Attenuation of cytomegalovirus-induced endothelial intercellular adhesion molecule-1 mRNA/protein expression and T lymphocyte adhesion by a 2'-O-methoxyethyl antisense oligonucleotide

Relation of high cytomegalovirus antibody titres to blood pressure and brachial artery flow-mediated dilation in young men: the Cardiovascular Risk in Young Finns Study

Human cytomegalovirus (CMV) infection is associated with a higher risk of cardiovascular disease in immunocompromised organ transplant patients. It has been linked with the pathogenesis of elevated arterial blood pressure. However, controversy exists as to whether CMV infection is associated with endothelial function, and little is known about its role as a potential risk factor for early atherosclerosis development at a young age. We aimed to discover if CMV antibody titres are associated with early vascular changes (carotid intima-media thickness, carotid artery distensibility and brachial artery flow-mediated dilation), blood pressure elevation or other traditional cardiovascular risk factors. CMV antibody titres were measured in 1074 women and 857 men (aged 24-39 years) taking part in the Cardiovascular Risk in Young Finns study. CMV antibody titres were significantly higher in women compared to men. In men, high CMV antibody titres were associated directly with age (P < 0·001) and systolic (P = 0·053) and diastolic (P = 0·002) blood pressure elevation, and associated inversely with flow-mediated dilation (P = 0·014). In women, CMV antibody titres did not associate with any of the analysed parameters. In a multivariate regression model, which included traditional atherosclerotic risk factors, CMV antibody titres were independent determinants for systolic (P = 0·029) and diastolic (P = 0·004) blood pressure elevation and flow-mediated dilation (P = 0·014) in men. High CMV antibody titres are associated independently with blood pressure and brachial artery flow-mediated dilation in young men. This association supports the hypothesis that common CMV infection and/or an immune response to CMV may lead to impaired vascular function at a young age.

Cytomegalovirus infection leads to microvascular dysfunction and exacerbates hypercholesterolemia-induced responses

Cytomegalovirus (CMV) persistently infects more than 60% of the worldwide population. In immunocompetent hosts, it has been implicated in several diseases, including cardiovascular disease, possibly through the induction of inflammatory pathways. Cardiovascular risk factors promote an inflammatory phenotype in the microvasculature long before clinical disease is evident. This study determined whether CMV also impairs microvascular homeostasis and synergizes with hypercholesterolemia to exaggerate these responses. Intravital microscopy was used to assess endothelium-dependent and -independent arteriolar vasodilation and venular leukocyte and platelet adhesion in mice after injection with either mock inoculum or murine CMV (mCMV). Mice were fed a normal (ND) or high-cholesterol (HC) diet beginning at 5 weeks postinfection (p.i.), or a HC diet for the final 4 weeks of infection. mCMV-ND mice exhibited impaired endothelium-dependent vasodilation versus mock-ND at 9 and 12 weeks and endothelium-independent arteriolar dysfunction by 24 weeks. Transient mild leukocyte adhesion occurred in mCMV-ND venules at 7 and 21 weeks p.i. HC alone caused temporary arteriolar dysfunction and venular leukocyte and platelet recruitment, which were exaggerated and prolonged by mCMV infection. The time of introduction of HC after mCMV infection determined whether mCMV+HC led to worse venular inflammation than either factor alone. These findings reveal a proinflammatory influence of persistent mCMV on the microvasculature, and suggest that mCMV infection enhances microvasculature susceptibility to both inflammatory and thrombogenic responses caused by hypercholesterolemia.

Allograft rejection-related gene expression in the endothelial cells of renal transplantation recipients after cytomegalovirus infection

OBJECTIVE

To explore the effects of cytomegalovirus (CMV) infection on rejection-related gene expression in the endothelial cells of renal transplantation recipients.

METHODS

Endothelial cells (ECs) were cultured and stimulated by a variety of factors: A, normal control group; B, inactivated human cytomegalovirus (HCMV) infection group; C, HCMV infection group; D, HCMV supernatant infection group; and E, ganciclovir HCMV group. Expression of intercellular adhesion molecule-1 (ICAM-1) and major histocompability complex (MHC) class I and class II antigens was detected by flow cytometry (FCM) and immunohistochemistry.

