MHC class II. This was surprising since infection of SCID mice with lower doses (e.g., 104PFU) of MCMV elicits Mφ expressing high levels of MHC class II (M. T. Heise and H. W. Virgin,J. Virol.(1995) 69, 904–909).In vivoadministration of recombinant mouse IFNγ resulted in high levels of MHC class II expression on Mφ from control but not MCMV-infected SCID mice, suggesting that MCMV infection generates a state in which IFNγ is not effective at activating Mφ. The effect of MCMV infection was MHC class II specific, since MHC class I and ICAM-1 levels were increased on Mφ expressing low levels of MHC class II. Interference with IFNγ action was not due to productive or abortive infection of Mφ. This suggested that MCMV infection induces a soluble factor that alters Mφ responsiveness to IFNγ. Infection of SCID mice with 106PFU of MCMV induced higher levels of serum IFNαβ (one candidate for inhibition of IFNγ induction of MHC class II expression) than infection with 104PFU. We therefore evaluated the role of MCMV-induced IFNαβ on IFNγ responses of bone marrow-derived (BMMφ) or thioglycollate-elicited Mφin vitro.Infection of normal Mφ with MCMV at a low m.o.i. (0.1 to 0.2) impaired IFNγ-mediated induction of Mφ MHC class II expression, but not MHC class I expression. Inhibition of IFNγ responses was not observed in Mφ from mice with a null mutation in the IFNαβ receptor (IFNαβR−/−). To test thein vivorelevance of virus-induced IFNαβ to IFNγ-mediated responses, the kinetics of MHC class II induction during MCMV infection of IFNαβR−/− mice was evaluated. MCMV-infected IFNαβR−/− mice mounted an earlier Mφ MHC class II response than normal mice. We conclude that MCMV infection specifically impairs IFNγ-mediated MHC class II expression on Mφ and that induction of IFNαβ is one mechanism by which this inhibition occurs.Virology 02/1998; 241(2-241):331-344. DOI:10.1006/viro.1997.8969 · 3.28 Impact Factor