ABSTRACT
OBJECTIVE: The coxsackie and adenovirus receptor (CAR) mediates the entry of coxsackievirus B (CVB) and adenovirus into host cells and is, therefore, a key determinant for the molecular pathogenesis of viral diseases such as myocarditis. The aim was to investigate the influence of HMG-CoA reductase inhibitor lovastatin on CAR expression in endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to different concentrations of lovastatin (0.05-5 µmol/l) for up to 48 h. Alterations in CAR expression were examined by quantitative real-time PCR (qRT-PCR) and flow cytometry. In addition, after treatment with 1 µmol/l lovastatin for 48 h, HUVECs were infected for 8 h with CVB3 and virus replication was detected by qRT-PCR using viral-specific TaqMan probes. RESULTS: We found that lovastatin decreases CAR mRNA expression by up to 80% (p < 0.01) and CAR protein expression by up to 19% (p < 0.01), in a concentration-dependent manner. Moreover, virus replication of CVB3 was significantly inhibited after lovastatin treatment (p < 0.05). The signaling mechanism of CAR down-regulation by lovastatin depends on the Rac1/Cdc42 pathway. CONCLUSION: This study shows for the first time that lovastatin reduces the expression of CAR and subsequently the replication of CVB3 in HUVECs.
Subject(s)
Coxsackie and Adenovirus Receptor-Like Membrane Protein/antagonists & inhibitors , Enterovirus B, Human/drug effects , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology , Lovastatin/pharmacology , Cells, Cultured , Coxsackie and Adenovirus Receptor-Like Membrane Protein/genetics , Coxsackie and Adenovirus Receptor-Like Membrane Protein/metabolism , Coxsackievirus Infections/drug therapy , Coxsackievirus Infections/metabolism , Coxsackievirus Infections/virology , Enterovirus B, Human/physiology , Human Umbilical Vein Endothelial Cells/drug effects , Human Umbilical Vein Endothelial Cells/metabolism , Human Umbilical Vein Endothelial Cells/virology , Humans , RNA, Messenger/metabolism , RNA, Small Interfering/genetics , Virus Replication/drug effects , cdc42 GTP-Binding Protein/genetics , cdc42 GTP-Binding Protein/metabolism , rac1 GTP-Binding Protein/genetics , rac1 GTP-Binding Protein/metabolismABSTRACT
In viral myocarditis, adeno- and enteroviruses have most commonly been implicated as causes of infection. Both viruses require the human coxsackie-adenovirus receptor (CAR) to infect the myocardium. Due to its crucial role for viral entry, CAR-downregulation may lead to novel approaches for treatment for viral myocarditis. In this study, we report on pharmaceutical drug influences on CAR levels in human umbilical vein endothelial cells (HUVEC) and cervical carcinoma cells (HeLa) detected by immunoblotting, quantitative real time-PCR and cellular susceptibility to the cardiotropic coxsackie-B3 virus strain Nancy (CVB3). Our results indicate, for the first time, a dose-dependent CAR mRNA and protein downregulation upon Valsartan and Bosentan treatment. Most interestingly, drug-induced CAR diminution significantly reduced the viral load in CVB3-infected HUVEC. In order to assess the regulatory effects of both drugs in detail, we knocked down their protein targets, the G-protein coupled receptors angiotensin-II type-1 receptor (AT(1)R) and endothelin-1 type-A and -B receptors (ET(A)R/ET(B)R) in HUVEC. Receptor-specific gene silencing indicates that CAR gene expression is regulated by agonistic and antagonistic binding to ET(B)R, but not ET(A)R. In addition, neither stimulation nor inhibition of AT(1)R seemed to be involved in CAR gene regulatory processes. Our study indicates that Valsartan and Bosentan protected human endothelial cells from CVB3-infection. Therefore, besides their well-known anti-hypertensive effects these drugs may also protect the myocardium and other tissues from coxsackie- and adenoviral infection.