RESULTS

We found characteristic CMV-infected ECs in this study. There were no significant differences among groups A, B and D (P>0.05). Although the expression levels of ICAM-1 were not significantly different between groups C and E (P>0.05), the ICAM-1 expression in these two groups was significantly higher than that in group A (P<0.05). ICAM-1 expression was detected in groups C and E, while there was no expression in groups A, B and D. Furthermore, there was no significant difference of ICAM-1 mRNA expression between groups C and E (P>0.05). Human leucocyte antigen (HLA)-ABC expression was detected in all the groups, while HLA-DR expression was only detected in groups C and E. There were no significant differences of HLA-ABC and HLA-DR expression among groups A, B and D (P>0.05). However, the HLA-ABC and HLA-DR expression levels in groups C and D were higher than those of the remaining groups previously reported (P<0.05). Meanwhile, the HLA-ABC and HLA-DR expression levels in group E were lower than those of group C (P<0.05).

CONCLUSION

CMV could up-regulate the expression levels of ICAM-1 and MHC antigens, which was closely related to allograft rejection.

Brothers in arms: DNA enzymes, short interfering RNA, and the emerging wave of small-molecule nucleic acid-based gene-silencing strategies

The past decade has seen the rapid evolution of small-molecule gene-silencing strategies, driven largely by enhanced understanding of gene function in the pathogenesis of disease. Over this time, many genes have been targeted by specifically engineered agents from different classes of nucleic acid-based drugs in experimental models of disease to probe, dissect, and characterize further the complex processes that underpin molecular signaling. Arising from this, a number of molecules have been examined in the setting of clinical trials, and several have recently made the successful transition from the bench to the clinic, heralding an exciting era of gene-specific treatments. This is particularly important because clear inadequacies in present therapies account for significant morbidity, mortality, and cost. The broad umbrella of gene-silencing therapeutics encompasses a range of agents that include DNA enzymes, short interfering RNA, antisense oligonucleotides, decoys, ribozymes, and aptamers. This review tracks current movements in these technologies, focusing mainly on DNA enzymes and short interfering RNA, because these are poised to play an integral role in antigene therapies in the future.

The Association Between Cytomegalovirus Infection and Atherosclerotic Events in Renal Transplant Recipients

Cytomegalovirus (CMV) infection is a risk factor for arteriosclerosis in renal transplant recipients. We sought to investigate the effects of CMV infection on atherosclerotic events (AE) in renal transplant recipients. This retrospective analysis included 200 patients: 52 women and 148 men of overall mean age of 36.18 +/- 10.23 years who were transplanted at our center between 1998 and 2001. We analyzed demographic features, dialysis duration, diabetes, blood pressure level, body mass index (BMI), medications, and lipid parameters. CMV infection was diagnosed in 23.5% of patients in the first 2 years after transplantation; these patients were followed for 4 years. All patients had been assessed for AE, including previous myocardial infarction, angina, revascularization procedures, intermittent claudication, stroke, or transient ischemic attack. AE occurred in 13% during the follow-up period. CMV infection was more frequent among these patients compared to those without AE, namely 42.3% versus 20.6%, respectively. Although the gender, dialysis duration, serum cholesterol level, presence of acute rejection, and BMI were not associated with AE, age, hypertension, and CMV infection did show a relation. A multivariate analysis by logistic regression revealed mean age and CMV infection to be independent risk factors for AE: odds ratio (OR)=5.6, 95% confidence interval (CI)=1.3 to 24.6 (P=0.02) and OR=4, 95% CI = 1.3 to 12.3 (P=.01). This study suggested that the presence of CMV infection may be a triggering factor for AE in renal transplant recipients.

A multiparametric flow cytometry method for detection of modifications of antigen expression in polymorphonuclear cells infected by human cytomegalovirus

Human cytomegalovirus (CMV) has been shown to alter adhesion molecule expression on permissive cells such as endothelial cells. The aim of the present study was to investigate expression of receptors for these molecules on CMV infected polymorphonuclear leukocytes (PMNLs). CMV-induced variations on cellular integrin expression were examined using an in vitro system to obtain infected PMNLs. A triparametric flow cytometry approach was developed, which allows combined detection, in a single experiment, of both viral intranuclear antigen in the selected PMNLs and cellular CD11/CD18 expression. Comparison of infected PMNLs with uninfected cells showed a decrease of up to 50% in the expression of CD11b, CD11c, and CD18. This study thus demonstrates that the presence of CMV in PMNLs, which characterizes active infection, modifies the expression of integrins and may thus affect cell-to-cell interactions and immune functions.

