Expression of coxsackievirus and adenovirus receptor in neointima of the rat carotid artery

Liver-specific Coxsackievirus and adenovirus receptor deletion develop metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a common liver disease associated with obesity and is caused by the accumulation of ectopic fat without alcohol consumption. Coxsackievirus and adenovirus receptor (CAR) are vital for cardiac myocyte-intercalated discs and endothelial cell-to-cell tight junctions. CAR has also been reported to be associated with obesity and high blood pressure. However, its function in the liver is still not well understood. The liver of obese mice exhibit elevated CAR mRNA and protein levels. Furthermore, in the liver of patients with non-alcoholic steatohepatitis, CAR is reduced in hepatocyte cell-cell junctions compared to normal levels. We generated liver-specific CAR knockout (KO) mice to investigate the role of CAR in the liver. Body and liver weights were not different between wild-type (WT) and KO mice fed a paired or high-fat diet (HFD). However, HFD induced significant liver damage and lipid accumulation in CAR KO mice compared with WT mice. Additionally, inflammatory cytokines transcription, hepatic permeability, and macrophage recruitment considerably increased in CAR KO mice. We identified a new interaction partner of CAR using a protein pull-down assay and mass spectrometry. Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3C (APOBEC3C) demonstrated a complex relationship with CAR, and hepatic CAR expression tightly regulated its level. Moreover, Apolipoprotein B (ApoB) and Low-density lipoprotein receptor (LDLR) levels correlated with APOBEC3C expression in the liver of CAR KO mice, suggesting that CAR may regulate lipid accumulation by controlling APOBEC3C activity. In this study, we showed that hepatic CAR deficiency increased cell-to-cell permeability. In addition, CAR deletion significantly increased hepatic lipid accumulation by inducing ApoB and LDLR expression. Although the underlying mechanism is unclear, CARs may be a target for the development of novel therapies for MAFLD.

Vascular Endothelial Integrity Affects the Severity of Enterovirus-Mediated Cardiomyopathy

Coxsackievirus and adenovirus receptor (CAR) is present in epithelial and vascular endothelial cell junctions. We have previously shown a hemorrhagic phenotype in germ-line CAR knock-out mouse embryos; we have also found that CAR interacts with ZO-1 and β-catenin. However, the role of CAR in vascular endothelial junction permeability has not been proven. To understand the roles of CAR in the vascular endothelial junctions, we generated endothelium-specific CAR knockout (CAR-eKO) mice. In the absence of CAR, the endothelial cell layer showed an increase in transmembrane electrical resistance (TER, Ω) and coxsackievirus permeability. Evans blue dye and 70 kDa dextran-FITC were delivered by tail vein injection. We observed increased vascular permeability in the hearts of adult CAR-eKO mice compare with wild-type (WT) mice. There was a marked increase in monocyte and macrophage penetration into the peritoneal cavity caused by thioglycolate-induced peritonitis. We found that CAR ablation in endothelial cells was not significantly increased coxsackievirus B3 (CVB3) induced myocarditis in murine model. However, tissue virus titers were significantly higher in CAR-eKO mice compared with WT. Moreover, CVB3 was detected in the brain of CAR-eKO mice. Endothelial CAR deletion affects the expression of major endothelial junction proteins, such as cadherin and platelet endothelial cell adhesion molecule-1 (PECAM-1) in the cultured endothelial cells as well as liver vessel. We suggest that CAR expression is required for normal vascular permeability and endothelial tight junction homeostasis. Furthermore, CVB3 organ penetration and myocarditis severities were dependent on the endothelial CAR level.

Transduction Efficiency of Adenovirus Vectors in Endothelial Cells and Vascular Smooth Muscle Cells

