Thrombin induces Sp1-mediated antiviral effects in cytomegalovirus-infected human retinal pigment epithelial cells

The role of protease-activated receptor 1 signaling in CD8 T cell effector functions

CD8 T cells are essential for adaptive immunity against viral infections. Protease activated receptor 1 (PAR1) is expressed by CD8 T cells; however, its role in T cell effector function is not well defined. Here we show that in human CD8 T cells, PAR1 stimulation accelerates calcium mobilization. Furthermore, PAR1 is involved in cytotoxic T cell function by facilitating granule trafficking via actin polymerization and repositioning of the microtubule organizing center (MTOC) toward the immunological synapse. In vivo, PAR1-/- mice have reduced cytokine-producing T cells in response to a lymphocytic choriomeningitis virus (LCMV) infection and fail to efficiently control the virus. Specific deletion of PAR1 in LCMV GP33-specific CD8 T cells results in reduced expansion and diminished effector function. These data demonstrate that PAR1 plays a role in T cell activation and function, and this pathway could represent a new therapeutic strategy to modulate CD8 T cell effector function.

Multiscale Analysis of Independent Alzheimer's Cohorts Finds Disruption of Molecular, Genetic, and Clinical Networks by Human Herpesvirus

Investigators have long suspected that pathogenic microbes might contribute to the onset and progression of Alzheimer's disease (AD) although definitive evidence has not been presented. Whether such findings represent a causal contribution, or reflect opportunistic passengers of neurodegeneration, is also difficult to resolve. We constructed multiscale networks of the late-onset AD-associated virome, integrating genomic, transcriptomic, proteomic, and histopathological data across four brain regions from human post-mortem tissue. We observed increased human herpesvirus 6A (HHV-6A) and human herpesvirus 7 (HHV-7) from subjects with AD compared with controls. These results were replicated in two additional, independent and geographically dispersed cohorts. We observed regulatory relationships linking viral abundance and modulators of APP metabolism, including induction of APBB2, APPBP2, BIN1, BACE1, CLU, PICALM, and PSEN1 by HHV-6A. This study elucidates networks linking molecular, clinical, and neuropathological features with viral activity and is consistent with viral activity constituting a general feature of AD.

Protease-activated receptor 1 inhibition protects mice against thrombin-dependent respiratory syncytial virus and human metapneumovirus infections

BACKGROUND AND PURPOSE

Protease-activated receptor 1 (PAR1) has been demonstrated to be involved in the pathogenesis of viral diseases. However, its role remains controversial. The goal of our study was to investigate the contribution of PAR1 to respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) infections.

EXPERIMENTAL APPROACH

Pharmacological approaches were used to investigate the role of PAR1 during RSV and hMPV infection, in vitro using epithelial A549 cells and in vivo using a mouse model of virus infection.

KEY RESULTS

In vitro, the PAR1 antagonist RWJ-56110 reduced the replication of RSV and hMPV in A549 cells. In agreement with these results, RWJ-56110-treated mice were protected against RSV and hMPV infections, as indicated by less weight loss and mortality. This protective effect in mice correlated with decreased lung viral replication and inflammation. In contrast, hMPV-infected mice treated with the PAR1 agonist TFLLR-NH₂ showed increased mortality, as compared to infected mice, which were left untreated. Thrombin generation was shown to occur downstream of PAR1 activation in infected mice via tissue factor exposure as part of the inflammatory response, and thrombin inhibition by argatroban reduced the pathogenicity of the infection with no additive effect to that induced by PAR1 inhibition.

CONCLUSION AND IMPLICATIONS

These data show that PAR1 plays a detrimental role during RSV and hMPV infections in mice via, at least, a thrombin-dependent mechanism. Thus, the use of PAR1 antagonists and thrombin inhibitors may have potential as a novel approach for the treatment of RSV and hMPV infections.