The role of viruses in cardiac allograft vasculopathy

Considerable evidence suggests a role for viruses in transplant arteriosclerosis (TA), including observational data, experimental models and therapeutic trials implicating human cytomegalovirus (HCMV) in the progression to TA. In pediatric heart transplant patients, adenoviral genome in endomyocardial biopsies (EMB) is an important predictor of TA and graft loss. During CMV viremia, EMBs from adult patients demonstrate endothelialitis and vascular smooth muscle cell proliferation. These changes are predictors of subsequent diffuse TA. HCMV immediate early proteins (IE-1 and IE-2) increase the constitutive expression of intercellular adhesion molecule-1 (ICAM-1) independent of other intracellular cytokines. Likewise, viral chemokines such as US28 have been implicated in vascular disease because of their ability to induce smooth muscle cell migration. Recent data suggests that CMV might accelerate TA through its ability to abrogate the vascular protective effects of the endothelium-derived nitric oxide system (eNOS). Confirmation of causality requires clinical trials demonstrating that antiviral agents such as ganciclovir inhibit TA. Such studies in patients though limited to retrospective analyses, suggest that ganciclovir prophylaxis early after heart transplantation reduces the risk of TA. These observations emphasize the need for randomized controlled clinical trials to confirm a causal role for CMV (and other viruses) in TA.

Cardiac allograft vasculopathy: central role of endothelial injury leading to transplant "atheroma"

Endothelial injury plays a central role in the pathophysiologic mechanisms underlying cardiac allograft vasculopathy (CAV). Although the accelerated course of CAV and its localization to the allograft support an important role for the alloimmune response, there is considerable evidence implicating lipoprotein abnormalities, metabolic disturbances, viral infections, and systemic inflammation in the process. This multifactorial basis for CAV may be put into a pathophysiologic context in which endothelial cell injury is the triggering event that initiates and drives the proliferative and fibrotic processes characteristic of CAV. In the transplant setting, endothelial cell injury is induced by multiple factors, including brain death, ischemia-reperfusion, alloimmune responses, and viral infections. Once initiated, propagation of the proliferative processes that ultimately lead to vascular occlusion is enhanced by the abnormal metabolic environment of elevated lipoproteins and insulin resistance encountered in most patients. This review examines the evidence for the role of potential triggers of endothelial injury in the pathophysiology of CAV and discusses the central role of the nitric oxide pathway in the disease process.

Cardiac allograft vasculopathy and dysregulation of the NO synthase pathway

Cardiac allograft vasculopathy is the most aggressive form of atherosclerosis in humans and is the leading cause of death after the first year of heart transplantation. Endothelial dysfunction is a major contributing factor to the acceleration of coronary vascular disease in these individuals. A reflection of this endothelial dysfunction is the severe impairment in endothelium-dependent vasodilation that occurs early after transplantation. The etiology of this allograft endothelial alteration is multifactorial and may include preexisting atherosclerosis of the graft vessels, reperfusion injury during transplantation, denervation, disruption of the lymphatic system, and acute and chronic immune injury, as well as traditional risk factors for coronary artery disease (hyperlipidemia, diabetes, hypertension, or hyperhomocysteinemia) and pathogens, such as cytomegalovirus. The alteration in endothelial function affects vasomotor tone of the coronary arteries. Evidence indicates that there may be an impairment of endothelial production and/or activity of NO. Because NO is a potent vasodilator, its deficiency would explain the abnormal vasomotor tone in these individuals. In addition, because NO inhibits key processes in vascular inflammation and atherosclerosis, its absence may contribute to the acceleration of transplant vascular disease. Recent studies from our group and others have shed light on the mechanisms of endothelial dysfunction and its importance in cardiac allograft vasculopathy. In addition, the alteration in endothelial function contributes to vascular inflammation and progression of the disease.

Synergistic induction of intercellular adhesion molecule-1 by the human cytomegalovirus transactivators IE2p86 and pp71 is mediated via an Sp1-binding site

Human cytomegalovirus (HCMV) infection of transplant recipients is frequently associated with allograft vasculopathy and rejection. One potential mechanism is vascular injury from HCMV-triggered, immunologically mediated processes. HCMV infection has been shown to increase the expression of intercellular adhesion molecule-1 (ICAM-1). The objective of this study was to determine the molecular basis of HCMV-enhanced ICAM-1 gene expression. Transient transfection experiments identified the IE2p86 protein as a potent activator of the ICAM-1 promoter. The tegument protein pp71 showed a strong synergistic effect on IE2p86-mediated ICAM-1 promoter activation. Mutagenesis experiments defined a DNA element from -110 to -42 relative to the transcription start site as responsive for IE2p86. Further point mutations within this DNA element identified an Sp1-binding site that was essential for strong synergistic activation by IE2p86 and pp71. To confirm the activation of ICAM-1 gene expression, human fibroblasts (HFF) as well as endothelial cells (HUVEC) were infected with recombinant IE2p86- and pp71-expressing baculoviruses, respectively. In FACS analysis, a synergistic induction of ICAM-1 was detectable when cells were co-infected with the two recombinant baculoviruses. These findings clearly demonstrate that IE2p86 and pp71 are crucial regulatory factors for HCMV-induced ICAM-1 upregulation.