Adenoviral vectors are useful tools in manipulating a gene of interest in vitro and in vivo, including in the vascular system. The transduction efficiencies of adenoviral vectors in vascular cells such as endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are known to be lower than those in epithelial cell types. The effective entry for adenoviral vectors is primarily mediated through the coxsackievirus and adenovirus receptor (CAR), which has been shown to be expressed in both cell types. Cationic liposomes have been used to enhance adenovirus transduction efficiency in nonepithelial cells. Accordingly, the aim of this study is to obtain new information regarding differences in transduction efficiencies, cationic liposome sensitivity, and CAR expression between ECs and VSMCs. Using cultured rat aortic ECs and VSMCs, here, we have compared transduction efficiency of adenoviruses with or without inclusion of liposomes and CAR expression. A significant increase in basal transduction efficiency was observed in ECs compared with VSMCs. Cationic liposome polybrene enhanced transduction efficiency in VSMCs, whereas decreased efficiency was observed in ECs. Western blotting demonstrated expression of the CAR in ECs but not in VSMCs. Proteomic analysis and mouse aorta immunostaining further suggests significant expression of the CAR in ECs but not in VSMCs. In conclusion, adenoviruses can effectively transduce the gene of interest in aortic ECs likely because of abundant expression of the CAR, whereas cationic liposomes such as polybrene enhance the transduction efficiency in VSMCs lacking CAR expression.

Loss of Endothelial Barrier in Marfan Mice (mgR/mgR) Results in Severe Inflammation after Adenoviral Gene Therapy

Objectives

Marfan syndrome is an autosomal dominant inherited disorder of connective tissue. The vascular complications of Marfan syndrome have the biggest impact on life expectancy. The aorta of Marfan patients reveals degradation of elastin layers caused by increased proteolytic activity of matrix metalloproteinases (MMPs). In this study we performed adenoviral gene transfer of human tissue inhibitor of matrix metalloproteinases-1 (hTIMP-1) in aortic grafts of fibrillin-1 deficient Marfan mice (mgR/mgR) in order to reduce elastolysis.

Methods

We performed heterotopic infrarenal transplantation of the thoracic aorta in female mice (n = 7 per group). Before implantation, mgR/mgR and wild-type aortas (WT, C57BL/6) were transduced ex vivo with an adenoviral vector coding for human TIMP-1 (Ad.hTIMP-1) or β-galactosidase (Ad.β-Gal). As control mgR/mgR and wild-type aortas received no gene therapy. Thirty days after surgery, overexpression of the transgene was assessed by immunohistochemistry (IHC) and collagen in situ zymography. Histologic staining was performed to investigate inflammation, the neointimal index (NI), and elastin breaks. Endothelial barrier function of native not virus-exposed aortas was evaluated by perfusion of fluorescent albumin and examinations of virus-exposed tissue were performed by transmission electron microscopy (TEM).

Results

IHC and ISZ revealed sufficient expression of the transgene. Severe cellular inflammation and intima hyperplasia were seen only in adenovirus treated mgR/mgR aortas (Ad.β-Gal, Ad.hTIMP-1 NI: 0.23; 0.43), but not in native and Ad.hTIMP-1 treated WT (NI: 0.01; 0.00). Compared to native mgR/mgR and Ad.hTIMP-1 treated WT aorta, the NI is highly significant greater in Ad.hTIMP-1 transduced mgR/mgR aorta (p = 0.001; p = 0.001). As expected, untreated Marfan grafts showed significant more elastolysis compared to WT (p = 0.001). However, elastolysis in Marfan aortas was not reduced by adenoviral overexpression of hTIMP-1 (compared to untreated Marfan aorta: Ad.hTIMP-1 p = 0.902; control Ad.β-Gal. p = 0.165). The virus-untreated and not transplanted mgR/mgR aorta revealed a significant increase of albumin diffusion through the endothelial barrier (p = 0.037). TEM analysis of adenovirus-exposed mgR/mgR aortas displayed disruption of the basement membrane and basolateral space.

Conclusions

Murine Marfan aortic grafts developed severe inflammation after adenoviral contact. We demonstrated that fibrillin-1 deficiency is associated with relevant dysfunction of the endothelial barrier that enables adenovirus to induce vessel-harming inflammation. Endothelial dysfunction may play a pivotal role in the development of the vascular phenotype of Marfan syndrome.

Effect of imatinib mesylate and rapamycin on the preformed intimal hyperplasia in rat carotid injury model

PURPOSE

Intimal hyperplasia (IH) is the main cause of restenosis or occlusion after vascular procedures. Imatinib mesylate and rapamycin are known to prevent IH. The purpose of this study was to evaluate the effect of these drugs on the regression of preformed IH in rat carotid injury model.

