Enhanced neutrophil activity is associated with shorter time to tumor progression in glioblastoma patients.

Glioblastoma multiforme (GBM) is a highly malignant tumor with a poor outcome that is often positive for human cytomegalovirus (HCMV). GBM patients often have excessive numbers of neutrophils and macrophages near and within the tumor. Here, we characterized the cytokine patterns in the blood of GBM patients with and without Valganciclovir treatment. Furthermore, we determined whether neutrophil activation is related to HCMV status and patient outcome. Blood samples for analyses of cytokines and growth factors were collected from 42 GBM patients at the time of diagnosis (n = 42) and at weeks 12 and 24 after surgery. Blood neutrophils of 28 GBM patients were examined for CD11b expression. The levels of pro- and anti-inflammatory cytokines and chemokines-including interleukin (IL)-1ß, IL-2, IL-6, IL-8, IL-10, IL-12p70, IL-17A, transforming growth factor (TGF)-ß1, interferon-γ, interferon-α, tumor necrosis factor α, and monocyte chemoattractant protein (MCP)-1were analyzed with a bead-based flow cytometry assay. During the first six months after surgery, neutrophil activity was increased in 12 patients and was unchanged or decreased in 16. Patients with increased neutrophil activity had enhanced IL-12p70, high grade HCMV and a shorter time to tumor progression (TTP) than patients without or decreased neutrophil activity (median TTP; 5.4 vs. 12 months, 95% confidence interval; 1.6-10 vs. 0.1-0.6, hazard ratio = 3 vs. 0.4, p = 0.004). The levels of IL-12p70 were significantly decreased in Valganciclovir treated patients (n = 22, T 12W vs. T 24W, p = 0.03). In conclusion, our findings suggest that neutrophil activation is an early sign of tumor progression in GBM patients.

Human neural stem cells and astrocytes, but not neurons, suppress an allogeneic lymphocyte response.

Transplantation of human neural stem cells (NSCs) and their derivatives is a promising future treatment for neurodegenerative disease and traumatic nervous system lesions. An important issue is what kind of immunological reaction the cellular transplant and host interaction will result in. Previously, we reported that human NSCs, despite expressing MHC class I and class II molecules, do not trigger an allogeneic T cell response. Here, the immunocompetence of human NSCs, as well as differentiated neural cells, was further studied. Astrocytes expressed both MHC class I and class II molecules to a degree equivalent to that of the NSCs, whereas neurons expressed only MHC class I molecules. Neither the NSCs nor the differentiated cells triggered an allogeneic lymphocyte response. Instead, these potential donor NSCs and astrocytes, but not the neurons, exhibited a suppressive effect on an allogeneic immune response. The suppressive effect mediated by NSCs most likely involves cell-cell interaction. When the immunogenicity of human NSCs was tested in an acute spinal cord injury model in rodent, a xenogeneic rejection response was triggered. Thus, human NSCs and their derived astrocytes do not initiate, but instead suppress, an allogeneic response, while they cannot block a graft rejection in a xenogeneic setting.

HCMV infection of PDCs deviates the NK cell response into cytokine-producing cells unable to perform cytotoxicity.

Plasmacytoid dendritic cells (PDCs) are thought to induce natural killer (NK) cell CD69 expression, cytotoxicity, and cytokine secretion. Since human cytomegalovirus (HCMV) interferes with multiple functions of infected cells, we investigated whether the HCMV infection of PDCs affects NK cell activation. Human PDCs infected with HCMV strain VR1814 at multiplicity of infection (MOI) 10 or stimulated with control CpG-A were cocultured with human NK cells in an autologous system. As expected, CpG-stimulation of PDCs increased expression of the NK cell activation marker CD69, enhanced cytotoxicity and stimulated secretion of tumor necrosis factor (TNF)-alpha and IFN-alpha, but not IFN-gamma, and induced NK cell migration. In contrast, incubation with HCMV-infected PDCs induced CD69 expression, migration and elevated production of both TNF-alpha and IFN-gamma by NK cells, but these cells did not exhibit enhanced cytotoxicity. Also, HCMV-infected PDCs were unable to induce increased intracellular perforin levels. Thus, HCMV infection of PDCs induce NK cells to increase CD69 expression and produce inflammatory cytokines, but infected PDCs are unable to induce NK cell cytotoxicity. This NK cell phenotype with impaired killing abilities, but enhanced production of inflammatory cytokines may instead facilitate reactivation and replication of HCMV. This data indicate that HCMV can target PDCs through novel dual strategies that may result in evasion of the innate immune response at the same time as facilitating virus reactivation and replication early in the infection, through enhanced inflammation.

Human cytomegalovirus differentially controls B cell and T cell responses through effects on plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (PDCs), the main producers of type I IFN in response to viral infection, are essential in antiviral immunity. In this study, we assessed the effect of human CMV (HCMV) infection on PDC function and on downstream B and T cell responses in vitro. HCMV infection of human PDCs was nonpermissive, as immediate-early but not late viral Ags were detected. HCMV led to partial maturation of PDCs and up-regulated MHC class II and CD83 molecules but not the costimulatory molecules CD80 and CD86. Regardless of viral replication, PDCs secreted cytokines after contact with HCMV, including IFN-alpha secretion that was blocked by inhibitory CpG, suggesting an engagement of the TLR7 and/or TLR9 pathways. In the presence of B cell receptor stimulation, soluble factors produced by HCMV-matured PDCs triggered B cell activation and proliferation. Through PDC stimulation, HCMV prompted B cell activation, but only induced Ab production in the presence of T cells or T cell secreted IL-2. Conversely, HCMV hampered the allostimulatory ability of PDCs, leading to decreased proliferation of CD4(+) and CD8(+) T cells. These findings reveal a novel mechanism by which HCMV differentially controls humoral and cell-mediate immune responses through effects on PDCs.