Varicella Zoster Virus Alters Expression of Cell Adhesion Proteins in Human Perineurial Cells via Interleukin 6.

BACKGROUND: In temporal arteries (TAs) from patients with giant cell arteritis, varicella zoster virus (VZV) is seen in perineurial cells that surround adventitial nerve bundles and form the peripheral nerve-extrafascicular tissue barrier (perineurium). We hypothesized that during VZV reactivation from ganglia, virus travels transaxonally and disrupts the perineurium to infect surrounding cells. METHODS: Mock- and VZV-infected primary human perineurial cells (HPNCs) were examined for alterations in claudin-1, E-cadherin, and N-cadherin. Conditioned supernatant was analyzed for a soluble factor(s) mediating these alterations and for the ability to increase cell migration. To corroborate in vitro findings, a VZV-infected TA was examined. RESULTS: In VZV-infected HPNCs, claudin-1 redistributed to the nucleus; E-cadherin was lost and N-cadherin gained, with similar changes seen in VZV-infected perineurial cells in a TA. VZV-conditioned supernatant contained increased interleukin 6 (IL-6) that induced E-cadherin loss and N-cadherin gain and increased cell migration when added to uninfected HPNCs; anti-IL-6 receptor antibody prevented these changes. CONCLUSIONS: IL-6 secreted from VZV-infected HPNCs facilitated changes in E- and N-cadherin expression and cell migration, reminiscent of an epithelial-to-mesenchymal cell transition, potentially contributing to loss of perineurial cell barrier integrity and viral spread. Importantly, an anti-IL-6 receptor antibody prevented virus-induced perineurial cell disruption.

Varicella zoster virus differentially alters morphology and suppresses proinflammatory cytokines in primary human spinal cord and hippocampal astrocytes.

BACKGROUND: Varicella zoster virus (VZV) is a ubiquitous alphaherpesvirus that produces varicella and zoster. VZV can infect multiple cell types in the spinal cord and brain, including astrocytes, producing myelopathy and encephalopathy. While studies of VZV-astrocyte interactions are sparse, a recent report showed that quiescent primary human spinal cord astrocytes (qHA-sps) did not appear activated morphologically during VZV infection. Since astrocytes play a critical role in host defenses during viral infections of the central nervous system, we examined the cytokine responses of qHA-sps and quiescent primary human hippocampal astrocytes (qHA-hps) to VZV infection in vitro, as well as the ability of conditioned supernatant to recruit immune cells. METHODS: At 3 days post-infection, mock- and VZV-infected qHA-sps and qHA-hps were examined for morphological changes by immunofluorescence antibody assay using antibodies directed against glial fibrillary acidic protein and VZV. Conditioned supernatants were analyzed for proinflammatory cytokines [interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, interferon-gamma, and tumor necrosis factor-α] using the Meso Scale Discovery multiplex ELISA platform. Finally, the ability of conditioned supernatants to attract peripheral blood mononuclear cells (PBMCs) was determined using a chemotaxis assay. Quiescent primary human perineurial cells (qHPNCs) served as a control for VZV-induced cytokine production and PBMC migration. To confirm that the astrocytes have the ability to increase cytokine secretion, qHA-sps and qHA-hps were treated with IL-1ß and examined for morphological changes and IL-6 secretion. RESULTS: VZV-infected qHA-sps displayed extensive cellular processes, whereas VZV-infected qHA-hps became swollen and clustered together. Astrocytes had the capacity to secrete IL-6 in response to IL-1ß. Compared to mock-infected cells, VZV-infected qHA-sps showed significantly reduced secretion of IL-2, IL-4, IL-6, IL-12p70, and IL-13, while VZV-infected qHA-hps showed significantly reduced IL-8 secretion. In contrast, levels of all 10 cytokines examined were significantly increased in VZV-infected qHPNCs. Consistent with these results, conditioned supernatant from VZV-infected qHPNCs, but not that from VZV-infected qHA-sps and qHA-hps, recruited PBMCs. CONCLUSIONS: VZV-infected qHA-sps and qHA-hps have distinct morphological alterations and patterns of proinflammatory cytokine suppression that could contribute to ineffective viral clearance in VZV myelopathy and encephalopathy, respectively.