METHODS

IH was established in rat carotid arteries using a balloon catheter. The drug effects were assessed in vitro on proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) in the neointima. And in vivo studies were carried out in 4 groups: imatinib, rapamycin, combined, and no medication. After 2-week oral medication, morphometric analysis evaluated the number and density of neointimal cells, intima-to-media (I/M) ratio and cross-sectional area. Cell proliferation, apoptosis, and collagen changes were also investigated by immunohistochemical staining (IHCS).

RESULTS

Imatinib and rapamycin significantly inhibited VSMC proliferation and migration, and promoted apoptosis in vitro. In morphometric analysis, the number and density of neointimal cells decreased significantly in all medication groups compared with control group (P < 0.01). However, there was no significant difference in neointimal cross-sectional area and I/M ratio among groups. In IHCS, imatinib and rapamycin inhibited neointimal cell proliferation significantly. However, there was no significant change in cell apoptosis and collagen composition.

CONCLUSION

Combined treatment of with imatinib and rapamycin induced reduction of cell mass in preformed intimal hyperplasia, but failed to induce regression of intimal mass in this short-term medication study. Further studies will be needed with additional strategies of inducing lysis of the extracellular matrix.

Erythropoietin, but not asialoerythropoietin or carbamyl-erythropoietin, attenuates monocrotaline-induced pulmonary hypertension in rats

Erythropoietin (EPO) has long been utilized for the treatment of renal anemia. The erythropoietin receptor (EPOR) is also expressed in the cardiovascular and central nervous systems in addition to an erythroid lineage, to provide an organoprotective role against several types of cellular stress. Pulmonary hypertension (PH) is a poor prognostic disease caused by primary and secondary pulmonary vascular injury. We observed the effects of EPO derivatives on monocrotaline-induced PH in rats on the supposition that EPO may protect small arteries from injury. Asialoerythropoietin (AEPO) lacks sialic acids in the termini of carbohydrate chains that results in rapid clearance from blood. Carbamyl-erythropoietin (CEPO) interacts with EPOR/βc heterodimers, but not with EPOR homodimers expressed in erythroid cells. Monocrotaline-injected rats were treated with continuous intravenous injection of 2500 ng/kg/day of EPO, AEPO, or CEPO for 21 days, and lung histology, cardiac function, and mRNA expression in the lungs were examined. Wall thickening of small arteries in the lungs and PH were improved by administration of EPO, but not by its non-hematopoietic derivatives, AEPO, or CEPO. Erythropoietin administration increased mRNA expression of the anti-apoptotic molecule, Bcl-xL, and maintained expression of the CD31 antigen. We conclude that lungs may express EPOR homoreceptors, but not heteroreceptors. Adequate serum erythropoietin levels may be essential for pulmonary protective effects.

Restituting intestinal epithelial cells exhibit increased transducibility by adenoviral vectors

BACKGROUND AND AIMS

While mature enterocytes are resistant to transduction by adenovirus type 5 (Ad5) vectors, undifferentiated cells are transduced much more efficiently. Our purpose was to study enterocyte transduction in models of intestinal wound healing.

METHODS

Transduction was studied ex vivo using cultures of endoscopic biopsies and in vitro utilizing Caco-2 cells in models of mucosal wound healing. Vectors carried either the LacZ or the luciferase gene. CAR (coxsackievirus and adenovirus receptor) and integrins were studied with transduction inhibition and immunofluorescent staining.

RESULTS

Increased transduction efficiency was observed for a subset of enterocytes with a flattened de-differentiated phenotype present at the edge of cultured biopsies. In the in vitro systems, expanding Caco-2 cell monolayers exhibited increased transducibility that was time- and dose-dependent, reaching virtually 100% in cells along the leading edge at high viral load. Bioluminescence activity of transduced expanding monolayers was up to 3-fold greater than that of non-expanding monolayers ('fence' system, 48 h, MOI 1000, p < 0.05). Mitomycin C pre-treatment did not affect levels of transduction in expanding monolayers. At the highest viral load tested, CAR or integrin blocking prior to virus application resulted in 39.4% and 45.4% reduction in transduction levels (p < 0.05). Immunofluorescence revealed altered expression of CAR on the migrating edge of the Caco-2 cultures and the expression of CAR on the apical membrane of biopsy enterocytes.

