No abstract

Human cytomegalovirus (HCMV) infection of smooth muscle cells (SMCs) in vivo has been linked to a viral etiology of vascular disease. In this report, we demonstrate that HCMV infection of primary arterial SMCs results in significant cellular migration. Ablation of the chemokine receptor, US28, abrogates SMC migration, which is rescued only by expression of the viral homolog and not a cellular G protein-coupled receptor (GPCR). Expression of US28 in the presence of CC chemokines including RANTES or MCP-1 was sufficient to promote SMC migration by both chemokinesis and chemotaxis, which was inhibited by protein tyrosine kinase inhibitors. US28-mediated SMC migration provides a molecular basis for the correlative evidence that links HCMV to the acceleration of vascular disease.

On the basis of these data, it is concluded that balloon angioplasty is safe and effective in the treatment of native aortic coarctation; significant incidence of recoarctation is seen in neonates and infants; repeat balloon angioplasty for recoarctation is feasible and effective; and the time has come to consider balloon angioplasty as a therapeutic procedure of choice for the treatment of native aortic coarctation.

Gypsy displays striking similarities to vertebrate retroviruses, including the presence of a yet uncharacterized additional open reading frame (ORF3) and the recent evidence for infectivity. It is mobilized with high frequency in the germline of the progeny of females homozygous for the flamenco permissive mutation. We report the characterization of a gypsy subgenomic ORF3 RNA encoding typical retroviral envelope proteins. In females, env expression is strongly repressed by one copy of the non‐permissive allele of flamenco. A less dramatic reduction in the accumulation of other transcripts and retrotranscripts is also observed. These effects correlate well with the inhibition of gypsy transposition in the progeny of these females, and are therefore likely to be responsible for this phenomenon. The effects of flamenco on gypsy expression are apparently restricted to the somatic follicle cells that surround the maternal germline. Moreover, permissive follicle cells display a typically polarized distribution of gypsy RNAs and envelope proteins, both being mainly accumulated at the apical pole, close to the oocyte. We propose a model suggesting that gypsy germinal transposition might occur only in individuals that have maternally inherited enveloped gypsy particles due to infection of the maternal germline by the soma.

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Cytomegalovirus (CMV) infections have been shown to dramatically affect solid organ transplant graft survival in both human and animal models. Recently, it was demonstrated that rat CMV (RCMV) infection accelerates the development of transplant vascular sclerosis (TVS) in both rat heart and small bowel graft transplants. However, the mechanisms involved in this process are still unclear. In the present study, we determined the kinetics of RCMV-accelerated TVS in a rat heart transplant model. Acute RCMV infection enhances the development of TVS in rat heart allografts, and this process is initiated between 21 and 24 days posttransplantation. The virus is consistently detected in the heart grafts from day 7 until day 35 posttransplantation but is rarely found at the time of graft rejection (day 45 posttransplantation). Grafts from RCMV-infected recipients had upregulation of chemokine expression compared to uninfected controls, and the timing of this increased expression paralleled that of RCMV-accelerated neointimal formation. In addition, graft vessels from RCMV-infected grafts demonstrate the increased infiltration of T cells and macrophages during periods of highest chemokine expression. These results suggest that CMV-induced acceleration of TVS involves the increased graft vascular infiltration of inflammatory cells through enhanced chemokine expression.With the escalation in the number of immunosuppressed patients undergoing immunosuppressive therapy following solid organ or bone marrow transplantation, human cytomegalovirus (HCMV) disease has now become a major clinical problem. While the majority of HCMV infections result in subclinical disease in healthy individuals, HCMV is a significant pathogen in immunocompromised patients (1,3,4,9,26,33,34,50,51,56). Primary HCMV infection is followed by lifelong persistence of the virus in a latent state, and reactivation of the latent virus is considered to be the major source of virus in these immunocompromised individuals. HCMV has been linked to the development of atherosclerosis, arterial restenosis following angioplasty, and solid organ transplant vascular sclerosis (TVS) (26)(27)(28)47). HCMV infection doubles the 5-and 3-year rates of graft failure due to accelerated TVS in cardiac and liver transplant patients, respectively (15; L. W. Miller, Editorial, J. Heart Lung Transplant. 11:S1-S4, 1992). The observation that HCMV infects many of the cell types involved in vascular disease, including monocyte-derived macrophages, endothelial cells, and smooth muscle cells (SMC), suggests that HCMV may play a role in these disease processes. Because of the similarities between the CMV-speciesspecific viruses, animal models provide an ideal tool to study the association between CMV and TVS.The most compelling evidence that herpesviruses play a role in vascular disease comes from studies in animal models. Using a rat CMV (RCMV) solid organ transplant model, researchers have demonstrated, in light of the RCMV-associated acceleration of TVS, an association of herpesvirus ...

Targeting recycling endocytic receptors with specific Abs provides a means for introducing a variety of tumor-associated Ags into human dendritic cells (DCs), culminating in their efficient presentation to T cells. We have generated a human mAb (B11) against the mannose receptor that is rapidly internalized by DCs through receptor-mediated endocytosis. By genetically linking the melanoma Ag, pmel17, to Ab B11, we obtained the fully human fusion protein, B11-pmel17. Treatment of DCs with B11-pmel17 resulted in the presentation of pmel17 in the context of HLA class I and class II molecules. Thus, potent pmel17-specific T cells were cytotoxic toward gp100+ HLA-matched melanoma targets, but not HLA-mismatched melanoma or gp100− nonmelanoma tumor lines. Importantly, competitive inhibition of lysis of an otherwise susceptible melanoma cell line by cold targets pulsed with known gp100 CD8 T cell epitopes as well as a dose-dependent proliferative response to Th epitopes demonstrates that DCs can process targeted Ag for activation of cytotoxic as well as helper arms of the immune response. Thus, the specific targeting of soluble exogenous tumor Ag to the DC mannose receptor directly contributes to the generation of multiple HLA-restricted Ag-specific T cell responses.

A decreased clearance of apoptotic cells (efferocytosis) by alveolar macrophages (AM) may contribute to inflammation in emphysema. The up-regulation of ceramides in response to cigarette smoking (CS) has been linked to AM accumulation and increased detection of apoptotic alveolar epithelial and endothelial cells in lung parenchyma. We hypothesized that ceramides inhibit the AM phagocytosis of apoptotic cells. Release of endogenous ceramides via sphingomyelinase or exogenous ceramide treatments dose-dependently impaired apoptotic Jurkat cell phagocytosis by primary rat or human AM, irrespective of the molecular species of ceramide. Similarly, in vivo augmentation of lung ceramides via intratracheal instillation in rats significantly decreased the engulfment of instilled target apoptotic thymocytes by resident AM. The mechanism of ceramide-induced efferocytosis impairment was dependent on generation of sphingosine via ceramidase. Sphingosine treatment recapitulated the effects of ceramide, dose-dependently inhibiting apoptotic cell clearance. The effect of ceramide on efferocytosis was associated with decreased membrane ruffle formation and attenuated Rac1 plasma membrane recruitment. Constitutively active Rac1 overexpression rescued AM efferocytosis against the effects of ceramide. CS exposure significantly increased AM ceramides and recapitulated the effect of ceramides on Rac1 membrane recruitment in a sphingosinedependent manner. Importantly, CS profoundly inhibited AM efferocytosis via ceramide-dependent sphingosine production. These results suggest that excessive lung ceramides may amplify lung injury in emphysema by causing both apoptosis of structural cells and inhibition of their clearance by AM.