Varicella-Zoster Virus Downregulates Programmed Death Ligand 1 and Major Histocompatibility Complex Class I in Human Brain Vascular Adventitial Fibroblasts, Perineurial Cells, and Lung Fibroblasts.

Varicella-zoster virus (VZV) vasculopathy produces stroke, giant cell arteritis, and granulomatous aortitis, and it develops after virus reactivates from ganglia and spreads transaxonally to arterial adventitia, resulting in persistent inflammation and pathological vascular remodeling. The mechanism(s) by which inflammatory cells persist in VZV-infected arteries is unknown; however, virus-induced dysregulation of programmed death ligand 1 (PD-L1) may play a role. Specifically, PD-L1 can be expressed on virtually all nucleated cells and suppresses the immune system by interacting with the programmed cell death protein receptor 1, found exclusively on immune cells; thus, downregulation of PD-L1 may promote inflammation, as seen in some autoimmune diseases. Both flow cytometry and immunofluorescence analyses to test whether VZV infection of adventitial cells downregulates PD-L1 showed decreased PD-L1 expression in VZV-infected compared to mock-infected human brain vascular adventitial fibroblasts (HBVAFs), perineural cells (HPNCs), and fetal lung fibroblasts (HFLs) at 72 h postinfection. Quantitative RT-PCR analyses showed no change in PD-L1 transcript levels between mock- and VZV-infected cells, indicating a posttranscriptional mechanism for VZV-mediated downregulation of PD-L1. Flow cytometry analyses showed decreased major histocompatibility complex class I (MHC-I) expression in VZV-infected cells and adjacent uninfected cells compared to mock-infected cells. These data suggest that reduced PD-L1 expression in VZV-infected adventitial cells contribute to persistent vascular inflammation observed in virus-infected arteries from patients with VZV vasculopathy, while downregulation of MHC-I prevents viral clearance. IMPORTANCE: Here, we provide the first demonstration that VZV downregulates PD-L1 expression in infected HBVAFs, HPNCs, and HFLs, which, together with the noted VZV-mediated downregulation of MHC-I, might foster persistent inflammation in vessels, leading to pathological vascular remodeling during VZV vasculopathy and persistent inflammation in infected lungs to promote subsequent infection of T cells and hematogenous virus spread. Identification of a potential mechanism by which persistent inflammation in the absence of effective viral clearance occurs in VZV vasculopathy and VZV infection of the lung is a step toward targeted therapy of VZV-induced disease.

Simian Varicella Virus Is Present in Macrophages, Dendritic Cells, and T Cells in Lymph Nodes of Rhesus Macaques after Experimental Reactivation.

UNLABELLED: Like varicella-zoster virus (VZV), simian varicella virus (SVV) reactivates to produce zoster. In the present study, 5 rhesus macaques were inoculated intrabronchially with SVV, and 5 months later, 4 monkeys were immunosuppressed; 1 monkey was not immunosuppressed but was subjected to the stress of transportation. In 4 monkeys, a zoster rash developed 7 to 12 weeks after immunosuppression, and a rash also developed in the monkey that was not immunosuppressed. Analysis at 24 to 48 h after zoster revealed SVV antigen in the lung alveolar wall, in ganglionic neurons and nonneuronal cells, and in skin and in lymph nodes. In skin, SVV was found primarily in sweat glands. In lymph nodes, the SVV antigen colocalized mostly with macrophages, dendritic cells, and, to a lesser extent, T cells. The presence of SVV in lymph nodes, as verified by quantitative PCR detection of SVV DNA, might reflect the sequestration of virus by macrophages and dendritic cells in lymph nodes or the presentation of viral antigens to T cells to initiate an immune response against SVV, or both. IMPORTANCE: VZV causes varicella (chickenpox), becomes latent in ganglia, and reactivates to produce zoster and multiple other serious neurological disorders. SVV in nonhuman primates has proved to be a useful model in which the pathogenesis of the virus parallels the pathogenesis of VZV in humans. Here, we show that SVV antigens are present in sweat glands in skin and in macrophages and dendritic cells in lymph nodes after SVV reactivation in monkeys, raising the possibility that macrophages and dendritic cells in lymph nodes serve as antigen-presenting cells to activate T cell responses against SVV after reactivation.