Pathogenesis and treatment of human immunodeficiency virus-associated cytomegalovirus retinitis

In the era of HAART, human cytomegalovirus (HCMV) retinitis remains the leading opportunistic ocular infection and the major cause of blindness in patients with AIDS. The virus has been subjected to selection and presented with the opportunity to occupy a niche to which it is highly adapted in order to escape from host immune recognition and establish persistent infection in the retina. The imbalance between host immune protection and viral immune evasion results in retinitis progression. Moreover, a synergistic interaction between HCMV and HIV in the pathogenesis of retinitis has been proposed. HAART has had a major beneficial impact on the prognosis for HIV-infected individuals. Both HAART and specific anti-HCMV treatment contribute to therapeutic success against HCMV retinitis in AIDS patients. The improved prognosis for AIDS patients with respect to the development of HCMV retinitis has been welcomed; however, we should bear in mind the occurrence of HIV drug resistance, relapse of retinitis and immune recovery uveitis after treatment, which mean that this complication of HIV infection remains a threat.

Epidemiology of human cytomegalovirus (HCMV) in an urban region of Germany: what has changed?

Since the dynamics of transmission of human cytomegalovirus (HCMV) have not been clarified yet, we assessed a possible change in HCMV seroprevalence in Frankfurt am Main, Germany during the past twenty years and tried to detect variables with an impact on epidemiology. Between 1/1/1988 and 10/15/2008, a total of 54443 serum samples were collected for routine diagnostics and analyzed using Enzygnost Anti HCMV-IgG enzyme immunoassay (Siemens/Dade Behring, Marburg, Germany). Two decades, 1/1/1988-12/31/1997 and 1/1/1998-10/15/2008, and several groups (type of health insurance, gender, age, HIV-status) were evaluated to assess changes in seroprevalence. Regarding both decades, the overall age-adjusted prevalence of HIV-negative patients dropped from 63.70% (confidence interval (CI) 95% 63.15-64.25) to 57.25% (CI 95% 56.57-57.93; P < 0.0001). Private health insurance (PHI) patients showed significant lower HCMV seroprevalences than members of obligatory health insurances (OHI) in both decades (1988-1997: PHI = 55.79%, OHI = 64.27%; P < 0.0001; 1998-1908: PHI = 47.02%, OHI = 58.74%; P < 0.0001). Furthermore, comparing the two decades, there was generally a gender-specific statistically significant decrease in HCMV seroprevalence for males (63.54-55.54%) and females (63.83-58.73%) as well as for members of PHI and OHI (PHI males: 57.59% to 47.19%, PHI females 54.10-46.80%; OHI males: 64.00-57.06%, OHI females 64.50-60.11%). Also, while female HIV-positive patients showed significant difference in HCMV seroprevalence between the two decades (83.17 and 87.80%, P = 0.023), there was no significant difference in male patients with HIV (88.76 and 87.32% in the first and second decade, respectively (P = 0.196). The cumulative HCMV prevalence of all HIV-negative patients tested in the past 20 years demonstrates a biphasic, age-related rise of HCMV seroprevalence throughout all age-groups. The seroprevalence of HCMV has declined between 1988-1997 and 1998-2008 in Frankfurt am Main, Germany. The decline varied between different age-groups. HCMV prevalence correlates with the type of health insurance, gender, age, and HIV-status.

Activated protein C therapy slows ALS-like disease in mice by transcriptionally inhibiting SOD1 in motor neurons and microglia cells

Activated protein C (APC) is a signaling protease with anticoagulant activity. Here, we have used mice expressing a mutation in superoxide dismutase-1 (SOD1) that is linked to amyotrophic lateral sclerosis (ALS) to show that administration of APC or APC analogs with reduced anticoagulant activity after disease onset slows disease progression and extends survival. A proteolytically inactive form of APC with reduced anticoagulant activity provided no benefit. APC crossed the blood-spinal cord barrier in mice via endothelial protein C receptor. When administered after disease onset, APC eliminated leakage of hemoglobin-derived products across the blood-spinal cord barrier and delayed microglial activation. In microvessels, motor neurons, and microglial cells from SOD1-mutant mice and in cultured neuronal cells, APC transcriptionally downregulated SOD1. Inhibition of SOD1 synthesis in neuronal cells by APC required protease-activated receptor-1 (PAR1) and PAR3, which inhibited nuclear transport of the Sp1 transcription factor. Diminished mutant SOD1 synthesis by selective gene excision within endothelial cells did not alter disease progression, which suggests that diminished mutant SOD1 synthesis in other cells, including motor neurons and microglia, caused the APC-mediated slowing of disease. The delayed disease progression in mice after APC administration suggests that this approach may be of benefit to patients with familial, and possibly sporadic, ALS.