CONCLUSIONS

Increased CAR and integrin accessibility in migrating enterocytes mediates increased transduction by Ad5 vectors. This subset of enterocytes provides a target for the delivery of genes of interest for both research and gene therapy applications.

Coxsackie and adenovirus receptor (CAR) is a product of Sertoli and germ cells in rat testes which is localized at the Sertoli-Sertoli and Sertoli-germ cell interface

The coxsackie and adenovirus receptor (CAR), a putative cell-cell adhesion molecule, has attracted wide interest due to its importance in viral pathogenesis and in mediating adenoviral gene delivery. However, the distribution pattern and physiological function of CAR in the testis is still not clear. Here, we identified CAR in Sertoli cells and germ cells of rats. In vivo studies have shown that CAR resides at the blood-testis barrier as well as at the ectoplasmic specialization. The persistent expression of CAR in rat testes from neonatal period throughout adulthood implicates its role in spermatogenesis. Using primary Sertoli cell cultures, we observed a significant induction of CAR during the formation of Sertoli cell epithelium. Furthermore, CAR was seen to be concentrated at inter-Sertoli cell junctions, co-localizing with tight junction protein marker ZO-1 and adherens junction protein N-cadherin. CAR was also found to be associated with proteins of Src kinase family and its protein level declined after TNFalpha treatment in Sertoli cell cultures. Immunofluorescent staining of isolated germ cells has revealed the presence of CAR on spermatogonia, spermatocytes, round spermatids and elongate spermatids. Taken together, we propose that CAR functions as an adhesion molecule in maintaining the inter-Sertoli cell junctions at the basal compartment of the seminiferous epithelium. In addition, CAR may confer adhesion between Sertoli and germ cells at the Sertoli-germ cell interface. It is possible that the receptor utilized by viral pathogens to breakthrough the epithelial barrier was also employed by developing germ cells to migrate through the inter-Sertoli cell junctions.

Cell type- and region- dependent coxsackie adenovirus receptor expression in the central nervous system

Model systems have shown that adenoviral vector mediated transient gene expression can potentially be applied for the treatment of brain tumours, neurodegenerative diseases and brain injuries. Most studies utilized adenovirus serotype 5 (Ad5) based vectors, which as adhesion molecules require the coxsackie adenovirus receptor (CAR) as a critical determinant for cellular infection. In this report, we have systematically characterized CAR expression in the adult human central nervous system (CNS) by using immunohistochemistry. A total of 85 specimens from various CNS regions were investigated for CAR expression in a cell type-dependent context. The most marked staining positivity was found in the choroid plexus and the pituitary gland. The neocortex had scattered positive neurons, while the white matter was mainly negative. We need to consider the possible adverse effects and the possible damage caused by adenoviral gene therapy if the virus-vector also binds to normal brain cells.

Coxsackievirus-adenovirus receptor (CAR) is essential for early embryonic cardiac development

The coxsackievirus-adenovirus receptor (CAR) is a cell contact protein on various cell types with unknown physiological function. It belongs to a subfamily of the immunoglobulin-superfamily of which some members are junctional adhesion molecules on epithelial and/or endothelial cells. CAR is dominantly expressed in the hearts and brains of mice until the newborne phase after which it becomes mainly restricted to various epithelial cells. To understand more about the physiological function of CAR, we have generated CAR-deficient mice by gene targeting. We found that these mice die between E11.5 and E13.5 of embryonal development. Ultrastructural analysis of cardiomyocytes revealed that the density of myofibrils was reduced and that their orientation and bundling was disorganized. In addition, mitochondria were enlarged and glycogen storage strongly enriched. In line with these defects, we observed pericardial edema formation as a clear sign of insufficient heart function. Developmental abnormalities likely to be secondary effects of gene ablation were the persistent singular cardial atrio-ventricular canal and dilatations of larger blood vessels such as the cardinal veins. The secondary nature of these defects was supported by the fact that CAR was not expressed on vascular cells or on cells of the vascular wall. No obvious signs for alterations of the histological organization of the placenta were observed. We conclude that CAR is required for embryonal heart development, most likely due to its function during the organization of myofibrils in cardiomyocytes.