Interleukin-1-mediated inhibition of cytomegalovirus replication is due to increased IFN-beta production

Previous studies have demonstrated that the intercellular spread of cytomegalovirus (CMV) is reduced in marrow stromal cells that either secrete interleukin-1 (IL-1) or are treated with exogenous IL-1. Here, we report that IL-1-treated marrow stromal cells and fibroblasts, when infected with CMV, produce decreased amounts of infectious progeny virus. CMV-infected cells treated with IL-1 contained more interferon-beta (IFN-beta) mRNA at 24 h postinfection compared with untreated, infected cells. IFN-beta protein secreted into fibroblast culture supernatants increased from 46 +/- 1 IU/ml in untreated, infected cells to 116 +/- 5 IU/ml in IL-1-treated infected cells. When IFN-beta activity was inhibited, using blocking antibodies to either the cytokine or the IFN-alpha/beta receptor, the addition of IL-1 no longer limited viral spread. Furthermore, viral spread in nonIL-1-treated cultures was inhibited by the addition of recombinant IFN-beta. These studies suggest that IL-1 functions to limit CMV spread by increasing the expression of IFN-beta, which in turn reduces production of infectious virus.

Human cytomegalovirus infection of bone marrow myofibroblasts enhances myeloid progenitor adhesion and elicits viral transmission

Human cytomegalovirus (CMV) infection of bone marrow transplant recipients can cause pancytopenia, as well as life-threatening interstitial pneumonia. CMV replicates actively in bone marrow stromal cells, whereas it remains latent in hematopoietic progenitors. Our aim was to study the influence of CMV infection on adherence of CD34(+) cells to the myofibroblastic component of human bone marrow and examine transmission of virus from myofibroblasts to CD34(+) cells. We show that smooth actin, but not fibronectin, organization is markedly modified by CMV infection of bone marrow stromal myofibroblasts. Nonetheless, CMV infection led to increased adherence of the CD34(+) progenitor cell line, KG1a, relative to adherence to uninfected myofibroblasts from the same donors. Adherence of CD34(+) cells to infected bone marrow myofibroblasts resulted in transfer of virions and viral proteins through close cell-to-cell contacts. This phenomenon may play a role in the pathophysiology of CMV bone marrow infection and in eventual virus dissemination.

The cellular delivery of antisense oligonucleotides and ribozymes

The design and development of antisense oligonucleotides and ribozymes for the treatment of diseases arising from genetic abnormalities has become a real possibility over the past few years. Improvements in oligonucleotide chemistry have led to the synthesis of nucleic acids that are relatively stable in the biological milieu. However, advances in cellular targeting and intracellular delivery will probably lead to more widespread clinical applications. This review looks at recent advances in the in vitro and in vivo delivery of antisense oligodeoxynucleotides and ribozymes.

The delivery of antisense therapeutics

Antisense oligonucleotides, ribozymes and DNAzymes have emerged as novel, highly selective inhibitors or modulators of gene expression. Indeed, their use in the treatment of diseases arising from genetic abnormalities has become a real possibility over the past few years. The first antisense drug molecule is now available for clinical use in Europe and USA. However, their successful application in the clinic will require improvements in cellular targeting and intracellular delivery. This review aims to look at recent advances in the in vitro and in vivo delivery of antisense oligodeoxynucleotides and ribozymes.

Gene therapy and molecular approaches to the treatment of hereditary muscular disorders

Gene therapy for inherited muscle disease is an active area of research and development. Initial emphasis has been on gene replacement but alternative approaches are increasingly being considered in order to overcome difficulties, such as the immune rejection of transduced cells, the need for appropriate and tissue-specific control of expression, and the requirement for systemic spread in some conditions. However, the most significant obstacles to the clinical success of gene therapy are still the lack of efficiency and accuracy of gene medicine delivery.